Digital Commons Network^™

Care-Chair: Opportunistic Health Assessment With Smart Sensing On Chair Backrest, Rakesh Kumar

Masters Theses

"A vast majority of the population spend most of their time in a sedentary position, which potentially makes a chair a huge source of information about a person's daily activity. This information, which often gets ignored, can reveal important health data but the overhead and the time consumption needed to track the daily activity of a person is a major hurdle. Considering this, a simple and cost-efficient sensory system, named Care-Chair, with four square force sensitive resistors on the backrest of a chair has been designed to collect the activity details and breathing rate of the users. The Care-Chair system …

Effect Of Sparse-Build Internal Structure On Performance Of Fused Deposition Modeling Parts, Shixuan Meng

Masters Theses

"Fused deposition modeling (FDM) technology has been used in additive manufacturing for years and is able to significantly reduce both manufacturing time and cost for production tooling and end-use parts. Autoclave molding is one of the conventional tools used to produce composite parts. In autoclave molding, the soft composite material is positioned on the molding tool, and then subjected to vacuum and elevated temperatures to facilitate the curing of the resin. With additive manufacturing (AM), it is possible to fabricate the molding tool with a sparse internal structure, thereby reducing the fabrication time and cost compared to a solid tool. …

A Meta-Architecture Analysis For A Coevolved System-Of-Systems, George Anthony Muller Iv

Masters Theses

"Modern engineered systems are becoming increasingly complex. This is driven in part by an increase in the use of systems-of-systems and network-centric concepts to improve system performance. The growth of systems-of-systems allows stakeholders to achieve improved performance, but also presents new challenges due to increased complexity. These challenges include managing the integration of asynchronously developed systems and assessing SoS performance in uncertain environments.

Many modern systems-of-systems must adapt to operating environment changes to maintain or improve performance. Coevolution is the result of the system and the environment adapting to changes in each other to obtain a performance advantage. The complexity …

A Cost Benefit Analysis Of Sst Based Volt-Var Control, Guruprasad Ramani

Masters Theses

"The overall objective of this thesis work is to improve system power quality with the help of solid state transformers (SSTs). Two methods to improve the system power quality are explored: a) achieving a unity power factor at all the load buses, and b) improving the system voltage profile to meet a desired voltage regulation requirement of 0.95

Numerical Analysis Of Flexural Slip During Viscoelastic Buckle Folding, Davi Rodrigues Damasceno

Masters Theses

"Flexural slip is considered to be an important folding mechanism contributing in the development of different folds such as chevron, and kink-band buckle folds. Various filed studies have provided a general conceptual and qualitative understanding of flexural slip. However, quantitative evidence of the importance of the flexural slip mechanism during fold evolution is sparse, as the actual amount of surface parallel displacement, and timing, is difficult to measure accurately, due to the lack of suitable strain markers.

In this study 2D finite element analysis is used to overcome these disadvantages and to simulate flexural slip during viscoelastic buckle folding. Variations …

Thermal Characterization Of Phase Change Materials For Thermal Energy Storage, Rami Mohammad Reda Saeed

Masters Theses

"The study provides a valuable and useful database for Phase Change Materials (PCMs) for Thermal Energy Storage (TES) applications. Only a few existing studies have provided an overall investigation of thermophysical properties of PCMs in this detailed manner. Several organic PCMs, namely Myristic acid, Capric Acid, Lauryl Alcohol, Palmitic acid and Lauric acid, have been characterized after being carefully selected to cover wide range of TES applications. Insights and information gained from this work will be applied toward the design and modelling of many low temperature thermal energy storage applications. The study experimentally investigated uncertainty of thermal characterization of PCMs …

On The Double Chain Ladder For Reserve Estimation With Bootstrap Applications, Larissa Schoepf

Masters Theses

"To avoid insolvency, insurance companies must have enough reserves to fulfill their present and future commitment-refer to in this thesis as outstanding claims towards policyholders. This entails having an accurate and reliable estimate of funds necessary to cover those claims as they are presented. One of the major techniques used by practitioners and researchers is the single chain ladder method. However, though most popular and widely used, the method does not offer a good understanding of the distributional properties of the way claims evolve. In a series of recent papers, researchers have focused on two potential components of outstanding claims, …

Evaluation Of Ultra-High Performance Concrete (Uhpc) In Joints Of Bridge Girders, Saipavan Rallabhandhi

Masters Theses

"Joints are often considered as the weak link in a structure and often deterioration of the structure initiates from the joints. Joints transfer the stresses from super-structure to sub-structure and in this process are subjected to large transfer stresses. Not much attention is given to the design of joints as they are positioned in low moment regions and typically a 4 to 6 ksi (28 to 41 MPa) concrete is used to fill the joints. One of the solution to this problem is Ultra-high performance concrete (UHPC). In the recent past significant research has been done to use UHPC in …

