7,941 Works

Dynamics of Amplitude and Phase in Semiconductor Lasers and Effects of Propagation in Dispersive Optical Fibers

William K. Marshall
The work described in this thesis occupies the region of overlap between the modulation, chirp, and noise properties of semiconductor lasers on one hand and dispersive propagation in optical fiber on the other. It is shown herein that simple relationships exist between the amplitude and phase variations of different kinds and that these relations lead to consequences of dispersive propagation which are different for the noise from semiconductor lasers than for the modulation. A range...

Postdiction and the Effects of Spatial, Temporal, and Feature Compatibility on Sensory Integration

Dylan Rhichard Nieman
The brain continually integrates stimuli over multiple sensory modalities and reconciles often disparate information into a unified, consistent representation of the surrounding environment. This process must be robust to differential neural latencies and imperfect alignments of spatial reference frames between sensory modalities. Numerous studies have examined the perception of multisensory stimuli with the presumption that multisensory integration is categorically different from within-modality integration. We looked at a variety of issues related to the updating of...

Spin-Polarized Quasiparticle Transport in Cuprate Superconductors

Chu-Chen Fu
The effects of spin-polarized quasiparticle transport in superconducting YBa2Cu3O(7-d) (YBCO) epitaxial films are investigated by means of current injection into perovskite ferromagnet-insulator-superconductor (F-I-S) heterostructures. Transport and magnetic properties of these CMR perovskites are first investigated by inducing lattice distortions using lattice mismatching substrates. The half-metallic nature of these perovskites provides an epitaxially grown heterostructure, ideal for injection of spin-polarized current. These effects are compared with the injection of simple quasiparticles into control samples of perovskite...

Groups with only the identity fixing three letters

Gordon Ernest Keller
In this paper, we study finite transitive permutation groups in which only the identity fixes as many as three letters, and in which the subgroup fixing a letter is self normalizing. If G is such a group, the principal results concern the case when G is simple. In this case, H, the subgroup fixing a letter, is a Frobenius group, MQ, with kernel M and complement Q. If |H| is even we show that either...

Highly available distributed storage systems

Lihao Xu
As the need for data explodes with the passage of time and the increase of computing power, data storage becomes more and more important. Distributed storage, as distributed computing before it, is coming of age as a good solution to make systems highly available, i.e., highly scalable, reliable and efficient. The focus of this thesis is how to achieve data reliability and efficiency in distributed storage systems. This thesis consists of two parts. The first...

A Study of Strain Effects in Ni Alloys

Edward Norton Evans
A method for producing uniaxially strained films on an unstrained substrate is described. These films were used to measure the strain sensitivity for γ-phase Ni-Fe and Ni-Co alloys. They were also used to investigate the process of strain relaxation in thin films. The experimental strain sensitivity was found to be roughly half of the strain sensitivity predicted from bulk material properties for all alloys measured. The strain sensitivity was predicted from bulk magnetoelastic constants by...

Fundamental Studies of the Mechanisms and Applications of Field-Induced Droplet Ionization Mass Spectrometry and Electrospray Mass Spectrometry

Ronald L. Grimm
This thesis explores the evaporation and Rayleigh discharge dynamics of highly charged micron-sized droplets and explores new methodologies for extracting ions for mass analysis from neutral droplets using strong electric fields in a technique termed field-induced droplet ionization. A phase Doppler anemometer characterizes individual highly charged droplets moving through a uniform, mild electric field within an ion mobility cell according to size, velocity, and charge. Repeated reversals of the electric field allow multiple characterizations on...

A Study of the T(d,γ)^5He Reaction

Peter Andrew Batay-Csorba
The cross section for the reaction, T(d,γ)5Heg.s., has been measured over the range of deuteron bombarding energies extending from 2 MeV to 12 MeV. A solid ZrT target was employed, and the cross sections were normalized by comparison with the well-known cross sections for the T(d,γ)4Heg.s. reaction. A well shielded, 8" diameter by 5" long NaI(Tl) crystal, 31" from the target, was used to detect the capture γ-radiation. Time-of-flight techniques were employed to suppress cosmic-ray...

