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Full-Text Articles in Engineering
Application Of High-Deflection Strain Gauges To Characterize Spinal-Motion Phenotypes Among Patients With Clbp, Spencer Alan Baker
Application Of High-Deflection Strain Gauges To Characterize Spinal-Motion Phenotypes Among Patients With Clbp, Spencer Alan Baker
Theses and Dissertations
Chronic low back pain (CLBP) is a nonspecific and persistent ailment that entails many physiological, psychological, social, and economic consequences for individuals and societies. Although there is a plethora of treatments available to treat CLBP, each treatment has varying efficacy for different patients, and it is currently unknown how to best link patients to their ideal treatment. However, it is known that biopsychosocial influences associated with CLBP affect the way that we move. It has been hypothesized that identifying phenotypes of spinal motion could facilitate an objective and repeatable method of determining the optimal treatment for each patient. The objective …
Time-Dependent Strain-Resistance Relationships In Silicone Nanocomposite Sensors, Alex Mikal Wonnacott
Time-Dependent Strain-Resistance Relationships In Silicone Nanocomposite Sensors, Alex Mikal Wonnacott
Theses and Dissertations
Flexible high-deflection strain gauges have been demonstrated as cost-effective and accessible sensors for capturing human biomechanical deformations. However, the interpretation of these sensors is notably more complex compared to conventional strain gauges, partially owing to the viscoelastic nature of the strain gauges. On top of the non-linear viscoelastic behavior, dynamic resistance response is even more difficult to capture due to spikes in resistance during strain changes. This research examines the relationships between stress, strain, and resistance in nanocomposite sensors during dynamic strain situations. Under the assumption that both macroscopic stress and resistance are governed by microscopic stress concentrations at the …
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Theses and Dissertations
This work evaluates the relative significance of forces determining the motion of a pulverized coal particle under conditions representative of a pressurized oxy-coal combustor. The gravity force and surface forces of drag, fluid stress, added mass, and Basset history are discussed and appropriate forms of these force equations are chosen, with a consideration of spherical and non-spherical drag and the Basset history kernel. Studies from the literature that emphasize specific forces are used to validate the implementation of the force equations and correlations. Modeling is based on time-averaged, one-dimensional motion of a single non-reacting particle along the centerline of a …
Parametric Models Of Maize Stalk Morphology, Michael Alan Ottesen
Parametric Models Of Maize Stalk Morphology, Michael Alan Ottesen
Theses and Dissertations
As the most produced grain crop world-wide, 5% of corn is lost due to stalk lodging (above-ground structural failure of the stalk near the roots). Current modeling methods lack the ability to manipulate the stalk architecture. In contrast, parameterized models enable advanced analyses such as sensitivity and optimization studies. This thesis advances previous work on a parameterized cross-sectional model of maize stalk morphology and investigates the validity of a parameterized three-dimensional model. The parameterized cross-sectional model is based upon previous work that approximated the cross-section of maize stalks using an ellipse plus principal components. Validation of the cross-sectional model was …
Modeling The Effects Of Parameter Changes On Heating And Pressure At The Weld Interface And Joint Strength In Friction Bit Joining, Adam Hartly Wagner
Modeling The Effects Of Parameter Changes On Heating And Pressure At The Weld Interface And Joint Strength In Friction Bit Joining, Adam Hartly Wagner
Theses and Dissertations
Joining of dissimilar metals is a process that is of interest in many fields, especially the automotive industry where lightweighting of the body structure is important. However, creating strong joints between dissimilar metals can be challenging. Friction bit joining (FBJ) is a solid-state method that uses a consumable bit to create a strong joint between dissimilar metals such as aluminum and steel. The purpose of this research is to gain understanding of how adjusting FBJ parameters affects the heating and pressure at the weld interface using a modeling approach, in order to better understand the bonding process. The questions guiding …
Coal Pyrolysis Models For Use In Massively Parallel Oxyfuel-Fired Boiler Simulations, Andrew Perry Richards
