Engineering Commons^™

A Three-Dimensional, Analytical Wind Turbine Wake Model: Flow Acceleration, Empirical Correlations, And Continuity, Zein Ahmad Sadek

Dissertations and Theses

A new, three-dimensional, analytical, steady state wake model is presented which includes local flow acceleration near the rotor improving wake description compared to existing models. Wake structures such as the momentum deficit and regions of accelerated flow are concisely described with compound and normal Gaussian functions. Large-eddy simulations (LES) are used as training data to develop the model using two, inline turbines under various inflow conditions parameterized by hub height wind speed and turbulence intensity. Mass conservation is considered by fixing two components of the wake velocity model and optimizing the third to best satisfy continuity; after which, the model …

Methodologies For Quantum Circuit And Algorithm Design At Low And High Levels, Edison Tsai

Dissertations and Theses

Although the concept of quantum computing has existed for decades, the technology needed to successfully implement a quantum computing system has not yet reached the level of sophistication, reliability, and scalability necessary for commercial viability until very recently. Significant progress on this front was made in the past few years, with IBM planning to create a 1000-qubit chip by the end of 2023, and Google already claiming to have achieved quantum supremacy. Other major industry players such as Intel and Microsoft have also invested significant amounts of resources into quantum computing research.

Any viable computing system requires both hardware and …

Augmentative And Alternative Communication Use, Service Delivery Experiences, And Communicative Participation For People With Amyotrophic Lateral Sclerosis, Betts Peters

Dissertations and Theses

People with amyotrophic lateral sclerosis (ALS) often experience changes to their speech, and may use augmentative and alternative communication (AAC) devices and techniques to maintain the ability to communicate. The use of AAC may facilitate the participation of people with ALS in various life situations involving communication. There is limited data in the literature about the AAC approaches currently used by people with ALS, the professional services they receive to support communication, or the effects of AAC on their communicative participation. This dissertation involved a nationwide online survey of people with ALS, and comprises three papers intended to add to …

Observation And Control Of Photoemission And Electric Field Enhancement Of Plasmonic Antennas Through Photoemission Electron Microscopy, Christopher M. Scheffler

Dissertations and Theses

Photoemission electron microscopy (PEEM) is an imaging method which uses electrons excited through the photoelectric effect to characterize a sample surface with nanometer-level resolution. In PEEM, a high intensity laser excites electrons from the surface of the material and electron optics are used to form an image from the intensity and spatial distribution of the photoemission from the sample. The goal of this research was to study and maximize light confinement, which was accomplished using plasmonic nanostructures. Surface plasmons represent oscillations in the electron density of a material and can occur along the transition interface between a metal and a …

Developing An Energy Service Interface Specification, Jaime T. Kolln

Dissertations and Theses

Developing an Energy Service Interface (ESI) specification requires engaging a community of stakeholders including grid operators, Information and Communication Technology implementors, integrators, and finally standards bodies who will define an interface that respects and boundaries of ownership and roles of responsibility in order to activate millions of Distributed Energy Resources for the provision of grid services. By applying Interoperability Maturity Model Criteria and ESI principles to common grid-DER service use cases, the Grid Modernization Lab Consortium team will engage subject matter experts to develop a specification, with an eventual goal of informing development of ESI compliant profiles or standards. The …

An Investigation Into Magnetic Gears And Magnetic Springs For Marine Hydrokinetic Power Generators, Hossein Baninajar

Dissertations and Theses

Marine hydrokinetic generators often use mechanical gears to convert the low-speed motion into the high-speed rotary motion that is required for conventional electrical generators. While mechanical gearboxes have a high torque density and can reach high efficiencies, they suffer from serious reliability issues. Recently, magnetic gearing technology has been proposed as a means of making hydrokinetic generators more reliable. As magnetic gears use magnetic field modulation to create speed change, they offer a high reliability, nonfriction, power transmission mechanism that limits the wear to only the bearings and makes the magnetic gears almost maintenance-free. During an over-torque condition, a magnetic …

Mass Capacity Analysis Of Stormwater Control Measures Using Synthetic Stormwater With Silica, Organic And Hydrocarbon Constituents, Craig Michael Fairbaugh

