Engineering Commons^™

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 …

Improved Denoising Of Structural Vibration Data Employing Bilateral Filtering, Ning Liu, Thomas Schumacher

Civil and Environmental Engineering Faculty Publications and Presentations

With the continuous advancement of data acquisition and signal processing, sensors, and wireless communication, copious research work has been done using vibration response signals for structural damage detection. However, in actual projects, vibration signals are often subject to noise interference during acquisition and transmission, thereby reducing the accuracy of damage identification. In order to effectively remove the noise interference, bilateral filtering, a filtering method commonly used in the field of image processing for improving data signal-to-noise ratio was introduced. Based on the Gaussian filter, the method constructs a bilateral filtering kernel function by multiplying the spatial proximity Gaussian kernel function …

Performance Of Us Concrete Highway Bridge Decks Characterized By Random Parameters Binary Logistic Regression, Omar Ghonima, Jason C. Anderson, Thomas Schumacher, Avinash Unnikrishnan

Civil and Environmental Engineering Faculty Publications and Presentations

This study employs a random parameters binary logistic regression (LR) to characterize the impact of environmental and structural parameters on concrete highway bridge deck deterioration nationwide. Two specific gaps in the literature are addressed: (1) the use of a nationwide dataset for analysis, and (2) the implementation of a methodology to account for unobserved heterogeneity. A total of 3,262 bridge deck deterioration observations derived from the authors’ nationwide concrete highway bridge deck performance inventory (NCBDPI) database were used in this study. The deterioration rate (DR) was computed as the decrease in the concrete bridge deck condition rating ( …

Ten Questions Concerning The Implications Of Carpet On Indoor Chemistry And Microbiology, Sarah R, Haines, Rachel I. Adams, Brandon E. Boor, Thomas A. Bruton, John Downey, Andrea R. Ferro, Elliott T. Gall, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices …

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 …

Sea Level, Tidal, And River Flow Trends In The Lower Columbia River Estuary, 1853-Present, Stefan Talke, Andrew Mahedy, David A. Jay, Patrick Lau, Conrad Hilley, Amanda Hudson

Civil and Environmental Engineering Faculty Publications and Presentations

Few tidal records are available pre-1900 for the Pacific Ocean. We improve data coverage by recovering historical tabulations and digitizing analog tide rolls from Astoria, Oregon for 1853-1876. Nearly 13,500 overlapping images of tides from 1855-1870 were digitized at a 6 minute resolution using a line-finding algorithm. Available hourly and high/low tabulations were also digitized, as were nearby hourly records from 1933-1943. Uncertainty was assessed by evaluating manual staff measurements, historical documents, and leveling surveys. Results suggest that uncertainty in mean sea level varies from ± 0.07m (early 1850s) to ± 0.03m (1867-1876) and is driven primarily by datum and …

Inversion Of Head Waves In Ocean Acoustic Ambient Noise, Jie Li, Peter Gerstoft, Martin Siderius, Jun Fan

Electrical and Computer Engineering Faculty Publications and Presentations

The virtual head wave is produced through cross-correlation processing of signals containing the real, acoustic head wave. The virtual head wave has the same phase speed as the head wave, but the travel time is offset, thus the term virtual. The virtual head wave, like the real head wave, propagates in a direction corresponding to the seabed critical angle. The virtual head wave travel time varies with array depth and water column depth. However, in a refracting environment, the travel time is also dependent on the depth-dependent sound speed profile. Previously, the virtual head wave was shown as observable from …

Improved Estimation For Saleh Model And Predistortion Of Power Amplifiers Using 1-Db Compression Point, Haider Al Kanan, Xianzhen Yang, Fu Li

