ORCID Profile
0000-0001-8715-3314
Current Organisations
National University of Malaysia
,
Sultan Qaboos University
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Publisher: Springer Science and Business Media LLC
Date: 06-2016
Publisher: Canadian Center of Science and Education
Date: 24-05-2013
DOI: 10.5539/IES.V6N6P137
Publisher: Impact Journals, LLC
Date: 28-07-2016
Publisher: Penerbit UTM Press
Date: 14-05-2015
DOI: 10.11113/JT.V74.4556
Abstract: Particle-based in-cylinder soot distribution study is becoming more important as the rules and regulations pertaining to particulate emission of diesel-powered vehicles have been increasingly more stringent. This paper focuses on the investigation of soot size evolution and its distribution and transport inside an engine cylinder. The overall process of soot formation includes soot nucleation, surface growth, oxidation, coagulation and agglomeration. The present study considers only soot surface growth, oxidation and coagulation to predict the in-cylinder soot particle size. The soot surface growth model was based on Hiroyasu’s soot formation model while soot oxidation was referred to Nagle & Strickland-Constable’s soot oxidation model. Coagulation rate was defined using Smoluchowski’s equation with constant proposed by Wersborg. From this study, it is demonstrated that soot particles with relatively larger size are gathered in the centre of the cylinder while smaller soot particles are found to be in the region near the wall. Soot number density is considerably high at the start of combustion and reduces sharply afterward while the soot particle size shows the opposite trend. Soot formation rate was found to be dominant at earlier crank angle and is overcome by soot oxidation and coagulation processes that caused lower soot number density but higher soot particle size.
Publisher: Universiti Malaysia Pahang Publishing
Date: 30-12-2017
Publisher: MDPI AG
Date: 14-07-2022
DOI: 10.3390/MA15144888
Abstract: Vibration fatigue characteristics are critical for rotating machinery components such as turbine rotor blades. Lattice structures are gaining popularity in engineering applications due to their unique ability to reduce weight and improve the mechanical properties. This study is an experimental investigation of octet-truss lattice structure utilization in turbine rotor blades for weight reduction and to improve vibration fatigue characteristics. One completely solid and three lattice infilled blades with variable strut thickness were manufactured via additive manufacturing. Both free and forced experimental vibration analyses were performed on the blades to investigate their modal and vibration fatigue characteristics. The blades were subjected to random vibration using a vibration shaker. The response was measured using a triaxial accelerometer in terms of vibration acceleration time histories in the X, Y, and Z directions. Results indicate a weight reduction of up to 24.91% and enhancement in the first natural frequency of up to 5.29% were achieved using lattice infilled blades. The fatigue life of the blades was investigated using three frequency domain approaches, namely, Lalanne, Dirlik and narrow band. The fatigue life results indicate that the 0.25 mm lattice blade exhibits the highest fatigue life, while the solid blade exhibits the lowest fatigue life of all four blades. The fatigue life of the 0.25 mm lattice blade was 1822-, 1802-, and 1819- fold higher compared to that of the solid blade, using the Lalanne, Dirlik, and narrow-band approaches, respectively. These results can serve as the first step towards the utilization of lattice structures in turbine blades, with thermal analysis as the next step. Therefore, apart from being light weight, the octet-truss lattice infilled blades exhibited superior vibration fatigue characteristics to vibration loads, thereby making them a potential replacement for solid blades in turbine rotors.
Publisher: Hindawi Limited
Date: 28-05-2019
DOI: 10.1155/2019/3510245
Abstract: The use of interurban and urban trains has become the preferred choice for millions of daily commuters around the world. Despite the huge public investment for train technology and mayor rail infrastructure (e.g., tunnels), train safety is still a subject of concern. The work described herein reviews the state of the art on research related to critical velocity and backlayering conditions in tunnel fires. The review on backlayering conditions includes the effect of blockages, inclination, and the location of the fire source. The review herein focuses on experimental and theoretical research, although it excludes research studies using numerical modeling. Many studies have used scaled tunnel structures for experimental testing nevertheless, there are various scaling challenges associated with these studies. For ex le, very little work has been done on flame length, fire source location, and the effect of more than one blockage, and how results on scaled experiments represent the behaviour at real-scale. The review sheds light on the current hazards associated with fires in rail tunnels.
Publisher: MDPI AG
Date: 25-01-2021
DOI: 10.3390/EN14030595
Abstract: Impinging jets are considered to be a well-known technique that offers high local heat transfer rates. No correlation could be established in the literature between the significant parameters and the Nusselt number, and investigation of the interactions between the correlated factors has not been conducted before. An experimental analysis based on the twin impingement jet mechanism was achieved to study the heat transfer rate pertaining to the surface plate. In the current paper, four influential parameters were studied: the spacing between nozzles, velocity, concentration of Nano solution coating and nozzle-plate distance, which are considered to be effective parameters for the thermal conductivity and the heat transfer coefficient of TiO2 nanoparticle, an X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis were done, which highlighted the structure and showed that the nanosolution coated the surface homogenously. Moreover, a comparison was done for the experimental results with that of the predicted responses generated by the Design Expert software, Version 7 User’s Guide, USA. A response surface methodology (RSM) was employed to improve a mathematical model by accounting for a D-optimal design. In addition, the analysis of variance (ANOVA) was employed for testing the significance of the models. The maximum Nu of 91.47, where H = S = 1 cm Reynolds number of 17,000, and TiO2 nanoparticle concentration of 0.5% M. The highest improvement rate in Nusselt was about 26%, achieved with TiO2 Nanoparticle, when S = 3 cm, H = 6 cm and TiO2 nanoparticle = 0.5 M. Furthermore, based on the statistical analysis, the expected values were found to be in satisfactory agreement with that of the empirical data, which was conducted by accounting for the proposed models’ excellent predictability. Multivariate approaches are very useful for researchers, as well as for applications in industrial processes, as they lead to increased efficiency and reduced costs, so the presented results of this work could encourage the overall uses of multivariate methods in these fields. Hypotheses: A comparison was done for the predicted responses generated by the Design Expert software with the experimental results and then studied to verify the following hypotheses: ► Preparation of three concentrations of TiO2 nanosolution was done and studied. ► The heat transfer rate could be increased by surface coating with TiO2 nanoparticle. ► The heat transfer could be improved by the impingement jet technique with suitable adjustments.
