Stander Symposium Projects

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  Adaptive AR-based Yoga System

  Nikesh Chithambaram

  Engaging in high-impact physical activities may not be suitable for individuals with disabilities and senior adults to maintain their fitness needs due to the risk of injury or exacerbating pre-existing conditions. Adaptive yoga provides a low-impact alternative that offers tailored exercises to different age groups and individuals with disabilities. However, post-pandemic travel can make attending yoga sessions challenging. To address this, the augmented-reality based yoga system provides a way to learn and practice yoga in an immersive mixed-reality environment at comfort of comfort of their home or preferred location. The application uses a database of yoga poses and a mixed-reality environment with a virtual instructor to guide users and allow them to interact with both virtual and real-world elements. The application provides different yoga routines based on user details, and live feedback with the help of a smartphone camera to correct and validate yoga poses. Moreover, the application tracks the user's progress and provides digital rewards to motivate them further. The user can also workout with family or friends represented by virtual avatars in a joint yoga session, promoting a sense of community and belonging. Adaptive yoga provides numerous health benefits, including strengthened bones, enhanced balance and flexibility, improved quality of sleep, and reduced stress, depression, and anxiety, promoting mental fitness and clarity for the elderly. The proposed application makes learning yoga engaging and enjoyable while providing various health benefits. Also, the application ensures exercises are practiced correctly and safely with the help of live feedback. The proposed application provides a convenient and accessible solution for post-pandemic times. The social aspect can help promote overall mental health and well-being, enhancing a sense of community and belonging. The proposed application has significant implications for promoting active and healthy aging.

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  Additively Manufactured Deltoid Fillers for Composite T-joints

  Khalid Aldhahri

  Advanced composite materials consist of continuous fibers of carbon or glass embedded in a polymer matrix, such as epoxy. This hybrid material system forms a high-strength and lightweight structure that is increasingly used in a wide variety of applications, including aerospace, marine structure and vehicles, energy production, sporting goods, and general infrastructure. There are numerous manufacturing processes for making these products, but all of them involve combining the matrix with a high concentration of reinforcing fibers, resulting in a highly compacted laminate structure. T-joint composite parts have been widely used in the construction of products in several applications, especially in aerospace. Recently, there has been increased interest in investigating T-joint strength behavior and failure mechanisms through a combination of experimental and numerical approaches. These parts require a filler material in the voided deltoid region, where the base and flange meet, to ensure their strength and damage tolerance. To provide structural integrity, including a filler material in the deltoid region is necessary for finished composite parts. Conventionally, the deltoid region fills up with resin during molding, or a rolled-up piece of fabric is placed in the region prior to molding to reinforce the resin. Neither approach is ideal for several reasons including fiber distortion and uncontrolled permeability in the deltoid region. In this research, a tensile pull-off test is used to investigate the strength of T-joint parts with different custom porosity of 3D printed parts used as the filler material. The maximum force required to fail the structure, as well as the total elongation to failure, were compared for a carbon/epoxy composite T-joint structure.

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  Aerodynamic Study of the Turbulence in the Wake of a 2022 Formula One Car

  Luis Mendez

  For the 2022 Formula One (F1) season, F1 introduced a new set of technical regulations that reduce the complexity of the aerodynamic devices such as the spoiler, often called wings. The objective of this regulation change is to reduce the amount of turbulence produced allowing the cars to trail behind one another closer, making for easier overtaking and increasing the competitiveness of the sport. The present study evaluates and quantifies the aerodynamic performance of a 2022 F1 rear wing by using computational fluid dynamic (CFD) analyses. Both a study of a 2022 and 2021 specification rear wing is assessed to determine how the new technical regulations affect the turbulence in the wake of the car. The study is performed by taking cut planes in the fluid domain downstream of the rear wing model and integrating over the plane to determine the turbulence behind the wing. With this analysis, a comparison between the two rear wing specifications can be performed to determine the magnitude of impact the new technical regulations produce. From this, a conclusion can be made regarding the effectiveness of the 2022 F1 technical regulations, and whether the regulation change was justified.

