Volume 33(2) 2021
Table of Contents
|1.||An Overview of Recent Advances and Novel Synthetic Approaches for Lignocellulosic derived Biofuels
Mohammad Siddique, Suhail Ahmed Soomro, Shaheen Aziz & Faheem Akhter*
One of the most important challenges to overcome at present is to reduce the dependability on the fossil fuels and replace them with green and environmental friendly substitutes. In this respect, biofuel conversion from lignocellulosic materials could prove to be an efficient process. The current review presents the most recent advances and novel synthetic approaches in utilizing lignocellulosic substrates for biofuel production, such as scheming of new/enhanced catalysts, waste valorization, using genetic modifications to improve organism traits, development and/improving the new or step integration processes, etc. Such new strategies can prove to be important tools and augment the use of renewable fuels globally. The present review summarizes the most recent strategies, advances and novel synthetic approaches offered pertaining to catalytic/non-catalytic pretreatments/transformations of lignocellulosic materials, carbohydrates based carbohydrates and technical lignin into biofuels.
Keywords : Waste valorization; biofuels; lignocellulosic biomass; catalysts
|2.||Plant and Non-plant based Polymeric Coagulants for Wastewater Treatment: A Review
Faheem Akhter*, Suhail Ahmed Soomro, Mohammad Siddique & Mansoor Ahmed
The major source of fresh water is rain, which ultimately streams down into oceans and rivers. This water is consumed by the human beings for various purposes. All the consuming channels of this water, such as domestic, industrial, agricultural etc. generate the wastewater. Furthermore, urbanization and population growth are also the prime contributors. The reason why this water is called wastewater is due to the presence of contaminants such as organic material, biological components and toxic compounds, hence they have adverse effect on human health. Conventionally, many of the inorganic materials have been used as coagulants to treat the wastewater as these compounds have the ability to alter the physico-chemical properties. The present paper reviews the polymeric coagulants used for wastewater treatment that are green, sustainable and efficient. Moreover, these natural polymeric coagulants are biodegradable, eco-friendly and without any adverse effects on human health.
Keywords: Polymeric coagulants; wastewater; plant based; non-plant based
Original Research Papers
|3.||Evaluating Actual Speed Against the Permissible Speed of Vehicles DuringFree-Flow Traffic Conditions
Nur Farhanatul Syasya Mohd Azwari & Abdul Azeez Kadar Hamsa*
It is commonly seen that vehicles were moving above the speed limit on many expressways especially during free-flow traffic conditions. To ensure safe movement of vehicles, it is important to compare the actual speed of the vehicles against the posted speed limit. The main purpose of this paper is to evaluate and compare the actual speed of the vehicles with the allowable speed limit during free-flow traffic conditions. Duta-Ulu Kelang Expressway (DUKE) was selected as a case study. Major data were collected by using road geometrical survey and spot speed survey method. Around 400 vehicles’ speed were measured at a selected road stretch for 4 hours during off-peak period. Systematic sampling technique was used to select samples from the targeted vehicle population. Descriptive statistical methods were used to analyze the speed trends and speed characteristics of the sampled vehicles. T-test was applied to test the actual speed between each selected hour and to test the differences between actual average vehicle speed and allowable speed limit for statistical significance. The results show most of the vehicles (66%), on average, were moving at a speed higher than the allowable speed limit of 90 km/h. The differences between actual average speed and allowable speed limit were tested for statistical significance which as a result indicates a clear difference between actual average speed and allowable speed limit. Few recommendations are drawn to discourage excessive speed in order to make the roads free from accidents and to improve the safety of the road users.
Keywords: Spot speed, road geometrical design, road safety, speed limit, DUKE
|4.||Structural Performance of One-Way Slabs Reinforced with Steel and Polypropylene Fibers
Qaiser uz Zaman Khan; Afaq Ahmad*, Ali Raza, Mojtaba Labibzadeh & Muhammad Iqbal
The present study aims to investigate the effects of the steel fibers (SF) and polypropylene fibers (PPF) on the structural response of one-way simply supported reinforced concrete (RC) slabs at the ultimate limit state (ULS). Next, an optimized combination of the hybrid fibers is proposed. The experimental program includes 21 experiments on the one-way slabs with different SF and PPF ratios. The load-deflection curves were obtained for slabs using a four-point bending method. The ultimate capacity and mid-span deflection of the slabs were measured. The experimental results did not produce a consistent trend of ultimate loading. The different blends produced different failure modes, cracking load, and ultimate failure load. Based on the obtained test results, the slab specimen, SM6, with 0.7% SF and 0.9% PPF ratios has the maximum and the slab specimen, SM16, with 0.9% SF and 0.9% PPF ratios has the minimum load-carrying capacity, respectively. The first shows a 31% increase and the second indicates a 31% reduction when compared to the reference slab specimen, SM1, which has no fibers used in its concrete mixture. It is worth to mention that the slab specimen, SM6, which has the largest load-carrying capacity, also shows the highest ductility (172% enlargement in deflection when compared to the reference slab, SM1).