Vibration tests of a multistory building

Julio Kuroiwa
Vibration tests were performed on a 9 story reinforced concrete building with basement, in order to investigate its dynamical characteristics, by exciting the building with 2 vibration generators installed on its 9th floor. The natural periods of vibration, the value of the damping, and the mode shapes, in the N-S and E-W directions and in torsion, were determined by measurement. Before the main part of the testing was carried out, some preliminary tests were made...

HOLA: a High-Order Lie Advection of Discrete Differential Forms With Applications in Fluid Dynamics

Alexander George McKenzie
The Lie derivative, and Exterior Calculus in general, is ubiquitous in the elegant geometric interpretation of many dynamical systems. We extend recent trends towards a Discrete Exterior Calculus by introducing a discrete framework for the Lie derivative defined on differential forms, including a WENO based numerical scheme for its implementation. The usefulness of this operator is demonstrated through the advection of scalar and vector valued fields (arbitrary discrete k-forms) in a desirable intrinsic and metric...

Cenozoic nonmarine diatoms from the Great Basin

Kenneth E. Lohman
The wide distribution in the Great Basin area of the Western United States, both geographically and geologically, of the Cenozoic nonmarine diatoms would make them particularly useful for stratigraphic correlation and age determination if their geologic ranges were better known. For this reason, diatoms were collected from some well known vertebrate collecting localities in Nevada, Idaho, and Utah, and the geologic ranges of the individual species established. Of the 353 different species and varieties of...

Spatial, temporal, and chemical aspects of vapor detection using conductive composite chemically sensitive resistors

Shawn Michael Briglin
We have investigated the vapor response properties of chemically sensitive thin film resistors prepared from conductor-insulator composites. A new sensor type was developed from alkylamine-capped gold nanocrystals, and films of this composite, which are composed of nanometer-scale gold cores separated by regions of insulating alkylamine chains, exhibit small reversible resistance increases upon exposure to vapors such as water, acetone, or toluene. However, these films exhibit large irreversible resistance decreases in exposure to vapors possessing the...

Response of simple yielding structures to earthquake excitation

Paul C. Jennings
A method is developed for generating a random process that has the pertinent properties of recorded strong-motion earthquake accelerograms. The model accelerograms are sections of a stationary, Gaussian, random process with a power spectral density found from the average undamped velocity spectrum. Eight pseudo-earthquakes of thirty seconds duration are generated on the digital computer and the velocities, displacements, and velocity spectra calculated. The average velocity spectra of the real and pseudo-earthquakes correspond closely and the...

Investigations in the theory of electromagnetic scattering from expanding dielectric obstacles

Ronald J. Pogorzelski
An equation for the reflection which results when an expanding dielectric slab scatters normally incident plane electromagnetic waves is derived using the invariant imbedding concept. The equation is solved approximately and the character of the solution is investigated. Also, an equation for the radiation transmitted through such a slab is similarly obtained. An alternative formulation of the slab problem is presented which is applicable to the analogous problem in spherical geometry. The form of an...

Balanced flap type supersonic control surfaces

Harry J. Heimer
The purpose of this investigation is to qualitatively explain the flow phenomena which occur on a balanced flap type control surface at supersonic speeds and to find means of calculating the pressure distributions occurring. The popular and generally useful linearized flow theory, and in fact any inviscid theory, cannot be used since viscosity plays a predominant part in the determination of the flow. It is shown that the flow often involves shock induced separation and...

Part I: Rates of paramagnetic pulse reactions by nuclear magnetic resonance. Part II: The electron paramagnetic resonance spectrum of gas phase nitrogen-dioxide (composed of nitogen-14, oxygen-16) and its pressure dependence

Stuart Brooke Berger
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Part I of this thesis concerns the classically derived theory of the effect on the nuclear magnetic resonance line width and shape of a species which has a nucleus under investigation and is involved in an electron exchange reaction. The result is that the pseudo-first order reaction rate constant is added, under certain conditions, directly onto...

