Digital Commons Network^™

Finite Element Modeling Of Patient-Specific Total Shoulder Arthroplasty, Ignacio Rivero Crespo

Electronic Theses and Dissertations

Total Shoulder Arthroplasty (TSA) is a surgical procedure designed to improve joint functionality by replacing the articulation between the humeral head and the glenoid fossa. Anatomic Total Shoulder Arthroplasty (aTSA) and Reverse Total Shoulder Arthroplasty (rTSA) are two types of replacement surgery to relieve pain and restore function of the shoulder. The overall goal of this study was to evaluate the effects of variation of certain patient and implant alignment parameters that may influence long-term outcomes of these surgical procedures, including kinematics, joint loads and contact mechanics. Computational models of six TSA subjects, three aTSA and three rTSA, were created …

The Influence Of Heat And Mass Transfer On The Setting Rate Of Adhesives Between Porous Substrates, Mubarak Mohammed Khlewee

Electronic Theses and Dissertations

The dynamic penetration of fluid into a porous media where other changes are occurring such as temperature or concentration is of interest to a number of situations. However, little experimental and theoretical analysis of this situation is found in the literature where most of the previously published works have studied the penetration with constant physical properties, where there is no change of the fluid as it enters the pores. This situation is important in the setting of adhesives in porous medium such as in the setting of hot melt and water-based adhesives in the production of paper based packaging. The …

Modeling, Simulation And Control Of Microrobots For The Microfactory., Zhong Yang

Electronic Theses and Dissertations

Future assembly technologies will involve higher levels of automation in order to satisfy increased microscale or nanoscale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to the microelectronics and MEMS industries, but less so in nanotechnology. With the boom of nanotechnology since the 1990s, newly designed products with new materials, coatings, and nanoparticles are gradually entering everyone’s lives, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than top-down robotic assembly. This is due to considerations of volume handling of large …

Quantifying The Impacts Of Land Use, Management And Climate Change On Water Resources In Missouri River Basin, Arun Bawa

Electronic Theses and Dissertations

A location-specific evaluation of hydrological landscape responses concerning past and projected climate and land use land cover (LULC) changes can provide a powerful intellectual basis for developing efficient and profitable agroecosystems, and overcoming uncertain and detrimental consequences of LULC and climate shifts. This dissertation assessed the impacts of land use, management, and climate change on water resources in the Missouri River Basin (MRB) through four specific studies that included: (i) to study the responses of leached nutrient concentrations and soil health to winter rye cover crop (CC) under no-till corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation, (ii) to …

Synergistic Environmental Aging Of Glass Reinforced Polymer Composites, Tianyi Lu

Electronic Theses and Dissertations

Synergistic effects involved in the environmental degradation of Glass Reinforced Polymer (GRP) composites were examined and a novel synergistic aging model was proposed in this study. Six GRPs based on glass fibers with four different polymer resins and six pure polymer thermoplastic resins were exposed either individually or in combination to ultraviolet (UV) radiation, water condensation and elevated temperature for approximately 1000 h. The composites and polymers were monitored for weight changes as a function of time and their surfaces were examined after the tests using optical and scanning electron microscopes (SEM). Photodegradation of the polymer matrices was analyzed by …

Computational Modeling And Simulations Of Condition Deterioration To Enhance Asphalt Highway Pavement Design And Asset Management, Zul Fahmi Bin Mohamed Jaafar

Electronic Theses and Dissertations

A nation’s economy and prosperity depend on an efficient and safe transportation network for public mobility and freight transportation. A country’s road network is recognized as one of the largest public infrastructure assets. About 93 percent of 2.6 million miles of paved roads and highways in the United States (U.S.) are surfaced with asphalt. Longitudinal roughness, pavement cracking, potholes, and rutting are the major reasons for rehabilitation of asphalt roads. Billions of dollars are required annually for the maintenance and rehabilitation of road networks. If timely maintenance and rehabilitation are not performed, the pavement damages inflicted by heavy traffic repetitions …

Modeling And Simulation Of The Thermoforming Process In Thermoplastic-Matrix Composite Materials, Philip M. Bean

Electronic Theses and Dissertations

Thermoplastic-matrix composite materials have unique advantages over traditional thermosets including faster processing, improved fracture toughness, and recyclability. These and other benefits have caused increasing interest in the use of these materials in both aerospace and automotive industries. Due to the differences in behavior, these materials require a different type of manufacturing process to thermoset matrix composites. This manufacturing process generally involves using pre manufactured tape-layers. These layers, containing both thermoplastic-matrix and fiber-reinforcement, are aligned to the desired orientation, and stacked up into a “tailored blank” using an automated tape layup machine. They are then heated to the thermoplastic melting temperature …