Coal Pyrolysis Models For Use In Massively Parallel Oxyfuel-Fired Boiler Simulations, Andrew Perry Richards
Theses and Dissertations
Accurately modeling key aspects of coal combustion allows for the virtual testing and application of new technologies and processes without the need for investments in lab- and pilot-scale facilities, since such facilities may only be used for a few small tests. However, modeling of subprocesses must not only be accurate but computationally efficient. Modeling of coal devolatilization reactions and processes are one of the important parts of large-scale simulations of coal combustion systems. The work presented here details efforts to improve the modeling of coal devolatilization processes in massively-parallel simulations of coal combustors, including: (1) devolatilization rate/yield models, (2) modeling …
Characterization And Optimization Of An Image Charge Detector For The Measurement Of Martian Dust, Jace Rozsa
Characterization And Optimization Of An Image Charge Detector For The Measurement Of Martian Dust, Jace Rozsa
Theses and Dissertations
Image charge detector (ICD) technology has existed for decades. However, not until recently has an ICD been proposed for use in space exploration, specifically for studying the characteristics of the dust on Mars. Characterizing the dust on Mars is crucial for designing equipment to aid manned missions. It also improves our understanding of Mars' climate and weather systems. An ICD utilizing printed circuit board (PCB) electrodes, coupled with a custom differential amplifier, is best suited for this type of measurement because of its light weight, simplicity, and noise performance. The noise floor of our particular amplifier is measured to be …
Modeling The Influence Of Changes In Aliphatic Structure On Char Surface Area During Coal Pyrolysis, He Yang, Thomas H. Fletcher, Yang Li, Lijun Jin, Sufen Li, Yan Shang, Haoquan Hu
Modeling The Influence Of Changes In Aliphatic Structure On Char Surface Area During Coal Pyrolysis, He Yang, Thomas H. Fletcher, Yang Li, Lijun Jin, Sufen Li, Yan Shang, Haoquan Hu
Faculty Publications
The influence of changes in aliphatic structure on char surface area during coal pyrolysis was modeled, and the effect was introduced to a previous char surface area model for lignite pyrolysis established based on the chemical percolation devolatilization (CPD) model. The modified model can predict not only the N2 and CO2 char surface area during rapid pyrolysis of three lignites but also the CO2 char surface area of two high-volatile bituminous coals; the agreement of the modified model with experiments is improved at high temperatures. The decrease in aliphatic chain length can reduce adsorption positions around aromatic core, and decrease …
Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston
Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston
Theses and Dissertations
Finite element models of friction welding can be used to estimate internal conditions of welds which are useful for weld analysis and developing experimental welding procedures. Many modeling techniques are used to accomplish these goals, each with relative strengths and weaknesses. A comparative analysis of friction welding models using different heat generation methods is presented. The three different heat generation methods examined were viscoplastic friction, constant steady-state generation, and experimentally measured power data. The models were compared against each other using three output measurements: temperature, axial force, and upset. The friction model predicted temperatures within 40 degrees C. Temperature accuracy …
Smart Technologies For Oil Production With Rod Pumping, Brigham Wheeler Hansen
Smart Technologies For Oil Production With Rod Pumping, Brigham Wheeler Hansen
Theses and Dissertations
This work enables accelerated fluid recovery in oil and gas reservoirs by automatically controlling fluid height and bottomhole pressure in wells. Several literature studies show significant increase in recovered oil by determining a target bottomhole pressure but rarely consider how to control to that value. This work enables those benefits by maintaining bottomhole pressure or fluid height. Moving Horizon Estimation (MHE) determines uncertain well parameters using only common surface measurements. A Model Predictive Controller (MPC) adjusts the stroking speed of a sucker rod pump to maintain fluid height. Pump boundary conditions are simulated with Mathematical Programs with Complementarity Constraints (MPCCs) …
An Overview Of Current Applications, Challenges, And Future Trends In Distributed Process-Based Models In Hydrology, Simone Fatichi, Enrique R. Vivoni, Fred L. Ogden, Valeriy Y. Ivanov, Benjamin Mirus, David Gochis, Charles W. Downer, Matteo Camporese, Jason H. Davidson, Brian Ebel, Norm Jones, Jongho Kim, Giuseppe Mascaro, Richard Niswonger, Pedro Restrepo, Riccardo Rigon, Chaopeng Shen, Mauro Sulis, David Tarboton
