Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 30 of 87
Full-Text Articles in Entire DC Network
Boat Wake Attenuation Through Artificial Vegetation - A Case Study From Peche Island, Jamie Kathryn Lilly
Boat Wake Attenuation Through Artificial Vegetation - A Case Study From Peche Island, Jamie Kathryn Lilly
Electronic Theses and Dissertations
The use of nature-based solutions and engineering ideas has sparked interest in the value of vegetated shorelines for protecting against erosion. However, there is a lack of field data, and more research is needed to understand how effective vegetation is in reducing the impact of wind waves and boat wakes. The difference in period between wind waves and boat wakes suggests that they may be attenuated differently, requiring further study to determine the optimal management design. The purpose of this study is to quantify the ability of artificial vegetation to attenuate boat wakes and calculate the drag coefficient for model …
Resonance Raman Spectral Calculations Of Organic Semiconductor Molecules, Mohammadamin Torabi
Resonance Raman Spectral Calculations Of Organic Semiconductor Molecules, Mohammadamin Torabi
Electronic Theses and Dissertations
Organic semiconductors have received a great deal of attention in recent years due to their optoelectronical properties and their potential applications in industry. In this thesis, resonance Raman calculations of a family of organic semiconductor dyes: pery-lene tetracarboxylic diimides (PTCD) derivatives, are presented. Also the UV/vis, infrared and normal Raman spectra, structures and molecular orbitals, excitation ener- gies, dipole moments, (hyper) polarizabilities and charge population analyses of these molecules are calculated. The calculations in this thesis are performed using a Time- Dependent Density Functional Theory (TDDFT) method, and for that, the Amsterdam Density Functional program package (ADF2009) is used. The …
Excitation And Ionization Of 6li Ions Following Beta-Decay Of 6he., Eva Schulhoff
Excitation And Ionization Of 6li Ions Following Beta-Decay Of 6he., Eva Schulhoff
Electronic Theses and Dissertations
6He beta-decays into 6Li causing an electronic rearrangement of the final 6Li atom. The calculations involve expanding the initial state of 6He in terms of a complete set of final states of 6Li. Correlated Hylleraas-like wave functions were used to create a pseudospectrum, which spans both the bound and continue states of 6Li. The sudden approximation with neglected recoil was used. Starting from the 1 1S1 and 2 3S1 initial configurations, the transitions to the final 6Li bound states, as well as the total probabilities of single and double ionization were calculated. The transition probabilities to bound states were compared …
Development Of A Coaxial Electron-Laser Beam Collision Experiment, Justin Teeuwen
Development Of A Coaxial Electron-Laser Beam Collision Experiment, Justin Teeuwen
Electronic Theses and Dissertations
An electron optical system which propagates an electron beam coaxially with a laser was designed, developed and tested. Greatly improved signal rates were obtained when excitation of various target species under electron impact was studied. Measurements of excitation in nitrogen, specifically the (0,0) second positive band of N2 and (0,1) first negative band of N2 are made and compared with well-known previous results to calibrate the system. Emission cross section measurements were made by direct excitation of a number of argon transitions, including the 3p5 4p [1 1/2] (J=1) -> 3p5 4s [1/2] (J=0) transition. Comparison with previous results showed …
Optical Properties Of Nanostructures And Applications To Surface-Enhanced Spectroscopy, Daniel Ross
Optical Properties Of Nanostructures And Applications To Surface-Enhanced Spectroscopy, Daniel Ross
Electronic Theses and Dissertations
Metallic nanoparticles, in particular silver and gold nanostructures, are at the centre of the development of plasmon enhanced optical signals. There is a flurry of activities in the fabrication and testing of these nanostructures, especially in surface enhanced Raman scattering (SERS) and surface enhanced-infrared absorption (SEIRA), the two branches of surface-enhanced vibrational spectroscopy. The need to develop an understanding of this general subject matter for practicing spectroscopists cannot be questioned. This work is a unique undertaking intended to examine some of the elements that give rise to surface enhanced spectroscopy. The optical properties of nanoparticles are discussed in detail, beginning …
Quantum Phase Transition In Triple Quantum Dot System And Its Consequences On Transport, Behnam Javanparast
Quantum Phase Transition In Triple Quantum Dot System And Its Consequences On Transport, Behnam Javanparast
