Statistics and Probability Commons^™

Design And Development Of Two And Three Dimensional Integration System For Highway Based On Webgis, Che Defu, Zhou Huajun

Journal of China & Foreign Highway

To address the inefficiencies, lengthy cycles, and high resource demands in the process of determining the annual project database for highway maintenance quotas in Liaoning Province, a 2D and 3D integration system for highways based on WebGIS was designed and developed. This system not only provides a macroscopic view of the geographic distribution and overall characteristics of highways but also offers a detailed and intuitive representation of the spatial relationships and conditions of roadbeds and pavement damage. The system meets the needs of modern highway management and can serve as a reference for other highway maintenance quota tasks.

Study On Relationship Of Solar Radiation Temperature And Pier‐Top Displacement Of Ultra‐High Thin‐Walled Hollow Pier, Liu Zhishen, Zhang Yifei, Song Fei, Su Jufeng, Ren Xiang

Journal of China & Foreign Highway

Thin-walled hollow piers are widely used in high-pier and long-span continuous rigid-frame bridges. Solar radiation-induced displacements at the tops of ultra-high thin-walled hollow piers can negatively affect the structural alignment and stress during construction and post-construction phases. Based on a 180 m high thin-walled hollow pier of a large bridge in Shaanxi Province, this paper analyzes the temperature field and pier-top displacement using data collected during two 24-hour periods: August 28-29 and October 11-12. The temperature field and pier-top displacement patterns over time were studied using finite element analysis. The results show that the temperature difference between the north and …

Model Test Study On Mechanical Characteristics Of Spherical Joints In Multi‐Point Support Swivel System, Zeng Lifei

Journal of China & Foreign Highway

As a critical load-bearing component in bridge swivel systems, the mechanical behavior of spherical joints is essential for the safety of bridge swiveling operations. This study focuses on the spherical joints of a multi-point support swivel system for the bridge over the Xiangyang North Marshalling Yard. Model tests were conducted to analyze the effects of the number of supporting legs, swivel speed, track smoothness, and wind load on the stress of spherical joints. The stress variation patterns of spherical joints under different working conditions were investigated. The results show that increasing the number of supporting legs improves the uniformity of …

Selection Of Phase Change Materials For Asphalt Pavement Based On Molecular Dynamics Simulation, Liu Fujun, Tian Xin, Liang Meichen, Guo Meng

Journal of China & Foreign Highway

Phase change materials (PCMs) have significant application potential in temperature regulation for asphalt pavements. To select suitable PCMs for road applications, this paper utilizes molecular dynamics simulation to analyze the molecular behaviors of lauric acid and polyethylene glycol (PEG). Experimental studies were conducted to validate the simulation results. The results show that molecular dynamics simulation provides an efficient and convenient method for comparing the performance of PCMs. PEG outperforms lauric acid in terms of molecular density, cohesive energy density, solubility parameters, and thermal conductivity, making it more suitable as a phase change material for asphalt pavements.

Study On Alkali Excitation Mechanism Of Large Dosage Slag Fine Powder, Mei Yang

Journal of China & Foreign Highway

To reveal the alkali excitation mechanism of high-dosage slag, this paper combines a three-factor, three-level orthogonal design with macro- and micro-performance tests and microstructure analysis. The effects of different activators, including Ca(OH)2, Na2SiO3, Na2SO4, and CaSO4, in single and dual combinations on the initial and final setting times, pore solution pH, and strength of concrete were explored. The results show that the impact on the strength of hardened paste of composite cementitious materials is ranked as: activator type > dosage > dual-mix ratio. The optimal dual-mix dosage is 4%, with the best combination being Ca(OH)2 and Na2SiO3 at a ratio of 5:1. …

Study On Microstructure Of Asphalt Modified By Oil‐Coal Blend, Guo Pengfei, Zhou Xinfeng

Journal of China & Foreign Highway

To investigate the microstructure and modification mechanism of asphalt modified with oil-coal blend, SK-90# asphalt was mixed with 5%, 10%, 15%, 20%, and 25% (external blending method) oil-coal blend to produce modified asphalt. The performance and microstructural changes of the modified asphalt were analyzed using contact angle testing, infrared spectroscopy, cross-sectional SEM, and X-ray photoelectron spectroscopy. The results show that the oil-coal blend exhibits good compatibility with asphalt. During the modification process, esterification reactions occurred, resulting in a decrease in hydroxyl-containing aromatic compounds and an increase in carbonyl-containing aromatic compounds. Macroscopically, the oil-coal blend-modified asphalt demonstrated excellent high-temperature performance.

