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Modeling and investigation of combined darrieus and vane design vertical axis wind turbine
Get PDFDoctor of Philosophy in Manufacturing EngineeringWind energy is one of the potential sources of renewable energy because of its abundance
in the atmosphere. It is available in different scales of high, medium and low-velocity
ranges. Wind power is a major source of sustainable energy, which can be harvested by
Horizontal Axis Wind Turbines (HAWTs) and Vertical Axis Wind Turbines (VAWTs).
VAWT can be used in low wind speed regimes for performing various small-scale
functions ranging from electrifying a building’s equipment. In this thesis, the
performance of a newly designed vertical axis wind turbine for application in urban areas
is presented. The proposed new design is a combination of vane type rotor and a vertical
straight-bladed Darrieus rotor (NACA 0012 airfoil) on the same axis. This design
combines the advantages of both designs while attempting to reduce the disadvantages.
The vane type rotor creates high torque and is self-starting even at low wind speed but
with a relatively low-efficiency rating. The Darrieus rotor has poor performance on selfstarting
rotor but has much higher efficiency than the vane type rotor. The combination
of the two rotors, vane type and straight-bladed Darrieus airfoil NACA 0012 increases
the total power of the turbine at lower wind speeds. A combination of Vertical Axis Wind
Turbine (VAWT) rotors was designed and tested in a subsonic wind tunnel. The proposed
new combined design increases the turbine output power in low wind speed areas of
above 4 m/s while solving the low starting torque problem for a Darrieus wind turbine.
The results showed that the new design could achieve the highest power coefficient of
= 0. 24 for a vane type wind turbine at wind velocity of 6 m/s and tip speed ratio
= 0.223. In addition, the power coefficient for the combined designed wind turbine
increased to = 0. 3925 at the same wind velocity of 6 m/s and at a tip speed ratio
= 0. 75
Determinants of employee engagement among assistant registrars of public universities in Malaysia and moderating effect of age, gender and length service
No full textDoctor of Philosophy in ManagementEmployee engagement has received a great deal of attention in the last decade from popular business press, including consulting firms and practitioner community. They claim that employee engagement is a new human resource practice that can be used by
business organisations in order to cope with the uncertainty of competitive industrial conditions. However, in the academic community, the concept is still new. Therefore, the concept requires rigorous seminal studies for it to be validated. Given that practical interest in employee engagement which has outstripped the currently available research evidence, fundamental questions as which variables contribute the most to employee engagement and how and why they benefit individuals and organisations, still remain
unanswered. To examine this issue, grounded by Kahn’s psychological conditions
theory, job resources theory, employee commitment theory, leadership styles theory
and employee trust theory, this study proposes a new framework by decomposing
employee engagement. A total of 400 assistant registrars from twenty public
universities in Malaysia participated in this study. Data were collected through
questionnaires (survey monkey hyperlink). The Partial Least Squares approach to
Structural Equation Modelling (PLS-SEM) was the main statistical technique employed
in this study. The findings of the study revealed that psychological safety, rewards and
recognition, employee development, affective commitment, employee trust, normative
commitment and leadership styles were found to have a significant relationship with
employee engagement. The psychological meaningfulness, psychological availability,
employee communication and continuance commitment were not found to have any
significant effect on employee engagement. The moderating variables (age, and length
of service) were found to have partially significant relationship with employee
engagement. This study has successfully developed a framework, PREALEN, which
can be used by future researchers and practitioners to measure employee engagement
Design and development of microwave absorber using waste materials
No full textDoctor of Philosophy in Communication EngineeringSugarcane bagasse is a potential agricultural waste to design the pyramidal microwave absorber to be used in radio frequency (RF) anechoic chamber for testing application. An RF anechoic chamber is a shielded room covered with absorbers to eliminate
unwanted reflection signal. In this work, sugarcane bagasse from the sugar industry and rubber tire dust from tire wear have been used. Both of the wastes have lossy carbon
contents naturally, which has made them suitable as the raw materials for the
fabrication of the low cost microwave absorbers. The dielectric constant of the
sugarcane bagasse had been measured using the Dielectric Probe Technique and
Software of Agilent 85071E using Transmission Line Technique. Microwave absorbers
are made of two main components, a filler material that does the absorption, and a
material matrix to hold the filler. In dielectric materials, the most crucial properties that
enable them to be applicable as microwave absorbers are the dielectric constant and the
loss factor which is the dissipation of energy in the material. Generally, dielectric
material absorbers are fabricated by the combination of fillers in a polymer matrix. In
this work, the fillers are the agricultural waste which is sugarcane bagasse (SCB) and
rubber tire dust (RTD) from tire wear whereas the polymer matrix is unsaturated
Polyester Resin RP9509 (UPR) which is rigid, flexible and electromagnetically
transparent polymer. In this work, the sugarcane bagasse also has been mixed with
rubber tire dust (RTD) to investigate their performance. The microwave absorber using
sugarcane bagasse had been designed and simulated in the CST Microwave studio
software. The measurement of waveguide technique has been used to check the
reflectivity performance. The microwave absorber has been investigated in microwave
frequency range between 1 GHz to 18 GHz. The results show that the sugarcane
bagasse has the potential used as the base material in developing the microwave
absorber and can operate in that range of frequency successfully. The adding of the
filler which is rubber tire dust increased the performance of the microwave absorber.
