Physics, Engineering and Material Science

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A decision support system for demolition safety risk assessment
(Universiti Teknologi Malaysia, 2016) Mohammadi, Farahbod
Demolition can be defined as dismantling, razing, destroying or wrecking of any building or structure or any part thereof. Demolition work involves many of the hazards associated with construction. However, demolition also involves additional hazards due to unknown factors which makes demolition work particularly dangerous. In order to make the demolition project safer, everyone at a demolition site must be fully aware of the hazards they may encounter and the safety precautions that they must take to protect themselves and their employees. Safety risk assessment is a planning tool that can be used to improve safety performance at demolition site. In the absence of a special tool for demolition safety risk assessment, a prototype Decision Support System (DSS) based on failure mode and effect analysis that enables decision makers to systematically and semi-quantitatively identify, analyze and evaluate safety risks factors in demolition project has been developed. The prototype is named Hybrid Demolition Safety Risk Assessor (HDSRA). It has three modules; (i) safety risk identification, (ii) safety risk analysis and (iii) safety risk evaluation. Module one aids the decision makers to identify thirty-seven safety risks that is developed by reviewing safety literatures and forming consensus among Delphi panel of experts. In addition, the module introduces seven immediate causes that trigger occurrence of those thirty-seven safety risks. The second module comprised a hybrid decision making model based on Decision Making Trial and Evaluation Laboratory (DEMATEL) and Analytic Network Process (ANP) that relatively estimates likelihood of thirty-seven safety risks with respect to seven immediate causes. The third module evaluates and prioritizes the safety risks by using two ranking methods; Analytic Hierarchy Process (AHP) and VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR). The HDSRA prototype is then developed by integrating module 1, 2 and 3 and evaluated by a group of demolition experts. HDSRA acts as information source that can be used by demolition contractors to identify safety risks in a systematic way. Therefore, possibility of raising error during risk identification process in the implementation of demolition work is reduced. Decision support system that is produced by the HDSRA prototype, proactively proposes action that should be taken by demolition safety experts to control risks at workplace. And finally, HDSRA can be also used as a training tool to raise safety awareness among demolition workers.
A decision support system for sustainable development of biodiesel industry
(Universiti Teknologi Malaysia, 2016) Mohammadi Ashnani, Mohammad Hossein
Energy plays a crucial role in modern life. The recent crises in the world oil market, rapid depletion of crude oil reserves along with growing concerns about emission of greenhouse gas have drawn attention to biofuels sources. Despite the many positive characteristics of biofuels, they cause a variety of environmental, economical, and social challenges that are not known to decision-makers by conventional evaluation tools such as Environmental Impact Assessment. This study designed and developed a specific Decision Support System (DSS) to analyze the sustainability of alternative biodiesel production in Malaysia by integrating and using Eco-indicator 99 method as a damage oriented Life Cycle Assessment (LCA), spatial analysis and Analytic Hierarchy Process (AHP). DSS was carried out to estimate four sustainability damage categories covering human health, ecosystem quality, resources depletion and socio-economic aspects to help decision makers in achieving a holistic insight into the entire system. LCA results show that fossil fuels depletion impact is the highest contributor to the environmental burdens of palm oil and jatropha biodiesel production, by 1.5E3 MJ and 1.99E3 MJ surplus respectively. This is followed by the respiratory inorganics impact with 1.32 E-3 and 3.28 E-4 Disability-Adjusted Life Year (DALY) for palm oil and jatropha biodiesel productions respectively. LCA as environmental analysis tool and Geographical Information System as spatial analysis tool were combined to provide an integrated methodology that is able to determine land use change impacts. Land use change analysis showed that approximately 42.2% of expansion during the period was the result of the conversion of forest, followed by agroforest and plantations (34.8%). The study used AHP to assign criteria weights from a Malaysian perspective. According to AHP analysis, the importance weights of both human health (40.9%) and ecosystem quality (32.2%) damages are higher than both resources depletion (16.5%) and socio-economic (10.4%) damages. Combining the effects on all impact categories as a single score supports the notion that the palm oil biodiesel production with 30.5 Eco-indicator point (Pt) generates 9.7% higher negative impacts on sustainability than jatropha biodiesel production which means jatropha development is more consistent with sustainability criteria and furthermore it could be beneficial in Clean Development Mechanism projects
A gate-to-gate sustainability assessment method for the Malaysian food manufacturing industry
(Universiti Teknologi Malaysia, 2019) Ahmad, Shamraiz
Activities of today's manufacturing industries have significant impact on all three dimensions of sustainability (environment, economy and society). Although, methods or frameworks have been developed for sustainability assessment, only limited numbers consider all the three dimensions of sustainability. There is rarely a method that considers both stochastic and fuzzy uncertainties simultaneously. Moreover, there is no such method that is based on a weighted and comprehensive set of sustainability indicators for the Malaysian food manufacturing industry. Although food manufacturing is a key industry in Malaysia from the economy and food security viewpoints, it lags behind in applying sustainability practices in its operations. Thus, the development of a comprehensive and integrated stochastic-fuzzy sustainability assessment method for the Malaysian food manufacturing industry is the main objective of this research. This method employed 57 weighted sustainability indicators for all three dimensions of sustainability (triple-bottom line concept of sustainability). The Delphi method was used for the development of these indicators and their weights. The new integrated method included both quantitative and qualitative indicators to perform a systematic gate-to-gate sustainability assessment. This has made it more useful for internal decision making at industry and plant levels. Monte Carlo simulation and fuzzy logic were used to address stochastic and fuzzy uncertainties respectively in an integrated way. Based on stochastic and fuzzy modeling, an overall unit-less sustainability index was generated to evaluate the performance level of sustainability. The Crystal Ball software for Monte Carlo simulation and Fuzzy Logic toolbox of Matlab for fuzzy logic evaluation were used. The applicability of the developed method was demonstrated using two case studies in the Malaysian food manufacturing industry. The analysis showed that the first case company has an "average" sustainability performance with a sustainability index of 0.42. The second company with a sustainability index of 0.43 also falled into the "average" performance range. The case studies and validation process showed that the developed method was useful for evaluating sustainability performance within a system containing complicated uncertainties. Overall, this research has contributed in expanding the knowledge on the sustainable manufacturing and sustainability assessment, and provided practical guidelines for practitioners to evaluate, predict, and improve the sustainability performance of their companies using the developed assessment method.
