Digital Commons Network^™

On High Pressure Real Gas Turbulent Mixing Jets, Neelakantan Padmanabhan

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A database of direct numerical simulation (DNS) of spatially evolving turbulent mixing slot jets of Heptane-Air and Heptane-Oxygen is developed. The formulation includes the compressible form of the governing equations, a generalized multicomponent diffusion model with Soret and Dufour effects, a cubic real gas equation of state and realistic property models. Simulations are conducted over a wide range of initial pressures (1 atm < P0 < 100 atm) and jet width based Reynolds numbers of 850 and 1300. High order explicit finite difference schemes in combination with low order boundary closures and Runge-Kutta time integration schemes are used to approximate the spatial and temporal derivatives. Non-reflecting inflow and outflow boundary conditions in combination with absorbing zones are applied for proper convection of flow structures and acoustic waves with minimal reflection of numerical waves. Low level disturbances are imposed on the laminar inflow near the nozzle to initiate instability for development of turbulence. The simulations are run until a statistically stationary state of the flow is achieved. The mean velocity, variance, centerline velocity excess decay, and downstream growth of normal Reynolds stresses are calculated and compared with various experimental results. For subgrid analysis, a spatial filtering operation is applied to the DNS. The filtered mass density function (FMDF) of mixture fraction at various filter widths is obtained from the simulation at several spatial locations within the flow. The conditional scalar diffusion (CSD) term in the exact transport equation of FMDF is calculated from the DNS. A parametric study of variation of CSD with time, spatial location, Reynolds number, pressure and diffusion models is conducted. An a priori analysis of Interaction by Exchange of Mean (IEM), Modified Curl (MC) and Mapping Closure (MAPPING) mixing models for CSD is conducted. Performance of mixing models at various pressures with the generalized and Fickian diffusion models, with real and ideal gas equations of state is evaluated. The significance of mixing frequency used in the models and the errors associated with calculation of mixing frequency in simulations with the generalized diffusion model is studied. A parametric study of variation of the mixing frequency and its parameters with pressures, diffusion models and Reynolds number is performed. New model constants for mixing frequency applicable to the LES with generalized diffusion models at various pressures are proposed. Conditionally averaged mixing frequency for the IEM model is determined and compared with the conditionally averaged second invariant of the strain tensor to study the effects of flow physics (viscous dissipation) on the mixing time. Mean turbulent kinetic energy and mean dissipation rates are calculated from the DNS and their ratios are compared with mixing frequencies at various pressures. The model constants for various pressures are determined and an alternative expression for determination of mixing frequency in LES with generalized diffusion models is proposed. The budget equation for the Reynolds stress tensor in the compressible RANS momentum equation is derived. The terms of the budget equation (convection, diffusion, pressure-strain, production, dissipation and compressibility) are calculated directly from the DNS at various pressures. The most significant terms in the budget that require modeling are determined to be diffusion and pressure-strain terms. Existing models for diffusion and pressure-strain terms are evaluated over a large range of pressures with the DNS data. At fixed Mach and Reynolds numbers, the models are determined to be dependent on the ambient pressure. New modeling constants for various models over a large range of pressures are proposed.

Assessment Of South Carolina's Department Of Transportation (Scdot's) Readiness To Perform Data Driven Safety Assessments, Hind A. Ali

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Under MAP-21 federally mandated requirements, the Moving Ahead for Progress in the 21st Century (MAP-21), South Carolina is implementing a data-driven based safety decisions and roadway safety performance, which is highly evaluated based on the assessment of safety related information including roadway, traffic, and crash data. Roadway characteristics and Traffic data in most case a subset of the Model Inventory Management System (MIRE) version 1.0 for roadway and traffic data, or from Minimum Model Uniformity Crash Criteria (MMUCC) for crash data. For all that, this thesis involves analyzing and investigating the state-of the-practice and the state-of-the-art of the current SCDOT …

Joule Heating Enabled Electrokinetic Trapping Of Submicron Particles In Ratchet Microchannels Using Depth Modelling, Abhinav Kalkhanda

