A need exists to develop a non-destructive testing technique that can identify
the formation and propagation of diagonal tension cracks in conventionally
steel reinforced concrete deck girder (RCDG) highway bridges in the State of
Oregon. Such a technique could be included into a structural health
monitoring (SHM) system installed on...
With the miniaturization of microelectronics and increase of processor speeds in the last few decades, thermal management is drastically affecting overall packaging and system capabilities. Due to the special needs introduced, research focusing on microscale cooling has increased. This study combines the positive characteristics of single- and two-phase flows in...
A brake-based wheel speed control system for a rear-wheel drive vehicle is developed and simulated in this thesis. The OSU mini-Baja vehicle team will use this study in the development and implementation of a similar system for upcoming competitions. Vehicle submittals must differ to a specified degree from previous year’s...
Aquatic insect population counts can be a good indicator of the health, or water quality, of rivers and streams. Stoneflies (Plecoptera) are particularly susceptible to pollution in streams. However, today’s current method for obtaining these population counts requires biologists to examine individual specimens under a microscope for identification to the...
A distinct characteristic of legged locomotion is its periodic nature. This periodic motion, in the form of a periodic orbit, has been the target of many walking and running control strategies. The spring loaded inverted pendulum (SLIP) has become a popular model of sagittal plane locomotion, exhibiting behavior characteristic of...
Normal gait of human is believed to be an adapted motor control result of optimal behavior of individual. Normal gait would be altered by aging or injury without being perceived. Subtle changes in gait which is not easy to detect, can cause many serious problems including joint pains and even...
The droplet formation process in the vicinity of the nozzle exit and the behavior of a spreading droplet during impingement on a smooth glass surface were studied. Two nozzle geometries were tested. The first case was a stiff stainless steel nozzle plate 0.787 mm thick. The second case was a...
Extending the flight time of an autonomous unmanned air vehicle by soaring is
considered. A suboptimal controller is developed and successful static soaring is
demonstrated with a 6 degree of freedom glider model. Altitude gain rates of between
¼ and ½ m/s are achieved with this simple implementation.
A hybrid...
Product design is often driven by customer needs and desires. In this case the customer is the US military, and the desire is to have a cooling unit small enough and light enough to incorporate into hazard suits for use in desert combat. The Micro technology-based Energy and Chemical Systems...
Design and preliminarily characterization of two thermally-actuated pumps is presented
in this thesis. The unique feature of both pumps is the presence of periodic asymmetrical
structures on the channel walls. Two heat transfer effects are used with surface
asymmetry to generate forces that drive the fluid in a preferential direction...
Background: Hip replacements are considered routine operations which improve the quality of life in patients by reducing pain and restoring function. There are many variations in prostheses with varying benefits and disadvantages.
Methods: Literature from the United States and Europe was collected on total hip replacements between 2001 and the...
Proper orthogonal decomposition (POD) in conjunction with the Galerkin projection has been used as a model reduction technique for the tractable real-time control of high-dimensional systems. While POD based model reduction may improve the tractability of high-dimensional models, the nonlinear POD based model may be impractical for control due to...
An experimental study of the near-field flow structure produced by an incompressible turbulent Acoustically Self-Excited Jet (ASEJ) in a large enclosure using Particle Image Velocimetry (PIV) is presented. The salient feature of this jet is that it provides an increase in near-field mixing and turbulence without additional external power input....
A large part of low-back pain occurrences are due to disc herniation or prolapse of the nucleus pulposus. An alternative technique to existing treatments of low back pain includes nucleus pulposus replacement by an artificial material to relieve pain and restore normal function. To date, there has been a deficiency...
For piezoelectric stack (PZT) driven droplet generator, the driving waveform
and driving frequency effect on liquid filament shape and droplet characteristics have
been experimentally studied. The experimental study was based on a PZT driven
droplet generator with known geometric design parameters and working fluid
properties. A lumped-element-model (LEM) constructed to...
It is crucial for the development of high quality products that design requirements are identified and clarified as early as possible in the design process. In many projects the design requirements and design specifications evolve during the project cycle. Shifting needs of the customer, advancing technology, market considerations and even...
