Pusat Pengajian Sains Fizik - Tesis

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Modelling Of Potential Field Data For Shallow Thermal And Crustal Structure Beneath Peninsular Malaysia
(2022-12)
Yaro, Usman Yahaya
This thesis has taken advantage of the global compilation of potential field data to derive the first regional thermal structure as well as the most resolved crustal thickness model for the entire Peninsular Malaysia and neighbouring regions. Bore-hole heat flow data can provide the most precise information about the thermal structure of the crust, but these measurements are extremely difficult to obtain (expensive, sparse, and limited to shallow depths). The depth to bottom of magnetic sources (DBMS) has traditionally been used as alternative to surface heat flow data. In this study, DBMS are derived assuming random uncorrelated and fractal magnetisation models. DBMS using fractal distribution of sources (~ 17 – 46 km with a mean of 29 km) are found to be lower than the values computed using conventional random method (29 – 67.4 km with a mean value of 49.3 km) and reasonably well while considering other tectonic and geophysical constraints. Despite, the differences in the derived DBMS for the two methods, visual inspection and cross plots shows that they are linearly correlated, and they have the same pattern and trends. Crustal thickness for the study area varies from ~ 27.4 – 34.6 km with an average of 30.8 km. A comparison between the derived DBMS and crustal thickness shows that the upper mantle beneath the west Sumatra, Singapore, Malay basin, NW Peninsular Malaysia, and southern Thailand are significantly magnetised. The presence of magnetic upper mantle point to the stability of these regions attributable to low heat flow, geothermal gradient, and serpentinization.
Black Silicon Fabricated By Silver-Assisted Chemical Etching For Flexible Solar Cells
(2023-03)
Omar, Halo Dalshad
Monocrystalline silicon (mono c-Si) dominates more than 90% of photovoltaic market due to increasing solar cell efficiencies, technology maturity and reducing technology cost. Currently, photovoltaic manufacturing uses solar cells with 180 μm thickness. To reduce the technology cost, one promising strategy is by reducing the c-Si wafer thickness below 100 μm, whereby the wafer becomes flexible. Furthermore, flexible c-Si introduces new features including flexibility, light weight and makes thin c-Si highly attractive for flexible solar cells. Most importantly, thin c-Si solar cells usually demonstrate higher open circuit voltage (Voc) due to the lower bulk recombination and more efficient electron-hole pair extraction. However, one big challenge of the thin c-Si is the insufficient light absorption due to the indirect bandgap of the c-Si. Additionally, planar c-Si exhibits a high broadband reflection of around 35% within 300-1100 nm wavelength region, which further reduces the light absorption in the c-Si. To improve the light absorption in the thin c-Si wafers, black silicon (b-Si) offers a great potential for solar cell application since it yields a superior broadband light absorption within 300-1100 nm wavelength region. This is attributed to refractive index (n) grading effect,
Deformation Monitoring Of Marwat-Khisor Ranges, Pakistan Using Interferometric Synthetic Aperture Radar
(2023-02)
Fadzil, Fakhrul Hazwan Ahmad
Main Frontal Thrust (MFT) represents the southern boundary of Himalaya, which accommodated the current orogeny of Eurasian-Indian tectonic plate’s convergence. The deformation pattern and structural style of MFT are crucial for understanding the tectonic activities. A chain of fold-and-thrust (FAT) belts (Salt-Trans Indus Ranges) are identified as the MFT in the western Himalaya. The Salt Range had propagated southward at an average rate of 5-10 mm/year in the influence of salt tectonics. Although the Trans Indus Ranges had indicated an active Quaternary tectonics, the fault slip rate and direction was unknown. This study focused on the Marwat-Khisor Ranges (a segment of Trans Indus Ranges), the youngest part of the MFT in the western Himalaya. Remote sensing techniques such as Interferometric Synthetic Aperture Radar (InSAR) Permanent Scatterer (PS), lineament extraction and geometric analysis of salient were implemented to investigate the deformation mechanisms and active tectonics. InSAR processing of 80 Sentinel-1 images showed the Marwat-Khisor Ranges were uplifting in the satellite line-of-sight at an average rate of 3-7 mm/year dated from 18th October 2014 to 18th June 2019. The Marwat-Khisor Ranges are the hanging wall sequence that ramped up section above the partially emergent Khisor Thrust where surface uplift is expected.
Study Of Biostimulation Effect On Normal And Anaemic Human Blood Cell Irradiated By 589 nm And 532 nm Laser
(2019-04)
Fauzi, Nabihah
Laser (light amplification by stimulated emission of radiation) is a monochromatic light. It has been widely used in various fields including in the field of medicine. Application of Low Level Laser (LLL) at low output power (1-500 mW) has been proven to have therapeutic or biostimulation effects on biological tissues or cells. Widespread applications of LLL in medical practices including blood irradiation have resulted in the investigations on the bio-stimulation effects on irradiated human red blood cell (RBC). In this study, full blood count was measured on normal and anaemic human blood, the morphology of RBC were compared and the adenosine 5’-triphosphate (ATP) values were analysed.
Simulation And Performance Studies Of Thermally Efficient Light Emitting Diodes Drivers
(2018-09)
Mohd Supian, Norazlina
The thermal behaviour of an electronic package is often characterized by evaluating the junction temperature and thermal resistance at the junction of a single or multiple heat source to ambient. In the case of IC LED drivers, the heat source within the device is either single or multiple due to presence of many integrated component such as transistor, internal resistor, etc on a single die. Hence the evaluation of IC drivers with single or multiple heat sources is absolutely necessary for imparting suitable thermal management within the device. In this study, thermal transient measurement method and computational fluid dynamics (CFD) simulations have been used to measure thermal resistance and junction temperature.

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