Universiti Putra Malaysia
Download Latest Complete Journal - JST Vol. 25 (S) Jul. 2017
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1
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(Downloads: 12)
Abstract (Viewed: 1)Agarwood or gaharu, due to its unique scent and quality is considered one of the most expensive wood in the world. This paper uses solvent trap, Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) to establish agarwood quality, and is part of ongoing research. The result showed that monoterpenes hydrocarbon, sesquiterpenes hydrocarbon and oxygenated sesquiterpene contribute to agarwood smoke. Among many compounds extracted, 2-hydrdoxy-benzaldehyde, β- selinene and guaia-1(10),11-dien-15,2-olide were found dominant in monoterpenes hydrocarbon, sesquiterpenes hydrocarbon and oxygenated sesquiterpenes respectively. This finding pointed to the utility of solvent trap in extracting chemical compounds of agarwood smoke. This study is also useful for further research on establishing the grade of agarwood. Agarwood, GC-FID, GC-MS, Quality, solvent trap
2
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(Downloads: 10)
Abstract (Viewed: 2)The objective of this study is to elucidate sorption mechanism of ammonia-N by Spent Mushroom Substrate Biochar (SMSB), produced from pyrolysis process of Spent Mushroom Substrate (SMS) at 550°C for two hours. Surface functional group, ash contents, and elemental compositions were analysed using Boehm titration, furnace and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) respectively. Sorption parameters (i.e., sorbent dosage, input ammonia-N concentration, and contact time) were optimised, and the sorption data were analysed using kinetic models (i.e., pseudo-first-order and pseudo-second-order), and isotherm models (i.e., Langmuir, Freundlich, and Dubinin-Radushkevich (D-R)). The surface of SMSB consists of carboxylic (0.3 mmol/g), phenolic (0.5 mmol/g), and basic functional groups (0.2 mmol/g). Sorption of ammonia-N was best described by the pseudo-second-order kinetic model and the Dubinin-Radushkevich (D-R) isotherm model. The D-R sorption capacity for SMSB was 12.6 mg/g, and correlates well with the amount of acid functional groups (i.e., carboxylic and phenolic groups) in SMSB (i.e., 14.4 mg/g). The low Freundlich constant (n = 0.754), and low D-R mean free energy per mol of the adsorbate (E = 4.4 kJ/mol) indicates a physical sorption process, and ammonia-N binds with acid functional groups through weak forces. The result shows great potential of SMSB for removing ammonia-N in wastewater. Activated carbon, ammonia, ammonium, charcoal, nutrient, sewage wastewater
3
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(Downloads: 6)
Abstract (Viewed: 1)This study describes the adaptations of diatoms, Cylindrotheca fusiformis and other marine diatoms, in a new formulated enriched medium Tris-phosphate seawater (TP-SW). The medium was designed to maintain long-term cultures of wide-range marine diatoms in laboratory that produces high biomass of cultures. The diatoms were adapted and cultivated in the medium for 15 days and the number of cells was recorded daily. It was found that the number of cells declined after two weeks indicating death phase of the cells. This indicates that the TP-SW medium has supported the growth of diatoms during the period and can be used to cultivate diatoms in vitro. Studies on the TP-SW medium must be done to obtain optimal medium that can provide not only a conducive environment for the survival of diatoms but also high biomass production. Adaptation, diatoms, enriched medium, growth, nutrient
4
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(Downloads: 12)
Abstract (Viewed: 1)This study examines the effect of a low glycaemic index (LGI) intervention to improve dietary intake among women with Gestational Diabetes Mellitus (GDM). Women with GDM were randomised to receive either a low GI intervention (LGI; n = 20) or standard nutrition therapy (SNT; n = 20) for a 4-week period. Food Frequency Questionnaire (FFQ) and Three-Day Diet Record assessed the dietary intake and food choices. Dietary intake and food choices of the participants were comparable at baseline. At the end of the study, energy, protein, fat and carbohydrate were reduced in both groups (p ± 0.05). In the LGI group, fibre and calcium intake was higher compared with SNT group. More participants in the LGI group consumed rice from the low GI varieties, the whole grain breads and the low GI biscuits (p<0.05) compared with participants in the SNT group. The diet GI reduced significantly in the LGI group (50 ± 9 units) compared with the SNT group (57 ± 6) (p ± 0.05). Findings showed low GI dietary intervention improved the dietary intake of women with GDM. Carbohydrate, dietary intake, Gestational Diabetes Mellitus, low glycaemic index
5
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(Downloads: 10)