An experiment was conducted to examine the possible impact of an engineering design and problem solving process overview document on knowledge management and capture. A process overview document was first created. Next, two multi-disciplinary design teams worked over a two-week span to develop concepts to address a problematic opportunity. One...
It is hypothesized that increases in pressure drop due to vapor generation during boiling in microchannels can be reduced by extraction of vapor at its point of inception. Ultimately, this local vapor extraction decreases the pressure drop required to drive the flow through a fractal-like branching, microchannel flow network within...
Students participating in international engineering internships are still relatively rare. It is commonly held that more engineering students would choose to intern abroad if there were role models available, as there are in other disciplines. Profiles of past students, participants, and Alumni serve as role models to perspective students allows...
Oregon Department of Transportation’s bridge no. 9743b is a multi-span, two-girder steel deck bridge connecting the busy interstates 5 and 205. Vertical cracks have been detected in the welded girder-to-crossbeam connections at the bents. Distortion-induced fatigue is suspected to be responsible for the cracking. Linear elastic beam analysis, 2-D and...
Air travel presents several problems for passengers with disabilities.
One in particular is how they get from their wheelchair and to an aircraft seat.
The commonly used manual transfer method is hazardous to the assistants
and the passenger. There are other alternatives, but they have plenty of room
for improvement....
People often grow increasingly culturally confused when spending significant amounts of time in a foreign land. Identity can become lost only to reform in the image of the host society. This thesis presents a creative nonfiction series of essays that explore the author’s loss of self and contextual identity, the...
An experimental study of absorption of ammonia into a constrained thin film of ammonia-water solution is presented. A large aspect ratio microchannel with one of its walls formed by a porous material is used to constrain the thickness of the liquid film. Experiments were performed at a pressure of 1,...
Driven by the need for high energy-density power sources, demand has
stimulated the development of small-scale engines. A small-scale engine
with a fuel supply could replace batteries and utilize higher energy-density
liquid hydrocarbon fuels; such an advance could deliver a new age of
portable devices. Currently, operable small-scale engines exist;...
Droplet formation from a flexible nozzle plate driven by a prescribed-waveform excitation of a piezoelectric is numerically investigated using a computational fluid dynamics (CFD) model with the VOF method. The droplet generator with a flexible nozzle plate, which is free to vibrate due to the pressure acting on the plate,...
Transportation plays such an important role in daily living that, without it, a person might be totally homebound. The nation’s air travel system for persons with disabilities is an area of substantial dissatisfaction, with both passengers and the airline industry recognizing the need for improvement. One of the major concerns...
A PID controller was designed to control the performance of an oil-heated fractal-like branching microchannel desorber for use in an ammonia-absorption refrigeration system. Both the amount and concentration of ammonia refrigerant generated at the desorber can be controlled by choosing the rectified circulation ratio as the controlled variable in a...
The behavior of a metal vapor plasma arc in a vacuum arc remelting (VAR) furnace is believed to contribute to the formation of defects in reactive metal and super-alloy ingots. Industry standard instrumentation, which includes electric current and voltage measurements, can asses the stability of an arc but cannot predict...
A Mixed Reactant Single Chamber (MRSC) Fuel Cell is a relatively recent concept in the field of fuel cell engineering originally developed in the late 1950’s. Typical fuel cells have separated reactants (a separated fuel and oxidizer) that react on their usually non-selective electro-catalytic materials. A mixed reactant fuel cell...
Coordinating multiple robots to achieve a complex task requires solving two distinct control problems: the high-level control problem of ensuring that each robot aims to perform a useful task (e.g., coordination) and the low-level control problem of ensuring that each robot actually performs the correct actions to achieve its task...
A non-intrusive measurement technique for direct quantitative thermal visualization of channel wall temperatures in two phase microchannel flows using infrared thermography (IRT) is presented. Specifically, the measurement of top channel wall temperatures in a fractal-like branching microchannel silicon heat sink during flow boiling is demonstrated and thoroughly documented. Obtaining quantitative...
Introduction Over the past century, great technological advances have enabled high-speed communication and transportation across the globe. This technology trend combined with the needs of continuous expansion of market place has motivated major corporations not to restrict their business activities to within a single principality. Engineering design activities can take...
