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Full-Text Articles in Engineering

Design And Implementation Of Silicon-Based Mems Resonators For Application In Ultra Stable High Frequency Oscillators, Sarah Shahraini Jan 2019

Design And Implementation Of Silicon-Based Mems Resonators For Application In Ultra Stable High Frequency Oscillators, Sarah Shahraini

Electronic Theses and Dissertations

The focus of this work is to design and implement resonators for ultra-stable high-frequency ( > 100MHz) silicon-based MEMS oscillators. Specifically, two novel types of resonators are introduced that push the performance of silicon-based MEMS resonators to new limits. Thin film Piezoelectric-on-Silicon (TPoS) resonators have been shown to be suitable for oscillator applications due to their combined high quality factor, coupling efficiency, power handling and doping-dependent temperature-frequency behavior. This thesis is an attempt to utilize the TPoS platform and optimize it for extremely stable high-frequency oscillator applications. To achieve the said objective, two main research venues are explored. Firstly, quality factor …


Hurricane Imaging Radiometer (Hirad) Tropical Rainfall Retrievals, Abdusalam Alasgah Jan 2019

Hurricane Imaging Radiometer (Hirad) Tropical Rainfall Retrievals, Abdusalam Alasgah

Electronic Theses and Dissertations

The Hurricane Imaging Radiometer (HIRAD) is an airborne passive microwave remote sensor, developed to measure wind speed and rain rate in hurricanes. This dissertation concerns the development of a signal processing algorithm to infer tropical rainfall from HIRAD radiance (brightness temperature, Tb) measurements. The basis of the rain rate retrieval algorithm is an improved forward microwave radiative transfer model (RTM) that incorporates the HIRAD multi-antenna-beam geometry, and uses semi-empirical coefficients derived from an airborne experiment that occurred in the Gulf of Mexico off Tampa Bay in 2013. During this flight, HIRAD observed a squall line of thunderstorms simultaneously with an …


An Assessment Of Biosorption Activated Media For The Removal Of Pollutants In Up-Flow Stormwater Treatment Systems, Andrew Hood Jan 2019

An Assessment Of Biosorption Activated Media For The Removal Of Pollutants In Up-Flow Stormwater Treatment Systems, Andrew Hood

Electronic Theses and Dissertations

Nitrogen and phosphorus are often the limiting nutrients for marine and freshwater systems respectively. Additionally, stormwater often contains elevated levels of pathogens which can pollute the receiving water body and impact reuse applications [1-4]. The reduction of limiting nutrients and pathogens is a common primary target for stormwater best management practices (BMPs) [5]. Traditional BMPs, such as retention/detention treatment ponds require large footprints and may not be practical in ultra-urban environments where above ground space is limited. Upflow filters utilizing biosorption activated media (BAM) that can be placed underground offer a small footprint alternative. Additionally, BAM upflow filters can be …


The Challenges And Barriers Facing Successful Lean Implementation In The Qatari Manufacturing Organizations, Abdulwahab Alyousef Jan 2019

The Challenges And Barriers Facing Successful Lean Implementation In The Qatari Manufacturing Organizations, Abdulwahab Alyousef

Electronic Theses and Dissertations

The success of Toyota, the inventor of Lean Systems has drawn the attention of academics, researchers, and executives in the last decades. However, existing lean research is largely focused on developed economies in Europe, the Americas, and in Southeast Asia with little focus on the Arab world in general and Qatar specifically. There has been an emergence of manufacturing organizations and Small and Medium- sized Enterprises (SME) in Qatar recently which was the focus of this research. Despite the many attempts to implement lean in organizations, there have been a large number of failed attempts. This research aims to study …


Stochastic Optimization And Applications With Endogenous Uncertainties Via Discrete Choice Models, Mengnan Chen Jan 2019

Stochastic Optimization And Applications With Endogenous Uncertainties Via Discrete Choice Models, Mengnan Chen

Electronic Theses and Dissertations

Stochastic optimization is an optimization method that solves stochastic problems for minimizing or maximizing an objective function when there is randomness in the optimization process. In this dissertation, various stochastic optimization problems from the areas of Manufacturing, Health care, and Information Cascade are investigated in networks systems. These stochastic optimization problems aim to make plan for using existing resources to improve production efficiency, customer satisfaction, and information influence within limitation. Since the strategies are made for future planning, there are environmental uncertainties in the network systems. Sometimes, the environment may be changed due to the action of the decision maker. …