Keywords: Hybrid Fiber-reinforced concrete slabs; Flexural testing; One-way slabs; Polypropylene fibers; Load-carrying capacity; Ductility
|5.||Improvements of TPS-Porous Asphalt Using Wax- Based Additives for the Application on Malaysian Expressway
Satis Kumar Selvadurai, Mohd Rosli Mohd Hasan*, Ashiru Sani, Nakanishi Hiromitsu, Meor Othman Hamzah & Sharvin Poovaneshvaran
Porous asphalt provides a sustainable approach to reduce traffic noise at source, while at the same time offering storm-water management systems which promote infiltration and often reduce the need for a detention pool. However, porous asphalt is prone to premature deteriorations, in terms of ravelling, and air voids clogging, rendering its unpopularity as the road surfacing material for expressways construction. In this research, the comparative influences of Tough Fix (TF) and Tough Fix Hyper (TFH) additives incorporation were evaluated on the performance of Tafpack-Super modified porous asphalt mixtures (TPS-PA). The Tafpack-Super (TPS) as a modifier at 20%, and anti-stripping additives (TF and TFH) with dosages used in this study were 0.3%, and 0.15% based on the weight of asphalt binder, respectively. Initially, the PA mixtures were prepared according to a predetermined mix design, and verified based on the percentage of air voids, permeability, and connected air voids. Comprehensive experimental tests of Marshall stability, permeability, Cantabro loss, rutting resistance, and moisture induced damage resistance were performed to assess the mechanical performance of the TPS-PA mixtures. Moreover, the Texas boiling test was employed to assess the stripping potential of loose TPS-PA mixtures. The experimental results revealed that both TF and TFH are capable of improving the PA resistance against rutting, ravelling, and moisture damage. In addition, the porous asphalt with TFH anti-stripping agent incorporation exhibited a superior overall performance as compared to the PA with TF.
Keywords: Abrasion resistance; asphalt-aggregates bonding; moisture damage; porous asphalt pavement, ravelling
|6.||Database Development for Water Quality Index using Geographical Information System
Nadia Natasha Salim, Mustaffa Anjang Ahmad*, Nasradeen A Khalifa & Adel Al-Gheethi
The present study aimed to identify drainage pollution at Parit Raja, Johor in accordance to the Water Quality Index (WQI) and based on Geographic Information System (GIS) data analysis. A total of 18 sampling stations at six drainage ditches were selected to be sampling points. The parameters investigated included Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Suspended Solid (SS), Ammonia Nitrogen (AN) and pH. ArcGIS software was selected and the water quality data were gathered and digitized in the GIS as data storage system in order to develop database. The results revealed that 13 stations were categorized as polluted, 5 stations classified as slightly polluted. These findings indicated that GIS have an ability to provide interactive visual and attribute information effectively in order to improve water quality management system. Therefore, GIS can be applied on a big study area and this is useful for wastewater management by authorities.
Keywords: Water pollution; Water Quality Index; Geographical Information System
|7.||A Case Study of Carbon Emissions from Logistic Activities During Supply Chain Disruptions
Siti Zubaidah Amiruddin, Hawa Hishamuddin*, Noraida Azura Darom & Hilmi Hisyam Naimin
Supply chain disruptions have significant negative effects on logistics operations, in which recovery actions could in turn affect the environment if certain green precautions are not undertaken. The objective of this research is to assess the effect of disruption on carbon emissions from logistics activities in the supply chain. A case study was carried out in this study to identify the factors of supply chain disruptions that affect logistics operations, and investigate the impact of the disruptions on the environment. Data collection using the Fuel Monitor application and real disruption data from a selected company were used to quantify the carbon emissions during disruption and non-disruption scenarios. Analysis of the study found that carbon emissions during disruption events increased to approximately 18 – 20 % as compared to normal operations. This is due to the increase in travelling distance in order to fulfill customer backorders during the disruption occurrence. The carbon emission amount was slightly higher when using fuel consumption as reference data in comparison to distance travelled, as fuel consumption takes into account the driving behaviour and efficiency of the truck engines. This study is useful for analyzing the impact of supply chain disruptions on the environment, particularly from the post-disruption recovery decisions.
