Engineering Commons^™

Formal Modeling And Verification Of Delay-Insensitive Circuits, Hoon Park

Dissertations and Theses

Einstein's relativity theory tells us that the notion of simultaneity can only be approximated for events distributed over space. As a result, the use of asynchronous techniques is unavoidable in systems larger than a certain physical size. Traditional design techniques that use global clocks face this barrier of scale already within the space of a modern microprocessor chip. The most common response by the chip industry for overcoming this barrier is to use Globally Asynchronous Locally Synchronous (GALS) design techniques. The circuits investigated in this thesis can be viewed as examples of GALS design. To make such designs trustworthy it …

Analysis Of Capillary Flow In Interior Corners : Perturbed Power Law Similarity Solutions, Joshua Thomas Mccraney

Dissertations and Theses

The design of fluid management systems requires accurate models for fluid transport. In the low gravity environment of space, gravity no longer dominates fluid displacement; instead capillary forces often govern flow. This thesis considers the redistribution of fluid along an interior corner. Following a rapid reduction of gravity, fluid advances along the corner measured by the column length z = L(t), which is governed by a nonlinear partial differential equation with dynamical boundary conditions. Three flow types are examined: capillary rise, spreading drop, and tapered corner. The spreading drop regime is shown to exhibit column length growth L ~ …

Advances In Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation By Processing Of Marine Ambient Noise, Lanfranco Muzi

Dissertations and Theses

Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction, and requires, particularly in shallow water environments, characterizing the bottom reflection loss with a precision that databank-based modeling cannot achieve. Recent advances in the technology of autonomous underwater vehicles (AUV) make it possible to envision a survey system for seabed characterization composed of a short array mounted on a small AUV. The bottom power reflection coefficient (and the related reflection loss) can be estimated passively by beamforming the naturally occurring marine ambient-noise acoustic field recorded by a vertical line array of hydrophones. However, the reduced array …

A Combined Energy And Geoengineering Optimization Model (Ceagom) For Climate Policy Analysis, John George Anasis

Dissertations and Theses

One of the greatest challenges that will face humanity in the 21^st century is the issue of climate change brought about by emissions of greenhouse gases. Energy use is one of the primary sources of greenhouse gas emissions. However, it is also one of the most important contributors to improved human welfare over the past two centuries and will continue to be so for years to come. This quandary has led a number of researchers to suggest that geoengineering may be required in order to allow for continued use of fossil fuels while at the same time mitigating the …

Transport Of Heat Activated Persulfate And Its Application For In-Situ Chemical Oxidation Of Residual Trichloroethylene, Lauren Dekker Quig

Dissertations and Theses

In situ chemical oxidation is a promising technology for the remediation of persistent subsurface contamination. Increasingly, the persulfate ion is being studied for use in these systems, both on its own as a strong oxidant and as the precursor to the even more reactive sulfate radical. Persulfate has been shown to treat a wide range of contaminants, from traditional Superfund contaminants such as chlorinated solvents to emerging pharmaceutical contaminants. Additionally, persulfate ISCO can be tailored to site and pollutant specific characteristics based on the method of persulfate activation (e.g., energy and catalysis activation) to the sulfate radical. Thermal activation of …

An Exploration Of Bicyclist Comfort Levels Utilizing Crowdsourced Data, Bryan Philip Blanc

Dissertations and Theses

Bicycle transportation has become a central priority of urban areas invested in improving sustainability, livability, and public health outcomes. Transportation agencies are striving to increase the comfort of their bicycle networks to improve the experience of existing cyclists and to attract new cyclists. The Oregon Department of Transportation sponsored the development of ORcycle, a smartphone application designed to collect cyclist travel, comfort, and safety information throughout Oregon. The sample resulting from the initial deployment of the application between November 2014 and March 2015 is described and analyzed within this thesis. 616 bicycle trips from 148 unique users were geo-matched to …

Photoluminescent Silicon Nanoparticles: Fluorescent Cellular Imaging Applications And Photoluminescence (Pl) Behavior Study, Sheng-Kuei Chiu

Dissertations and Theses

Molecular fluorophores and semiconductor quantum dots (QDs) have been used as cellular imaging agents for biomedical research, but each class has challenges associated with their use, including poor photostability or toxicity. Silicon is a semiconductor material that is inexpensive and relatively environmental benign in comparison to heavy metal-containing quantum dots. Thus, red-emitting silicon nanoparticles (Si NPs) are desirable to prepare for cellular imaging application to be used in place of more toxic QDs. However, Si NPs currently suffer poorly understood photoinstability, and furthermore, the origin of the PL remains under debate.