A Study Of Perceptions On Incident Response Exercises, Information Sharing, Situational Awareness, And Incident Response Planning In Power Grid Utilities, Joseph Garmon Jan 2019

A Study Of Perceptions On Incident Response Exercises, Information Sharing, Situational Awareness, And Incident Response Planning In Power Grid Utilities, Joseph Garmon

Electronic Theses and Dissertations

The power grid is facing increasing risks from a cybersecurity attack. Attacks that shut off electricity in Ukraine have already occurred, and successful compromises of the power grid that did not shut off electricity to customers have been privately disclosed in North America. The objective of this study is to identify how perceptions of various factors emphasized in the electric sector affect incident response planning. Methods used include a survey of 229 power grid personnel and the use of partial least squares structural equation modeling to identify causal relationships. This study reveals the relationships between perceptions by personnel responsible for …


Multi-Level Optimization With Pricing Strategy Under Boundedly Rationality User Equilibrium, Guanxiang Yun Jan 2019

Multi-Level Optimization With Pricing Strategy Under Boundedly Rationality User Equilibrium, Guanxiang Yun

Electronic Theses and Dissertations

We study multi-level optimization problem on energy system, transportation system and information network. We use the concept of boundedly rational user equilibrium (BRUE) to predict the behaviour of users in systems. By using multi-level optimization method with BRUE, we can help to operate the system work in a more efficient way. Based on the introducing of model with BRUE constraints, it will lead to the uncertainty to the optimization model. We generate the robust optimization as the multi-level optimization model to consider for the pessimistic condition with uncertainty. This dissertation mainly includes four projects. Three of them use the pricing …


Factors Affecting Systems Engineering Rigor In Launch Vehicle Organizations, Denton Gibson Jan 2019

Factors Affecting Systems Engineering Rigor In Launch Vehicle Organizations, Denton Gibson

Electronic Theses and Dissertations

Systems engineering is a methodical multi-disciplinary approach to design, build, and operate complex systems. Launch vehicles are considered by many extremely complex systems that have greatly impacted where the systems engineering industry is today. Launch vehicles are used to transport payloads from the ground to a location in space. Satellites launched by launch vehicles can range from commercial communications to national security payloads. Satellite costs can range from a few million dollars to billions of dollars. Prior research suggests that lack of systems engineering rigor as one of the leading contributors to launch vehicle failures. A launch vehicle failure could …


Piezoresistive Behavior Of Carbon Nanopaper Polymer Composites For Strain Sensing, Jayden Beyrooti Jan 2019

Piezoresistive Behavior Of Carbon Nanopaper Polymer Composites For Strain Sensing, Jayden Beyrooti

Electronic Theses and Dissertations

Carbon nanopapers made of carbon nanotubes (CNTs) or carbon nanofibers (CNFs), possess unique electrical, thermal and mechanical properties and when integrated with a polymer matrix, can become a multifunctional composite capable of strain sensing and heat actuation. Smart structures such as these can be used in many applications including deployable space structures, human motion detection, and structural health monitoring as flexible, sensitive and stable strain sensors in addition to providing electrical heat actuation for the shape memory effect in polymers. This study focuses on strain sensing capabilities by developing a numerical model to predict piezoresistive behavior. The piezoresistive effect is …


Design, Development, And Testing Of A Miniature Fixture For Uniaxial Compression Of Ceramics Coupled With In-Situ Raman Spectrometer, Ryan Jordan Jan 2019

Design, Development, And Testing Of A Miniature Fixture For Uniaxial Compression Of Ceramics Coupled With In-Situ Raman Spectrometer, Ryan Jordan

Electronic Theses and Dissertations

This thesis is about the design, development and integration of an in-situ compression stage which interfaces through the Leica optical microscope coupled with a Renishaw InVia micro-Raman spectrometer. This combined compression stage and Raman system will enable structural characterization of ceramics and ceramic composites. The in-situ compression stage incorporates a 440C stainless steel structural components, 6061 aluminum frame, a NEMA 23 stepper motor. Two load screws that allow to apply compressive loads up to 14,137 N, with negligible off axis loading, achieving target stresses of 500 MPa for samples of up to 6.00 mm in diameter. The system will be …