Keywords: Disruption; supply chain; carbon emission; logistics
|8.||Forced Convective Heat Transfer Analysis for Two-dimensional Slot Jet of Water-CuO Nanofluid
Amin Etminan* & Zambri Harun*
This paper investigates the effect of the diameter and the volume fraction variation of the centre nanoparticles on the heat transfer characteristics of a two-dimensional slot jet. The jet impinges on stationary flat, convex, and concave aluminium plates. A forced convective heat transfer coefficient of water-CuO nanofluid impinges on a smooth plate under a constant heat flux. The finite volume method (FVM) is implemented for nanoparticles with diameters varying from 7 to 60 nanometers, volume fractions changing from 0 to 5%, and the Reynolds numbers ranging from 1800 to 2800. A grid independence study is carried out to find a grid size that predicts the results accurately and further grid refinement changes the results insignificantly. The single-phase model shows a capability to predicts the fluid and heat transfer parameters faster and make it more suitable for numerical simulations compared to the two-phase model. The results indicate a higher heat transfer coefficient of nanofluid in comparison with distilled water. As the Reynolds number and nanoparticle volume concentrations increase, the heat transfer rate increases on the surface whilst smaller nanoparticle diameters increase during the cooling process. The increase in the diameter of nanoparticles enhances the Nusselt number on the plate by up to 10%. The same geometrical details, thermophysical, and boundary conditions have been employed in all calculations for distilled water jet simulations to validate the fluid flow behaviour and heat transfer parameters with available experimental data in the literature.
Keywords: Heat Transfer; turbulent flow; slot jet; nanofluid; CuO nanoparticle
|9.||Computational Fluid Dynamics Simulation of Fluidized Bed Dryer for Sago Pith Waste Drying Process.
Abdul Mu’im Abdul Nasir, Masli Irwan Rosli*, Mohd Sobri Takriff, Nur Tantiyani Ali Othman & Vinotharan Ravichandar
Sago pith waste (SPW) has a great potential in becoming numerous kinds of reusable products as it has high level of starch content after went through drying process. Without proper treatment the disposal of SPW could cause serious environmental problem. The drying process of SPW using fluidized bed dryer (FBD) was found to be more effective than other drying methods. Thus, in this study the process was analyzed using computational fluid dynamics (CFD) modelling with the developed three-dimensional FBD model. The fluidization profile was studied from the analysis done using ANSYS Fluent 19.2 software which include certain process flow and set up to create similar situation as the experimental condition by also taking into account the moisture content of SPW. Both approach of drying process were executed at air inlet temperature of 50ºC and velocity at 1.50 ms-1. Using the sample of SPW that initially at 40% wet basis the result of fluidization from experimental and simulation were comparable in term of particles profiles and percentage of moisture content which show closely resemblance of decreasing trend. The outcome was however having a slight different of moisture content at 15th minute of experimental approach which could be resolved by improving the model in term of zone condition of the simulation setup. This study is however is an initial part to study about SPW drying using CFD solution as there are more to be discovered with this advantageous tool that is able to perform and provide much more analysis and outcomes in much shorter time and cost saving way base on the experimental method.
Keywords: Computational Fluid Dynamics (CFD), Drying; Sago pith waste; Fluidized Bed Dryer (FBD)
|10.||Simulation Study on the Effect of Dielectrophoresis Force on a Separation of Platelet from Blood Cell in a 3D Mini Channel
Nur Tantiyani Ali Othman* & C. S. Lee
In recent years, separation of platelet from a blood cell received growing attention due to its usages for blood disorders or any disease treatment. However, the conventional separation techniques have some constraint due to its limitation to separate the cells with similar properties, costly, requires longer processing time, and less data accuracy. Thus, under the effect of a uniform electric field, a dielectrophoretic (DEP) force was applied as its ability to separate on a similar diameter size of cells, has lower cost, and requires only a small volume of sample. In this study, a 3D mini channel model with a Y-shape was developed using AutoCAD® and the velocity profile distribution was observed using ANSYS© Fluent version 19.1. Three parameters were observed at various an electric field intensity; E=±1 to ±5 V/mm, an electric field frequency, f=1 kHz to 1 MHz and a particle diameter; d=1.3 to 2.0μm. The results show the velocity was increased as the higher of electric field intensity and larger particle diameter. Besides, the DEP force was increased as the higher electric field intensity was charged for all tested frequencies. As well, as the higher the electric field intensity charged and the larger the particle diameter, the stronger of the DEP force. It can be concluded that the DEP force at d=2.0μm and E=5 V/mm was the optimum conditions and obtained the highest result among all the tested parameters. Under these optimum conditions, it shows the DEP force can separate the platelet from the blood cells.