Flow separation is an important phenomenon in fluid dynamics because of the effect it has on lift and drag on immersed bodies. Areas of swirl within a separated flow region may have a distinct effect on the surface forces, modifying the lift and drag characteristics. A correlation between the passage...
Identification and population counts of soil mesofauna can be an
important tool for soil ecologists to determine the soil biodiversity. Information
provided from population counts can give insight to soil ecologists about the
effects of human land use, monitoring soil and water health, benefits of soil
biodiversity in agriculture, and...
In many composites, fiber bridging develops as part of the fracture process. Fiber bridging invalidates many toughness evaluation methods such as the ASTM E399 and complicates the identification of crack length, which is a necessary parameter in energy methods. In order to measure the toughness of fiber bridging composites, an...
Field biologists are in need of more specialized and technical equipment than they are able to produce on their own in order to collect data more efficiently or gather data that is not currently available. This presents a challenge for design engineers because these products are typically highly specialized and...
An experimental study of thermally actuated pumping of a single-phase, single-component fluid is presented in the context of thermal management of a heat source. The prominent feature of this pumping method is that the very heat that is to be removed from the heat source causes a net fluid motion....
Based on experimental investigations the present study evaluates flow instability and
void fraction in a fractal-like branching microchannel network with rectangular cross-section. The hydraulic diameter of the channels ranged from 308μm at the inlet to 143μm at the outlet. The flow network used is characterized by set branching ratios for...
Two-phase gas-liquid flows in microscale fractal-like branching channel flow networks were experimentally studied to assess the validity of existing void fraction correlations and flow regimes based on superficial gas and liquid velocities. Void fractions were assessed using two different methods. First, void fraction data were acquired using a High-Speed-High-Resolution (HSHR)...
The current proliferation of portable electronic devices for personal
communication, business and entertainment has created a demand for high energy density
power supplies. A hydrocarbon fuel with a conversion efficiency of over
15% can provide greater energy density than current battery technology for these
applications. Current micro-scale heat engines do...
The thermal wave technique has been explored for the use of liquid thermal conductivity measurement and flow property diagnostics in this dissertation. For liquid thermal conductivity measurements, an experimental technique based on the thermal wave approach is developed. A stainless steel strip functions as both a heating element and a...
A particle image velocimetry system was established to determine flow fields in low Reynolds number flows through a branching flow network. Due to the fabrication procedure of the test device, flows were limited to a Reynolds number of 1.5 in the largest channel. Data was acquired at each channel inlet,...
An optical diagnostic system capable of measuring angular displacements in a torsionally loaded shaft through noncontact means has been developed. Conventional
torsion diagnostic mechanisms must come in contact with the shaft to be analyzed. The signal-to-noise ratio response of conventional systems is compromised by dirt and wear. Another consequence of...
A one-dimensional numerical model has been developed to study diabatic and adiabatic
flow boiling in microchannels. This model accounts for developing flow effects and
variable property effects. The model uses correlations for void fraction and two-phase
multipliers found in the literature. The model has been used to study the performance...
A hypothesis used to explain the relationship between timber harvesting
and landslides is that tree roots add mechanical support to soil, thus increasing
soil strength. Upon harvest, the tree roots decay which reduces soil strength and
increases the risk of management -induced landslides. The technical literature
does not adequately support...
Risk is a crucial decision factor besides traditional cost and performance during collaborative decision making in a distributed environment. Three main challenges exist: 1) stakeholders' different perspectives and/or diverse cultures can lead to inconsistent risk probability evaluations; 2) risk consequence is hard to be quantified in concrete unit; 3) risk...
At the start of the 21st century much of the focus of aircraft design has been turned to unmanned aerial vehicles (UAVs) which generally operate at much lower speeds in higher risk areas than manned aircraft. One subset of UAVs are Micro Air Vehicles (MAVs) which usually are no larger...
An experimental study was performed to investigate the effect of
flow channel geometry on fully developed turbulent flow in "clean" rod
bundle flow channels. This information was sought to obtain a better
understanding of crossflow mixing between rod bundle subchannels. The
experiments were performed in water with a Reynolds number...
Mechanical design is often based on formal methodologies such as Quality Function Deployment. Techniques to quantitatively account for attractability, sensory perception, and affective design have been successfully incorporated into these methods and are receiving growing acceptance across many industries. Although the adoption of these methods marks a large improvement for...
