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3D Printing of Wood-Sodium Silicate Composites
No full textAdditive manufacturing (AM) for construction applications has grown rapidly over the past 10 years. AM, also referred to as 3D printing, in construction has primarily been done with concrete as a medium up to this point. AM has the ability to rapidly manufacture complex geometry not possible with conventional building techniques. Additionally, AM has the ability to use recycled materials and produces very little waste. Wood-based composites have yet to be used in AM for the construction industry because a method to produce high strength wood-based composites in AM has not been developed. This study details the development of an AM method for wood-sodium silicate composites (WSSC). A 3D printer was designed and constructed utilizing a screw extruder for wood-based composites capable of extruding wood-based composites and depositing them layer by layer onto the printer’s bed. The printer is designed to use a feedstock material of wood flour and a thermoset resin binder. The samples were printed at various wood to resin ratios and were cured at various temperatures. The WSSC’s adhesion to the print bed was assessed in addition to the interlayer adhesion of the printed WSSC during extrusion and after curing. A panel was successfully constructed with wood element size less than 40 mesh, at a 45:55 wood to sodium silicate weight ratio and cured for two days at 60°C. When stressed in bending, the bond between panel layers did not fail, rather failure occurred in the base material. The failures happening away from the boundary layers are consistent with other manufactured wood composites. Thus, AM can be a suitable manufacturing technique for wood-based composites based on the interlayer adhesion.masters, M.S., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2022-0
Health and Environmental Protective Behaviors Towards Water Pollution Threats in the Pacific Northwest
No full textWater pollutants remain a pertinent public health and environmental issue despite multiple policies to control water pollutants from entering the environment. Community members engaging in both health and environmental protective behaviors can prevent excess water pollutants from entering water bodies, protect drinking water and their personal health. Existing social science research has primarily focused on either health protective behaviors or environmental protective behaviors, but rarely considered these behaviors together. As such, little is known about what motivates both types of behaviors within the same environmental issue. This thesis contributes to a broader understanding of factors that encourage both health and environmental protective behaviors in the Pacific Northwest (PNW) using data from an online survey (n = 621). In the first empirical chapter, I 1) explore threat and coping variables that contribute to both types of behaviors and 2) explore the relationships between subjective knowledge and sociodemographic variables that contribute to both types of behaviors. Results reveal that high self-efficacy significantly predicted both health and environmental protective behavioral intentions for water pollutants, while perceived severity of the threat was only significant in the environmental model. Perceived vulnerability and response efficacy were significant in both models. Education level, political affiliation, and subjective knowledge were significant predictors of environmental protective behavioral intentions, but not health protective behavioral intentions. Overall, the results of this study suggest that when communicating environmental risks of water pollution, highlighting self-efficacy in messaging is particularly important to promote protective environmental and personal health behavior. In the second empirical chapter, I further investigate motivators of environmental protective behavior through communication frames. There has been little experimental research testing how to effectively communicate information about water pollution to encourage protective behavior. This project used a message framing experiment embedded in an online survey to determine how (a) personal versus impersonal risk frames and (b) self-efficacy versus no self-efficacy frame were effective in encouraging health and environmental protective behavior intentions. We conducted parallel studies with samples from two populations: the Qualtrics panel (n=621) and a university student population (n=178). We found that among the general population, no communication frame was more effective than another to encourage behaviors. Among the student population, we found that the personal risk frame with no self-efficacy message had a significantly higher effect on respondents’ intentions to engage in environmental protective behaviors compared to messages with self-efficacy. We found that the average respondent reported high intentions to take protective behaviors toward water pollution, which may suggest that self-efficacy messaging is not necessary when communicating personal risks for a high salience issue. In the Conclusion, I discuss implications for results from both empirical chapters in the context of communication best practices for health and environmental protective behavior change and opportunities for future research.masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2022-1
Exploring the Effects of Vegetation and Vegetation-Induced Topography on the Distributions of Near-Bed Flow Parameters