Electronic Theses and Dissertations
In this thesis, possibility of quantum phase transition in systems composed of quantum dots will be studied. We also investigate the consequence of this phase transition on transport. We particularly consider a triple quantum dot system (three quantum dots sitting on the corners of an equilateral triangle) coupled to three leads symmetrically. To probe quantum phase transition we utilize slave-boson mean-field theory and to investigate transport properties we use scattering formalism. We detect a competition between Kondo and non-Kondo regime in this system. This competition affects transport in a way that conductance and noise will become zero when the non-Kondo …
Real Time Physical Analysis Of Consolidation Process For Low Pressure Gas Dynamic Spray, Mark Lubrick
Real Time Physical Analysis Of Consolidation Process For Low Pressure Gas Dynamic Spray, Mark Lubrick
Electronic Theses and Dissertations
The gas dynamic spray process is studied via acoustic methods with the main focus being on developing an online system to monitor the process as it occurs. Elastic modulus measurements of the coatings are determined from the sound velocity and porosity. The resulting data is than compared against a minimum contact area model that is developed to describe the bonds that are formed between particles. The results show a good fit to the theoretical considerations of the model. Different transducer designs are considered leading to the use of a multi-element flat transducer for the online monitoring. Online measurements show that …
Molecular Studies Using Resonance Enhanced Multiphoton Ionization., Jeffrey Matos
Molecular Studies Using Resonance Enhanced Multiphoton Ionization., Jeffrey Matos
Electronic Theses and Dissertations
Nitric oxide was studied using the techniques of laser induced fluorescence and resonance enhanced multiphoton ionization. A supersonic expansion beam consisting of nitric oxide and argon gas was crossed with a laser beam. The A2Sigma+ state of nitric oxide was used as an intermediate in the ionization process. Total fluorescence from the A2Sigma + state of nitric oxide was collected while the laser source was scanned from 225.5 nm to 226.9 run to produce an excitation spectrum. Time-of-flight mass spectra of nitric oxide, argon, and nitrogen were collected to verify the ions produced and to calibrate a newly constructed time-of-flight …
On Hawking Radiation And The Casimir Effect., Darragh Rooney
On Hawking Radiation And The Casimir Effect., Darragh Rooney
Electronic Theses and Dissertations
The purpose of this thesis is to understand the quantum vacuum in curved space-time by comparing the phenomenon of Hawking radiation with the Casimir effect. I begin with an exposition on the semiclassical approximation, as yet our best framework for understanding the curved vacuum, with additional preliminaries regarding the nature of particles and vacua in general. I discuss the Schwarzschild black hole, and derive the Hawking particle flux. Hawking radiation is viewed as a kinematical effect, which I compare to the case of mirrors moving in flat space-time. I move on to the Casimir effect: I discuss the classic case …
Hardness Characteristics Of Cobalt/Chromium And Nickel/Chromium By Electrodeposition Or Electroless Deposition., Wei Chen
Electronic Theses and Dissertations
This work is a report on the study of hardness characteristics of Nickel and Cobalt thin films with and without chromium powder. The coatings are prepared by electrodeposition or electroless deposition [1]. The dispersed phase was Cr particles in a concentration of 50 to 100 mg/l added in the electrolyte, magnetically stirred in 400 rev./min.-1 for a few minutes then stopped for a certain period of time. Purpose of this is to let bigger particles settle down on the bottom and only the finest particles floating in the bath evenly. It is shown that many factors contribute to the quality …
Tests Of Cusp Conditions And Integral Recursion Relations For Helium Wave Functions., Levant Inci
Tests Of Cusp Conditions And Integral Recursion Relations For Helium Wave Functions., Levant Inci
Electronic Theses and Dissertations
The aim of this work is to apply the Kato cusp conditions to Hylleraas type variational wave functions and to test the numerical stability of the integral recursion relations for helium and helium-like ions. The Kato cusp conditions are applied from helium (Z = 2) up to argon (Z = 18), then the exact cusp values are compared with the cusp values from two basis set and three basis set Hylleraas type wave functions. Integral recursion relations are calculated for different powers of r1, r2, and r 12 and also for different nonlinear parameters (alpha, beta).Dept. of Physics. Paper copy …