Detection Of Ddh In Infants And Children Using Audible Acoustics, Tanvir Hassan Jan 2019

Detection Of Ddh In Infants And Children Using Audible Acoustics, Tanvir Hassan

Electronic Theses and Dissertations

Detection of developmental dysplasia of the hip (DDH) in infants and children is important as it leads to permanent hip instability. Current methods for detecting DDH, such as ultrasound and x-rays, are relatively expensive and need qualified medical personnel to administer the test. Furthermore, x-ray ionizing radiation can have potential harmful effects. In the current study, an acoustic non-invasive and simple approach was investigated for detection of DDH. Different benchtop simplified models and pig models were constructed and tested. Models were stimulated with band-limited white acoustic noise (10-2500 Hz) and the response of the models was measured. The power spectrum …


Mode Coupling In Space-Division Multiplexed Systems, Huiyuan Liu Jan 2019

Mode Coupling In Space-Division Multiplexed Systems, Huiyuan Liu

Electronic Theses and Dissertations

Even though fiber-optic communication systems have been engineered to nearly approach the Shannon capacity limit, they still cannot meet the exponentially-growing bandwidth demand of the Internet. Space-division multiplexing (SDM) has attracted considerable attention in recent years due to its potential to address this capacity crunch. In SDM, the transmission channels support more than one spatial mode, each of which can provide the same capacity as a single-mode fiber. To make SDM practical, crosstalk among modes must be effectively managed. This dissertation presents three techniques for crosstalk management for SDM. In some cases such as intra-datacenter interconnects, even though mode crosstalk …


A Multi-Species Single-Led Hazardous Gas Sensor For Commercial Space Applications, Akshita Parupalli Jan 2019

A Multi-Species Single-Led Hazardous Gas Sensor For Commercial Space Applications, Akshita Parupalli

Electronic Theses and Dissertations

In the interest of furthering both commercial and government-funded opportunities for deep space exploration, the safety of life and equipment onboard must be absolutely certain. In this regard, the presence of any hazardous gases or combustion events onboard space vehicles must be quickly characterized and detected. Several hazardous gases of interest have absorption features in the mid-infrared range and can be detected with an infrared light source, via the principles of absorption spectroscopy. A non-dispersive infrared (NDIR) sensor that follows these principles has been developed to utilize light-emitting diodes (LEDs) for gas detection and quantification. LEDs contain a particular advantage …


Nonlinear Control Synthesis For Facilitation Of Human-Robot Interaction, Zhangchi Ding Jan 2019

Nonlinear Control Synthesis For Facilitation Of Human-Robot Interaction, Zhangchi Ding

Electronic Theses and Dissertations

Human-robot interaction is an area of interest that is becoming increasingly important in robotics research. Nonlinear control design techniques allow researchers to guarantee stability, performance, as well as safety, especially in cases involving physical human-robot interaction (PHRI). In this dissertation, we will propose two different nonlinear controllers and detail the design of an assistive robotic system to facilitate human-robot interaction. In Chapter 2, to facilitate physical human-robot interaction, the problem of making a safe compliant contact between a human and an assistive robot is considered. Users with disabilities have a need to utilize their assistive robots for physical interaction during …


Design, Synthesis And Characterization Of Biomimetic, Bioinspired And Bio-Related Functional Polymers For Atmospheric Water Recovery, Abdullah Alqassar Jan 2019

Design, Synthesis And Characterization Of Biomimetic, Bioinspired And Bio-Related Functional Polymers For Atmospheric Water Recovery, Abdullah Alqassar

Electronic Theses and Dissertations

Atmospheric water recovery in changing environments has received wide attention in environmental science and engineering communities due to rapid population growth and frequent droughts. This study is focused on the design, synthesis, and characterization of biomimetic, bioinspired, and bio-related functional polymers (b3p) to help resolve the water supply issue especially in arid or semi-arid regions. It is aimed to develop unique synthetic methods to access well-defined polymers with the aid of nanomaterials and metal to produce next generation polymer materials for better atmospheric water recovery. The design of such new b3p is bioinspired by some skin materials of biological species …