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  A Factor Based Portfolio Weighing Model for the S&P 500 Health Care Sector (XLV): An Empirical Analysis of Portfolio Returns, 2009-2022

  Nathan Jabaay, Kevin Cullen

  In this study, I use firm revenue growth as my factor weight. I carry out two empirical tests: (1) my revenue growth factor based portfolio weighing model outperforms an equal weight portfolio model over the period 2009-2022; (2) firm revenue growth is a priced-in risk factor in the equity market. For my first test, I compare the long run cumulative returns for the revenue growth factor based portfolio weighing model to the returns for the equal weight portfolio, 2009-2022. For my second test, I determine if my portfolio weighing model generates excess returns over the broad market benchmark, the S&P 500 index, for the period 2009-2022. I use two investment strategies, a buy and hold strategy and an adjustable shares strategy, to generate the returns for my portfolio weighing model.

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  A First-Principles Investigation of the Optical Properties of Two-dimensional Si Thin Films

  Nicholas Saunders

  Recent experimental studies suggest that thin-film crystalline silicon is viable as a high-efficiency material for energy conversion in solar cells. A theoretical study on the optical properties of two-dimensional (2D) silicon thin films is needed to gain insights into the structure-property correlation of this material. In our project, we made Density Functional Theory calculations of multiple 2D silicon thin films of different structures. We first constructed their model structures from bulk silicon by cutting it along the (100), (110), and (111) low-Miller-index faces, varying the number of silicon atomic layers from two to eight layers, and exposing the bare surfaces or terminating them with hydrogen atoms. We then relaxed the atomic coordinates and in-plane lattice vectors of the 2D films. Next, we calculated the surface energies for the thin films with bare surfaces and modelled the octahedral crystal habit of silicon. From electronic structure calculations, we found that the 2D films with bare surfaces possess metallic in-gap states near the Fermi level, whereas hydrogen termination on the surfaces can render semiconducting thin films suitable for optical applications. Finally, we calculated the optical properties of the semiconducting thin films from the complex dielectric function at different levels of approximation, giving frequency-, face-index-, and thickness-dependent absorption coefficients. We found that the absorption coefficients increase with increasing thicknesses, asymptotically approaching that of the bulk structure. Among the three face indices studied, the (111) films have the lowest surface energy and achieve the highest absorption coefficients, making (111) the most favorable face index for thin-film silicon solar cell applications.

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  Africa in the Twenty-First Century

  Jonathan Shepelak, Terrence Oliss, Michael Dimisa, Carson Karn, Benjamin Burkett, Ahmad S GH B Alazemi, Bader S M M M Alotaibi, Mohammad E M M Alazmi, Clara Schulze, Rachel Reid, Miguel Reyes, Makoro Kebe, William Uhlenbrock, Sean Coney, Andrew Koltas, Conner Kelley, David Hughes, Bobbi Gunn, Sheora Watkins, Charles Lynch, Michael Adedokun, Elizabeth Andreu, James Boldt, Bryon Helbling, Alexandra Cooney, Michael Cooney, Mia Huckleberry, Saad M S Z Alazemi, Anthony Rizkallah, Soud M S M Alazmi, Drew Gueterman, Piper Ashley, Alvaro Guerrero Valera, Ace Kinman

  These presentations examine topics which shape contemporary African experience with a goal of introducing the audience to why and how Africa will shape events in the twenty-first century. The topic presented in include infectious diseases, Muammar Gadhafi, Human Trafficking, Blood Diamond, and civil conflict.

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  A Longitudinal Investigation of Sibling Effects on Parent-Child Relationships

  Caleigh Pistorius

  This study examines the relationship between one’s siblings’ internalizing and externalizing problems, and the effect those behaviors may have on one’s relationship with one’s parents. Previous research indicated that siblings’ relationships are some of the most long-lasting and important relationships in an individual’s life. Family research has also shown that there are situations in which children’s internalizing and externalizing behaviors can shape their relationship with their parents. However, no previous research to my knowledge has explored whether one’s sibling’s behaviors influences one’s own parent-child relationship. During this study, data from the United States Department of Labor and National Longitudinal Survey of Youth (NLSY79) as well as the Children of the National Longitudinal Survey of Youth (CNLSY) was analyzed. Internalizing and externalizing behaviors were evaluated through the Behavior Problems Index (BPI). The child’s perception of parenting was evaluated based on four scales: Autonomy, Disharmony, Intimacy, and Joint Activity (Hart et al., 1999). When siblings are further apart in age, there was an association found between internalizing and externalizing behaviors and Joint Activities, resulting in the younger child spending less time with parents. Disharmony between parents and children was found to be only correlated with the child’s own externalizing behaviors, not with a siblings’ externalizing behaviors. These findings do not provide clear support for the possibility that sibling behavior problems have influence on one's own parent-child relationship.