Abstract (Viewed: 1)In an earlier study, a three-fingered robot hand was developed for assembly work. Proportional Integral Derivative (PID) control was used to control the position of a DC micromotor measured by an encoder. However, PID control alone could not cater the nonlinearities due to friction of gears and varying loads applied to the finger. Therefore, in order to develop an intelligent control algorithm in future, the effects of varying PID gains need to be investigated to distinguish the optimal value that could produce the best transient response performance. This paper discusses the effect of varying PID gains on position transient response of the joint motor of robot hand through real-time experiments. Several ranges of KP, KI and KD were identified based on the required transient response parameters such as percentage overshoot (%OS), settling time (TS) of within 2%, steady state error (SSE) and rise time (TR). The gains are tuned across the range by a fixed interval with the tuning order starting from KP, KI and KD. It can be observed that the suitable ranges of PID are 0.3 to 0.5 for KP, 1.15 to 1.45 for KI and 0.10 to 0.14 for KD. Meanwhile, the optimum value of 0.4, 1.45 and 0.10 for KP, KI and KD respectively is found to produce 0 of % OS, 5.09 sec of TS and 2.48 sec of TR. Hence, the gains can be applied to the development of an improved position control using intelligent method for the robot hand in future works. PID control, PID parameter tuning, position control, transient response, real-time experiment
6
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(Downloads: 9)
Abstract (Viewed: 1)Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) has been recognised as an effective technique to analyse car paint. This study was conducted to assess the combination of Py-GC-MS and chemometric techniques to classify car paint primer, the inner layer of car paint system. Fifty car paint primer samples from various manufacturers were analysed using Py-GC-MS, and data set of identified pyrolysis products was subjected to principal component analysis (PCA) and discriminant analysis (DA). The PCA rendered 16 principal components with 86.33% of the total variance. The DA was useful to classify the car paint primer samples according to their types (1k and 2k primer) with 100% correct classification in the test set for all three modes (standard, stepwise forward and stepwise backward). Three compounds, indolizine, 1,3-benzenedicarbonitrile and p-terphenyl, were the most significant compounds in discriminating the car paint primer samples. Car paint primer, chemometric analysis, Py-GC-MS
7
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(Downloads: 6)
Abstract (Viewed: 2)The present study examines the interaction between concrete and steel plate, particularly on the load bearing capacity of concrete blocks under confinement effects. 12 concrete blocks with the dimensions of 200 mm × 200 mm in cross section and 200 mm high were tested up to failure under compression load through 10 mm thickness of steel bearing plate. A series of experimental testing were performed to determine the maximum load bearing capacity in different sizes of steel plate and to identify the possible failure modes. The experimental data obtained from the experimental investigations were compared with pre-existing experimental data obtained from literature and mathematical formulation in various international standards. Experimental results indicate that the use of larger bearing plate gave higher value of load bearing capacity compared with small bearing plate due to larger contact area, thus, resulting in better effect of confinement. It was found that the concrete blocks fail in the shape of inverse pyramid when the steel plate is placed on top of it. Besides, other failures are vertical cracks and splitting cracks which appeared at the outer edge of contact area. Bearing strength, concrete block, confinement effects, steel bearing plate
8
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(Downloads: 9)
Abstract (Viewed: 1)Displacement ventilation (DV) has been found to be effective in cooling large indoor spaces, but its effectiveness in providing thermal comfort in tropical buildings requires more detailed analysis to be made. This study examines the thermal environment in a lecture hall cooled via DV using FloEFD, a computational fluid dynamics (CFD) software. A calibrated CFD simulation model was developed to replicate the actual atmospheric conditions of the DV-cooled lecture hall. Results indicate that some parts of the hall received more cooling and air movement than required which would result in local thermal discomfort, especially at the front seating areas. The CFD results were consistent with those of earlier studies which validated the simulation model. The findings can be used to determine the locations which are more prone to steep thermal gradients in addition to reducing thermal discomfort, which include suitable arrangements of occupants in the lecture hall when it is not fully occupied and resetting the diffusers' supply air temperature. Computational fluid dynamics (CFD), Displacement ventilation (DV), lecture hall, thermal comfort, thermal environment