Dissertations and Theses

Stormwater control measure (SCM) performance is well studied regarding solids removal; however, analysis of mass loading capacity, long-term performance, and maintenance demands are challenging due to the variability and multiple constituents inherent in urban stormwater. This research examines the long-term water quality performance and sediment mass capacity of two common SCMs: high rate biofiltration (HRBF) and conventional bioretention (BRT). Pollutant removal trials were conducted in a laboratory setting per the New Jersey Department of Environmental Protection (NJDEP) filtration protocol in two phases: the first using inorganic sediment per the NJDEP protocol, the second phase with the addition of organic sediment …

Seismic Performance Design Criteria Of Existing Bridge Bent Plastic Hinge Region And Rapid Repair Measures Of Earthquake Damaged Bridges Considering Future Resilience, A K M Golam Murtuz

Dissertations and Theses

The main objective of this research was to evaluate the seismic performance of existing sub-standard reinforced concrete (RC) bridge column-spread footing subassemblies and to quantify the material strain limits through a full-scale experimental program. A total of six column-footing test specimens with pre-1990 construction details were subjected to reverse cyclic lateral loading, utilizing a conventional three-cycle symmetric loading protocol and a protocol representing the demands expected from a CSZ earthquake. Additionally, the tests were designed so that variable axial loading could be applied to simulate the secondary load effects experienced during an earthquake in a column that is part of …

Robust Design Methodologies Under Performance Variations For More Than Moore Technologies: Cnfets & 3dics, Satya Keerthi Vendra

Dissertations and Theses

Various emerging technologies have shown great potential of supplementing silicon transistors as Moore's law slows down. One such disruptive technology, Carbon Nanotube Field Effect Transistors (CNFET), among others, promises increased speed and integration with reduced power consumption. However, due to a limited controllability over the Carbon Nano-tube(CNT) growth process, CNFETs show large variations in their performance and behavior. It is therefore difficult to predict and model their behavior while design suggestions are also challenging. CNT variations are important for a realistic delay modelling. Due to the presence of CNT-specific variations, conventional CMOS evaluation techniques cannot be used for CNFETs.

This …

Efficient Capture Of Co2 And Its Selective Reduction To Formic Acid Using Tin-Based Nanomaterials, Emmanuel Oluwaseun Abdul

Dissertations and Theses

CO₂ emissions from the combustion of fossil fuels and other anthropogenic sources have become the main contributing factors to global warming. Chemical methods of absorbing/capturing CO₂ from combustion flue gases have made it a sought-after approach in engineering emission solutions because of its simplistic and convenient operation and high absorption efficiency. The conversion of CO₂ into renewable fuels and high energy density chemicals by clean and economic processes has drawn scientists' attention over the decades. The electrocatalytic conversion of CO₂ using Sn-based materials has been demonstrated to be a promising method for producing formate, an important …

The Impact Of New Light Rail Service On Employment Growth In Portland, Oregon, Lahar Santra

Dissertations and Theses

This study quantitatively examines the impact of the new Light Rail Transit (LRT) service on employment growth in retail, knowledge, and service sectors before and after opening the LRT. At the corridor level, this study conducts a case study of Greenline in Southeast Portland, Oregon. The results of the corridor level study suggest that the new LRT service increased employment along the Greenline corridor among all the three sectors of interest- retail, knowledge, service in the long-term (ten years) while having slightly different results for the short-term (five years), likely due to the slow growth of LRT benefits. This study …

Materials And Methodologies For Spectroscopic And Optical Analytical Applications In Cultural Heritage Conservation Science, Lyndsay Nichole Kissell

Dissertations and Theses

The field of conservation science falls in the intersection of science and art. The work of conservation scientists may include any single subdiscipline of chemistry, though it is most commonly a highly interdisciplinary field taking skills from analytical, organic, and inorganic chemistry, as well as surface and materials science. The aims of conservation scientists are to answer questions about the production and aging of material cultural heritage. Knowing the materials used by an artist can lead to insight about the intentions of the object and knowing how those materials degrade will enable the use of preventative measures to ensure the …