Chemical Vapor Deposition Growth Of Large Area 2d Mos2 Layers: Layer Orientation Control, Heterostructure Integration, And Applications For Stretchable Sensors., Md. Ashraful Islam Jan 2019

Chemical Vapor Deposition Growth Of Large Area 2d Mos2 Layers: Layer Orientation Control, Heterostructure Integration, And Applications For Stretchable Sensors., Md. Ashraful Islam

Electronic Theses and Dissertations

Two-dimensional (2D)-layered MoS2 layers have exhibited a broad set of unusual and superior material properties unattainable in any traditional bulk materials, drawing significant research interests nowadays. For instance, they present excellent semiconducting properties accompanying high carrier mobility and large current ON/OFF ratio as well as extensive in-plane strain limit and thickness, projecting high suitably for emerging flexible and stretchable electronics. Such properties and applications strongly depend on the physical orientation and chemical composition of constituent 2D layers. 2D MoS2 layers chemically grown in two distinct orientations, e.g., horizontal alignment for electronics and optoelectronics, and vertical alignment for electrochemical and sensing …


Long-Term Carbon And Copper Impact On Nutrient Removal Via Green Sorption Media In Dynamic Linear Ditch Environments, Diana Ordonez Jan 2019

Long-Term Carbon And Copper Impact On Nutrient Removal Via Green Sorption Media In Dynamic Linear Ditch Environments, Diana Ordonez

Electronic Theses and Dissertations

Nutrient-laden stormwater runoff causes environmental and ecological impacts on receiving water bodies. Biosorption Activated Media (BAM) composed of the sand, tire crumb, and clay have been implemented in stormwater best management practices due to its ability to efficiently remove nutrients from stormwater runoff, such as in roadside linear ditches, via unique chemophysical and microbiological processes. In this study, a set of fixed-bed columns were set up to simulate some external forces in roadside linear ditches and examine how these external forces affect the performance of BAM. In our experiment, scenario 1 simulates the impact that animals such as tortoises, moles …


Design And Structural Analysis Of Morphing Wings, Nicholas Fernandez Jan 2019

Design And Structural Analysis Of Morphing Wings, Nicholas Fernandez

Electronic Theses and Dissertations

Many natural flyers and marine swimmers can morph their wings during a number of unsteady maneuverings. With such wing morphing they are able to control the unsteady aerodynamic forces. A number of man-made flyers, such as unmanned aerial vehicles and micro air vehicles, fly in comparable Reynolds number range, but they are yet to acquire similar morphing capabilities as natural flyers or swimmers. Moreover, the knowledge of fluid structural interaction (FSI) of such morphing wings is not well developed. Hence there is a need to investigate the FSI of morphing wings. In this thesis, a morphing wing was designed and …


Multiphase Flow Modeling Of Molten Metal Atomization At High Gas Pressure, Kalpana Hanthanan Arachchilage Jan 2019

Multiphase Flow Modeling Of Molten Metal Atomization At High Gas Pressure, Kalpana Hanthanan Arachchilage

Electronic Theses and Dissertations

The high-pressure gas atomization is well known as one of the best powder manufacturing processes due to its controllability over powder size distribution. However, with the continuous improvement of new alloys, optimizing the operating parameters to maximize the yield is costly and time-consuming. Therefore, it is essential to understand the high-pressure gas atomization process and the effects of different operational parameters on the powder size distribution. Two-phase numerical simulations are performed to capture the interfacial dynamic during the atomization process and to obtain the effects of gas pressure, melt flow rate, and thermophysical properties of atomizing gas and the molten …


Computational Fluid Dynamics Investigation Of A Novel Hybrid Comprehensive Stage Ii Operation For Single Ventricle Palliation, Marwan Hameed Jan 2019

Computational Fluid Dynamics Investigation Of A Novel Hybrid Comprehensive Stage Ii Operation For Single Ventricle Palliation, Marwan Hameed

Electronic Theses and Dissertations

Hypoplastic left heart syndrome (HLHS) is a type of heart defect where the left ventricle is underdeveloped or not developed, resulting in only a single functioning right ventricle. Approximately 7.5% of patients with congenital heart disease are born with a single ventricle (SV) which is accompanied by a spectrum of other malformations such as atrophied ascending aorta, atrial septal defects, and ventricular septal defects (VSD). The existing three-hybrid staged surgical approach serving as a palliative treatment for this anomaly entails multiple complications and achieves a survival rate of only 50%. To reduce the trauma associated with the second stage of …


