As climate change contributes to larger and more severe wildfires in California, areas of fire refugia – considered unburned and low-severity burn patches – are playing an increasingly important role in sustaining ecosystem resilience, maintaining biodiversity, and supporting post-disturbance recovery. At the same time, climate refugia – which are areas...
Prototyping is a crucial step in product design and development, but it is also known as the highest sunk cost. The top 20 Research and Development (R&D) department spends 142 billion dollars, yet 40 to 46 percent of this money goes into developing products that cannot even make to the...
The first part of the dissertation chronicles irrigation technology changes to progressively improve water application efficiency, water use efficiency, irrigation water productivity and crop production. Technological innovation in irrigation, from 6000 BC to present, has been driven by an unchanging need to provide support for growing populations. The first irrigation...
Growing populations and industrialization rates across the world are leading to increased food and energy demand. The challenge of meeting this demand while also mitigating climate change impacts serves as a driving force for the development of renewable energies technologies. This study focuses on the role of Agrivoltaic systems in...
Structural Health Monitoring (SHM) is known as the process of implementation of damage detection and characterization strategy. The method is widely used in modern critical equipment to minimize the risk of failures. While a significant effort has been devoted by researchers for the detection of faults in situations including periodic...
Unmanned Aerial System (UAS) technology is a rapidly developing technological marketspace. This thesis focuses on micro, tethered, coaxial UASs and the development of an electrically-tethered observation platform (ETOP). The thesis details the current status of the technology as well as current products on the market. Stability considerations, critical when adding...
Tropical peatlands play an important role in global climate system by storing an immense of carbon that had been accumulated over thousands of years. Peatlands provide another important ecosystem service by regulating the hydrology. It is believed that peatlands act like a giant sponge by absorbing substantial amounts of water...
Lower atmospheric flux measurements are a difficult subset of atmospheric data to accurately collect. The interplay of cost, precision, specialty, resolution and repeatability compound an already difficult experimental problem. In response to this, a new, novel instrumentation approach to measuring within the atmospheric boundary layer (ABL) is introduced.
The combination...
Designing a carbon fiber chassis for the Global Formula Race car has historically proven to be both time intensive and difficult. The goal of this thesis is to improve the design process for testing Global Formula Racing team's composite chassis sandwich panels. Consideration was taken regarding Formula SAE rules, and...
Micro air vehicles (MAV's) and small unmanned aerial vehicles (SUAV) are remotely piloted or autonomous aircraft with a take-off mass range between 50 g and few kilograms. These vehicles, as well as natural fliers such as bats and insects, utilize a variety of elastic wing structures including thin membranes. Over...
Many different models and mechanisms of water imbibition into soil have been described in the literature. Theoretical equations based on those models exist to predict how water will flow in porous media. These models can be useful, but have their weaknesses. Research on imbibition and infiltration into soils has mostly...
Geologic CO₂ sequestration is a climate change mitigation strategy that prevents CO₂ emissions to the atmosphere by capturing CO₂ gasses from large point source emissions streams and then pressurizing and pumping the supercritical-state CO₂ into underground geologic storage reservoirs. Once underground, CO₂ is prevented from buoyant migration to the surface...
The objective of this project is to demonstrate the feasibility fiber-reinforced turbine components through a design and manufacturing study. The motivation for using composites is to reduce weight and simplify manufacturing especially at high production volumes. In addition, natural fiber composites are implemented for applicable components to reduce environmental impact....
Groundwater resources have become seriously threatened
due to improper use by industrial, municipal, and even public
sectors. Widespread contamination of aquifer systems has
jeopardized human health and the environment and methods for
restoring these systems are needed. Biological and chemical
in situ remediation, where contaminants are degraded within
the natural...
Among the many safety hazards facing chainsaw operators, the phenomenon known as kickback is the most dangerous. Kickback occurs when the chain at the tip of the chainsaw is caused to stop abruptly, and transfers the energy of the cutting chain to motion of the saw. The saw will rotate...
Small commercial and non-commercial animal enterprises (SCAEs) raise a few
beef cows, horses, pigs, sheep, poultry, and other animals on a few acres. These
enterprises are often located in suburban areas of watersheds and show potential for
degrading water quality through to increased bacterial, nitrogen, and phosphorus
concentrations. SCAEs implement...
The Environmental Conditioning System (ECS) was designed to evaluate the
water sensitivity of asphalt concrete mixtures. The ECS subjects asphalt concrete specimens to a series of conditioning cycles including water flow, elevated and/or lowered temperature, and repeated axial loading. The purpose of this research was to: (1) evaluate the ECS...
Dry land agriculture using summer fallow is a common crop production
practice in the Columbia Plateau region of eastern Oregon. Farmed-over level
terraces are used to control surface water runoff and soil erosion. More than
70 percent of the average annual precipitation around Pendleton, Oregon (350 -
400 mm) falls...
Furrow irrigation is the dominant practice for irrigating row crops in the western Treasure Valley region near Ontario, Oregon. Though improvements have been made in management practices over the years, excessive runoff and deep percolation are still important problems contributing to surface water and groundwater degradation. Field observations were made...