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  American Fracture, Digital Rage: Evaluating the Influence of Conspiratorial Rhetoric on the U.S. Catholic Community

  Dominic Sanfilippo

  It has been well documented that religious individuals and groups continue to play roles in both the complex global web of polarization, extremism, and terroristic violence and in the reciprocal forces of peacebuilding, justice work, and public reconciliation. My graduate thesis research examines the historical antecedents and current characteristics of digital spaces like #CatholicTwitter (and, in particular, the degree to which both conspiratorial and extremist rhetoric flow throughout them) to assess how such social media spaces both mediate the American Catholic experience and affect the civic health of the United States at large. This thesis speaks to all those interested in understanding, assessing, and combatting civic fragmentation, polarization, and extremism; enters into a growing scholarly conversation exploring the various ways Catholic individuals and institutions both affect and are affected by conspiratorial discourse, misinformation, and disinformation; and point toward potential reconciliatory paths forward. As a Catholic and Marianist institution, the University of Dayton "encourages its members to judge for themselves how institutions are performing their purposes (and) to expose deficiencies in their structures and operations..." through inquiry, dialogue, and praxis. In that spirit, I write in hopes of helping advance our campus community's communal mission to function as a university for the common good.

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  A Multi-Sector Portfolio Weighting Model with Firm Revenue Growth the Factor Weight: An Empirical Analysis of Portfolio Returns, 2009-2022

  Daniel Montgomery, Vincent Rullo

  In this study we conduct two empirical tests. First, we determine if the revenue growth factor weighted multi-sector portfolio outperforms an equal weight portfolio over the period 2009-2022. Second, we test to see if revenue growth is a “priced-in risk factor” by determining if the long term returns to our portfolio weighting model are in excess of the returns to the broad market index S&P 500.60 stocks from six S&P 500 sectors make up the portfolio. The six sectors are: (1) Consumer Discretionary, (2) Healthcare, (3) Industrials, (4) Information Technology, (5) Real Estate, and (6) Communication Services. Historically, these six sectors contribute most of the returns to the S&P 500. To generate our returns, we use two investment strategies: (1) Buy and Hold, and (2) Adjustable Shares.

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  Anaerobic propionate exposure and its effect on the pathogenesis of Listeria monocytogenes

  Allison Herceg

  Listeria monocytogenes is a prevalent food-borne pathogen, and a clear understanding of its pathogenesis can enhance our capability to treat infections. L. monocytogenes is ingested through contaminated foods, enters the intestinal lumen, and is able to spread throughout the rest of the body. The intracellular life cycle of L. monocytogenes requires the regulated expressions of a variety of virulence genes. We previously found that exposure to short chain fatty acids (SCFAs), fermentation byproducts present in the intestines, resulted in significant changes in L. monocytogenes pathogenesis. This research, divided into two major projects, aimed to understand the relationship between L. monocytogenes, its host, and the exposure to SCFAs. Project one evaluated the effect of prior anaerobic exposure of SCFAs, specifically propionate, on strain 07PF0776, a cardiotropic clinical isolate. Hemolytic assays were used to measure the activity of secreted LLO as an indication of bacterial virulence. This project also assessed intracellular growth and actin polymerization of L. monocytogenes in cardiac myoblast cells and macrophages. To further investigate the mechanism underlying L. monocytogenes response to SCFAs, project two explored the role of CodY, a transcription factor in response to levels of branched chain amino acids, in the opposing effects of propionate on LLO production. By comparing the culture supernatant LLO activities in strain 10403s and a mutant with a codY gene deletion (ΔcodY), I discovered that CodY was required for the increase in LLO production in response to anaerobic propionate exposure. Together, the results of these projects provide further evidence for the relationship between SCFA exposure and L. monocytogenes pathogenesis. Ultimately, these findings can be utilized to improve the understanding of L. monocytogenes and develop effective prevention and treatment methods.