A hybrid model for assessing the quality performance of demolition contractors
(Universiti Teknologi Malaysia, 2015) Mohammadali Kazerooni
The demolition project is reasonably labour-intensive and the shortage of qualified demolition contractors resulted in poor workmanship in many demolition projects. The current performance assessment of demolition contractors in Malaysia is highly based on subjective evaluation while a few of authorities and clients incorporated contractor past performance within the quality assessment process. This is due to the lack of an assessment framework that can supports the evaluation process of demolition contractors. However, different contractor’s quality assessment methods have been successfully developed, but, there has been limited effort to view complexity parameters in the process of evaluation. Hence, it made it necessary to identify an appropriate assessment criteria in order to evaluate the quality of demolition contractor’s performance in a structured way along with considering the complexity of demolition project. This research first applied the Delphi method as a scientific means to collect the required information for developing of the assessment framework, which constitutes thirty performance indicators for demolition contractors. Then, an assessment method has been developed in the form of a hybrid Quality Function Deployment (QFD) and Cybernetic Analytic Network Process (CANP) model for demolition contractors. This involves the use of QFD to translate the customer’s expectations into assessment indicators and the CANP to weight the expectations and assessment criteria. Three different case studies were used to demonstrate the implementation of the model and the results indicated that despite the extensive consideration on cost and time in the assessment of demolition contractors, the safety indicators were rated as the most significant Malaysian clients’ expectations for quality assessment of demolition contractor. The results also show that, the project complexity indicators, comparatively received high priority in the quality assessment of demolition contractors among all other indicators. In conclusion, this research has demonstrated that the developed hybrid model is an effective tool for assessing the quality of demolition contractor’s performance and it is hoped that the research work may provide a first step into a better customer-driven demolition project, and eventually increase the quality of demolition projects over time
A model of retrofit energy efficiency for sustainable building by using energy performance contract method in Malaysia
(Universiti Teknologi Malaysia, 2019) Kiani, Iman
Recently, attempts have been made to improve the efficiency of energy use in buildings in many countries all over the world. Most hotel buildings are deemed as unprofitable non-energy efficient constructions whilst renovations to their energy-efficient system are still non-resolute or unexplored. The Retrofit Energy Efficiency Sustainable Hotel Building (REESH) is not only the best opportunity to minimize energy use, but it also enhances environmental protection, cost-efficient use of resources and health benefits for residents. Sustainable development strategies need a variety of modification towards the sustainability of existing buildings. Improvements can be made based on the concept of Integration Sustainable Development (ISD) on existing buildings by retrofit. The REESH projects are in compliance with the sustainable model development strategy and can be done through the Energy Performance Contract (EPC) method which uses performance indicators to measure the efficiency of the REESH project. This study adapts the energy efficiency strategies to produce energy efficient hotel buildings through the energy contracting method. It also produces energy efficiency modifications to be sustainable in Malaysia. The main objective of the study is to identify the Key Performance Indicators (KPIs) and Critical Success Factors (CSF) for hotel building renovations using the EPC methods. The second objective is the development of the REESH model that relates to REESH‘s CSF and KPI using the Decision-Making Trial and Evaluation Laboratory Process (DEMATEL), hybrid method and model comparison. The third objective is to find out the barriers to the implementation of the guidelines. The last objective entails the evaluation of the Guideline Retrofit Energy Efficiency for Hotel (GREESH) by taking into consideration the REESH‘s model which is required to specify its benefits and limitations. The academic experts and private parties reviewed the validity of GREESH and Model evaluations. The main outcome of this study is the establishment of the REESH model and GREESH guideline that links the 53 CSFs, 8 KPIs and sustainable dimensions for REESH building in Malaysia. From this study it is observed that the most important factors in REESH are project objectives control method, contract type, access to technology, contract award method, effective coordination, organizational leadership capability, accurate measurement and verification, mutual trust, rational organizational structure, time management, and technical background staff related to REESH building in Malaysia. The concluding remark of the research is a proposed model for establishing a retrofit guideline towards the RESSH buildings in Malaysia by using the EPC method.