High Precision Theoretical Study Of The Hydrogen Ion., Mark Michael Cassar
High Precision Theoretical Study Of The Hydrogen Ion., Mark Michael Cassar
Electronic Theses and Dissertations
A study of the hydrogen molecule-ion H+2 is presented. The purpose is to show that a carefully modified, doubled basis set in the standard Hylleraas coordinates provides an excellent, yet straightforward, description of this ion without recourse to approximation methods. Three non-linear parameters are used so that distance scales may be set independently for all three radial coordinates r 1, r2 and r12. Vibrational modes are effectively accounted for by including only high powers of the inter-proton coordinate r12. High precision variational calculations are carried out for the 1 1 S ground state, and the first two excited states---2 1S …
Second Order Effects Of Structural And Material Damage On Ultrasonic Waves., Brian E. O'Neill
Second Order Effects Of Structural And Material Damage On Ultrasonic Waves., Brian E. O'Neill
Electronic Theses and Dissertations
Damage mechanics is a relatively new and powerful approach to the analysis of material degradation and failure. The idea is to build a continuum model of a solid containing a distribution of microcracks. Such a model, relying on the thermodynamics and statistical mechanics of microcracks, very naturally ties into other continuum models of solids, including acoustic and elastic models. In this dissertation, the impact of material and structural damage is investigated, with an emphasis on the relation between this effect and specific second order ultrasonic effects. The investigation has two main streams. The first, more experimental stream involves damage in …
Hyperfine Structure For The Rydberg States Of Helium-3., Qixue. Wu
Hyperfine Structure For The Rydberg States Of Helium-3., Qixue. Wu
Electronic Theses and Dissertations
A comprehensive study is made of the hyperfine structure of the helium isotope 3He for all states up to n = 10 and L = 7. High precision values of the hyperfine structure parameters CSS', DS, and ESS' are calculated using the doubled-basis-set Hylleraas-type wave functions developed by Drake. In this calculation, the singlet-triplet states mixing, the Breit relativistic, QED and finite nuclear size effects are included. Hyperfine splittings and hyperfine shifts have been calculated by diagonalizing the complete fine and hyperfine interaction matrix. Our results nicely agree with the available experimental ones. One of the applications of the calculated …
Improved Strategies For Variational Calculations For Helium, R. A. Nistor
Improved Strategies For Variational Calculations For Helium, R. A. Nistor
Electronic Theses and Dissertations
The aim of this work is to apply trial functions constructed from Hylleraas functions with three independent sets of nonlinear scale factors to variational calculations for helium and helium-like ions. The ground state and low-lying Rydberg energy levels of these ions have been calculated to several orders of magnitude greater accuracy than previous work in this area while using an equal, or in most cases, a reduced number of basis functions. Each of the three sectors of the basis set is found to describe a different scale of coordinate space corresponding to the asymptotic, intermediate, and close-ranged distances between particles. …
Photoconductivity And Acoustic Wave Interaction With Charge Carriers In Cadmium Sulfide., Wesley Arthur
Photoconductivity And Acoustic Wave Interaction With Charge Carriers In Cadmium Sulfide., Wesley Arthur
Electronic Theses and Dissertations
The principle focus of this investigation is ultrasonic acoustic wave interaction with charge carriers in cadmium sulfide. In order to facilitate this study, however, effort is spent to better characterize the metastable crystal conductivities that were observed in preliminary research. Specifically, an experiment is carried out to determine the behaviour of three instabilities over time periods of one hour. Upon analysing the results of this procedure, the effect of temperature on CdS conductivity is considered. In the portion of thesis paper regarding acoustics, preliminary endeavours are made to observe some of the fundamental phenomenon associated with the acousto-electric effect. Wave …
Electron-Cluster Interactions: Excitation Of Neutral Fragments In Rare Gases And Simple Molecules., Charles Patrick Malone
Electron-Cluster Interactions: Excitation Of Neutral Fragments In Rare Gases And Simple Molecules., Charles Patrick Malone
Electronic Theses and Dissertations
The presented work on electron-cluster interactions utilizes mass and translational spectroscopic techniques that have traditionally been applied to atomic and molecular targets.