Keywords: Cell platelet, dielectrophoresis; mini channel; separation; ANSYS©; AutoCAD©
|11.||Experimental and Numerical Analyses of Wind-Induced Noise in Two-Way Radios
Wan Masrurah Hairudin, Ummi Masyitah Mohd Fisol & Norilmi Amilia Ismail
The generation of wind noise of entrance microphone cavities owing to turbulent airflow is an inherent problem with radio telecommunication systems, such as two-way radios. It will lead to a pressure fluctuation which is highly unpleasant and would degrade a two-way radio communication. This research aims to understand the relationship between noise level and the flow structure of the different parameters to the occurrence of noise during communication using a two-way radio device. A noise measurement is conducted to analyse the sound pressure level (SPL) within a cavity, in which computational fluid dynamic(CFD) is used to investigate the flow behaviour on the various effects of cavity positions at P1, P2, P3, P4, and P5 and wind velocities of 0.75 m/s, 1.49 m/s, 2.24 m/s, 2.99 m/s and 3.75 m/s which corresponding to Reynolds number (Re) of 8694, 17389, 26083, 34777, and 43471 respectively. CFD result showed the presence of separation of the shear layer, the development of vortex shedding, the recirculation region and vorticity were present inside the edges of the cavity. SPL increased with an increase in wind velocity and, the cavity distance of P4. In the cavity position of P5, SPL is decreased due to the wind velocity exceeding the maximum level of a wind tunnel. Therefore, the cavity position of P5 is suitable for reducing wind noise. These parameters are significant for improving the design of two-way radio to reduce the noise during outdoor communication.
Keywords: Wind-induced noise; CFD; Sound pressure level (SPL); microphone cavity; two-way radio; cavity
|12.||Numerical Evaluation of Structural Concrete Insulated Panels for Thermal Energy Efficient Buildings
Sohaib Ahmed & Anwar Khitab*
This study is focused on thermal evaluation of Structural Concrete Insulation Panels (SCIPs) as building material. In Pakistan energy shortage is one of major issues since the last decade. As buildings consume more than 40 % of total production of electrical energy, it is necessary to innovate, analyse and apply various energy saving and optimization techniques for constructing thermal energy efficient buildings. SCIPs consist of three layers, in which a central polystyrene foam is sandwiched between two concrete layers. SCIPs are available in flexible sizes ranging from 0.3-1.2 m in width and 2.4-3.0 m in length. Owing to their light weight and easy fabrication, they are suitable for remote areas and severe weather conditions. In this study, numerical approach is used to compare the thermal performances of SCIPs and ordinary concrete incorporated walls in a school building system. Hourly recorded data of dry-bulb and dew-point temperatures of surface, humidity and mean air temperatures are used in simulation. Data for one typical year are used to compare the energy requirements of building made of ordinary concrete and SCIPs walls with expanded polystyrene as insulation material. Simulation results were acquired by means of EnergyPlus software and are presented to evaluate the heating and cooling demands of energy for a year. Study reveals that the SCIP walls incorporated buildings have a greater energy efficiency, reduce energy demand by 25% and HVAC systems by 20 % for assigned thermal zone.