Ever since composite laminate technology was introduced into the aerospace and automotive industry, there has been a need to fully understand the damage progression experienced by composite laminated plates in the presence of a notch. While numerous research studies have been conducted on this matter when subjected to in-plane loads,...
This thesis addresses numerical simulation of flow maldistribution in microchannels. Microchannels are often associated with two phase-flows which can generate many problems such as plugging the channel or perturbing the flow. In this study we have used CFD and fully resolved technique to simulate what would happen in the case...
Droplet and spray impingement cooling are typically used in high heat flux
thermal management. In this thesis, droplet impingement and evaporation heat transfer
characteristics are determined from measured spatially- and temporally- varying fluid
and surface temperatures. Unique to this study is the documentation of the effects of
using a nanofluid...
The rapid advance of concrete engineering in the
West has made necessary reliable information as to the
strength qualities of the most important marketable, sands
In the eastern states, theory and practice have advanced
hand in hand, by the investigation of the constituent
materials of concrete. In the West, no...
Thousands of children and adults suffer from fine motor skill deficits due to developmental disabilities or brain trauma. In order to acquire or reclaim these precision motor movements, occupational therapists work closely with each patient to develop the muscle memory required for completing tasks such as handwriting or drawing. Although...
The ultimate goal of large-scale design organizations are mainly to reduce costs and improve reliability and performance of systems while assessing how much risk (cost, schedule, scope) they can take and still remain competitive. To achieve this goal they need to develop tools to reach the most preferred design product...
We hypothesize that the extraordinary maneuverability and efficiency of bats in flight are in part due to the compliant nature of their wing structures. We utilize the parameters of bat bones measured by biologists to create a biologically inspired model of a flapping system consisting of a rotating hub actuator...
Modern complex mechanical systems have evolved to a point of incredible complexity. Many now operate with significant assistance from automated response functions, and some operate without human operators at all. These increasingly complex systems have also become more expensive and more ambitions in mission, bringing about higher risk to both...
For safety critical complex systems, reliability and risk analysis are important design steps. Implementing these analyzes early in the design stage can reduce costs associated with redesign and provide important information on design viability. In the past several years, various research methods have been presented in the design community to...
Ocean wave energy is a new and developing field of renewable energy with great potential. The energy contained in one meter of an average wave off the coast of Newport Oregon could supply dozens of homes with electricity. However, ocean waves are usually quite irregular which leads to large bursts...
An experimental and numerical study of absorption of ammonia vapor bubbles into a constrained thin film of ammonia-water solution is presented in the context of a potential reduction in size of a heat-actuated heat pump component. A large-aspect-ratio channel with a depth of 600 µm restricts the thickness of the...
The pressure drop of convective boiling flow may be reduced by extracting vapor locally since the entire generated vapor does not have to travel through the entire channel length. In this study, the theoretical model was developed to simulate a convective boiling flow through a fractal-like branching microchannel network with...
The increasing level of complexity in systems creates a growing challenge
for engineers to design safe and reliable systems. The growing complexity can
lead to possible moments when situations occur that were unanticipated or were
not known that they could occur by designers and leave the system in an
undesirable...
This study investigates the hydrodynamic characteristics of droplet impinging on heated surfaces using High Speed High Resolution (HSHR) imaging and evaluates the effect of surface temperature and using water and a nanofluid on a polished and a nano-structured surface. Three types of surfaces are used in the
study: polished silicon,...
Coordination in large multiagent systems in order to achieve a system level goal is a critical challenge. Given the agents' intention to cooperate, there is no guarantee that the agent actions will lead to good system objective especially when the system becomes large. One of the primary difficulties in such...
Multiphase flow dynamics are important in many naval and turbomachinery applications, where bubble interaction with low pressure, vortical structures can lead to undesirable cavitation effects. To better understand the underlying phenomena, a multiscale numerical framework is developed to simulate bubble laden flow in dynamic hydro propulsion systems. Several subproblems in...
Business and recreation in the modern day world often include air travel as their
cornerstone. Travelers who are disabled and wheelchair bound have to undergo a
transfer process to board and deplane a commercial aircraft. This transfer process is
typically done manually, with agents physically lifting the passenger who is...