Publisher: American Society of Mechanical Engineers
Date: 28-07-2019
DOI: 10.1115/AJKFLUIDS2019-5053
Abstract: Swirling flow in pump sump intake has been the subject of discussion for the past decades due to the detrimental effects brought about by its existence. Among the effects of swirling flow are reduced pump efficiency, cavitation, excessive vibration and load imbalance at the pump impeller which are caused by hydraulic problems associated to swirling flow such as swirls and vortices. One of the remedial measures for preventing such occasion is by keeping the pump inlet submerged above a defined value known as the minimum inlet submergence. It is the minimum submergence required to reduce the probability of the occurrence of free surface vortices. However, this requirement may not be fulfilled in some situations due to on site conditions or operational restrictions. In this paper, an experimental study was conducted to investigate the characteristics of swirl angle in the pump intake flow when the pump inlet is submerged near the value of minimum inlet submergence. The ratio of pump submergence to the minimum submergence was varied between 0.8 to 1.2 with constant inlet Froude Number which referred to as submergence ratio. The strength of the swirl in the intake flow was determined by measuring the swirl angle which was accomplished using a swirl meter attached in the suction pipe. Measurements using Acoustic Doppler Velocimeter (ADV) was performed to capture the velocity profile in the intake sump. The swirl angle distribution across the range of submergence ratios was dominated by a subsurface vortex formed at the sump floor. As soon as the submergence was reduced below the minimum submergence, a free surface vortex emerged near the pump inlet and brought a swirl retardation effect to the swirl meter rotation resulting in a bigger fluctuation of the swirl meter reading. An anti vortex device (AVD) called the floor splitter commonly used to reduce vorticity at pump inlet was installed and its effect on the reduction of swirls and vortices was evaluated.
Publisher: Inderscience Publishers
Date: 2017
Publisher: Insight Society
Date: 08-08-2016
Publisher: Springer Science and Business Media LLC
Date: 13-03-2023
DOI: 10.1038/S41598-023-30964-7
Abstract: The growing number of end-of-life vehicles (ELVs) engenders a genuine concern for achieving sustainable development. Properly recycling ELV is paramount to checking pollution, reducing landfills, and conserving natural resources. The present study evaluates the sustainability of India's ELV recycling system from techno-socio-economic and environmental aspects as an instrumental step for assessing performance and progress. This investigation has performed the Strength-Weakness-Opportunity-Threat (SWOT) analysis to evaluate ELV recycling in the long-term viability and examine the critical factors and potential. This research makes practical recommendations for effectively encountering persistent challenges in the ELV recycling system based on Indian values. This research adopts an explorative and Integrated bottom-up mixed approach it interfaces qualitative and quantitative data and secondary research. This study reveals that the social, economic, technological, and environmental aspects of the sustainability of India's ELV recycling system are comparatively limited. The SWOT analysis demonstrates that potential market size and resource recovery are more significant strengths, whereas lack of an appropriate framework and limited technology are major challenges in the recycling of ELVs in India. Sustainable development and economic viability have emerged as great opportunities, while informality and environmental impact have surfaced as primary potential threats to ELV recycling in India. This paper offers insights and yields critical real-world data that may assist in rational decision-making and developing and implementing any subsequent framework.
Publisher: Academic World Research
Date: 07-2020
Publisher: Frontiers Media SA
Date: 04-01-2023
DOI: 10.3389/FBUIL.2022.1038563
Abstract: The issue of end-of-life vehicles (ELV) in Malaysia has recently received serious attention from the government. The Malaysian government has launched various programs to reduce the number of ELVs that have not been adequately managed. Initiatives like offering rewards to those who want to turn up their damaged vehicles are similar to An effort to trade in their old automobiles. However, it was unsuccessful due to a lack of cooperation from Malaysians. This study examines the sociological aspects of community acceptance of ELV legislation in Malaysia. This study assesses community knowledge, attitudes, and readiness to implement ELV management in Malaysia. Six hundred thirty people participated in a cross-sectional survey performed across Malaysian states (Pulau Pinang, Kelantan, Johor, Melaka, Selangor, and Kuala Lumpur). A collection of questions was distributed face-to-face after satisfying the steps of validity and reliability tests. Then descriptive and multiple regression tests were run to determine correlations between variables. We use the structural equation model to determine the model in this research. The study’s findings revealed that people’s knowledge, attitudes, and readiness toward ELV policies were significantly influenced by their length of stay, level of education, and vehicle ownership (overall R2 = 0.663, VIF = 1,612, p = 0.000). It was also discovered that knowledge and attitude together could determine community readiness in implementing ELV policies in Malaysia. The findings of this study demonstrate how important it is for the government to consider the populace’s knowledge and attitudes before implementing the ELV policy in Malaysia.