A model structure of sustainability aspects for green commercial office property valuation
(Universiti Teknologi Malaysia, 2016) Jasimin, Tuti Haryati
Sustainability principle consists of environmental, social and economic aspects were recognized globally as among the factors that are affecting the green commercial office property and potentially its value of which valuers should be aware of. However, there is a lack of consideration to the potential impacts of the underlying sustainability principle to the market value of green commercial office property in Malaysia. There is a lack of data into sales and lease transactions for green commercial office buildings that exhibit green features. In Malaysia, there is also a lack of research yet to be conducted and be practiced that look into sustainability aspects. The main objective of this study is to develop a structural model of sustainability aspects for the purpose of property valuation from a Malaysian context. The research methods involved the clarification of the problems, objectives, theoretical, and empirical research through quantitative means by conducting survey to the occupants of green commercial office buildings. The results from the quantitative study were then validated by real estate experts through a focus group discussion (FGD). This study employed Structural Equation Modelling (SEM) analysis using the Analysis of Moments Structures (AMOS) software in the quantitative study and ATLAS.ti software in analyzing the qualitative data. The proposed structural model was beneficial to the valuation industry. It provides valuable information on factors and attributes of green commercial office property that are impacting the value, which the valuer should consider in the valuation process. The findings suggest that the most significant identified factors to be taken into valuation consideration for each aspect were locational, occupants' satisfaction and well-being, and also rental growth. All factors and attributes that are exhibited in the model were identified as significantly correlated to each other
A modified savonius turbine with moveable blades for higher efficiency
(Universiti Teknologi Malaysia, 2015) Abbasabadi, Reza Hassanzadeh
Previous research works have proposed Savonius vertical axis marine current turbine as appropriate for low current velocity applications such as in the Malaysian sea. The numerous benefits of Savonius turbine such as its simple structure, self-start ability, relatively low operating velocity, independence from flow direction and low environmental impact have generated interests among researchers. Despite these advantages, it suffers from low efficiency. Savonius turbine is composed of multiple physical parts; in which in this study, certain important parameters including blades, end plate, aspect ratio and overlap ratio had been investigated. This thesis proposes a newly modified Savonius turbine, designated ReT (Reza Turbine), for low speed marine currents to enhance the efficiency. The ReT consists of two blades, each blade divided into two parts which are joined by hinge. This makes ReT considerable as a turbine with movable blades. The blades, being movable, necessitates a specific design of endplates to ensure the blades to function properly. This research explored the nonlinear two-dimensional flow numerically over the novel type rotor. Simulations were conducted using Computational Fluid Dynamics (CFD) software, by applying the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The unsteady Reynolds Averaged Navier-Stokes (RANS) equations were solved for velocity and pressure coupling with a code, based on the programming Language C through the User Defined Functions (UDF) at variation of marine current velocities. Dynamic Mesh Method (DMM) was used for solving the movement of the blades and adjusting the mesh according to the position of the blades on the surface. The numerical simulation using turbulence model Shear Stress Transport (SST k-?) produced satisfactory results when compared with experimental results of the modified turbine and classical Savonius turbine. For validation purpose, the modified model was tested in Universiti Teknologi Malaysia’s low speed wind tunnel at different flow velocities. Important parameters such as torque, power and performance as well as the pressure distribution on the blades surfaces were measured at different angles of attack. Parametric study was conducted in six subsections, in which the modified turbine had been investigated and analysed. The maximum coefficient of power of ReT was found to be 0.34 at tip speed ratio (?) of 0.9. This is 52% improvement in efficiency (power coefficient) compared to classical Savonius turbine without any extra accessories. The use of ReT will enable power to be extracted more efficiently from low speed marine currents.
A new algebraic tool for simultaneous targeting and design of mass exchanger network
(Universiti Teknologi Malaysia, 2020) Oladosu, Wasiu Ajibola
Process effluent recovery can be a potential source of revenue as well as an effective way to reduce the environmental footprint for industrial processes. In addition to sustaining business profitability, modern day industries have to fulfil their social responsibility by contributing toward environmental conservation and sustainable development. Mass (or materials) integration is a methodology for systematic and efficient reuse and recycling of materials in a closed loop within a mass exchange network (MEN). The integration of systems and processes promotes manufacturing synergy and minimises waste generation, disposal, and reduces the use of fresh materials and mass separating agents. Methodologies for MEN design and targeting include insight-based graphical and algebraic techniques as well as mathematical programming approaches. This study presents a new algebraic tool for simultaneous targeting and design of mass exchanger network that overcomes the limitations of previously developed mass integration approaches such as composition interval table (CIT), graphical composite curves (CCs) and grid diagram for MEN. The current CIT and CC cannot completely map individual rich and lean process streams, or individual process and utility streams. Hence, the mass separating agent (MSA) targeting results cannot be used to simultaneously design the MEN. Although pinch-based tools have been established for MEN design, the procedure is typically done in two sequential stages. The first stage involves MSA targeting using CIT. Once the targeting stage is completed the MEN design to achieve the MSA target is done using grid diagram. As the CIT cannot be used to visualise the MEN, repetitive stream-wise composition and mass load balance calculations have to be done in order to achieve the minimum MSA and number of mass exchange units. The aforementioned significant limitations of the conventional pinch-based approach have been overcomed by the newly developed segregated composition interval table (SECIT) proposed in this research. SECIT represents mass cascade along composition intervals for lean and rich individual streams. SECIT can help identify pinch point(s), determine utility targets and conduct SECIT mass allocation (SMA). The SMA can be converted to a SECIT network diagram that represents the MEN in terms of mass exchange quality and quantity, on the interval composition scale. Economic analysis study showed that the total capital cost target for MEN based on the newly developed SECIT is USD 752,539. This total capital cost target agrees with those obtained using conventional composite curves. However, sensitivity analysis study carried out using various minimum composition differences showed an optimal total cost of USD 448,945 and was found at minimum composition difference of 0.0001. Furthermore, sensitivity analysis study based on selection of materials of construction showed that 303 stainless steel type is the best material of construction for the newly SECIT network design. Four case studies, including an industrial application had been presented to demonstrate the validity and advantages of the proposed approach. This study shows that the SECIT and segregated network design can be an essential blend of algebraic and graphical visualisation tools for simultaneous MEN targeting and design of simple and complex processes and for retrofit cases involving threshold problems, stream splitting and multiple pinches.
