Digital Commons Network^™

Towards A Fluid Solid Interaction Model Of A Dynamic Lung, Justin C. Jacobs

Electronic Theses and Dissertations

Because the pulmonary system is a site for both environmental particulate contamination, as well as drug delivery into the body, numerous research groups have focused on precisely understanding its inner-workings. Past research has demonstrated the need to realistically model the lung walls in order to accurately capture the complex airflow profile throughout all of the branches. Since this is paramount to properly replicating particulate transport in the lung, computational fluid dynamics simulations on their own are inadequate, as they cannot account for lung wall dilation. Only by coupling the fluid and solid domains can natural lung behavior can be effectively …

Thermally Actuated Resonant Silicon Crystal Nanobalances, Arash Hajjam

Electronic Theses and Dissertations

As the potential emerging technology for next generation integrated resonant sensors and frequency references as well as electronic filters, micro-electro-mechanical resonators have attracted a lot of attention over the past decade. As a result, a wide variety of high frequency micro/nanoscale electromechanical resonators have recently been presented. MEMS resonators, as low-cost highly integrated and ultra-sensitive mass sensors, can potentially provide new opportunities and unprecedented capabilities in the area of mass sensing. Such devices can provide orders of magnitude higher mass sensitivity and resolution compared to Film Bulk Acoustic resonators (FBAR) or the conventional quartz and Surface Acoustic Wave (SAW) resonators …

Peak-To-Average-Power-Ratio (Papr) Reduction Techniques For Orthogonal-Frequency-Division- Multiplexing (Ofdm) Transmission, Bader Hamad Alhassoun

Electronic Theses and Dissertations

Wireless communication has experienced an incredible growth in the last decade. Two decades ago,the number of mobile subscribers was less than 1% of the world's population. As of 2011, the number of mobile subscribers has increased tremendously to 79.86% of the world's population.

Robust and high-rate data transmission in mobile environments faces severe problems due to the time-variant channel conditions, multipath fading and shadow fading. Fading is the main limitation on wireless communication channels. Frequency selective interference and fading, such as multipath fading, is a bandwidth bottleneck in the "last mile" which runs from the access point to the user. …

Photoelectrochemical Water Splitting For Hydrogen Production With Metal Oxide (Hematite And Cupric Oxide) Based Photocatalysts, Houwen Tang

Electronic Theses and Dissertations

Solar hydrogen is one ideal energy source to replace fossil fuel, as it is sustainable and environmentally friendly. Solar hydrogen can be generated in a number of ways. Photoelectrochemical (PEC) water splitting is one of the most promising methods for solar-to-chemical energy conversion. In this research project, metal oxide-based photocatalysts, especially hematite (fÑ-Fe2O3) and cupric oxide (CuO), were investigated for use as electrodes in PEC water splitting for solar hydrogen production.

In our research project of hematite-based electrodes, we started with the incorporation of transition metal, particularly titanium (Ti), in hematite thin films to modify the valence and …

New Open Source Software For Building Molecular Dynamics Systems, Bruce Michael Allen

Electronic Theses and Dissertations

The context of this work is the development of open source software to support researchers to quickly build systems of molecules for molecular dynamics (MD) simulations. The goal is achieved through the integration of three open source programs by judicious modifications and creation of new source code, which allows the creation of molecular models, MD cells and the LAMMPS geometry input files. The software changes work together supporting an easy and intuitive process for simulation system creation. Creation of multiple MD cells for research simulations becomes quicker and provides needed standardization to the simulation process. The researcher can select from …

Performance Study Of Ofdm Over Fading Channels For Wireless Communications, Ahmed Alshammari

Electronic Theses and Dissertations

Orthogonal Frequency Division Multiplexing (OFDM) is a very efficient multicarrier technique. OFDM is used more and more in recent wideband digital communications. It has numerous advantages such as the ability to handle severe channel conditions, efficient spectral usage, reduced inter symbol interference (ISI), and high data rate. Therefore, it has been utilized in many wired and wireless communication systems like DSL, wireless networks and 4G mobile communications.