Keywords: Structural Concrete Insulation Panels (SCIPs); ordinary concrete; buildings; EnergyPlus software; energy demand; HVAC system size
|13.||Pengekstrakan Amonia-Nitrogen dan Ortofosfat daripada Efluen Kilang Sawit dalam Bentuk Struvit
Teow Yeit Haan*, Nor Maizatul Aqilah Mohamad Azman, Hal Hamid Pakeer Mohamed, Yuan Xin Teoh, Nor Azier Mohd Nor & Maha Mohammad AL-Rajabi
Ammonia-nitrogen (NH3-N) and orthophosphate (PO43-) contain in palm oil mill effluent will cause toxicity to aquatic life and polluted water source. However, these substances could be use as fertilizer for plant. Nitrogen and phosphorus are the mandatory nutrient source for the plant growth. This study studied the effect of pH and magnesium weight on the effectiveness of the extraction of ammonia-nitrogen (NH3-N) and orthophosphate (PO43-) from palm oil mill effluent (POME) in the form of struvite (MgNH4PO4•6H2O). The effect of pH on percent removal of NH3-N and PO43- from POME was studied by manipulating the pH of POME at constant the weight of magnesium chloride (MgCl2). Meanwhile, the effect of MgCl2 on the percentage removal of NH3-N and PO43- from POME was studied by manipulating the weight of MgCl2 at constant pH of POME. The concentrations of NH3-N and PO43- were determined using spectrophotometers and struvites were characterized using fourier-transform infrared (FTIR). This study showed that pH is an important factor in the extraction of NH3-N and PO43- ions in the form of struvit. pH 11.5 is the optimum pH to achieve the effective extraction process of NH3-N and PO43- from POME in the form of struvit. Addition of the MgCl2 did not have a significant effect on the extraction process because POME contained sufficient magnesium ions for the extraction process. The highest NH3-N and PO43− removal was attained at pH 11.5 with the addition of 0.5 g MgCl2. 93.72% NH3-N and 86.15% PO43- were removed from POME in struvit extraction process. The resulting struvit yield was also identified through FTIR analysis by the existence of O-H bond, N-H bond, and P-O bond.Abstrak Bahasa Malaysia
Amonia-nitrogen (NH3-N dan ortofosfat (PO43-) yang terkandung dalam efluen kilang sawit (POME) akan mengakibatkan ketoksikan kepada hidupan akuatik dan juga menyebabkan sumber air manusia terjejas. Namun, ia dapat digunakan sebagai baja alternatif untuk tumbuh-tumbuhan sedangkan nitrogen dan fosforus merupakan sumber nutrien yang utuma bagi tumbuhan. Kajian ini mengkaji kesan pH dan kesan berat sumber magnesium ke atas keberkesanan pengekstrakkan NH3-N dan PO43- daripada POME dalam bentuk struvit (MgNH4PO4•6H2O). Kesan pH terhadap peratus penyingkiran NH3-N dan PO43- dari POME dikaji dengan memanipulasikan nilai pH POME dengan menetapkan berat magnesium chloride (MgCl2). Manakala, kajian kesan berat MgCl2 terhadap peratus penyingkiran NH3-N dan PO43- dari POME dikaji dengan memanipulasikan berat MgCl2 dengan menetapkan nilai pH POME. Kepekatan NH3-N dan PO43- dikenalpastikan dengan menggunakan spektrofotometer dan struvit yang terbentuk dicirikan dengan menggunakan infra-merah transformasi fourier (FTIR). Kajian ini menunjukkan pH merupakan faktor yang penting dalam mempengaruhi proses pengekstrakan NH3-N dan ion PO43- dalam bentuk struvit. pH 11.5 merupakan pH optimum untuk mencapai keberkesanan proses pengekstrakkan NH3-N dan PO43- daripada POME dalam bentuk struvit yang maxima. Penambahan kuatiti MgCl2 tidak membawa kesan yang besar kepada proses pengekstrakan kerana POME telah mengandungi ion magnesium yang mencukupi untuk proses pengekstrakan. Peratusan penyingkiran NH3-N dan PO43- yang tertinggi tercapai pada pH 11.5 dengan penambahan 0.5g MgCl2, bersamaan dengan 93.72% NH3-N dan 86.15% PO43-. Mendakan yang terhasil juga dikenalpasti sebagai struvit melalui analisis FTIR dengan pembuktian kewujudan ikatan O-H, ikatan N-H, dan ikatan P-O.