Analysis Of Expressway Routine Maintenance Performance Management Based On Dea, Li Yuhuan, Shi Xiaoli, Gao Nan

Journal of China & Foreign Highway

To allocate maintenance resources efficiently and improve management levels, this paper examines the maintenance performance and improvement strategies of routine maintenance projects for 23 expressways in Shaanxi Province using 2018 operational maintenance data and data envelopment analysis. The results show that for some inefficient subsidiaries, traditional radial- and slack-based performance improvement methods are challenging and impractical in the short term. Therefore, a scenario-dependent model-based long-term incremental improvement strategy is proposed. By leveraging relative improvement values, this strategy enables phased improvements for inefficient subsidiaries. It provides a feasible approach for subsidiaries to set lower short-term performance improvement targets while achieving gradual …

Increasing Racial Diversity In The North American Plant Phenotyping Network Through Conference Participation Support, David Lebauer, Alexander Bucksch, Jennifer Clarke, Jesse Potts, Sonali Roy

Department of Statistics: Faculty Publications

A key goal of the North American Plant Phenotyping Network (NAPPN) annual conference is to cultivate a new generation of scientists from diverse backgrounds. As part of their effort to diversify the plant phenomics research community, NAPPN acquired funding to cover all attendance costs for participants from historically black colleges and universities (HBCU) for the 2022 annual meeting. Seven award recipients represented the first attendees from HBCUs in the conference’s 6-year history. In this commentary, we report on the impact of the conference awards, including lessons learned, and the future of the award.

An Application Of The Pagerank Algorithm To Ncaa Football Team Rankings, Morgan Majors

Honors Theses

We investigate the use of Google’s PageRank algorithm to rank sports teams. The PageRank algorithm is used in web searches to return a list of the websites that are of most interest to the user. The structure of the NCAA FBS football schedule is used to construct a network with a similar structure to the world wide web. Parallels are drawn between pages that are linked in the world wide web with the results of a contest between two sports teams. The teams under consideration here are the members of the 2021 Football Bowl Subdivision. We achieve a total ordering …

Big Ideas In Sports Analytics And Statistical Tools For Their Investigation, Benjamin S. Baumer, Gregory J. Matthews, Quang Nguyen

Statistical and Data Sciences: Faculty Publications

Sports analytics—broadly defined as the pursuit of improvement in athletic performance through the analysis of data—has expanded its footprint both in the professional sports industry and in academia over the past 30 years. In this article, we connect four big ideas that are common across multiple sports: the expected value of a game state, win probability, measures of team strength, and the use of sports betting market data. For each, we explore both the shared similarities and individual idiosyncracies of analytical approaches in each sport. While our focus is on the concepts underlying each type of analysis, any implementation necessarily …

Movie Recommender System Using Matrix Factorization, Roland Fiagbe

Data Science and Data Mining

Recommendation systems are a popular and beneficial field that can help people make informed decisions automatically. This technique assists users in selecting relevant information from an overwhelming amount of available data. When it comes to movie recommendations, two common methods are collaborative filtering, which compares similarities between users, and content-based filtering, which takes a user’s specific preferences into account. However, our study focuses on the collaborative filtering approach, specifically matrix factorization. Various similarity metrics are used to identify user similarities for recommendation purposes. Our project aims to predict movie ratings for unwatched movies using the MovieLens rating dataset. We developed …

An Analysis Of All-Cause Mortality On Patients With Sickle Cell Disease And Kidney Disease Using Propensity Score Matching, Adam Garrison

Electronic Theses and Dissertations

In this work, we provide an overview of the Cox proportional hazards model for time to event or survival analysis and the notion of propensity score matching to deal with confounding factors. A full analysis is reported in Chapter 2 concerning mortality for in-center dialysis patients with sickle cell disease to demonstrate the application of a general analysis strategy that has some logistical benefits over more traditional approaches to accounting for confounding variables. We also provide some insight and discussions on the challenges and future research questions that will emerge when trying to implement this strategy as a monitoring tool …