9
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(Downloads: 9)
Abstract (Viewed: 1)NiTi is well known for its shape memory effect and super elasticity (SE), and is widely used in medical, dentistry and aerospace applications. For shape memory, NiTi has the ability to undergo deformation at certain temperature then recover to its original shape while SE occurs at narrow temperature range just above its transformation temperature. It shows that this material remembers its original shape and is elastic under stress. The application of nitinol as partial replacement in reinforced concrete beam for seismic resistant structures is popular due to it re-centring capability and distinctive properties. Using Shape Memory Alloy (SMA) in structures has its downsides. Hence, hybrid reinforced concrete beam with SMA was introduced to improve the structure's ductility and energy dissipation. Hence, this research is aimed at distinguishing microstructure and mechanical properties of SMA and steel rebar. Not much is known about how SMA behaves when subjected to compression. Therefore, X-Ray Diffraction (XRD) was used to analyse if any secondary phase exists and Differential Scanning Calorimetry (DSC) test was used to analyse the phase transformation. The results showed hybrid NiTi-steel rebar can address some deficiencies of NiTi and in terms of costs. On the other hand, combining them will result in super elastic recovery, displacement ductility and strength capacity for seismic resistant design. Hybrid NiTi, shape memory alloy, shape memory effect (SME), superelasticity (SE)
10
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(Downloads: 7)
Abstract (Viewed: 1)Food waste is a mixture of organic residues that affect fermentation process. Thus, appropriate parameters should be optimised to ensure high biomethane production. In this research, response surface methodology (RSM) was utilised for building models, evaluating the significance of several independent factors (pH, temperature, substrate concentration and inocula size) and determining optimum conditions for desirable responses (biomethane yield). The RSM and contour plots set the optimum working factors in order to accomplish the desired biomethane yield. Results suggest that biomethane yield can be increased when pH and temperature are increased. Thus, the main effects of parameters are pH and temperature. Anaerobic digestion, biomethane yield, response surface methodology
11
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(Downloads: 7)
Abstract (Viewed: 2)A prototype of three-fingered robot hand was very rigid in its motion, and prone to damages when dealing with hard surfaces or when subjected to external environmental forces. The robot hand could damage fragile objects during grasping tasks if a position control alone is used. Therefore, this study proposes application of force control to the robot hand to improve its current grasping capabilities. Impedance control that considers the dynamic of the robot to produce the softness like human hand was implemented in this study. The dynamical behaviour of the robot hand strongly depends on the impedance parameters known as virtual mass, damping and stiffness. Therefore, the optimal values of impedance parameters need to be investigated to develop a position-based impedance control for the robot finger. Hence, the objective of this study is to determine the optimal value of impedance parameters to impose desired dynamics to the robot system. A constant force weighing 100 g was used by implementing varying impedance parameters to the tip-end's position. Three experiments were conducted: first to decide the order of parameters to be adjusted, then to determine the optimal value of impedance parameters, and finally to test the optimal values with random force applied to the robot finger. The determined optimal values are: stiffness=1000, damping=10 and mass=1. Thus, the combined parameters have proven that the modified position is capable of responding according to the exerted contact force. Dynamic behaviour, impedance control, impedance parameters, robot finger
12
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(Downloads: 8)
Abstract (Viewed: 2)This paper looks at electrical power generation from solar concentrator using thermoelectric generator. An experiment was conducted on a concentrator thermoelectric generator (CTEG) utilising solar thermal energy. The CTEG used a parabolic dish as concentrator with thermoelectric device installed at the focal point to convert thermal energy to generate electricity. The investigation covered the cooling effect of the cold side of the thermoelectric generator using natural and forced convection cooling for optimum output. Forced convection cooling with a fan provided 69% more power output from the CTEG system as the temperature difference across the TEG was greater than the system cooled by natural convection. The outcome of this project showed maximum power output was obtained for the CTEG system cooled by forced convection cooling. Concentrated solar energy, forced convection, thermoelectric generator, thermal energy
