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Estimation Of The Fatigue Life Of Additively Manufactured Metallic Components Using Modified Strain Life Parameters Based On Surface Roughness, Peter Grohs

Masters Theses

In this study, a method is developed to estimate the effects of surface roughness on the fatigue life of additively manufactured titanium Ti6Al4V, aluminum 7075–T6, and steel 4340 alloys through modified strain life parameters using finite element analysis (FEA). This method is highly beneficial to the fatigue analysis of as-built additively manufactured metal components, which possess rough surfaces that reduce fatigue life significantly but are challenging to analyze directly using finite element simulation because of complex geometries, i.e., modeling an exact surface profile is arduous.

An effective stress concentration factor, incorporating roughness data, is defined to quantify their effects on …

Teens In The Somali Diaspora: An Evaluative Program Study, Jennifer Skuza

Journal of Youth Development

Program evaluation is a critical part of program sustainability because evaluation can inform improvements and document impact. Here, 2 Minnesota organizations came together in partnership with the Somali American community to work toward a shared vision, which was to develop a new sustainable program that prepared refugee and immigrant youth for their educational and workforce futures while supporting their cultural way of being. This article shares the evaluative study of this program, which reached teens in the Somali diaspora living in Minnesota. The program team had a long-term interest in developing an evidence-based model to suit this special population; this …

A Heavy Burden: Associations Between Sexual Minority Status, Mental Health, And Bmi In Women, Alison E. A. Goldblatt

Graduate Masters Theses

Sexual minority women (SMW) are at increased risk of elevated body mass index (BMI) compared to heterosexual women, which increases their vulnerability to a variety of chronic diseases. This increased risk of elevated BMI is likely due to unique minority stressors faced by sexual minority individuals, such as internalized heterosexism and discrimination. Minority stressors are associated with poorer mental and physical health among SMW, and SMW may engage in unhealthy coping strategies, like binge eating, to cope with these minority stressors. Research suggests that bisexual women, and other women with non-monosexual orientations, face elevated risks to their physical and psychological …

The Existing Intersectionality Of Gender And Race Differences In Science, Technology, Engineering And Math Fields, Rachael Carrillo

Undergraduate Honors Theses

This thesis will examine the gender differences women and men experience in Science, Technology, Engineering and Math fields (STEM) in undergraduate education focusing on the binary genders--men and women--and their experiences in STEM. Thus, the research question is: Do undergraduate women in STEM experience higher levels of gender differences compared to men in STEM? This is an important research question because if female undergraduates in STEM are experiencing sexism while their male colleagues are not, this phenomenon may create a large issue of inequalities for women in our society. STEM fields are typically higher paying fields and if women are …

Examining The Educational Experiences Of Community Day School Graduates: A Narrative Inquiry, Willie J. Jones Iii

Electronic Theses, Projects, and Dissertations

Community day school graduates enter society with decisions about college, career, and work. Community day schools operate as a non-traditional education system that provides a separate and often unique education to many disenfranchised students, with lessened accountability protocols to assess whether these systems prepare graduates for life after high school. The number of community day schools and enrollment is declining, due in part to excessive changes within the law and stricter guidelines required to be met.

Rank Reduction Of String C-Group Representations, Peter A. Brooksbank, Dimitri Leemans

Faculty Journal Articles

We show that a rank reduction technique for string C-group representations first used in [Adv. Math. 228 (2018), pp. 3207–3222] for the symmetric groups generalizes to arbitrary settings. The technique permits us, among other things, to prove that orthogonal groups defined on d-dimensional modules over fields of even order greater than 2 possess string C-group representations of all ranks. The broad applicability of the rank reduction technique provides fresh impetus to construct, for suitable families of groups, string C-groups of highest possible rank. It also suggests that the alternating group Alt(11)—the only known group having “rank gaps”—is perhaps more unusual …

Testing Isomorphism Of Graded Algebras, Peter A. Brooksbank, James B. Wilson, Eamonn A. O'Brien

Faculty Journal Articles

We present a new algorithm to decide isomorphism between finite graded algebras. For a broad class of nilpotent Lie algebras, we demonstrate that it runs in time polynomial in the order of the input algebras. We introduce heuristics that often dramatically improve the performance of the algorithm and report on an implementation in Magma.

6th Annual Sustainability Report, Saint Mary's College Of California

Sustainability Report

Highlights from the past year include reviving the Sustainability Living Learning Community in South Claeys (formerly called the “Green LLC”) with double the anticipated enrollment, representing Saint Mary's at Al Gore's Climate Reality Leadership Training in Minneapolis, and launching several new paid Sustainability Student Leadership positions.