Random Lasing In Nano-Crystalline Zinc-Oxide Films, Benito Reynaldo Resendiz

Dissertations and Theses

In this thesis, we explore the preparation of random lasers (RLs) using solution-deposited, randomly packed nano-particle films of zinc oxide (ZnO) impregnated with silicon dioxide (SiO₂) nanospheres. RLs have their scatterers randomly oriented, while their lasing comes from light propagating along closed paths through the scattering environment. It is shown here that random lasing is readily observed in films made of submicron sized ZnO particles. Adding transparent SiO₂ nanospheres to the films, we show there is an effective improvement of the lasing that is observable in all of the samples spectra. Specifically, we found that the lasing …

Development Of A Testing Station For Grid-Interactive Smart Inverter Systems, Yudong Lan

Dissertations and Theses

As renewable energy penetration increases within the electrical power grid, flexible power is required to ensure reliability. Reliability can be jeopardized by the fluctuation and non-dispatch ability of renewable generators. This instability is caused by an imbalance between the amount of power produced and the amount of power consumed. Grid-enabled battery inverter systems are considered a solution to offset voltage and frequency fluctuations, which arise due to this power imbalance.

The objective of this work is to develop a system for testing grid-enabled inverters. These inverters use one or more communication standards to control their interactions with the grid. This …

The Distributed Trust Model Applied To The Energy Grid Of Things, Narmada Sonali Fernando

Dissertations and Theses

Electric power system operators can manage distribution system utilization and usage by coordinating end customer usage of distributed energy resources. The end customers in this regard are Service Provisioning Customers, who provide their energy resources to a Grid Service Provider, which in turn dispatches large aggregations of distributed energy resources to provide reliable service to the power system. The security of this system relies upon information protection mechanisms, as described in IEEE 2030.5. However, in addition to preventive security measures, a monitoring function is required to ensure trustworthiness.

Trust models are a method to detect and respond to both expected …

The Evaluation Of Performance Of Spindle Connector And Its Finite Element Analysis, Suhyun Lee

Dissertations and Theses

The rapid development of machining technology and reliable high-speed machining systems has led to a fast operation of machines. However, machining machines cannot still meet modern requirements in terms of the quality of parts, the machine components, and the life of the tools. The major components of the machining system are machine tools, the spindle interfaces (the contact between the spindle and the tool holder), and tools. The choice of the spindle connector is the main decision, as this defines the limitation of the metal cutting efficiency and considerably influences the deformation of the machine tool. Therefore, it is very …

The Effect Of Viscosity On The Puddle Dynamics In Low Gravity Environment, Taif Hamed Saleh Al Juboori

Dissertations and Theses

Enormous liquid puddles are observed to jump spontaneously from non-wetting substrates when exposed to the nearly step-reduction in body force common to drop tower test facilities. The phenomenon is similar to the second half of terrestrial drop bounce experiments except that (1) the initial static equilibrium configuration satisfies the static contact angle condition, (2) the initial height of the puddle is limited to the capillary height, and (3), for drop tower test durations on the order of seconds, puddle volumes can be over 10⁴ times larger in mass (volume). The passive puddle jump mechanism provides a no-moving-parts deployment method …

Determinant Factors Of Bicyclist Injury Severity At Signalized And Unsignalized Intersections, Apy Das

Dissertations and Theses

Bicycling is becoming increasingly popular in Oregon and the US in general due to its environment friendliness as well as health benefits. With Oregon's population projected to increase by more than 30% over the next 30 years, improving the safety of the transportation network for persons on bicycles is important. In Oregon, majority of the bicyclist crashes occur at intersections. This thesis seeks to identify the determinant factors that significantly impact bicyclist crash injury severity at intersections. A mixed logit framework that accounts for any unobserved heterogeneity in the data and allows the estimated parameters to randomly vary across observations …

Improving Bicycle Crossings At Unsignalized Intersections Through Pavement Markings: Analysis Of The City Of Portland Innovative Strategy, Frank Boateng Appiah