Observational Study Of Organisational Responses Of 17 Us Hospitals Over The First Year Of The Covid-19 Pandemic, Esther K. Choo, Matthew Strehlow, Marina Del Rios, Evrim Oral, Ruth Pobee, Andrew Nugent, Stephen C. Lim, Christian Hext, Sarah Newhall, Diana Ko, Srihari V. Chari, Amy Wilson, Joshua J. Baugh, David Callaway, Mucio Kit Delgado, Zoe Glick, Christian J. Graulty, Nicholas Hall, Abdusebur Jemal, Madhav Kc, Aditya Mahadevan, Milap Mehta, Andrew C. Meltzer, Dar'ya Pozhidayeva, Daniel Resnick-Ault

School of Public Health Faculty Publications

Objectives The COVID-19 pandemic has required significant modifications of hospital care. The objective of this study was to examine the operational approaches taken by US hospitals over time in response to the COVID-19 pandemic. Design, setting and participants This was a prospective observational study of 17 geographically diverse US hospitals from February 2020 to February 2021. Outcomes and analysis We identified 42 potential pandemic-related strategies and obtained week-to-week data about their use. We calculated descriptive statistics for use of each strategy and plotted percent uptake and weeks used. We assessed the relationship between strategy use and hospital type, geographic region …

Near-Term Effects Of Perennial Grasses On Soil Carbon And Nitrogen In Eastern Nebraska, Salvador Ramirez Ii, Marty R. Schmer, Virginia L. Jin, Robert B. Mitchell, Kent M. Eskridge

Department of Statistics: Faculty Publications

Incorporating native perennial grasses adjacent to annual row crop systems managed on marginal lands can increase system resiliency by diversifying food and energy production. This study evaluated (1) soil organic C (SOC) and total N stocks (TN) under warm-season grass (WSG) monocultures and a low diversity mixture compared to an adjacent no-till continuous-corn system, and (2) WSG total above-ground biomass (AGB) in response to two levels of N fertilization from 2012 to 2017 in eastern Nebraska, USA. The WSG treatments consisted of (1) switchgrass (SWG), (2) big bluestem (BGB), and (3) low-diversity grass mixture (LDM; big bluestem, Indiangrass, and sideoat …

Inter-Rater Reliability Of Statistics Based On Reconstructed Individual Patient Data From Published Kaplan-Meier Curves, Megan E. Smith

Theses & Dissertations

Introduction: Time-to-event outcomes include two elements: an indicator variable for whether the event has taken place, and the length of time from some origin point to the occurrence of the event of interest. Due to the complexity of these data, secondary analysis methods, such as indirect comparisons and meta-analysis, are easier to perform when individual-level patient data (IPD) is available.

Objectives: In 2021, an R package IPDfromKM was published, which contains an algorithm for reconstructing IPD from a Kaplan-Meier graph. The current research aimed to investigate the reproducibility of the IPDfromKM algorithm.

Methods: Three statisticians (MS, LS, …

Comparing Hierarchical Data Structures And Hierarchical Data Analysis, Halley Jeanne Dante, Robert Rovetti

Honors Thesis

Real world data is inherently noisy and data analysis can be especially complex when noise is compounded in hierarchical and multilevel data structures. Since such data structures can be described using multiple approaches, the way data is collapsed and grouped within these structures can influence its resulting interpretation and analyses. To avoid discrepancies in data collapsing and grouping, multiple statistical approaches have been developed specifically to analyze multilevel data structures. Examples of multilevel statistical models are the two-factor ANOVA and the general linear model with repeated-measures (GLM-RR) which is typically used in the context of looking at change over time. …

Trends In Resources For Neonatal Intensive Care At Delivery Hospitals For Infants Born Younger Than 30 Weeks' Gestation, 2009-2020, Nansi S. Boghossian, Marco Geraci, Ciaran S. Phibbs, Scott A. Lorch, Erika M. Edwards, Jeffrey D. Horbar