Publisher: Canadian Center of Science and Education
Date: 24-05-2013
DOI: 10.5539/IES.V6N6P124
Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.663.381
Abstract: Radial Basis Function (RBF) interpolation and trilinear interpolation techniques are compared in the soot particle tracking inside the cylinder of a direct injection engine. The interpolation techniques are used separately in an efficient routine written in Matlab codes which is developed to track the movement or pathline of soot particles in the engine operation cycle ranged from inlet valve closing (IVC) to exhaust valve opening (EVO). Soot particles are treated as a massless body and in spherical shape which will move under the influence of bulk gases flow inside the cylinder. Movement of soot particles are examined through the selection factors of particle's initial coordinate (r,Ɵ,z) and soot concentration level at different instant crack angle. Results obtained from both interpolation techniques are compared and good agreement is achieved with some minor relative difference. However, RBF interpolation has wider applications potential where it can be applied to variety type of mesh geometry as compared to trilinear interpolation which is best used in mesh with hexahedral shape.
Publisher: MDPI AG
Date: 13-04-2018
DOI: 10.3390/EN11040927
Publisher: MDPI AG
Date: 12-10-2022
DOI: 10.3390/SU142013084
Abstract: The circular economy (CE) has been frequently in the news recently, as it offers a regenerative system that substitutes the end-of-life concept with restoration. Despite several benefits yielded by the CE from a triple-bottom-line perspective, India’s end-of-life vehicle (ELV) recycling sector is striving against numerous impediments to implementing the CE approach. Therefore, this paper attempts to shine a spotlight on India’s ELV recycling sector, to identify the potential drivers and barriers to CE implementation. This study has employed an explorative approach to determine the impediments and drivers regarding implementing CE in India’s ELV recycling sector. This research reveals that economic viability (25 percent), environmental degradation (17 percent), and global agenda (15 percent) are the three leading primary drivers. In contrast, limited technology (18 percent), financial constraints (15 percent), and a lack of knowledge and expertise (12 percent) are significant barriers that thwart CE implementation in India’s ELV recycling sector. This paper has made the first attempt to explore the drivers and barriers to implementing CE in the ELV recycling sector in India. Therefore, besides advancing our understanding of opportunities for and threats to implementing CE, this investigation may assist the Indian authorities in devising appropriate policies and strategies and developing a regulatory and legal framework that is conducive to CE and sustainability.
Publisher: MDPI AG
Date: 13-10-2020
Abstract: The inertial sublayer comprises a considerable and critical portion of the turbulent atmospheric boundary layer. The mean windward velocity profile is described comprehensively by the Monin–Obukhov similarity theory, which is equivalent to the logarithmic law of the wall in the wind tunnel boundary layer. Similar logarithmic relations have been recently proposed to correlate turbulent velocity variances with height based on Townsend’s attached-eddy theory. The theory is particularly valid for high Reynolds-number flows, for ex le, atmospheric flow. However, the correlations have not been thoroughly examined, and a well-established model cannot be reached for all turbulent variances similar to the law of the wall of the mean-velocity. Moreover, the effect of atmospheric thermal condition on Townsend’s model has not been determined. In this research, we examined a dataset of free wind flow under a near-neutral range of atmospheric stability conditions. The results of the mean velocity reproduce the law of the wall with a slope of 2.45 and intercept of −13.5. The turbulent velocity variances were fitted by logarithmic profiles consistent with those in the literature. The windward and crosswind velocity variances obtained the average slopes of −1.3 and −1.7, respectively. The slopes and intercepts generally increased away from the neutral state. Meanwhile, the vertical velocity and temperature variances reached the ground-level values of 1.6 and 7.8, respectively, under the neutral condition. The authors expect this article to be a groundwork for a general model on the vertical profiles of turbulent statistics under all atmospheric stability conditions.
Publisher: International Journal of Technology
Date: 30-01-2016
Publisher: Penerbit UTM Press
Date: 07-02-2013
DOI: 10.11113/JT.V60.1432
Abstract: This article presents an assessment for the airborne sound insulation provided by single glazed panels. The glazed panels were glass, acrylic and polycarbonate with a thickness of 4 mm. The experiments were conducted in a transmission loss facility consisting of semi anechoic and reverberation chambers. The panels were subjected to airborne sound and the data collected. Glass, acrylic and polycarbonate panel absorb noise most effectively above 500 Hz with the absorption peaks at 1000 Hz. The single number sound reduction index (RW) for glass, polycarbonate and acrylic were 41 dB, 38 dB and 37 dB, respectively. This could be attributed mainly to the material density which is higher for the glass. Keywords: Sound transmission loss glazing insulation weighted index
Publisher: Elsevier BV
Date: 12-2020
Publisher: Trans Tech Publications, Ltd.
