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Description
Despite the established co-prevalence of substance use (SU) and disordered eating (DE), few longitudinal studies have sought to examine their shared development. Findings have been inconsistent within the extant literature. This may be attributable in part to several methodological aspects, including overlooking distinct psychopharmacological properties of common substances of abuse, examining only between-person relations, and failing to account for shared risk factors. The current study sought to address these gaps by applying latent curve models with structured residuals (LCM-SR) to a preexisting, national sample of adolescent girls followed into adulthood, Add Health. In Aim 1, between-person effects examined the simultaneous development of alcohol, tobacco, and marijuana use and DE behaviors in substance-specific models. In Aim 2, bivariate latent curve models were expanded to account for within-person effects (LCM-SR) in order to examine the potentially bidirectional, prospective relationship between use of a specific substance and DE. Lastly, models accounted for shared developmental risk factors. Findings of the current study demonstrate preliminary evidence of substance-specific effects with DE emerging in adolescence. Across model-building steps, DE engagement in early adolescence was significantly associated with growth in tobacco use and marginally associated with marijuana use. Appetitive side-effects of both substances may link use with DE behaviors and enhance instrumental use for weight control. Significant associations did not emerge between alcohol and DE, and results of the conditional model indicate this co-occurrence is best explained by third variable mechanisms. Implications for prevention are discussed.
ContributorsBruening, Amanda B (Author) / Corbin, William (Thesis advisor) / Chassin, Laurie (Committee member) / Meier, Madeline (Committee member) / McNeish, Daniel (Committee member) / Arizona State University (Publisher)
Created2021
Description
Accurate knowledge and understanding of thermal conductivity is very important in awide variety of applications both at microscopic and macroscopic scales. Estimation,however varies widely with respect to scale and application. At a lattice level, calcu-lation of thermal conductivity of any particular alloy require very heavy computationeven for a relatively small number of atoms. This thesis aims to run conventionalmolecular dynamic simulations for a particular supercell and then employ a machinelearning based approach and compare the two in hopes of developing a method togreatly reduce computational costs as well as increase the scale and time frame ofthese systems. Conventional simulations were run using interatomic potentials basedon density function theory-basedab initiocalculations. Then deep learning neuralnetwork based interatomic potentials were used run similar simulations to comparethe two approaches.
ContributorsDabir, Anirudh (Author) / Zhuang, Houlong (Thesis advisor) / Nian, Qiong (Committee member) / Jiao, Yang (Committee member) / Arizona State University (Publisher)
Created2021
Description
Additively Manufactured Thin-wall Inconel 718 specimens commonly find application in heat exchangers and Thermal Protection Systems (TPS) for space vehicles. The wall thicknesses in applications for these components typically range between 0.03-2.5mm. Laser Powder Bed Fusion (PBF) Fatigue standards assume thickness over 5mm and consider Hot Isostatic Pressing (HIP) as conventional heat treatment. This study aims at investigating the dependence of High Cycle Fatigue (HCF) behavior on wall thickness and Hot Isostatic Pressing (HIP) for as-built Additively Manufactured Thin Wall Inconel 718 alloys. To address this aim, high cycle fatigue tests were performed on specimens of seven different thicknesses (0.3mm,0.35mm, 0.5mm, 0.75mm, 1mm, 1.5mm, and 2mm) using a Servohydraulic FatigueTesting Machine. Only half of the specimen underwent HIP, creating data for bothHIP and No-HIP specimens. Upon analyzing the collected data, it was noticed that the specimens that underwent HIP had similar fatigue behavior to that of sheet metal specimens. In addition, it was also noticed that the presence of Porosity in No-HIP specimens makes them more sensitive to changes in stress. A clear decrease in fatigue strength with the decrease in thickness was observed for all specimens.