It is hypothesized that extracting the vapor from two-phase flow in a microchannel will result in a lowered pressure drop required to drive the flow. The goal of this thesis is to construct an experimental device that will test this hypothesis by comparing a number of phase separating test conditions...
This study sought to ascertain the degree to which the night sky of Corvallis is affected by light pollution by determining the limiting visual magnitude. Defined as the brightness of the dimmest star that can be seen with the averted naked eye, the limiting visual magnitude establishes a quantitative standard...
The marathon is well noted for the extreme stress it applies to the body and mind. The
physiological aspects of marathon training were investigated and examined for someone
unfamiliar with the field. Several training programs were investigated within a
framework provided by the popular Daniels' Running Formula. By the Formula's...
An actuated, bipedal model is developed to investigate lateral plane locomotion dynamics and stability on inclines. Both the point mass case and rigid body case are considered. Variations in the force-free leg length are determined via inverse dynamics to explicitly and implicitly match prescribed lateral and fore-aft force profiles, respectively....
Recently, fiber-reinforced plastics (FRP lamina) have
been applied to glued-laminated (glulam) timber for the
purpose of improving bending strength and stiffness.
Initially, full length reinforcement using FRP lamina was
developed. However, the cost of FRP lamina is a significant
portion of the total cost of reinforced glulam. Therefore,
it is...
This thesis explores the implementation of learning based control with predictive cruise control and the potential this technology has for increasing fuel efficiency while keeping on a well maintained schedule for commercial trucks. Traditional cruise control is wasteful when maintaining a constant velocity over rolling hills. Predictive cruise control is...
Many animals detect prey or enhance their locomotion with information from hair-like receptors that are activated by local fluid flows. The utility of biological hair receptors has motivated the design of artificial hair sensors (AHS) for flow control applications where aerodynamic or hydrodynamic forces play a significant role in the...
Micro scale systems are being utilized in a wide variety of chemical, biological and heat exchanger applications, but suffer from the development of vapor bubbles inside the microchannels due to convective boiling, leading to decreases in system performance. In this work, a simulation-based control strategy is employed to eliminate flow...
The use of autonomous robots in complex exploration tasks is rapidly increasing. Indeed, robots can provide speed and cost effectiveness in many tasks, as well as allow operation in environments that are hostile to humans. In this dissertation we: 1) provide two adaptive navigation algorithms; 2) develop a coordination mechanism;...
In granular or fibrous materials, in which the dimensions of the internal
structure can be of the same order of magnitude as major flaws or holes, classical
elasticity theory does not consistently provide accurate models of the large stress
gradients that may develop. With the incorporation of additional rotational degrees...
This thesis addresses Micro Aerial Vehicle (MAV) control by leveraging learning based techniques to improve robustness of the control system. Applying classical control methods to MAVs is a difficult process due to the complexity of the control laws with fast and highly non-linear dynamics. These methods are mostly based on...
Research in the miniaturization of thermomechanical systems in recent years has proven to be both rewarding and challenging. Micro-scale devices have tremendous technological potential but come with a new set of design problems. One such problem is energy storage. Heat actuated systems, driven primarily by thermal energy, take advantage of...
Sprawled-posture insects exhibit a remarkable ability to rapidly run in a stable manner
over complex terrain, a feat that has yet to be equaled by man-made legged robots.
Recent experimental results suggest that these insects may employ a hierarchical
control structure, in which locomotion performance emerges from a combination of...
Many engineering devices and propulsion systems suffer from undesirable effects of cavitation; such as degradation in the efficiency of pumps and turbines, generation of noise and vibration on ship propeller, increased drag and erosion of propeller blade, etc.
In spite of decades of research on this problem, detailed study of...
Quadrotors are unique among Micro Aerial Vehicles in providing excellent maneuverability (as opposed to winged flight),while maintaing a simple mechanical construction (as opposed to helicopters). This mechanical simplicity comes at a cost of increased controller complexity. Quadrotors are inherently unstable, in the sense that they are essentially unflyable by a...
A collection of short stories in the style of flash fiction. The themes of the stories include relationships, legality, and friendship. The stories are connect by themes, cross self-referencing, repetition, fragmentation, and characters. The main unifying feature is the characterization of the narrator through his response and commentary. The styles...
