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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Learning Peaks for Commercial and Industrial Electric Loads

B Hari Kiran Reddy (11824361) 18 December 2021 (has links)
<div>As on 2017, US Energy Information Administration (US EIA) claims that 50 % of the total US energy consumption are contributed by Commercial and Industrial (C&I) end-users.</div><div>Most of the energy consumption by these users is in the form of the electric power. Electric utilities, who usually supply the electric power, tend to care about the power consumption profiles of these users mainly because of the scale of consumption and their significant contribution</div><div>towards the system peak. Predicting and managing the peaks of C&I users is crucial both for the users themselves and for utility companies.</div><div>In this research, we aim to understand and predict the daily peaks of individual C&I users. To empirically understand the statistical characteristics of the peaks, we perform an extensive exploratory data analysis using a real power consumption time series dataset. To accurately predict the peaks, we investigate indirect and direct learning approaches. In the indirect approach, daily peaks are identified after forecasting the entire time series for the day whereas in the direct approach, the daily peaks are directly predicted based on the historical data available for different users during different days of the week. The machine learning models used in this research are based on Simple Linear Regression (SLR), Multiple Linear Regression (MLR), and Artificial Neural Networks (ANN).</div>
42

AMPHIBIAN USE OF RESTORED WETLANDS OF DIFFERENT AGES

Patrick James Ransbottom (11785331) 20 December 2021 (has links)
<div>Wetland-dwelling amphibians are of conservation interest for numerous reasons. They serve as biological indicators of water quality during their fully aquatic larval phase, and as carnivores that prey extensively on both terrestrial and aquatic invertebrates. These amphibians are an important link between terrestrial and aquatic food webs, and their wellbeing is an important factor when considering ecosystem health. Amphibians are facing global declines as their wetland habitats are being lost or degraded by human actions. There are efforts to restore wetland habitats, but it is far from certain which practices encourage amphibian occupancy.</div><div>I investigated which factors are important to the persistence of amphibians in restored and naturally formed wetlands to see if restored wetlands can accommodate similar species assemblages. Amphibians were surveyed over two years in a collection of 18 wetlands in Steuben and DeKalb counties, IN owned by The Nature Conservancy. Ambystomatid salamanders were surveyed using plastic minnow traps in springtime, and frogs were surveyed using call surveys in spring and summer. I used linear models to compare wetland plant dominance, wetland hydroperiod, restoration status, distance to nearest mature forest, adjacent forest age and basal area, and inter-wetland distance to amphibian species richness.</div><div>The species richness of Ambystoma salamanders was positively associated with larger wetlands, higher forest basal area, and central mudminnow presence; and negatively associated with older forests, distance to mature forests, and the presence of sunfishes. Ambystoma salamanders besides A. tigrinum were associated with ephemeral hydrology, naturally-formed wetlands, and a greater number of wetlands within one km; and negatively correlated with older forests.</div><div>Frog species richness was positively associated with larger wetland size, and negatively associated with seasonal wetlands, naturally-formed wetlands, distance to nearest mature forests, naturally formed wetlands, treatment for invasive plants, and number of other wetlands within 500m. Total amphibian species richness models did not perform well, but showed a preference for semi-permanent wetlands, smaller distance to mature forests, greater forest basal area, and greater distance between wetlands; and a preference against Scrub Shrub/Forest wetlands. Hylid frogs were negatively correlated with naturally formed wetlands. Ranid frogs were associated semi-permanent wetlands and negatively correlated with the number of other wetlands within 500 m.</div><div>Ambystomatid salamanders were found in restored wetlands, semi-permanent wetlands, and in wetlands containing central mudminnows. Frogs may dislike the disturbance from removing invasive grasses. Managers should factor the disparate habitat requirements of amphibian taxa into their plans for creating and managing restoration projects. Different amphibian groups appear to differ greatly in their habitat requirements, and diverse wetlands may enhance the species richness of an area. Skillfully restored wetlands appear to serve similar functions to original, naturally formed ones.</div>
43

