Matching Items (4)
Description
A model has been developed to modify Euler-Bernoulli beam theory for wooden beams, using visible properties of wood knot-defects. Treating knots in a beam as a system of two ellipses that change the local bending stiffness has been shown to improve the fit of a theoretical beam displacement function to edge-line deflection data extracted from digital imagery of experimentally loaded beams. In addition, an Ellipse Logistic Model (ELM) has been proposed, using L1-regularized logistic regression, to predict the impact of a knot on the displacement of a beam. By classifying a knot as severely positive or negative, vs. mildly positive or negative, ELM can classify knots that lead to large changes to beam deflection, while not over-emphasizing knots that may not be a problem. Using ELM with a regression-fit Young's Modulus on three-point bending of Douglass Fir, it is possible estimate the effects a knot will have on the shape of the resulting displacement curve.
ContributorsSexton, Thurston Bryant (Author) / Takahashi, Timothy (Thesis director) / Jones, Donald (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Human Evolution and Social Change (Contributor)
Created2015-05
Description
College and university students are heavily influenced by their exposure to opportunities, individuals, and belief-systems during their time in school. More specifically, countless students are impacted by campus Christian ministries. There are 67 registered religious clubs and organizations across Arizona State University's four campuses, and 46 of them identify as Christian. Similar to most faith-based organizations, Christian campus ministries seek to impact the lives of students. This study will take a look at the influence of these ministries at ASU by researching their intersection with another key component of university life: wellness.
The primary research question is, “How does involvement in Christian ministries at ASU relate to the wellness of students?” The study will examine multiple dimensions of wellness: occupational, physical, social, intellectual, spiritual, and emotional. Each component is essential to understanding the health and well-being of an individual, which is why this study will measure wellness levels in each dimension among samples of students at ASU.
The methodology chosen was a short, anonymous survey that 148 ASU students participated in—73 involved in Christian ministries at ASU and 75 not involved. The quantitative component included a wellness assessment using questions from The National Wellness Institute. These wellness scale questions were broken up into 5 randomized sections, each with one question per dimension, for 30 questions total. Each question response was assigned a rating on a 1 to 5 scale, 1 associated with low wellness and 5 high wellness. The qualitative component, comprised of short answer questions, only applied to students who were involved in a Christian ministry. This portion allowed respondents to explain if and how the ministry impacts each dimension of wellness uniquely.
The quantitative results showed some evident differences between students involved in Christian ministries and students not involved. The social and spiritual dimensions concluded much higher levels of wellness for involved students, both statistically significant with p-values of 0.028 and 0.004. Although some of the wellness differences between involved and not involved participants were not statistically significant, there is also notable variation among questions within each dimension. For the qualitative data, most students in Christian ministries said they believe their involvement increases their wellness in all six dimensions. For each dimension, over 75% of participants said that the ministry impacted their well-being. For the social, spiritual, and emotional dimensions, at least 97% of respondents said their ministry involvement impacted their wellness.
In examining the conclusions of the study, one recommendations is to strengthen the partnership between the greater ASU community and Christian ministries by collaborating and combining resources for programming that relates to their common goals and shared values. Additionally, other faith-based organizations at ASU may benefit from replicating this study to observe their unique wellness impact.
The primary research question is, “How does involvement in Christian ministries at ASU relate to the wellness of students?” The study will examine multiple dimensions of wellness: occupational, physical, social, intellectual, spiritual, and emotional. Each component is essential to understanding the health and well-being of an individual, which is why this study will measure wellness levels in each dimension among samples of students at ASU.
The methodology chosen was a short, anonymous survey that 148 ASU students participated in—73 involved in Christian ministries at ASU and 75 not involved. The quantitative component included a wellness assessment using questions from The National Wellness Institute. These wellness scale questions were broken up into 5 randomized sections, each with one question per dimension, for 30 questions total. Each question response was assigned a rating on a 1 to 5 scale, 1 associated with low wellness and 5 high wellness. The qualitative component, comprised of short answer questions, only applied to students who were involved in a Christian ministry. This portion allowed respondents to explain if and how the ministry impacts each dimension of wellness uniquely.
The quantitative results showed some evident differences between students involved in Christian ministries and students not involved. The social and spiritual dimensions concluded much higher levels of wellness for involved students, both statistically significant with p-values of 0.028 and 0.004. Although some of the wellness differences between involved and not involved participants were not statistically significant, there is also notable variation among questions within each dimension. For the qualitative data, most students in Christian ministries said they believe their involvement increases their wellness in all six dimensions. For each dimension, over 75% of participants said that the ministry impacted their well-being. For the social, spiritual, and emotional dimensions, at least 97% of respondents said their ministry involvement impacted their wellness.
In examining the conclusions of the study, one recommendations is to strengthen the partnership between the greater ASU community and Christian ministries by collaborating and combining resources for programming that relates to their common goals and shared values. Additionally, other faith-based organizations at ASU may benefit from replicating this study to observe their unique wellness impact.