An Overview Of Current Applications, Challenges, And Future Trends In Distributed Process-Based Models In Hydrology, Simone Fatichi, Enrique R. Vivoni, Fred L. Ogden, Valeriy Y. Ivanov, Benjamin Mirus, David Gochis, Charles W. Downer, Matteo Camporese, Jason H. Davidson, Brian Ebel, Norm Jones, Jongho Kim, Giuseppe Mascaro, Richard Niswonger, Pedro Restrepo, Riccardo Rigon, Chaopeng Shen, Mauro Sulis, David Tarboton
Faculty Publications
Process-based hydrological models have a long history dating back to the 1960s. Criticized by some as over-parameterized, overly complex, and difficult to use, a more nuanced view is that these tools are necessary in many situations and, in a certain class of problems, they are the most appropriate type of hydrological model. This is especially the case in situations where knowledge of flow paths or distributed state variables and/or preservation of physical constraints is important. Examples of this include: spatiotemporal variability of soil moisture, groundwater flow and runoff generation, sediment and contaminant transport, or when feedbacks among various Earth’s system …
Simple Models For Estimating The Rotational Stiffness Of Steel Column-To-Footing Connections, Joshua Edwin Tryon
Simple Models For Estimating The Rotational Stiffness Of Steel Column-To-Footing Connections, Joshua Edwin Tryon
Theses and Dissertations
Despite the crucial role they play in transferring loads from the superstructure to the foundation, steel column-to-footing connections have received little attention in research. Though shallow embedded connections are typically characterized as pinned, studies have shown that they exhibit significant rotational stiffness. The objective of this thesis is to quantify the rotational stiffness of such connections. A method named the continuum model is developed by which the rotational stiffness of embedded connections may be calculated. Outputs from this model are compared with experimental data on steel connections embedded in concrete. The continuum model is shown to be capable of reasonably …
A Cloud-Based Gssha Index Map Editor Utility For Watershed Decision Support, Jocelynn Marie Anderson
A Cloud-Based Gssha Index Map Editor Utility For Watershed Decision Support, Jocelynn Marie Anderson
Theses and Dissertations
Preventing damages from flooding is critically important for city managers and planners.Efforts in protecting infrastructure from flooding are often coupled with building hydrologicmodels to provide predictions of what is likely to happen during storm events. As land usechanges, these models must be updated, which is more challenging with sophisticated models. Ateam of researchers from universities in Utah and Wyoming have been developing tools forwater management in the Intermountain West as part of a collaborative NSF research grantcalled CI-WATER. In particular, a free and open source web platform called Tethys has beendeveloped to support the development and hosting of hydrologic web …
Tethys Platform: A Development And Hosting Platform For Water Resources Web Apps, Nathan R. Swain
Tethys Platform: A Development And Hosting Platform For Water Resources Web Apps, Nathan R. Swain
Theses and Dissertations
The interactive nature of web applications or “web apps” makes it an excellent medium for conveying complex scientific concepts to lay audiences and creating decision support tools that harness cutting edge modeling techniques. However, the technical expertise required to develop them represents a barrier for would-be developers. The barrier can be characterized by the following hurdles that developers must overcome: (1) identify, select, and install software that meet the spatial and computational capabilities commonly required for water resources modeling; (2) orchestrate the use of multiple FOSS and FOSS4G projects and navigate their differing application programming interfaces (APIs); (3) learn the …
Measurement And Modeling Of Fire Behavior In Leaves And Sparse Shrubs, Dallan R. Prince
Measurement And Modeling Of Fire Behavior In Leaves And Sparse Shrubs, Dallan R. Prince
Theses and Dissertations
Wildland fuels and fire behavior have been the focus of numerous studies and models which provide operational support to firefighters. However, fuel and fire complexity in live shrubs has resulted in unexpected and sometimes aggressive fire behavior. The combustion of live fuels was studied and modeled, and the results were assimilated into a shrub-scale fire behavior model which assumes fire spread by flame-fuel overlap. Fire spread models have usually assumed that radiation heat transfer is responsible for driving fire spread, but that assumption is a topic of continuing debate, and appears to contradict some experimental observations. A convection-based shrub-scale fire …