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  Analysis of IMDB Movie Ratings, with Emphasis on User Predictions and Recommendations

  Reed Shay

  The Movies Dataset, available on Kaggle, is a comprehensive dataset containing information on movies released between 1990 and 2017. In this project, we aim to analyze variables that have significant predictive power on the success of a movie and to build a recommendation system based on users' profiles.Firstly, we will explore the dataset and preprocess it to extract relevant information for our analysis. We will then perform exploratory data analysis to identify potential predictors of a movie's success, such as budget, genre, runtime, release date, and rating. We will use regression techniques to model the relationship between these predictors and a movie's success, as measured by box office revenue and user ratings. The results of our analysis will provide insights into the factors that contribute to a movie's commercial and critical success.In the second part of the project, we will develop a recommendation system that suggests movies to users based on their preferences. We will incorporate content-based filtering techniques, where we analyze the movie's features and recommend movies that are similar in genre, cast, or storyline to those the user has previously enjoyed. This can be a tricky problem as movie ratings are often times purely subjective and highly variable.Overall, this project will provide a comprehensive analysis of the movies dataset and a recommendation system that can help users discover new movies that match their preferences.

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  Analysis of Large-Scale Diabetic Retinopathy using Deep Convolutional Neural Network

  M M Shaifur Rahman

  Deep learning (DL) is currently one of the most popular branch of Machine Learning and uses Deep Convolutional Neural Network (DCNN) architectures. It can transform medical diagnostics. DCNN predictions are significantly dependent on high-quality input data. However, large-scale images are challenging to operate with classical deep-learning architectures due to their vast memory and computational requirements. Currently, one of the popular approaches to deal with large-scale input images is to resize the large image to a smaller dimension which decays the performance of the overall system. Another popular approach to overcome large-scale image problems is to sequentially crop the high-resolution image into multiple smaller images to fit in the computation memory (GPU). In this work, we demonstrate a novel approach to training and inference in higher-resolution input images (e.g., 1024 x 1024) with DCNN. Our proposed architectures are constructed with state-of-the-art DCNN backbone models such as ResNet101, DenseNet-121 and EfficientNet. Finally, the models are evaluated using large-scale diabetic retinopathy datasets (e.g., Dataset for Diabetic Retinopathy, Kaggle 2019 BD). The experimental results are compared against existing deep learning methods and demonstrate significant improvements in accuracy.

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  Analysis of Power System Resilience Subject to Extreme Events

  Adedayo Aruwajoye

  The purpose of this study is to increase the understanding of power system resilience through pattern recognition of disaster-induced system disruption. This study consists of analyzing power system failure and recovery patterns in a post-extreme event environment to determine relevant pattern characteristics relating to power system resilience. Specifically, the methodology of this study consists of (1) collecting and processing data from power system failures induced by natural disasters categorized by power companies, states, counties, and natural disaster occurrence.; (2) developing failure and recovery curves for the collected data; (3) investigating and establishing statistical distribution models that correlate to the goodness of fit for plotted curves best characterizing the system behaviour for each extreme external occurrence; and (4) creating a quantitative algorithm for specifying the resilience of such engineered systems. The resultant algorithm will assist in answering questions about the resiliency of power systems. Since modern society relies extensively on power systems to survive, this increased insight into power system resilience will provide better situational awareness for stakeholders during future decision-making discussions regarding power system construction.

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  Analyzing the Efficiency of Roller Coaster Block Systems

  Kyle Cullen

  What keeps roller coasters safe? Why do you so rarely ever hear about roller coaster trains colliding? The answer is simple: blocking systems. A block is a section of track only one train may occupy at one time; at the end of each block is a method of stopping and holding a train reliably should the next block not be clear. Examples of this are chain lift hills, magnetic brakes paired with drive tires, or friction brakes that clamp onto a brake fin secured to the bottom of the train. For my project, I would like to design a simple logic system that utilizes proximity sensors to prevent trains from colliding with each other. Along with the sensors, I will be using other miniature versions of common roller coaster components and design a simple track layout for the trains to follow.

