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Articles 1  12 of 12
FullText Articles in Engineering
General NonlinearMaterial Elasticity In Classical OneDimensional Solid Mechanics, Ronald Joseph Giardina Jr
General NonlinearMaterial Elasticity In Classical OneDimensional Solid Mechanics, Ronald Joseph Giardina Jr
University of New Orleans Theses and Dissertations
We will create a class of generalized ellipses and explore their ability to define a distance on a space and generate continuous, periodic functions. Connections between these continuous, periodic functions and the generalizations of trigonometric functions known in the literature shall be established along with connections between these generalized ellipses and some spectrahedral projections onto the plane, more specifically the wellknown multifocal ellipses. The superellipse, or Lam\'{e} curve, will be a special case of the generalized ellipse. Applications of these generalized ellipses shall be explored with regards to some onedimensional systems of classical mechanics. We will adopt the RambergOsgood ...
MultiTap Extended Kalman Filter For A Periodic Waveform With Uncertain Frequency And Waveform Shape, And Data Dropouts, Justin Saboury
MultiTap Extended Kalman Filter For A Periodic Waveform With Uncertain Frequency And Waveform Shape, And Data Dropouts, Justin Saboury
Theses and Dissertations
Gait analysis presents the challenge of detecting a periodic waveform in the presence of time varying frequency, amplitude, DC offset, and waveform shape, with acquisition gaps from partial occlusions. The combination of all of these components presents a formidable challenge. The Extended Kalman Filter for this system model has six states, which makes it weakly identifiable within the standard Extended Kalman Filter network. In this work, a novel robust Extended Kalman Filterbased approach is presented and evaluated for clinical use in gait analysis. The novel aspect of the proposed method is that at each sample, the present and several past ...
A Monolithic Arbitrary LagrangianEulerian Finite Element Method For An Unsteady Stokes/Parabolic Interface Problem, Ian Kesler
UNLV Theses, Dissertations, Professional Papers, and Capstones
In this thesis, a nonconservative arbitrary LagrangianEulerian (ALE) method is developed
and analyzed for a type of linearized FluidStructure Interaction (FSI) problem in a
time dependent domain with a moving interface  an unsteady Stokes/parabolic interface
problem with jump coefficients. The corresponding mixed finite element approximation is
analyzed for both semi and full discretization based upon the socalled nonconservative
ALE scheme. The stability and optimal convergence properties in the energy norm are
obtained for both schemes.
Numerical Analysis And Fluid Flow Modeling Of Incompressible NavierStokes Equations, Tahj Hill
Numerical Analysis And Fluid Flow Modeling Of Incompressible NavierStokes Equations, Tahj Hill
UNLV Theses, Dissertations, Professional Papers, and Capstones
The NavierStokes equations (NSE) are an essential set of partial differential equations for governing the motion of fluids. In this paper, we will study the NSE for an incompressible flow, one which density ρ = ρ0 is constant.
First, we will present the derivation of the NSE and discuss solutions and boundary conditions for the equations. We will then discuss the Reynolds number, a dimensionless number that is important in the observations of fluid flow patterns. We will study the NSE at various Reynolds numbers, and use the Reynolds number to write the NSE in a nondimensional form.
We will then ...
On Analytic Nonlinear InputOutput Systems: Expanded Global Convergence And System Interconnections, Irina M. Winter Arboleda
On Analytic Nonlinear InputOutput Systems: Expanded Global Convergence And System Interconnections, Irina M. Winter Arboleda
Electrical & Computer Engineering Theses & Disssertations
Functional series representations of nonlinear systems first appeared in engineering in the early 1950’s. One common representation of a nonlinear inputoutput system are ChenFliess series or Fliess operators. Such operators are described by functional series indexed by words over a noncommutative alphabet. They can be viewed as a noncommutative generalization of a Taylor series. A Fliess operator is said to be globally convergent when its radius of convergence is infinite, in other words, when there is no a priori upper bound on both the L1norm of an admissible input and the length of time over which the corresponding output ...
Piezoelectric Sensor Crack Detection On Airframe Systems, Kevin J. Lin
Piezoelectric Sensor Crack Detection On Airframe Systems, Kevin J. Lin
Theses and Dissertations
In 2008, the Department of Defense published a guidebook for a methodology named ConditionBased Maintenance Plus (CBM+) which capabilities include improving productivity, shortening maintenance cycles, lowering costs, and increasing availability and reliability. This push replaces existing inspection criteria, often conducted as nondestructive testing (NDT), with structural health monitoring (SHM) systems. The SHM system addressed utilizes guided Lamb waves generated by piezoelectric wafer active sensors (PWAS) to detect the existence, size, and location of damage from throughthickness cracks around a rivet hole. The SHM field lacks an experiment testing how small changes in receiver sensor distances affect damage detection. In addition ...
Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda
Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda
Theses and Dissertations
Highspeed Schlieren photography was utilized to visualize flow in the Air Force Research Laboratory Mach 6 Ludwieg tube facility. A 7° halfangle cone/flare model with variable nosetip radius and flare angle options was used in the study. Testing was performed at two driver tube pressures, generating freestream Reynolds numbers of 10.0x10^{6} and 19.8x10^{6} per meter. The variableangle flare portion of the model provided a method for adjusting the intensity of the adverse pressure gradient at the cone/flare junction. As expected from existing literature, boundary layer separation along the cone frustum occurred further upstream as ...
Wall Model Large Eddy Simulation Of A Diffusing Serpentine Inlet Duct, Ryan J. Thompson
Wall Model Large Eddy Simulation Of A Diffusing Serpentine Inlet Duct, Ryan J. Thompson
Theses and Dissertations
The modeling focus on serpentine inlet ducts (Sduct), as with any inlet, is to quantify the total pressure recovery and ow distortion after the inlet, which directly impacts the performance of a turbine engine fed by the inlet. Accurate prediction of Sduct ow has yet to be achieved amongst the computational fluid dynamics (CFD) community to improve the reliance on modeling reducing costly testing. While direct numerical simulation of the turbulent ow in an Sduct is too cost prohibitive due to grid scaling with Reynolds number, wallmodeled large eddy simulation (WMLES) serves as a tractable alternative. US3D, a hypersonic research ...
The Use Of 3D Highway Differential Geometry In Crash Prediction Modeling, Kiriakos Amiridis
The Use Of 3D Highway Differential Geometry In Crash Prediction Modeling, Kiriakos Amiridis
Theses and DissertationsCivil Engineering
The objective of this research is to evaluate and introduce a new methodology regarding rural highway safety. Current practices rely on crash prediction models that utilize specific explanatory variables, whereas the depository of knowledge for past research is the Highway Safety Manual (HSM). Most of the prediction models in the HSM identify the effect of individual geometric elements on crash occurrence and consider their combination in a multiplicative manner, where each effect is multiplied with others to determine their combined influence. The concepts of 3dimesnional (3D) representation of the roadway surface have also been explored in the past aiming to ...
Formulation And Implementation Of Iterative Method For Generating SpatiallyVariant Lattices, Manuel Fernando Martinez
Formulation And Implementation Of Iterative Method For Generating SpatiallyVariant Lattices, Manuel Fernando Martinez
Open Access Theses & Dissertations
The use of a matrixfree, memoryefficient approach to generate largescale spatially variant lattices (SVL) was explored. A matrixfree iterative SVL generation algorithm was formulated and then implemented with a tremendous memory reduction observed. The algorithm consists of solving firstorder central finitedifferences along the entirety of the problem space pointbypoint to obtain the grating phase function Φ(𝑠⃗) to which all desired spatially variant lattice properties are applied to. The algorithm was studied to identify key areas of data and task parallelism to exploit in heterogeneous computing systems consisting of clusters of central processing units (CPU) and graphics processing units (GPU ...
A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc, Nicholas Stegmeier
A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc, Nicholas Stegmeier
Electronic Theses and Dissertations
The importance of computing in the natural sciences continues to grow as scientists strive to analyze complex phenomena. The dynamics of turbulence, astrophysics simulations, and climate change are just a few examples where computing is critical. These problems are computationally intractable on all computing platforms except supercomputers, necessitating the continued development of efficient algorithms and methodologies in parallel computing. This thesis investigates the use of parallel computing and mathematical modeling in the natural sciences through several applications, namely computational fluid dynamics for impinging jets in mechanical engineering, simulation of biofilms in an aqueous environment in mathematical biology, and the solution ...
Pressure Versus Impulse Graph For BlastInduced Traumatic Brain Injury And Correlation To Observable Blast Injuries, Barbara Rutter
Pressure Versus Impulse Graph For BlastInduced Traumatic Brain Injury And Correlation To Observable Blast Injuries, Barbara Rutter
Doctoral Dissertations
"With the increased use of explosive devices in combat, blast induced traumatic brain injury (bTBI) has become one of the signature wounds in current conflicts. Animal studies have been conducted to understand the mechanisms in the brain and a pressure versus time graph has been produced. However, the role of impulse in bTBIs has not been thoroughly investigated for animals or human beings.
This research proposes a new method of presenting bTBI data by using a pressure versus impulse (PI) graph. PI graphs have been found useful in presenting lung lethality regions and building damage thresholds. To present the animal ...