Studying the performance of OFDM over different channels is the main focus of this research. Channels' environments simulated in Matlab are additive white Gaussian noise (AWGN) and fading channels. Each channel affects the …

Computationally Efficient Finite Element Models Of The Lumbar Spine For The Evaluation Of Spine Mechanics And Device Performance, Sean D. Smith

Electronic Theses and Dissertations

Finite Element models of the lumbar spine are commonly used for the study of spine mechanics and device performance, but have limited usefulness in some applications such as clinical and design phase assessments due to long analysis times. In this study a computationally efficient L4-L5 FSU model and a L1-Sacrum multi-segment model were developed and validated. The FSU is a functional spine unit consisting of two adjacent vertebral bodies, in this case L4 and L5. The multi-segment model consists of all lumbar vertebrae and the sacrum. The models are able to accurately predict spine kinematics with significantly reduced analysis times, …

Plug-In Hybrid Electric Vehicle In Smart Grid, Yin Yao

Electronic Theses and Dissertations

In this thesis, in order to investigate the impact of charging load from plug-in hybrid electric vehicles (PHEVs), a stochastic model is developed in Matlab. In this model, two main types of PHEVs are defined: public transportation vehicles and private vehicles. Different charging time schedule, charging speed and battery capacity are considered for each type of vehicles. The simulation results reveal that there will be two load peaks (at noon and in evening) when the penetration level of PHEVs increases continuously to 30% in 2030. Therefore, optimization tool is utilized to shift load peaks. This optimization process is based on …

Explicit Finite Element Modeling Of The Human Lumbar Spine, Milind Rao

Electronic Theses and Dissertations

Validated finite element (FE) models of the functional spinal unit (FSU) and lumbar spine are essential in design-phase device development and in assessing the mechanics associated with normal spine function and degenerative disc disease (DDD), as well as the impact of fusion and total disc replacement (TDR). Although experimental data from fully intact specimens can be used for model calibration and validation, the contributions from the individual structures (disc, facets, and ligaments) may be inappropriately distributed. Hence, creation of decompression conditions or device implantations that require structure removal may not have the proper resulting mechanics. An explicit FE formulation may …

Feature-Based Neuro-Symbolic Networks For Global Diagnostics, Tracy Lynn Schantz

Electronic Theses and Dissertations

Engineered system diagnostics have been researched over the years with many successful results. From transportation systems to office technologies, many have been equipped with self-diagnostic capabilities and are called Smart Machines. In spite of these advances, current diagnostic systems are driven by direct sensory information without much concern for patterns of the system behavior or features associated with them. For large-scale systems with complex dynamics, global as well as local diagnostics become of great importance, where sensory information is used as input for the local diagnostics, and patterns of behavior or features are utilized for global diagnostics.

The main objective …

The Bit Error Rate (Ber) Performance In Multi-Carrier (Ofdm) And Single-Carrier, Saleh M. Albdran

Electronic Theses and Dissertations

The spectacular growth of wireless communication tools has escalated the number of mobile subscribers from almost 700 million in 2000 to more than 4 billion in 2009. The huge number of subscribers has led to several issues with how service is provided. The high user demand has forced developers to overcome the problems of the old analog systems and to introduce OFDM as a promising technique that can fulfill users' high demands. This technique matches well with high data rate connection and provides a higher capacity for the subscribers' usage.

The OFDM, as a multi-carrier, is more complex than the …

Solar Photovoltaic System Modeling And Control, Qing Xia

Electronic Theses and Dissertations

To realize the benefits of grid-connected photovoltaic system, it is extremely important to reduce energy losses and improve reliability of grid-connected PV systems with high PV penetration. In this thesis, three different Maximum Power Point Tracking (MPPT) strategies named as Perturbation & Observation MPPT, Incremental Conductance MPPT and Fuzzy Logic Control MPPT have been analyzed, simulated and compared with each other to improve the efficiency of power conversion. A general discussion to counteract partial shading effect in several aspects is also provided in this thesis. In order to improve reliability of the system, an optimum current control loop with suitable …

Micro Channel Cooler Performance Improvement By Insonation, Peter Webb Higgins

Electronic Theses and Dissertations

The motivation for this work is the need to remove waste heat from laser diodes and high speed transistors in processes which are exponentially increasing past 1 kW/cm2 as anticipated by Moore's Law. The hypothesis guiding the work is that ultrasonic insonation of micro coolers employed to dissipate these heat loads can improve heat removal. It is thought that the mechanism promoting the benefit is enhancement of the ability of the coolant to remove latent heat in two-phase operation by managing entrained bubble size near the cooler's exit so as to forestall flow reduction or blockage caused by large bubbles, …