A new viscoelastic damper for seismic protection of steel building frame
(Universiti Teknologi Malaysia, 2017) Mansour, Farnoud Rahimi
Viscoelastic dampers (VEDs) are widely used to protect structures against earthquake. Conventional VEDs are generally installed within a diagonal brace configuration which provides a stiff structural system and reduces their effectiveness. In addition, the aforementioned configuration is not suitable for retrofitting purpose and violates architectural requirements. In this study, a new type of viscoelastic damper is proposed in order to improve the seismic performance of steel structures and to overcome the drawbacks of the conventional VEDs. In order to evaluate the performance of the proposed VED, dynamic responses of a 3-story scaled down steel frame equipped with the proposed VED were obtained experimentally and numerically under harmonic excitations. In this stage, ABAQUS software was used to establish a detailed finite element analysis. The results obtained were compared with a frame equipped with the conventional VED as well as a moment resisting frame and braced frames. The effects of the size of viscoelastic layer on its dynamic characteristics were also investigated. In addition, a nonlinear time history analysis of a 10-story full scale steel frame was performed using SAP2000 software to demonstrate the effectiveness of the proposed VED for tall buildings. The results of this study showed that the frames equipped with dampers performed better than the braced frames in terms of reduction in the maximum displacement, acceleration and base shear responses of the 3-story moment resisting frame. Compared to the conventional VED, the proposed VED was more effective in reducing displacements, while it was slightly less effective in reduction of accelerations and base shears. It was also found that smaller thickness of the viscoelastic layer decreased displacement responses, however, it increased acceleration and base shear responses. The larger cross-section area of the viscoelastic layer resulted in smaller displacement responses, but larger acceleration and base shear responses. Thus, analysis of the 10-story frame showed that the effectiveness of VEDs for reducing maximum displacement and acceleration responses were strongly dependent on the characteristics of earthquake records. The proposed VED was more effective in reducing responses of the lower floors. Based on the results obtained, the maximum base shear response of the frame equipped with the conventional VED was smaller than the frame equipped with the proposed VED and larger than the bare frame regardless of the characteristics of earthquake records. The results showed that the viscoelastic dampers have more advantage in preventing the formation of plastic hinges in the frames even under severe earthquake. In addition, compared to the conventional VED, the proposed VED resulted in less damage to the structural members due to less plastic hinge formation. Therefore, the implementation of the proposed VED can overcome the deficiency of the VED in seismic protection of structures.
A structural model for cost effective building maintenance through design for maintainability
(Universiti Teknologi Malaysia, 2016) Ganisen, Shubashini
Building maintainability is renowned in the lack of integration with building design. This has been seen as one of the major factors contributing to various problems facing the building industry, precisely the increasing building maintenance costs. Initial study and critical reviews on literatures reveals that there is a need to identify a comprehensive building design for maintainability criteria and indicators to reduce the overwhelming cost of building maintenance through mitigation of defects. To address the above issues, this research was carried to establish an exhaustive building design for maintainability criteria and indicators to achieve cost effective building maintenance. Total of nine design for maintainability criteria, thirty-eight indicators and eighteen cost effective building maintenance indicators were identified and validated in two phases of survey and analysis. In the first phase, Delphi survey was conducted and in the second phase Structural Equation Modeling (SEM) technique was used to validate, develop and determine the structural model of building design for maintainability for cost effective building maintenance. This research aims to address the long pending quest of incorporating maintainability during the building design phase and form as basis to promote facility management practices in the building design phase. The results of this research firmly established the structural relationship model among building design maintainability criteria and indicators to achieve cost effective building maintenance. The structural model developed through this research can greatly benefits and being a useful reference in the construction industry particularly for the architects and designers to incorporate maintainability during the building design phase to achieve cost effective building maintenance
A structured critical success factors model for the implementation of green retrofit projects
(Universiti Teknologi Malaysia, 2015) Jagarajan, Rehmaashini
Existing buildings contribute to half of all annual energy and greenhouse gas emissions. Green retrofit has been the latest value added service under the facility management field to mitigate climate change caused by greenhouse gas emission. Yet, green retrofit implementation is not widely practiced by existing building stakeholders due to lack of participation and cooperation among them. Among the issues of green retrofit are high upfront costs and uncertain return, lack of green building professionals, lack of financial incentives, knowledge gap in green development quantification, lack of green awareness, lack of communication among the stakeholders, lack of internal leadership and lack of green materials and technology. These factors contribute to the failure of green retrofit projects' implementation. Thus, the aim of this research is to identify the critical success factors (CSFs) of green retrofit projects' implementation. The specific objectives of this research are: to identify the CSFs of green retrofit; to evaluate the criticality and ranking of CSFs of green retrofit; and to develop structural model for the CSFs of green retrofit. The research methodology adopted to achieve the aim of this research is quantitative method using a survey based approach consisting of three steps namely literature review, experts' opinions and questionnaire survey. Based on literature review, eight CSFs with thirty three indicators of green retrofit implementation were identified. Experts' opinions were sought to validate the identified CSFs and to develop relationships among the CSFs using an Interpretive Structural Modelling (ISM). Questionnaire survey was conducted to empirically confirm the ISM-Based Model using Structural Equation Modelling (SEM). The final model consists of eight CSFs with twenty seven indicators with CSF 1 (green building professionals) and CSF 5 (internal leadership) being the major drivers for the success of the green retrofit projects implementation