Yik Yak Posts: A Discourse Analysis, Snehal Ravindra Shirke

Masters Theses

"Anonymity and geolocation create a unique environment for users to communicate with each other. Discourse analysis was conducted to study the posts made on Yik Yak, an anonymous social networking mobile application to understand the communication patterns on an anonymous platform and the posts about taboo topics. The posts were analyzed specifically for patterns on taboo topics and how students interact on the anonymous platform on a particular campus (Missouri S&T campus). Student research assistants coded the collected posts into the pre-defined taboo categories namely sexual activity, non-sexual bodily functions, sexual orientation, mental/emotional health, and "other" taboo topics. I found …

Nonlinear Model And Qualitative Analysis For Coupled Axial/Torsional Vibrations Of Drill String, Fushen Ren, Baojin Wang, Suli Chen, Zhigang Yao, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A nonlinear dynamics model and qualitative analysis are presented to study the key effective factors for coupled axial/torsional vibrations of a drill string, which is described as a simplified, equivalent, flexible shell under axial rotation. Here, after dimensionless processing, the mathematical models are obtained accounting for the coupling of axial and torsional vibrations using the nonlinear dynamics qualitative method, in which excitation loads and boundary conditions of the drill string are simplified to a rotating, flexible shell. The analysis of dynamics responses is performed by means of the Runge-Kutta-Fehlberg method, in which the rules that govern the changing of the …

Pre-College Engineering Activities With Electronic Circuits (Work-In-Progress), Steve Eugene Watkins

Electrical and Computer Engineering Faculty Research & Creative Works

Projects involving engineering experimentation, design, and measurement can be effective content for pre-college STEM outreach. Such applications-oriented activities can promote literacy and interest in technical topics and careers and have the added benefit of showing the relevance of science and mathematics. Exposure to electrical engineering concepts is discussed using the 555 timer integrated circuit. This low-cost device can be used for modular activities involving the production of light, sound, and motion. Specific projects are presented that are appropriate for pre-college students from 9th-grade through 12th-grade.

Estimating Freeway Travel Times Using The General Motors Model, Shu Yang, Yaojan Wu, Zhaozheng Yin, Yiheng Feng

Computer Science Faculty Research & Creative Works

Travel time is a key transportation performance measure because of its diverse applications. Various modeling approaches to estimating freeway travel time have been well developed due to widespread installation of intelligent transportation system sensors. However, estimating accurate travel time using existing freeway travel time models is still challenging under congested conditions. Therefore, this study aimed to develop an innovative freeway travel time estimation model based on the General Motors (GM) car-following model. Since the GM model is usually used in a microsimulation environment, the concepts of virtual leading and virtual following vehicles are proposed to allow the GM model to …

Strain Distribution And Crack Detection In Thin Unbonded Concrete Pavement Overlays With Fully Distributed Fiber Optic Sensors, Yi Bao, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study aims at evaluating the feasibility of strain measurement and crack detection in thin unbonded concrete pavement overlays with pulse prepump Brillouin optical time domain analysis. Single-mode optical fibers with two-layer and three-layer coatings, respectively, were applied as fully distributed sensors, their performances were compared with analytical predictions. They were successfully protected from damage during concrete casting of three full-scale concrete panels when 5 to 10-cm-thick protective mortar covers had been set for 2 h. Experimental results from three-point loading tests of the panels indicated that the strain distributions measured from the two types of sensors were in good …

Approximation For Single-Channel Multi-Server Queues And Queuing Networks With Generally Distributed Inter-Arrival And Service Times, Carlos Roberto Chaves

Doctoral Dissertations

"This dissertation is divided into two papers. The first paper is related to developing a closed-form approximation for single-channel multiple-server queues with generally distributed inter-arrival and service times, which are often found in numerous settings, e.g., airports and manufacturing systems. Unfortunately, exact models for such systems require distributions for the underlying random variables. Further, data for fitting distributions is sometimes not available, and one only has access to means and variances of the underlying input random variables. Under heavy traffic, excellent approximations already exist for this purpose. In the first paper, a new approximation method for medium traffic is presented. …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Innovative Techniques For Seismic-Resistant Bridge Columns Under Ground Motion Excitations, Ayman A. Moustafa

Doctoral Dissertations

“This dissertation provides innovative alternative solutions for replacing conventional reinforced concrete columns. The proposed columns displayed enhanced seismic resistance and properties compared to their counterpart conventional columns. Two main techniques were followed and proposed to develop seismic-resistant columns. The first technique utilized rubberized concrete to internally enhance energy dissipation and damping. Materials testing of rubberized concrete with scrap tire replacement of fine aggregates were performed to evaluate its dynamic properties. Shaking table testing of a rubberized concrete column was performed and the behavior was compared to that of the conventional one. The rubberized column showed an increase of 16% in …