Dissertations and Theses

The increasing trend in the number of bicycle crashes in the U.S since 2009 has been a major challenge to safety. In 2019, a total of 36,096 people were killed on U.S roadways. A total of 846 (2.3%) of these fatalities were bicyclists and around 75% of the bicycle fatalities occur in urban areas and intersections are common locations of crashes. Many bicycle enhancements such as bike boxes, bicycle signals, curb extensions have been installed to improve safety at signalized intersections. The City of Portland OR experimented with an innovative treatment to improve bicycle crossings at unsignalized crossings. This treatment, …

Building A Biomechanical Model Of A Rat Forelimb, Joshua Nathaniel Eric Mak

Dissertations and Theses

This paper presents a biomechanical model of the rat forelimb to test theories of determining viscoelastic muscle parameters. Several biomechanical models of rat hindlimbs have been developed and have explored the effects of multi-muscle control during locomotion. The forelimb model uses two ball-and-socket joints to model clavicle and scapula movement. A third ball-and-socket joint is used at the shoulder and two hinge joints are used at the elbow and wrist. Scapula motion is further constrained by muscle and spring elements. Each forelimb has 11 degrees of freedom, and 23 Hill-type muscles. The model has been created in Animatlab, which includes …

Improved Predictive Modeling Techniques For Non-Linear Solder Material Behavior, Arman Millian Ahari

Dissertations and Theses

Accurate prediction of fatigue life of solder joints in electronic packaging applications becomes of critical importance as semiconductor device technology and manufacturing constraints grow in complexity. To gain visibility on IC device performance and reliability, thermo-mechanical simulation is performed based on a unified, viscoplastic material model, which is dependent on nine parameters.

In this study, an improved method of Anand parameter extraction, which involves curve-fitting non-linear experimental stress data, is proposed to improve the accuracy of numerical predictions for solder reliability. Theoretical equations for uni-axial stress-strain response and creep response are derived, then details on their relevance to experimental and …

Undrained Cyclic Loading Of Low Plasticity Silty Soils In The Pacific Northwest Using Laboratory And Field Cyclic Shear Testing, Angelica Melissa Preciado Reyes

Dissertations and Theses

The cyclic behavior of a fine-grained low plasticity silty soil (plasticity index of approximately 15) at a site in Portland, Oregon, is characterized using a field and laboratory cyclic shear test program. The field cyclic tests were performed using the NHERI@UTexas large mobile shakers T-Rex and Rattler. The laboratory tests were performed using resonant column torsional shear and cyclic direct simple shear devices. This testing program's results were used to evaluate the soil's potential to develop excess pore water pressure with cyclic shear strains ranging from 0.00001% to 3%. The laboratory cyclic test results are compared against field cyclic test …

The Return To Anisotropy Across A Jet In Crossflow, Gregory P. Sakradse

Dissertations and Theses

With data from experiments on a jet of air emitting from an orifice flush with the floor of a wind tunnel providing a transverse flow, analysis is conducted to extract information about the state of anisotropy in the Reynolds stress tensor. Inflow velocities are modulated across two distinct turbulence intensity regimes while holding jet exit conditions constant, providing an opportunity to isolate effects of both jet to crossflow velocity ratio, r and the effects of the turbulence carried by the crossflow. Anisotropy in the Reynolds stress tensor is examined through anisotropy invariant maps and evolution of the function F, …

Automated Statistical Structural Testing Techniques And Applications, Yang Shi

Dissertations and Theses

Statistical structural testing(SST) is an effective testing technique that produces random test inputs from probability distributions. SST shows superiority in fault-revealing power over random testing and deterministic approaches since it heritages the merits from both of them. SST ensures testing thoroughness by setting up a probability lower-bound criterion for each structural cover element and test inputs that exercise a structural cover element sampled from the probability distribution, ensuring testing randomness. Despite the advantages, SST is not a widely used approach in practice. There are two major limitations. First, to construct probability distributions, a tester must understand the underlying software's structure, …

Quantum Grover's Oracles With Symmetry Boolean Functions, Peng Gao

Dissertations and Theses

Quantum computing has become an important research field of computer science and engineering. Among many quantum algorithms, Grover's algorithm is one of the most famous ones. Designing an effective quantum oracle poses a challenging conundrum in circuit and system-level design for practical application realization of Grover's algorithm.