ContributorsSaxena, Anushree (Author) / Bhate, Dhruv (Thesis advisor) / Liu, Yongming (Committee member) / Kwon, Beomjin (Committee member) / Arizona State University (Publisher)
Created2021
Description
Anecdotally, native Mandarin speakers have difficulty distinguishing between the “s” (as in sink) and the “th” (as in think) sounds as well as between the “a” (as in dad) and “ea” (as in dead) sounds. Here, 29 native English speakers, 52 native Mandarin speakers who live in China, and 34 native Mandarin speakers who have been living in an English language dominant environment were recruited to serve as participants. To assess the phoneme contrasts that may occur in native Mandarin speakers in China, and possible improvement in native Mandarin speakers living in an English environment, relative to Native English speakers living in America, a phoneme discrimination test was administered, three paired phonemes were used in the current study: /b/ paired with /p/ as a control pair, /æ/ paired with /ɛ/, and /θ/ paired with /s/. The results showed that native English speakers have significantly higher accuracy rates for the three paired phoneme discrimination tasks than the native Mandarin speakers who live in China. But there was no significant difference between the native English speakers and native Mandarin speakers who have lived in an English environment on the phonemes or words discriminations tasks.
ContributorsChen, Hao (Author) / Nanez, Jose (Thesis advisor) / Horne, Zachary (Thesis advisor) / Holloway, Steven (Committee member) / Arizona State University (Publisher)
Created2021
Description
In the development of autonomous ground vehicles (AGVs), how to guarantee vehicle lateral stability is one of the most critical aspects. Based on nonlinear vehicle lateral and tire dynamics, new driving requirements of AGVs demand further studies and analyses of vehicle lateral stability control strategies. To achieve comprehensive analyses and stability-guaranteed vehicle lateral driving control, this dissertation presents three main contributions.First, a new method is proposed to estimate and analyze vehicle lateral driving stability regions, which provide a direct and intuitive demonstration for stability control of AGVs. Based on a four-wheel vehicle model and a nonlinear 2D analytical LuGre tire model, a local linearization method is applied to estimate vehicle lateral driving stability regions by analyzing vehicle local stability at each operation point on a phase plane. The obtained stability regions are conservative because both vehicle and tire stability are simultaneously considered. Such a conservative feature is specifically important for characterizing the stability properties of AGVs.
Second, to analyze vehicle stability, two novel features of the estimated vehicle lateral driving stability regions are studied. First, a shifting vector is formulated to explicitly describe the shifting feature of the lateral stability regions with respect to the vehicle steering angles. Second, dynamic margins of the stability regions are formulated and applied to avoid the penetration of vehicle state trajectory with respect to the region boundaries. With these two features, the shiftable stability regions are feasible for real-time stability analysis.
Third, to keep the vehicle states (lateral velocity and yaw rate) always stay in the shiftable stability regions, different control methods are developed and evaluated. Based on different vehicle control configurations, two dynamic sliding mode controllers (SMC) are designed. To better control vehicle stability without suffering chattering issues in SMC, a non-overshooting model predictive control is proposed and applied. To further save computational burden for real-time implementation, time-varying control-dependent invariant sets and time-varying control-dependent barrier functions are proposed and adopted in a stability-guaranteed vehicle control problem.
Finally, to validate the correctness and effectiveness of the proposed theories, definitions, and control methods, illustrative simulations and experimental results are presented and discussed.
ContributorsHuang, Yiwen (Author) / Chen, Yan (Thesis advisor) / Lee, Hyunglae (Committee member) / Ren, Yi (Committee member) / Yong, Sze Zheng (Committee member) / Zhang, Wenlong (Committee member) / Arizona State University (Publisher)
Created2021
Description
Inspired by the design of lightweight cellular structures in nature, humans have made cellular solids for a wide range of engineering applications. Cellular structures composed of solid and gaseous phases, and an interconnected network of solid struts or plates that form the cell's edges and faces. This makes them an ideal candidate for numerous energy absorption applications in the military, transportation, and automotive industries. The objective of the thesis is to study the energy-absorption of multi-material cellular structures. Cellular structures made from Acrylonitrile-Butadiene-Styrene (ABS) a thermoplastic polymer and Thermoplastic Polyurethane (TPU) a thermoplastic elastomer were manufactured using dual extrusion 3D printing. The surface-based structures were designed with partitions to allocate different materials using Matlab and nTopology. Aperiodicity was introduced to the design through perturbation. The specimens were designed for two wall thicknesses - 0.5mm and 1mm, respectively. In total, 18 specimens were designed and 3D printed. All the specimens were tested under quasi-static compression. A detailed analysis was performed to study the energy absorption metrics and draw conclusions, with emphasis on specific energy absorbed as a function of relative density, efficiency, and peak stress of the specimens to hypothesize and validate mechanisms for observed behavior. All the specimens were analyzed to draw comparisons across designs.