Electrical and Computer Engineering Faculty Publications and Presentations

This paper proposes an improved estimation approach for modelling RF power amplifiers (PAs) using the Saleh behavioural model. The proposed approach is appropriate for solid-state PA technologies. The 1-dB compression point of the PA is included in the estimation approach to improve the estimation of the Saleh coefficients. Thus, expressions are derived to describe the relationship between the parameters of the Saleh model and the manufacturing specifications of PAs: gain (G), third-order intercept point (IP₃) and 1-dB compression point (P_1dB). This method is a simple estimation of a memoryless amplitude-to-amplitude (AM/AM) nonlinearity to benefit RF designers …

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 …

A Polarity-Based Approach For Optimization Of Multivalued Quantum Multiplexers With Arbitrary Single-Qubit Target Gates, Kevin Jin, Tahsin Soffat, Justin Morgan, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

Previous work has provided methods for decomposing unitary matrices to series of quantum multiplexers, but the multiplexer circuits created in this way may be highly non-minimal. This paper presents a new approach for optimizing quantum multiplexers with arbitrary single-qubit quantum target functions and ternary controls. For multivalued quantum multiplexers, we define standard forms and two types of new forms: Fixed Polarity Quantum Forms (FPQFs) and Kronecker Quantum Forms (KQFs). Drawing inspiration from the usage of butterfly diagrams, we devise a method to exhaustively construct new forms. In contrast to previous butterfly-based methods, which are used with classical Boolean functions, these …

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 …

Toilet Alarms: A Novel Application Of Latrine Sensors And Machine Learning For Optimizing Sanitation Services In Informal Settlements, Phillip Nicholas Turman-Bryant, Taylor Sharpe, Corey L. Nagel, Lauren Stover, Evan A. Thomas

Systems Engineering Faculty Publications and Presentations

The cost-effectiveness and reliability of waste collection services in informal settlements can be difficult to optimize given the geospatial and temporal variability of latrine use. Daily servicing to avoid overflow events is inefficient, but dynamic scheduling of latrine servicing could reduce costs by providing just-in-time servicing for latrines. This study used cellular-connected motion sensors and machine learning to dynamically predict when daily latrine servicing could be skipped with a low risk of overflow. Sensors monitored daily latrine activity, and enumerators collected solid and liquid waste weight data. Given the complex relationship between latrine use and the need for servicing, an …

Connecting Offshore Floating Wind To The Western Electricity Grid: Transmission Options Decision Modeling, Bill Henry

Engineering and Technology Management Student Projects

The purpose of this project is to obtain stakeholder views on a range of aspects relating to a proactive planning process to build transmission facilities in coordination with development of floating offshore wind (OSW) in southern Oregon and northern California. In the event that a transmission planning process to examine the potential need to assess and build transmission facilities to connect these wind resource areas is launched at a future date, the results of this study will assist planners by obtaining initial stakeholder views on the breadth of choices that should be considered, and more importantly, provide key insights on …

Fuzzy Cognitive Maps-Based Switched-Mode Power Supply Design Assistant System, Yi Kuang, Zhiyong Johnny Zhang, Bin Duan, Pei Zhang

Engineering and Technology Management Faculty Publications and Presentations

Traditional engineering design approaches primarily solve technical problems and often ignore the importance of human factors. To reduce human errors and workload in power electronics, this paper proposes a switched-mode power supply design (SMPS) assistant system based on Fuzzy Cognitive Maps (FCMs). This system incorporates both technical requirements and human factors that involve designers' knowledge and skills in the SMPS design domain. First, we identify the critical concepts from power management lab kits and power electronics books, and extract latent sub-skills of SMPS design using exploratory factor analysis to build the starting concept list of FCM. Second, we use factor …

Analytical And Field Verification Of A 3d Hydrodynamic And Water Quality Numerical Scheme Based On The 2d Formulation In Ce-Qual-W2, Hussein Ali Mahdi Al-Zubaidi, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