A systematic mathematical modelling framework of a cement plant optimisation
(Universiti Teknologi Malaysia, 2018) Ishak, Siti Aktar
Climate change has been a challenge from past decades with the increase of worldwide industrial activities. Cement industry is considered as one of the industries that generate high carbon dioxide (CO2) emissions. With imminent increase in CO2 emission due to the increased cement demand, a systematic model for cost optimal cement plant that fulfills carbon limitations without compromising product specification was proposed. Three sub-objectives were identified; to determine highest CO2 reduction and process synthesis of energy efficient technologies of an optimal cement plant, to perform economic assessments to study the feasibility of proposed methods, and to develop a dynamic simulation model of post combustion absorption unit capture system for cement plant. Three mitigation methods were considered; coprocessing, kiln system improvements, and carbon capture. Superstructure was constructed for the mixed integer linear programming model executed in an optimisation software called general algebraic modelling system. Cement plant with co-processing managed to mitigate 4% of CO2 emission with 94.67 USD/tonne clinker, 14% reduction was achieved with additional kiln improvements at USD 94.61/tonne clinker while the addition of carbon capture managed to be reduced up to 98% CO2 emission with USD 135.96/tonne clinker. Since more than 90% CO2 emission from cement plant was mitigated from post combustion capture system, the absorption column of the capture system was modelled for dynamic study. Dynamic rate based model of the absorber unit was coded into a simulation model called gPROMS. The rate based model consists of mass and heat transfer, chemical reaction and kinetics, and thermodynamic equilibrium (chemical and phase equilibrium). Ramp test was used to study the dynamic model. This study proves that the optimal results from the models can successfully improve the cement plant in terms of environmental criteria. The dynamic simulation model also shows smooth response to fluctuations of flue gas emissions from cement plant which could be integrated with CO2 capture process
Accident prevention model for the building construction industry
(Universiti Teknologi Malaysia, 2019) Samuel, Williams Opeyemi
The construction industry is often associated with accidents, resulting in partial or permanent disability, damage of property, loss of lives and income as well as poor company‘s image. The previous models of accident prevention developed in other countries could not be utilized on construction sites in Nigeria due to the lack of effective health and safety regulations. Hence, another model that incorporates the duties of construction stakeholders is needed for the construction industry in Nigeria. Therefore, this study was carried out under four objectives; to identify the types and frequencies of accidents occurring at the building construction sites, to determine the appropriate preventive measures at the pre-construction stage against the occurrence of accidents, to determine the appropriate preventive measures at the construction stage against the occurrence of accidents, and to develop a valid and practicable model for the prevention of accidents at the building construction sites in the South-western zone of Nigeria. In order to achieve the objectives of the study, three stages of survey methodology were conducted through administration of questionnaires and interview sessions with selected respondents. Stage one involved the distribution of questionnaire on 310 respondents to survey the types and frequencies of accidents, stage two involved the use of questionnaire on 384 respondents and interview protocol on 14 experts to find out accident preventive measures and health and safety-related regulations, while stage three utilized questionnaire on 24 experts for validation of the model. In addition, mean scores, t-test, Mann-Whitney U test and structural equation modelling tools were used for analysis of the collected quantitative data, while the qualitative data were analysed with the aid of NVivo software using thematic analysis. The findings of the study showed that four categories of major accidents occurred on the building construction sites; contact with objects, vehicle/machine-related accidents, slip and trip, and fall-related accidents. Besides, there was no significant difference between the accidents occurring in low-rise buildings and those occurring in high-rise buildings. Moreover, 40 accident preventive measures were found to be significant, having 17 and 23 preventive measures at the pre-construction stage and during the construction stage respectively. Furthermore, the 40 significant preventive measures were pooled together to develop a model for the prevention of accident. In order to establish the validity of the model, the contacted construction and safety experts supported the validity, appropriateness and easy comprehension of the model. The ability of the model to provide a guide to the construction professionals was also attested to by the experts. In addition, the dual-stage accident prevention model is vital in enabling the stakeholders to possess the cognizance of individuals‘ safety roles during the pre-construction and the construction stages. The proposed model is also deemed applicable for use not only in Nigeria, but also other parts of the world to decrease on-site accidents.
