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Articles 1 - 30 of 88
Full-Text Articles in Engineering
Real-Time Length Sensing Of Braided Pneumatic Actuator Using Ir Time-Of-Flight Sensor, Luon B. Chung
Real-Time Length Sensing Of Braided Pneumatic Actuator Using Ir Time-Of-Flight Sensor, Luon B. Chung
Dissertations and Theses
Braided Pneumatic Actuators (BPAs) are used widely in robotics as artificial muscles because of their similar characteristics to biological muscles. When a BPA is pressurized, it expands in the radial direction and contracts in the longitudinal direction. The contraction generates a pulling force that is dependent on the input pressure and BPA length. Biological muscle also behaves in the same way where a pulling force is generated on a contraction. To control BPAs on a robot, the real-time pressure and length measurements are necessary. In this dissertation, I present a new method to measure length of BPAs in real-time using …
Developing And Testing Low-Cost Air Cleaners For Safer Spaces During Wildfires, Brett William Stinson
Developing And Testing Low-Cost Air Cleaners For Safer Spaces During Wildfires, Brett William Stinson
Dissertations and Theses
Air cleaning reduces indoor exposure to fine particulate matter (PM2.5) during wildfire events. However, resource and cost restraints may limit access to air cleaning during such an event, as both commercial devices and the high-rated MERV filters that homemade assemblies typically rely upon tend to be expensive and in short supply. With these barriers in mind, we sought to develop and evaluate the potential for air cleaners that use common household fabrics as filtration media. Evaluated designs use a box fan to move air across fabric filters; box fans are inexpensive and readily available to many households. Ultimately, …
Consumer 3d Printing For Remote Control Aircraft Wings: Development Of Novel Wingbox Structure, Ian Clark
Consumer 3d Printing For Remote Control Aircraft Wings: Development Of Novel Wingbox Structure, Ian Clark
University Honors Theses
Remote control aircraft construction and can be a very expensive and time-consuming hobby. With 3D printer consumer adoption rates skyrocketing, there is a gap between demand for RC aircraft and suitable well-designed models available to creators and hobbyists. By creating and testing two iterations of wingbox geometries, this research aims to help close that gap by producing an easily printable wing structure. While there are improvements that can be made on this work, this research has been effective in generating a novel wingbox structure for FFF 3D printing that has distinct advantages over other designs currently available.
Surface Roughness Prediction In End Milling Processes Considering The Vibration Of The Cutting Tool, Yubin Lee
Surface Roughness Prediction In End Milling Processes Considering The Vibration Of The Cutting Tool, Yubin Lee
Dissertations and Theses
Purpose: Machining is a manufacturing process for making the desired design with dimensional tolerance and surface roughness. Despite the development of engineering technology, predicting machined surface roughness is still challenging since there are various factors, such as material properties, tool material properties, the rigidity of the machine tool, and the use of coolant. In particular, tool vibration is the most critical factor since it makes it challenging to obtain the desired quality of the machined product by unintentionally making a tool move. Therefore, surface finish was explored in this study, considering cutting tool vibration under various axial depth-of-cuts and feed …
Comparing The Performance Of Different Machine Learning Models In The Evaluation Of Solder Joint Fatigue Life Under Thermal Cycling, Jason Scott Ross
Comparing The Performance Of Different Machine Learning Models In The Evaluation Of Solder Joint Fatigue Life Under Thermal Cycling, Jason Scott Ross
Dissertations and Theses
Predicting the reliability of board-level solder joints is a challenging process for the designer because the fatigue life of solder is influenced by a large variety of design parameters and many nonlinear, coupled phenomena. Machine learning has shown promise as a way of predicting the fatigue life of board-level solder joints. In the present work, the performance of various machine learning models to predict the fatigue life of board-level solder joints is discussed. Experimental data from many different solder joint thermal fatigue tests are used to train the different machine learning models. A web-based database for storing, sharing, and uploading …
Effectiveness Of Air Pollution Mitigation Systems: Transport, Transformation, And Control Of Ozone In The Indoor Environment, Pradeep Ramasubramanian
Effectiveness Of Air Pollution Mitigation Systems: Transport, Transformation, And Control Of Ozone In The Indoor Environment, Pradeep Ramasubramanian