Faculty Publications

Importance: In an ideal regionalized system, all infants born very preterm would be delivered at a large tertiary hospital capable of providing all necessary care. Objective: To examine whether the distribution of extremely preterm births changed between 2009 and 2020 based on neonatal intensive care resources at the delivery hospital. Design, Setting, and Participants: This retrospective cohort study was conducted at 822 Vermont Oxford Network (VON) centers in the US between 2009 and 2020. Participants included infants born at 22 to 29 weeks' gestation, delivered at or transferred to centers participating in the VON. Data were analyzed from February to …

Brief Review: Low Frequency Event Charts (G-Charts) In Healthcare, James Espinosa, David Ho, Alan Lucerna, Henry Schuitema

Rowan-Virtua Research Day

The ability to determine if a change in a system is actually an improvement—or worsening in function—is one of the essential desiderata of quality improvement efforts. There are many ways to look at the issue. A special problem occurs when the event being studied is low frequency by nature. By way of example, patient falls in a given hospital or division of a hospital may occur in a way that is low frequency—yet each event is important. Process engineering has developed an approach to low frequency events. Part of this approach may involve specialized charts that look at the “time-between-events”—as …

Formula 101 Using 2022 Formula One Season Data To Understand The Race Results, Christopher Garcia, Oliver Lopez

Student Scholar Symposium Abstracts and Posters

The reason why I am interested in Formula One is that my friend showed me what Formula One was all about. It became interesting to see the action of the sport, including the battles the drivers have during the race and how fast they go through a corner. Also, when qualifying comes around, they push their car to the absolute limit to gain a few seconds off their opponents. The drivers only in the top 10 receive points from the winner getting 25 points, the last driver in the top 10 getting 1 point, and those below the top ten …

A Probabilistic Exploration Of Food Supplementation And Assistance, Logan Mattingly

Honors College Theses

Food insecurity is a stark threat that grips our country and affects households throughout our country. Dietary insufficiency manifests itself in ways that affect health and public safety. According to researchers, individuals who suffer from food insecurity have a higher risk of aggression, anxiety, suicide ideation and depression. These problems tend to occur unequally distributed among those households with lower income. In this work, an exploratory analysis within these data sets will be performed to examine the socio-economic, biographical, nutritional, and geographical principal components of food insecurity among survey participants and how the US Supplemental Nutrition Assistance Program (SNAP) effects …

Fractal Newton Methods, Ali Akgül, David E. Grow

Mathematics and Statistics Faculty Research & Creative Works

We introduce fractal Newton methods for solving (Formula presented.) that generalize and improve the classical Newton method. We compare the theoretical efficacy of the classical and fractal Newton methods and illustrate the theory with examples.

Fully Decoupled Energy-Stable Numerical Schemes For Two-Phase Coupled Porous Media And Free Flow With Different Densities And Viscosities, Yali Gao, Xiaoming He, Tao Lin, Yanping Lin

Mathematics and Statistics Faculty Research & Creative Works

In this article, we consider a phase field model with different densities and viscosities for the coupled two-phase porous media flow and two-phase free flow, as well as the corresponding numerical simulation. This model consists of three parts: a Cahn-Hilliard-Darcy system with different densities/viscosities describing the porous media flow in matrix, a Cahn-illiard-Navier-Stokes system with different densities/viscosities describing the free fluid in conduit, and seven interface conditions coupling the flows in the matrix and the conduit. Based on the separate Cahn-Hilliard equations in the porous media region and the free flow region, a weak formulation is proposed to incorporate the …

An Integer Garch Model For A Poisson Process With Time-Varying Zero-Inflation, Isuru Panduka Ratnayake, V. A. Samaranayake

Mathematics and Statistics Faculty Research & Creative Works

A serially dependent Poisson process with time-varying zero-inflation is proposed. Such formulations have the potential to model count data time series arising from phenomena such as infectious diseases that ebb and flow over time. The model assumes that the intensity of the Poisson process evolves according to a generalized autoregressive conditional heteroscedastic (GARCH) formulation and allows the zero-inflation parameter to vary over time and be governed by a deterministic function or by an exogenous variable. Both the expectation maximization (EM) and the maximum likelihood estimation (MLE) approaches are presented as possible estimation methods. A simulation study shows that both parameter …

Quantifying The Effect Of Socio-Economic Predictors And The Built Environment On Mental Health Events In Little Rock, Ar, Alfieri Ek, Grant Drawve, Samantha Robinson, Jyotishka Datta