TIRE DEFORMATION MODELING AND EFFECT ON AERODYNAMIC PERFORMANCE OF A P2 RACE CAR

ROTEM LIVNY (11071605) 11 August 2021 (has links)
<div>The development work of a race car revolves around numerous goals such as drag reduction,</div><div>maximizing downforce and side force, and maintaining balance. Commonly, these goals</div><div>are to be met at the same time thus increasing the level of difficulty to achieve them. The</div><div>methods for data acquisitions available to a race team during the season is mostly limited to</div><div>wind tunnel testing and computational fluid dynamics, both of which are being heavily regulated</div><div>by sanctioning bodies. While these methods enable data collection on a regular basis</div><div>with repeat-ability they are still only a simulation, and as such they come with some margin</div><div>of error due to a number of factors. A significant factor for correlation error is the effect of</div><div>tires on the flow field around the vehicle. This error is a product of a number of deficiencies</div><div>in the simulations such as inability to capture loaded radius, contact patch deformation in</div><div>Y direction, sidewall deformation and overall shifts in tire dimensions. These deficiencies</div><div>are evident in most WT testing yet can be captured in CFD. It is unknown just how much</div><div>they do affect the aerodynamics performance of the car. That aside, it is very difficult to</div><div>correlate those findings as most correlation work is done at WT which has been said to be</div><div>insufficient with regards to tire effect modeling. Some work had been published on the effect</div><div>of tire deformation on race car aerodynamics, showing a large contribution to performance</div><div>as the wake from the front tires moves downstream to interact with body components. Yet</div><div>the work done so far focuses mostly on open wheel race cars where the tire and wheel assembly</div><div>is completely exposed in all directions, suggesting a large effect on aerodynamics.</div><div>This study bridges the gap between understanding the effects of tire deformation on race car</div><div>aerodynamics on open wheel race cars and closed wheel race cars. The vehicle in question</div><div>is a hybrid of the two, exhibiting flow features that are common to closed wheel race cars</div><div>due to each tire being fully enclosed from front and top. At the same time the vehicle is</div><div>presenting the downstream wake effect similar to the one in open wheel race cars as the</div><div>rear of the wheelhouse is open. This is done by introducing a deformable tire model using</div><div>FEA commercial code. A methodology for quick and accurate model generation is presented</div><div>to properly represent true tire dimensions, contact patch size and shape, and deformed dimension,</div><div>all while maintaining design flexibility as the model allows for different inflation</div><div>pressures to be simulated. A file system is offered to produce CFD watertight STL files that</div><div>can easily be imported to a CFD analysis, while the analysis itself presents the forces and</div><div>flow structures effected by incorporating tire deformation to the model. An inflation pressure</div><div>sweep is added to the study in order to evaluate the influence of tire stiffness on deformation</div><div>and how this results in aerodynamic gain or loss. A comparison between wind tunnel</div><div>correlation domain to a curved domain is done to describe the sensitivity each domain has</div><div>with regards to tire deformation, as each of them provides a different approach to simulating</div><div>a cornering condition. The Study suggests introducing tire deformation has a substantial</div><div>effect on the flow field increasing both drag and downforce.In addition, flow patterns are</div><div>revealed that can be capitalized by designing for specific cornering condition tire geometry.</div><div>A deformed tire model offers more stable results under curved and yawed flow. Moreover,</div><div>the curved domain presents a completely different side force value for both deformed and</div><div>rigid tires with some downforce distribution sensitivity due to inflation pressure.</div>
44

