Digital Commons Network^™

Influence Of Damping On Hyperbolic Equations With Parabolic Degeneracy, Katarzyna Saxton, Ralph Saxton

Mathematics Faculty Publications

This paper examines the effect of damping on a nonstrictly hyperbolic 2 x 2 system. It is shown that the growth of singularities is not restricted as in the strictly hyperbolic case where dissipation can be strong enough to preserve the smoothness of solutions globally in time. Here, irrespective of the stabilizing properties of damping, solutions are found to break down in finite time on a line where two eigenvalues coincide in state space.

An H1 Model For Inextensible Strings, Stephen C. Preston, Ralph Saxton

Mathematics Faculty Publications

We study geodesics of the H¹ Riemannian metric (see article for equation) on the space of inextensible curves (see article for equation). This metric is a regularization of the usual L² metric on curves, for which the submanifold geometry and geodesic equations have been analyzed already. The H¹ geodesic equation represents a limiting case of the Pochhammer-Chree equation from elasticity theory. We show the geodesic equation is C^∞ in the Banach topology C¹ ([0,1], R²), and thus there is a smooth Riemannian exponential map. Furthermore, if we hold one of the curves fixed, …

Blow-Up Of Solutions To The Generalized Inviscid Proudman-Johnson Equation, Alejandro Sarria, Ralph Saxton

Mathematics Faculty Publications

For arbitrary values of a parameter --- finite-time blowup of solutions to the generalized, inviscid Proudman Johnson equation is studied via a direct approach which involves the derivation of representation formulae for solutions to the problem.

Critical Buckling Loads Of The Perfect Hollomon’S Power-Law Columns, Dongming Wei, Alejandro Sarria, Mohamed Elgindi

Mathematics Faculty Publications

In this work, we present analytic formulas for calculating the critical buckling states of some plastic axial columns of constant cross-sections. The associated critical buckling loads are calculated by Euler-type analytic formulas and the associated deformed shapes are presented in terms of generalized trigonometric functions. The plasticity of the material is defined by the Holloman’s power-law equation. This is an extension of the Euler critical buckling loads of perfect elastic columns to perfect plastic columns. In particular, critical loads for perfect straight plastic columns with circular and rectangular cross-sections are calculated for a list of commonly used metals. Connections and …

Some Generalized Trigonometric Sine Functions And Their Applications, Dongming Wei, Yu Liu, Mohamed B. Elgindi

Mathematics Faculty Publications

In this paper, it is shown that D. Shelupsky's generalized sine function, and various general sine functions developed by P. Drabek, R. Manasevich and M. Otani, P. Lindqvist, including the generalized Jacobi elliptic sine function of S. Takeuchi can be defined by systems of first order nonlinear ordinary differential equations with initial conditions. The structure of the system of differential equations is shown to be related to the Hamilton System in Lagrangian Mechanics. Numerical solutions of the ODE systems are solved to demonstrate the sine functions graphically. It is also demonstrated that the some of the generalized sine functions can …

On The Global Solvability Of A Class Of Fourth-Order Nonlinear Boundary Value Problems, M.B.M. Elgindi, Dongming Wei

Mathematics Faculty Publications

In this paper we prove the global solvability of a class of fourth-order nonlinear boundary value problems that govern the deformation of a Hollomon’s power-law plastic beam subject to an axial compression and nonlinear lateral constrains. For certain ranges of the acting axial compression force, the solvability of the equations follows from the monotonicity of the fourth order nonlinear differential operator. Beyond these ranges the monotonicity of the operator is lost. It is shown that, in this case, the global solvability may be generated by the lower order nonlinear terms of the equations for a certain type of constrains.

Travelling Wave Solutions Of Burgers' Equation For Gee-Lyon Fluid Flows, Dongming Wei, Ken Holladay

Mathematics Faculty Publications

In this work we present some analytic and semi-analytic traveling wave solutions of generalized Burger' equation for isothermal unidirectional flow of viscous non-Newtonian fluids obeying Gee-Lyon nonlinear rheological equation. The solution of Burgers' equation for Newtonian flow as a special case. We also derive estimates of shock thickness for non-Newtonian flows.