A new 3D hydrodynamic model was developed to simulate water quality transport in surface waterbodies. The governing equations are the continuity equation, free surface equation, momentum equation and transport equation. The 2D numerical scheme of CE-QUAL-W2 was expanded in three dimensions and modified to solve for the free surface elevation. A time splitting technique was employed to solve the momentum and transport equation. The numerical formulation of the 3D scheme used a novel solution, which resulted in a tri-diagonal matrix form for solving the free surface equation rather than a more computationally intensive penta-diagonal matrix solution. In addition, the hydrodynamic …

A Study Of The Competitiveness Of Autonomous Delivery Vehicles In Urban Areas, Miguel A. Figliozzi, Dylan Jennings

Civil and Environmental Engineering Faculty Publications and Presentations

The rapid growth of e-commerce and package deliveries across the globe is demanding new solutions to meet customers’ desire for more and faster deliveries. This research focuses on the cost competitiveness of autonomous air and ground delivery vehicles. Three types of autonomous vehicle are analyzed: drones, sidewalk autonomous delivery robots (SADRs), and road autonomous delivery robots (RADRs). Autonomous vehicles are compared against a typical delivery van. The impact of capacity, range and time constraints are analyzed. Results show that each type of autonomous delivery vehicle is suitable in different scenarios and can therefore complement each other to reduce costs or …

A Study Of Road Autonomous Delivery Robots And Their Potential Impacts On Freight Efficiency And Travel, Dylan Jennings, Miguel A. Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

Road autonomous mobile robots have attracted the attention of delivery companies and policy makers for their potential to reduce costs and increase urban freight efficiency. Established delivery companies and new startups are investing in technologies that reduce delivery times and/or increase delivery drivers’ productivity. In this context, the adoption of Road Automatic (or Autonomous) Delivery Robots (RADRs) has a growing appeal. Several RADRs are currently being tested in the United States. The key novel contributions of this research are: (a) an analysis of the characteristics and regulation of RADRs in the US and (b) a study of the relative travel, …

Understanding Roundabout Safety Through The Application Of Advanced Econometric Techniques, Hamsa Abbas Zubaidi, Jason C. Anderson, Salvador Hernandez

Civil and Environmental Engineering Faculty Publications and Presentations

Intersections present a significant safety concern, as such in an effort to reduce the more serious injuries occurring at or near intersections, many jurisdictions have turned to implementing roundabouts. Despite the advantages that roundabouts provide, crashes still occur, and less severe crashes are on the rise. The study presented in this paper investigates a crash-based analysis to better understand the factors that may influence less severe crashes to those of more severe crashes given various roundabout configurations and crash types. Using Oregon’s crash database from 2011 to 2015 a series of log likelihood ratio tests were conducted to validate that …

Factors Affecting Injury Severity In Vehicle-Pedestrian Crashes: A Day-Of-Week Analysis Using Random Parameter Ordered Response Models And Artificial Neural Networks, Seyedmirsajad Mokhtarimousavi, Jason C. Anderson, Atorod Azizinamini, Mohammed Hadi

Civil and Environmental Engineering Faculty Publications and Presentations

The high number of vehicle–pedestrian crashes in the United State has gained increased attention among transportation safety analysts in recent years. Being directly exposed to the collision force makes pedestrians more prone to becoming severely injured when in crash than other road users. Considering the fact that pedestrian-involved crashes is a serious public health problem, the current study’s aim is to investigate the contributing factors associated with injury severity of pedestrian crashes by time-of-week. Separate injury severity models for weekday and weekend crashes were developed, and the overall stability of the model estimates was examined through likelihood ratio tests. For …

Carbon Emissions Reductions In Last Mile And Grocery Deliveries Utilizing Autonomous Vehicles, Miguel A. Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

New driverless air and ground vehicles are being launched and tested to deliver products or services in the areas of retail, groceries, and healthcare. This research focuses on the efficiency of autonomous (driverless) delivery vehicles in terms of vehicle-miles, energy consumption, and carbon emissions. Drones or UAVs, sidewalk autonomous delivery robots (SADRs), and road autonomous delivery robots (RADRs) vehicles carbon emissions are compared against emissions from an electric van (e-van), a conventional internal combustion engine van, and driving to a store utilizing electric and conventional vehicles. The impacts of vehicle capacity, range, and time constraints are analyzed as well as …