Uncertainty And Error In Combat Modeling, Simulation, And Analysis, Jason A. Blake

Theses and Dissertations

Due to the infrequent and competitive nature of combat, several challenges present themselves when developing a predictive simulation. First, there is limited data with which to validate such analysis tools. Secondly, there are many aspects of combat modeling that are highly uncertain and not knowable. This research develops a comprehensive set of techniques for the treatment of uncertainty and error in combat modeling and simulation analysis. First, Evidence Theory is demonstrated as a framework for representing epistemic uncertainty in combat modeling output. Next, a novel method for sensitivity analysis of uncertainty in Evidence Theory is developed. This sensitivity analysis method …

An Interview With Aisha Sharif, Natalie Hayes

Gandy Dancer Archives

No abstract provided.

Production Of Biscuits By Substitution With Different Ratios Of Yellow Pea Flour, Jikai Zhao, Xin Liu, Xiang Bai, Fengcheng Wang

School of Earth, Environmental, & Marine Sciences Faculty Publications

To promote the commercialization of yellow pea flour (YPF) due to its nutritional benefits. Four biscuits with different YPF ratio (10%–50%) were conducted to explore the optimal addition percentage. The effects of YPF on the rheological and baking performance of biscuits were performed. The results showed that the substitution ratio of YPF and milling methods had a critical impact on the rheological properties of dough. The dough stability decreased gradually while a softening degree increased with YPF ratio increased. In a term of biscuits, the dimensions of length (L), width (W), thickness (T) and color (L*) of biscuits reduced as …

Predation Of Eastern Cottontail Rabbit (Sylvilagus Floridanus) By Great Blue Heron (Ardea Herodias), Carlos E. Cintra-Buenrostro, J. E. Cifuentes-Lujan

School of Earth, Environmental, & Marine Sciences Faculty Publications

An opportunistic predation by Great Blue Heron (Ardea herodias) on Eastern cottontail rabbit (Sylvilagus floridanus) was observed in south Texas on 31 Oct 2019. The Great Blue Heron had already captured the Eastern cottontail rabbit at the first observation but the maneuvering process, killing, and ingestion were recorded photographically, which make this observation unique even though this might constitute the second report on Great Blue Heron eating Eastern cottontail rabbits.

A Granger Causality Analysis Of Groundwater Patterns Over A Half-Century, Nitin K. Singh, David M. Borrok

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Groundwater depletion in many areas of the world has been broadly attributed to irrigation. However, more formal, data-driven, causal mechanisms of long-term groundwater patterns have not been assessed. Here, we conducted the first Granger causality analysis to identify the "causes" of groundwater patterns using the rice-producing parishes of Louisiana, USA, as an example. Trend analysis showed a decline of up to 6 m in groundwater level over 51 years. We found that no single cause explained groundwater patterns for all parishes. Causal linkages were noted between groundwater and area harvested, number of irrigation wells, summer precipitation totals, and drought. Bi-directional …

A Signature Enrichment Design With Bayesian Adaptive Randomization For Cancer Clinical Trials, Fang Xia

Dissertations and Theses (Open Access)

Clinical trials in the era of precision medicine demand more flexible and efficient trial designs. Adaptive clinical trial designs allow pre-specified modifications of an on-going clinical trial and could shorten the trial duration. We reviewed five common types of adaptive clinical trials based on adaptation methods. In particular, outcome-randomization becomes more popular as it can assign more patients to the promising treatments based on the accumulated trial data. This data-driven allocation allows more patients to benefit from the trial, which is especially important for cancer patients. We compared different Bayesian outcome-adaptive randomization methods and discussed them from both methodological and …

An Ai Approach To Measuring Financial Risk, Lining Yu, Wolfgang Karl Hardle, Lukas Borke, Thijs Benschop

Sim Kee Boon Institute for Financial Economics

AI artificial intelligence brings about new quantitative techniques to assess the state of an economy. Here, we describe a new measure for systemic risk: the Financial Risk Meter (FRM). This measure is based on the penalization parameter (λ" role="presentation" style="box-sizing: border-box; display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 18px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">λλ) of a linear quantile lasso regression. The FRM is calculated by taking the average …

Navigational Feasibility Of Flyby / Impact Missions To Interstellar Objects, Declan Moore Mages

Master's Theses

In October 2017, the first interstellar object, designated 1I/2017 U1 and more commonly referred to as Oumuamua, was detected passing through our solar system by the Pan-STARRS telescope, followed recently by the detection of 2I/Borisov in August 2019. These detections came much sooner than thought possible, and have redefined our understanding of the population of interstellar objects. With the construction of the next generation of powerful observatories, future detections are estimated to occur as frequently as two per year, and while there is significant scientific understanding to be gained from observing these objects remotely, a spacecraft sent to intercept one …