Acoustic characteristics of deformable origami structures for multi-purpose hall
(Universiti Teknologi Malaysia, 2020) Muarat, Nurul Farhanah
In the multi-purpose hall, variable acoustic elements are required to vary the acoustics of the space tailored to the intended use. The variable acoustics elements are normally achieved by the variable absorption, variable volume and active acoustic system and have been successfully implemented in many halls. However, there is a necessity to explore other innovative variable acoustic elements in order to improve knowledge in this field. In the engineering field, the origami-inspired structures that are made up by folding a flat sheet of material to three-dimensional structures have been an increasing topic of interest among researchers in various applications. The applications range from sandwich structures to mechanical metamaterials and the interest is due to the intriguing characteristics that possessed by the origami-inspired structures. For that reason, this research proposed deformable origami structure as an element that can vary the acoustic condition. To realize the research ideas, comprehensive experimental works were carried out to investigate the feasibility of origami structure as variable acoustic element. Two types of origami patterns namely Triangular and Miura origami fabricated using three different materials (i.e. paperboard, felt and ethylene-vinyl acetate foam material) were investigated in this study. The origami structures were characterized by the absorption coefficient through sound absorption tests in a 1:5 scaled reverberation chamber. The 1:5 scaled reverberation chamber is compiled to ISO 354 (2003) which qualified the chamber to conduct sound absorption measurement. The origami structures were tested in a reverberation chamber by varying the height of the structure to simulate origami deformation using the perimeter-to-area (P/A) ratio method. The result shows that the origami structure has the ability to change the sound absorption characteristic by changing the height of the structure. However, the choice of material used to construct the origami structure has a significant influence on the effectiveness and the frequency range in which the absorption coefficient is altered. The study also shows that the size of the sample plays a critical role in the determination of the absorption coefficient as it introduces the edge effect to the test result. A case study performed in this study also indicated that the utilization of deformable origami structure can vary the acoustics
Acoustical characteristic changes due to transverse rumble strips installation on roadway
(Universiti Teknologi Malaysia, 2020) Darus, Nadirah
Transverse rumble strips (TRS) acts as a traffic calming device to alert inattentive drivers through the optical, sound and vibration effects. Currently, the existing TRS guidelines have been found to be very basic with no detailed explanation on the TRS profile. Inappropriate design of TRS profile may generate excessive external noise level that can affect the nearby residents. Besides, the real cause of TRS roadside noise annoyance is still unknown. Therefore, this study aims to evaluate the acoustical characteristic changes due to TRS installation at residential areas in contributing to the framework of optimum TRS design selection for future installation. The objectives of this study are to investigate current TRS designs and characteristics, determine road and traffic characteristics at selected roadways, evaluate noise annoyance due to TRS installation and develop empirical model of TRS roadside noise level for the proposal of framework of optimum TRS design selection. Visual investigation and on-site measurement were conducted to investigate the current TRS design and characteristic. Measurement of road and traffic measurements were also carried out to evaluate the skid number (SN), vehicle speed, traffic volume and composition that may affect sound level changes. This study measured the external noise generated by a range of gross vehicle weight (GVW) between 850 kg and 7700 kg which travel over three types of TRS, namely middle overlapped (MO), middle layer overlapped (MLO) and raised rumbler (RR) with speed range of between 30 km/h to 70 km/h. Controlled pass-by (CPB) method was conducted to determine the sound level changes. Actual traffic condition due to TRS installation was also measured. Meanwhile, assessment of sound level changes and impulse, low frequency noise (LFN) and tonal, noise limit and traffic noise index (TNI) were carried out to assess the noise annoyance from TRS. Statistical analyses were used to test all related variables of roadside noise level due to TRS. Significant variables were used for the development of empirical noise models by using multiple linear regression. Then, framework of optimum TRS selection design was proposed to assist local authorities for future TRS installation. TRS thickness was limited to 3 mm for all profile types. TRS roadside noise may affect nearby residents as the sound level increment was more than 6 dBA. The sound level changes for vehicles transit on MLO were higher than MO and RR of more and less than 3 dBA, respectively. Besides, MLO showed the most significant impulsivity regardless of the multiple vehicles transit. TRS roadside noise was also characterized by LFN at frequency region of 20 Hz to 125 Hz. Tonality was also found significant especially due to heavier vehicles with GVW of 5000 kg and above at speed of 50 km/h. Among the three types of TRS, MO showed the best performance due to its insignificant acoustical characteristics. SN, vehicle speed, traffic volume and GVW were found to be significant variable for the generation of TRS roadside noise level. Meanwhile, other variables, such as TRS width, length, spacing, profile and strip number, traffic volume and skid resistance were found insignificant. The established empirical models based on the real causes of TRS noise annoyance were used in the proposal for framework of optimum TRS design selection for future installation. This proposed framework could enable exploration of TRS impact on the traffic noise condition to facilitate the local authority on the best selection of TRS type during the surround area become critical for noise annoyance.