This dissertation first describes the use of diatomaceous earth …

Evaluation Of Data-Path Topologies For Self-Timed Conditional Statements, Navaneeth Prasannakumar Jamadagni

Dissertations and Theses

This research presents a methodology to evaluate data path topologies that implement a conditional statement for an average-case performance that is better than the worst-case performance. A conditional statement executes one of many alternatives depending on how Boolean conditions evaluate to true or false. Alternatives with simple computations take less time to execute. The self-timed designs can exploit the faster executing alternatives and provide an average-case behavior, where the average depends on the frequency of simple and complex computations, and the difference in the completion times of simple and complex computations. The frequency of simple and complex computations depends on …

Network Structure, Network Flows And The Phenomenon Of Influence In Online Social Networks: An Exploratory Empirical Study Of Twitter Conversations About Youtube Product Categories, Nitin Venkat Mayande

Dissertations and Theses

Traditional marketing models are swiftly being upended by the advent of online social networks. Yet, practicing firms that are engaging with online social networks neither have a reliable theory nor sufficient practical experience to make sense of the phenomenon. Extant theory in particular is based on observations of the real world, and may thus not apply to online social networks. Practicing firms may consequently be misallocating a large amount of resources, simply because they do not know how the online social networks with which they interact are organized.

The purpose of this dissertation is to investigate how online social networks …

A Spline Framework For Optimal Representation Of Semiperiodic Signals, Farzin G. Guilak

Dissertations and Theses

Semiperiodic signals possess an underlying periodicity, but their constituent spectral components include stochastic elements which make it impossible to analytically determine locations of the signal's critical points. Mathematically, a signal's critical points are those at which it is not differentiable or where its derivative is zero. In some domains they represent characteristic points, which are locations indicating important changes in the underlying process reflected by the signal.

For many applications in healthcare, knowledge of precise locations of these points provides key insight for analytic, diagnostic, and therapeutic purposes. For example, given an appropriate signal they might indicate the start or …

A Multivariate Modeling Approach For Generating Ensemble Climatology Forcing For Hydrologic Applications, Sepideh Khajehei

Dissertations and Theses

Reliability and accuracy of the forcing data plays a vital role in the Hydrological Streamflow Prediction. Reliability of the forcing data leads to accurate predictions and ultimately reduction of uncertainty. Currently, Numerical Weather Prediction (NWP) models are developing ensemble forecasts for various temporal and spatial scales. However, it is proven that the raw products of the NWP models may be biased at the basin scale; unlike model grid scale, depending on the size of the catchment. Due to the large space-time variability of precipitation, bias-correcting the ensemble forecasts has proven to be a challenging task. In recent years, Ensemble Pre-Processing …

Multivalent Rechargeable Batteries, Sudhaprasanna Kumar Padigi

Dissertations and Theses

Li⁺ ion batteries have been the mainstay of high energy storage devices that have revolutionized the operating life time of consumer electronic devices for the past two decades. However, there is a steady increase in demand for energy storage devices with the ability to store more energy and deliver them at high power at low cost, without comprising safety and lifetime.

Li-ion batteries have had significant challenges in increasing the amount of stored energy without affecting the overall lifetime and the ability to deliver stored energy. In order to store and deliver more energy, more lithium ions need to …

Evaluating Global Sensitivity Analysis Methods For Hydrologic Modeling Over The Columbia River Basin, Maysoun Ayad Hameed

Dissertations and Theses

Global Sensitivity Analysis (GSA) approach helps to identify the effectiveness of model parameters or inputs and thus provides essential information about the model performance. The effects of 14 parameters and one input (forcing data) of the Sacramento Soil Moisture Accounting (SAC-SMA) model are analyzed by using two GSA methods: Sobol' and Fourier Amplitude Sensitivity Test (FAST). The simulations are carried out over five sub-basins within the Columbia River Basin (CRB) for three different periods: one-year, four-year, and seven-year. The main parameter sensitivities (first-order) and the interactions sensitivities (second-order) are evaluated in this study. Our results show that some hydrological processes …

The Role Of Environmental Dynamics In The Emergence Of Autocatalytic Networks, Joe Fusion

Dissertations and Theses

For life to arise from non-life, a metabolism must emerge and maintain itself, distinct from its environment. One line of research seeking to understand this emergence has focused on models of autocatalytic reaction networks (ARNs) and the conditions that allow them to approximate metabolic behavior. These models have identified reaction parameters from which a proto-metabolism might emerge given an adequate matter-energy flow through the system. This dissertation extends that research by answering the question: can dynamically structured interactions with the environment promote the emergence of ARNs? This question was inspired by theories that place the origin of life in contexts …

Time-Variant Load Models Of Electric Vehicle Chargers, Nicole P. Zimmerman

Dissertations and Theses

In power distribution system planning, it is essential to understand the impacts that electric vehicles (EVs), and the non-linear, time-variant loading profiles associated with their charging units, may have on power distribution networks. This research presents a design methodology for the creation of both analytical and behavioral models for EV charging units within a VHDL-AMS simulation environment.

