Engineering Commons^™

Dynamic Response Of Highway Bridge Superstructures Subjected To Wave Action: Experimental Analysis And Numerical Modeling, Alaa Waleed Hameed

Dissertations and Theses

Bridges are critical lifeline components of the infrastructure network, enabling economies to function under normal conditions and disaster response and recovery missions to take place after extreme events. Therefore, ensuring satisfactory performance increases community resilience and minimizes both human and economic losses. Coastal bridges, which are the focus of this PhD dissertation, are vulnerable to coastal storms. High failure rates of these bridges during two major hurricane events in the mid-2000s have spurred research activities to better understand the wave-induced forces of coastal bridges.

This PhD research represents a continuation effort to build, implement, and introduce new fundamental concepts and …

An Assessment Of The Decision-Making Units' Efficiency In Service Systems, Maoloud Yakhlif Dabab

Dissertations and Theses

Most tools and models of performance and quality of service management are generic and do not solve complex technical systems. The critical components of the system need such tools to assess their efficiency to make a better decision about them. One of the primary objectives in the service systems is to improve the ability of efficiency, effectiveness, and sustainability of critical assets. One of the challenges with improving critical assets is the amount of major capital spending needed to upgrade a technology infrastructure with a high obsolescence rate. This along with usage and reliability issues, makes evaluating mobile cells to …

Design Of A 7-Mhz Portable Direct Conversion Transceiver With Digitally Controlled Keying, Abram Morphew

Dissertations and Theses

This thesis outlines the design of a portable direct conversion transceiver system for the 7-MHz (or 40m) band. This band is popular due to its propagation characteristics which allow for world-wide communication with very low power. The transceiver utilizes a crystal-stabilized local oscillator optimized for frequency agility, low power consumption, and an optimal drive level of +7 dBm. A low power 8-bit microcontroller acts as an interface for either a straight key providing manual Morse code operation or digital logic control from a personal computer. It also acts as a side tone oscillator providing audio feedback to the operator during …

Designing Gates And Architectures For Superconducting Quantum Systems, Sahar Daraeizadeh

Dissertations and Theses

Large-scale quantum computers can solve certain problems that are not tractable by currently available classical computational resources. The building blocks of quantum computers are qubits. Among many different physical realizations for qubits, superconducting qubits are one of the promising candidates to realize gate model quantum computers. In this dissertation, we present new multi-qubit gates for nearest-neighbor superconducting quantum systems. In the absence of a physical hardware, we simulate the dynamics of the quantum system and use the simulated environment as a framework for test, design, and optimization of quantum gates and architectures. We explore three different simulation-based gate design methodologies: …

Facilitating Mixed Self-Timed Circuits, Alexandra R. Hanson

University Honors Theses

Designers constrain the ordering of computation events in self-timed circuits to ensure the correct behavior of the circuits. Different circuit families utilize different constraints that, when families are combined, may be more difficult to guarantee in combination without inserting delay to postpone necessary events. By analyzing established constraints of different circuit families like Click and GasP, we are able to identify the small changes necessary to either 1) avoid constraints entirely; or 2) decrease the likelihood of necessary delay insertion. Because delay insertion can be tricky for novice designers and because the likelihood of its requirement increases when mixing different …

Optimized Xanthene-Based Probes For Pancreatic Cancer Imaging, Ian Ruramai Munhenzva

Dissertations and Theses

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest human malignancies with an extremely poor 5-year survival rate of below 5%. Surgical resection is the most effective treatment of choice because chemotherapy and radiation therapy do not improve life expectancy. Residual tumor after PDAC surgery is common due to a lack of PDAC targeted intraoperative contrast agents to confirm clear margins.

Fluorescence imaging has the potential to improve surgery outcome and PDAC patients' survival rate via the use of highly PDAC-specific molecular probes to facilitate tumor identification. This thesis describes the application of a focused library of benzoxanthene fluorophores for …

Chehalis River And Tributary Water Quality And Hydrodynamic Modeling: Model Setup, Calibration Analysis For 2013-2015, Tel Jensen

Dissertations and Theses

The Chehalis River is located in southwest Washington State. Its headwaters are in the Willapa Hills, and it drains parts of the Doty Hills, the western foothills of the Cascade Mountains, and the southern Olympic Mountains. The Chehalis River is over 125 miles long and its basin is over 2000 square miles spanning parts of seven counties and diverse land uses.