Effect Of Poisson’S Ratio On Young's Modulus Characterization Using Ultrasonic Technique By Modeling, Michael Onyetube

Electronic Theses and Dissertations

The past 27 years has witnessed a revolutionary growth in the progress of material development and application in almost all industry and business sectors, and this seems to be continuing even today. So many material-driven innovations have enabled the global spread in technology and improvements in capability, ranging from communications to aerospace and healthcare, to automotive and agriculture. Mechanical behavior of elastic materials is modeled by two main independent constants; Young’s modulus and Poisson’s ratio. An accurate measurement of both constants is necessary in most engineering applications, for example, the standard materials used for the calibration of some equipment, quality …

A Framework For Assessing Water Quality, Prioritizing Recovery Potential, And Analyzing Placement Of Best Management Practices, Tadesse Animaw Sinshaw

Electronic Theses and Dissertations

Motivated by the U.S. EPA goals, this research developed a framework to support identification and restoration of nutrient-impaired water bodies. The study objectives were developing total nitrogen (TN) and total phosphorus (TP) prediction models, evaluating the impact of social indicators on assessing recovery potential, and developing a spatial decision support system for choice and placement of best management practices (BMPS). An artificial neural network was used to develop TN and TP predictive regional models for U.S. lakes using easily measurable and cost-effective variables. The performance of models was superior for regions trained with larger datasets and/or regions with lower temperature …

System Identification Of A Circulation Control Unmanned Aerial Vehicle, Mohammed Agha

Electronic Theses and Dissertations

The advancement in automation and sensory systems in recent years has led to an increase the demand of UAV missions. Due to this increase in demand, the research community has gained interest in investigating UAV performance enhancing systems. Circulation Control (CC), which is an active control flow method used to enhance UAV lift, is a performance enhancing system currently studied. In prior research, experimental studies have shown that Circulation Control wings (CCW) implemented on class-I UAVs can reduce take-off distance by 54%. Wind tunnel tests reveal that CC improves aircraft payload capabilities through lift enhancement. Increasing aircraft payload capabilities causes …

Statistical Shape Modeling To Quantify Variation In The Proximal Humeral Anatomy, Paul B. Sade Sr.

Electronic Theses and Dissertations

The fit of the humeral prosthesis to the intramedullary canal and the replication of the anatomic humeral head center are important factors in Total Shoulder Arthroplasty (TSA). The objective of this thesis was to develop a Statistical Shape Model (SSM) of the cortical and cancellous bone regions of the proximal humerus, and to assess potential shape differences with gender and ethnicity, with a goal of informing implant design. An SSM was used and Principal Component Analysis (PCA) was applied to data that represented both the cancellous and cortical humeral bone of 63 healthy subjects and cadavers. Anatomical measurements and PC …

Specimen-Specific Natural, Pathological, And Implanted Knee Mechanics Using Finite Element Modeling, Azhar Akber Ali

Electronic Theses and Dissertations

There is an increasing incidence of knee pain and injury among the population, and increasing demand for higher knee function in total knee replacement designs. As a result, clinicians and implant manufacturers are interested in improving patient outcomes, and evaluation of knee mechanics is essential for better diagnosis and repair of knee pathologies. Common knee pathologies include osteoarthritis (degradation of the articulating surfaces), patellofemoral pain, and cruciate ligament injury and/or rupture. The complex behavior of knee motion presents unique challenges in the diagnosis of knee pathology and restoration of healthy knee function. Quantifying knee mechanics is essential for developing successful …

Computation Aided Design Of Multicomponent Refractory Alloys With A Focus On Mechanical Properties, Paul Daniel Clark

Electronic Theses and Dissertations

Quantum mechanical calculations paired with exponential growth in computer processing speed has created a paradigm shift in materials discovery. Simulations can be carried out to accurately predict structure-composition-property relationships of novel systems. This work focuses on calculating elastic properties of high entropy alloys, a new class of alloys that are built from 4+ elements in equi-atomic proportion. These alloys often exhibit simple microstructures and each constituent element contributes its properties to the overall bulk properties of the amalgamated material. This "cocktail" effect has led to the discovery of many alloys which could drive technical advances in the future. Elastic properties …

Multiscale Musculoskeletal Modeling Of The Lower Limb To Perform Personalized Simulations Of Movement, Alessandro Navacchia

Electronic Theses and Dissertations

Computational modeling has been used for many decades to inform design and decision-making in several fields of engineering, such as aerospace, automotive, petroleum, and others. However, it still struggles to have a similar impact in fields of medicine, such as orthopaedics. Three of the challenges that have limited the use of computational modeling in the clinical practice and in product development are model validation, personalization, and realism. Validation is a challenge because several internal parameters of the human body, such as muscle forces, are not safely measurable in vivo and, consequently, a thorough comparison between model outputs …

