4,827 Works

Wind tunnel investigation of the aerodynamic characteristics of high lift devices on supersonic wings at low subsonic speed

J. E. Densmore
An investigation was made to determine the effect of various high lift devices on a highly sweptforward wing with a leading edge sweep angle of 55 degrees and on a straight wing, both wings having an aspect ratio of 1.72 and the same span. Experimental tests were made in the Cal Tech - Merrill low speed wind tunnel at Pasadena City College on both types of wing with and without fuselage. High lift devices investigated...

On the flow of vapor between liquid surfaces

Warren Edward Mathews
An analysis of the one-dimensional flow of vapor between parallel liquid surfaces of identical composition but different temperatures is presented. The low velocity steady flow analysis reported previously by Plesset is extended to steady flows in which the Mach number approaches unity, and to low velocity flows in which the liquid surface spacing and temperatures are allowed to vary slowly with time. More important among the new results obtained are 1) an exact solution in...

An experimental investigation of the transfer of heat from small wires to a viscous compressible fluid

Richard J Magnus
A steam tunnel, suitable for making experimental measurements of the heat transfer from fine wires to a viscous compressible fluid, was developed and constructed. Measurements of Nusselt numbers and recovery temperatures were carried out using small-diameter (0.00038 to 0.00254 cm.) tungsten wires in steam flow with Reynolds numbers ranging from about 1 to 12 and with nominal Mach numbers of 0.5 to 1.7. Considerable difference was found between the Nusselt numbers for wires in subsonic...

Neutral pion photoproduction from deuterium in the energy range 1/2 to 1 Bev

Harry H. Bingham
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Gamma rays from the decay of neutral pions photoproduced in the bremsstrahlung beam of the Caltech synchrotron from high density deuterium and hydrogen gas have been observed with a Thallium Chloride crystal gamma ray spectrometer. Integral gamma ray yields and gamma ray energy spectra have been obtained for several bremsstrahlung endpoint energies from 0.6 to 1.08...

Some approximate solutions of dynamic problems in the linear theory of thin elastic shells

Michael Philip Mortell
Some aspects of wave propagation in thin elastic shells are considered. The governing equations are derived by a method which makes their relationship to the exact equations of linear elasticity quite clear. Finite wave propagation speeds are ensured by the inclusion of the appropriate physical effects. The problem of a constant pressure front moving with constant velocity along a semi-infinite circular cylindrical shell is studied. The behavior of the solution immediately under the leading wave...

A Proximity Formulation of Nuclear Dynamics

Gregory John Ball
The nuclear potential, the transfer-induced dissipation, and the mass diffusion coefficient in heavy-ion collisions are investigated in a proximity formulation. An energy-dependent nuclear potential is calculated in the frozen wave function approximation using two slabs of symmetric nuclear matter, each described by Hartree-Fock single-particle wave functions. Corrections to the inertia parameter are also evaluated from this potential. The flux entering the window formula for the friction between two heavy ions is calculated in a simple...

GW190425: Strain and Data Quality Data Set observed by LIGO and Virgo

LIGO Scientific Collaboration and VIRGO Collaboration

The evaporation rate of liquid droplets in a hot gas

Frederic William Hartwig
Calculations have been carried out in order to determine the rate of evaporation of a liquid droplet surrounded by hot gases. The present study represents an extension of earlier work by Penner on evaporation rates for isothermal droplets. Thus, allowance was made for temperature gradients withing the droplet (a) by considering a droplet composed of an isothermal core and an isothermal shell and (b) by utilizing the actual termperature profile in the droplet as established...

General Methods for Analyzing Higgs Potentials

Jai Sam Kim
This thesis is based on several papers published by the author and some more work to be published. We explain the technical problem of minimizing Higgs potentials using group theoretical concepts. Three mathematical results which belong to distinct areas are used to analyze the Higgs potential in an abstract way. The problem reduces to one of finding "contours" of directional minima and thus our method is geometrical. It is explained in detail and demonstrated for...

Lagrangian averaging, nonlinear waves, and shock capturing

Harish Subrahmanya Bhat
In this thesis, we explore various models for the flow of a compressible fluid as well as model equations for shock formation, one of the main features of compressible fluid flows. We begin by reviewing the variational structure of compressible fluid mechanics. We derive the barotropic compressible Euler equations from a variational principle in both material and spatial frames. Writing the resulting equations of motion requires certain Lie-algebraic calculations that we carry out in detail...

Column creep of 75S-T6 aluminum alloy

Richard Gaibler
This thesis is a report of the results of the column phase of a three part experimental investigation of short time creep properties of light metal alloys under conditions of high loadings and elevated temperatures. The other parts of the investigation were concerned with creep properties of these alloys in tension and in compression. The former is described by R. J. Kauffman; the latter by R. C. Thatcher (Refs. 11 and 12). Creep characteristics of...

The exchange excitation of helium and the hydrogen molecule by low energy electrons

David Chapman Cartwright
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The theory of rearrangement collisions involving composite particles is reviewed and the "post", "prior" discrepancy discussed. Two recent improvements to the Born-Oppenheimer approximation, the Ochkur (O), and Ochkur-Rudge (OR) approximations are reviewed. These approximations are then used to calculate the total cross section for the electronic excitation, of molecular hydrogen by low energy electrons. Excitations from...

Long-term modeling of regional ozone concentrations and control strategies

Darrell Alan Winner
The capability to accurately model the long-term frequency of occurrence of high and low ozone concentrations in the urban and regional atmosphere is developed. A full year of hourly ozone concentration predictions is generated throughout Southern California using a photochemical airshed model driven by automated assimilation of routine meteorological observations. Statistical measures of airshed model performance for the full year are comparable to results achieved by episodic models for 2-3 days of simulation that are...