Keywords: Palm oil mill effluent (POME); ammonia-nitrogen; orthophosphate; extraction process; struvit
|14.||Damages of Orthotropic Bridge Deck Surfacing: Forensic Investigation, Remedial Work and Performance Monitoring
Conventional mastic asphalt typically lasts for more than two decades when being used as bridge surfacing. However substantial increase in heavy goods traffic and higher axle loading has led to some severe cracks in the surfacing during the first ten years since opening to traffic. A forensic investigation into the defects was subsequently carried out. The investigation comprised site inspection, reviewing available records, laboratory testing, designing new surfacing system and recommending remedial actions. The site inspection identified structural and functional damages, which were subsequently assessed in the laboratory on samples taken from site followed by detailed analysis. Laboratory assessments included stiffness, tensile strength and rheology of the existing mastic asphalt surfacing and the waterproofing layer. These suites of testing were followed by Finite Element Models (FEMs) which were developed specifically to analyze movements of the deck, including the cantilever and the main decks, for a range of traffic levels and speeds, considering the mechanical properties determined from the laboratory tests. From the review of literatures and worldwide case studies, three alternative surfacing system options were identified. Prediction of the residual life of the existing surfacing and the projected life of the recommended replacement systems were analyzed. The effect of super single wheel loading on the proposed system was also assessed. Based on the relative performance of these options, recommendations were presented to improve the surfacing design for use in the interim maintenance and remedial works. Follow up works included monitoring the in service performance of the interim solution since opening to traffic. For the future major rehabilitation works, three alternative options have been advised to replace the current surfacing system. The benefits of each of these options have also been presented to assist with decision making, in consideration of the cost and the technical side.
Keywords: Surfacing damage; forensic investigation; mastic asphalt; FEM; performance monitoring
|15.||Computer Aided Simulation POME Biogas Purification System
Andrew Yap Kian Chung* & Ummi Kalsum Hasanah M.N
About three (3) tonnes of palm oil mill effluent (POME) is generated when one (1) tonne of crude palm oil (CPO) is produced. Microbial digestion treatment is commonly used in Malaysian palm oil mills due to the low capital expenditure (CAPEX) and operational expenditure (OPEX). However, anaerobic digestion of POME produces methane gas which is 21 times more harmful than carbon dioxide. 1m3 of POME could generate 27m3 of biogas at standard temperature and pressure with approximate caloric value of 20 MJm-3 under optimum conditions Thus, methane capturing biogas plant to address sustainability issue is included as part of effluent treatment plant. Many mills start to utilise the biogas energy to replace palm kernel shell which could be sold as renewable solid fuel. Although untreated biogas may be good enough for boiler fuel, internal combustion engines need a fairly homogeneous fuel with methane (CH4) content up to 80 % and hydrogen sulphite (H2S) content less than 200 ppm in order to ensure the optimum engine performance. Water scrubber system is widely used in gas purification. Computer aided biogas purification system simulation involving water scrubber and flashing drum is presented in the effort to produce IC engine fuel. ChemCAD simulation result shows that POME biogas purification process is feasible at 10 bar pressure and 25°C ambient temperature.
Keywords: Biogas; carbon dioxide; ChemCAD; palm oil mill effluent; water scrubber
|16.||Accurate Path-Loss Estimation for Wireless Cellular Networks
Ibrahim M M Mohamed*
In addition to its rule in achieving acceptable system performance, accurate path-loss estimation leads to realize a simple and precise estimation of cellular networks financial feasibility. In other words, in cellular networks, while accurate path-loss estimation helps to achieve a reasonable cost, inaccurate path-loss estimation could either lead to reduce the cost but degrade the performance, or improve the performance but increase the cost. Thus accurate path loss estimation becomes a very crucial and desirable goal. To this end, different models were introduced in the literature for achieving the aforementioned goal; however, each model sought to be a valid choice in a specific environment. Therefore, our main objective in this paper was to provide an insight to the cellular network designers to simplify the decision-making process. A number of widely used path-loss estimation models that work in different environments, such as Free-space model, Two-ray model, Okumura/Hata model, COST 231 model, and Indoor model were reviewed and analyzed. This significantly would assist any cellular network designer to select an appropriate model according to its working environment, and thus realize the desirable accurate path-loss estimation. Matlab was used to perform this analysis. The analysis drove us to enter into implicit comparisons between the aforementioned models. Going through these comparisons, it is concluded that although an increase in the level of complexity is encountered when using models with large number of correction factors, more accurate path-loss estimation can be achieved.