THE IMPACT OF DIETARY FIBER AND SUCROSE ALTERNATIVES ON TEXTURE PERCEPTION OF COOKIES

Sarah L Pitts (11565889) 22 November 2021 (has links)
<p>Low moisture baked goods (cookies, biscuits, etc.) are known for their high sugar content, low water content, and characteristic texture. The added sugar in baked goods has been a concern of health advocates due to the negative health implications of overconsumption of sugar. To minimize these health implications and support healthier food products, the replacement of sugar, sucrose, in low moisture baked goods with alternative sweeteners is of interest. The goal of this study was to improve understanding on how sweetener alternatives and dietary fiber interact with cookie ingredients and the subsequent cookie texture compared to sucrose containing cookies to aid in developing health-conscious low moisture baked goods.</p><p> The replacement of sucrose with sucrose replacers (SRs) encompassing a variety of structural and physicochemical properties (high fructose corn syrup (HFCS), amorphous sucrose, maltitol, allulose, isomalt, Benefiber, Miralax, fructooligosaccharides (FOS), and isomalto-oligosacchrides (IMO)) in wire-cut cookies was investigated in terms of starch thermal properties, model cookie formulations, and sensory descriptive analysis. Starch thermal properties were investigated using differential scanning calorimetry (DSC) while wire-cut cookie parameters were analyzed through a<sub>w</sub>, color (<i>a, b, L</i>), moisture loss, cookie dimensions (height, width, length), and cookie hardness (N) assays. Sensory descriptive analysis was used to ascertain texture perception of wire-cut cookies through five attributes (hardness, fracturability, pastiness, cohesiveness, and crumbliness).</p> The onset gelatinization temperature (T<sub>gel</sub>) was increased to a greater extent than sucrose by Miralax and FOS, and to the same extent by IMO, maltitol, and Benefiber at high concentrations (60%w/w). The SRs which performed similar to sucrose in wire-cut cookie baking (spread, moisture loss, hardness) and texture intensity ratings were amorphous sucrose, maltitol, and allulose. No significant differences in descriptive analysis intensity scores were found in crumbliness, cohesiveness, and pastiness between SRs and sucrose formulated wire-cut cookies. FOS, IMO, and Benefiber displayed significantly larger fracture intensity scores compared so sucrose and isomalt cookies were significantly less hard than sucrose cookies. Principal component analysis (PCA) related SRs effect on starch gelatinization, cookie baking properties, and descriptive analysis intensity scores, and indicated the mostly likely candidates for use in reduced sugar cookies are maltitol and allulose.
45

Investigation of research-proven comfort and support strategies for students with autism aspectrum disorder

Carmen Yvette Cleaveland (8785943) 01 May 2020 (has links)
One out of every twenty children in school is affected, in significant ways, in classrooms across our nation by sensory processing disorders (SPD) (Nodding, 2017). In classrooms where students with Autism Spectrum Disorder (ASD) are present, that number rises even higher because almost 100% of students with ASD experience SPD (Murray, Baker, Murray-Slutsky & Paris, 2009). Teachers must understand the unique needs of students with SPD in order to create environments where students feel comfortable to learn in every day. Optimal learning for students with SPD requires an environment that supports and assists them to effectively and systematically organize and understand the information they are taught. Unfortunately, most classrooms present sensory challenges that can be frustrating or even overwhelming for students diagnosed with SPD. The daily negative experience at school often adds more stress for these students due to their social interactions and how they regulate emotions (Lytle and Todd, 2009).<div><br></div><div>There are two purposes of the study: 1) general education teachers’ use of interventions to support students with ASD and SPD was examined to determine what worked most effectively in their classrooms, and (2) general education teachers’ perception of barriers for implementing research-based strategies was examined in order to identify potential problems in creating supportive environments for students with ASD and SPD in the general education classroom. Eighteen teachers participated in the study at a private school with 335 students in a suburban area. The survey included 8 questions about the effectiveness of sensory interventions for students with ASD and/or SPD at school.<br></div><div><br></div><div>The result of this study showed that the majority of teachers want to be supportive to students diagnosed with SPD. Seventeen teachers (94%) expressed a concern for students who may feel overwhelmed by providing some variation of a calming area within their classroom Concerning the use of flexible seating, 6 teachers (33%) responded that they do not offer flexible seating, and 3 teachers (17%) indicated it was the least effective intervention they offered students. These responses could indicate that there is misunderstanding concerning the use of flexible seating and how to effectively implement it within the general education classroom. Another notable result is that 7 general education teachers (39%) indicated they lacked the space to provide a calming area for students in their classrooms.<br></div><div><br></div><div>The result of the current study supports the findings in previous research that there is a need for teachers to be more knowledgeable about how to create classrooms that offer support, effective strategies for students diagnosed with SPD. A handbook was created for general education and special education teachers based on the result of the present survey study and findings in previous studies. This handbook focuses on clear explanations of the unique stresses that students with SPD face, with the hope that if teachers have a clearer understanding about the needs of these students, they will be inspired to consistently offer research-proven strategies to support and encourage their students who face unique challenges in the school environment every day. <br></div>
46