Understanding the processes involved in the transport of dissolved gas plumes in groundwater aquifers is essential for comprehending the effect that these transport processes can have on site characterization and remedial design applications. Previous laboratory and field studies have indicated that dissolved gas transport in groundwater can be greatly affected...
Climate change is expected to have both direct and indirect effects on water
resources. Hydrologic impacts of two indirect effects, vegetation density and stomata!
conductance, are evaluated for the American River, a 200 km² watershed in the
Cascade Range of Washington state. First, a set of distributed hydrology-biogeochemistry
model structures...
This study evaluated the effects of tillage system, rotational tillage sequences, and winter seed burial depth on weed seedling recruitment in irrigated cropping systems. Notill (NT) planting of vegetable crops reduced emergence of hairy nightshade by 77 to 99% and Powell amaranth emergence from 50 to 87% compared to conventional...
Marine sediments contain an abundance of methane that is biologically produced
and plays a significant role in the global carbon cycle. Microbes responsible for the
carbon cycle in marine sediments, and the processes that they carry out, need to be
characterized in order to fully understand the role of this...
This dissertation explores the engineering of carbon nanotube electronic devices using atomic force microscopy (AFM) based techniques. A possible application for such devices is an electronic interface with individual biological molecules. This single molecule biosensing application is explored both experimentally and with computational modeling.
Scanning probe microscopy techniques, such as...
Two vintages of Vitis vinifera cv. Pinot noir wine from a viticulture trial evaluating nitrogen fertilization, tilling and irrigation underwent descriptive analysis using a modified version of free-choice profiling. Wines were made from three field blocks of the twelve factorial combinations of Irrigation (Dry or Irrigated), Tillage (Tilled or not...
Vegetation diversity in the Wyoming big sagebrush/Thurber needlegrass (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young/Achnatherum thurberianum (Piper) Barkworth. syn. Stipa thurberiana Piper) plant association was studied across a condition class gradient in southeastern Oregon. All observable vascular plant species were counted during 6 seasons and 2 years and diversity...
A better understanding of grass seed crop and soil fertility is necessary to
improve fertilizer practices and preserving water quality in Willamette Valley,
Oregon, where 55% of land-use is in grass seed production that directly impacts
adjacent waterways containing native protected fish species. I determined tillage
effects on soil N...
Low-permeability geologic units may offer significant chemical and hydraulic protection of adjacent aquifers, and are important for managing groundwater quality, especially in areas with significant non-point source contamination. Nitrate in the Willamette Valley is attenuated across the Willamette Silt, a semi-confining unit overlying a regionally important aquifer. To quantify the...
This research examines the factors that influence consumer choice of organic over conventional fresh produce. The emphasis of this study is to determine the relative importance of environmental and health motives and economic factors in explaining this choice. A survey was designed to collect data about consumer preferences and purchasing...
Unpaved roads are sources of chronic sediment in forested watersheds. Bare soil on roads is exposed to erosion from rainfall and runoff Published research on sediment production from forest roads focuses primarily on road characteristics. Since water drives the mechanics of sediment transport, hydrologic variables should correlate with sediment production....
Mass transfer processes were evaluated in an artificial, non-uniform porous medium with a power law distribution of diffusion rate coefficients obtained from physical characterization of solute and porous medium. Breakthrough curves of several pulse experiments conducted at different velocities were compared (1) to analytical expressions for concentrations at mass transfer...
Thermal stabilization of chlorophyll and anthocyanin on pear peels during thermal process was investigated in this study. The green color of peels-on thermally processed (canned) pears was successfully retained by complexation of magnesium-free chlorophyll with zinc ions, and the red pigments were stabilized through anthocyanin-stannous complexation and polymerization of pear...
The gravel aquifer of the Oregon side of Walla Walla River Basin has a strong hydrologic connection to surface water through a series of springs, unlined irrigation canals, the Walla Walla River, numerous wells and, since 2004, artificial recharge to the shallow aquifer using infiltration basins. The finite element Integrated...
An ASR metric and site rating index applied to over 120 municipal and agricultural locations across Oregon, combined with comparison to case study data from existing ASR sites, indicate that more than 50% of selected sites are hydrogeologically suitable for ASR. The ASR metric is a ratio of aquifer storage...
Saturated hydraulid conductivity (Ks) is a central soil physical property in determining water movement and contaminant transport through soils; hence modeling this system requires an accurate determination of K. Decimeter-scale KS measurements employing cores or infiltrometers are used frequently, but field-scale KS values are required to encompass the full range...
Relatively recent increases in ponderosa pine abundance have effected unprecedented changes to ecosystem structure and function. Efforts to restore ponderosa pine systems are often focused on the manipulation of tree structure and the re-introduction of a more natural fire regime. Successful restoration should also incorporate understory components but information addressing...
The specific objectives of this dissertation are to determine subsurface flow
behaviors across different antecedent wetness conditions from a top-down perspective
and to mechanistically assess the hydrological controls on DOC and N transport at the
hillslope and catchment scale. The study area is a small catchment where hillslopes
issue directly...