Voltage and current data collected from Electric Avenue, located on the Portland State University campus, were used to create harmonic profiles of the EV charging units at the site. From these profiles, generalized models for both single-phase (Level 2) and three-phase (Level 3) …

Device, Method, And Algorithm To Assess Changes In Cardiac Output Via Intracardiac Impedance Monitoring, Geoffrey Fredrick Schau

Dissertations and Theses

Cardiac output, the volume of blood pumped by the heart over time, is a powerful clinical metric used by physicians to assess overall cardiac health and patient well-being. However, current cardiac output estimation methods are typically invasive, time-consuming, expensive, or some combination of all three. Patients that receive artificial cardiac pacemaker devices are particularly susceptible to cardiac dysfunction and often require long-term cardiac monitoring support.

This thesis proposes a novel cardiac output monitoring solution which leverages an implantable intracardiac medical device. The principles of traditional impedance cardiography, an established cardiac output monitoring technique in practice for over fifty years, have …

Revealing Structural Organization With Liquid Crystal-Based Spectral Imaging Polarimetry, James Campbell Gladish

Dissertations and Theses

Structural organization refers to the particular ordering of scatterers. Probing structural organization by imaging polarized spectral scatter provides insight into the composition of a medium, and can aid in remote sensing, the identification of tissue pathologies, and material characterization and differentiation. The vector nature of polarized light enables it to interact with optical anisotropies within a medium, while the spectral aspect of polarization is sensitive to small-scale structure. However, many polarization studies have limitations, as they provide qualitative image analysis, incomplete anisotropy information, or both. The ability to image the effects of anisotropy and small-scale structure at multiple wavelengths is …

Engineering Professional Development: Elementary Teachers' Self-Efficacy And Sources Of Self-Efficacy, Donna Louise Webb

Dissertations and Theses

Currently, STEM (science, technology, engineering, and mathematics) is a popular buzz word in P -12 education as it represents a means to advance American competitiveness in the global economy. Proponents of the engineering component of STEM advocate additional benefits in teaching engineering, such as its capacity to engage students in collaboration, and to apply critical thinking, systems thinking, negotiation, and communication skills to solve real-life contextual problems. Establishing a strong foundation of engineering knowledge at a young age will provide students with internal motivation as it taps into their curiosity toward how things work, and it also prepares them for …

Experimental Investigation Of Fiber Reinforced Concrete Beams, Karrar Ali Al-Lami

Dissertations and Theses

Shear strength of fiber reinforced concrete beams was studied in this research project. Three types of fibers were examined: hooked-end steel fiber, crimped-steel fiber, and crimped-monofilament polypropylene fibers. The experimental program included five beam specimens. Two of the beams were control specimens in which one was reinforced with minimum shear reinforcement according to ACI 318, while the other one did not have any shear reinforcement. Each one of the other three specimens was reinforced with one of the above mentioned fibers by 1% volumetric ratio. In addition to the beam specimens, three prisms were also made for each type fiber …

Climate Change Assessment In Columbia River Basin (Crb) Using Copula Based On Coupling Of Temperature And Precipitation, Yueyue Qin

Dissertations and Theses

The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. In the present study, we have used multi-modelled statistically downscaled ensemble of precipitation and temperature variables. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State …

Reversible Circuits Synthesis Based On Exor-Sum Of Products Of Exor-Sums, Linh Hoang Tran

Dissertations and Theses

Power dissipation in modern technologies is an important matter and overheating is a severe concern for both manufacturer (impossibility of introducing new and smaller scale technologies and limited temperature range for operating the product) and customer (power supply, which is especially important for mobile systems). One of the main profits that reversible circuit carries is theoretically the zero power dissipation in the sense that it is independent of underlying technology; irreversibility means heat generation. In the other words, reversible circuits may offer a feasible solution in the future that will aid certain reduction of the power loss.

Reversible circuits are …

Constant Interface Temperature Reliability Assessment Method: An Alternative Method For Testing Thermal Interface Material In Products, Christian Amoah-Kusi

Dissertations and Theses

As electronic packages and their thermal solutions become more complex the reliability margins in the thermal solutions diminish and become less tolerant to errors in reliability predictions. The current method of thermally stress testing thermal solutions can be over or under predicting end of life thermal performance. Benefits of accurate testing and modeling are improved silicon yield in manufacturing, improved performance, lower cost thermal solutions, and shortened test times.