13
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(Downloads: 5)
Abstract (Viewed: 1)In this paper, a micropropagation protocol of sugar palm (Arenga pinnata Wurmb Merr) through callogenesis and somatic embryogenesis was examined. Callus induction frequency and somatic embryogenesis response were dependent on plant growth regulators (PGRs) and genotype. Semi-compact and compact embryogenic calluses were induced from excised immature zygotic embryo (IZE) cultured on semi-solid MS (Murashige & Skoog, 1962) medium supplemented with various concentration and combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyl aminopurine acid (BAP). MS medium supplemented with 0.4 mg/L 2,4-D and 0.5 mg/L BAP was found optimum to induce 100% rate of embryogenic calluses and maximum degree of callus formation after 8 and 12 weeks of culture. The incorporation of increased sucrose concentration (60.0 g/L) and 2.0 g/L casein hydrolysate (CH) to the culture medium with similar PGRs composition enhanced the induction of globular somatic embryos (SEs), while addition of silver nitrate (AgNO3) produced SEs of different stages. SEs maturated in MS medium containing 1.0 mg/L BAP and 1.0 mg/L naphthalene-acetic acid (NAA) formed cotyledon-stage embryos. Clonal roots regeneration was obtained on half-strength MS devoid of PGRs after 4 months of culture. Frequent subcultures increased embryogenesis rate favourably. Embryogenic callus induction, immature zygotic embryo (IZE), plant growth regulators (PGRs), somatic embryogenesis, sugar palm
14
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(Downloads: 7)
Abstract (Viewed: 1)A new smart grid system is widely used for energy supply system because it is simple, available, low cost, high efficiency and environmentally friendly. Conventionally, inverter techniques are utilised to convert input DC into output AC with the same frequency and phase. This process suffers the same problem which is a higher harmonic distortion, phase synchronisation, lower quality of waveform and long distance, among others. In this paper, three phase synchronous inverters (PSI) were used to direct synchronous PWM control, LCL filter, three phase RLC load, three phase Yg-Delta transformer, 5 km feeder with 2 MW load. PWM was used to generate the pulse signal for synchronisation. However, LCL filters were used to remove the noise in inverter output and transformer output side of the design. A balanced three phase load (10 kVAR) and also the input DC voltage 500 V were considered in this design. Three phase transformer (100kVA/260V/25kV) was used to increase the inverter output voltage and current with the fundamental frequency (50 Hz). The system conversion efficiency was 99.96% and phase synchronous error for each phase was approximately 4.5 degrees. Choke coil, controller, LCL filter, PSI, transformer
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(Downloads: 8)
Abstract (Viewed: 2)In this study, residual oil from oil palm decanter cake (OPDC) was recovered using n-hexane through Soxhlet extraction process. The residual oil recovered was analysed for its physical and chemical properties. The oil content, moisture, Free Fatty Acid (FFA), Peroxide Value (PV), Iodine Value (IV), Deterioration of Bleachability Index (DOBI) and carotene were measured as 15.43±0.45% (dry), 70.96±0.14%, 6.42±0.11%, 4.37±0.04 meq/kg, 53.28±0.02 g/100 g, 1.93±0.03 and 833.20±39 ppm respectively. The results showed that its fatty acid composition, carotene and IV were comparable with the Malaysian Palm Oil Board (MPOB) standard for crude palm oil (CPO), whilst the properties of the other value had slightly exceeded due to oxidation during the extraction process. Carotene, crude palm oil (CPO), oil palm decanter cake (OPDC), physico-chemical properties, Soxhlet extraction
16
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(Downloads: 7)
Abstract (Viewed: 1)Patient satisfaction plays a crucial role in assessing the quality of services provided by healthcare services. The purpose of the present study was to determine the factors influencing patient satisfaction towards services of a specialist medical centre. A cross sectional study was conducted among 300 patients attending a semi-private multidisciplinary specialist centre in Malaysia. They were provided with a set of self-administered questionnaires on patient satisfaction with the services received at the facility. Patient satisfaction was divided into three main components: patient characteristics, delivery of services and hospital characteristics. Additional qualitative comments were also obtained. The mainstay of the analysis was multivariate logistic regression. Altogether, 273 (91.2%) of the patients rated their overall satisfaction as "good" or "very good". Hospital characteristics (i.e., cleanliness; OR: 30.58 (95% CI: 3.52 – 265.79), hospital appearance; OR: 12.69 (95% CI; 1.51 – 106.53) had the strongest influence on the patient's overall satisfaction. The findings revealed that the reason a majority of patients liked the hospital was related to good quality of services (18.7%), comfort (21.9%) and the friendly staff (8.8%). Hence, hospital characteristics are the most important determinants of overall patient satisfaction. In addition, the quality of delivery services and a friendly staff should also be considered when improving hospital services in a multidisciplinary specialist centre. Hospital characteristics, patient satisfaction, quality of services, specialist centre
