2,073 Works

Poly Silicon on Oxide Contact Silicon Solar Cells

Jingxuan Kang
Silicon photovoltaic (PV) is a promising solution for energy shortage and environmental pollution. We are experiencing an era when PV is exponentially increasing. Global cumulative installation had reached 380 GW in 2017. Among which, silicon-based PV productions share more than 90% market. Performance of the first two-generation commercial popular silicon solar cells - Al-BSF and PERC - are limited by metal/Si contacts, where interface defects significantly reduce the open-circuit voltage. In this context, full-area passivation...

Investigating Semiconductor Nanostructures Functionalized by Emerging Materials for Optoelectronic Devices

Norah M. Alwadai
Wide and direct bandgap semiconductors (WBSs) are promising materials for many deep UV (DUV) applications. However, several challenges presently hinder the enhancement of DUV optoelectronics, such as low crystal quality, as well as complex and costly fabrication and growth processes that prevent production of high-performance devices, especially for large-scale applications. As a part of the study reported in this dissertation, I demonstrate several novel WBS-based devices with improved or novel functionalities, for the first time....

Seawater-induced Biofouling in Direct Contact Membrane Distillation

Sarah A. Alsaidalani
Membrane distillation (MD) is a promising desalination technology which allows to achieve high salt rejection at low energy expenses as compared to conventional desalination processes. However, just like in any other membrane separation process, the MD membrane is susceptible to biofouling which is one of the critical problems in membrane-based systems. In this study, we investigated the effects of spacer design and feed temperature on the biofilm formation and proliferation in a flat-sheet direct contact...

Comparison of avirulent pathogen Pseudomonas syringae and beneficial Enterobacter sp SA187 for enhancing salt stress tolerance in Arabidopsis thaliana

Rewaa S. Jalal
Abiotic stresses such as salt stress are the major limiting factors for agricultural productivity, and cause global food insecurity. It is well known that plant associated beneficial microorganisms can stimulate plant growth and enhance resistance to abiotic stresses. In this context, bacterial endophytes are a group of bacteria that colonize the host plant and play a fundamental role in plant growth enhancement under stress condition. Recently, our group reported that the beneficial bacteria Enterobacter sp.SA187...

Photophysics of Organic Molecular Systems – A Study of Excited State Dynamics

Ahmed Balawi
This thesis is dedicated to studies of the excited-state dynamics in organic molecular systems for solar energy conversion by employing time-resolved experimental techniques. Organic photovoltaic (OPV) devices have received significant attention in the past decade and reaching record high power conversion efficiencies (PCE) above 17%. An essential step towards reaching the predicted PCE limit of 25.5% is to develop a comprehensive picture of the photophysical processes, specifically the loss processes, in OPV devices. It is...

Double Compression Expansion Engine: Evaluation of Thermodynamic Cycle and Combustion Concepts

Vijai Shankar
The efficiency of an internal combustion (IC) engine is governed by the thermodynamic cycle underpinning its operation. The thermodynamic efficiency of these devices is primarily determined by the temperature gradient created during the compression process. The final conversion efficiency also known as brake thermal efficiency (BTE) of IC engines, however, also depend on other processes associated with its operation. BTE is a product of the combustion, thermodynamic, gas-exchange, and mechanical efficiencies. The improvement of BTE...

Photosynthetic Oxygenation and Nutrient Utilization by Chlorella vulgaris in a Hybrid Membrane Bioreactor and Algal Membrane Photobioreactor System

Yasmeen Hani Kamal Najm
Aerobic activated sludge membrane bioreactors (AS-MBR) in municipal wastewater treatment are compact systems that can efficiently perform biological organic oxidation. However, aerobic processes require mechanical aeration accounting for over 40% of total expenditure of a wastewater facility. Additionally, a global urgency for nutrient (Nitrogen/Phosphorus) removal strategies due to surges of eutrophication events requires complex MBR configurations. An innovative and cost-effective process was developed with a dual income-stream: high-quality treated effluent and value-added microalgal biomass for...

GPS Observations and Modelling of Crustal Deformation in Gulf of Aqaba

Nicolas Castro-Perdomo
The Dead Sea Transform fault (DST) is one of the most prominent tectonic features in the eastern Mediterranean region, located between the Arabian plate and the Sinai sub-plate. Several aspects of this fault system have been thoroughly studied. However, its present-day kinematics along its southern end in Gulf of Aqaba remains poorly understood. This dissertation focusses on crustal motions near Gulf of Aqaba by using geodetic observations and analytical models of crustal deformation. Here we...