Hybrid Ground Vehicle Thermal Management System Using Heat Pipes—Model And Control, Junkui Huang

All Dissertations

The development of Hybrid Electric and Unmanned Ground Vehicles (HEV and UGV) offer various benefits including improved vehicle performance, compatibility with high level control systems, reduced fuel consumption, and less environmental pollution. According to the International Energy Agency (IEA), the number of HEVs and EVs is expected to reach 20 million by the year 2020 (Green Car Congress, 2017). Compared with traditional Internal Combustion (IC) engines, hybrid powertrains are more complicated due to additional electronics including the electric motor, battery pack, and control units. However, these additional components introduce new challenges for the powertrain thermal management system design since they …

Design And Evaluation Of Flow Mapping Systems For Heterogeneous Wireless Networks, Jianwei Liu

All Dissertations

Mobile wireless networks are always challenged by growing application demand. The increasing heterogeneity of both mobile device connection capability and wireless network coverage forms a general heterogeneous wireless network (HetNet). This type of HetNet contains sub-networks of different Radio Access Technologies. How to better coordinate the mappings of flows between Access Points (AP) and User Equipment (UE) inside this type of HetNet to improve system and user-level performance is an interesting research problem. The flow mapping systems used by off-the-shelf mobile devices make policy-based decisions from local information. Several global information based flow mapping systems that use Generalized Proportional Fairness …

A Case Of Arts Coordination In A Rural School District: A Distributed Perspective, Anna Shealy Wages

All Dissertations

Though researchers have demonstrated the benefit of prolonged engagement in the arts (Catterall, Dumais, & Hapden-Thompson, 2012) school districts struggle to maintain high quality programs. Rural programs, in particular, are faced with unique challenges to providing arts programs (Donovan & Brown, 2017). Despite these challenges, some rural school districts have succeeded in providing quality programs, which are more in line with more resourced urban districts. Arts researchers (Bodilly, Augustine, & Zakaras, 2008) have found that arts coordination is a strategy to increase access to and the quality of an arts program. Further, districts of quality, even small ones, have arts …

A Parallel Geometric Multigrid Method For Adaptive Finite Elements, Thomas Conrad Clevenger

All Dissertations

Applications in a variety of scientific disciplines use systems of Partial Differential Equations (PDEs) to model physical phenomena. Numerical solutions to these models are often found using the Finite Element Method (FEM), where the problem is discretized and the solution of a large linear system is required, containing millions or even billions of unknowns. Often times, the domain of these solves will contain localized features that require very high resolution of the underlying finite element mesh to accurately solve, while a mesh with uniform resolution would require far too much computational time and memory overhead to be feasible on a …

Optimizing Block-Stacking Operations With Relocation, Hueon Lee

Graduate Theses and Dissertations

The focus of the dissertation is developing the optimization problem of finding the minimum-cost operational plan of block stacking with relocation as well as devising a solution procedure to solve practical-sized instances of the problem. Assuming changeable row depth instead of permanent row depth, this research is distinguished from conventional block stacking studies.

The first contribution of the dissertation is the development of the optimization problem under the assumption of deterministic demand. The problem is modeled using integer programming as a variation of the unsplittable multi-commodity flow problem. To find a good feasible solution of practical-sized instances in reasonable time, …

Contributions Of Role-Playing Games: Advantages Of Incorporating Social Media In Disaster Response, Erin Mullin

Graduate Theses and Dissertations

After a disaster, emergency managers need to know who needs help, what type of help they need, and how soon they need it. Traditionally, they have relied on 911 calls and ground assessments to collect this information. Because the needs of a population are not able to be identified in a timely manner by ground assessments and because individuals are often unable to get through to 911, many civilians in distress turn to social media outlets as a last-ditch effort to obtain the services they need. Due to the uncertainty concerning the accuracy of social media posts, responding to disaster …

Oil Price Shocks, Fuel Subsidies And Macroeconomic (In)Stability In Nigeria, Babatunde S. Omotosho

CBN Journal of Applied Statistics (JAS)

This paper studies the macroeconomic implications of oil price shocks and the extant fuel subsidy regime for Nigeria. To do this, we develop and estimate a New-Keynesian DSGE model that accounts for pass-through effect of international oil price into the retail price of fuel. Our results show that oil price shocks generate significant and persistent impacts on output, accounting for about 22 percent of its variations up to the fourth year. Under our benchmark model (i.e. with fuel subsidies), we show that a negative oil price shock contracts aggregate GDP, boosts non-oil GDP, increases headline inflation, and depreciates the exchange …

Measuring Dynamic Return And Volatility Connectedness Among Nigerian Financial Markets, Elias A. Udeaja

CBN Journal of Applied Statistics (JAS)