This research studied the effects of changing from a traditional manufacturing
system to a cell manufacturing system in a value-added wood products company.
Discrete event simulation was used to describe the current system and the proposed
new systems. Parts were separated into part families that shared similar processing
requirements. From...
Computing agents require state information to make coherent and useful decisions. A state representation is a numerical translation of the environment and conditions that are pertinent factors in an agent's decision making. Although many representations, when paired with clever learning algorithms, are able to coordinate and capture prey in specific...
Low Reynolds number airfoils have become of interest recently for applications on Micro-air Vehicles (MAVs). Airfoils at low Reynolds numbers and high angles of attack are known to be unstable due to low lift to drag ratios. This study investigates the effect of a movable leading edge flap on the...
The world is currently using an unsustainable system of meeting its transportation
needs with oil. This system is taking a toll on the world environment and on global politics.
The physical availability of oil is the system’s most immediate problem and will most likely
bring about a transition away from...
Ocean Wave Energy Converters (WECs) operating on the water surface are subject to storms and other extreme events. In particular, high and steep waves, especially breaking waves, are likely the most dangerous to WECs. A method for quantifying the breaking severity of waves is presented and applied to wave data...
Aerodynamic improvements in automotive racing can have a significant effect
on vehicle performance. Recent developments in Formula SAE (Society of
Automotive Engineers) have included the design and implementation of aerodynamic
devices such as inverted wings and undertrays to improve performance. In this work
the literature of undertray technology is presented...
Since the Industrial Revolution, automated systems have increasingly become a part of everyday life. Automated systems range in scale and scope from simple assists to complete robotic replacements. Inexpensive integrated circuits, sensors and microprocessors have allowed automated systems to become smaller, cheaper and more prevalent. Identifying appropriate opportunities for automation,...
The optimal design technique for minimum power loss in
traction drive continuously variable transmissions is
developed. The mathematical model is developed to
evaluate the traction force and torque in traction drive
contact. Kinematic analysis of general traction drive
contact is conducted to find the best configuration for
minimum power loss....
The substantial wave energy resource of the US Pacific Northwest (i.e. off the coasts of Washington, Oregon and N. California) is assessed and characterized. Archived spectral records from ten wave measurement buoys, operated and maintained by the National Data Buoy Center and the Coastal Data Information Program, form the basis...
Numerical modeling of methane-steam reforming is performed in a micro/mini-channel with heat input through catalytic channel walls. The low-Mach number, variable density Navier-Stokes equations together with multicomponent reactions are solved using a parallel numerical framework. Methane-steam reforming is modeled by three reduced-order reactions occurring on the reactor walls. The surface...
Steam-methane reforming is a well understood industrial process used for generating hydrogen and synthesis gas. The reaction is generally carried out with residence times on the order of one second. By performing this reaction at microscales it is possible to take advantage of increased heat transfer rates and low diffusion...
Currently, the temporal arc distribution across the ingot during the vacuum arc remelting (VAR) process is not a known or monitored parameter. It is has previously been shown that arcs can spatially constrict during VAR, and this constriction can lead to undesired defects in the material. Additionally, correct accounting for...
Novel fluidic devices that utilize an array of microchannels to achieve their designed purpose are discussed. Examples of devices include: fuel reforming using Microreactors, chip cooling using microchannel heat sinks, and microchannel devices used for biological applications. The devices that have directly contributed to this research include: a microchannel water...
Customer requirements and engineering specifications will influence the direction of the design in any product, so it is crucial to make the requirements as stable as possible so quality designs can be produced on time within a budget. It would be optimal for requirements and specifications to remain constant but...
Over the last few decades, the methods and tools through which humans collaborate, share knowledge and generally communicate have been advancing at a rapid pace. Thanks mostly to advances in broadband internet, cheap data storage and fast microprocessors, humans now have the ability to work together in ways that even...
Wave dispersion and fracture are phenomena that involve. mechanisms triggered at the scale of a material's internal structure. Experiments were performed with a candidate material to judge the hypothesis that wave dispersion measurements can be used to nondestructively predict fracture strength. Wood-based particleboard was chosen as the candidate material because...