Performance Evaluation Of A Carbon Nanotube Sensor For Fatigue Crack Monitoring Of Metal Structures, Shafique Ahmed, Thomas Schumacher, Erik T. Thostenson, Jennifer Mcconnell

Civil and Environmental Engineering Faculty Publications and Presentations

This article describes research that investigated the ability of a carbon nanotube (CNT) sensor to detect and monitor fatigue crack initiation and propagation in metal structures. The sensor consists of a nonwoven carrier fabric with a thin film of CNT that is bonded to the surface of a structure using an epoxy adhesive. The carrier fabric enables the sensor to be easily applied over large areas with complex geometries. Furthermore, the distributed nature of the sensor improves the probability of detecting crack initiation and enables monitoring of crack propagation over time. Piezoresistivity of the sensor enables strains to be monitored …

Storm Tide Amplification And Habitat Changes Due To Urbanization Of A Lagoonal Estuary, Philip Orton, Eric W. Sanderson, Stefan Talke, Mario Giampieri, Kytt Macmanus

Civil and Environmental Engineering Faculty Publications and Presentations

In recent centuries, human activities have greatly modified the geomorphology of coastal regions. However, studies of historical and possible future changes in coastal flood extremes typically ignore the influence of geomorphic change. Here, we quantify the influence of 20th-century man-made changes to Jamaica Bay, New York City, on present-day storm tides. We develop and validate a hydrodynamic model for the 1870s based on detailed maps of bathymetry, seabed characteristics, topography, and tide observations for use alongside a present-day model. Predominantly through dredging, landfill, and inlet stabilization, the average water depth of the bay increased from 1.7 to 4.5 m, tidal …

Accessibility And Equity Analysis Of Common Carrier Parcel Lockers At Transit Facilities In Portland, Oregon, Katherine Keeling, Jaclyn S. Schaefer, Miguel Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

Transit goals have typically focused on commuter trips but facilitating urban last-mile freight logistics is a potential strategy to increase transit ridership and mitigate the demands of parcel distribution on the transportation network. Presently, most parcel lockers operate out of private businesses, but consumer surveys have found that transit users may be interested in locker facilities at transit connections. The implementation of an unmanned, secure, common carrier parcel locker system could have benefits for non-transit users as well. Consolidation of deliveries is expected to benefit courier companies by allowing operations at increasingly competitive rates, and retailers and consumers benefit from …

An Empirical Study Of The Impacts Of Bicycles On Passenger Car Speeds On Urban Roads Without Bicycle Lanes, Jaclyn S. Schaefer, Miguel Figliozzi, Avinash Unnikrishnan

Civil and Environmental Engineering Faculty Publications and Presentations

Higher bicycle mode share has been suggested as part of a solution to reduce the burden of congestion in urban areas. As strategies to promote bicycling are implemented, concerns have been raised by some road users and stakeholders citing simulation based traffic studies that indicate that an increase in the bicycle mode share generates major travel time delays via reduced vehicle speeds unless bicycle lanes are provided. The current research investigates the effects bicycles may have on motorized vehicle speeds on a variety of lower speed and volume urban roads without bicycle lanes. A detailed comparative analysis of passenger car …

A Quantum Algorithm For Automata Encoding, Edison Tsai, Marek Perkowski

Electrical and Computer Engineering Faculty Publications and Presentations

Encoding of finite automata or state machines is critical to modern digital logic design methods for sequential circuits. Encoding is the process of assigning to every state, input value, and output value of a state machine a binary string, which is used to represent that state, input value, or output value in digital logic. Usually, one wishes to choose an encoding that, when the state machine is implemented as a digital logic circuit, will optimize some aspect of that circuit. For instance, one might wish to encode in such a way as to minimize power dissipation or silicon area. For …