Modeling-As-A-Service (Maas) Using The Cloud Services Innovation Platform (Csip), Olaf David, Wes Lloyd, Ken Rojas, Mazdak Arabi, Frank Geter, James Ascough, Tim Green, G. Leavesley, Jack Carlson
Modeling-As-A-Service (Maas) Using The Cloud Services Innovation Platform (Csip), Olaf David, Wes Lloyd, Ken Rojas, Mazdak Arabi, Frank Geter, James Ascough, Tim Green, G. Leavesley, Jack Carlson
International Congress on Environmental Modelling and Software
Cloud infrastructures for modelling activities such as data processing, performing environmental simulations, or conducting model calibrations/optimizations provide a cost effective alternative to traditional high performance computing approaches. Cloud-based modelling examples emerged into the more formal notion: "Model-as-a-Service" (MaaS). This paper presents the Cloud Services Innovation Platform (CSIP) as a software framework offering MaaS. It describes both the internal CSIP infrastructure and software architecture that manages cloud resources for typical modelling tasks, and the use of CSIP's "ModelServices API" for a modelling application. CSIP's architecture supports fast and resource aware auto-scaling of computational resources. An example model service is presented: the …
Interactive Web-Based Flood Modeling At Country Wide Scale And Plantar Size Resolution, Fedor Baart, Jack Ha, Arthur Van Dam, Gennadii Donchyts, Martijn Siemerink
Interactive Web-Based Flood Modeling At Country Wide Scale And Plantar Size Resolution, Fedor Baart, Jack Ha, Arthur Van Dam, Gennadii Donchyts, Martijn Siemerink
International Congress on Environmental Modelling and Software
The flooding of rural and urban areas is an increasing hazard to society. Accurate and timely predictions are essential for the water manager to prepare and respond to these hazards. Predicting flooding requires a numerical model that represents the physical processes (rain, evaporation, infiltration, overland flow, groundwater flow). This model, fed with measurements, and possible measures, calculates the expected flooding. The traditional working method consists of a three step process: schematization setup, running and post-processing, with a total feedback time of hours. This process is suitable for confirmatory modeling. Most of the time, models are applied exploratory, requiring a different …
Application Of One Dimensional Turbulence (Odt) To Model Fire Spread Through Biomass Fuel Bed, Abinash Paudel
Application Of One Dimensional Turbulence (Odt) To Model Fire Spread Through Biomass Fuel Bed, Abinash Paudel
Theses and Dissertations
Each year fires destroy millions of acres of woodland, lives, and property, and significantly contribute to air pollution. Increased knowledge of the physics and properties of the flame propagation is necessary to broaden the fundamental understanding and modeling capabilities of fires. Modeling flame propagation in fires is challenging because of the various modes of heat transfer with diverse fuels, multi-scale turbulence, and complex chemical kinetics. Standard physical models of turbulence like RANS and LES have been used to understand the flame behavior, but these models are limited by computational cost and their inability to resolve sub-grid scales. Application of several …
Model Development And Application Of Molecular Simulations For The Study Of Proton Transport In Bulk Water And For The Prediction Of Dipole Moments Of Organic Compounds, Abhishek Asthana
Theses and Dissertations
The present work demonstrates the application of molecular simulations (MD) in two different areas: proton transport in bulk water and estimation of the dipole moment of polar organic compounds. In both areas, relatively few successful and robust methodologies exist. In the first part, a new polarizable water model is developed for MD simulations of the proton transport process. The model was parametrized from a combination of quantum chemical calculations and experimental water properties. The model was implemented in MD simulation studies of liquid water at room temperature, as well as with excess protons. For pure water the model gave good …
An Evaluation Of Constitutive Laws And Their Ability To Predict Flow Stress Over Large Variations In Temperature, Strain, And Strain Rate Characteristic Of Friction Stir Welding, Katherine Lynn Kuykendall
An Evaluation Of Constitutive Laws And Their Ability To Predict Flow Stress Over Large Variations In Temperature, Strain, And Strain Rate Characteristic Of Friction Stir Welding, Katherine Lynn Kuykendall
Theses and Dissertations