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Microfluidic devices have been increasingly used for diverse particle manipulations in various chemical and biological applications. Fields such as water quality control, environmental monitoring and food safety require the continuous trapping and concentration of particles (either bio- or non-bio) for enhanced detection and analysis. To achieve this, various microfluidic techniques have been developed using electric field as well as other fields including magnetic, optical, acoustic, hydrodynamic, gravitational and inertial. Among these methods, electrokinetic manipulation of particles is the most often used due to its advantages over other methods such as simple operation and easy integration etc. It transports fluids and …

Undergraduate And Teaching Assistants"™ Perceptions Of Classroom Community In Freshman Biological Sciences Laboratories And Implications For Persistence And Professional Development, Andrew Kardohely

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The American economy hinges on the health and production of science, technology engineering and mathematics workforce (STEM). Although this sector of the American workforce represents a substantially fewer jobs the STEM workforce fuels job growth and sustainability in the other sectors of the American workforce. Unfortunately, over the next decade the U.S. will face an additional deficit of over a million STEM professionals, thus the need is here now to fill this deficit. STEM education should, therefore, dedicated to producing graduates. One strategy to produce more STEM graduates is through retention of student in STEM majors. Retention or persistence is …

Multi-Stability And Variable Stiffness Of Cellular Solids Based On Origami Patterns, Sattam Sengupta

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The application of origami patterns in engineering design has been the subject of much research efforts. Structures derived based on origami patterns are capable of displaying a host of innovative mechanical properties which are directly related to the kinematics of their folding. The work presented in this research takes design inspiration from a rigid foldable type of origami, namely the Miura-ori pattern. A cellular solid designed based on the Miura Ori folding pattern can exhibit three dimensional multi-stability, and different programmable characteristics like variable stiffness and elastic moduli, which stem from the inherent elastic multi-stability. The Miura Ori structure can …

X-Map A Performance Prediction Tool For Porting Algorithms And Applications To Accelerators, Ashrit Shetty

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Most modern high-performance computing systems comprise of one or more accelerators with varying architectures in addition to traditional multicore Central Processing Units (CPUs). Examples of these accelerators include Graphic Processing Units (GPU) and Intel’s Many Integrated Cores architecture called Xeon Phi (PHI). These architectures provide massive parallel computation capabilities, which provide substantial performance benefits over traditional CPUs for a variety of scientific applications. We know that all accelerators are not similar because each of them has their own unique architecture. This difference in the underlying architecture plays a crucial role in determining if a given accelerator will provide a significant …

Preferential Flow Systems Amended With Biogeochemical Components: Imaging Of A Two-Dimensional Study, Ashley Rose Pales

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The rhizosphere is the region of soil directly impacted by a plants roots, both physically (root growth) and chemically (water and nutrient uptake via organic compounds). The chemical components exuded by a plants roots can be lumped into two categories; mucilage and exudates. Mucilage effects on flow have been widely studied, though the independent effects of exudates have not. The objective of this research is to investigate the effects of plant root exudates on the infiltration processes through a porous media. This is done by (1) characterizing the solid-liquid and liquid-gas interfaces of the exudate solutions used for the flow …

Understanding Teacher Effectiveness With Complexity And Network Theories, Xiaoyan (Gemma) Jiang

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This study seeks to understand teacher effect on student test scores with perspectives from complexity and network theories. The assumptions are that network relationships and interactive dynamics are important to individual productivity in knowledge intensive organizations such as schools. Data were collected from students, faculty and staff in ten elementary schools in one school district in the southeast US. The analytical framework included: network analyses, hierarchical linear modeling, Lenth's analysis, response surface methodology and multiple regression. Results support the assumptions. Teacher's network measures exhibited complex linear, curvilinear and interactive effects on student test scores. Teachers who are central in the …

Clemson Commencement Program, August 2017, Clemson University

Clemson Commencement Programs

No abstract provided.