CE-QUAL-W2 is a widely used two-dimensional (vertical and longitudinal) hydrodynamic and water quality model developed by the US Army Corp of Engineers and the Water Quality Research Group at Portland State University. Version 4.2 includes the ability to run …

A Numerical Investigation Of Microgravity Evaporation, Daniel Peter Ringle

Dissertations and Theses

Evaporation is important to myriad engineering processes such as cooling, distillation, thin film deposition, and others. In fact, NASA has renewed interest in using cabin air pressure evaporation as a means to recycle waste water in space. As one example, NASA recently conducted experiments aboard the International Space Station (ISS) to measure evaporation rates in microgravity and to determine the impacts of porous structure on the process. It has long been assumed that differences in evaporation rates between 1-g₀ and microgravity are small. However, discrepancies by as much as 40% have been observed in practice. The assumption now …

Aggregated Water Heater System (Awhs) Optimization For Ancillary Services, Manasseh Obi

Dissertations and Theses

In this dissertation, I present a two-stage optimization routine that schedules an Aggregated Water Heater System (AWHS) to concurrently provide three utility ancillary services, namely, frequency regulation, frequency response, and peak demand mitigation.

Water heaters can be controlled to manage their energy take, the amount of energy a water heater can absorb upon command. The AWHS is a model aggregation of thousands of water heaters, the energy take and power characteristics of which are based on U.S Census household data and usage behavior patterns. The aggregate energy take available in the AWHS may be dispatched en masse for participation in …

Scanning Electron Microscopy (Sem) Investigation Of Morphology Changes In The Reduction Of Silica Nanoparticles To Elemental Silicon, Allison M. Cairns

University Honors Theses

The application of silicon nanoparticles varies from energy storage materials, to drug-delivery, and molecular recognition. Various chemical and physical properties of the Si nanoparticles arise from their morphology. This paper aims to reveal the morphology of Si nanoparticles following magnesiothermic reduction of silica (SiO₂) nanoparticles. Two sets of SiO₂ nanoparticles were used, commercially available NanoXact nanoparticles and laboratory-synthesized Stöber nanoparticles. A Zeiss Sigma VP FEG SEM was used to examine the morphology. Following the magnesiothermic reduction, the nanoparticles were etched with HF. Ten sets of images were taken of both Stöber and NanoXact nanoparticles: 1,2: the SiO …

Absorptive Reflectionless Filters, Guy Barry Lemire

Dissertations and Theses

For many applications requiring some sort of signal filtering or signal conditioning, the filter requirements are usually approached with a single purpose in mind, which is to maximize both passband signal amplitude and stop band signal attenuation to the load with little to no thought given to what happens to the stop band signal energy. Many conventional filters have very poor impedance matching in the stopband resulting in reflected energy or large return loss (S₁₁). This reflected energy can then cause interactions with adjoining system components which do not in general respond well to spurious reflected energy and …

Power Efficiency Enhancement And Linearization Techniques For Power Amplifiers In Wireless Communications, Haider Al-Kanan

Dissertations and Theses

Wireless communication systems require Power Amplifiers (PAs) for signal transmissions. The trade-off between power efficiency and nonlinear distortion in PAs degrades the communication performance. Thus, power efficiency and nonlinearity are two main concerns of operating PAs in communication systems. Nonlinear behavioral models are typically used to quantify and mitigate the distortion effects of PAs on communication systems. This dissertation presents an estimation approach for modeling and linearizing the PA Amplitude-to-Amplitude (AM/AM) nonlinearity using the design specifications of PAs, such as gain, the third-order intercept point, and 1dB compression point. Furthermore, an enhanced approach for modeling solid-state power amplifiers is developed …

Narrowing The Cognitive Distance Between Engineers And Customers: A Novel Approach, Based On Fuzzy Cognitive Mapping, Byung Sung Yoon

