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....
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...
PDMS membrane-based microvalves are becoming increasingly more important for the control of fluid flow within MECS applications such as microreactors used to synthesize nanoparticles and biological macromolecules. The motivation for pursuing PDMS membrane-based microvalves is for implementing a plug flow microreactor to simulate slug flow yielding a narrower residence time...
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...
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)...
This research proposes a Human Fallibility Identification and Remediation Methodology (HFIRM) that supports the systematic identification and remediation of potential human errors. The objective of this research was to develop and test a prototype framework that supports the practical application of human factors knowledge to the analysis and design of...
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...
Accurate freeway travel time estimation is of increasing importance for the travelers’ information and route guidance system. A non-parametric statistical methodology known as regression trees is deployed in this research for dynamically and accurately estimating freeway travel times for the I5-I205 loop in the Portland Metro area of Oregon using...
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...
Diffusion bonding cycle times can be a large cost factor in the production of metal microchannel devices. The challenge is to significantly minimize this cost by reducing the bonding cycle time through rapid and uniform heating and cooling within the bonding process. Heating rates in diffusion bonding processes are typically...
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...
Recent efforts show that microchannel technologies have much to offer the field of nanomanufacturing: the structuring of matter on the order of one billionth of a meter. During the synthesis of nanomaterials, microchannel reactors take advantage of large surface-to-volume ratios to accelerate heat and mass transport. This accelerated transport allows...
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...
Micro Powder injection molding (μPIM) is a cost-effective technique for
producing small, complex, precision parts in high volumes from ceramic and
metal nanoparticles. This study focuses on research conducted on fabrication of
Micro Ceramic Arrays (MCAs) parts using μPIM. MCAs are widely used as the
major components and design features...
This thesis describes a Systemic Vulnerability Identification and Remediation (SVIR) methodology that identifies human fallibilities and errors in complex technical processes, and recommends remediations for the errors, based on human factors principles and guidelines. The objectives of the research described in the thesis are the development of the methodology and...
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...
Oregon Department of Transportation (ODOT) Fleet Services manages a fleet that in 2008 included approximately 5,000 pieces of active equipment worth $340–$390 million. Every biennium, a fixed budget is available to replace a certain amount of this equipment. This research evaluated various measures for establishing equipment replacement priorities.
A model...
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...
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...
In container terminals, the efficiency of loading operations in a container yard highly
depends on the productivity of yard cranes. In loading operation, yard cranes have to
pick-up the containers which are stacked in the yard-bays to satisfy the work schedule
requirement of quay crane, the equipment for loading and...
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...
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....
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...