Mechanism Triggering Pre-Ignition Events and Ideas to Avoid and Suppress Pre-Ignition in Turbocharged Spark-Ignited Engines

Eshan Singh
Turbocharged spark-ignited engines may encounter stochastic events of premature ignition of the fuel-air mixture, termed as pre-ignition. Pre-ignition often leads to extremely high peak pressure and pressure oscillations, causing engine damage. A review of pre-ignition in historic times is done in this dissertation, and the similarities and differences compared to modern pre-ignition issue are brought forth. Experiments conducted with varying injection strategies yielded varying pre-ignition tendency. The pre-ignition tendency correlated with the charge cooling tendency...

Atomic Force Microscopy Characterization of Nanocontacted III nitride Nanostructures

Latifah Almaghrabi
A conductive atomic force microscopy (c-AFM) investigation of GaN nanostructures is reported for strain engineering optoelectronic and piezotronic devices. The use of AFM enables the simultaneous correlation between the surface morphology and charge carrier transport through the nanostructures. The samples under investigation are molecular beam epitaxy (MBE) grown InGaN/GaN nanowires on Ti coated Mo substrate and GaN nanowires on ITO. The metal-semiconductor interface between the metallic substrates and the GaN nanostructures form the bottom contact....

Interfacially Polymerized Thin-Film Composite Membranes Based on Biophenolic Material for Liquid Separation

Banan O. Alhazmi
Abstract: The aim of this research is to fabricate thin-film composite (TFC) membranes using a synthetic derivative of plant-based phenols, as a non-toxic building block for interfacial polymerization. Classical interfacially polymerized composite membranes are heavily integrated in reverse osmosis and nanofiltration applications for water and wastewater treatment and most recently for chemical and pharmaceutical industries. Implementing sustainable practices in membrane fabrication by exploiting greener alternatives to conventional chemicals can directly reduce hazardous waste and ultimately...

Planetary Health for the Arabian Peninsula: The Environmental Limits of Human Population.

Philip M. Mitchell
Human society can be thought of as a heat engine that is powered by fossil fuel and sunlight. The free energy that fossil fuels provide has enabled the development of our modern global human civilization and has artificially raised the human carrying capacity of the planet. Here, I discuss the roots of human population theory in the context of environmental limits, and argue that examining this issue is an essential matter of public health. The...

Highly Fluorinated Macrocycles and Macrocycle-Based Polymers and Their Prospective Applications in Energy-Intensive Separations

Abdulmajeed W. Hashem
The fluorination of porous materials often leads to the enhancement of properties such as stability, crystallinity and selective adsorption. Although there has been much interest in the fluorination of many types of porous materials, little research has been done on the fluorination of macrocycles, specifically trianglimine and leaning pillararene based materials. In this work, we introduce for the first time highly fluorinated trianglimine and leaning pillararene and show the enhancement effects brought about by the...

New Algorithms to Solve the Positioning Problem of Outdoor Localization Using Constrained and Unconstrained Optimization Techniques

Muhanned Alsaif
The demand for outdoor precise location is increasing with the development of new applications such as autonomous vehicles, exploration robots and wireless sensor networks. Global Navigation Satellite System (GNSS) is the go-to system for outdoor localization. This thesis focuses on developing new methods for GNSS single-point positioning (SPP) model, where no access to a reference station or precise GNSS parameters is needed. We investigated the limitations of the standard method, least- squares adjustment (LSA), and...

Investigation of OH + Fuel Elementary Reactions

Dapeng Liu
Increasingly stringent legislations call for more efficient and cleaner combustion technology as well as sustainable fuels. Chemical kinetic models are required in designing and optimizing novel engine concepts as well as selecting appropriate renewable fuels. Among the many reactions controlling fuel reactivity, OH + Fuel elementary reaction is one of the most important reactions that plays a critical role from low to high temperatures. In this thesis, OH + Fuel elementary reactions are studied for...

Applications of Magnetic Transition Metal Dichalcogenide Monolayers to the Field of Spin-­orbitronics

Idris Smaili
Magnetic random­access memory (MRAM) devices have been widely studied since the 1960s. During this time, the size of spintronic devices has continued to decrease. Conse quently, there is now an urgent need for new low­dimensional magnetic materials to mimic the traditional structures of spintronics at the nanoscale. We also require new effective mechanisms to conduct the main functions of memory devices, which are: reading, writ ing, and storing data. To date, most research efforts have...