Active vibration control of vortex induced vibration on segmented cylindrical marine riser model
(Universiti Teknologi Malaysia, 2016) Mohammed, Mohammed Jawad
The interaction between the bluff structures and the fluid flowing in perpendicular direction that leads the body to vibrate in cross-flow is called vortex induced vibration (VIV) that considers the main factor lead to the structure failure. Two suppression control strategies have been studied which are; passive control that depends on increasing the stiffness or mass without using external power and active control that depends on employing the sensors and actuators with feedback system to cancel the effect of VIV on the structure. In this research, an experimental setup of segmented cylindrical marine riser model caused by VIV is designed, developed and fabricated as a platform for the active controller development and verification. The experimental rig is used to collect the flow speed as input data and cylinder vibration amplitude as output data. Nonlinear system identification (SI) techniques were employed to model the nonlinear dynamic behavior of the cylindrical structure subjected to VIV which are; neural network based on nonlinear auto-regressive external (exogenous) input (NN-NARX), nonlinear auto-regressive (NN-NAR), nonlinear input-output (NN-NIO) models and adaptive neuro-fuzzy inference system (ANFIS) which were employed using superior NN-NARX model due to lowest mean square prediction error (MSE) of 1.1041×10-6. Next, PID based controllers tuned by heuristic method, particle swarm optimization (PSO) and iterative learning algorithm (ILA) were developed to control the unwanted vibration. In addition, Fuzzy-PID (FPID) controller was also developed as an intelligent controller. Based on the simulation results, PID-PSO has recorded the lowest MSE of 9.2659×10-5 reduction of 79.75 % as compared to the other controllers. For experimental validation, passive control is implemented to see the effect of double control rods at two locations on the cylinder and the results revealed that the cylinder remains vibrated for both of cases. Thus, active open and close loops vibration controls have been implemented to reduce the marine riser deflection via double control rods driven by double motors 12 V. Initially, an active open loop control technique was applied via proposed motors based on the rotational direction clockwise CW and counter clockwise CCW. Then, four voltages (6 V, 8 V, 10 V and 12 V) are supplied to the electromechanical motors to derive double control rods in the best direction (CCW). Finally, an active close loop control verified by the best optimized controllers PID-PSO, PID-ILA and FPID based on simulation results are employed to attenuate the undesired vibration via control rods in two positions driven by electromechanical motors. As a result, all types of controllers were able to suppress the vibration. However, PID-PSO controller is more superior as compared to the other approaches with vibration suppression of 66% on the vibrating marine riser
Activity-based life cycle cost process model for facilities maintenance of public universities
(Universiti Teknologi Malaysia, 2014) Thanaraju, Puvaneswary
Facilities maintenance is an essential part in the whole process of building maintenance and management. Maintenance period spans through the life cycle of a building hence, more attention is required in terms of financial management and good recording keeping. The application of life cycle cost in facilities maintenance is still limited caused by the complexity and variation of assets. The study develops the Activity-based life cycle cost process model for public universities (Research Universities) in Malaysia in order to provide an effective cost management in building facilities maintenance. Data for the study was based on a questionnaire survey and interview granted by some senior maintenance officers and experts in the building industry. Findings from the study show that the institutions varied in the level of importance they attached to the various facilities in a building in terms of financial allocation for maintenance. Those facilities that have been accorded much priority based on the results from the study were used in developing a process model of Activity-Based Life Cycle Cost (AB-LCC) of facilities maintenance at public university. The findings show that the AB-LCC process model was defined clearly across every facility maintenance activities with the clarity of cost drivers. Aggregating all activities together under a unit during the financial allocation does not give room for accountability and efficiency in building maintenance of public universities in the country. The application of AB-LCC has policy implication for both government and public universities because of the competing needs they will face with and the need to allocate resources in a way that the desired result would be met
Adaptive optical feedforward linearization of optical transceiver for radio over fiber communication link
(Universiti Teknologi Malaysia, 2018) Neo, Yun Sheng
With the tremendous growth in numbers of mobile data subscribers and explosive demand for mobile data, the current wireless access network need to be augmented in order to keep up with the data speed promised by the future generation mobile network standards. Radio over fiber technology (RoF) is a cost effective solution because of its ability to support numerous numbers of simple structured base stations by consolidating the signal processing functions at the central station. RoF systems are analog systems where noise figure and spurious free dynamic range (SFDR) are important parameters in an RoF link. The nonlinearity of a laser transmitter is a major limiting factor to the performance of an RoF link, as it generates spurious spectral components, leading to intermodulation distortions (IMD), which limit the achievable SFDR of the analog RF wave transmissions. The device nonlinearity can be mitigated through various linearization schemes. The feedforward linearization technique offers a number of advantages compared to other techniques, as it offers good suppression of distortion products over a large bandwidth and supports high operating frequencies. On the other hand, feedforward linearization is a relatively sensitive scheme, where its performance is highly influenced by changing operating conditions such as laser aging, temperature effect, and input signal variations. Therefore, for practical implementations the feedforward system has to be real-time adaptive. This thesis aims to develop an adaptive optical feedforward linearization system for radio over fiber links. Mathematical analyses and computer simulations are performed to determine the most efficient algorithm for the adaptive controller for laser transmitter feedforward linearization system. Experimental setup and practical measurement are performed for an adaptive feedforward linearized laser transmitter and its performance is optimized. The adaptive optical feedforward linearization system has been modeled and simulated in MATLAB Simulink. The performances of two adaptive algorithms, which are related to the gradient signal method, such as least mean square (LMS) and recursive least square (RLS) have been compared. The LMS algorithm has been selected because of its robustness and simplicity. Finally, the adaptive optical feedforward linearization system has been set up with digital signal processor (DSP) as the control device, and practical measurement has been performed. The system has achieved a suppression of 14 dB in the third order IMD products over a bandwidth of 30 MHz, in a two-tone measurement at 1.7 GHz.