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(Downloads: 8)
Abstract (Viewed: 1)Fuzzy Logic is a popular method to tune a PID controller. By using Fuzzy Logic, the PID is tuned automatically based on information of output error, which is better than other tuning rule methods. Fuzzy Logic Control will tune gains of PID controller by using a set of fuzzy rules designed specifically for that. However, specific transient requirements of the process output cannot be assigned to the controller. This research proposes a new method to overcome this problem by using a reference model. Step input from the reference model that contains the desired response information will be compared against the actual output. The reference model can be pre-selected by the user as desired. This study was simulated on a steam temperature process model while few sets of first-order model were used as reference. The results showed that the proposed Fuzzy PID controller with reference model provides better performance with perfect tracking during transient and steady-state. Component, PID controller, Reference model, Self-tuning fuzzy control, Steam temperature control
18
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(Downloads: 10)
Abstract (Viewed: 1)In this study, the new compound of thiourea derivatives were successfully synthesized, namely N-((3-chlorophenyl) carbamothioyl) benzamide (T1) and N-((4-chlorophenyl) carbamothioyl) benzamide (T2). These series of thiourea compounds were prepared from the reaction of benzoyl chloride with ammonium thiocyanate to produce benzoyl isothiocyanate, then direct reaction with amines by using condensation method. Their structures were characterized on the basis elemental analysis and spectroscopic techniques namely infrared and nuclear magnetic resonance. The Infrared spectra showed the significant results of stretching vibrations of the compounds are ?(C=O), ?(C=S) and ?(C-N) at 1533.39-1671.00 cm-1, 1256.64-1261.73 cm-1 and 1144.22-1144.81 cm-1, respectively. These compounds were investigated as corrosion inhibitors on mild steel in 1M H2SO4 using linear polarization techniques. Results show the highest inhibition efficiency of T1 is 55% while for T2 is 73%. The percentage inhibition efficiency of T2 is higher than T1 due to the difference position of substituent at meta and para. Corrosion inhibition, linear polarization, mild steel, thiourea
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(Downloads: 9)
Abstract (Viewed: 2)Electrocoagulation has proven to be an effective method in the treatment of wastewater. This study evaluated the decolourisation of Palm Oil Mill Effluent (POME) using electrocoagulation (EC) batch reactor by utilising aluminium as sacrificial electrode. POME sample source from a final discharged pond at a palm oil mill was characterised for its colour, chemical oxygen demand (COD), pH, conductivity and turbidity; were found to be 2707 PtCo, 3909 mg/L, 7.63, 12.82 mS/cm and 755 NTU respectively. The respective effects of operating parameters such as pH (3 to 11), applied voltage (5 V to 20 V), plate gap (7.5 to 11.5 cm) and operating time (1 to 8 hours) were investigated. The decolourisation of POME was observed to increase with increasing voltage and operating time. Highest removal efficiency was observed at pH 5, 20 V applied voltage, 9.5 cm plate gap and at 8-hour operating time with colour removal efficiency of 89, 79, 78 and 64% respectively. From the findings, it can be concluded that electrocoagulation process using aluminium electrodes is a reliable technique for the removal of colour from POME. Aluminium electrode, effluent, electrocoagulation, POME
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(Downloads: 10)
Abstract (Viewed: 2)Rainfall is one of the microclimatic variables that vary with space. The changes in vegetation characteristics may influence the microclimate elements. To demonstrate rainfall variation due to vegetation, the relationship between rainfall and vegetation should be spatially investigated over a local scale. This paper aims to explore the impact of vegetation on local variations of rainfall based on Geographically Weighted Regression (GWR) approach. The global and local relationship between rainfall and the extracted Normalized Difference Vegetation Index (NDVI) of Landsat 7 ETM+ are quantitatively estimated in 2000 and 2011 within the northern and east coast regions of the Peninsular Malaysia. Based on 277 rainfall stations, the Moran's Index (Moran's I) spatial autocorrelation and Ordinary Least Square (OLS) - GWR methods were applied to analyse the rainfall spatial patterns and to determine rainfall spatial variation, respectively. It was found that, the rainfall spatial patterns exhibit small clustering patterns which leads to non-stationarity. This indicator supports the use of local regression approach in exploring the variation of rainfall due to vegetation. The R-Squared (R2) from GWR (0.51 and 0.75) significantly improved the R2 from OLS (0.01 and 0.04) for both years. The approach of GWR in the relationship between rainfall and vegetation provides findings on rainfall spatial variation on a local scale. GWR, Moran's I spatial autocorrelation, NDVI, OLS, rainfall spatial variation