Renewable Aromatics from the Degradation of Polystyrene under Mild Conditions

Nouf M. Al Jabri
Polystyrene (PS) is one of the most important polymers in the plastic sector due to its inexpensive cost as well as many preferred properties. Its international market is expected to achieve $28.2 billion by 2019. Although PS has a high calorific value of 87 GJ tonne-1, there is no a practical method to manage its waste but landfill. As a result, the PS debris in the oceans has reached 70% of the total plastic debris....

Thermal Limits and Thresholds of Red Sea Biota

Veronica Chaidez
As ocean temperatures continue to rise, the effect of temperature on marine organisms becomes highly relevant. The Red Sea is the warmest sea and is rapidly warming with current surface temperatures (28 – 34 °C) already exceeding those of most tropical systems. This has major consequences for organisms that may already find themselves at their thermal limits. The aim of this project was to define the thermal limits and thresholds of certain Red Sea species....

Exploiting Data Sparsity In Covariance Matrix Computations on Heterogeneous Systems

Ali Charara
Covariance matrices are ubiquitous in computational sciences, typically describing the correlation of elements of large multivariate spatial data sets. For example, covari- ance matrices are employed in climate/weather modeling for the maximum likelihood estimation to improve prediction, as well as in computational ground-based astronomy to enhance the observed image quality by filtering out noise produced by the adap- tive optics instruments and atmospheric turbulence. The structure of these covariance matrices is dense, symmetric, positive-definite, and...

Genome-scale Evaluation of the Biotechnological Potential of Red Sea Bacilli Strains

Ghofran K. Othoum
The increasing spectrum of multidrug-resistant bacteria has caused a major global public health concern, necessitating the discovery of novel antimicrobial agents. Additionally, recent advancements in the use of microbial cells for the scalable production of industrial enzymes has encouraged the screening of new environments for efficient microbial cell factories. The unique ecological niche of the Red Sea points to the promising metabolic and biosynthetic potential of its microbial system. Here, ten sequenced Bacilli strains, that...

Versatile High-Performance Regenerated Cellulose Membranes Prepared using Trimethylsilyl Cellulose as a Precursor

Tiara Puspasari
Cellulose has emerged as an indispensable membrane material due to its abundant availability, low cost, fascinating physiochemical properties and environment benignancy. However, it is believed that the potential of this polymer is not fully explored yet due to its insolubility in the common organic solvents, encouraging the use of derivatization-regeneration method as a viable alternative to the direct dissolution in exotic or reactive solvents. In this work, we use trimethylsilyl cellulose (TMSC), a highly soluble...

Stimuli Responsive Self-Assembled Hybrid Organic-Inorganic Materials

Safaa Al-Rehili
Because of the latest developments in nanotechnology and the need to have new functions, a high demand for innovative materials is created. The technological requirements for new applications cannot be fulfilled by most of the well-developed materials like metals, plastics, or ceramics. Therefore, composite materials that can exhibit better properties in contrast to their single counterpart represents a valuable and interesting alternative for the development of new and more performing functional materials. In the past...

The Role of Chromatin Associated Proteins in Plant Innate Immunity and Jasmonic Acid Signaling

Mai Jarad
Pathogen-associated molecular pattern (PAMP) recognition occurs by plasma membrane located receptors that induce among other processes nuclear gene expression. The plant FLS2-BAK1 receptor complex binds the bacterial PAMP, flg22 and induces a series of defense responses. The resulting signal transduction events occur through the activation of two MAPK signaling cascades, which trigger a rapid and strong activation of MPK3, MPK4 and MPK6. Cellular responses to pathogens are regulated by the activated MAPKs, which lead to...

A Finite Difference, Semi-implicit, Equation-of-State Efficient Algorithm for the Compositional Flow Modeling in the Subsurface: Numerical Examples

Sebastian Saavedra
The mathematical model that has been recognized to have the more accurate approximation to the physical laws govern subsurface hydrocarbon flow in reservoirs is the Compositional Model. The features of this model are adequate to describe not only the performance of a multiphase system but also to represent the transport of chemical species in a porous medium. Its importance relies not only on its current relevance to simulate petroleum extraction processes, such as, Primary, Secondary,...

Performance Analysis of High-Order Numerical Methods for Time-Dependent Acoustic Field Modeling

Pedro Henrique Rocha Moy
The discretization of time-dependent wave propagation is plagued with dispersion in which the wavefield is perceived to travel with an erroneous velocity. To remediate the problem, simulations are run on dense and computationally expensive grids yielding plausible approximate solutions. This work introduces an error analysis tool which can be used to obtain optimal simulation parameters that account for mesh size, orders of spatial and temporal discretizations, angles of propagation, temporal stability conditions (usually referred to...

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