Pusat Pengajian Sains Fizik - Tesis

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Environmental Impact Assessment Of Abrasive Materials In Industrial Blasting Process
(2024-09)
Amin, Iskandar Zulkarnain Mohd
The environmental impact study of abrasive materials in the blasting industry is a pivotal research endeavour. Abrasive blasting, widely used in surface preparation and painting industries, involves projecting high-pressure abrasive material onto surfaces. This research aims to characterize various abrasive materials and assess their environmental impact. Various proposed abrasive materials, including diamond, garnet, jadecut, ceramic, and two types of glass (Duragrit glass and Glass blast), undergo a meticulous examination of their compound composition and crystallinity, utilizing X-ray Fluorescence (XRF) and X-ray diffraction (XRD) analyses. Both Duragrit glass and Glass blast emerge as promising candidates, displaying an amorphous structure and meeting the Department of Occupational Safety and Health (DOSH) requirements for open blasting. Mechanical properties of these materials are thoroughly characterized, including particle size distribution (ISO11127-2), apparent density (ISO11127-3), hardness (ISO11127-4), moisture content (ISO11127-5), and water-soluble chlorides (ISO11127-7). For instance, apparent density measures 2.17 × 103 kg/m3 for Duragrit glass and 2.5 × 103 kg/m3 for Glass blast, with moisture content at 0.01%. Water-soluble chlorides are Nil for Duragrit glass and 0.0001% for Glass blast. These findings are foundational for effective abrasive blast-cleaning, ensuring safety compliance, and preserving desired surface features. The efficacy of Duragrit glass and Glass blast in surface preparation adheres to industry standards, meeting Petronas Technical Specifications (PTS) and Shell Technical Specifications (STS) requirements.
Multi-layer Radiation Shielding Design For Compact Proton Therapy System Using Monte Carlo Simulation
(2024-09)
Aliyah, Fitrotun
Proton therapy has emerged as a highly effective treatment for various cancers due to its precision in targeting tumor cells while minimizing radiation exposure to surrounding healthy tissues. However, the design of compact proton therapy facilities poses significant challenges, particularly in terms of shielding requirements, cost, and environmental impact. This study aims to develop a novel shielding design for proton therapy systems that complies with regulatory dose limits while reducing the overall cost and footprint by utilizing alternative materials through a multilayer structure model. The research begins with the characterization of natural aggregate and steel slag as potential alternative materials for concrete admixture, then continues with experimental evaluations of radiation attenuation properties using PuBe, LINAC, and CT-Scan as radiation sources. To further develop and optimize the shielding design, the study employed Monte Carlo simulations using the Particle and Heavy Ion Transport code System (PHITS). These simulations facilitated the creation of innovative shielding configurations, incorporating both single-layer and multilayer structures composed of Portland concrete (PC), steel slag concrete (SSC) , iron (Fe), borated polyethylene (BPE), and recycled high-density polyethylene (HDPE). The experiment results demonstrate that steel slag concrete offers superior radiation shielding performance compared to conventional concrete. The PHITS simulation results demonstrate that the material combination model of PC-SSC on the treatment room wall and PC-SSC-Fe-HDPE on the Maze 1 wall is the optimal configuration with ambient dose equivalent rate value ranging from 13 to 773 mSv/year.
Characterization Of Multilayer ZnO/METAL/ZnO As pH Sensor
(2019-07)
Rasheed, Hiba Saad
This study focused on the synthesis and characterisation of ZnO/metal/ZnO multilayer thin films for extended gate field effect transistors in pH sensor devices by using a physical method. Multilayer structures ZnO/metal/ZnO and ZnO single layer were deposited on glass substrate via radio frequency and direct current magnetron sputtering.
Optically Pumped Lasing Properties Of ZnO Nanorods
(2018-11)
Nordin, Muhammad Nuri
The purpose of this study is to investigate the characteristics of optically pumped laser from the ZnO nanorods grown by using the two-step chemical bath deposition (CBD). Samples are grown on two types of substrates, glass and sapphire wafer, AI2O3. Various conditions and treatments of the samples have been introduced to observe the optical emission mainly by manipulating the thickness of ZnO seed layer thin film and the heat treatment condition. The procedures for CBD process is fixed for four hours at 97“C for growth process with the solutions of 0.05 M of zinc nitrate (Zn(NO.3)2.6H2O) and 0.05 M of hexamethylenetetramine (11 MT).
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.

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