Structural Analysis of Imperfect Three-Legged Truss Columns for Large Space Structures Applications

Dov Elyada
Three-legged truss columns are basic structural components of many envisioned large outer-space structures. They constitute three longerons ('legs') forming, in the column cross-section, the vertices of an equiliateral triangle. Their longerons are held together by uniformly spaced battens while a shear web, usually made of diagonals, restrains shear deformation. This work deals with configurations characterized by having relatively stiff battens, longerons which are pinned to the battens and prestressed string diagonals. Considered are only simply-supported...

Electrochemistry of Polymer-Metal Complexes

Paul Vincent Neilson
Polymeric ligands, Polyethylenimine (PEI) and Chitosan, were studied for possible applications in the modification of electrode surfaces in relation to the three main goals: 1. metal ion scavenging 2. to find a system which catalyzes O2 reduction 3. understanding of electron transfer in polymer-metal films.

Shock wave propagation in periodically layered composites

Shiming Zhuang
Mathematically, a shock wave is treated as a discontinuity in a medium. In reality, however, a shock wave is always structured, i.e., its front takes a finite time to rise from an initial material state to the final shocked state. The structuring of a shock front is due to the competition between the nonlinearity of material behavior and the dissipation processes occurring during the wave propagation. There are many mechanisms which may be responsible for...

Energetic Oxygen and Sulfur Ions in the Jovian Magnetosphere

Neil Gehrels
Observations of 1 to 20 MeV/nuc oxygen, sodium, and sulfur ions in the Jovian magnetosphere are reported. Measurements made by the Cosmic Ray Subsystem on Voyager 1 and 2 are used to calculate abundances and energy spectra in the region from 5 to 20 Jovian radii (RJ). The phase space density of the oxygen ions calculated from the spectra has a positive radial gradient between 6 and 17 RJ, indicating an inward diffusive flow. The...

Deterministic annealing, clustering, and optimization

Kenneth Rose
This work introduces the concept of deterministic annealing (DA) as a useful approach to clustering and other related optimization problems. It is strongly motivated by analogies to statistical physics, but is formally derived within information theory and probability theory. This approach enables escaping local optima that plague traditional techniques, without the extremely slow schedules typically required by stochastic methods. The clustering solutions obtained by DA are totally independent of the choice of initial configuration. A...

Growth and characterization of Y-BA-CU-O high-Tc superconductor thin films

Jorge A. Kittl
Two types of growth processes of Y-Ba-Cu-O thin films were investigated: three step processes involving post deposition high temperature anneals, and in situ growth processes. Films were deposited by sequential ion beam sputtering from elemental Y, Ba and Cu targets, and characterized by x-ray diffraction, transmission and scanning electron microscopy, energy dispersive x-ray analysis, Rutherford backscattering spectrometry, and low temperature resistivity measurements. In the three step process, multilayers of ~60 Å periodicity were deposited on...

Correlation of existing design information on sandwich construction

Douglas C. Ogilvie
The problem considered is one of survey and correlation of existing design information on sandwich construction. The subject matter deals with the types of sandwiches, advantages, buckling and stress analysis, published test data, design methods, core materials, weight comparisons, current applications and the manufacture, repair and inspection of sandwich construction. Suggestions for extensions needed are given and where obvious improvements in analysis could be seen, these modified methods were suggested. Suggested further work - Every...

Retinomorphic vision systems : reverse engineering the vertebrate retina

Kwabena Adu Boahen
This thesis seeks to explain how the retina satisfies both top-down constraints (functional) and the bottom-up constraints (structural) by analyzing simple physical models of the retina and mimicking its structure and function in silicon. In particular, I examine spatiotemporal filtering in the outer plexiform layer of the vertebrate retina, and show how outer retina processing is augmented by further processing in the inner plexiform layer, creating an efficient implementation that encodes moving stimuli efficiently over...

Experimental investigation of detached shock waves on a 70 degree cone at various angles of attack

Leo F. Frick
An experimental investigation was made to determine the variation of shock shape and extent of subsonic region behind the shock wave with angle of attack for a 70° cone at various Mach numbers. The main interest was centered on those Mach numbers which produced detached shock waves or for which the possibility of detachment at angle of attack existed. The tests were conducted in the GALCIT 2.5" Supersonic Wind Tunnel at angles of attack of...

Effects of controlled three-dimensional perturbations on boundary layer transition

Steven Philip Schneider
The laminar-turbulent transition in a flat plate boundary layer was studied experimentally using a spanwise array of computer-controlled surface heating elements. The elements were used to introduce disturbances at a point just downstream of the critical Reynolds number. When sinusoidal heating at an unstable frequency is carried out, instability waves develop and grow as they travel downstream. Measurements were made using flush-mounted hot-film wall shear sensors, and the later stages of transition were visualized using...

The hydrodynamics of spherical cavities in the neighborhood of a rigid plane

Joseph Matthew Green
The velocity potential in a perfect fluid is found for a sphere which is translating in a direction normal to a rigid plane and which is simultaneously undergoing a change in its radius. The solution of the problem is conveniently pursued in the bispherical coordinate system. The kinetic energy of the fluid is determined. The dynamics of the motion of the translating sphere of variable radius is then described in terms of a Lagrangian which...

Studies on the L-Amino Acid Oxidase of Neurospora Crassa

Philip Standish Thayer
The L-amino acid oxidase of Neurospora is a gen­eral amino acid oxidase attacking a wide range of L-amino acids at different rates. Activity of the enzyme is de­pendent on substrate concentration, oxygen tension and pH. Different amino acids show different pH optima. Activity is significantly reduced by excess substrate, and competition is exhibited between mixed substrates. L-oxidase production by mycelium is increased 4 to 10 fold by biotin limitation. This effect is not produced by:...

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