Advancement of electro-mechanical dual acting pulley continuously variable transmission using independent actuators
(Universiti Teknologi Malaysia, 2017) Mazali, Izhari Izmi
Electro-Mechanical Dual Acting Puley Continuously Variable Transmision (beter known as EMDAP CVT), developed in Universiti Teknologi Malaysia, features two actuators: a primary puley actuator (consists of a primary DC motor and a set of primary power screws mechanism) and a secondary puley actuator (consists a secondary DC motor and a set of secondary power screws mechanism). To vary CVT ratio (rCVT), the position primary puley sheaves (Xpri) is adjusted by the primary puley actuator, while the position of puley sheaves (Xsec) is changed by the secondary puley actuator depending on Xpri position. Such dependency, unfortunately, causes a complicated proces to vary rCVT since it involves two DC motors, two position sensors and an algorithm convert Xsec based on Xpri. Hence, the objective of this research is to develop independent actuators (IA) for EMDAP CVT so thathis complication eliminated. IA consists of a ratio actuator that comprises a DC motor (ratio motor) adjust both Xpri and Xsec to vary rCVT, and a clamping force actuator that comprises a DC motor (clamping motor) actuate only the secondary power screws Xps_sec) for CVT belt’s action. This research is divided into thre phases: namely, the design phase, the analyses phase, and thexperimental phase. The aim of phase is to finalize the design concept of EMDAP CVT with IA. Here, relevant criteriand requirements for the concepts are identified; then, five design concepts are introduced. The final concept iselected based on the asesments of al using the House of Quality. Next, the objective of analyses phase is to study the significance the non-linearity betwen Xpri and Xsec during the changing of rCVT as a preparation for the prototype’s development. This non-linearity compensated by disc springs in secondary puley, thus it is defined as changes in the disc springs’ deflection, ?S. Minimizing ?S is crucial to minimize the variation the clamping force, maximize the springs’ lifespan, friction works and avoid excesively high ratio motor’s torque. Based on mathematical equations for varying rCVT, the relationships betwen ?S and CVT belt’s pitch length (L) ratiof Xpri:Xps_sec are investigated within rCVT of 0.60 to 3.0. Thevaluated Ls are 645m (Belt Type 901018) and 610m (Belt Type 901057) and from these, the later iselected since it reduces ?S by about 23% as compared to the former. The investigation also shows that can be furthereduced by around 36-45% by using Xpri:Xps_sec of 1:0.9, as oposed to 1:1. These findings are used finalize the concept’s parameter for the prototype development. Finaly, the objective of thexperimental phase is to prove the workability of EMDAP CVT with IA. In thexperiment, the prototype capable of varying rCVT from circa 0.60 to 3.0 by using only ratio actuator and the experimental data ?S show very smal diferences with analytical data, ranging from -0.05m to 0.3m. As a conclusion, EMDAP CVT with IA has ben sucesfuly developed, and it eliminates the dependency betwen two actuators the original EMDAP CVT, thus making rCVT varying procesignificantly simpler
Aerated concrete from agro-industrial waste for improvement of thermal insulation buildings
(Universiti Teknologi Malaysia, 2015) Aminudin, Eeydzah
Malaysia, a tropical country having a warm-humid climate year round has caught an eye in the development of construction buildings. These inevitable interactive, affects the climate sensitive approach which could be control by adapting the waste as building material that can reduce the heat transfer towards the impact of temperature elevation that could cause the Urban Heat Island (UHI) effects. Hence, this study emphasize on the Agro-Industrial (Palm Oil Fuel Ash (POFA) and Bottom Ash from Coal Power Plant (BA)) wastes as an aerated concrete to enhance the insulation performance and thermal behaviour for preventing heat energy internally. The study comprises mix design of the aerated concrete with the aim of replacing 100% sand with BA and POFA as cement replacement with ratios (0, 10, 20 and 30%). The engineering properties analyzed include strength, density, thermal conductivity, porosity, and pore size distribution as potential insulator of non-load bearing concrete. Porosity and pore size distribution were determined by using the Mercury Intrusion Porosimetry. During the initial stage, the development of 100% BA as sand replacements were developed, continue by replacement of cement with POFA of different percentage. Next, the ambient temperature, surface temperature, solar radiation and relative humidity were measured every fifteen minutes for seven days. The material which exhibits low thermal conductivity, with acceptable compressive strength, good insulation properties and heat storage has been chosen for the second stage experiment. At this stage, 30 per cent of POFA (30POFA) was selected to be compared with commercial aerated concrete and the OPC Mortar. The optimum mix proportion of 30POFA is 1:1:2 (cement: lime: bottom ash), with the water dry mix of 0.29, with 1% superplasticizer and 1.5% aluminum powder. The results showed that the strength of 30POFA, 5Mpa at 28days for air cured with the density of 1226 kg/m3. Besides that, 30POFA exhibits fastest rate of heat absorption and huge amount of heat storage with time lag of 122 minutes which is 40% longer compared to 0POFA. However, 30POFA depicts slightly hotter internally (indoor) compared to commercial aerated concrete, since it is good in insulation. As for thermal conductivity, 30POFA has achieved 0.48W/mK, which is 73% reduction in thermal conductivity compared to OPC Mortar, whereas 24% reduce compared to Control Sand. As for heat transfer mechanism, 30POFA have a high peak of heat flux during mid day of 16 W/m2 and recorded lowest during night time of (3 W/mK) compared to commercial aerated concrete of (5 W/m2) mid day and 8 W/m2 at night. This proves that 30POFA have longer heat storage in mid day, and the heat (Qconv) does not release out to the atmosphere during night time. Overall, 30POFA or known as Agro-Industrial aerated concrete is proven to be reliable material for non-load bearing wall of building as Urban Heat Island mitigation

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