ContributorsSouza, Ann Christina (Author) / Golden, Amy (Thesis director) / Valiente, Carlos (Committee member) / Department of English (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / School of Politics and Global Studies (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
In materials science, developing GeSn alloys is major current research interest concerning the production of efficient Group-IV photonics. These alloys are particularly interesting because the development of next-generation semiconductors for ultrafast (terahertz) optoelectronic communication devices could be accomplished through integrating these novel alloys with industry-standard silicon technology. Unfortunately, incorporating a maximal amount of Sn into a Ge lattice has been difficult to achieve experimentally. At ambient conditions, pure Ge and Sn adopt cubic (α) and tetragonal (β) structures, respectively, however, to date the relative stability and structure of α and β phase GeSn alloys versus percent composition Sn has not been thoroughly studied. In this research project, computational tools were used to perform state-of-the-art predictive quantum simulations to study the structural, bonding and energetic trends in GeSn alloys in detail over a range of experimentally accessible compositions. Since recent X-Ray and vibrational studies have raised some controversy about the nanostructure of GeSn alloys, the investigation was conducted with ordered, random and clustered alloy models.
By means of optimized geometry analysis, pure Ge and Sn were found to adopt the alpha and beta structures, respectively, as observed experimentally. For all theoretical alloys, the corresponding αphase structure was found to have the lowest energy, for Sn percent compositions up to 90%. However at 50% Sn, the correspondingβ alloy energies are predicted to be only ~70 meV higher. The formation energy of α-phase alloys was found to be positive for all compositions, whereas only two beta formation energies were negative. Bond length distributions were analyzed and dependence on Sn incorporation was found, perhaps surprisingly, not to be directly correlated with cell volume. It is anticipated that the data collected in this project may help to elucidate observed complex vibrational properties in these systems.
By means of optimized geometry analysis, pure Ge and Sn were found to adopt the alpha and beta structures, respectively, as observed experimentally. For all theoretical alloys, the corresponding αphase structure was found to have the lowest energy, for Sn percent compositions up to 90%. However at 50% Sn, the correspondingβ alloy energies are predicted to be only ~70 meV higher. The formation energy of α-phase alloys was found to be positive for all compositions, whereas only two beta formation energies were negative. Bond length distributions were analyzed and dependence on Sn incorporation was found, perhaps surprisingly, not to be directly correlated with cell volume. It is anticipated that the data collected in this project may help to elucidate observed complex vibrational properties in these systems.
ContributorsLiberman-Martin, Zoe Elise (Author) / Chizmeshya, Andrew (Thesis director) / Sayres, Scott (Committee member) / Wolf, George (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Non-Destructive Testing (NDT) is integral to preserving the structural health of materials. Techniques that fall under the NDT category are able to evaluate integrity and condition of a material without permanently altering any property of the material. Additionally, they can typically be used while the material is in active use instead of needing downtime for inspection.
The two general categories of structural health monitoring (SHM) systems include passive and active monitoring. Active SHM systems utilize an input of energy to monitor the health of a structure (such as sound waves in ultrasonics), while passive systems do not. As such, passive SHM tends to be more desirable. A system could be permanently fixed to a critical location, passively accepting signals until it records a damage event, then localize and characterize the damage. This is the goal of acoustic emissions testing.
When certain types of damage occur, such as matrix cracking or delamination in composites, the corresponding release of energy creates sound waves, or acoustic emissions, that propagate through the material. Audio sensors fixed to the surface can pick up data from both the time and frequency domains of the wave. With proper data analysis, a time of arrival (TOA) can be calculated for each sensor allowing for localization of the damage event. The frequency data can be used to characterize the damage.
In traditional acoustic emissions testing, the TOA combined with wave velocity and information about signal attenuation in the material is used to localize events. However, in instances of complex geometries or anisotropic materials (such as carbon fibre composites), velocity and attenuation can vary wildly based on the direction of interest. In these cases, localization can be based off of the time of arrival distances for each sensor pair. This technique is called Delta T mapping, and is the main focus of this study.
The two general categories of structural health monitoring (SHM) systems include passive and active monitoring. Active SHM systems utilize an input of energy to monitor the health of a structure (such as sound waves in ultrasonics), while passive systems do not. As such, passive SHM tends to be more desirable. A system could be permanently fixed to a critical location, passively accepting signals until it records a damage event, then localize and characterize the damage. This is the goal of acoustic emissions testing.
When certain types of damage occur, such as matrix cracking or delamination in composites, the corresponding release of energy creates sound waves, or acoustic emissions, that propagate through the material. Audio sensors fixed to the surface can pick up data from both the time and frequency domains of the wave. With proper data analysis, a time of arrival (TOA) can be calculated for each sensor allowing for localization of the damage event. The frequency data can be used to characterize the damage.
In traditional acoustic emissions testing, the TOA combined with wave velocity and information about signal attenuation in the material is used to localize events. However, in instances of complex geometries or anisotropic materials (such as carbon fibre composites), velocity and attenuation can vary wildly based on the direction of interest. In these cases, localization can be based off of the time of arrival distances for each sensor pair. This technique is called Delta T mapping, and is the main focus of this study.
ContributorsBriggs, Nathaniel (Author) / Chattopadhyay, Aditi (Thesis director) / Papandreou-Suppappola, Antonia (Committee member) / Skinner, Travis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05