Dissertations and Theses
Buildings are critical environments governing our collective exposure to air pollution and energy consumption. While there exist concerns regarding increases in building energy consumption due to indoor air interventions, improvements to the quality of air indoors can improve health, comfort, and productivity. Air cleaning technologies that can improve indoor air quality with minimal energy consumption have become ever more important. These technologies are utilized at various scales; from passive removal of pollutants in the air entering the indoor environment to active cleaning of air within the breathing zone. To better understand the effectiveness of active and passive ozone mitigation technologies …
Quantification Of Reynolds Shear Stress Wave-Phase Dependence In Fixed-Bottom Offshore Wind Turbine Via Quadrant Analysis, Cerrina Mouchref, Bianca Viggiano, RaúL BayoáN Cal, Ondrej FerčÁK
Quantification Of Reynolds Shear Stress Wave-Phase Dependence In Fixed-Bottom Offshore Wind Turbine Via Quadrant Analysis, Cerrina Mouchref, Bianca Viggiano, RaúL BayoáN Cal, Ondrej FerčÁK
University Honors Theses
As the need for a reliable renewable energy supply is increasing, many have looked to offshore wind because they hold more potential for power production than onshore wind. Interests in expanding offshore wind energy has brought along many challenges when it comes to understanding the complex dynamics experienced offshore, including the relationship between the wind-turbine generated wakes and ocean waves. This experimental study characterizes the relationship between Reynolds shear stress and the phase of surface waves above the air-sea interface in the wind-turbine wake region. The experimental setup combines a wave tank, wind tunnel, and a fixed-bottom wind turbine. Particle …
The Evaluation Of Performance Of Spindle Connector And Its Finite Element Analysis, Suhyun Lee
The Evaluation Of Performance Of Spindle Connector And Its Finite Element Analysis, Suhyun Lee
Dissertations and Theses
The rapid development of machining technology and reliable high-speed machining systems has led to a fast operation of machines. However, machining machines cannot still meet modern requirements in terms of the quality of parts, the machine components, and the life of the tools. The major components of the machining system are machine tools, the spindle interfaces (the contact between the spindle and the tool holder), and tools. The choice of the spindle connector is the main decision, as this defines the limitation of the metal cutting efficiency and considerably influences the deformation of the machine tool. Therefore, it is very …
The Effect Of Viscosity On The Puddle Dynamics In Low Gravity Environment, Taif Hamed Saleh Al Juboori
The Effect Of Viscosity On The Puddle Dynamics In Low Gravity Environment, Taif Hamed Saleh Al Juboori
Dissertations and Theses
Enormous liquid puddles are observed to jump spontaneously from non-wetting substrates when exposed to the nearly step-reduction in body force common to drop tower test facilities. The phenomenon is similar to the second half of terrestrial drop bounce experiments except that (1) the initial static equilibrium configuration satisfies the static contact angle condition, (2) the initial height of the puddle is limited to the capillary height, and (3), for drop tower test durations on the order of seconds, puddle volumes can be over 104 times larger in mass (volume). The passive puddle jump mechanism provides a no-moving-parts deployment method …
Building A Biomechanical Model Of A Rat Forelimb, Joshua Nathaniel Eric Mak
Building A Biomechanical Model Of A Rat Forelimb, Joshua Nathaniel Eric Mak
Dissertations and Theses
This paper presents a biomechanical model of the rat forelimb to test theories of determining viscoelastic muscle parameters. Several biomechanical models of rat hindlimbs have been developed and have explored the effects of multi-muscle control during locomotion. The forelimb model uses two ball-and-socket joints to model clavicle and scapula movement. A third ball-and-socket joint is used at the shoulder and two hinge joints are used at the elbow and wrist. Scapula motion is further constrained by muscle and spring elements. Each forelimb has 11 degrees of freedom, and 23 Hill-type muscles. The model has been created in Animatlab, which includes …
Fixed Bottom Wind Turbine Wave-Wake Interaction, Ondrej Fercak
Fixed Bottom Wind Turbine Wave-Wake Interaction, Ondrej Fercak
Dissertations and Theses
The interest and benefits of offshore wind energy has also brought along legitimate design challenges for engineers. Most notably, the complex interaction between wind and turbine is further complicated by the addition of dynamic ocean waves. This dynamic coupling between wind, wave, and turbine is not fully understood. Even small improvements in wind turbine performance are welcome, so characterizing a fundamental dynamic in offshore energy is necessary to optimize design. Experimentation and simulation have been used to characterize inflow and turbine wakes and separately, wind-wave interactions. But only simulations have just begun to look at the wind, wave, and turbine …
Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong
Optimization Of 3d Printed Mold Performance For Injection Molding Via Hollow Infill Patterns, Alan Fong
University Honors Theses
The applicability of hollow infill patterns has been explored for its applications in making 3D printed polymer-based injection molds in the additive manufacturing industry. Hollow infill patterns offer a significant reduction in material costs as well as the opportunity for reducing the cooling times via pumping a coolant fluid through the hollow cavity in a similar fashion to traditional conformal cooling channels. A 3D Jacks Support Hollow mold model was determined to be the best performing design. FEA analysis was conducted to determine the maximum reduction in internal volume (percentage of material saved) that could be achieved without exceeding the …
Entrainment Processes For A Jet In Cross-Flow: The Quantification Of Turbulent Contributions And Their Importance On Accurate Modeling, Graham Asher Freedland
Entrainment Processes For A Jet In Cross-Flow: The Quantification Of Turbulent Contributions And Their Importance On Accurate Modeling, Graham Asher Freedland
Dissertations and Theses
A jet in cross flow (JICF) is examined experimentally by injecting a stream of air into crossing fluid with an aim into quantifying entrainment process and downstream evolution. The behavior of JICF is important to fields ranging from turbine-blade cooling to smokestack pollution and volcanic eruption dynamics. Existing simplified volcanic plume models are tested; most importantly, the near-field contributions of complex interconnected vortex systems, which present significant uncertainties because they assume negligible turbulence. While jets in irrotational cross-flow have been investigated, this analysis has focused on the interaction between a turbulent jet in low and highly turbulent cross-flow created by …
Modeling Airflows And Voc Source Strengths For An Occupied School, Brett Stinson
Modeling Airflows And Voc Source Strengths For An Occupied School, Brett Stinson
University Honors Theses
Volatile organic compounds (VOCs) are a group of air pollutants that can adversely impact human health, engage in chemistry indoors, and meaningfully degrade indoor and outdoor urban air quality. While extensive research with regard to VOC emission rates from indoor sources has been conducted, it was not until recently that this work began to focus on characterizing emissions from humans and human activity in depth. As buildings are constructed to be increasingly airtight, and the materials utilized are chosen to reduce VOC emissions, it follows that human contributions are poised to become increasingly important indoor sources of VOCs. Utilizing data …
Indoor Air Quality Impacts Of A Woodstove Exchange Program In Washington County, Oregon, Matthew Forrest Survilo
Indoor Air Quality Impacts Of A Woodstove Exchange Program In Washington County, Oregon, Matthew Forrest Survilo
Dissertations and Theses
More than six million people in the United States use wood stoves as their primary heat source. Wood stoves emit air pollutants that may impact health, e.g., wood combustion products are associated with premature death and aggravation of pulmonary and cardiovascular conditions. There are few studies investigating the efficacy of wood stove exchange programs (WSEPs) as a method to improve indoor air quality (IAQ). In partnership with Washington County Department of Health and Human Services we conducted an air quality study to measure the impact of a WSEP on indoor and neighborhood levels of wood combustion products. Twenty households engaged …
Dynamic Effects Of Inertial Particles On The Wake Recovery Of A Model Wind Turbine, Sarah E. Smith
Dynamic Effects Of Inertial Particles On The Wake Recovery Of A Model Wind Turbine, Sarah E. Smith
Dissertations and Theses
Impacting particles such as rain, dust, and other debris can have devastating structural effects on wind turbines, but little is known about the interaction of such debris within turbine wakes. This study aims to characterize behavior of inertial particles within the turbulent wake of a wind turbine and relative effects on wake recovery. Here a model wind turbine is subjected to varied two-phase inflow conditions, with wind as the carrier fluid (Reλ = 49 - 88) and polydisperse water droplets (26 to 45µm in diameter) at varied concentrations (Φv=0.24 x 10-5 - 1.3 …
Droplet Ejections During Wet Lab Operations Aboard Spacecraft, Caleb Cushman Turner
Droplet Ejections During Wet Lab Operations Aboard Spacecraft, Caleb Cushman Turner