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(Downloads: 8)
Abstract (Viewed: 1)This paper details a study conducted to evaluate the performance of cold in-place recycling (CIPR) using polymer modified asphalt emulsion (PMAE). The asphalt emulsion was modified using natural rubber latex (NRL). Four proportions of reclaimed asphalt pavement (RAP) which are 0%, 25%, 50% and 75% were mixed with natural aggregates and modified asphalt emulsion using natural rubber latex (NRL). The results showed that the optimum modified asphalt emulsion for each proportion of RAP decreased due to the increase in RAP content. Results obtained from Indirect Tensile Strength (ITS) and Uniaxial Compressive Strength (UCS) test for the mixes complied with the requirements of the Road Engineering Association of Malaysia (REAM) specifications. The unsoaked and soaked ITS values obtained were 0.2 MPa and 0.15 MPa respectively, and the minimum compressive strength of CIPR mix obtained was 0.7 MPa. Based on the evaluation of performance for the four RAP proportions, it was determined that 50% of RAP gave the best combination of the CIPR mixture. Cold-in-place recycling, natural rubber latex, polymer modified asphalt emulsion, reclaimed asphalt pavement
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(Downloads: 7)
Abstract (Viewed: 1)Ventilation is the process of exchanging air in a closed space to provide good indoor air quality. Computational Fluid Dynamics (CFD) has become one of the most important and reliable tools to assess natural ventilation. This paper presents the effect of wind direction on temperature and velocity inside a building with outlet windows at leeward wall and side wall. The CFD simulation was performed using Reynolds-Average Navier-Stoke (RANS) approach with k-ε model. The selection of standard k-ε model is due to suitability of this model to perform the wind speed profile and temperature profile inside the building. Validation of cross-ventilation is performed based on earlier Particular Image Velocimetry (PIV) measurements and shows very minimal discrepancy between CFD and PIV result. The result of velocity and temperature shows that the wind speed and temperature inside a building strongly depends on the incident winds angle and outlet opening of the building. CFD, outflow position, temperature, velocity, wind direction
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(Downloads: 6)
Abstract (Viewed: 1)The study aims to investigate the effect of injection moulding parameters on plastic flows behaviour of the multiple-cavity polyethylene terephthalate (PET) cylindrical containers via injection moulding process. The motivation of this study is to present an alternative manufacturing solution to make cylindrical type containers that are commonly used in packaging beverages, such as the 330 ml standard size for packaging carbonated soft drink. The PET cylindrical container was modelled using CATIA drawing software and the injection moulding simulation process was done via Moldflow software. The investigation was done by varying two significant moulding parameters; the material melt temperature and the mould temperature. The effects of these two parameters on the PET plastic flow behaviour were studied. In particular, the simulations of the model were analysed and focused on the mould filling time as well as the moulded PET cylindrical container's shrinkage occurrence. Three types of mould cavities structure were understudied; single-cavity, four-cavity and eight-cavity. Results show that the eight-cavity mould yielded higher production rate. The simulation results indicated that the production rate of 4-cavity and 8-cavity mould increased by 258.5% and 578.8% respectively. It was observed by increasing the melting temperature, the mould filling time is shorter and as a result, the production rate has increased by 7.75% per °C. But with this Mouldflow setting, the volumetric shrinkage and the maximum deflection have been significantly affected; increased by 23.15% and 29.26% respectively. The mould filling time and maximum deflection did not show a steady trend line however, the volumetric shrinkage increased by 7.28% per °C. Injection moulding, mould filling time, moulding parameters, polyethylene terephthalate, shrinkage