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  An anisotropic transfer matrix approach to profiled optical field propagation through hyperbolic metamaterials

  Guo Chen

  We extend the transfer matrix method to study the propagation of beams and arbitrary profiled fields through anisotropic metamaterial slabs, and to demonstrate the negative refractive index property resulting in linear self-focusing of beams in hyperbolic metamaterials. Specifically, the transfer matrix method, commonly used to analyze bi-directional plane wave propagation, is developed to analyze beam propagation. By expressing a Gaussian beam as an angular spectrum of plane waves, an anisotropic transfer matrix, which is also obtained using the eigenvalues mentioned above, can be applied to calculate the beam spectrum at an arbitrary distance of propagation through a hyperbolic metamaterial. With given incident and emergent media, say, air, linear self-focusing within the metamaterial slab and subsequent reimaging in the emergent medium are numerically investigated for one transverse dimensional TM polarized Gaussian beam. Simulation results are compared with results from the unidirectional transfer function approach. The anisotropic transfer matrix method can be used to study beam transmission and reflection at the interfaces, and can be applied to analyze optical propagation through anisotropic metamaterial on uniaxial electro-optic substrates. The technique can be extended to arbitrary initial optical field profiles in one transverse dimension to assess the imaging quality of metamaterial slabs.

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  A New Class of Multinary Copper Chalcogenides for Photovoltaic Applications

  Sohini Sengupta (presenting author); other authors: Fajer A. Almanea, Venkateswar Rao, Jinchen Han, Soubantika Palchoudhury (faculty advisor)

  Cu3MX4 (M = V, Nb, and Ta; X = S, Se, and Te) compounds, also known as the sulvanite family, have recently emerged as promising materials for optoelectronic devices, including solar photovoltaics (PV) due to their tunable band gaps, high optical absorption coefficients and composition consisting of comparatively earth-abundant elements. These several nanocrystal compositions of the Cu3VS4−xSex (x = 0, 1, 2, 3) series were synthesized in the solution phase. The solution-phase synthesis methods allow for the control of particle size and morphology, which conventional solid-state synthesis fails to achieve. Based on experimental band gap characterization via ultraviolet visible spectroscopy,the multinary Copper vanadium chalcogenides possess an intermediate band (IB), making them promising candidates for the absorber layer in solar PV. The optical direct band gap trend shows a decrease with increasing Se content. The IB solar cells are designed to incorporate an energy band that is partially filled with electrons within the forbidden bandgap of a semiconductor, in order to provide a large photogenerated current while maintaining a high output voltage. A detailed material characterization of these new multinary nanocrystals was conducted using x-ray diffraction, photoluminescence spectroscopy, and scanning electron microscopy to further understand the structure-property relation of these nanocrystals.

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  A New Long Wavelength BODIPY Probe for Protein Binding

  Amy Hess

  A new single molecule 4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyedesigned to conjugate to the peripheral amines of proteins have been synthesized. Thesynthetic route taken toward these dyes along with their characterization by 1 H NMR willbe described. This dye offers extraordinary absorption and emission properties withinthe far-visible region of the electromagnetic spectrum. Details of their spectroscopicproperties along with first attempts to conjugate this dye to proteins will be presented.

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  An Exploration of the Grid Game Connect Four

  Peter Maris

  Connect Four is a popular game in which two players take turns placing game chips down an upright six-by-seven grid. The goal is to get four chips in a line (vertically, horizontally, or diagonally). Connect Four has been extensively studied and it has been determined that the player who moves first has an advantage. We studied an upright three-by-three grid in which the objective is to get three chips in a line. We also considered other games on three-by-three grids such as Tic-Tac-Toe and Dawson’s Chess.