No full textVegetation is a vital component of river systems because it impacts habitat and flow and changes sediment transport regimes and local bed topography. Specifically, rigid emergent vegetation changes turbulence intensities, velocities, and shear stress near the bed, which contributes to erosion and deposition in vegetation patches. However, the effects of vegetation density on spatial distributions of near-bed flow parameters are not well understood. Furthermore, no studies have investigated the relative effects of vegetation and vegetation induced topography on near-bed flow. We conducted three laboratory flume experiments with a single stalk and flat bed, a single stalk with a scour hole, and a scour hole with no stalk to investigate the individual effects of a vegetation stalk and a scour hole on the distributions of near-bed velocities, Reynolds stresses, and turbulent kinetic energies (TKE). We also used experiments from another study to test the accuracy of previously published equations for mean channel velocity (U) and spatially averaged TKE (〈???〉) in flat beds with data from a bed with vegetation and natural bed topography. Lastly, we fit a gamma distribution to the TKE distributions from the single stalk experiments and from experiments from another study. Our goal was to find a relation between fit parameters of the gamma distribution and mean channel velocity to predict the shape and scale parameters of a TKE distribution from mean channel velocity. We found that equations designed for flat beds predict mean channel velocity and mean near-bed turbulent kinetic energy fairly well for low measured U and 〈???〉 in beds with natural topography and vegetation. Not all experimental TKE data fit a gamma distribution well, however a relation may exist between vegetation density and the shape parameter of a two-parameter gamma distribution.masters, M.S., Civil & Environmental Engr -- University of Idaho - College of Graduate Studies, 2022-0
From the Laboratory to the Field: Investigating the Effect of Biochar on Forest Insects
No full textABSTRACT Insects provide numerous ecosystem services in a forest environment, such as pollination, nutrient cycling, as well as providing disturbance. Defoliating lepidoptera such as Douglas-fir tussock moth (Orgyia pseudotsugata Lepidoptera: Erebidae) attack healthy trees, predominantly true firs (Abies sp.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and spruce (Picea sp.), and convert tree foliar biomass into frass, contributing soil organic matter within the forest ecosystem that benefit soil organisms. In outbreak years, high densities of O. pseudotsugata may consume all available foliage. Defoliation of large forest stands allows for light to penetrate to the undergrowth and accelerate the regenerative succession of the forest stand. Wood boring insects including bark beetles help to cycle nutrients by increasing the rate of breakdown of woody material which also contributes to accumulation of soil organic matter. Biochar is a carbon-rich material made via thermochemical decomposition of organic matter in a high temperature, low oxygen environment. Biochar can be created from many types of organic material such as discarded slash material during logging of overstocked stands or beetle killed trees, and used as a soil amendment to restore degraded soils. Biochar has been used to sequester carbon, and to increase soil water holding capacity and plant available water. Forest insects may be exposed to biochar when the material is applied to surface organic horizons and downed trees. The results of recent laboratory studies show a potential negative effect on insects exposed to biochar material, although field experiments are necessary to establish how insects are affected by the application of biochar in a forest system. In the first experiment, direct exposure of O. pseudotsugata to biochar either on the surface of or incorporated within synthetic diet negatively affected survival and weight gain of the insects. Although the physiological effects of biochar are unknown, the low 10% volume/volume biochar treatment potentially may lead to compensatory feeding by the insects. Two field experiments were performed using sections (bolts) of ponderosa pine (Pinus ponderosa Lawson & C. Lawson), to determine if biochar applied to the bark surface (1) interfered with attack or emergence of the pine engraver beetle Ips pini (Say) (Coleoptera: Curculionidae: Scolytinae) when bolts were baited with a pheromone lure, or (2) altered species richness or abundance of insect assemblages on non-baited bolts. Similar mean density of nuptial chambers and emergence indicated both control and biochar treated bolts were suitable habitat for I. pini. Species richness was greater in the non-treated control bolts compared to the bolts treated with biochar for emerged insects in the test that compared bolts that did not receive a pheromone treatment. Red turpentine beetles, Dendroctonous valens (LeConte) (Coleoptera: Curculionidae: Scolytinae) were more abundant in non-treated control bolts as compared with the biochar treated bolts. Colonization by other insect taxa were not found to be significantly different between non-treated control bolts and bolts treated with biochar, although the insects that emerged from each bolt varied.masters, M.S., Entomology, Plant Path & Nematology -- University of Idaho - College of Graduate Studies, 2022-0
Swimming in 'thin air': Evaluating the combination of hypoxic and thermal stress as an additive or a synergistic effect on Redband Trout (Oncorhynchus mykiss gairdneri)
