Pusat Pengajian Sains Fizik - Tesis
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- PublicationNumerical Analysis Of Atmospheric Aerosol Monitoring Using Horizontal Scanning Lidar(2025-02)Han, Joseph Ooi BoonAir pollution episodes like haze are common in countries exposed to high levels of air pollutants. In malaysia, haze occurs when high concentrations of atmospheric aerosols, especially particulate matter (pm), are produced from local and transboundary sources. Atmospheric aerosols can be monitored using air quality monitoring stations or atmospheric lidars. Lidars can potentially provide better atmospheric aerosol monitoring than air quality monitoring stations due to superior spatio-temporal resolutions and faster detection. However, horizontal scanning lidars in particular have yet to be implemented as aerosol monitoring tools because they are recently introduced. Furthermore, numerical models to establish empirical methods for using horizontal scanning lidars in continuous atmospheric aerosol detection and monitoring are unavailable. This study aims to present numerical analysis of atmospheric aerosol detection using horizontal scanning lidar. By evaluating haze detection models that analyze effects of pm present in haze on horizontal scanning lidar readings, effectiveness of horizontal scanning lidars in atmospheric aerosol monitoring can be assessed without physical units. Numerical assessment via comparative study method is first conducted to evaluate the performance of a hypothetical horizontal scanning lidar using single scattering theory.
- PublicationMonte Carlo Simulation And Experimental Validation Of Plastic Scintillator Performance For Radiation Detection(2025-02)Putro, Guntur EkoPlastic scintillators have been extensively utilised for detecting radiation in many different kinds of applications. In actual measurement, poor detection performance can lead to low detection efficiency, increasing the risk of overlooking harmful radiation and causing mistakes in diagnosis or monitoring exposure levels. To mitigate these challenges, efforts are required to enhance the detection efficiency, necessitating the development of a robust and validated simulation model to expedite this work. The monte carlo method is used in this work to develop detector model and determine parameter of a detector exposed to radiation sources with energies from 100 to 1300 kev. The plastic detector performance was modeled using mcnp, which included gaussian energy broadening (geb) adjustment for obtaining responses. The simulated outcomes were then compared to actual experimental data to determine accuracy. This
- PublicationPhotoelectrochemical Properties Of Titanium Dioxide Nanostructures Grown By Hydrothermal Technique(2025-02)Feng, TaixiangPhotoelectrochemical (pec) water splitting is a highly promising technique to convert solar energy into chemical energy by storing energy in the form of chemical bonds of the reaction products (h2 and o2). Additionally, h2 fuel is of great interest to meet the requirement of increasing energy consumption. In this work, anatase non-stoichiometric tio2 nanostructures transformed from titanates were prepared by the alkaline hydrothermal technique at different treatment durations (4h- 24h) and temperatures (130°c-210°c). The morphologies of samples were characterized by field emission scanning electron microscopy (fesem) and demonstrated that the morphological change of tio2 from nanosheets to nanowires. Also, the o/ti atomic ratio extracted from the edx data indicates that all the samples have indirectly shown non-stoichiometric structures with the formula can be presented as tio2-x because of the oxygen deficiency. The phase of tio2 nanostructures is confirmed to be anatase by x-ray diffraction (xrd) patterns. The optical properties of samples were measured by uv–vis-nir measurement and suggested that long-time duration and high temperature of hydrothermal treatment both caused the increase in the diffuse reflection. With respect to the pec properties, a three-electrode reaction cell made of tio2 photoanode, platinum wire and ag/agcl reference electrode was used to evaluate the performance of samples.
- PublicationEvaluation Of Radiation Dose For Common Computed Tomography Assessment In North Of Jordan(2025-02)Mahmoud, Albadarneh Laith KhaledThe increasing use of computed tomography (ct) necessitates careful evaluation of radiation exposure and associated cancer risks. This study investigates the lifetime attributable risk (lar) of cancer from radiation in common ct scans and analyzes dose variations across scanner protocols. Using the beir vii linear non-threshold (lnt) model and virtualdose™ monte carlo simulation software, organ and effective doses were estimated, and diagnostic reference levels (drls) were proposed to optimize radiation doses in jordan. Results showed a decrease in lar with age, with the highest risks observed in younger patients (18–19 years), especially for lung cancer (71 males and 124 females per 100,000 scans). Females generally exhibited higher lar than males. Average brain doses were 14.20 mgy, while effective doses ranged from 1.74 to 3.08 msv. Lung doses were higher in males (24.51 mgy) compared to females (10.81 mgy), while females received slightly higher doses for the stomach, colon, and liver. The ct dose index volumetric (ctdivol) and dose length product (dlp) varied significantly across scanner models, with ge and siemens (64-slice) scanners showing lower values compared to toshiba scanners. Jordanian drls were found to be higher than compared international studies, indicating the need for dose optimization.
- PublicationFabrication And Characterization Of Passivated Perovskite Solar Cell With Zinc Oxide Quantum Dots As Electron Transport Layer(2025-02)Mohammed, Ahlaam Taher Nomaan SaeedThis work is dedicated to fabricate low-temperature processed n-i-p lead halide perovskite solar cells using zno quantum dot (qd)-based film as electron transport layer (etl). The work is divided into three main parts as follows: the first part reports the growth of low temperature zno qd-based film and lead halide perovskite (ch3nh3pbi3) film as an efficient etl and photo-active layer, respectively. The zno qd-etl was prepared from solution-based zno qds having average particle size of 4.4 nm using solvothermal route, then spin coated over ito substrate at different thicknesses and treated at different temperatures. 60 nm-thick zno film dried at 100 oc showed better quality in terms of surface coverage, qd-preserved nature with average grain size of 5.13 nm, and outstanding photoelectric property due to its high surface-to-volume ratio, thus it was selected as low temperature etl. Separately, ch3nh3pbi3 perovskite films were grown at different temperatures using dimethylformamide (dmf) solvent and treated with different anti-solvents. The analysis showed that chlorobenzene (cb)-treated perovskite film grown at 100 oc revealed void-free surface morphology with good crystallinity and optical properties, thus it was chosen as an efficient visible light-absorber in the fabricated pscs. In the second part, cb-treated ch3nh3pbi3 film annealed at 100 oc was integrated over 60 nm-thick zno qd-etl for fabricating pscs without and with inserting al2o3 passivating layer (⁓10 nm) into zno qd-etl/ ch3nh3pbi3 interface.