ContributorsVarma, Rajeshree Pawan (Author) / Bhate, Dhruv (Thesis advisor) / Shuaib, Abdelrahman (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2021
Description
Many medical procedures, like surgeries, deal with the physical manipulation of sensitive internal tissues. Over time, new medical tools and techniques have been developed to improve the safety and efficacy of these procedures. Despite the leaps and bounds of progress made up to the present day, three major obstacles (among others) persist, bleeding, pain, and the risk of infection. Advances in minimally invasive treatments have transformed many formerly risky surgical procedures into very safe and highly successful routines. Minimally invasive surgeries are characterized by small incision profiles compared to the large incisions in open surgeries, minimizing the aforementioned issues. Minimally invasive procedures lead to several benefits, such as shorter recovery time, fewer complications, and less postoperative pain. In minimally invasive surgery, doctors use various techniques to operate with less damage to the body than open surgery. Today, these procedures have an established, successful history and promising future. Steerable needles are one of the tools proposed for minimally invasive operations. Needle steering is a method for guiding a long, flexible needle through curved paths to reach targets deep in the body, eliminating the need for large incisions. In this dissertation, we present a new needle steering technology: magnetic needle steering. This technology is proposed to address the limitations of conventional needle steering that hindered its clinical applications. Magnetic needle steering eliminates excessive tissue damage, restrictions of the minimum radius of curvature, and the need for a complex nonlinear model, to name a few. It also allows fabricating the needle shaft out of soft and tissue-compliant materials.
This is achieved by first developing an electromagnetic coil system capable of producing desired magnetic fields and gradients; then, a magnetically actuated needle is designed, and its effectiveness is experimentally evaluated. Afterward, the scalability of this technique was tested using permanent magnets controlled with a robotic arm.
Furthermore, different configurations of permanent magnets and their influence on the magnetic field are investigated, enabling the possibility of designing a desired magnetic field for a specific surgical procedure and operation on a particular organ. Finally, potential future directions towards animal studies and clinical trials are discussed.
ContributorsIlami, Mahdi (Author) / Marvi, Hamid (Thesis advisor) / Berman, Spring (Committee member) / Lee, Hyunglae (Committee member) / Nikkhah, Mehdi (Committee member) / Sugar, Thomas (Committee member) / Arizona State University (Publisher)
Created2021
Description
Multiphase flows are relevant to various industrial processes and are also a ubiquitous feature of nature. Atomization is a Gas-Liquid class of multiphase flow in which the liquid bulk disintegrates into a spectrum of drops. The final drop size distribution of fragmenting liquids is important and is crucial to quantifying the performance of atomizers. This thesis implements two models of ligament breakup. The first model provides a method to determine the droplet size distribution of fragmenting ligaments. The second model provides a relation between ligament stretching, aspect ratio and dimensionless properties like Ohnesorge and Weber numbers for ligaments being stretched by aerodynamic force. The first model by Villermaux et.al considers a ligament as a linear succession of liquid blobs which undergo continuous interplay during destabilization. The evolution of their size distribution ultimately rules the droplet size distribution which follow a gamma distribution [14]. The results show that the Direct Numerical Simulations (DNS) of ligaments with different perturbations fragmented into very few drops and cannot be used to confirm that they follow the predicted gamma distribution. The second model considers a ligament breakup due to Rayleigh-Plateau Instability and provides an equation for ligament stretching. Through test runs the proportionality constant in the equation is determined by a least square fit. The theoretical number of drops is compared with the number of drops resulting from the Direct Numerical Simulation of ligament with a sinusoidal perturbation. It is found that the wavelength of the initial perturbation does not determine the number of drops obtained by ligament breakup