Date: 12-2013
Publisher: Universiti Putra Malaysia
Date: 14-12-2021
Abstract: The COVID-19 pandemic has had dramatic effects on the socio-economic and well beings of Malaysians. The objective of the study is to find the effects of the pandemic on university students both on the technical side, such as the sufficiency of infrastructure and the internet to support online teaching and learning (T& L), as well as on the social side, such as stress level and focus on the study. The nationwide study on the effect of the pandemic on Malaysian varsities students was conducted at the end of 2020. There are many important issues uncovered in this study ranging from the technical side, such as internet-ready programs, socio-economic side, to the psychological perspectives. It shall provide invaluable insights to the related ministries while preparing appropriate reactions during the recovery period. The survey revealed that almost 74% of students highlighted that internet coverage and connectivity was the main issue in online T& L. Although statistics show that 90% of Malaysian households have access to the internet, 49% of students reported that their internet connections were poor. The effects of the pandemic are far-reaching, students belonging to the most vulnerable category find themselves in the most non-conducive place to learn, and they are disturbed by siblings. The socio-economics impacts brought about by the pandemic cause ripple effects onto their families. The government distribution of relief aids has lessened the burden of many people, including students nevertheless, much improvement could be made, especially in the internet facility and coverage.
Publisher: MDPI AG
Date: 14-04-2023
DOI: 10.3390/FIRE6040157
Abstract: In the original publication [...]
Publisher: S. Karger AG
Date: 02-09-2031
DOI: 10.1159/000509283
Abstract: b i Introduction: /i /b Three previous in idual participant data meta-analyses (IPDMAs) reported that, compared to the Structured Clinical Interview for the DSM (SCID), alternative reference standards, primarily the Composite International Diagnostic Interview (CIDI) and the Mini International Neuropsychiatric Interview (MINI), tended to misclassify major depression status, when controlling for depression symptom severity. However, there was an important lack of precision in the results. b i Objective: /i /b To compare the odds of the major depression classification based on the SCID, CIDI, and MINI. b i Methods: /i /b We included and standardized data from 3 IPDMA databases. For each IPDMA, separately, we fitted binomial generalized linear mixed models to compare the adjusted odds ratios (aORs) of major depression classification, controlling for symptom severity and characteristics of participants, and the interaction between interview and symptom severity. Next, we synthesized results using a DerSimonian-Laird random-effects meta-analysis. b i Results: /i /b In total, 69,405 participants (7,574 [11%] with major depression) from 212 studies were included. Controlling for symptom severity and participant characteristics, the MINI (74 studies 25,749 participants) classified major depression more often than the SCID (108 studies 21,953 participants aOR 1.46 95% confidence interval [CI] 1.11–1.92]). Classification odds for the CIDI (30 studies 21,703 participants) and the SCID did not differ overall (aOR 1.19 95% CI 0.79–1.75) however, as screening scores increased, the aOR increased less for the CIDI than the SCID (interaction aOR 0.64 95% CI 0.52–0.80). b i Conclusions: /i /b Compared to the SCID, the MINI classified major depression more often. The odds of the depression classification with the CIDI increased less as symptom levels increased. Interpretation of research that uses diagnostic interviews to classify depression should consider the interview characteristics.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Penerbit Universiti Kebangsaan Malaysia (UKM Press)
Date: 15-06-2018
Publisher: Cambridge University Press (CUP)
Date: 09-01-2013
DOI: 10.1017/JFM.2012.531
Abstract: Research into high-Reynolds-number turbulent boundary layers in recent years has brought about a renewed interest in the larger-scale structures. It is now known that these structures emerge more prominently in the outer region not only due to increased Reynolds number (Metzger & Klewicki, Phys. Fluids , vol. 13(3), 2001, pp. 692–701 Hutchins & Marusic, J. Fluid Mech. , vol. 579, 2007, pp. 1–28), but also when a boundary layer is exposed to an adverse pressure gradient (Bradshaw, J. Fluid Mech. , vol. 29, 1967, pp. 625–645 Lee & Sung, J. Fluid Mech. , vol. 639, 2009, pp. 101–131). The latter case has not received as much attention in the literature. As such, this work investigates the modification of the large-scale features of boundary layers subjected to zero, adverse and favourable pressure gradients. It is first shown that the mean velocities, turbulence intensities and turbulence production are significantly different in the outer region across the three cases. Spectral and scale decomposition analyses confirm that the large scales are more energized throughout the entire adverse pressure gradient boundary layer, especially in the outer region. Although more energetic, there is a similar spectral distribution of energy in the wake region, implying the geometrical structure of the outer layer remains universal in all cases. Comparisons are also made of the litude modulation of small scales by the large-scale motions for the three pressure gradient cases. The wall-normal location of the zero-crossing of small-scale litude modulation is found to increase with increasing pressure gradient, yet this location continues to coincide with the large-scale energetic peak wall-normal location (as has been observed in zero pressure gradient boundary layers). The litude modulation effect is found to increase as pressure gradient is increased from favourable to adverse.