Repetitive Process Control Of Additive Manufacturing With Application To Laser Metal Deposition, Patrick M. Sammons

Doctoral Dissertations

"Additive Manufacturing (AM) is a set of manufacturing processes which has promise in the production of complex, functional structures that cannot be fabricated with conventional manufacturing and the repair of high-value parts. However, a significant challenge to the adoption of additive manufacturing processes to these applications is proper process control. In order to enable closed-loop process control compact models suitable for control design and for describing the layer-by-layer material addition process are needed. This dissertation proposes a two-dimensional modeling and control framework, with an application to a specific metal-based AM process, whereby the deposition of the current layer is affected …

Multi-Level Evolutionary Algorithms Resource Allocation Utilizing Model-Based Systems Engineering, Bhanuchander Reddy Poreddy

Doctoral Dissertations

"This research presents an innovative approach to solve the resource allocation problems using Multi-level Evolutionary Algorithms. Evolutionary Algorithms are used to solve resource allocation problems in different domains and their results are then incorporated into a higher level system solution using another Evolutionary Algorithm to solve base camp planning problems currently faced by the U.S. Department of Defense.

Two models are introduced to solve two domain specific models: a logistics model and a power model. The logistic model evaluates routes for logistics vehicles on a daily basis with a goal of reducing fuel usage by delivery trucks. The evaluation includes …

Thorium-Based Mixed Oxide Fuel In A Pressurized Water Reactor: A Feasibility Analysis With Mcnp, Lucas Powelson Tucker

Doctoral Dissertations

"This dissertation investigates techniques for spent fuel monitoring, and assesses the feasibility of using a thorium-based mixed oxide fuel in a conventional pressurized water reactor for plutonium disposition. Both non-paralyzing and paralyzing dead-time calculations were performed for the Portable Spectroscopic Fast Neutron Probe (N-Probe), which can be used for spent fuel interrogation. Also, a Canberra ³He neutron detector's dead-time was estimated using a combination of subcritical assembly measurements and MCNP simulations. Next, a multitude of fission products were identified as candidates for burnup and spent fuel analysis of irradiated mixed oxide fuel. The best isotopes for these applications were …

Liposomal Delivery Of Pde5 Inhibitors And Ut-15c To Human Erythrocytes, Elizabeth Anne Bowles

Doctoral Dissertations

"Previous studies have shown that the controlled release of adenosine triphosphate (ATP) from human erythrocytes is an important mechanism for the regulation of vascular caliber. However, erythrocytes from patients with pulmonary arterial hypertension (PAH) fail to release ATP in response to the physiological stimuli of exposure to low oxygen tension or mechanical deformation of a magnitude these cells would encounter in the pulmonary circulation. This defect could be a significant contributor to the increased pulmonary vascular resistance (PVR) that is the cause of the pathological increase in vascular pressures in humans with PAH.

One important approach to the treatment of …

Polyacrylamide And Its Derivatives For Oil Recovery, Zun Chen

Doctoral Dissertations

"Polyacrylamide is an umbrella term used to describe the homo-polymer of acrylamide and the copolymer of acrylamide with a small amount of other monomers. Owing to their superior property on increasing viscosity and gelling ability in the presence of crosslinkers, polyacrylamides has become the primarily selection for polymer flooding and gel treatment agent in enhanced oil recovery. Recent developments, performance, applications and limitations of polyacrylamides and its derivatives, including copolymers and hydrogels for enhancing oil recovery are reviewed.

A water-free suspension system was developed to synthesize PAMs and PAMs-microgel. Products are dry particle powder and ready to disperse in water. …

Electrodeposition And Characterization Of Metals And Metal Oxides For Energy Conversion And Storage, Ying-Chau Liu

Doctoral Dissertations

"This dissertation investigates the electrodeposition of metal and metal oxide thin films applicable to solar water splitting cells. Paper I describes the synthesis of cobalt hydroxide, ß-Co(OH)₂, by electrochemically reducing tris(ethylenediamine)cobalt(III) in alkaline solution. Paper II presents a scheme to convert the ß-Co(OH)₂ to CoOOH and Co₃O₄ and compares their catalytic activity for the oxygen evolution reaction. Co₃O₄ appears to be a more active catalyst than CoOOH based on Tafel analysis. However, when the observed current densities are corrected for the measured electrochemically active surface area, the linear region of the …

Evaluating Of Scale-Up Methodologies Of Gas-Solid Spouted Beds For Coating Triso Nuclear Fuel Particles Using Advanced Measurement Techniques, Neven Y. Ali

Doctoral Dissertations

"The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking …

Clustering: Methodology, Hybrid Systems, Visualization, Validation And Implementation, Dao Minh Lam