A Holistic Investigation And Implementation Of Fluidic Origami Cellular Solid For Morphing And Actuation, Hrishikesh Sane

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Engineering applications of origami are gaining momentum in the recent decades. These applications range from nano-scale biomedical devices to large architectural and aerospace structures. Motivated by the rich kinematic behavior due to folding, the concept of fluidic origami was proposed as a versatile actuator. The idea is to seal deformable cylinders based on the origami patterns and apply pressure to achieve shape morphing and actuation. However, previous research relied on an idealistic kinematic model, which assumes that origami facets are rigid and have zero thickness so that the folding deformation is concentrated at the hinge-like creases. To address this issue, …

Orbital Angular Momentum For Underwater Wireless Optical Communications, Joshua Adams Baghdady

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Upon its discovery in 1992, the Orbital Angular Momentum of light, or OAM, catalyzed the development of an entire field of photonics research aimed at exploring the capabilities of this newfound phenomenon. Since then, scientists have put OAM to work in fields as diverse as imaging, particle manipulation, encryption, and communications. Although the focus of much work in this latter field in the area of free space optical communications, before this research OAM had never before been tested as a communication mechanism underwater. In this work, the use of OAM for optical communications is first motivated from a physical and …

Deep Multimodal Fusion Networks For Semantic Segmentation, Jesse Tetreault

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Deep Convolutional Neural Networks (CNN) have emerged as the dominant approach for solving many problems in computer vision and perception. Most state-of-the-art approaches to these problems are designed to operate using RGB color images as input. However, there are several settings that CNNs have been deployed in where more information about the state of the environment is available. Systems that require real-time perception such as self-driving cars or drones are typically equipped with sensors that can offer several complementary representations of the environment. CNNs designed to take advantage of features extracted from multiple sensor modalities have the potential to increase …

Integrating Parametric Structural Analysis And Optimization In The Architectural Schematic Design Phase, Nixon Wonoto

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The implementation of computational form-finding structural optimization methods has recently mushroomed in the architectural research area. There has been a few emerging architectural parametric Computer-Aided Design (CAD) systems that enable architects to perform early schematic form-finding structural optimization such as the coupling of Grasshopper (a visual programming language), Karamba (a structural analysis plugin) and Galapagos (an optimization plugin). However, the application of the method is very rare in both educational and design practice environments. Also, the architectural schematic design phase is commonly characterized by free-form shapes without the embedded considerations of the material and structural system. On the other hand, …

Modeling And Analysis Of Remote, Off-Grid Microgrids, Sreenath Chalil Madathil

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Over the past century the electric power industry has evolved to support the delivery of power over long distances with highly interconnected transmission systems. Despite this evolution, some remote communities are not connected to these systems. These communities rely on small, disconnected distribution systems, i.e., microgrids, to deliver power. Power distribution in most of these remote communities often depend on a type of microgrid called "off-grid microgrids''. However, as microgrids often are not held to the same reliability standards as transmission grids, remote communities can be at risk to experience extended blackouts. Recent trends have also shown an increased use …

Exploring The Role Of Simulation And Visualization Tools In Improving Learning Outcomes In Support Of Technology Programs, Melissa Isabel Zelaya-Floyd

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Online educational opportunities have provided students with the flexibility to advance their careers and complete certificate and degree programs. These have also provided educational institutions with increased capacity without the investment of costly brick-and-mortar expansions at campuses. Technology programs, however, have shied away from integrating these advances due to their program outcomes being heavily dependent on the use of tools and hands-on learning. This dissertation explores the use of digital learning lectures on linear measuring instruments accompanied with virtual reality tools in technology programs and its effects on both cognitive and psychomotor learning outcomes compared to current modality - face-to-face …

Multiscale Regional Liquefaction Hazard Assessment And Mapping, Chaofeng Wang

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Soil liquefaction is a major cause of damage during earthquakes that could trigger many kinds of ground failures such as ground settlement, lateral spreading, land slides, etc. These ground failures could cause damage to infrastructures such as buildings, bridges, and lifelines resulting in significant economic losses. Therefore it is of significant importance to assess liquefaction hazard. The triggering and consequencing ground failure of liquefaction have been well investigated in the past decades. Nowadays, the dominant approach that correlates the observed field behavior with various in-situ "œindex" tests is able to achieve considerably precise assessments for free field conditions at site-specific …

Discretizations & Efficient Linear Solvers For Problems Related To Fluid Flow, Ryan R. Grove

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Numerical solutions to fluid flow problems involve solving the linear systems arising from the discretization of the Stokes equation or a variant of it, which often have a saddle point structure and are difficult to solve. Geometric multigrid is a parallelizable method that can efficiently solve these linear systems especially for a large number of unknowns. We consider two approaches to solve these linear systems using geometric multigrid: First, we use a block preconditioner and apply geometric multigrid as in inner solver to the velocity block only. We develop deal.II tutorial step-56 to compare the use of geometric multigrid to …