Keywords: Cellular networks (CNs); Path-loss estimation models; Free space propagation model; Two-ray model; Okumura/Hata model; Cost 231 model; Indoor model
|17.||Ramalan Pelemahan Hujan di Malaysia Menggunakan Data TRMM
Noor Hidayah Tauhid Ahmad*, Asnor Nadirah Ishak, & Mandeep Singh Jit Singh
Hujan dilihat sebagai penyebab utama yang menyumbang kepada kemerosotan isyarat gelombang elektromagnetik bagi frekuensi melebihi 10GHz melalui proses resapan, dan penyelerakkan sehingga mengakibatkan isyarat menjadi lemah atau pudar. Perkhidmatan penyiaran satelit yang menggunakan frekuensi jalur Ku (12GHz hingga 18GHz) digunakan secara meluas telah menyebabkan kesesakan, maka jalur Ka digunakan untuk memenuhi permintaan pengguna. Namun, kesan pelemahan hujan terhadap jalur Ka adalah lebih tinggi berbanding jalur Ku. Dalam kajian ini, kesan pelemahan hujan bagi isyarat laluan menurun jalur Ka satelit Measat-5 dianalisis bagi melihat kesan pelemahan hujan dengan menggunakan data TRMM 3B42 untuk tempoh sebelas (11) tahun bermula Januari 2009 hingga Disember 2019 bagi empat belas (14) kawasan kajian. Data yang diperolehi seterusnya diproses bagi mendapatkan data hujan berintegrasi 1 minit menggunakan Model Segal bagi setiap kawasan kajian dan ramalan pelemahan hujan dilaksanakan menggunakan model dari ITU-R P.618-13. Hasil kajian ini merumuskan tiga (3) faktor utama yang mempengaruhi nilai pelemahan hujan iaitu nilai pelemahan spesifik, altitud kedudukan stesen penerima dan sudut dongak antena penerima isyarat satelit. Kesan pelemahan hujan terhadap tahap kebolehsediaan isyarat menunjukkan lapan (8) kawasan kajian adalah boleh menerima 99.90% kebolehsediaan isyarat, manakala selebihnya hanya boleh menerima 99.00% kebolehsediaan isyarat perkhidmatan bagi memenuhi keperluan ketidak bolehsediaan ITU. Secara keseluruhannya, nilai pelemahan hujan di Pantai Barat Semenanjung Malaysia adalah lebih kecil berbanding Pantai Timur Semenanjung Malaysia dan nilai pelemahan hujan di Pantai Timur Semenanjung Malaysia adalah menghampiri nilai pelemahan hujan di Sabah dan Sarawak.Abstract English
Rainfall is observed as a main contributing factor in the degradation of electromagnetic signal for frequency above 10GHz through absorption and scattering, resulting a weak or fading signal. Broadcasting satellite service operates in Ku band (12GHz to 18GHz) is widely used has caused congestion, therefore Ka band is exploited to meet the customer demand. However, the rain attenuation effects on Ka band are higher than Ku band. In this study, the rain attenuation effects of Ka band downlink signal of the Measat-5 satellite are analysed to assess the rain fade properties using TRMM 3B42 data for eleven (11) years from January 2009 until December 2019 for fourteen study areas. All data are processed to obtain 1-minute integration data using Segal Model and the prediction of rain attenuation are implemented using ITU-R P.618-13 model. This study summarizes, there are three, (3) main factors that influence the impact of rain attenuation, namely the value of specific attenuation, receiver station altitude and elevation angle of the satellite signal receiver antenna. The signal availability impact on rain attenuation shows, eight (8) study areas could receive 99.90% of service readiness, while the rest at 99.00% to comply with the ITU unavailability requirements. Overall, the value of rain attenuation on the West Coast of Peninsular Malaysia is smaller than the East Coast of Peninsular Malaysia and the value of rain attenuation in the East Coast of Peninsular Malaysia is closer to the value of rain attenuation in Sabah and Sarawak.
|18.||Initial Investigation on Binding Agents for Compact Powder Formulation from Rice (Bedak Sejuk)
Sim Siew Ping & Noorhisham Tan Kofli*
Bedak sejuk is a type of traditional cosmetic product that is favoured by women that possesses potential to be marketed as cosmetic product in the form of loose powder or compact powder. At present, there is no research available on the bedak sejuk in the compact format. Therefore, the main objective of this study is to produce a compact powder by introducing several binding agents. The soaking process of rice grain in the water was carried out for 84 days (14 days soaking interval, 6 times soaking water changed) to produce the paste of bedak sejuk. It was then dried and crushed using mortar and pestle before being sieved to be characterizes (particles sizes and bonds- FTIR). The compact format of bedak sejuk were prepared by addition of different binding agents namely ethanol, isopropyl alcohol, polyvinyl alcohol(PVA), magnesium stearate and jojoba oil to evaluate its cracking level, hardness through drop test and easiness of application onto the skin. Based on the result, the particle size of uncrushed and crushed bedak sejuk were at 1000-2000μm and ranging 150-250 μm respectively. The FTIR analysis showed that the functional groups existed in bedak sejuk were OH bond, C-H bond, C=O bond, C-O-H bond and C-O bond. Each type of compact bedak sejuk produced from each binding agent exhibits their own strengths and weaknesses respectively. In short, alcohol (PVA) is found to be the best binding agent used due to its easiness to be applied onto the skin.