Constitutive laws commonly used to model friction stir welding have been evaluated, both qualitatively and quantitatively, and a new application of a constitutive law which can be extended to materials commonly used in FSW is presented. Existing constitutive laws have been classified as path-dependent or path-independent. Path-independent laws have been further classified according to the physical phenomena they capture: strain hardening, strain rate hardening, and/or thermal softening. Path-dependent laws can track gradients in temperature and strain rate characteristic to friction stir welding; however, path-independent laws cannot. None of the path-independent constitutive laws evaluated has been validated over the full range …
Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel
Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel
Theses and Dissertations
The ability to effectively adapt a mesh is a very important feature of high fidelity finite element modeling. In a finite element analysis, a relatively high node density is desired in areas of the model where there are high error estimates from an initial analysis. Providing a higher node density in such areas improves the accuracy of the model and reduces the computational time compared to having a high node density over the entire model. Node densities can be determined for any model using the sizing functions based on the geometry of the model or the error estimates from the …
Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse
Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse
Theses and Dissertations
A numerical model of friction stir welding developed by T. DebRoy, R. Nandan, and others has been optimized to fit experimental data of eleven welds of 304L stainless steel at various weld feed rates and spindle speeds. Optimization was used to determine the values of five difficult-to-measure model parameters. The optimal parameter values were then correlated to the weld machine inputs. The mechanical efficiency and the coefficient of friction were not correlated with feed rate, spindle speed, or axial pressure. Tool slip was positively correlated with feed rate, negatively correlated with spindle speed, and not correlated with axial pressure. The …
Stochastic Spatio-Temporal Uncertainty In Gis-Based Water Quality Modeling Of The Land Water Interface, Ahmad Mohamad Salah
Stochastic Spatio-Temporal Uncertainty In Gis-Based Water Quality Modeling Of The Land Water Interface, Ahmad Mohamad Salah
Theses and Dissertations
Integrated water resources management has been used for decades in various formats. The limited resources and the ever growing population keep imposing pressure on decision makers to better-, and reliably, manage the available waters. On the other hand, the continuous development in computing and modeling power has helped modelers and decision makers considerably. To use these models, assumptions have to be made to fill in the gaps of missing data and to approximate the current conditions. The type and amount of information available can also be used to help select the best model from the currently available models. Advances in …
Assessing Water Quality Modeling In Subtropical Regions Based On A Case Study Of The Aguamilpa Reservoir, Oliver Obregon
Assessing Water Quality Modeling In Subtropical Regions Based On A Case Study Of The Aguamilpa Reservoir, Oliver Obregon
Theses and Dissertations
The shortage of water in Mexico has made public and private institutions look at reservoirs as an alternative solution for present and future water supply. However, eighty percent of the existing reservoirs in Mexico are contaminated at some level, many severely. Water quality models are water-management tools used to diagnose water quality problems and the impact of various environmental conditions. They can be effective in assessing various measures of remediation leading to improved water quality. In most of the cases such water quality models have been successfully applied in reservoirs located in temperate climates. However, the use of water quality …
Multidimensional Modeling Of Solid Propellant Burning Rates And Aluminum Agglomeration And One-Dimensional Modeling Of Rdx/Gap And Ap/Htpb, Matthew Wilder Tanner
Multidimensional Modeling Of Solid Propellant Burning Rates And Aluminum Agglomeration And One-Dimensional Modeling Of Rdx/Gap And Ap/Htpb, Matthew Wilder Tanner
Theses and Dissertations
This document details original numerical studies performed by the author pertaining to solid propellant combustion. Detailed kinetic mechanisms have been utilized to model the combustion of the pseudo-propellants RDX/GAP and AP/HTPB. A particle packing model and a diffusion flame model have been utilized to develop a burning rate and an aluminum agglomeration model. The numerical model for RDX/GAP combustion utilizes a "universal" gas-phase kinetic mechanism previously applied to combustion models of several monopropellants and pseudo-propellants. The kinetic mechanism consists of 83 species and 530 reactions. Numerical results using this mechanism provide excellent agreement with RDX and GAP burning rate data, …