No full textClimate warming causes both increases in extreme environmental water temperature and decreased dissolved oxygen (DO) concentrations (hypoxia) that induce stress in salmonid fishes including trout. Redband trout (Oncorhynchus mykiss gairdneri) have divergent ecotypes corresponding to a diverse range of thermal conditions from warm desert to cold montane ecosystems. Additionally, trout can alter their physiological phenotype to acclimate to environmental stressors. I predicted that warm acclimation would increase thermal tolerance, increase cardiac performance, and decrease hypoxia tolerance relative to the cooler acclimation temperature. Further, I anticipated that the impact of hypoxic and thermal stress would be lowest for the desert ecotype. The combination of hypoxia and acute temperature increase stress was postulated to have a synergistic effect on trout performance. Trout were collected from wild populations and acclimated to 21°C (near upper pejus temperature) and 15°C (within thermal optimum range) to model the desert and cold montane habitats, respectively, using two metric units. First, the time at loss of equilibrium (LOE) was recorded as a proxy for hypoxia tolerance where DO was decreased to ~12% saturation in an experimental tank. Second, cardiac phenotypic response, quantified by heart rate (ƒH), measured using an electrocardiogram (ECG) during acute temperature increase with 50% DO saturation (hypoxia) or full DO saturation (normoxia). Warm acclimated trout had significantly shorter time to LOE, and thus inferior hypoxia tolerance relative to the cold- acclimated trout (p ≤ 0.001). A significant interaction between ecotype and acclimation temperature took place at the 21°C acclimation temperature where the cool montane ecotype had significantly shorter time to LOE relative to the desert ecotype (p ≤ 0.05). Warm acclimated fish exhibited a significantly higher temperature at peak heart rate (Tpeak), and thus a superior thermal tolerance than cold-acclimated trout (p ≤ 0.001). As expected, the Tpeak was significantly greater for trout subjected to normoxia rather than hypoxia (p ≤ 0.05). No significant difference was detected for Tpeak response between ecotypes. The warm-acclimated trout displayed significantly lower ƒH at temperature increments 15-20°C (p ≤ 0.001) and 21- 22°C (p ≤ 0.05) relative to the cold- acclimated trout. Greater ƒH values indicate greater bioenergetic cost. As Tpeak increased with warm acclimation temperature, ƒH had decreased, indicating that thermal tolerance can vary inversely with cardiac performance. The ƒH values with both hypoxic and thermal stressors combined were not greater than the sum of ƒH for each isolated stressor, thus the combination of hypoxic and thermal stress was seen to have an additive rather than synergistic effect on trout performance.masters, M.S., Environmental Science -- University of Idaho - College of Graduate Studies, 2022-0
Simultaneous Frequency and Voltage Regulation with Static VAR Compensation
No full textRenewable energy sources (RES) are becoming increasingly prevalent in modern power systems. This increased penetration of RES helps to reduce carbon emissions due to power generation, but the nature of wind and solar electricity generation creates some unique problems from a power system stability perspective. Frequency stability in particular is a difficult aspect to maintain in a system with a high penetration of renewables. This is in part due to their lack of generator inertia and inability to alter generation on demand, requiring external power electronic devices to regulate the flow of power they produce to be in line with the stability needs of the system. As the world moves ever onward towards net-zero carbon emissions from power generation, new technologies or new applications of existing technologies will be needed to maintain a secure and stable power grid. In this thesis, it is shown that a modest SVC bank can effectively damp frequency oscillations caused by a misbehaving wind park due to load fluctuations. By using a PMU to track frequency and applying principles of Bode loop shaping, a frequency compensator is designed that allows the SVC to achieve this frequency damping while maintaining its ability to regulate voltage, the most common use case for SVCs, at the same time. By identifying system modes using non-parametric broadband power spectral density (PSD) estimation and designing the compensator around them, these common power electronic devices, SVCs and PMUs, can be used to add a great deal of frequency stability to systems that traditionally struggle with frequency control, specifically renewable energy sources such as wind parks that are rapidly increasing in prevalence in modern power grids.masters, M.S., Electrical and Computer Engineering -- University of Idaho - College of Graduate Studies, 2022-0
A Structured Search Engine for Deep Web Databases
No full textThroughout the years, researchers have striven to improve the quality of information retrieval from the web; especially for ordinary users who need the proper access to the desired information. Users mostly interact with the web through search engines and they tend to expect precisely what they asked for. As web databases (Deep Web) hold enormous amounts of high quality information that users need to access and leverage, we shed some light on the importance of searching the deep web rather than just querying it. Searching is more flexible than querying based on fixed variables. Searching the deep web can enhance information accessibility especially if it simulates user behaviour. Research interest is growing in the area of maximizing the usefulness of web search via utilizing the largest portion of the web (Deep Web). Search engines such as Google can only find indexed information that is present in the Shallow Web. In contrast, peeking into Deep Web databases is not possible for search engines such as Google. Search engines are not able to simulate SQL-like queries of database contents in a traditional or other intuitive human-like manner. In this work, we present a system called DeepQ to search the database contents behind the firewalls inside the deep web and show that these contents can be accessed using a structured query language treating them as a deep relational web. We leverage a recent proposed declarative deep web query language called DQL, and we present the contours of its implementation in the DeepQ system. We also believe that this work has the potential to demonstrate the Universal Relations model, as the user will be able to interact with databases that are hidden behind firewalls, and also search conveniently for information.doctoral, Ph.D., Computer Science -- University of Idaho - College of Graduate Studies, 2022-0