Impaired Object Tracking In Children With Chromosome 22q11.2 Deletion Syndrome, Margarita H. Cabaral, Elliott A. Beaton, Joel Stoddard, Tony J. Simon

Psychology Faculty Publications

Background:

Chromosome 22q11.2 Deletion Syndrome (22q11.2DS) occurs in approximately 1:4,000 live births with a complex and variable presentation that includes medical, socioemotional and psychological symptoms with intellectual impairment. Cognitive impairments in spatiotemporal and visuospatial attention have also been reported. However, maintenance of selective attention to dynamic and interacting objects has not been systematically investigated in children with 22q11.2DS.

Methods:

We used a multiple object tracking task to assay capacity and resolution performance of children with 22q11.2DS aged 7 to 14 years versus age-matched typically developing (TD) peers.

Results:

Children with 22q11.2DS but not TD children demonstrated impaired performance when task …

Do Not Resuscitate And Other Imperatives, Stacy B. Harrison

All NMU Master's Theses

No abstract provided.

Classification Of Mental Illness In The 18th Century: A Comparison Of The Nosologies Of Carl Linnaeus, Francois Bossier De Sauvages, Rudolpho Vogel And William Cullen, Heather Ann Munsche

All NMU Master's Theses

No abstract provided.

The Legendre Transform Of The Holst Action, Caixia Gao

Electronic Theses and Dissertations

I start with a short introduction on 3+1 ADM form and the tetrad form of General Relativity, then I review the Legendre transform of the Einstein-Hilbert action and the Palatini action. The Holst action is a generalization of the Palatini action by including a topological term. I derive Ashtekar's connection form directly from this action by doing the Legendre transformation rather than by a canonical transformation in the usual phase space. This is done in both Remmanian signature with half-flat connection and Lorentz signature with general Barbero-Immirzi parameter.

Functional Morphology Of The Sphyrnid Shark Cephalofoil: An Assessment Of The Hydrodynamic Lift Hypothesis Using Computational Fluid Dynamics, Matthew K. Gaylord

Electronic Theses and Dissertations

The hammerhead sharks (Family: Sphyrnidae) are all characterized by a conspicuous lateral expansion and dorsoventral flattening of the head forming a structure known as a cephalofoil, however, there is substantial morphological variation within the clade. Many theories have been proposed regarding the functional aspects of this structure. One of these is that it may produce beneficial dynamic lift as the shark swims (in similar fashion to the cambered wings found on many modern-day aircraft). As sharks do not possess a swim bladder, part of their energy intake is expended on simply maintaining vertical station in the water column. If indeed …

The Impact Of The User-It Artifact Interaction On Technology Implementation And Value: Mobile Social Networking And Mobile Social Capital, Donghyun Kim

Electronic Theses and Dissertations

Despite investment and cutting-edge features, the majority of new mobile phone subscribers have adopted low-cost handsets instead of the latest mobile devices (Karjaluoto et al., 2005). According to the U.S. Census Bureau report, only 37% of cell phone users selected a smartphone in 2007. The Census Bureau forecasted the figure would increase by less than 10% in 2008. However, only 24% of cell phone users owned a smartphone in 2010, 27 % in 2011 and 30% in 2012. Therefore, the purpose of this study is to propose a conceptual model of the impact of mobile social capital on mobile networks …

Multi-Configurational Investigation Of Thermolytic Pathways Of Highly Strained Ring Systems, Jeffrey Dwayne Veals

Electronic Theses and Dissertations

The isomerization pathways of model high energy structures are of interest because of their relation to high energy density fuels. Electron resonance has been found to greatly affect the relative activation barriers for several isomerization pathways, and the major goal of this research is to accurately describe its role in determining the relative barriers for strain energy release pathways. This research is centered around the potential energy surfaces (PES's) for ? bond breaking and ? bond rotation in these highly strained structures. Of particular interest was how would resonance and or electronegativity affect the allowed/disallonature of the activation barriers in …

Stochastic Models For Evolutionary Genetic Problems, Wei Liao

Electronic Theses and Dissertations

Two stochastic models are designed for answering evolutionary genetic problems. The first study shows that inbreeding-environment interactions increase extinction risk. The second research demonstrates that 1) the carrying capacity and initial population growth rate is critical to determine the population persistence time; 2) increasing the advantageous mutation rate reduces the extinction risk although its effects are usually shadoby population size and fitness; 3) the new mutation correlation among environments rises during the evolution process, but it has compromised effects on population fate. Being able to accurately estimate the persistence time of populations of endangered plants and animals is central to …