ContributorsRama Krishna, Prathyush (Author) / Herrmann, Marcus (Thesis advisor) / Takahashi, Timothy (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2021
Description
This thesis lays down a foundation for more advanced work on bipeds by carefully examining cart-inverted pendulum systems (CIPS, often used to approximate each leg of a biped) and associated closed loop performance tradeoffs. A CIPS is characterized by an instability (associated with the tendency of the pendulum to fall) and a right half plane (RHP, non-minimum phase) zero (associated with the cart displacement x). For such a system, the zero is typically close to (and smaller) than the instability. As such, a classical PK control structure would result in very poor sensitivity properties.It is therefore common to use a hierarchical inner-outer loop structure. As such, this thesis examines how such a structure can be used to improve sensitivity properties beyond a classic PK structure and systematically tradeoff sensitivity properties at the plant input/output. While the instability requires a minimum bandwidth at the plant input, the RHP zero imposes a maximum bandwidth on the cart displacement x.
Three CIPs are examined – one with a long, short and an intermediately sized pendulum. We show that while the short pendulum system is the most unstable and requires the largest bandwidth at the plant input for stabilization (hardest to control), it also has the largest RHP zero. Consequently, it will permit the largest cart displacement x-bandwidth, and hence, one can argue that the short pendulum system is easiest to control. Similarly, the long pendulum system is the least unstable and requires smallest bandwidth at the plant input for stabilization (easiest to control). However, because this system also possesses the smallest RHP zero it will permit the smallest cart displacement x-bandwidth, and hence, one can argue that the long pendulum system is the hardest to control. Analogous “intermediate conclusions” can be drawn for the system with the “intermediately sized” pendulum. A set of simple academic examples (growing in plant and controller complexity) are introduced to illustrate basic tradeoffs and guide the presentation of the trade studies.
ContributorsSarkar, Soham (Author) / Rodriguez, Armando (Thesis advisor) / Berman, Spring (Thesis advisor) / Marvi, Hamidreza (Committee member) / Arizona State University (Publisher)
Created2021
Description
This study aimed to develop a measurement model for executive function (EF) in middle childhood for a low-income Mexican American sample and to elucidate dynamic change processes among measurable developmental correlates of EF during infancy and early toddlerhood as predictors of later higher-order EF abilities. Drawing from developmental theory and a model of neurovisceral integration, surges in neurocognitive regulatory abilities may be supported by both previous and concurrent changes in physiological functioning and engagement in reciprocal social relationships. Utilizing recent methodological innovations, the current study moved beyond traditional growth models to evaluate possible points of attenuation and acceleration in dyadic reciprocity and vagal functioning over time as well as dynamic associations between these unfolding developmental processes. Data were collected from 322 low-income Mexican American children in the home at 24 weeks and in a laboratory space at ages 1, 1.5, 2, 3, and 6 years. A parent-report measure of executive function also was collected over the phone between child age 7.5 and 9 years. Results suggested that, in this sample, EF was best modeled at child age 6 years as a unidimensional construct. Findings also supported the importance of earlier dyadic reciprocity for later EF, but there was a lack of evidence supporting the theorized link between EF and earlier vagal functioning and codevelopment of vagal functioning and dyadic reciprocity. This study highlights the importance of including dyadic measures of parent-child contingencies in studies of EF development and, from a clinical perspective, the potential use of relationship-based, dyadic intervention and prevention models to support crucial development of EF skills central to everyday adaptive functioning.
ContributorsWinstone, Laura (Author) / Luecken, Linda J (Thesis advisor) / Spinrad, Tracy (Committee member) / O'Rourke, Holly (Committee member) / Friedman, Lauren (Committee member) / Arizona State University (Publisher)
Created2022