Electron Collision Studies Of Cesium Using A Magneto-Optical Trap., John Alexander. Macaskill
Electron Collision Studies Of Cesium Using A Magneto-Optical Trap., John Alexander. Macaskill
Electronic Theses and Dissertations
Experiments involving a magneto-optical trap (MOT) as the target in electron impact cross section studies were carried out. The use of a MOT allows the kinematic properties of the target atoms, and their electronic states, to be controlled via operating parameters of the MOT's lasers. A MOT is capable of saturating the excited state of a gaseous target of atoms and provides a unique opportunity to measure exotic collision processes. Measurements use a trap-loss technique to relate the loss rate of atoms from the trap due to electron interactions to a collision cross section. Total scattering cross section measurements are …
Experimental Study And Theoretical Modelling Of Ultrasonic Wave Propagation In Resistance Spot Welds., Andriy M. Chertov
Experimental Study And Theoretical Modelling Of Ultrasonic Wave Propagation In Resistance Spot Welds., Andriy M. Chertov
Electronic Theses and Dissertations
The theoretical and experimental study of resistance spot weld quality has a long history. Since the invention of the method manufacturers are concerned about the means of quality assurance of the joints. One of the most promising current techniques of quality inspection is the real time ultrasonic nondestructive evaluation. In such a system the acoustic signals are sent through the spot weld during welding and then analyzed to predict the size of the future joint. In spite of its purely industrial application and seemingly easy setup the problem involves several complicated mechanisms to be described using a physical-mathematical approach. This …
Ultrasonic Propagation Across A Thin Layer Between Two Bulk Media: Theory, Computer Simulation And Experiment., Jeffrey. Sadler
Ultrasonic Propagation Across A Thin Layer Between Two Bulk Media: Theory, Computer Simulation And Experiment., Jeffrey. Sadler
Electronic Theses and Dissertations
This thesis describes the changes in the reflected and transmitted acoustic waves due to the addition of a thin layer (thickness much less than an acoustic wavelength) between two half-spaces of material. The restriction of the thin layer allows one to combine perturbation methods with the standard fully bonded boundary conditions at each interface and derive a set of equations where one no longer is concerned with the acoustic waves internal to the thin layer. This approach allows one to further examine the cases of a nonlinear thin layer, an anisotropic thin layer, and a thin layer with combined anisotropy …
Electron Impact Excitation Studies Of Unstable Atomic Species., Ady Kamel. Abdellatif
Electron Impact Excitation Studies Of Unstable Atomic Species., Ady Kamel. Abdellatif
Electronic Theses and Dissertations
The polarization of Balmer-alpha radiation excited in collisions of electrons with atomic hydrogen is presented for an electron energy range from threshold to 1000 eV. Measurements are in good agreement with calculations carried out using either convergent-close-coupling or R-matrix with pseudo-states approaches. Cascade is demonstrated to have a significant effect. Balmer-alpha excitation function data are also presented. A previous measurement of the polarization of Balmer-alpha following dissociative excitation of H2 by electrons is confirmed and extended. The electron impact excitation spectrum of atomic and molecular nitrogen in the VUV range (800 A--1800 A) is presented. The excitation functions of the …
Modeling And Optimization Of Non-Phased Two-Dimensional Ultrasonic Arrays., Alexey A. Denisov
Modeling And Optimization Of Non-Phased Two-Dimensional Ultrasonic Arrays., Alexey A. Denisov
Electronic Theses and Dissertations
Ultrasonic image acquisition with non-phased 2D arrays is a relatively new method in NDE inspection. Historically, ultrasonic array development progressed mostly in the medical imaging where phased arrays found a great application. However, in the field of NDE inspection of metals, heavy plastics and composites, and many other materials the applicability of phased arrays is often restricted due to physical limitations. On the other hand, using versatile systems with mechanical scanning is not always convenient. Therefore, non-phased arrays of independent elements have a strong potential for becoming a valuable tool for rapid ultrasonic image acquisition in the industrial environment as …