Evaluating The Effects Of Immersive Embodied Interaction On Cognition In Virtual Reality, Dhaval Parmar

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Virtual reality is on its advent of becoming mainstream household technology, as technologies such as head-mounted displays, trackers, and interaction devices are becoming affordable and easily available. Virtual reality (VR) has immense potential in enhancing the fields of education and training, and its power can be used to spark interest and enthusiasm among learners. It is, therefore, imperative to evaluate the risks and benefits that immersive virtual reality poses to the field of education. Research suggests that learning is an embodied process. Learning depends on grounded aspects of the body including action, perception, and interactions with the environment. This research …

Exact Algorithms For Mixed-Integer Multilevel Programming Problems, Leonardo Lozano

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We examine multistage optimization problems, in which one or more decision makers solve a sequence of interdependent optimization problems. In each stage the corresponding decision maker determines values for a set of variables, which in turn parameterizes the subsequent problem by modifying its constraints and objective function. The optimization literature has covered multistage optimization problems in the form of bilevel programs, interdiction problems, robust optimization, and two-stage stochastic programming. One of the main differences among these research areas lies in the relationship between the decision makers. We analyze the case in which the decision makers are self-interested agents seeking to …

Adaptive Robust Methodology For Parameter Estimation And Variable Selection, Tao Yang

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The dissertation consists of three distinct but related projects. We consider regression model fitting, variable selection in regression, and autocorrelation estimation in time series. In each procedure we formulate the problem in terms of minimizing an objective function which adapts to the given data. First we propose a robust M-estimation procedure for regression. The main purpose of the proposed methodology is to develop a procedure that adapts to light/heavy tailed, symmetric/asymmetric distributions with/without outliers. We focus on studying the properties of the maximum likelihood estimator of the asymmetric exponential power distribution, a broad distribution class that holds both Normal and …

Turkish Pre-Service Secondary Mathematics Teachers: An Examination Of Tpack, Affect, And Their Relationship, Ercan Dede

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Pre-service teachers' knowledge, beliefs or attitudes gained during their undergraduate education is one of the most influential factors shaping their future teaching in their field. Technological Pedagogical Content Knowledge framework (TPACK; Mishra & Koehler, 2006) identifies the knowledge domains needed by teachers to effectively integrate technology into teaching their field. Due to the fact that pre-service teachers' TPACK domains cannot be directly measured, most of research studies in the literature addressed developing a TPACK survey instrument in order to indirectly measure teachers' TPACK in terms of their perceptions. However, there were rare research studies focusing on development a TPACK survey …

Connections Between Future Time Perspectives And Self-Regulated Learning For Mid-Year Engineering Students: A Multiple Case Study, Justine Chasmar

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This dissertation presents multiple studies with the purpose of understanding the connections between undergraduate engineering students' motivations, specifically students' Future Time Perspectives (FTPs) and Self-Regulated Learning (SRL). FTP refers to the views students hold about the future and how their perceptions of current tasks are affected by these views. SRL connects the behaviors, metacognition, and motivation of students in their learning. The goals of this research project were to 1) qualitatively describe and document engineering students' SRL strategies, 2) examine interactions between engineering students' FTPs and SRL strategy use, and 3) explore goal-setting as a bridge between FTP and SRL. …

Radio-Frequency Sensors For Detection And Analysis Of Chemical And Biological Substances, Yan Cui

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Dielectric spectroscopy (DS) is an important technique for scientific and technological investigations in various areas. DS sensitivity and operating frequency ranges are critical for many applications, including lab-on-chip development where sample volumes are small with a wide range of dynamic processes to probe. In this dissertation, the design and operation considerations of radio-frequency (RF) interferometers that are based on power-dividers (PDs) and quadrature-hybrids (QHs) is presented. The effective quality factor (Qeff) of the sensor is as high as ∼3.8×10^6 with 200 μL of water samples. Such interferometers are proposed to address the sensitivity and frequency tuning challenges of current DS techniques. …

Laboratory Evaluation Of Natural And Enhanced Remediation Of Chlorinated Ethenes In Fractured Sandstone, Rong Yu