Dissertations and Theses

During concept development, product developers consider product users and their future experience, cost, development and manufacturing efficiency, product function/quality, and differentiation of the product in the market. Development teams often struggle to adequately address all of these considerations, due to the following reasons: (1) Differences in technological and experiential knowledge, methods used, and communication styles that make it difficult for customers/user, marketing, and engineering to communicate effectively. As a result, important factors may not be sufficiently considered. (2) Product design factors, including technological alternatives, functions, features, benefits, and customer value are interdependent: in some cases, customers are willing to sacrifice …

Classifying Seabed Parameters From Normal Incidence Reflections: Model Comparison And Inversion Technique, Megan Frantz

Dissertations and Theses

As of the year 2019, only about five percent of the seafloor has been topologically mapped and classified for type (e.g., sand, silt, gravel). To rapidly survey the seabed from surface ships or underwater vehicles, acoustic remote sensing methods are needed. In this thesis, acoustic measurements and inverse modeling is investigated as a way to classify seabed type based on estimating parameters such as density, sound speed, and interface roughness. The method uses normal incident acoustic measurements that can be made using either a single beam echo sounder or the normal incident beams from a side scan sonar. The inverse …

Optimal Boundary Detection Using Autonomous Mobile Sensors, Phillip Justin Kearns

Dissertations and Theses

A fundamental challenge to modern science and engineering is the ability to rapidly and accurately determine the spatial extent of environmental phenomena. In monitoring the spread of hazardous pollution, for example, all points with pollutant concentration above or below a fixed threshold can be considered as two classes in a binary classification problem. In this instance, the goal is to accurately estimate the decision boundary as quickly as possible. To generate models and predictions, scientists must choose their sampling locations from a vast array of possibilities. This thesis develops a policy for determining the optimal sample locations for a fixed …

Undrained Cyclic Shear Resistance Of Low Plastic Silts, Rawan Almoumen

Dissertations and Theses

A magnitude 9 Cascadia Subduction Zone earthquake is expected to trigger widespread liquefaction in loose material in Oregon. The geotechnical engineering studies have determined that the Willamette Silts may be susceptible to liquefaction or cyclic softening, as their plasticity indices ranges between non-plastic to low plasticity. While the majority of past studies have focused on liquefaction of sand and cyclic behavior of clays, there is not enough data on the cyclic response behavior of silty soils and the liquefaction susceptibility of these soils. A research focus in the geotechnical engineering program at Portland State University revolves around is performing cyclic …

Characterization Of Inertial Particles In The Turbulent Wake Of A Porous Disk, Kristin Nichole Travis

Dissertations and Theses

This study presents the findings of a wind tunnel experiment investigating the behaviour of micrometric inertial particles in the turbulent wake of a stationary porous disk. Various concentrations [Φ_v ∈ (2.95 x 10^-6 - 1.22 x 10^-5)] of polydisperse water droplets (diameter 13-41 µm) are compared to sub-inertial tracer particles. Hot-wire anemometry, phase Doppler interferometry and particle image velocimetry were implemented in the near and far wake regions to study the complex dynamics of the particles. Turbulence statistics and particle size distributions are presented and used to explore the particle wake interaction.

The Optimization Of Machining Parameters For Milling Operations By Using The Nelder Mead Simplex Method, Yubin Lee

Dissertations and Theses

Machining operations need to be optimized to maximize profit for computer numerical control (CNC) machines. Although minimum production time could mean high productivity, it can not guarantee maximum profit rate in CNC milling operations. The possible range of machining parameters is limited by several constraints, such as maximum machine power, surface finish requirements, and maximum cutting force for the stability of milling operations. Among CNC machining parameters, cutting speed and feed have the greatest effect on machining operations. Therefore, cutting speed and feed are considered as main process variables to maximize the profit rate of CNC milling operations.

A variety …

Robust Maximum Flow Network Interdiction Problem, Darshan Rajesh Chauhan

Dissertations and Theses

In this thesis, a maximum flow-based network interdiction problem considering uncertainties in arc capacities and interdiction resource consumption is solved. The problem consists of two entities with opposing objectives: the goal of the adversary is to maximize the flow of illicit drugs through the network, while the goal of the interdictor is to minimize the maximum flow by completely interdicting arcs given a specified amount of resources. Lack of complete information about the usage patterns of the transportation network by the adversary results in an uncertain estimate of arc capacity and resources required for interdiction by the interdictor. To account …