Keywords: Bedak sejuk; fermentation; binding agent; drop test; compact powder
|19.||Dynamic Analytical Modeling of Horizontal Outline Turn of T-Girder Simply Supported Bridge
Ali Fadhil Naser*
Layout line of bridge structure is a direction line which is used to define the horizontal and vertical alignment of the bridge structure. The objective of this study is to evaluate and optimize the different designs of bridge horizontal outline turn and compare the results with horizontal layout straight of bridge using dynamic analysis according to finite element analysis method. Dynamic analysis results showed that most models have converging values of dynamic natural frequency except Model No. F. and it explains that the higher rate of natural frequency is 5.10Hz within model No. F. The maximum value of loaded frequency is equal to 6.35 Hz for model No. I (Straight – curve right – straight – curve left – straight). Model No. A appears minimum value of loaded frequency which equal to 3.56Hz. The higher value of loaded frequency indicates that the bridge model has high vibration state which effects on the stiffness and flexibility of bridge structure. Model No. I appears higher value of downward acceleration which is 3.55m/s2. The maximum value of upward and downward deflection is 1.84mm and 4.07mm respectively in model No. G, indicating that this model will easy to deflect under traffic loads. It can be concluded that The bridges models No. F, H, I have values of loaded frequency higher than the values of natural frequency. Therefore, these models have lower stiffness and flexibility and bearing capacity than other. Therefore, this study recommended that the optimum design which has high stiffness and more elasticity.
Keywords: Horizontal outline; T-girder; bridge; finite element; dynamic; loaded frequency
|20.||Comparative Modelling of Strength Properties of Hydrated-Lime Activated Rice- Husk-Ash (HARHA) Modified Soft Soil for Pavement Construction Purposes by Artificial Neural Network (ANN) and Fuzzy Logic (FL)
Onyelowe, K. C.*, Alaneme, G. U., Onyia, M. E.b, Bui Van, D., Dimonyeka, M. U., Nnadi E.a, Ogbonna, C., Odum, L. O.d, Aju, D. E., Abel, C.e, Udousoro I. M. & Onukwugha, E.
Artificial neural network and fuzzy logic based model soft-computing techniques were adapted in the research study for the evaluation of the expansive clay soil-HARHA mixture’s consistency limit, compressibility and mechanical strength properties. The problematic clay soil was stabilized with varying proportions of HARHA (stabilizing agent) which is an agricultural waste derivative from the milling of rice ranging from 0% to 12%; the utilization of the alkaline activated wastes encourages its recycling and re-use to obtain sustainable, eco-efficient and eco-friendly engineered infrastructure for use in the construction industry with economic benefits also. The obtained laboratory and experimental responses were taken as the system database for the ANN and fuzzy logic model development; the soil-HARHA proportions with their corresponding compaction and consistency limit characteristics were feed to the network as the model input variables while the mechanical strength (California-bearing-ratio (CBR), unconfined-compressive-strength (UCS) and Resistance value (R-values)) responses of the blended soil mixture were the model target variables. For the ANN model, feed forward back propagation and Levernberg Marquardt training algorithm were utilized for the model development with the optimized network architecture of 8-6-3 derived based on MSE performance criteria; while for the fuzzy logic model, the mamdani FIS with both triangular and trapezoidal membership function with both models formulated, simulated and computed using MATLAB toolbox. The models were compared in terms of accuracy of prediction using MAE, RMSE and coefficient of determination and from the computed results, 0.2750, 0.4154 and 0.9983 respectively for ANN model while 0.3737, 0.6654 and 0.9894 respectively was obtained for fuzzy logic model. The two models displayed robust characteristics and performed satisfactorily enabling the optimization of the solid waste derivatives utilization for soil mechanical properties improvement for engineering purposes.
Keywords: California bearing ratio (CBR); Unconfined compressive strength (UCS); Resistance value (R-V); Activated rice-husk-ash; Soil stabilization; Fuzzy logic (FL); Artificial neural networks (ANN); hydrated-lime; soil strength properties