2,172 Works

Lunar University Network for Astrophysics Research: Comprehensive Report to The NASA Lunar Science Institute. March 1, 2012

Jack Burns & Joseph Lazio
The Lunar University Network for Astrophysics Research (LUNAR) is a team of researchers and students at leading universities, NASA centers, and federal research laboratories undertaking investigations aimed at using the Moon as a platform for space science. LUNAR research includes Lunar Interior Physics & Gravitation using Lunar Laser Ranging (LLR), Low Frequency Cosmology and Astrophysics (LFCA), Planetary Science and the Lunar Ionosphere, Radio Heliophysics, and Exploration Science. The LUNAR team is exploring technologies that are...

Linear and Non-linear Interactions in a Rough-Wall Turbulent Boundary Layer

Jonathan P. Morgan
This thesis explores the linear and non-linear interactions which take place in a rough-wall turbulent boundary through experiments and modeling. In order to derive physics-based models for the relation between roughness geometry and flow physics, two very simple periodic roughnesses were 3D printed and placed in a boundary layer wind tunnel for separate experiments. Hot-wire measurements were taken at a grid of points within a single period of the roughness in order to map the...

Experimental, Numerical and Analytical Studies of the MHD-driven plasma jet, instabilities and waves

Xiang Zhai
This thesis describes a series of experimental, numerical, and analytical studies involving the Caltech magnetohydrodynamically (MHD)-driven plasma jet experiment. The plasma jet is created via a capacitor discharge that powers a magnetized coaxial planar electrodes system. The jet is collimated and accelerated by the MHD forces. We present three-dimensional ideal MHD finite-volume simulations of the plasma jet experiment using an astrophysical magnetic tower as the baseline model. A compact magnetic energy/helicity injection is exploited in...

Glacial Ocean Dynamics: Insight from Deep-Sea Coral Reconstructions and A Time-Dependent Dynamical Box Model

Sophia Katharine Vizza Hines
Glacial-interglacial cycles, occurring at a period of approximately 100,000 years, have dominated Earth's climate over the past 800,000 years. These cycles involve major changes in land ice, global sea level, ocean circulation, and the carbon cycle. While it is generally agreed that the ultimate driver of global climate is changes in insolation, glacial cycles do not look like insolation forcing. Notably, there is a highly non-linear warming response at 100,000 years to a relatively small...

Problems Relating to the Use of Sheet Metal in Airplane Construction

Ernest Edwin Sechler
Sheet metal as used in present airplane construction may have two separate and distinct functions. The first of these is merely to supplant fabric or other covering material on the airplane. The structure of the airplane is not altered and the load is completely taken by the framework. The added strength and durability of this type of covering is usually connected with an increase in weight which makes the practice uneconomical. This use of metal...

Reactions of Small Molecules Facilitated by Metal-Acceptor Interactions

Daniel Leif Migdow Suess
The role of metal-acceptor interactions arising from M–BR3 and M–PR3 bonding is discussed with respect to reactions between first-row transition metals and N2, H2, and CO. Thermally robust, S = 1/2 (TPB)Co(H2) and (TPB)Co(N2) complexes (TPB = tris(2- (diisopropylphosphino)phenyl)borane) are described and the energetics of N2 and H2 binding are measured. The H2 and N2 ligands are bound more weakly in the (TPB)Co complexes than in related (SiP3)M(L) complexes (SiP3 = tris(2- (diisopropylphosphino)phenyl)silyl). Comparisons within...

Boundary-layer transition on a slender cone in hypervelocity flow with real gas effects

Joseph Stephen Jewell
The laminar to turbulent transition process in boundary layer flows in thermochemical nonequilibrium at high enthalpy is measured and characterized. Experiments are performed in the T5 Hypervelocity Reflected Shock Tunnel at Caltech, using a 1 m length 5-degree half angle axisymmetric cone instrumented with 80 fast-response annular thermocouples, complemented by boundary layer stability computations using the STABL software suite. A new mixing tank is added to the shock tube fill apparatus for premixed freestream gas...

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Computer Science Technical Reports

Insights on the Formation and Fate of Organic Nitrates in the Atmosphere from Field and Laboratory Observations

Alexander Pai-Chung Teng
Alkenes are oxidized rapidly in the atmosphere by addition of OH and subsequently O2, leading to the formation of peroxy radicals. These peroxy radicals react with NO to form organic nitrates through a minor radical-terminating branching pathway. Over large regions of the continental boundary layer, the formation of organic nitrates control tropospheric ozone and the lifetime of NOx. Laboratory investigations described herein show that the yield of nitrates through this pathway is larger than previously...

Stratigraphy and Correlation of the Marine Jurassic Deposits of Central Oregon

Ralph Leonard Lupher
Marine Jurassic rocks occupy an area of more than 200 square miles in the pre-Tertiary area of Central Oregon. Eight formations are recognized in a series that ranges in age from the middle Lias to the Callovian of the upper Jura. The faunas are grouped into four chronologic divisions which are not coincident with the stratigraphi divisions. The two sets of divisions may be compared in the following manner: [See Abstract in PDF for more...

