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...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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,...
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,...
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...
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...
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...
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...
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 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;...
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...
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...
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...
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...
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...
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...
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...
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...
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...