Ion implantation in epitaxial GexSi1-x on Si(100)

Yu-Chun Donald Lie
The question of whether one can effectively dope or process epitaxial Si(100)/GeSi heterostructures by ion implantation is experimentally investigated. Results that cover several different ion species (Si, P, and As), doses (1.0x10[superscript 13]/cm[superscript 2] to 1.5x10[superscript 15]/cm [superscript 2]), implantation temperatures (RT to 150°C), as well as annealing techniques (steady-state and rapid thermal annealing) are included in this thesis. Implantation-induced damage and strain and their annealing behavior for both strained and relaxed GeSi are measured...

Luminescence properties of electron-hole-droplets in pure and doped germanium

Martin Chen
This work contains 4 topics dealing with the properties of the luminescence from Ge. The temperature, pump-power and time dependences of the photoluminescence spectra of Li-, As-, Ga-, and Sb-doped Ge crystals were studied. For impurity concentrations less than about 1015cm-3, emissions due to electron-hole droplets can clearly be identified. For impurity concentrations on the order of 1016cm-3, the broad lines in the spectra, which have previously been attributed to the emission from the electron-hole-droplet,...

An investigation of the effect of the muzzle on the motion of the projectile in a recoilless gun

Frank Arthur Woodward
Expressions for the position and velocity of a projectile at any time in a recoilless gun are derived. The one dimensional wave equation is assumed to be valid in describing the motion of the gas. The muzzle velocity of the projectile is calculated, and compared with that obtained for the case in which no waves are reflected back from the muzzle. It is shown that the effect of the reflected waves is to increase the...

Multiscale numerical methods for the singularly perturbed convection-diffusion equation

Peter J. Park
We develop efficient and robust numerical methods in the finite element framework for numerical solutions of the singularly perturbed convection-diffusion equation and of a degenerate elliptic equation. The standard methods for purely elliptic or hyperbolic problems perform poorly when there are sharp boundary and internal layers in the solution caused by the dominant convective effect. We offer a new approach in which we design the finite element basis functions that capture the local behavior correctly....

Studies on the role of histones in the structure and function of chromatin

John Edward Smart
Studies on the dissociation of histones from chromatin by increasing concentrations of sodium deoxycholate (DOC) have shown that histrone II is removed at lowest concentrations of DOC, while slightly higher concentrations remove histones III and IV. Still higher concentrations remove histone I. The complete separation of chromatin and 14C-DOC by sucrose sedimentation indicated that the binding of DOC to chromatin is readily and completely reversible. The dissociation of histones from chromatin by increasing concentrations of...

Damage mechanisms in shock wave lithotripsy (SWL)

Murtuza Lokhandwalla
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Shock wave lithotripsy is a 'non-invasive' therapy for treating kidney stones. Focused shock waves fragment stones to a size that can be passed naturally. There is, however, considerable tissue injury associated with this treatment, and the mechanisms of stone fragmentation and tissue injury are not well understood. This work investigates potential tissue damage mechanisms, with an...

The double transitivity of a class of permutation groups

Ronald David Bercov
In this thesis primitive finite permutation groups G with regular abelian subgroup H are studied. It is shown that if, for an odd prime p, H has a Sylow p-subgroup which is the direct product of two cyclic groups of different order, then G is doubly transitive.

Utilization of Silicides for VLSI-Contacts with Aluminum and Thermal Oxidation

Meir Bartur
The potential role of silicides in VLSI (very large scale integration) Si technology is described. A survey of trends and requirements exposes two difficult technological issues as the device dimensions shrink: contacts to the individual devices and interconnections between devices or functional blocks on the Si chip. For both, silicides play an important role. The contact between the Si that contains the device and the top Al layer (Al is the preferred metal for metallization)...

The plate problem for a cantilever sector of uniform thickness

Max L. Williams
As one approach to the problem of analyzing missile wings of approximately delta configuration for stress and deflection characteristics, a uniformly thin plate of sector planform clamped along one radial edge has been considered. It is shown that an infinite set of deflection functions, resulting from a product solution to the double Laplacian, may be generated, but practical utility is impeded because the functions are non-orthogonal. It is believed that should the importance of the...

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