An Experimentally-Validated Coupled Opto-thermal-electrical Model for PV Performance and Reliability

Yubo Sun (8803139) 07 May 2020 (has links)
Photovoltaics (PV) are a renewable energy technology experiencing rapidly increasing commercial adoption today. Nonetheless, many proposed PV applications still require higher efficiencies, lower costs and comparable reliability to currently available in commercial devices (typically made from silicon). To enable the rigorous study of a much wider range of materials and novel design concepts, particularly those based on compound thin films, Concentrated Photovoltaics (CPV), cells with bifaciality, a comprehensive modeling framework is developed to couple photon absorption, carrier transport, photon recycling, and thermal transport in PV devices. The universality of this framework manifest itself in approaching various PV related problems as follows: 1) exploring the novel design of wide-Eg GaInP solar cells as an intermediate step to enhance the efficiency of multijunction PV devices; 2) characterizing the open-circuit voltage (VOC) degradation in thin-film vapor liquid solid (TF-VLS) grown InP solar cell through combined device and circuit model for interpreting photoluminescence (PL) image; 3) establishing optic-electric-thermal coupled framework to assess and compare the passive cooling effect for Silicon CPV devices that employ porous soda-lime glass radiative cooler and conventional copper cooler respectively; 4) Investigating and formulating the analytic solution of the optimal design that minimizes combined optical shadowing loss and electrical resistive loss for two types of bifacial PV devices: a) interdigitated back contact (IBC) Silicon heterojunction (SHJ) solar cells and b) Copper Indium Gallium DiSelenide (CIGSe) solar cell with Al2O3 passivation; and 5) Constructing an Neural Network Autoen- coder (NNA) that compresses and reconstructs the J-V characteristics obtained from TCAD simulation and literature for rapid screening and automated classification.
47

PROPAGATION OF EN-ROUTE AIRCRAFT NOISE

Yiming Wang (8028554) 25 November 2019 (has links)
The prediction of the noise generated by en-route aircraft is gradually gaining in importance as the number of aircraft increases over the last few decades. While the studies of outdoor sound propagation have been focused on near ground propagation, the case when the sound source is high above the ground has not attracted much attention. At the same time there has been a lack of high-quality aircraft acoustic validation data sets that contain detailed acoustic, meteorology, and source-receiver position data. The DISCOVER-AQ data set, which was collected by Volpe in support of the Federal Aviation Administration (FAA), has greatly helped with studying the directivity and the Doppler effect in the comparison between simulation results and measurements. <div><br>To provide a more accurate prediction of en-route aircraft noise, we derived the analytic asymptotic solution of the sound field above a non-locally reacting ground due to a moving point source and a line source using the methods of the steepest descent and a Lorentz transform. The model predicts a much more accurate result for sound field above "soft" grounds, such as a snow-covered ground and sand-covered ground. At the same time, we derived a fast numerical algorithm based on Levin’s collocation for the prediction of the sound field in the presence of a temperature gradient, which can be applied to a wide range of acoustic problems involving integration. The achievements recorded in this thesis can be used to predict the sound field generated by aircraft, trains, and vehicles with a subsonic moving speed. In addition,<br>the model can be used for detection and design of moving sound source. <br></div>
48

Annoyance thresholds of tones in noise as related to building services equipment

Guochenhao Song (9755876) 14 December 2020 (has links)
<div><div><div><p>Tonal sounds are a particular problem of concern in building environments, arising from the widely used rotating machinery (e.g., compressors, fans, motors, trans- formers, etc.). In the recent trend of designing and manufacturing high-performance building mechanical systems, higher output power and higher rotation speed are pursued, this inevitably results in a more severe noise problem, since the equipment noise not only becomes louder but also shifts to a higher frequency region (which, in most cases, results in a poorer sound quality due to the shift in spectral balance and tonal components moving into the frequency regions where people are most sensitive to tones). Tonal sounds from rotary machines can be annoying, even at relative low levels.</p><p>Currently, noise criteria guidelines in Chapter 48 of the ASHRAE HVAC Applications Handbook can be used to design the building mechanical system, but this does not apply well for tonal noise. Reducing the limit for noise with perceptible tones is one common strategy in the industry. However, it’s not adequate for some cases, over-design in others. Thus, an adequate understanding of the annoyance threshold of tonal noises associated with building services equipment is valuable technical information not only in the design and manufacture of machines but also in the development of noise regulations related to building services equipment.</p><p>This research aims to develop a sound quality model that cooperates with sound level and tonalness and relates tonal building noises to the perceived annoyance.</p></div></div></div>
49