The current method of thermally stress testing is to place the entire unit in an elevated isothermal temperature and periodically measure thermal performance. Isothermally aging is not an accurate representation of …

Behavior Of Reinforced Concrete Beams Retrofitted In Flexure Using Cfrp-Nsm Technique, Salam Al-Obaidi

Dissertations and Theses

A variety of retrofitting methods are used to upgrade existing structures. For example, steel plates and Fiber Reinforced Polymer (FRP) jackets are externally bonded to members to increase their capacity in flexure and shear. However, due to the issue of corrosion these strengthening systems may lose their efficiency with time. FRP materials have been used to strengthen many structural components of different shapes and types. FRP jackets, FRP Strips, and FRP rods have commonly been used to rehabilitate existing structural components. The many advantages of using FRP as strengthening materials have made this material an attractive alternative: advantages such as …

Evaluating The Effects Of A Congestion And Weather Responsive Advisory Variable Speed Limit System In Portland, Oregon, Matthew Blake Downey

Dissertations and Theses

Safety and congestion are ever present and increasingly severe transportation problems in urban areas throughout the nation and world. These phenomena can have wide-ranging consequences relating to safety, the economy, and the environment. Adverse weather conditions represent another significant challenge to safety and mobility on highways. Oregon is not immune from either of these global issues. Oregon Route (OR) 217, to the southwest of the downtown Portland, is one of the worst freeways for congestion in the state and is also subject to the Pacific Northwest's frequently inclement and unpredictable climate. High crash rates, severe recurrent bottlenecks and highly unreliable …

Measuring The Effect Of Vegetated Roofs On The Performance Of Photovoltaic Panels In Combined Systems, Hamid Hawi Kadham Ogaili

Dissertations and Theses

Recent studies suggest that integration of photovoltaic panels with green roofs may improve the performance of both. While vegetation may provide a benefit by reducing the net radiation load on the underside of the photovoltaic (PV) panels, it may also affect convective cooling of panels, and consequently, panel efficiency. Both effects likely diminish with the height of the PV panel above the roof, although placing PV panels too close to the vegetation increases the risk of the plants growing over the edges of, and shading the PV panel. There is a gap in the literature with respect to evaluating these …

A Study Of Microwave Curing Of Underfill Using Open And Closed Microwave Ovens, Aditya Thakare

Dissertations and Theses

As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production.

In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers.

In this study, we compare …

A Metal-Free Approach To Biaryl Compounds: Carbon-Carbon Bond Formation From Diaryliodonium Salts And Aryl Triolborates, Kuruppu Lilanthi Jayatissa

Dissertations and Theses

Biaryl moieties are important structural motifs in many industries, including pharmaceutical, agrochemical, energy and technology. The development of novel and efficient methods to synthesize these carbon-carbon bonds is at the forefront of synthetic methodology. Since Ullmann’s first report of stoichiometric Cu-mediated homo-coupling of aryl halides, there has been a dramatic evolution in transition metal catalyzed biaryl cross-coupling reactions.

Our work focuses on the discovery and development of an unprecedented reagent combination for metal-free cross-coupling. It is hypothesized that direct carbon-carbon bond formation occurs via a triaryl-λ³-iodane and that electrophile/nucleophile pairing is critical for success in the reaction. Proof-of-concept …

Bicyclist Compliance At Signalized Intersections, Samson Ray Riley Thompson

Dissertations and Theses

This project examined cyclist red light running behavior using two data sets. Previous studies of cyclist compliance have investigated the tendencies of cyclists to run red lights on the whole by generalizing different maneuvers to their end outcome, running a red light. This project differentiates between the different types of red light running and focuses on the most egregious case, gap acceptance, which is when a cyclist runs a red light by accepting a gap in opposing traffic.

Using video data, a mathematical model of cyclist red light running was developed for gap acceptance. Similar to other studies, this analysis …

Vortex Identification In The Wake Of A Wind Turbine Array, Aleksandr Sergeyevich Aseyev

Dissertations and Theses

Vortex identification techniques are used to analyze the flow structure in a 4 x 3 array of scale model wind turbines. Q-criterion, Δ-criterion, and λ₂-criterion are applied to Particle Image Velocimetry data gathered fore and aft of the last row centerline turbine. Q-criterion and λ₂-criterion provide a clear indication of regions where vortical activity exists while the Δ-criterion does not. Galilean decomposition, Reynolds decomposition, vorticity, and swirling strength are used to further understand the location and behavior of the vortices. The techniques identify and display the high magnitude vortices in high shear zones resulting from the …

Performance Metrics For Depth-Based Signal Separation Using Deep Vertical Line Arrays, John K. Boyle

Dissertations and Theses

Vertical line arrays (VLAs) deployed below the critical depth in the deep ocean can exploit reliable acoustic path (RAP) propagation, which provides low transmission loss (TL) for targets at moderate ranges, and increased TL for distant interferers. However, sound from nearby surface interferers also undergoes RAP propagation, and without horizontal aperture, a VLA cannot separate these interferers from submerged targets. A recent publication by McCargar and Zurk (2013) addressed this issue, presenting a transform-based method for passive, depth-based separation of signals received on deep VLAs based on the depth-dependent modulation caused by the interference between the direct and surface-reflected acoustic …