Probing The Influence Of Cx43 And Glucose On Endothelial Biomechanics, Md Mydul Islam Jan 2019

Probing The Influence Of Cx43 And Glucose On Endothelial Biomechanics, Md Mydul Islam

Electronic Theses and Dissertations

Endothelial cells (ECs) form the innermost layer of all vasculature and constantly receive both biochemical and biomechanical signals, yielding a plethora of biomechanical responses. In response to various biochemical or biomechanical cues, ECs have been documented to generate biomechanical responses such as tractions and intercellular stresses between the cell and substrate and between adjacent cells in a confluent monolayer, respectively. Thus far, the ability of endothelial tight junctions and adherens junctions to transmit intercellular stresses has been actively investigated, but the role of gap junctions is currently unknown. In addition, there is no report of the independent influence of hyperglycemia …


Novel Solid State Lasers Based On Volume Bragg Gratings, Evan Hale Jan 2019

Novel Solid State Lasers Based On Volume Bragg Gratings, Evan Hale

Electronic Theses and Dissertations

Since their invention in 1960, lasers have revolutionized modern technology, and tremendous amounts of innovation and development has gone into advancing their properties and efficiencies. This dissertation reports on further innovations by presenting novel solid state laser systems based on the volume Bragg gratings (VBGs) and the newly developed holographic phase mask (HPMs) for brightness enhancement, dual wavelength operation, and mode conversion. First, a new optical element was created by pairing the HPM with two surface gratings creating an achromatic holographic phase mask. This new optical device successfully performed transverse mode conversion of multiple narrow line laser sources operating from …


Numerical Simulation Of Non-Premixed And Premixed Axial Stage Combustor At High Pressure, Tyler Worbington Jan 2019

Numerical Simulation Of Non-Premixed And Premixed Axial Stage Combustor At High Pressure, Tyler Worbington

Electronic Theses and Dissertations

Axial-staged combustors represent an important concept that can be applied to reduce NOx emissions throughout a gas turbine engine. There are four main CFD models presented in this study that describe a highly turbulent jet-in-crossflow (JIC) simulation of partially premixed and non-premixed jets with a constant chamber pressure of 5 atm absolute. The equivalence ratio of the partially premixed jet was held constant at rich conditions with a �������� of 4 while the main stage varied from ��1 and ��2 of 0.575 and 0.73 with an average headend temperature of 1415K and 1545K, respectively. Chemistry was reduced by tabulation of …


Reliability And Robustness Enhancement Of Cooperative Vehicular Systems: A Bayesian Machine Learning Perspective, Hossein Nourkhiz Mahjoub Jan 2019

Reliability And Robustness Enhancement Of Cooperative Vehicular Systems: A Bayesian Machine Learning Perspective, Hossein Nourkhiz Mahjoub

Electronic Theses and Dissertations

Autonomous vehicles are expected to greatly transform the transportation domain in the near future. Some even envision that the human drivers may be fully replaced by automated systems. It is plausible to assume that at least a significant part of the driving task will be done by automated systems in not a distant future. Although we are observing a rapid advance towards this goal, which gradually pushes the traditional human-based driving toward more advanced autonomy levels, the full autonomy concept still has a long way before being completely fulfilled and realized due to numerous technical and societal challenges. During this …


Context-Centric Affect Recognition From Paralinguistic Features Of Speech, Andreas Marpaung Jan 2019

Context-Centric Affect Recognition From Paralinguistic Features Of Speech, Andreas Marpaung

Electronic Theses and Dissertations

As the field of affect recognition has progressed, many researchers have shifted from having unimodal approaches to multimodal ones. In particular, the trends in paralinguistic speech affect recognition domain have been to integrate other modalities such as facial expression, body posture, gait, and linguistic speech. Our work focuses on integrating contextual knowledge into paralinguistic speech affect recognition. We hypothesize that a framework to recognize affect through paralinguistic features of speech can improve its performance by integrating relevant contextual knowledge. This dissertation describes our research to integrate contextual knowledge into the paralinguistic affect recognition process from acoustic features of speech. We …