In this dissertation, we present a new method to build quantum oracles for Grover's algorithm to solve graph theory problems. We explore generalized Boolean symmetric functions with lattice diagrams to develop a low quantum cost and area efficient quantum oracle. We study two graph theory problems: cycle detection of undirected graphs and generalized …

An Analysis Of Capillary Flow In Finite Length Interior Corners, Samuel Shaw Mohler

Dissertations and Theses

We analyze the mathematical robustness of slow massively parallel interior corner flows in low gravity environments. An interior corner provides a preferential orientation in low gravity environments. This is a luxury usually only found on earth. It also provides a passive pumping mechanism due to geometry of a conduit. The driving force for this flow is a pressure difference due to local surface curvature gradients. An alternative reasoning is that due to the geometrical constraints the interior corner surface energy is unbounded below. This results in the liquid wicking into corners indefinitely. Interior corner flow's main quantity of interest is …

Kinematic Demands On Pile-Supported Wharves Due To Liquefaction-Induced Lateral Ground Deformations, Thomas John Torkelson Ii

Dissertations and Theses

Kinematic demands from lateral soil deformations can be a major cause of damage to maritime and highway transportation structures such as wharves, ports, and bridges. Data from five centrifuge tests on pile-supported wharves were used to evaluate the accuracy of Newmark Sliding Block Analysis in estimating the kinematic demands on piles. The piles in the centrifuge tests were subjected to varying degrees of liquefaction-induced lateral ground deformations. Pile-pinning effects were included in the analysis by incorporating the lateral pile resistance in the limit-equilibrium slope stability analysis. The results of the analysis have shown that the median Newmark displacements better estimated …

Using Quantitative Stereology On High Resolution Sem Images To Estimate Diatom Percentages, Ariadna Covarrubias Ornelas

Dissertations and Theses

Diatoms are single-celled organisms of various shapes and sizes typically found in aquatic environments. When diatoms die, the organic material decomposes, and the outer skeletons (i.e., frustules) settle and accumulate as sedimentary deposits. These soils, called diatomaceous soils, exhibit nontraditional behavior since the diatom particles are typically hollow skeletons composed of amorphous silica with intricately patterned and abrasive surfaces. Recent studies have shown that diatomaceous soils are challenging geomaterials since even a small percentage of diatom particles will notably affect engineering behavior. Furthermore, laboratory studies on diatomaceous soil mixtures have demonstrated that many engineering soil properties depend on the percentage …

Field Trials And Long-Term Monitoring Of Microbially-Induced Desaturation For The Treatment Of Liquefiable Silty Soils, Kayla Rae Sorenson

Dissertations and Theses

Earthquake liquefaction hazards in silty soils are a critical problem in Portland, Oregon, and other areas around the world. This is a particular problem for existing facilities founded on liquefiable soils, for which there exists no cost-effective liquefaction mitigation solution at the present time. It is essential from both a seismic safety and a seismic resilience perspective to be able to mitigate potentially liquefiable soils underneath existing structures, and to do so in a cost-effective manner. Recent studies suggest that liquefaction mitigation using microbially-induced desaturation (MID) may provide this capability.

The objective of MID is to reduce earthquake-induced excess pore …

Modeling Cyanotoxin Production, Fate And Transport In Surface Waterbodies, Bernadel Rose Hintz Garstecki

Dissertations and Theses

Cyanobacteria exist throughout the world and are frequently associated with forming toxic blooms. The toxins produced by cyanobacteria, cyanotoxins, are harmful to both humans and animals. Rising temperatures due to global climate change, increased nutrient loading, and other anthropogenic impacts on waterbodies are expected to increase the prevalence of cyanobacteria. It is vital that we protect our drinking water supplies and natural water resources. Modeling the production and movement of these toxins is an important step in limiting exposure to them and evaluating management strategies to mitigate their impact. Cyanotoxins are diverse and the conditions under which they are formed …