Dissertations and Theses
The breakup and rupture of liquid bridges, thin films, bubbles, droplets, rivulets, and jets can produce satellite droplets that are subsequently ejected into their surrounding environment. For example, when any solid object is withdrawn from a liquid bath, the formation of an ever-thinning columnar liquid bridge eventually ruptures along the axis of the bridge. When rupture occurs under typical pipetting conditions the dynamics governing the rupture almost always produce at a minimum a satellite droplet. When these droplets occur they are often too small and too fast to be observed by the human eye. In a terrestrial environment they are …
A Numerical Investigation Of Microgravity Evaporation, Daniel Peter Ringle
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 …
Characterization Of Inertial Particles In The Turbulent Wake Of A Porous Disk, Kristin Nichole Travis
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 [Φv ∈ (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 …
Passive Separation Of Binary Fluid Mixtures In Microchannels Using Lattice Boltzmann Method, Mohanad Kamil Radhi
Passive Separation Of Binary Fluid Mixtures In Microchannels Using Lattice Boltzmann Method, Mohanad Kamil Radhi
Dissertations and Theses
Fluid mixtures in real life exist in two forms: miscible and immiscible. Separation of these mixtures using chemical agents or thermal energy has both environmental and economic disadvantages. The high cost and the environmental damage caused by the traditional separation techniques have stimulated both academia and industry to seek alternatives. The emergence of microfluidics offers robust solutions for a broad span of transport problems due to the high surface to volume ratio and reduced length scales. Particularly, the separation efficiency increases significantly due to the aforementioned feature. However, there is still a pressing need of passive separations for the sake …
Tracking Center Of Mass With Limited Inertial Measurement Units, Connor Nathaniel Morrow
Tracking Center Of Mass With Limited Inertial Measurement Units, Connor Nathaniel Morrow
Dissertations and Theses
Wearable motion tracking systems pose an opportunity to study and correct human balance and posture during movement. Currently, these observations are either being conducted in laboratories with the use of camera systems and markers placed on the body, or through the use of suits containing large numbers (15-20) of inertial measurement units. However, to aid with rehabilitation of individuals with impaired balance, there needs to be an option to collect these observations outside of clinics and without incurring much cost from the user. I have focused on three inertial measurement units, one placed on each shank and one placed on …
Non-Contact Distillation, Rawand Muzafar Rasheed
Non-Contact Distillation, Rawand Muzafar Rasheed
Dissertations and Theses
Leidenfrost phenomenon has been studied extensively for its role in applications ranging from nuclear reactor cooling, to metals manufacturing, combustion, and other fields. Herein, Leidenfrost phenomenon is pursued towards non-contact distillation processes with hopes of reducing or even eliminating contaminant fouling. In particular, the microgravity environment of a drop tower is exploited to demonstrate the facility with which droplets achieve and sustain the Leidenfrost state. Dynamic Leidenfrost impacts in microgravity are presented for impacts on hydrophilic and superhydrophobic planar substrates, macro-pillar arrays, confined passageways, and others. Nearly ideal elastic non-contact impacts and droplet oscillation modes are observed. Dynamic Leidenfrost impacts …
Design Of A Canine Inspired Quadruped Robot As A Platform For Synthetic Neural Network Control, Cody Warren Scharzenberger
Design Of A Canine Inspired Quadruped Robot As A Platform For Synthetic Neural Network Control, Cody Warren Scharzenberger
Dissertations and Theses
Legged locomotion is a feat ubiquitous throughout the animal kingdom, but modern robots still fall far short of similar achievements. This paper presents the design of a canine-inspired quadruped robot named DoggyDeux as a platform for synthetic neural network (SNN) research that may be one avenue for robots to attain animal-like agility and adaptability. DoggyDeux features a fully 3D printed frame, 24 braided pneumatic actuators (BPAs) that drive four 3-DOF limbs in antagonistic extensor-flexor pairs, and an electrical system that allows it to respond to commands from a SNN comprised of central pattern generators (CPGs). Compared to the previous version …
Characterizing Tilt Effects On Wind Plants, Ryan Scott
Characterizing Tilt Effects On Wind Plants, Ryan Scott
Dissertations and Theses