This study employs the connectedness measure of Diebold and Yilmaz (2012, 2014) to examine the intensity of connectedness among the Nigerian financial markets for the period January 2000 to December 2018. The study used all shares index, Treasury bill rate and Naira/USD official exchange rate to measure stock market, money market and exchange rate market, respectively. The study found connectedness among the Nigerian financial markets to be highly time-varying and appear to be higher during the period of high depreciation of the naira which coincides with the period of falling oil prices and domestic economic meltdown of 2014 and 2016, …

The Classic, Winter 2019-2020, Public Relations

The Classic, 2010-2019

Zwemer View: Standout Courage and Faithfulness; Around the Green: Award-Winning Giving, In Box, Returning to Serve, HR MVPs, PA Program Gets Green Light, Schools for Syria, Campus Life: Dressember, Podcast for Educators, Extra! Extra!, Enrollment Sets Record, NWC Bandwidth Usage, Leaving NWC Financially Strong, Science Center Plaza, The Story Continues, Face Value: Tom Truesdell, Forever a Raider, Excellent Affirmed, Raider Nation Celebration, Bridge Builder, Comfort Keeper, Distinguished Alumni; Giving to Northwestern College in 2018-19; Red Zone: Double Threat; Looking Back: Closed Call; 1,000 Words: Making a Statement; Big Times in the Bultman: 10 of the Best Moments on the Raiders' …

Grounding Size Predictions For Answer Set Programs, Nicholas Hippen

Student Work

Answer set programming is a declarative programming paradigm geared towards solving difficult combinatorial search problems. Logic programs under answer set semantics can typically be written in many different ways while still encoding the same problem. These different versions of the program may result in diverse performances. Unfortunately, it is not always easy to identify which version of the program performs the best, requiring expert knowledge on both answer set processing and the problem domain. More so, the best version to use may even vary depending on the problem instance. One measure that has been shown to correlate with performance is …

Factors Limiting Reintroduced Plains Topminnow, Fundulus Sciadicus, Populations In Central Great Plains Streams, Joseph Thiessen, Keith D. Koupal, Casey W. Schoenebeck

The Prairie Naturalist

The plains topminnow (Fundulus sciadicus) is an endemic Great Plains stream fish that has experienced declines in geographic range and local abundance. Due to these declines, the species has been considered for federal protection and designated with conservation status in states throughout its historic range. The reasons for declines are likely similar to hypothesized factors for other endemic stream fish declines in the Great Plains. To investigate potential limiting factors a suite of 17 historic sites with reintroduced plains topminnow populations across Nebraska were evaluated for current populations and if plains topminnow were absent, additional fish were introduced. …

Review Of Grasslands And Climate Change By David J. Gibson And Jonathan A. Newman, Neal D. Noemuth

The Prairie Naturalist

The last decade has seen an explosion of information about climate change, some of which is contradictory, much of which is confusing, and the entirety of which is too much for the typical biologist or scientist to assemble and comprehend. This is why reviews such as Grasslands and Climate Change, edited by David Gibson and Jonathan Newman, are so valuable. To produce this review of climate change issues and influences relative to grasslands, Gibson and Newman recruited 30 scientists—predominantly from Europe and North America—who wrote 19 chapters dealing with various aspects of grasslands and climate change. The chapters are grouped …

Cost Effectiveness Of Greenhouse Gas Reductions Through Afforestation Of Agricultural Land In The Arkansas Delta, Karli A. Moore

Graduate Theses and Dissertations

Sequestration of atmospheric carbon in forested lands offsets carbon emissions from other industries. Conversion of private lands, particularly agricultural tracts in marginal areas, to forests can bolster carbon abatement. The United States government agencies administer some voluntary, incentive-based programs to encourage landowners to adopt production practices with positive environmental outcomes. This policy stream can be used to increase transition of marginal agricultural land to forests, thereby creating new carbon sinks. We analyze an eleven-county study area in the Arkansas Delta to determine feasibility for a subsidy focused on carbon abatement through afforestation. This study area is significant for two reasons: …

Period Estimation And Denoising Families Of Nonuniformly Sampled Time Series, William Seguine

Electronic Theses and Dissertations

Nonuniformly sampled time series are common in astronomy, finance, and other areas of research. Commonly, these time series belong to a family of signals recorded from the same phenomenon. Period estimation and denoising of such data relies on periodograms. In particular, the Lomb-Scargle periodogram and its extension, the Multiband Lomb-Scargle, are at the forefront of time series period estimation. However, these methods are not without laws. This paper explores alternatives to the Lomb-Scargle and Multiband Lomb-Scargle. In particular, this thesis uses regularized least squares and the convolution theorem to introduce a spectral consensus model of a family of nonuniformly sampled …