Selection Criteria For Identifying Gifted And Talented Minority Students In Grades One Through Five In Central Mississippi, Tracey Bell

Electronic Theses and Dissertations

The purpose of this study was to (a) evaluate and discuss strengths and weaknesses in the current system of identifying gifted students and (b) investigate the effectiveness of using the Naglieri Nonverbal Abilities Test to identify underrepresented and gifted minority students in grades one through five in Central Mississippi. The study consisted of 12 students who were screened using the traditional method of testing and 53 students who were screened using the alternative method of testing. This study attempted to explore strengths and weaknesses in the current system's minority gifted identification process. The alternate screening process did not demonstrate the …

Multidoman Piezo-Ceramic Cantilever, David Paul Sedorook

Electronic Theses and Dissertations

PZT-5H is a ferroelectric and piezoelectric material that has many applications that are the subjects of current research. As a ferroelectric, PZT-5H has a permanent electrical polarization that arises from ferroelectric domains. In this thesis, numerical simulations were conducted via the well know Finite Element Method of several types of piezoelectric cantilevers that were made of PIC-181, a high quality PZT-5H made in Germany. Single crystal cantilever models with multiple polarization vectors were investigated with Q factors ranging from Q = 50 to Q = 1200, where the acoustical displacements were calculated. Further, the displacements were calculated for a multidomain …

Electrochemistry, Transport Properties And Electronic Spectroscopy Of Lanthanide Solutes In Bis(Trifluoromethylsulfonyl)Imide-Based Ionic Liquids, Yunfeng Pan

Electronic Theses and Dissertations

No abstract provided.

Diy Pr: How Independent Music Artists Use Online Social Networks For Public Relations Purposes, Martina Lawless

Theses

Significance of the study: Independent musicians are a huge part of the Irish music industry and yet they are the part that do not have the backing of a record label. This means independent musicians need to look at cheap or even free ways to promote themselves to existing fans and potential new fans. With the emergence of social networks musicians both signed and independent have the tools necessary to engage in a new form DIY PR. The purpose of this study is to look at the different ways that social networks have helped musicians in recent years, but also …

An Investigation Of Discontinuous Specular Surfaces Using Non-Contact Techniques In Line Monitoring., Kiryl Kekukh

Theses

Surface metrology by structured light projection has been a standard technique in industry for many years. However, when the surface under test is reflective or specular it is impossible to use this particular method. In this instance a modified procedure called "Fringe Reflection” is used. In this technique patterns similar to structured light are projected onto a screen, located remotely from the surface, and fringe patterns, reflected via the surface, are recorded using a CCD-camera. To recover the range data of such a surface from a set of images taken, a phase unwrapping algorithm is used. For the purpose and …

The Effects Of Climate On The Growth Of Winter Wheat And Spring Barley In An Irish Context, Adrian Kennedy

Theses

The climate of earth is always changing due to natural events, however it is thought that the rapid warming period currently taking place is primarily due human activity to (environmental protection agency 2012). Climate change is altering the environment and this will have consequences for agriculture (Teagasc publications 2012). In this study we examine the relationship between weather and the yield of winter wheat and spring barley in an Irish context using data gathered from 2004-2010 at the Teagasc Oak Park research centre in Carlow. The data was analysed using a mixed effect model to test which if any weather …

Morality In The Virtual Space: Applying Moral Philosophy To Digital Worlds, James O'Sullivan

Theses

Since the turn of the century and the dawn of the digital age, online communities have witnessed significant growth in their importance. Significant numbers of virtual environments now exist, within which millions of individuals interact socially and economically, engaged fully in what is equivalent to a physical encounter, the only differences being the virtual representations through which they interact, and the physical security that this representation affords them. Though physically absent, individuals are fully engaged psychologically, and thus open to the same ethical dilemmas presented through reality. Application of real-world moral codes is encumbered by the existence of what 1 …

Quantum-Dot Mode-Locked Lasers With Optical Injection, Tatiana Habruseva

Theses

In this thesis novel stabilised ultra-fast pulse sources for a range of practical applications have been developed.