These absorbers were designed on the basis of the wave attenuation and depth of
penetration data and their EMC performance was evaluated in terms of bi-static
reflectivity performance. The performance of the absorbers was found to be below -10
dB. The different concentration of the filler were being measured and the reflectivity
was found to be better then -20 dB when the increasing value of rubber tire dust were
added
Carbon foorprint for hostel construction using industrialised building system in Pauh Putra, Perlis
No full textMaster of Science in Civil EngineeringEmission of carbon dioxide (CO2) from construction sector has been estimated to contribute nearly 50% of total global emission. Identifying the sources of emissions and understanding their function and relationship to construction activities are essential if
not crucial, in mitigating this global crisis. Sustainability research has been initiated to reduce and eradicate the carbon emissions problem, especially in the construction industry. This study evaluates the carbon footprint of the main machinery and materials
used in constructing a five-storey hostel that implemented Industrialised building system (IBS) method in Perlis, Malaysia. A life cycle assessment (LCA) framework is used in conducting a partial LCA from pre-design to construction phase. LCA was
performed in accordance with the four-step which is goal and scope definition, inventory analysis, impact assessment and interpretation. It also used as a method to systematically analyse the environment assessment. Results showed that the five-storey
hostel in Pauh Putra,Perlis has obtained a total IBS Score of 73.4%. Theindirect carbon
footprint hotspots are coming from prefabricated sandwich panels manufacturing
factory, especially one which manufactured by boiler machine. During this process,
4.52 tonnes of CO2e are released by the machines. This is due to the extensive energy
used for steam heating and high engine rating for the boiler. Cement releases about
369.04 tonnes CO2e. Its direct carbon footprint hotspots are caused by the large quantity
of cement used in the shotcrete mixture and its high extraction–production CO2
emission values. Meanwhile, overall onsite materials generated 65.60% of the total
carbon footprint. Whereas, the direct carbon footprint hotspots by the fuel machinery at
the construction site were heavily from excavator and construction of building
superstructure task, which yields 81.59 tonnes CO2e and 86.76 tonnes CO2e,
respectively. This is mainly due to the extensive use of both types of machinery in the
daily construction activities. These results can be used as one of the samples in many
problems to determine an adequate understanding the impact of IBS construction to
carbon emissions in Malaysia
Amalan keusahawanan sosial Islam dalam kalangan usahawan: kajian terhadap usahawan sosial berjaya muslim di Malaysia
No full textDoctor of Philosophy in Social EntrepreneurshipSince research effort in the area is minimal, there is a clear need to examine the practice of Islamic social entrepreneurship (ISE) among successful Muslim social entrepreneurs (SMSE) in Malaysia. One such practice is to organize charitable activities to benefit the community through the gains made from entrepreneurial activities that are based on social mission and vision. However, the studies are not specific to models and concepts that could provide clear guidance to further enhance these practices so that they
coincide with the spirit of al-Maqasid al-Syariah. Hence, this study focuses on the
development of a conceptual model of ISE derived from the practices of SMSE. For this
study, five (5) specific objectives were drawn up, namely: (i) to review the concept of
social entrepreneurship from Islamic perspective, (ii) to identify the Islamic social
entrepreneurship practiced among successful Muslim social entrepreneurs in Malaysia,
(iii) to identify the implications of the practice in accordance with the Islamic
perspective of social entrepreneurship, (iv) to explore the factors surrounding the
involvement of successful Muslim social entrepreneurs in the activities of social
entrepreneurship and their challenges, and (v) to build a model of social
entrepreneurship that is based on Islamic perspective. Research methods employed in
the study are case study, content analysis, comparative analysis, expert consultation, and
interviews which would help to achieve all the objectives outlined. The study identified
13 concepts of ISE that need to be inculcated among SMSE, namely, the concepts of the
caliphate (Khalifah), fraternity, economic jihad, fairness and balance, meeting the social
needs of society, developing and improving the social value of the giver (contributor),
al-Falah, enjoining good and forbidding evil (Amar Makruf wa Nahi Munkar), social
security, the enhancement of the economy of the ummah, zakat and waqf, charity and
baraqah, and doa, prayers and regular attendance of the mosque. The ISE dimensions
have also been identified: faith (iman), taqwa, possessing admirable qualities
(mahmudah) and ihsan (kindness). Overall, 13 participants constituting eight SMSE and
five experts with religious academic backgrounds participated in the study. The results
showed that a total of five themes and 30 sub-themes for the SMSE and the academic
experts have been successfully analyzed based on the five research objectives. The
study found that all themes and sub-themes point to the importance of ISE be practiced
by the SMSE. This is because it is in line with the al-Maqasid al-Syariah and meeting
the ultimate quest of approval and blessings of Allah SWT in this world and the
hereafter. Thus, the model of ISE is the major contribution of the study which could
serve as guidelines for SMSE, particularly young entrepreneurs