Publisher: Elsevier BV
Date: 12-2013
Publisher: IEEE
Date: 12-2016
Publisher: MDPI AG
Date: 21-11-2022
DOI: 10.3390/SU142215441
Abstract: Over the last couple of decades, the automobile sector in India has seen dramatic growth, following the phenomenal booming of engenders rapid proliferation of end-of-life vehicles (ELVs). Therefore, efficient and sustainable handling of ELVs is paramount. India has been striving to establish a practical regulatory framework to handle ELVs sustainably. This study explores India’s current ELV recycling system to promote sustainable development. Subsequently, this article evaluates the present ELV recycling system to determine the existing issues in ELV recycling to prevent failure and enhance and standardize the processes involved in ELV recycling to achieve the optimum standard for product and process quality. This paper proposes pragmatic frameworks and offers recommendations for setting up an efficient ELV recycling system to resolve current issues and expedite sustainable development. This study has been performed through a mixed-method approach a literature and policy review accompanied by detailed structured interviews with major stakeholders and industrial visits. This investigation reveals that India’s ELV recycling system is at the embryonic stage and struggling against numerous inherent impediments. However, the proposed frameworks, together with practical recommendations, provide a paradigm for expediting materials recycling from ELVs and resolving perennial issues. This research may assist the government of India in implementing any upcoming regulatory and legal framework.
Publisher: Elsevier BV
Date: 11-2013
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
Publisher: IOP Publishing
Date: 10-2016
Publisher: IOP Publishing
Date: 10-2016
Publisher: Elsevier BV
Date: 09-2023
Publisher: Trans Tech Publications, Ltd.
Date: 11-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.225.109
Abstract: Single normal hot-wire measurements of the streamwise component of velocity were taken in boundary layer flows subjected to pressure gradients at matched friction Reynolds numbers Reτ ≈ 3000. To evaluate spatial resolution effects, the sensor lengths are varied in both adverse pressure gradient (APG) and favorable pressure gradient (FPG). A control boundary layer flow in zero pressure gradient ZPG is also presented. It is shown here that, when the sensor length is maintained a constant value, in a contant Reynolds number, the near-wall peak increases with (adverse) pressure gradient. Both increased contributions of the small- and especially large-scale features are attributed to the increased broadband turbulence intensities. The two-mode increase, one centreing in the near-wall region and the other one in the outer region, makes spatial resolution studies in boundary layer flow more complicated. The increased large-scale features in the near-wall region of an APG flow is similar to large-scales increase due to Reynolds number in ZPG flow. Additionally, there is also an increase of the small-scales in the near-wall region when the boundary layer is exposed to adverse pressure gradient (while the Reynolds number is constant). In order to collapse the near-wall peaks for APG, ZPG and FPG flows, the APG flow has to use the longest sensor and conversely, the FPG has to use the shortest sensor. This study recommends that the empirical prediction by Huthins et. al. (2009) to be reevaluated if pressure gradient flows were to be considered such that the magnitude of the near-wall peak is also a function of the adverse pressure gradient parameter.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Begellhouse
Date: 2018
DOI: 10.1615/THMT-18.940
Publisher: IOP Publishing
Date: 11-04-2017
Publisher: Springer Science and Business Media LLC
Date: 11-11-2017
Publisher: MDPI AG
Date: 02-10-2022
DOI: 10.3390/SU141912573
Abstract: Various uncertainties exist in the End-of-Life Vehicle (ELV) industry, which further complicates the ELV business’s growth. In order to pursue greater progress in the ELV business establishment, a comprehensive analysis of previous ELV studies with regard to the supply chain uncertainty perspective is essential. The objective of this study is aimed at categorising the existing supply chain uncertainty sources according to their end-of-life (EoL) strategies, identify the management approaches adopted to analyse the prominent research trends, and conduct a regional analysis of ELV supply chain studies for the past years, from 2016 until 2022. The content analysis method was used to extract all the essential information from previous research, and an analysis was performed to obtain the latest research trends and identify the relationship between the gathered data. The findings show that the past research focuses on three main supply chain uncertainties, namely, uncertainty in logistics and network facilities (31.8%), production and operations (30.7%), and environmental (25.0%). Furthermore, the regional analysis shows that 83% of the studies were conducted in developing countries over the past years. Lastly, several research gaps were presented to provide researchers with potential directions and the way forward to explore ELV supply chain research from the uncertainty management context.
Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.629.450
Abstract: This study concerns with aerodynamic drag on a passenger car. By using computational fluid dynamics (CFD) method, we found that values of skin friction coefficients for three different parts of the car: front, top and rear parts, are different. This study addresses three different basic possible flows around a car: favourable, zero and adverse pressure gradients. Generally, cars use approximately 20% of their engine power to overcome aerodynamic drag, which is generally proportional to the frontal area. The boundary layer at each position has been analyzed to ascertain the effect of wall shear stress on the car surface. It is found that the value of wall shear stress velocity is highest at the rear part, followed by front and top parts. Subsequently, it is shown that the front part has the thinnest viscous region despite not being the part with the highest local ambient velocity compared with the top and rear parts. Despite its supposed aerodynamic shape, the rear part of the car sees separation of flow and the total drag per unit area here is the largest, twice as large as front part and more than seven times larger than the top part.
Publisher: Springer Science and Business Media LLC
Date: 10-01-2015
Publisher: MDPI AG
Date: 17-08-2022
DOI: 10.3390/SU141610201
Abstract: The growth of Indonesia’s automotive sector has increased the number of end-of-life vehicles (ELVs), making ELV waste management a major issue. Most countries, such as Japan, China, and Europe, manage ELV waste well, but developing countries still do not. In developing countries, little is known about ELV social admissions. This study analyzes ELV management social acceptance in developing countries. Three hundred nine respondents from Jakarta, Bogor, Depok, Tangerang, and Bekasi (the district in Indonesia) were surveyed in a cross-sectional. A set of questions was designed to determine social acceptance (attitude, knowledge, social influence, institutional trust, health issues, and acceptance). After passing validity and reliability tests, the hypothesized research model was estimated using structural equitation. According to this study, social influence, attitude, knowledge, institutional trust, and health issues influenced public acceptance. The health issues variable was also a good moderator (Adj. R2 = 0.173, p 0.001, average path coefficient = 0.299). The analysis of social acceptance models related to ELV management found that social influence, attitude, knowledge, and institutional trust play a role in one’s desire to accept a new rule, and health issues can strengthen a person in the admission process.