Laser Induced Fluorescence Studies Of Molecular Dissociation By Electron Impact., Tarek Hussein. Harb
Laser Induced Fluorescence Studies Of Molecular Dissociation By Electron Impact., Tarek Hussein. Harb
Electronic Theses and Dissertations
Laser Induced Fluorescence (LIF) techniques have been used to study the OH (X) and OD (X) radicals produced following electron impact dissociation of water, methanol, and heavy water. Impact energies ranged from the important near threshold region (<10 eV) up to 300 eV. A magnetically collimated electron beam has been used for this purpose. Absolute dissociation cross section measurements for the production of the OH (X) and OD (X) states have been obtained for the first time and reveal that this dissociation channel is a major contributor to the overall cross section for electron scattering. At 75 eV, the maximum value for the production of OH (X) from dissociation of water is 2.1 x 10-16 cm2. The cross section shape reveals that dipole allowed transitions are the dominant channels from which the OH (X) molecules are produced. The OD (X) from heavy water was studied as well to check for any isotopic effects. The OD (X) dissociation cross section was put on absolute scale by comparing to the cross section of that of water. A cross section ratio, sigmaH2O/sigma D2O = 0.9 was obtained. Finally comparison of the signal from electron impact dissociation of methanol to that of water enabled us to put the production of OH (X) fragments on an absolute scale. The value obtained was sigmaCH3OH/sigma H2O = 0.7. Cross section data and OH (X) rotational distributions from the different target molecules revealed significant details about the dissociation mechanisms and pathways.Dept. of Physics. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .H365. Source: Dissertation Abstracts International, Volume: 64-01, Section: B, page: 0268. Adviser: J. W. McConkey. Thesis (Ph.D.)--University of Windsor (Canada), 2002.
O((1)S) Metastable Production From Electron Impact Dissociative Excitation Of Water, Deuterium Oxide And Nitric Oxide., Joseph Macarthur. Derbyshire
O((1)S) Metastable Production From Electron Impact Dissociative Excitation Of Water, Deuterium Oxide And Nitric Oxide., Joseph Macarthur. Derbyshire
Electronic Theses and Dissertations
Using a solid Xe matrix upon a cold finger, at temperatures less than 77 K, O(1S) metastables produced from electron impact dissociative excitation of H2O, D2O, and NO were observed. From time-of-flight observations, total released kinetic energy spectra for the dissociative channels were ascertained. Threshold energies for dissociative channels were measured. Using the relative flow technique [Trajmar et al. (1996)], cross sections for the production of O(1S) from electron impact dissociation of H2O and D2O were made absolute by comparison with cross sections for O(1S) production from electron impact dissociation of CO2. In the case of H2O/D2O, the dissociative channels …
Plane Electromagnetic Waves In Layered Periodic Dielectric Structures., Gregory V. Morozov
Plane Electromagnetic Waves In Layered Periodic Dielectric Structures., Gregory V. Morozov
Electronic Theses and Dissertations
Several analytic methods are used to derive and discuss analytic expressions for electromagnetic wave fields in finite one-dimensional layered structures. A new modification is obtained for the so-called multiple reflection method. Special attention is given to layered periodic dielectric structures. The systematic dependence of the reflection coefficient on the parameters characterizing this type of structure is studied in detail, using the two-layered periodic dielectric structure as a typical example. A general method for the construction of the Green's function for finite one-dimensional layered structures is developed. The sum of the total Neumann (Born) series is calculated for sufficiently simple cases …
Applications Of The Pauli Algebra And Other Geometric Algebras., Shazia. Hadi