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Chlorinated ethenes are common industrial chemicals and among the most frequently detected groundwater contaminants. Behavior and remediation of chlorinated ethenes in unconsolidated aquifers composed of granular materials (e.g., sand, silt and gravel) has been extensively studied for several decades. Nevertheless, it was not until the end of twentieth century that the role of matrix diffusion in plume persistence gained widespread acceptance. Matrix diffusion commonly occurs in complicated hydrogeological settings such as fractured sedimentary bedrock aquifers, where the permeable fractures act as the major conduit for groundwater flow and the less permeable but high capacity matrix acts as the primary storage …

Balancing And Sequencing Of Mixed Model Assembly Lines, Anas Alsayed Alghazi

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Assembly lines are cost efficient production systems that mass produce identical products. Due to customer demand, manufacturers use mixed model assembly lines to produce customized products that are not identical. To stay efficient, management decisions for the line such as number of workers and assembly task assignment to stations need to be optimized to increase throughput and decrease cost. In each station, the work to be done depends on the exact product configuration, and is not consistent across all products. In this dissertation, a mixed model line balancing integer program (IP) that considers parallel workers, zoning, task assignment, and ergonomic …

Understanding The Relationship Between Performance Characteristics, Shot Selection And Decision-Making In The Game Of Tennis, Dotan Israel Shvorin

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In order to improve tennis player performance, we first need to investigate the features of performance that define a tennis player. This research begins with a focus on understanding how performance errors occur in the game. Over a span of two years, data were collected and analyzed in order to demonstrate the impact of various performance characteristics on the player's capability. The outcome of this work was twofold. The research has been employed by the Clemson University tennis program to design improved training drills. The research has also been used to form a baseline for making decisions at the management …

Essays On Flood Disaster Relief Recovery Practices And Policy: Applying The Lens Of Service Operations Strategy, Niratcha Tungtisanont

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This dissertation uses a service operations lens to investigate flood disasters’ recovery phase, the least-studied area of Humanitarian Operations and Crisis Management (HOCM). Comprising three essays, my dissertation deepens our knowledge of disaster recovery by using two different units of analysis, including province (state) and household levels.

In Essay 1, entitled “The Influence of Industrialization and Internet Usage on Per-Capita Income: A Longitudinal Analysis of Flood Events in Thai Provinces,” we introduce a novel approach to research HOCM by using econometric analyses. We use panel data as a tool to guide decision makers in understanding the notion of flood recovery, …

Time-Dependent Stokes-Darcy Flow With Deposition, Javier Ruiz Ramirez

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This thesis investigates two nonlinear systems of time-dependent partial differential equations that model a filtration process. Existence and uniqueness results for the governing equations is established. For each system, a finite element scheme capable of approximating the solutions is investigated. Accompanying numerical experiments corroborate the analytical findings. Finally, an optimization application concerning the design of a filter is discussed and supported with a numerical study.

Johnson-Lindenstrauss Transformations, Fiona Knoll

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With the quick progression of technology and the increasing need to process large data, there has been an increased interest in data-dependent and data-independent dimension reduction techniques such as principle component analysis (PCA) and Johnson\-Lindenstrauss (JL) transformations, respectively. In 1984, Johnson and Lindenstrauss proved that any finite set of data in a high-dimensional space can be projected into a low-dimensional space while preserving the pairwise Euclidean distance within any desired accuracy, provided the projected dimension is sufficiently large; however, if the desired projected dimension is too small, Woodruff and Jayram, and Kane, Nelson, and Meka in 2011 separately proved such …

Evaluation And Uncertainty Quantification Of Vs30 Models Using A Bayesian Framework For Better Prediction Of Seismic Site Conditions, Andrew West Brownlow

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The time-averaged shear-wave velocity in the top 30 meters of subsurface material (VS30) is a widely used parameter when estimating the potential for amplification of seismic waves. Situations often arise where a design VS30 value needs to be chosen from multiple proxy-based VS30 models. This dissertation seeks to assist with the problem of model selection and to improve the overall prediction of VS30 through implementation of a Bayesian framework for model ranking. Furthermore, this dissertation investigates the effects of uncertainty on the model ranking results. In this work, probabilistic methods are developed and implemented to assess the performance of multiple …