Publisher: Begellhouse
Date: 2012
DOI: 10.1615/ICHMT.2012.PROCSEVINTSYMPTURBHEATTRANSFPAL.2170
Publisher: Penerbit Universiti Kebangsaan Malaysia (UKM Press)
Date: 30-05-2020
DOI: 10.17576/JKUKM-2020-32(2)-09
Abstract: Many tunnels have been built to reduce traffic volumes in densely populated urban areas. In this research, a series of small-scale experiments were carried out in a 3 m length model tunnel with 0.6 m width and 0.95 m height to examine the temperature distribution along the tunnel ceiling. The containers for the source of the fire in this study were six different sizes of pools filled with n-heptane and gasoline. The smoke maximum temperature has been investigated experimentally and theoretically beneath the tunnel ceiling. A few results are obtained, firstly, dimensional analysis proposed in this research resulted in a theoretical estimation model for predicting maximum gas temperature under the ceiling. Then, the results from theoretical equation were compared with experimental data and an acceptable prediction was presented. The temperature distribution and smoke emission relationship with various ventilation velocities and heat release rate (HRR) were analyzed. The results show that an increase in ventilation velocity leads to temperature decrease and the fire source with higher HRR causes higher maximum smoke temperature. Furthermore, since the maximum temperature and the gas temperature decrease beneath the ceiling of the tunnel during the fire affect the tunnel structure, these parameters were also considered. Experimental results were also compared with that of Kurioka’s model. Empirical correlations for flow temperature decay along the tunnel were also proposed based on experimental data.
Publisher: IEEE
Date: 12-2016
Publisher: Qeios
Date: 09-01-2022
DOI: 10.32388/O3P7ZK
Publisher: Informa UK Limited
Date: 27-07-2021
Publisher: IOP Publishing
Date: 2017
Publisher: MDPI AG
Date: 11-12-2021
DOI: 10.3390/SYM13122392
Abstract: The purpose of this numerical research is to assess the evacuation process in a tunnel under the contraflow condition. Numerical simulations utilizing FDS+Evac codes associated with a fire dynamic simulator (FDS) model simulating a fire scenario are used to simulate evacuation and to predict the impact of a 100 MW fire scenario on the occupants inside the tunnel. Traffic and passenger conditions are based on real data from a tunnel in the UK. Two fire loads, 100 MW and 5 MW, are studied to represent an HGV and a passenger car fire. The 100 MW fire source, caused by an unexpected heavy good vehicle (HGV) catching fire, is located in the middle of the tunnel and at 20% of tunnel length to study the effect of fire source location on the usage of emergency exits and tenability thresholds. The dimensions and the inclination angle of the existing roadway tunnel are 1836 m (L) × 7.3 m (W) × 5 m (H) and 4%, respectively. It should be noted that the 4% inclination of the tunnel causes asymmetry propagation of smokes thus the visibility of the downstream and upstream from the fire behave differently. The maximum needed time to evacuate using all egress, the amount of fractional effective dose and visibility at the human’s height are analyzed. Simulation results indicate that when a realistic worst-case fire scenario is modeled, all evacuees can survive before the combustion gases and heat influence their survivability.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Penerbit Universiti Kebangsaan Malaysia (UKM Press)
Date: 30-05-2021
DOI: 10.17576/JKUKM-2021-33(2)-08
Abstract: 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.
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 12-2020
Publisher: MDPI AG
Date: 07-03-2019
DOI: 10.3390/MI10030176
Abstract: Here, the researchers carried out an experimental analysis of the effect of the TiO2 nanosolution concentration on the heat transfer of the twin jet impingement on an aluminum plate surface. We used three different heat transfer enhancement processes. We considered the TiO2 nanosolution coat, aluminum plate heat sink, and a twin jet impingement system. We also analyzed several other parameters like the nozzle spacing, nanosolution concentration, and the nozzle-to-plate distance and noted if these parameters could increase the heat transfer rate of the twin jet impingement system on a hot aluminum surface. The researchers prepared different nanosolutions, which consisted of varying concentrations, and coated them on the metal surface. Thereafter, we carried out an X-ray diffraction (XRD) and a Field Emission Scanning Electron Microscopy (FESEM) analysis for determining the structure and the homogeneous surface coating of the nanosolutions. This article also studied the different positions of the twin jets for determining the maximal Nusselt number (Nu). The researchers analyzed all the results and noted that the flow structure of the twin impingement jets at the interference zone was the major issue affecting the increase in the heat transfer rate. The combined influence of the spacing and nanoparticle concentration affected the flow structure, and therefore the heat transfer properties, wherein the Reynolds number (1% by volume concentration) maximally affected the Nusselt number. This improved the performance of various industrial and engineering applications. Hypothesis: Nusselt number was affected by the ratio of the nanoparticle size to the surface roughness. Heat transfer characteristics could be improved if the researchers selected an appropriate impingement system and selected the optimal levels of other factors. The surface coating with the TiO2 nanosolution also positively affected the heat transfer rate.