Shock Tube Investigations Of Novel Combustion Environments Towards A Carbon-Neutral Future, Samuel Barak Jan 2019

Shock Tube Investigations Of Novel Combustion Environments Towards A Carbon-Neutral Future, Samuel Barak

Electronic Theses and Dissertations

Supercritical carbon dioxide (sCO2) cycles are being investigated for the future of power generation. These cycles will contribute to a carbon-neutral future to combat the effects of climate change. These direct-fired closed cycles will produce power without adding significant pollutants to the atmosphere. For these cycles to be efficient, they will need to operate at significantly higher pressures (e.g., 300 atm for Allam Cycle) than existing systems (typically less than 40 atm). There is limited knowledge on combustion at these pressures or at the high dilution of carbon dioxide. Nominal fuel choices for gas turbines include natural gas and syngas …


Cryogenic Performance Projections For Ultra-Small Oxide-Free Vertical-Cavity Surface-Emitting Lasers, Mina Bayat Jan 2019

Cryogenic Performance Projections For Ultra-Small Oxide-Free Vertical-Cavity Surface-Emitting Lasers, Mina Bayat

Electronic Theses and Dissertations

Small-sized vertical-cavity surface-emitting laser (VCSEL) may offer very low power consumption along with high reliability for cryogenic data transfer. Cryogenic data transfer has application in supercomputers and superconducting for efficient computing and also focal plane array cameras operating at 77 K, and at the lower temperature of 4 K for data extraction from superconducting circuits. A theoretical analysis is presented for 77 K and 4 K operation based on small cavity, oxide-free VCSEL sizes of 2 to 6 µm, that have been shown to operate efficiently at room temperature. Temperature dependent operation for optimally-designed VCSELs are studied by calculating the …


Design Of Unimorph Out-Of-Plane Piezoelectric Actuator, Kevin Chan Jan 2019

Design Of Unimorph Out-Of-Plane Piezoelectric Actuator, Kevin Chan

Electronic Theses and Dissertations

Electromechanical transduction is an important component of microelectromechanical systems (MEMS), a technology with wide-ranging applications, including mobile computing, sensors, energy harvesting, and displays. These disparate applications have varying performance requirements, but generally transduction efficiency, mechanical precision, response time, cost, compatibility with photolithography and other fabrication processes, and operability at micro-scale are all desired metrics for MEMS devices. Piezoelectric transduction provides substantial advantages, including precise displacements, quick response times, and high transduction efficiency. These strengths make piezoelectric transduction particularly well-suited for use in resonators, sensors, and energy harvesters. However, piezoelectric transduction also produces much smaller magnitudes of movements than other electromechanical …


On-Chip Esd Protection Design: Optimized Clamps, Linfeng He Jan 2019

On-Chip Esd Protection Design: Optimized Clamps, Linfeng He

Electronic Theses and Dissertations

The extensive use of Integrated Circuits (ICs) means complex working conditions for these tiny chips. To guarantee the ICs could work properly in various environments, some special protection strategies are required to improve the reliability of system. From all the possible reliability issues, the electrostatics discharge (ESD) might be the most common one. The peak current of electrostatics can be as high as tens of amperes and the peak voltage can be over thousand voltages. In contrast, the size of semiconductor device fabricated is continuing to scale down, making it even more vulnerable to high level overstress and current surge …


Disinfection By-Product Formation Potential Assessment For Central Florida Groundwater Supplies, Tulsi Shukla Jan 2019

Disinfection By-Product Formation Potential Assessment For Central Florida Groundwater Supplies, Tulsi Shukla

Electronic Theses and Dissertations

Disinfection of potable water supplies is a primary requirement of the United States' Environmental Protection Agency's (USEPA's) Safe Drinking Water Act. The use of chlorine as a disinfectant is widely accepted by water purveyors due to its effectiveness and low cost. However, chlorine reacts with natural organic matter present in water supplies to form suspected carcinogenic disinfection by-products (DBPs). In this work, the formation of the regulated chlorinated by-products total trihalomethanes (TTHMs) and haloacetic acids (HAA5) for eleven Central Florida wells has been investigated. Fluorescence, UV-254, dissolved organic carbon (DOC), specific UV absorbance (SUVA), chlorine decay, and TTHM and HAA5 …