Sociology and Criminology Faculty Publications and Presentations

Law enforcement agencies continue to grow in the use of spatial analysis to assist in identifying patterns of outcomes. Despite the critical nature of proper resource allocation for mental health incidents, there has been little progress in statistical modeling of the geo-spatial nature of mental health events in Little Rock, Arkansas. In this article, we provide insights into the spatial nature of mental health data from Little Rock, Arkansas between 2015 and 2018, under a supervised spatial modeling framework. We provide evidence of spatial clustering and identify the important features influencing such heterogeneity via a spatially informed hierarchy of generalized …

A Monte Carlo Analysis Of Nonprobability Sampling & Post Hoc Corrections, Julia Hong

Masters Theses & Specialist Projects

Nonprobability samples are often used in place of probability samples because the former are less trouble and less expensive. Unfortunately, it is difficult to determine how well a sample represents population parameters when using nonprobability samples. Researchers attempt to mitigate the disadvantages of nonprobability sampling by performing post hoc corrections, but this adjustment may not successfully undo the effects of nonprobability sampling. To examine these effects, a Monte Carlo simulation was conducted to create a pseudo-population from which samples were drawn. Forty-one conditions were replicated 10,000 times each, with each sample consisting of 100 observations. A post-stratification adjustment was made …

Identifying And Analyzing Multi-Star Systems Among Tess Planetary Candidates Using Gaia, Katie E. Bailey

Electronic Theses and Dissertations

Exoplanets represent a young, rapidly advancing subfield of astrophysics where much is still unknown. It is therefore important to analyze trends among their parameters to learn more about these systems. More complexity is added to these systems with the presence of additional stellar companions. To study these complex systems, one can employ programming languages such as Python to parse databases such as those constructed by TESS and Gaia to bridge the gap between exoplanets and stellar companions. Data can then be analyzed for trends in these multi-star exoplanet systems and in juxtaposition to their single-star counterparts. This research was able …

Examining Political Discourse On Online 8kun And Reddit Forums, Braden Mindrum

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A recent example of political violence in the United States was that of the January 6, 2021, Capitol attack in connection with the certification of Joseph R. Biden’s victory over Donald J. Trump in the 2020 US presidential election. This thesis analyzes the events of January 6, 2021, through the lens of social media discourse. This thesis presents a workflow that acquired over 5 million 8kun and Reddit posts from various apolitical and political forums in the three months preceding and following the Capitol attack on January 6, 2021. Techniques from text analysis are then used to group forums according …

Investigating The Effect Of Greediness On The Coordinate Exchange Algorithm For Generating Optimal Experimental Designs, William Thomas Gullion

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Design of Experiments (DoE) is the field of statistics concerned with helping researchers maximize the amount of information they gain from their experiments. Recently, researchers have been turning to optimal experimental designs instead of classical/catalog experimental designs. One of the most popular algorithms used today to generate optimal designs is the Coordinate Exchange (CEXCH) Algorithm. CEXCH is known to be a greedy algorithm, which means it tends to favor immediate, locally best designs instead of globally optimal designs. Previous research demonstrated that this tradeoff was efficacious in that it reduced the cost of a single run of CEXCH and allowed …

Subgroup Identification Via Interaction Tree And Mixed Model For Repeated Measures With Application To Alzheimer’S Disease, Zhichen Xu

Arts & Sciences Graduate Student Theses and Dissertations

No abstract provided.

Theoretical And Computational Aspects Of Robust Cluster Analysis For Multivariate And High-Dimensional Datasets, Andrews Tawiah Anum

Open Access Theses & Dissertations

Multivariate and high-dimensional datasets typically contain subgroups that may not be immediately apparent. To reveal these groups, cluster analysis is performed. Cluster analysis is an unsupervised machine learning technique commonly employed to partition a dataset into distinct categories referred to as clusters. The k-means algorithm is a prominent distance-based clustering method. Despite overwhelming popularity, the algorithm is not invariant under non-singular affine transformations and is not robust, i.e., can be unduly influenced by outliers. To address these deficiencies, we propose an alternative model-based clustering procedure by minimizing a “trimmed” variant of the negative log-likelihood function. We develop a “concentration step”, …