Publisher: MDPI AG
Date: 10-02-2023
DOI: 10.3390/FIRE6020065
Abstract: Some of the most critical transportation infrastructures are road tunnels. Underground passageways for motorists are provided through this cost-effective engineering solution, which allows for high traffic volumes. A crucial aspect of the operation of road tunnels is fire safety. Risk assessments have been established to ensure the level of safety in tunnels. As the existing quantitative risk analysis (QRA) models are inapplicable to assess the fire risk in UK road tunnels, this paper presents a novel QRA model, named LBAQRAMo, for UK road tunnels. This model consists of two main sections: quantitative frequency analysis, to estimate the frequency of fire incidents via an event tree and quantitative consequences analysis, to model the consequences of fire incidents. LBAQRAMo covers the risk to tunnel users. The result of the risk analysis is the expected value of the societal risk of the investigated tunnel, presented via F/N curve. Another major result of this model is the estimation of the number of fatalities for each scenario based on the comparison between required safe egress time (RSET) and available safe egress time (ASET). Risk evaluation was carried out by comparison of the tunnel under study with the UK ALARP limit. The operation of the model is demonstrated by its application to the Gibraltar Airport Tunnel as a case study. Simulation of 34 different possible scenarios show that the tunnel is safe for use. The sensitivity of the model to HGV fire incident frequency and basic pre-movement times was studied as well.
Publisher: Penerbit UTM Press
Date: 23-06-2016
DOI: 10.11113/JT.V78.9189
Abstract: This manuscript contains the development stages of a multi-purpose wind tunnel built at the Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The fully automated wind tunnel is named Pangkor after an island in Perak, Malaysia. The development of the wind tunnel consists of three stages namely the design, fabrication and testing & commissioning. The computational fluids dynamic (CFD) approach was employed to ascertain the main geometries to optimize space utilization. Calculations are made based on typical wind tunnel design guidelines. Pitot tubes-pressure transducer, hotwire anemometry, temperature, room humidity and barometric sensors were used to verify actual flow of our construction. A traverse installed at the wind tunnel is capable of a two dimensional movements. The 15 kW axial fan used is especially selected because of space limitation. A variable frequency drive (VFD) connected to fan’s motor allows velocity control from a computer. All devices are connected a computer with one single controlling software Scilab – ensuring ease of operation. The project shows that, with a limited budget, a wind tunnel with full functionalities could be constructed
Publisher: Penerbit Universiti Kebangsaan Malaysia (UKM Press)
Date: 09-2018
Publisher: MDPI AG
Date: 18-07-2016
DOI: 10.20944/PREPRINTS201607.0050.V1
Abstract: In this paper, the boiling flow inside a nanochannel with 700000 argon particle has been simulated by molecular dynamics (MD) simulation. This approach has been employed to analysis the superheated flow and its heat transfer pattern as well. For all simulations an external thrust force varying from 1 PN to 12 PN is exerted on inlet nanoparticles along the channel to have the forced annular boiling flow. Computations reveal that saturation condition and superheat degree have significant impacts on the liquid-vapor interface. Furthermore, because of the major influence of surface tension throughout a nanochannel, the x-velocity of liquid film and vapor core has not considerable fluctuations and stay smooth. All provided results show the behaviors completely similar to the available outcomes in the literature.
Publisher: SAE International
Date: 14-04-2015
DOI: 10.4271/2015-01-1075
Publisher: Springer Science and Business Media LLC
Date: 13-06-2019
Publisher: Universiti Malaysia Pahang Publishing
Date: 30-12-2016
Publisher: Trans Tech Publications, Ltd.
Date: 10-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.663.366
Abstract: The design of the ventilation and fire safety systems for the Johor Bahru Sentral, a semi-underground train station, part of the Integrated Custom, Immigration and Quarantine Complex (ICIQ) is based on normal Malaysian Standards (MS), British Standards and the local fire department’s requirements. However, the large and complex space in the underground station coupled with scheduled diesel-powered locomotives which frequent the station by stopping or passing require detailed simulations. Both ventilation and the fire safety systems employ Computational Fluid Dynamic (CFD) methods to provide realistic balance against the typical calculations based on spread sheets and certain design software. This study compares smoke simulations results performed by the mechanical and fire consultants with the simulations carried out through this project. An assumption of a locomotive catches fire near the main platform is made. The burning locomotive is the source of the smoke while the occupants on platforms and waiting areas are the subjects to escape safely. The process of the simulation includes modelling and meshing processes on the structure of the railway station imported from Inventor CAD Autodesk software drawing. The CFD simulations are performed using Star-CCM+. The smokes flow around the building with buoyancy forces and extracted via exhaust fans. Through these simulations, we found that when a locomotive catches fire, the passengers could evacuate the building safely before the fire department machinery arrives. Furthermore, we notice that the ventilation fans activation based on detection of hazardous gases may not be efficient way to remove the latter. A schedule clean-up sync with train arrivals effectively removes toxic gas.