Information Propagation Algorithms For Consensus Formation In Decentralized Multi-Agent Systems, Christopher Hollander

Electronic Theses and Dissertations

Consensus occurs within a multi-agent system when every agent is in agreement about the value of some particular state. For example, the color of an LED, the position or magnitude of a vector, a rendezvous location, the most recent state of data within a database, or the identity of a leader are all states that agents might need to agree on in order to execute their tasking. The task of the decentralized consensus problem for multi-agent systems is to design an algorithm that enables agents to communicate and exchange information such that, in finite time, agents are able to form …

Assessing Biofiltration Pretreatment For Ultrafiltration Membrane Processes, Andrea Cumming

Electronic Theses and Dissertations

An engineered biological filtration (biofiltration) process treating a nutrient-enriched, low-alkalinity, organic-laden surface water downstream of conventional coagulation-clarification and upstream of an ultrafiltration (UF) membrane process was assessed for its treatment effectiveness. The impact of biofiltration pretreatment on UF membrane performance was evaluated holistically by investigating the native source water chemistry and extending the analysis into the drinking water distribution system. The biofiltration process was also compared in treatment performance to two alternative pretreatment technologies, including magnetic ion exchange (MIEX®) and granular activated carbon (GAC) adsorption. The MIEX®, GAC adsorption, and biologically active carbon (BAC) filtration pretreatments were integrated with conventional …

A Generic Framework For Multi-Method Modeling And Simulation Of Complex Systems Using Discrete Event, System Dynamics And Agent Based Approaches., Konstantinos Mykoniatis

Electronic Theses and Dissertations

Decisions about Modeling and Simulation (M&S) of Complex Systems (CS) need to be evaluated prior to implementation. Discrete Event (DE), System Dynamics (SD), and Agent Based (AB) are three different M&S approaches widely applied to enhance decision-making of complex systems. However, single type M&S approaches can face serious challenges in representing the overall multidimensional nature of CS and may result in the design of oversimplified models excluding important factors. Conceptual frameworks are necessary to offer useful guidance for combining and/or integrating different M&S approaches. Although several hybrid M&S frameworks have been described and are currently deployed, there is limited guidance …

Stress Corrosion Cracking In Polymer Matrix Glass Fiber Composites, Jonathan Kosak

Electronic Theses and Dissertations

With the use of Polymer Matrix Glass Fiber Composites ever expanding, understanding conditions that lead to failure before expected service life is of increasing importance. Stress Corrosion Cracking (SCC) has proven to be one such example of conditions found in use in high voltage transmission line applications that leads to brittle fracture of polymer matrix composites.

SCC has been proven to be the result of acid buildup on the lines due to corona discharges and water buildup. This acid leaches minerals from the fibers, leading to fracture at low loads and service life. In order to combat this problem, efforts …

Design And Development Of Heterogenous Combustion Systems For Lean Burn Applications, Anthony Terracciano

Electronic Theses and Dissertations

Combustion with a high surface area continuous solid immersed within the flame, referred to as combustion in porous media, is an innovative approach to combustion as the solid within the flame acts as an internal regenerator distributing heat from the combustion byproducts to the upstream reactants. By including the solid structure, radiative energy extraction becomes viable, while the solid enables a vast extension of flammability limits compared to conventional flames, while offering dramatically reduced emissions of NOx and CO, and dramatically increased burning velocities. Efforts documented within are used for the development of a streamlined set of design principles, and …

Modeling And Fault Detection In Dc Side Of Photovoltaic Arrays, Mohd Akram

Electronic Theses and Dissertations

Fault detection in PV systems is a key factor in maintaining the integrity of any PV system. Faults in photovoltaic systems can cause irrevocable damages to the stability of the PV system and substantially decrease the power output generated from the array of PV modules. Among'st the various AC and DC faults in a PV system, the clearance of the AC side faults is achieved by conventional AC protection schemes,the DC side, however , there still exists certain faults which are difficult to detect and clear. This paper deals with the modeling, detection and classification of these types of DC …

Understanding The Capabilities And Limitations Of Advanced Interactive M&S: A Cricothyroidotomy Simulation Case Study, Lillian Campbell-Wynn

Electronic Theses and Dissertations

Simulation for surgical education and training is increasingly perceived as a valuable contribution to traditional teaching methods providing a structured learning experience. Surgical simulations allow surgeons to practice tactics, techniques and procedures numerous times without the cost, limitations and ethical problems of using cadaver-based models. The goal of this research is to advance the use of modeling and simulation in support of emergency medical training. This research explores questions identified through a case study of two different modeling and simulation techniques – virtual reality and mannequins - in the support of combat emergency medical education and training. To reduce the …