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Abstract (Viewed: 3)The aims of this study are to estimate the equivalent dose to the skin, eyes and thyroid in intra- and extra-oral imaging examination and to compare the dose-area product (DAP) derived from the calculation method with Diagnostic Reference Levels (DRL) that has been provided by the Malaysian Ministry of Health (MOH). Dose equivalent is measured by placing Thermoluminescence Dosimeter (TLD-100H) in the anthropomorphic RANDO phantom. Exposure is performed using intra-oral X-ray machine ActeonSatelec X-Mind® and extra-oral X-ray machine InstrumentariumOP300®, and the value is compared to the equivalent dose of the International Commission on Radiological Protection (ICRP) dose limit. DAP value for both examinations was obtained by using formula and comparing them with the DRL from MOH. The average dose equivalent of intra- and extra-oral radiographic examination is lower than the ICRP dose limit. The doses derived from both examinations did not exceed the prescribed levels when compared with DRL. The doses calculated for intra-oral examination of molar maxillary, molar mandibular and interproximal (bitewing) was 0.880 mGy while periapical examination of the anterior maxillary and mandibular was 0.688 mGy and occlusal examination was 1.100 mGy. For the panoramic examination the dose was 0.011 mGy.m2 while lateral cephalometric examination was 0.0054 mGy.m2. The doses obtained from this study were within the dose limit and predetermined level. This shows that a patient receives the minimum dose for both dental radiographic examinations with the optimum level of safety which meets the ALARA concept. Dental imaging, diagnostic reference levels, dose-area product, equivalent dose
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(Downloads: 5)
Abstract (Viewed: 1)Human umbilical vein endothelial cells (HUVECs) were cultured on microcarrier beads to accommodate different experiment apparatus such as rotating wall vessel. In this study, fluid operating apparatus (FPA) was used. However, the effect of inflammation and endothelial activation biomarkers in HUVECs cultured on different culture surface and containers are not well established. The effects of temperature changes on these biomarkers in HUVECs grown in FPA, a spaceflight hardware, are still unclear. The objective of this study was to compare the protein and gene expression of inflammation and endothelial activation biomarkers in (i) HUVECs cultured on microcarrier beads in conventional culture flask (CCFMC) vs. conventional culture flask (CCF) (ii) HUVECs cultured on microcarrier in FPA (FPAMC) vs. CCFMC and (iii) HUVEC cultured in FPAMC with ideal temperature (37°C) (FPAMC) vs. simulated space travel temperature(25-37°C), (FPAMC-ST). sICAM-1 and sVCAM-1protein expression in HUVECs grown in CCFMC were higher than CCF. FPAMC had higher IL-6, TNF-α, ICAM-1, VCAM-1, e-selectin, NF?B and eNOS gene expression than in CCFMC. FPAMC-ST had higher ICAM-1 and e-selectin protein expression than FPAMC- in ideal temperature. HUVECs are cultured onto microcarrier in simulated space flight temperature compared with ideal temperature had higher protein expression of sICAM-1 and e-selectin but the protein and gene expression of other biomarkers of inflammation and endothelial activation are comparable. This suggests that differences in culture surface and container are have an impact on the expression of inflammation and adhesion molecule by HUVECs. Adhesion molecules, endothelial cells, fluid processing apparatus (FPA), inflammation, microcarrier beads
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(Downloads: 5)
Abstract (Viewed: 1)Familial hypercholesterolaemia (FH) is an autosomal dominant genetic disorder characterised by severe hypercholesterolaemia leading to premature coronary artery disease (CAD). Oxidised low-density lipoprotein (ox-LDL), F2-isoprostanes (ISP) and malondialdehyde (MDA) are established oxidative stress biomarker, but the status of oxidative stress in FH is not well studied. The aim of this study is to investigate oxidative stress status among FH patients and normocholesterolaemic control (NC) subjects. Ninety-eight FH patients and 100 (age, gender and BMI matched) NC subjects were recruited in series of health screening programmes across the country. Fasting blood samples were analysed for serum ox-LDL, ISP and MDA. Ox-LDL, ISP and MDA concentrations were higher in FH groups compared to NC (mean±SEM: 63.0±6.5 vs 25.5±1.2 (U/l), p<0.001); 749.7±74.0 vs 354.2±18.1 pg/ml, p<0.0001; 342.4±46.0 vs 162.7±13.5 nmol/g, p<0.0001). Ox-LDL showed correlation with glucose (p<0.05), TC (p<0.001), LDL-c (p<0.001) and HDL-c (p<0.01) in all subjects. LDL-c was associated positively with ox-LDL concentration (p<0.001). LDL-c was an independent predictor for ox-LDL concentration (p<0.001) after adjustment for the various confounding factors. In conclusion, FH patients have higher oxidative stress status which contributes to the greater risk of developing atherosclerosis and its related complications. LDL concentration is an independent determinant of ox-LDL, suggesting that both the proatherogenic quantity and quality of LDL coexist in FH which enhance the risk of premature CAD. Familial hypercholesterolaemia, atherosclerosis, F2-isoprostanes, malondialdehyde, oxidised low-density lipoprotein