Tilting the nacelle of a wind turbine modifies entrainment into the wind plant and impacts total efficiency. Extreme angles can produce flying and crashing wakes where the wake either disrupts entertainment from the undisturbed flow above or is decimated on the ground. The effect of tilt angle on downstream wake behavior was investigated in a series of wind tunnel experiments. Scale model turbines with a hub height and diameter of 12 cm were arranged in a Cartesian array comprised of four rows of three turbines each. Nacelle tilt was varied in the third row from -15° to 15° in chosen …
Infinite Photovoltaic Solar Arrays: Considering Flux Of Momentum And Heat Transfer, Andrew D. S. Glick
Infinite Photovoltaic Solar Arrays: Considering Flux Of Momentum And Heat Transfer, Andrew D. S. Glick
Dissertations and Theses
Large scale solar farms supply an increasing amount of the worlds electricity supply. However, in order to reach cost parity with fossil fuels, further reductions are necessary. Towards this end, photovoltaic (PV) panel cooling becomes increasingly important; high temperatures both decrease efficiency and panel lifetime. To better understand, characterize, and exploit the natural convective cooling of utility scale solar farms, a model solar farm was created. Using both thermal measurements and particle image velocimetry to characterize heat transfer and velocity fields, wind tunnel experiments were conducted using the model solar farm. Three parameters were examined for their effect on heat …
Fatigue Characteristics Of New Eco Series Aluminum 7175 Alloy, Chinh Q.L. Vu
Fatigue Characteristics Of New Eco Series Aluminum 7175 Alloy, Chinh Q.L. Vu
Dissertations and Theses
In this dissertation, the fatigue characteristics of three newly developed experimental compositions for aluminum 7175, with improved mechanical strength, that uses magnesium-calcium alloy instead of pure magnesium are studied.
Specimens of each variant were fabricated and subjected to fatigue life testing, fatigue life data analysis, and observation of their fracture characteristics through optical microscopy and scanning electron microscopy (SEM), and metallography to study their grains and surface characteristics.
Fatigue life testing shows all three variants have a fatigue strength that is approaching approximately 200 MPa. ECO7175v3 is shown to have the highest fatigue strength of approximately 220 MPa at 5x10 …
A Study Of Thermal Energy Storage Of Phase Change Materials: Thermophysical Properties And Numerical Simulations, Kyung-Eun Min
A Study Of Thermal Energy Storage Of Phase Change Materials: Thermophysical Properties And Numerical Simulations, Kyung-Eun Min
Dissertations and Theses
A Thermal Energy Storage (TES) system is meant for holding thermal energy in the form of hot or cold materials for later utilization. A TES system is an important technological system in providing energy savings as well as efficient and optimum energy use. The main types of a TES system are sensible heat and latent heat. A latent heat storage is a very efficient method for storing or releasing thermal energy due to its high energy storage density at constant temperatures, and a latent heat storage material can store 5-14 times more heat per unit volume than a sensible heat …
Thermally (Un-) Stratified Wind Plants: Stochastic And Data-Driven Reduced Order Descriptions/Modeling, Naseem Kamil Ali
Thermally (Un-) Stratified Wind Plants: Stochastic And Data-Driven Reduced Order Descriptions/Modeling, Naseem Kamil Ali
Dissertations and Theses
Wind energy is one of the significant sources of renewable energy, yet a number of challenges preclude optimal operation of wind plants. Research is warranted in order to minimize the power losses and improve the productivity of wind plants. Here, a framework combining turbulence theory and data mining techniques is built to elucidate physics and mechanisms driving the energy extraction of the wind plants under a number of atmospheric/operating conditions. The performance of wind turbines is subjected to adverse effects caused by wake interactions. Therefore, it is crucial to understand wake-to-wake interactions as well as wake-to-atmospheric boundary layer interactions. Experimental …
Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian
Ozone-Surface Exchange And Transport And Transformation Near Ventilation Air Supply, Pradeep Ramasubramanian
Dissertations and Theses
Ozone in indoor environments can pose a health risk to human occupants; around half of exposure to this pollutant occurs inside buildings. One approach to reducing indoor O3 levels is to mitigate O3 as it enters a building via outdoor air ventilation supply. Often, mechanical systems that introduce outdoor air into buildings are placed on building rooftops. At the urban scale, greenery has been shown to reduce levels of some harmful pollutants, including ozone and cities like Portland, OR, are mandating green roofs be built on large commercial buildings to increase urban green surfaces. We investigate if rooftop …