Applications Of The Pauli Algebra And Other Geometric Algebras., Shazia. Hadi
Electronic Theses and Dissertations
Relationships among the complex numbers, quaternions, and the Pauli algebra are developed by presenting them as geometrical (Clifford) algebras. Rotations are examined using both quaternions and the Pauli algebra, and in particular, algorithms that are used in three-dimensional simulations and video games are formulated in the Pauli algebra. Relativity is presented using a number of formalisms, and the treatment of De Leo and Rotelli is clarified. The relationship between spinors and spacetime vectors is explored using the Pauli algebra. Dirac theory is exhibited using the Pauli algebra, and neutrino oscillations are discussed.Dept. of Physics. Paper copy at Leddy Library: Theses …
An Algebraic Basis For The Standard-Model Gauge Group., Gregory James. Trayling
An Algebraic Basis For The Standard-Model Gauge Group., Gregory James. Trayling
Electronic Theses and Dissertations
A geometric approach to the standard model in terms of the Clifford algebra Cℓ7 is advanced. The gauge symmetries and charge assignments of the fundamental fermions and the Higgs boson are seen to arise uniquely from a simple geometric model involving only four extra space-like dimensions. A key feature of the model is its use of double-sided operations on the algebraic spinors. Transformations separate naturally into left-sided or "exterior", and right-sided or "interior" types. The exterior transformations include those of the Poincare and SU(2) L groups, the interior ones include those of SU(3) C, and a unique double-sided form of …
Hardness Characteristics In Electrodeposited Copper/Nickel Multilayer Systems., Li. Zhaojiang
Hardness Characteristics In Electrodeposited Copper/Nickel Multilayer Systems., Li. Zhaojiang
Electronic Theses and Dissertations
Multilayered Cu/Ni thin films were grown epitaxially on copper substrate using electrodeposition method. The multilayers possess coherent interfaces with well-defined satellites surrounding the main Bragg peaks in the X-Ray diffractograms. Hardness values greater than those of the constituent materials, by a factor of two or better, were found. Also, a Hall-Petch type relationship between hardness and superlattice periodicity, that is, hardness is in proportion to the inverse of the square root of the superlattice periodicity, is determined for superlattice periodicity in the range of about 40 to 80 angstroms. When nickel thickness is fixed at about 50 angstroms, hardness is …
Calculation Of Hyperfine Shifts Of 2s And 2p States Of Heliumlike Atoms Up To Z = 10., Limin. Pan
Calculation Of Hyperfine Shifts Of 2s And 2p States Of Heliumlike Atoms Up To Z = 10., Limin. Pan
Electronic Theses and Dissertations
The hyperfine shifts of 2S and 2P states of heliumlike atoms from helium to neon (both stable and unstable isotopes) have been calculated with accuracy better than 0.1 MHz. The fine structure and hyperfine structure parameters ( CS1,1,CS 1,0,CP1,1, CP1,0,D1, E1,1 and E1,0 ) are calculated using the double-basis-set wavefunctions in Hylleraas coordinates developed by Drake. Hyperfine shifts due to the electric quadrupole interaction, the Breit relativistic, QED and finite nuclear size effects have been included in the calculation. Our results are in good agreement with the recent experimental data.Dept. of Physics. Paper copy at Leddy Library: Theses & Major …
Variational Calculations For General Three-Body Systems., Mark Michael. Cassar
Variational Calculations For General Three-Body Systems., Mark Michael. Cassar
Electronic Theses and Dissertations
A general study of the bound states for the quantum mechanical three-body problem is presented over a broad range of particle masses. The purpose is to identify improved methods for constructing the variational wave functions in terms of the Hylleraas interparticle coordinates r 1, r2, and r12. A new nonlinear parameter is introduced so that distance scales can be set independently for all three coordinates. Significant improvements are found, particularly as the particle masses approach equality and mass polarization effects become large. As a pilot project, high precision variational calculations are carried out for the 1s2 1S ground state of …