Doctoral Dissertations

"Unsupervised learning is one of the most important steps of machine learning applications. Besides its ability to obtain the insight of the data distribution, unsupervised learning is used as a preprocessing step for other machine learning algorithm. This dissertation investigates the application of unsupervised learning into various types of data for many machine learning tasks such as clustering, regression and classification. The dissertation is organized into three papers. In the first paper, unsupervised learning is applied to mixed categorical and numerical feature data type to transform the data objects from the mixed type feature domain into a new sparser numerical …

Design, Fabrication, Operation And Aspen Simulation Of Oil Shale Pyrolysis And Biomass Gasification Process Using A Moving Bed Downdraft Reactor, Hassan Golpour

Doctoral Dissertations

"Energy is the major facilitator of the modern life. Every developed and developing economy requires access to advanced sources of energy to support its growth and prosperity. Declining worldwide crude oil reserves and increasing energy needs has focused attention on developing existing unconventional fossil fuels like oil shale and renewable resources such as biomass. Sustainable, renewable and reliable resources of domestically produced biomass comparing to wind and solar energy is a sensible motivation to establish a small-scale power plant using biomass as feed to supply electricity demand and heat for rural development. The work in Paper I focuses on the …

Synthesis And Functionalization Of A Triaryldiamine-Base Photoconductive/Photorefractive Composite, And Its Application To Aberrated Image Restoration, Yichen Liang

Doctoral Dissertations

"Organic photorefractive (PR) composites have recently emerged as an important class of materials for applications including high-density data storage, optical communication, and biomedical imaging. In an effort to further improve their performance, this study focused on the utilization of functionalized semiconductor nanocrystals to photosensitize triaryamine (TPD)-based PR composites, as well as the application of TPD-based PR composites in the restoration of aberrated optical information. A novel approach to functionalize CdSe quantum dot (QCdSe) was firstly introduced where the sulfonated triarydiamine (STPD) was used as charge-transporting ligand to passivate QCdSe. TPD-based photoconductive and PR composites were photosensitized with the STPD-passivated QCdSe …

Wetting Kinetics In Forced Spreading, Amer Mohammad Al-Shareef

Doctoral Dissertations

"Under dynamic conditions, the dynamic contact angle (the angle that the liquid makes with the solid) of a liquid on a solid surface varies dramatically with substrate velocity from its equilibrium value. Experimental data of the dynamic contact angles for polydimethylsiloxane (PDMS or silicone oil) under air on a glass substrate coated with teflon, for water under PDMS, for solutions of the polymer polyethylene oxide (PEO) under air, for solutions of PEO under PDMS, were obtained to simulate and understand the systems of brine or brine containing a polymer displacing viscous crude. A variety of solid substrates were used other …

Cable Analysis For Electromagnetic Compatibility Issues, Guanghua Li

Doctoral Dissertations

"This dissertation consists of three papers. In the first paper, a high-sensitivity resonant electric field probe was designed, consisting of an LC resonator loaded by quarter-wave transformers. At the resonant frequency of 1.577 GHz, the measured |S₂₁| from a matched trace to the resonant probe was approximately 6.6 dB higher than that of an equivalently sized broadband probe.

In the second paper, a method for creating a simple SPICE model is proposed such that the SPICE model allows prediction of radiated emissions in component level tests. The radiation from the ground connections between the cables and return plane …

Small Sample Confidence Bands For The Survival Functions Under Proportional Hazards Model, Emad Mohamed Abdurasul

Doctoral Dissertations

"In this work, a saddlepoint-based method is developed for generating small sample confidence bands for the population survival function from the Kaplan-Meier (KM), the product limit (PL), and Abdushukurov-Cheng-Lin (ACL) survival function estimators, under the proportional hazards model. In the process the exact distribution of these estimators is derived and developed mid-population tolerance bands for said estimators. The proposed saddlepoint method depends upon the Mellin transform of the zero-truncated survival estimator which is derived for the KM, PL, and ACL estimators. These transforms are inverted via saddlepoint approximations to yield highly accurate approximations to the cumulative distribution functions of the …

The Role Of Pre-Existing Basement Fabrics In The Initiation Of Continental Rifting: The Okavango Rift Zone, Botswana, Angelica Alvarez Naranjo

Doctoral Dissertations

"Integrated geophysical, remote sensing, and field investigations of the Okavango Rift Zone (ORZ), Botswana indicate that a feedback between optimum-oriented basement structures and fluid flow influence the nucleation and growth of continental rifts in their incipient stages. The ORZ, the youngest rift of the East African Rift System, occurs within a Proterozoic inter-cratonic suture zone - the NE-trending Precambrian Damara/Ghanzi-Chobe orogenic belts. The Pleistocene to Holocene ORZ forms a ~450 km long and ~100 km wide half-graben bounded by NE-trending normal faults. Basement units within the Damara/Ghanzi-Chobe orogenic belts exhibit a well-developed NE-trending linear fabric (045-065) defined by parallel limbs …