Semiconductor mode-locked lasers have much promise as sources of short, low- jitter, high repetition rate pulses. Development of stabilised semiconductor sources is in a great demand for applications, such as optical telecommunications, frequency metrology, optical sampling and clock recovery. Arbitrary waveform generation, wavelength-division and orthogonal-frequency-division multiplexing techniques need wide stable frequency combs with low phase noise. A low level of pulse-to-pulse timing fluctuations is essential for clock recovery, optical sampling and optical time- division multiplexing. Therefore, this work dealing with the development of …

Numerical Modelling Of The River Bandon, Stephen Finn

Theses

Numerical modelling involves the use of data from the physical environment and mathematical equations to achieve predictive solutions to many engineering problems including for river engineering. The field data is surveyed, sampled, recorded and tested before it is entered into the numerical modelling program for analysis. The numerical modelling program contains various mathematical equations that solve the data that has been entered. Numerical modelling is an important tool for predicting the consequences of future events. It can be used for predicting the damage of a 1 in 100 year flood event in a river system. Numerical modelling is used by …

Effects Of Cyclic Loading On Offshore Foundation Systems, Shane Browne

Theses

A brief description of the various offshore foundation systems currently available is provided in this report, including the advantages and disadvantages for each system and water depth in which they can be used. These foundation types include floating structures, jacket structures, gravity base structures and the monopile foundation, on which this research specifically focuses.

The monotonic lateral loading of the monopile structure is also examined and the reasons why monotonic testing is required are highlighted, along with the potential analysis that can be generated to improve the design of the monopile foundation. A review of previous test programmes for monopiles …

Dynamics Of Passively Mode-Locked Lasers With Optical Injection, Natalia Rebrova

Theses

Semiconductor passively mode-locked (ML) lasers are of particular interest due to their compactness, cost-efficiency and ease of operation. However, outside optimal parameter range these lasers suffer waveform instabilities, large chirp and significant timing jitter, which makes them ineffective in highspeed applications. In this work we model monolithic passively mode-locked lasers using delay differential equations. We study laser dynamics under external optical injection. We demonstrate that optical injection can improve the properties of mode-locked lasers in terms of the time-bandwidth product, noise and pulse stability. Also this work provides the estimate of locking range for a passively ML semiconductor laser subjected …

Development Of Mass Spectrometric Methods For The Analysis Of Serotonin And Related Compounds In Biological Matrices, Merisa Moriarty

Theses

Serotonin is a major neurotransmitter in the brain and affects various functions both in the brain and in the rest of the body. It has been linked to depression, migraines, and aggression, as well as many psychiatric disorders including schizophrenia, dementia and anorexia nervosa. It also has been associated with conditions like Alzheimer’s disease along with other neurotransmitters such as dopamine.

The aim of this research project is to develop various mass spectrometric methods for the analysis of serotonin, dopamine and similar indoles in both urine and serum matrices. This thesis provides extensive reviews detailing a general overview of serotonin …

Theoretical And Experimental Analysis Of Mems Ohmic Switch Design And Control For Reliability Improvement, Cuong Do

Theses

MEMS devices are micromechanical components fabricated using semiconductor fabrication technologies. With advanced functionalities and miniaturization, MEMS devices are being employed in a wide variety of applications, especially in mobile networks. The MEMS ohmic switch is one of the most promising MEMS devices and has the same principle of a mechanical moving switch to manipulate an electrical signal. Due to the existence of mechanical movement, and its compactness, reliability issues have been observed as the main barrier to commercialisation.

This thesis addresses the key issue of reliability in the rapidly expanding area of MEMS. In particular, MEMS ohmic switches are considered. …

Wireless Sensor Networks: Empowering Reliable, Realtime & Resource Efficient Communication For Cyber-Physical Applications, Jasvinder Singh

Theses

Since their inception, Wireless Sensor Networks (WSNs) have been successfully employed as low-rate data gathering networks in numerous monitoring applications. Recently, a new domain of WSNs applications, known as Cyber-Physical Systems (CPS) has started attracting significant attention world-wide. In these applications, monitoring only the state of the physical system (process or environment) is not sufficient, the system must respond to the sensed events/data within certain time constraints by performing actions upon the physical entity. It is expected that in approaching years, WSNs will be integrated in a myriad of CPS applications, for example high confidence medical systems, assisted living, traffic …

In Memory Of Dr. Edward John Kaufman, University Relations

Campus News Archive

No abstract provided.