Modeling And Simulation Of All-Electric Aircraft Power Generation And Actuation, David Woodburn

Electronic Theses and Dissertations

Modern aircraft, military and commercial, rely extensively on hydraulic systems. However, there is great interest in the avionics community to replace hydraulic systems with electric systems. There are physical challenges to replacing hydraulic actuators with electromechanical actuators (EMAs), especially for flight control surface actuation. These include dynamic heat generation and power management. Simulation is seen as a powerful tool in making the transition to all-electric aircraft by predicting the dynamic heat generated and the power flow in the EMA. Chapter 2 of this dissertation describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. …

Exploration Of The Impact Of Affective Variables On Human Performance In A Live Simulation, Ken Westerlund

Electronic Theses and Dissertations

Live simulations play an important role in allowing users to practice and develop skills they learn in training. Although live simulations are playing an increasingly important role in training, ways to improve them are not well understood or documented. In order to improve the efficacy of live simulation and maximize results from funds spent on training; this research examines the relationship between the affective variables of the participants and their performance in the live simulation. Prior to participating in the instructor development live simulation used in this study two training preference scales were administered to a group of trainees. These …

Towards A Fluid Solid Interaction Model Of A Dynamic Lung, Justin C. Jacobs

Electronic Theses and Dissertations

Because the pulmonary system is a site for both environmental particulate contamination, as well as drug delivery into the body, numerous research groups have focused on precisely understanding its inner-workings. Past research has demonstrated the need to realistically model the lung walls in order to accurately capture the complex airflow profile throughout all of the branches. Since this is paramount to properly replicating particulate transport in the lung, computational fluid dynamics simulations on their own are inadequate, as they cannot account for lung wall dilation. Only by coupling the fluid and solid domains can natural lung behavior can be effectively …

Surface Measurements And Predictions Of Full-Coverage Film Cooling, Gregory Natsui

Electronic Theses and Dissertations

Full-coverage film cooling is investigated both experimentally and numerically. First, surface measurements local of adiabatic film cooling effectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-ε and SST k-ω, and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of …

Finite Element Modeling Of Seismic Wave Propagation In Earthen Embankments, Binyam Tadese

Electronic Theses and Dissertations

The detection of internal seepage zones in embankments (dams and levees) by geophysical seismic techniques such as seismic refraction is limited by a number of factors. Some factors are associated with inversion and smoothing problems during processing, while others are associated with the natural characteristics of embankments and seepage anomalies. In this research, changes in the seismic response associated with: embankment soil compositions and moisture, characteristics of the seepage zone, presence of water in the reservoir, and shape of embankment was studied via 2D and 3D finite element (FE) embankment models. Artificial reflections from external boundaries and numerical dispersion were …

Unified Large And Small Signal State-Space Based Modeling And Symbolic Simulation For Pwm Converters, Ehab Shoubaki

Electronic Theses and Dissertations

In this Dissertation, which concentrates on discrete modeling for control purposes of DC/DC converters and simulation through symbolic techniques. A Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulation of the converter switches, and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulation, this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic …

Modeling Of Liquid Crystal Display And Photonic Devices, Zhibing Ge

Electronic Theses and Dissertations

Liquid crystal (LC) materials have been widely applied in electro-optical devices, among which display is the most successful playground and numerous new applications in photonic areas (such as laser beam steering devices) are also emerging. To well guide the device design for optimum performance, accurate modeling is of prior and practical importance. Generally, the modeling of LC devices includes two parts in sequence: accurate LC molecule deformation extraction under external electric fields and optical calculation thereafter for the corresponding electro-optical behaviors. In this dissertation, first, hybrid finite element method and finite difference method are developed to minimize the free energy …

An Investigation Of Size Exclusion And Diffusion Controlled Membrane Fouling, Colin Michael Hobbs

Electronic Theses and Dissertations

The reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased chemical cleaning frequencies, and increased membrane replacement frequencies. The most significant practical implication of membrane fouling is increased operating and maintenance costs. As such, membrane fouling must be properly managed to …

Four Terminal Junction Field-Effect Transistor Model For Computer-Aided Design, Hao Ding

Electronic Theses and Dissertations

A compact model for four-terminal (independent top and bottom gates) junction field-effect transistor (JFET) is presented in this dissertation. The model describes the steady-state characteristics with a unified equation for all bias conditions that provides a high degree of accuracy and continuity of conductance, which are important for predictive analog circuit simulations. It also includes capacitance and leakage equations. A special capacitance drop-off phenomenon at the pinch-off region is studies and modeled. The operations of the junction fieldeffect transistor (JFET) with an oxide top-gate and full oxide isolation are analyzed, and a semi-physical compact model is developed. The effects of …