Publisher: Springer Science and Business Media LLC
Date: 16-03-2018
Publisher: Universiti Malaysia Pahang Publishing
Date: 30-06-2017
Publisher: MDPI AG
Date: 10-08-2023
DOI: 10.3390/SU151612244
Abstract: The usance of electric and electronic products has become commonplace across the globe. The growing number of customers and the demand for these products are resulting in the manufacturing of new electrical and electronic products into the market, which is ultimately generating a plethora of e-waste. The notion of a circular economy (CE) is attracting more researchers to work in the growing field of e-waste management. Considering e-waste as a prominent menace, the objective of this study was to undertake a comprehensive review of the literature by analyzing the research articles published in the MDPI Sustainability journal pertaining to the topic of e-waste in the context of operations and supply chain management (OSCM). This study was addressed via three research questions. A total of 87 selected papers from 2014 to 2023 were analyzed, reviewed, and categorized after data were collected from Web of Science (WOS) and Scopus academic databases with articles only published in the MDPI Sustainability journal. This entails identifying prominent research themes, publication trends, research evolution, research clusters, and industries related to e-waste through descriptive analysis. The field of study and methods employed were analyzed by means of content analysis by delving into the main body of the published articles. Further, four major research themes and clusters were identified: (1) closed-loop supply chains (2) e-waste (3) sustainable development and (4) waste electrical and electronic equipment (WEEE). Consequently, this review can be a foundation for subsequent scholarly pursuits toward e-waste management and fresh lines of inquiry for the journal. Finally, in the conclusion section, some future research guidelines are also provided.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Hindawi Limited
Date: 04-03-2023
DOI: 10.1155/2023/3666224
Abstract: Background. There is an agreement on the importance of measuring work-life balance, especially after the COVID-19 pandemic. However, the available tools to do so are not sufficient to address all dimensions, contexts, and professions. Aim. The article reviews existing instruments that have been widely utilised to tap into the breadth and depth of work-life balance. Evaluation. This is a perspective scoping review guided by PRISMA-ScR guidelines. Articles reporting on the measurement of work-life balance were reviewed. The authors performed the review based on agreed-upon search terms, inclusion and exclusion criteria, search databases, and the data extraction process. Key Issues. The existing tools appear to have ergent underpinning theoretical models, factors, structural sychometric properties, and the number of accumulated citations. The existing tools also varied in terms of their target sector, with limited tools available for the analysis of work-life balance among healthcare professionals. We argue that while the existing tools provide a general base for the work-life balance measurement, it would be imperative to adjust those tools to the specific cultural and professional contexts. Future work-life balance measures should consider the changes imposed by atypical or disruptive events that have the potential to alter work-life balance, such as in the case of the COVID-19 pandemic. The onus is on researchers and policymakers to work collaboratively in each context to adapt, implement, and evaluate those tools as they become integrated into the matrix of labour market assessments in the future. Conclusions. The article highlighted current gaps and improvement opportunities in the work-life balance measurement field. Implications for Healthcare and Nursing Management. The maintenance of work-life balance will remain an issue for years to come. Ensuring comprehensive and context-specific measurements would be essential to guide the evidence-based recommendations necessary to support the workforce across the various sectors of the economy in the future.
Publisher: e-IPH Ltd.
Date: 28-12-2020
DOI: 10.21834/EBPJ.V5ISI3.2578
Abstract: In this article, the focus is on understanding the awareness of sustainable design & product and health & safety among engineering and architectural students at university levels as these young graduates are representative of the workforce. This survey was conducted at five public universities in Peninsular Malaysia. On average, the majority of respondents provided positive responses (more than 80%) on the needs of sustainable design & product and health & safety aspects in their workplaces. These figures bode well for such an ambitious country to be on par with developed countries. It is also noteworthy to highlight that a significant portion who are not comfortable with investing with sustainable features. Keywords: Sustainable Design & Products Health and Safety (H& S) eISSN: 2398-4287© 2020. The Authors. Published for AMER ABRA cE-Bsby e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (icenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. DOI: 0.21834/ebpj.v5iSI3.2578
Publisher: IEEE
Date: 11-2017
Publisher: IOP Publishing
Date: 03-2018
Publisher: Universiti Malaysia Pahang Publishing
Date: 30-03-2017
Publisher: Penerbit Universiti Kebangsaan Malaysia (UKM Press)
Date: 30-04-2019
DOI: 10.17576/JKUKM-2019-31(1)-17
Abstract: The article focuses on the numerical investigation of temperature distribution in a central processing units (CPU) case with different time interval such as t = 100 s, 200 s, 300 s, 400 s, 500 s. Heat sink performance of a graphics processing unit (GPU) thermal management and impacts of different shape and velocity on the thermal performance are considered. In this study, three heat sink models are designed (A, B, and C) based on the volume area of heat sink. This study emphasizes the heat transfer phenomena caused by a GPU in a computer case in both steady state and transient state. A CFD software STAR – CCM + is used to carry out to study the fluid flow and heat transfer simulation of graphics card heat sink in a computer case and the same time an enhanced method of reducing the temperature of GPU is proposed. The results show that heat sink B with the least volume area, has the fastest rate of heat exchange followed by heat sink C and heat sink A. Likewise, the result indicates an inverse relationship between the volume and the total surface of the heat sink and the final temperature of the graphics card chip. As the total volume and surface of the heat sink increases, the rate of heat transfer increases via faster rate of conduction between graphics card chip to heat sink meanwhile the cooling of the heat sink is aided by wind inlet via convection.
No related grants have been discovered for Zambri Harun.