Search for SUSY with Delayed Photons at the Compact Muon Solenoid

Gillian Baron Kopp
The Compact Muon Solenoid (CMS) experiment records data from proton-proton (pp) and heavy ion (Pb-Pb and Pb-p) collisions at the Large Hadron Collider (LHC) to search for physics beyond the Standard Model, test theories of supersymmetry (SUSY), and measure properties of known particles with higher precision. In 2025, the LHC will be upgraded to the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10. This will increase the number...

Theory of Magnetic Methods of Applied Geophysics with an Application to the San Andreas Fault

Joshua Lawrence Soske
The attempts of geological and mining engineers to decipher the structure of the outermost formations of the earth's crust have led to many comprehensive studies, which now stand as monuments to their efforts. Their studies, in general, are confined almost exclusively to systematic collection, description, and analysis of facts which they were able to obtain by immediate observation at accessible points on and near the surface of the earth. These observations have many times been...

A Unified Strategy to Ent-Kauranoid Natural Products: Total Syntheses of (-)-Maoecrystal Z, (-)-Trichorabdal A, and (-)-Longikaurin E

John Thomas Schafer Yeoman
The diterpenoid constituents of the Isodon plants have attracted reasearchers interested in both their chemical structures and biological properties for more than a half-century. In recent years, the isolations of new members displaying previously unprecedented ring systems and highly selective biological properties have piqued interest from the synthetic community in this class of natural products. Reported herein is the first total synthesis of such a recently isolated diterpenoid, (–)-maoecrystal Z. The principal transformations implemented in...

Slender-Body Hypervelocity Boundary-Layer Instability

Nicholaus J. Parziale
With novel application of optical techniques, the slender-body hypervelocity boundary-layer instability is characterized in the previously unexplored regime where thermo-chemical effects are important. Narrowband disturbances (500-3000~kHz) are measured in boundary layers with edge velocities of up to 5~km/s at two points along the generator of a 5 degree half angle cone. Experimental amplification factor spectra are presented. Linear stability and PSE analysis is performed, with fair prediction of the frequency content of the disturbances; however,...

Terahertz and Microwave Spectroscopy of Liquids and Hydrogen-Bonded Clusters

Ian Alan Finneran
The microwave (MW, 0.3-100 GHz) and terahertz (THz, 0.1-10 THz) regions of the electromagnetic spectrum are replete with a rich set of molecular motions, including soft inter- and intramolecular vibrations, torsions, and rotations. At room temperature these motions are well populated, and play an active role in condensed-phase chemistry on Earth. This work details the development of one MW and two THz spectrometers along with their application to the study of liquids and hydrogen-bonded clusters....

The Absorption Coefficient of Hard Gamma-Rays

Chung-Yao Chao
The relation between the frequency of hard radiations and the absorption co-efficient is not experimentally well established at the present time. In the following work the absorption coefficient of γ-rays of ThC" is carefully investigated owing to their homogeneity. As a result, the observed absorption coefficient of light elements is found to agree fairly well with the theoretical formula of Klein and Nishina. Running from low to high atomic numbers, the absorption per electron is,...

Membrane Potential Dynamics of Hippocampal Neurons During Ripples in Awake Mice

Bradley Kline Hulse
During periods of slow wave sleep and quiet wakefulness, the hippocampal formation generates spontaneous population bursts that are organized as a high-frequency “ripple” oscillation. The neurons that participate in these bursts often replay previously experienced activity patterns encoded during alert behavior, and interfering with ripple generation produces deficits in learning and memory tasks. For these reasons, ripples play a prominent role in theories of memory consolidation and retrieval. While spiking during ripples has been extensively...

Flashover of Insulation in Homogenous Electric Fields

George K. Surrapas Diamos & William Abbett Lewis
No Abstract.

Electromechanical Properties of 3D Multifunctional Nano-Architected Materials

Max Louis Lifson
In this thesis, we explore the fabrication and characterization of 3D architected multifunctional materials in three different categories: varied density for tailored mechanical response, stiff ultra low-k dielectric materials, and direct laser writing of piezoelectric structures at the micron scale. The density of an architected material plays a large role in determining its effective Young’s modulus, strength, and deformation behavior. The first section of this work explores the effect of incorporating two density regions into...

On Ultrafast Time-Domain TeraHertz Spectroscopy in the Condensed Phase: Linear Spectroscopic Measurements of Hydrogen-Bond Dynamics of Astrochemical Ice Analogs and Nonlinear TeraHertz Kerr Effect Measurements of Vibrational Quantum Beats

Marco Alberto Allodi
Much of the chemistry that affects life on planet Earth occurs in the condensed phase. The TeraHertz (THz) or far-infrared (far-IR) region of the electromagnetic spectrum (from 0.1 THz to 10 THz, 3 cm-1 to 300 cm-1, or 3000 μm to 30 μm) has been shown to provide unique possibilities in the study of condensed-phase processes. The goal of this work is to expand the possibilities available in the THz region and undertake new investigations...

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