Tree-ring blue intensity based temperature reconstructions for temperate North America
No full textTree-ring records are invaluable sources of annually-resolved paleoclimate information that allow for the multi-centennial to multi-millennial contextualization of modern instrumental observations and trends. Within the Northern Hemispheric tree-ring record, substantial temporal and spatial limitations exist regarding the understanding of past temperature variability. In this body of work, I detail the refinement and application of the novel dendrochronological technique, blue intensity (BI), in order to develop a new network of tree-ring-based temperature proxy records across the mid-latitudes of North America. This dissertation, which heavily relies on the fundamental tree-ring principle of limiting factor, utilizes high-elevation tree-ring collections derived from Picea rubens and Picea engelmannii populations across the Appalachian, United States Rocky, and Sangre de Cristo Mountain ranges to examine the relationships between numerous tree-ring metrics (total ring-width, BI, and maximum latewood density) and climatic variables in temperature-limited montane environments. This body of work illustrates the first broad-scale application of BI methods as well as the first BI-based temperature reconstructions in North America below 45o latitude. In Chapter 1, I examine and demonstrate a strong, positive, and temporally stable relationship between late-growing season maximum air temperatures and the delta BI parameter using a P. rubens chronology from the southern Appalachian mountains of the eastern United States. In Chapter 2, I examine the application of using BI methods to create a composite latewood BI (LWB) P. engelmannii chronology from multiple sites across the Sangre de Cristo Mountains in northern New Mexico in order to develop a late-summer maximum temperature reconstruction for the southern Rocky Mountains that spans 1735-2015 CE. The reconstruction demonstrates fluctuating warm and cool periods during the latter portion of the Little Ice Age (ca. 1730-1850) and also documents substantial warming over the last decade, the trend of which appears to be anomalous within the context of the past ca. 280 years. In Chapter 3, I demonstrate the use of LWB to reconstruct current-year growing (warm) season maximum temperatures in the low-to-mid latitudes (30-50o N) of western North America. I detail the development of a new tree-ring network comprised of 26 LWB chronologies developed from living, high-elevation P. engelmannii sampled across the western United States. From this network, I develop 4 individual temperature reconstructions, which characterize regional temperature histories across western North America from northern Mexico to southern British Columbia over the past 4 centuries. Further, I compare these 4 temperature reconstructions to highlight the spatial patterns of regional temperature trends throughout time. This body of work and the subsequent reconstructions provide important updates and increased data point density to the tree ring temperature proxy network of the Northern Hemisphere. Additionally, I highlight the use of blue intensity methods at both low- and mid-latitude upper tree line locations to increase the presence of temperature-sensitive records at increasingly lower latitudes of the Northern Hemisphere. Finally, I conclude this dissertation with a brief synthesis detailing the current state of the global BI network and the anticipated future trajectory of BI methods within the paleoclimate community.doctoral, Ph.D., Geography & Geological Science -- University of Idaho - College of Graduate Studies, 2022-0
Learning before our Mistakes: Predicting Unintentional Injury by Predicting Error
No full textUnintentional injury remains a significant burden on society and has attracted a broad range of research. Previous injury research has identified a host of risk factors in various injury domains such as inhibitory control, age, cognitive development, and distraction for pedestrian injury. However, much is still left to explore despite extensive work to understand injury etiology. Human error research provides a robust framework to transcend domain-specific prediction by applying performance-shaping factors. In two studies, I examined the impact of several performance-shaping factors on an injury-relevant cross-contextual behavior, multiple object tracking. Specifically, each study examines the impact of task complexity, time pressure, sensory limitations, and nonverbal working memory span on multiple object tracking. The first study examined the impact of performance-shaping factors in an abstract dot tracking task. The second study examined the impact of performance-shaping factors in a pedestrian street-crossing scenario. In both studies, increases in time pressure and sensory limitations were associated with degraded performance and a higher task failure rate. Lower nonverbal working memory spans were also associated with poorer performance and higher failure rates in both studies. In the abstract dot tracking task, an increase in task complexity led to a reduction in performance and increased failure rate, but the relationship was the opposite in the pedestrian scenario. Implications for injury prevention and etiology research are discussed along with future directions.doctoral, Ph.D., Psychology & Communication -- University of Idaho - College of Graduate Studies, 2022-0