Saudi Cultural Missions Theses & Dissertations
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Item Restricted An Evaluation of Machine Learning and Deep Learning for Time Series Forecasting(Saudi Digital Library, 2025-08) Gadhi, Adel; Shelton, PeirisThis thesis investigates the use of machine learning and hybrid models to forecast time series data such as climate patterns, oil prices, Australian beer production, and sunspot activity. It examines traditional models like ARIMA and GARCH, as well as machine learning methods such as SVR, LSTM, RF, and DT, which better capture non-linear and complex relationships. The study also evaluates hybrid models like ARIMA-ANN and GARMA-LSTM, which consistently demonstrate superior forecasting accuracy across various datasets. The GARMA-LSTM model, in particular, proves effective for long-term forecasting, especially with sunspot and beer production data. Finally, the thesis applies an advanced deep learning system, WGAN-GP, to financial and climate data, showing that modern methods can move beyond classical assumptions and better capture complex, high-order dynamics.17 0Item Restricted Optimization and Characterization of Phoenix dactylifera L. Extracts on Anti-oxidant, Anti-melanogenesis, and Anti-diabetic Potentials(Saudi Digital Library, 2023-11-15) Alshammari, Fanar Hamad; Sang-Han, LeeThe optimization of the extraction of various dates from Tunisia, Algeria, Egypt, and other locations and their polyphenolic content as well as antioxidant activities were described in the prior literature; however, no systematic statistical technique was applied [1,18,19]. Additionally, the majority of the optimization of the extraction process was performed solely using RSM methodology, but the illustrious scientists made no attempt to compare the efficacy of predictive modeling with alternative, more effective methods such as ANN. Furthermore, to the best of our knowledge, this is the first study to use heat extraction (HE) with RSM and ANN to enhance the polyphenolic components and antioxidant activity of ripe Ajwa Date Seed (ADS) extracts. The aim was to use the RSM Box Behnken Design (BBD) tool to investigate and optimize extraction parameters such as extraction temperature, time, and ethanol concentration to acquire the maximum polyphenolic content and antioxidant potentiality from ADS. We argue that the projected values generated by the RSM-BBD approach correspond to the actual results and that this statistical tool is an effective model to optimize ADS polyphenolic compound extraction and antioxidant activity. The estimating capabilities and modeling effectiveness of the RSM and ANN models were also statistically examined. Additionally, we have also profiled the secondary metabolites of ADS using high-resolution mass spectrometry analysis. About 15% of world population accounts for consuming whitening agents of skin in Asia along with increased interest about inner beauty products of skin whitening. Human skin, hair, and iris color are all determined by melanin, which is biosynthesized by three enzymes in human (74,80). Accumulation of melanin is dysregulated by melanogenesis process within the intracellular melanosomes presented in melanocytes [80]. Tyrosinase is a multifunctional enzyme taken part in production of melanin, which catalyzes the hydroxylation and subsequent oxidation of tyrosine, making it a crucial and rate-limiting processes of melanogenesis. It has been reported that tyrosinase-related protein 1 (TYP1) catalyzes the oxidation of 5,6-dihydroxy indole-2-carboxylicacid (DHICA), and hydroxylation of tyrosine to 3,4-dihydroxyphenylalnin (DOPA) (monophenolase) and the oxidation of DOPA to dopaquinone (diphenolase) in mice [76,80]. But this activity has been questioned in humans. Tyrosinase is structurally designed to store two copper ions in its active site for catalytic activity. Potentially chelating copper, extracts may limit tyrosinase activity in the skin, which would prevent melanogenesis. [81]. Tyrosinase-related protein 2 (TRP2) is a tautomerize. Melanosomes are the sites of activity for the three enzymes, all of which are metal-containing glycoproteins. Furthermore, melanocyte inducing transcription factor (MITF) is a DNA-binding transcription factor that regulates melanocyte proliferation, differentiation, and melanogenesis [78,79]. MITF is responsible for regulating the expression of these enzymes. Thus, the downregulation of melanogenesis-related proteins is one way to investigate the anti-whitening effect. In recent, there are no reports on potential regulation of melanogenesis of ADS. The purpose of present study was to confirm inhibitory effects of ADS on melanogenesis underlying mechanism.7 0Item Restricted Experimental and numerical investigation of air blast mitigation of single and multi-scale structures(Saudi Digital Library, 2023-10-30) Alshammari, Omar Ghareeb M; Rigby, Sam; Clarke, SamIn order to protect civilians and infrastructure against the damaging effects of explosions, understanding blast wave interactions with structures in complex environments is fundamental for effective blast mitigation development. Obstructing the direct propagation of blast waves towards targets using a small, porous structure formed as an array/matrix of smaller structural elements is usually a preferred protective strategy in urban environments due to issues related to sustainability including material use and public perceptions of hazard. The blast wave mitigation induced by interaction with obstacles in downstream region is primarily dominated by configuration- shapes and lengths of individual elements- of the obstacle itself. Whilst the blast wave mitigation behaviour of obstacles arranged as an array/matrix comprising single-length scale and regular shape is well known, the mitigation behaviour of obstacles arranged as fractals involving multi-scale length and self-similarity features is not clear yet. The primary aim of this thesis was to extensively understand the blast mitigation behaviour of fractal obstacles of increasing complexity for developing protection strategies and predictive methods. To achieve this, an experiment on blast wave interaction with fractal obstacles was conducted to measure the blast attenuation and observe the mitigation behaviour. CFD numerical models simulating air blast loading in free-field and complex interaction scenarios were validated against experimental data. Utilising the validated numerical models, the mitigation behaviour of blast loading through blast-obstacle interactions process was studied for single obstacle case, and fractal obstacles with increasing complexity scenarios. The experimental findings exhibited that obstacles with shapes closely resembling true fractals can induce local significant blast attenuation up to 26% in pressure and 16% in peak specific impulse attributed to a mechanism known as trapping. This indicated that the mechanism of blast mitigation of fractal obstacles of increasing complexity is fundamentally different from singular or arrays of regular obstacles. Furthermore, blast wave parameters behind different arrangements of fractal obstacles were found to be inherently determinable. The numerical simulations revealed that the development of a complex flow-field downstream is comprised of two zones: wave shadowing and wave interference in which mitigation patterns, specifically behind the single obstacle, can be predictable despite the complex interactions. It was also shown that increasing the fractal obstacles complexity can produce a better impedance and substantially alter the direction of the incident wave. This has demonstrated that the effectiveness of obstructing a blast wave, measured in terms of blast intensity mitigation, is classified according to the fractal complexity configuration from the lowest level to the highest level. The peak reduction in pressure and specific impulse in the downstream region of fractal obstacle with highest level of complexity was numerically found to be 60% and 40% respectively. Therefore, the finding of this can be utilised in structural design and optimization of protective structures with improved blast mitigation.8 0