AN EXAMINATION OF RELATIONSHIPS BETWEEN CLIMATE AND FISH COMMUNITIES IN AGRICULTURAL HEADWATER STREAMS

Darren J Shoemaker (10271492) 12 March 2021 (has links)
<p>Fish communities in agricultural headwater streams are known to be impacted by a variety of factors, including water chemistry, habitat modification, and hydrology. Little research has been conducted on how climate change influences these communities, yet the effects of climate on lake and river fish have been well documented. I hypothesized that fish community metrics would be reduced by the effects of climate change. I examined the effects of climate and hydrology metrics on fish communities at nine sites in the Saint Joseph River, Indiana and Michigan and at 18 sites in the Upper Big Walnut Creek, Ohio watersheds, from 2006 to 2019. Air temperature, water temperature, precipitation, water discharge, width, velocity, and depth metrics were calculated seasonally for each sampling year. Fish were examined seasonally with backpack electrofishing and seine netting and identified to species level. Principal component analyses were used to create axes which represented gradients of climate and hydrology metrics. Linear mixed effect and logistic regression modeling suggested that hydrology is a stronger predictor than climate, but that both influence fish communities. Percent Percidae, percent herbivore, and percent open substrate spawner were positively correlated with precipitation and water temperature. Presence herbivore was negatively correlated with precipitation and positively correlated with water temperature. My data only somewhat supported the hypothesis that climate would reduce fish community metrics. Gradients of hydrology were observed to be stronger predictors than gradients of climate. However, one must acknowledge relationships between climate and hydrology and the potential for climate to have indirect effects on fish communities through influences on hydrology. This study increases understanding of how fish communities in agriculturally dominated headwater streams are influenced, and emphasizes the need for further research on how these fishes will be impacted by a changing climate. </p>
50

Microdroplets: Chemistry, Applications and Manipulation Using Ionization Sources and Mass Spectrometry

Kiran S Iyer (6833102) 04 December 2019
There is widespread use of ionization sources (ambient and non-ambient) for a variety of applications. More recently, charged microdroplets generated by electrospray ionization and paper spray have been used to conduct chemistry at faster rates compared to bulk volumes. Uncharged droplets such as those generated by the Leidenfrost technique have also been used to explore chemistry and study the degradation of drugs in an accelerated manner. These microdroplets serve as reaction vessels in which in which some reactions are known to occur at accelerated rates. Such chemistry can be particularly useful in pharmaceutical settings to rapidly synthesize small amounts of materials in relatively short amount of time. Additionally, microdroplets may also be used to perform high throughput screening analysis. While several parameters influencing the rate of reaction in microdroplets have been explored (such as spray distance and reagent concentration), the mechanism of reaction acceleration has not been probed to a significant extent. A major portion of my dissertation describes the use of charged and uncharged microdroplets to perform quick chemistry, guide microfluidic synthesis of drugs such as diazepam, perform scale up of copper catalyzed C-O and C-N coupling reactio<a></a>ns and screen reaction conditions for pharmaceutically relevant reactions such as the Suzuki cross-coupling reaction. Additionally, work discussed here also describes development and use of existing techniques such as structured illumination microscopy to measure droplet sizes, explore the role of distances on droplet size, and study the effect of surfactants on the rate of reactions in microdroplets generated by nano-electrospray ionization. A mathematical model to understand the mechanism of increased reaction rates in microdroplets has also been presented. Additionally, this dissertation also describes ways to manipulate ions in air using various designs of 3D-printed electrodes that operate with DC potentials only and which can be easily coupled with nano-electrospray ionization sources to transmit ions over long distances

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