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  Animal Crossing: The Intersection of Roads and Wildlife

  Samantha Soucie, Elizabeth Vear, Matthew Carroll, Megan Tierney

  While animal activity vastly differs across trophic levels, many animals share the same consequences of altering their behaviors and habitats due to human activity. Man-made constructs can dramatically alter natural animal movements, where some animals may use them to their own benefit. One example of this is that some species of birds have found that they can perch along power lines providing them safety from the threat of ground predators. We tested the hypothesis that larger animals will travel along the old roads in a reclaimed urban park more often than smaller animals who will tend to stay in the more wooded areas of the park. To test this hypothesis, we set out 10 trail cameras within the Environmental Research Area at Old River Park with 5 along old roads and 5 set up within the wooded areas of the park. We will monitor animal activity by going through the pictures taken by the cameras to see which types of animals are found more on the paved paths compared to the wooded areas. We expect that our hypothesis will be supported that larger animals will be using the paved paths more frequently than the smaller animals who will prefer to stay in the wooded areas. This finding can indicate that animals are adapting their activity to use the human created environment around them for their own benefit. These larger animals don't necessarily depend on the paved paths to be able to move around, but it may make it easier to travel around as invasive species like honeysuckle are quickly taking up all of the free space within the forest floor.

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  An Investigation of the Mechanics of an Ultra-Stretchable, Self-Healing, DLP 3D-Printed Hydrogel for Damage-Resistant Soft Robots

  Joshua Michonski (presenter); other authors: Joseph Beckett, Carl Thrasher, Braeden Windham, Allyson Cox, Timothy Osborn, Anesia Auguste, Robert Lowe, and Christopher Crouse

  Inspired by nature, soft robots composed of compliant (“soft”) materials are well-suited for uncertain, dynamic tasks requiring safe interaction between a robot and its environment. Vat photopolymerization (VP) additive manufacturing (AM) processes such as digital light processing (DLP) have disrupted traditional manufacturing of soft devices, enabling the fabrication of soft robotic components with unprecedented speed, resolution, and complexity. Concurrently, the rapid development of novel self-healing photo-curable soft materials for VP-based AM has paved the way for soft robots with embedded healing of damage (e.g., perforations, tears) induced, for instance, by an unintended interaction with a sharp object in their operating environment. At present, however, the mechanical behavior (deformation and fracture) of self-healing photo-curable soft materials (elastomers and hydrogels) used for next-generation soft robots is not well understood. To address this compelling research opportunity, this work focuses on the design and execution of a mechanical testing program to characterize BeckOHflex, a novel self-healing photo-curable hydrogel synthesized using off-the-shelf chemicals. The large-strain elasticity of BeckOHflex is investigated through quasi-static uniaxial tension testing. Both virgin and self-healed mechanical properties are shown to be commensurate or superior to the best-performing self-healing hydrogels in the literature. Further, a suite of demonstration prints produced on a commercial VP 3D printer highlight the material’s scalability and the ability to yield prints with complex form factors.

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  An IOT-based Temperature Monitoring of cold substances

  Usha Sankalamaddi

  In this project I will build an IOT-based temperature monitoring of cold substances. It is achieved using the Adafruit circuit playground express and circuitpython. I am trying to monitor the temperatures of the cold substances in celsius and fahrenheit as well. I have chosen this project to explore more about the working of sensors and implementing them in real time.

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  A Novel Approach for User-Centric Privacy Protection on the Web

  Satish Kumar Oad

  Every day, we see the number of web-based applications rapidly increase. These programs are run within the web browser, where they interact with a variety of user-provided data. The use of web scripts, particularly JavaScript, which accesses this information through a set of APIs offered by the browser, is what gives web applications their dynamism. A sizable number of web-based attacks that violate users' security and privacy have been discovered over the past ten years. Attackers can steal your personal information by using some scripting language or other web attacks like cross-site scripting, SQL injections etc. Nowadays many websites are using the third-party API’s without checking the code and scanning vulnerabilities, that API’s can take advantage of security vulnerabilities and steal the user information without knowing the user like user cookies, session and if got any secret cookie or session id of user then they can harm the user data. There are many extensions which can block all the things but these are not able to ask the user what content the user wants to see in the browser before starting the web application. We have created a number of policy categories, put in place a policy engine to enforce these regulations, and given users a graphical interface to modify these policies in accordance with their needs. Our test findings showed that the framework enables end-users to alter the rules and regulate how device resources are used. Our policy enforcement engine firmly prohibits the simulated attack scenarios, preventing the misuse of device resources and user privacy