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(Downloads: 6)
Abstract (Viewed: 1)Safe level of daylighting for artefact conservation in historic buildings is a difficult task to achieve. Previous studies indicated that lighting problems in historic museum galleries were mainly due to unshaded walls that allowed direct sun penetration over the display areas. Ceiling geometry can also affect the daylighting performance significantly, particularly on the interior distribution of light. Malaysia, with hot and humid climate, and tropical sky conditions receives plenty of natural light all year around. The fluxes in natural lighting exposures confirm the need for strategic daylight control programme in the exhibition gallery. The study aims to assess the ceiling geometry contribution for four orientations; North, East, South and West through computer simulations. The research approach was based on comparisons between pitched and flat ceiling simulation output data. Further comparisons were performed with the recommended lighting limits for conservation of artefacts. The comparisons allowed better understanding of light damage issues and highlight the control of daylighting distributions through realistic predictive images and ceiling geometry designs. The results showed that the types of exhibits materials and its placement are affected by the ceiling geometry and constant changes in natural lighting exposure. The study confirms that ceiling geometry can act as a control mechanism with the environment physical features as part of preventive conservation criteria in the exhibition gallery. Thus, a systematic light-monitoring programme in the exhibition gallery is necessary to control illuminance level and cumulative exposure limits, for artefact preservation. Ceiling geometry, daylighting performance, historic building, tropical sky
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Abstract (Viewed: 1)This paper presents a study on the effect of Arenga pinnata fibre volume fraction on the tensile and compressive properties of Arenga pinnata fibre reinforced epoxy composite (APREC). The composites were produced using four different Arenga pinnata fibre volume contents, which were 10vol%, 15vol%, 20vol%, and 25vol%, in unidirectional (UD) fibre alignment. Tensile and compression tests were performed on all APREC specimens in order to investigate the effect of fibre volume fraction on modulus of elasticity, strength and strain to failure. The morphological structure of fractured specimens was observed using scanning electron microscopy (SEM) in order to evaluate the fracture mechanisms involved when the specimens were subjected to tensile or compressive loading. The results indicated that the higher the amount of Arenga pinnata fibres, the higher the stiffness of the composites. This is shown by the increment of tensile and compressive modulus of the specimens when the fibre volume content was increased. Tensile modulus increased up to 180% when 25vol% Arenga pinnata fibre was used in APREC compared to Pure Epoxy specimen. It can also be observed that the tensile strength of the specimens increased 28% from 53.820 MPa (for Pure Epoxy) to 68.692 MPa (for Epoxy with 25vol% APREC addition). Meanwhile, compressive modulus and strength increased up to 3.24% and 9.17%, respectively. These results suggest that the addition of Arenga pinnata fibres significantly improved the tensile and compressive properties of APREC. Arenga pinnata, compressive, tensile, fibre volume fraction, unidirectional fibre alignment
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Abstract (Viewed: 1)The effects of hole size on open hole tensile properties of Kevlar-glass fibre hybrid composite laminates were thoroughly investigated in this work. Woven Kevlar/glass fibre epoxy composite laminates were fabricated using hand lay-up and vacuum bagging technique. Specimens of five different hole size (1 mm, 4 mm, 6 mm, 8 mm and 12 mm) were carefully prepared before the tensile test was performed according to ASTM D5766. Results indicated that hybridizing Kevlar to glass fibres improved tensile strength and failure strain of hybrid composite specimen. In addition, increasing the hole size reduced strength retention of the hybrid specimen from 96% for 1 mm hole size to 62% and 44% for 6 mm and 12 mm, respectively. Fractography analysis showed that several types of failure mechanisms were observed such as brittle failure, ductile failure, fibre breakage, delamination and fibre-matrix splitting. It is concluded that as hole size increased, failure behaviour changed from a matrix dominated failure mode to a fibre-dominated failure mode. Glass fibre, hole size, hybrid composites, Kevlar fibre, open hole tensile

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