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Full-Text Articles in Physical Sciences and Mathematics

Measurement System For High Pressure Characterizations Of Materials, Matthew K. Jacobsen Dec 2010

Measurement System For High Pressure Characterizations Of Materials, Matthew K. Jacobsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Thermoelectric materials have long been investigated for possible use as power sources. This application was recently put to use in the Voyager space program, powering the deep space probes. Despite the usefulness of these materials, the use of pressure to investigate the material properties has only recently become interesting. As such, the work in this document was to developing a system for concurrently measuring the necessary properties. This system is capable of measuring the electrical resistivity, thermal conductivity, and Seebeck coefficient in the pressure range from 0 - 10 GPa. The results for zinc, almandine garnet, and nickel are presented …


Nonlinear Observers For Human-In-The-Loop Control Systems, Samuel Kitchen Mckinley Jul 2010

Nonlinear Observers For Human-In-The-Loop Control Systems, Samuel Kitchen Mckinley

Master's Theses - Daytona Beach

The development of models for a human-in-the-loop with hardware is an area of ongoing research. The ability to simulate a human-in-the-loop with hardware provides a platform for better understanding the dynamics of human and machine cognition. A human-in-the-loop model provides information that can be used to design more efficient human interfaces and smarter autonomous assistant controllers. This can make a complex task such as flying an aircraft safer and more accessible. This thesis explores different possibilities for human operator models to be modeled in the loop with a vehicle. A human is modeled as a linear state feedback controller in …


Construction And Enhancement Of Stereo Vacuum Tube Amplifier With Precision Machined Enclosure, Nikolaus (Nik) Glazar May 2010

Construction And Enhancement Of Stereo Vacuum Tube Amplifier With Precision Machined Enclosure, Nikolaus (Nik) Glazar

Physics

The purpose of this project was to build a high fidelity tube amplifier from a kit, and machine a beautiful enclosure to house the electronics. Improvements were made to the circuit, and the amplifier was then tested for audio performance.


An Investigation Of Gas Bubble Generation And Measurement In Water And Mercury, Stuart A Walker May 2010

An Investigation Of Gas Bubble Generation And Measurement In Water And Mercury, Stuart A Walker

Masters Theses

The pressure increase attributed to the energy deposition in the liquid metal target of the Spallation Neutron Source results in cavitation and pitting erosion of the target pressure boundary. Introducing compressibility in the form of small gas bubbles will extend the lifetime of the target vessel. The pressure rise caused by the beam energy deposition occurs in one microsecond, which encourages use of bubbles of radius less than 20 microns, such that the bubble response to pressure change is adequately fast. Gas volume fraction near 0.5% is sufficient to accommodate the mercury volumetric expansion and reduce the pressure rise. Bubble …


Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller Mar 2010

Rubidium Recycling In A High Intensity Short Duration Pulsed Alkali Laser, Wooddy S. Miller

Theses and Dissertations

Laser induced fluorescence was used to study how pump pulse duration and alkali recycle time effects maximum power output in a Diode Pumped Alkali Laser (DPAL) system. A high intensity short pulsed pump source was used to excited rubidium atoms inside a DPAL-type laser. The maximum output power of the laser showed a strong dependence upon the temporal width of the pump pulse in addition to the input pump intensity. A linear relationship was observed between the maximum output power and the pulse width due to the effective lifetime of the excited state, defined as the time it takes for …


Improving Low Order, Linear, Positive Spatial Quadratures For The Partial Current Neutron Transport Method, John M. Snyder Mar 2010

Improving Low Order, Linear, Positive Spatial Quadratures For The Partial Current Neutron Transport Method, John M. Snyder

Theses and Dissertations

AFIT researchers have developed a new approach to solving Discrete Ordinates equations, which approximate the linear Boltzmann Transport Equation (BTE). The usual approach is von Neumann iteration on the scattering source, which requires repeated sweeps through the spatial-angular grid. Acceptable convergence requires complicated and expensive acceleration schemes. The new approach, Partial-Current Transport (PCT) with Adaptive Distribution Iteration, eliminates scattering source iteration through matrix inversions and a reduced-size global linear algebra problem. It creates the needed matrices directly from the standard spatial quadratures used in the sweeping. Positivity, linearity, and (higher-than-first-order) accuracy are the key desirable qualities with all Discrete Ordinates …