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  A Novel, Efficient Approach for Determining the Post-Necking True Stress-Strain Response of Aerospace Metals

  Yatik Rashmin Shah

  To numerically simulate and predict the plastic deformation of aerospace metals and alloys during extreme impact events (e.g., turbine engine blade-out and rotor-burst events, bird strikes, and foreign object damage), accurate knowledge of the metal’s hardening behavior at large strains is requisite. Tensile tests on round cylindrical specimens are frequently used for this purpose, with the metal’s large-strain plasticity ultimately captured by a true stress vs. true plastic strain curve. During tensile testing, the strain field in the specimen gage section evolves from a nearly homogeneous profile prior to necking to a heterogeneous profile after the onset of necking. Concomitantly, the customary analytical relationships used to convert between engineering stress-strain and true stress-strain break down after necking, since the state of stress is no longer homogeneous or uniaxial after necking. Thus, a number of approaches have been proposed and employed to correct the post-necking hardening response. Although effective, these approaches are generally complex and/or computationally expensive, which can be particularly problematic for large experimental programs. In this talk, a novel and efficient post-necking correction method is proposed and benchmarked. Using the equivalent true strain history obtained from a digital image correlation virtual strain gage placed at the fracture location, an approximate first-order analytical approach is used to calculate the corresponding equivalent true stress. This true stress calculation is used to generate a simple post-necking hardening law, using linear interpolation between known true stress-strain states at necking and fracture. This approach is successfully benchmarked using experimental data from a suite of metals with different crystal structures and hardening behavior: Inconel 625, Inconel 718, 17-4 precipitation hardening (PH) stainless steel, and Ti-6Al-4V titanium alloy.

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  Anti-predator Behavior in Response to Conspecific Visual, Olfactory, and Damage Cues in the Three-spined Stickleback

  Claire Van Meter

  Predation is a major source of mortality for prey, which creates a selective pressure forbeing able to avoid predators whenever possible. By using alarm cues produced by conspecifics,organisms can be alerted of nearby predators without coming in direct contact with them.However, we do not know whether individuals can distinguish between different kinds ofconspecific cues and if some types of cues may indicate a more severe predation threat comparedto others. Three-spined stickleback (Gasterosteus aculeatus) are used as a model for behavioralstudies because their defense responses have been well studied and identified, and they areknown to respond to both predatory and conspecific visual and olfactory cues. I studied theability of the three-spined stickleback to distinguish between environmental cues by exposingconspecifics to four different types of conspecific alarm cues: cues of predator-naïveconspecifics (control water with unexposed demonstrator), visual cues of predator-exposed conspecifics (control water with predator-exposed demonstrator), visual and conspecificolfactory cues (stress cues and predator-exposed demonstrator), and visual, conspecific olfactory,and conspecific damage cues (stress cues, damage cues, and predator-exposed demonstrator). For 5 minutes before and after exposure to the cues, I watched for four key defensive behaviors:hiding in plants, hiding in the gravel at the bottom of the tank, swimming into the walls of thetank, and shoaling. I assayed 40 conspecifics over 8 weeks, for a total of 160 trials. Directly after each assay, I placed the focal subject in 200ml of RO water in a 600ml beaker for 1 hour to collect waterborne cortisol. I will run this water through ELISA assays to measure the cortisol concentration in the sample. I hypothesize that the conspecifics will be able to distinguish between the severity of the cues, causing an increase in anti-predator behavior response in exposure to all the combined cues in comparison to a few, or none of the cues. I anticipate that through this research, we will gain a better understanding of the influence of conspecific communication, specifically regarding how conspecifics interpret olfactory and visual conspecific cues. Anti-predator behavior is often costly, so being able to determine when such behavior is necessary based on conspecific communication could be a key factor in the survival and success of species.

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  A Numerical Solution of Coupled Drinfeld-Sokolov-Wilson System Using Meshless Method of Lines

  Ibrahim Guediri

  For this project, we reproduce the meshless method of lines numerical solution of coupled Drinfeld-Sokolov-Wilson system. This method uses radial basis functions (RBFs) for spatial collocation. Time integration of the resulting system of ODEs will be solved using fourth order of Runge-Kutta method. Accuracy will be compared with the results from other methods available in the literature.