A Mechanistic Investigation Of Nitrogen Evolution In Pulverized Coal Oxy-Fuel Combustion, Andrew John Mackrory
A Mechanistic Investigation Of Nitrogen Evolution In Pulverized Coal Oxy-Fuel Combustion, Andrew John Mackrory
Theses and Dissertations
Oxy-fuel combustion is an enabling technology for capture of CO2 from coal combustion, the economics of which depends strongly on the ability of the process to produce low NOX emissions. The literature contains many reports of lower NOX emissions from oxy-fuel combustion but the reasons for this are not fully understood. The objective of this work was to gain understanding of nitrogen evolution under pulverized coal oxy-fuel conditions. Pulverized coal was burned in a once-through, down-fired, laminar flow reactor. Nitrogen compounds and other combustion species were measured at the reactor centerline as a function of distance from the burner. Dry …
Parametric Optimization Design System For A Fluid Domain Assembly, Matthew Jackson Fisher
Parametric Optimization Design System For A Fluid Domain Assembly, Matthew Jackson Fisher
Theses and Dissertations
Automated solid modeling, integrated with computational fluid dynamics (CFD) and optimization of a 3D jet turbine engine has never been accomplished. This is due mainly to the computational power required, and the lack of associative parametric modeling tools and techniques necessary to adjust and optimize the design. As an example, the fluid domain of a simple household fan with three blades may contain 500,000 elements per blade passage. Therefore, a complete turbine engine that includes many stages, with sets of thirty or more blades each, will have hundreds of millions of elements. The fluid domains associated with each blade creates …
Parallel Processing Of Reactive Transport Models Using Openmp, Jared D. Mclaughlin
Parallel Processing Of Reactive Transport Models Using Openmp, Jared D. Mclaughlin
Theses and Dissertations
Transport codes are beginning to be parallelized in order to allow more complex add-ons, such as geochemical packages, to utilize finer, more accurate grids, and to reduce solution times making stochastic and Monte Carlo simulations more feasible. Most codes parallelized via MPI (message passing interface) offer good results, but require the development of a new parallel code. OpenMP, the shared-memory standard, offers incremental parallelization, allowing sequential codes to remain relatively intact with minimal changes or additions. OpenMP allows speedup to be seen on personal computers with dual processors or greater, unlike some other parallelization approaches that require a supercomputer. An …
A Model For Predicting The Piezoresistive Effect In Microflexures Experiencing Bending And Tension Loads, Gary K. Johns, Larry L. Howell, Brian D. Jensen, Timothy W. Mclain
A Model For Predicting The Piezoresistive Effect In Microflexures Experiencing Bending And Tension Loads, Gary K. Johns, Larry L. Howell, Brian D. Jensen, Timothy W. Mclain
Faculty Publications
This paper proposes a model for predicting the piezoresistive effect in microflexures experiencing bending stresses. Linear models have long existed for describing piezoresistivity for members in pure tension and compression. However, extensions of linear models to more complex loading conditions do not match with experimental results. A second-order model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. A reduced form of the general second-order model is presented for thin flexures in bending. A three-step approach is used to determine the piezoresistive coefficients for this reduced-form model. The approach is demonstrated for two sets of …
One-Dimensional Radial Flow Turbomachinery Performance Modeling, Robert John Pelton
One-Dimensional Radial Flow Turbomachinery Performance Modeling, Robert John Pelton
Theses and Dissertations
The Two-Element In Series (TEIS) and Two-Zone models have been used successfully for over twenty years to model test data for radial flow compressors and pumps. The models can also be used to predict the performance of new machines provided that the model inputs can be accurately specified. Unfortunately, use of the TEIS and Two-Zone models as a predictive tool has been limited because an accurate and broadly applicable method of predicting the modeling parameters, etaA, etaB, chi and d2p does not exist. Empirical models have been developed to predict the TEIS and Two-Zone modeling parameters based on a large …