Digital Commons Network^™

Investigation Of The Noise Floor Of The Standard Piv Cross-Correlation Algorithm, Kyle L. Jones

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Particle image velocimetry (PIV) is a powerful measurement technique used to acquire instantaneous measurements of entire flow fields at a given instant in time. Quantifying the uncertainty and error in PIV is a critical part of realizing the full potential of PIV as a flow measurement technique.

The noise floor of PIV is the minimum amount of random error that can be achieved for a particular standard cross-correlation (SCC) algorithm. The noise floor of the SCC used by DaVis in correlating image pairs is explored. Two methods for creating image pairs for correlation are compared, namely pseudo image pairs and …

Development Of A Ripple Rejection Controller For Dc Commutated Motors, Spencer M. Atkin

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The requirement of modern systems to be quiet and run smoothly increases production costs. The manufacture and purchase of high quality motors that meet these demands becomes increasingly costly. By using the ever increasing computer power available in micro-controllers, at the same costs, it is possible to use current sensing to develop control adjustments which decrease power ripples caused by the commutators of basic DC commutated motors. These ripples if left unmitigated propagate through to torque ripples which then increase the acoustic noise level present.

Investigation Of Relative Importance Of Some Error Sources In Particle Image Velocimetry, Jeff R. Harris

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Particle image velocimetry (PIV) is an optical technique used to measure fluid velocity. PIV measurements have many sources that create uncertainty in the velocity results. The objective of this report is to investigate some commonly cited uncertainty sources and to show methods than can be used to find the value of the uncertainty sources. These sources are: magnification, calibration, perspective, resolution and the computation scheme. Experiments were conducted to find the impact that sources have on the velocity measurements. Several methods are presented to demonstrate how to measure the uncertainty of error for a PIV experiment. Some error quantities are …

Effect Of Orifice Shape On Synthetic Jet Efficiency, David J. Nani

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

A synthetic jet is formed by periodic oscillation of a fluid through an orifice. The oscillatory motion is driven by diaphragm or other driver. Previous studies have demonstrated that synthetic jet formation and time-averaged cavity pressure are a function of the orifice shape. Traditionally, the performance of the jet is evaluated with varying configurations of fixed driver input voltage or fixed driver displacement. Neither of these measures accurately reflect the efficiency of the actuator. Defining efficiency as "desired output divided by required input," these traditional measures may not account for increase in required driving current or force.

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Streambed Thermal Property Instrument (Spi), James Alwel Dayie

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The purpose of this research, the Streambed thermal Property Instrument (SPI) is to determine the applicability of this instrument for in situ thermal (conductivity and diffusivity) and porous flow (magnitude and direction) measurements. Currently, no such thermal instrument exists for such in situ measurements and the reason for developing this unique instrument, the SPI to fill the technology gap in sediment thermal property measurement devices. Prior to testing the instrument under controlled laboratory conditions to determine its functionality through a series of static and flow tests, the instrument was designed and built. A lab-sized version of an actual river called …

In Situ Method Of Measuring Atmosphere Neutral Winds With A Rigid Falling Sphere, Joshua F. Martineau

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The new falling sphere instruments will measure lower E-region winds and density, which are critical for many of the electrodynamics and plasma physics studies that are carried out as part of the NASA suborbital rocket program. The new falling sphere design will take advantage of modern commercially available electronic components and materials. Of primary importance, it is proposed to fly an in-situ instrument that targets the measurement of neutral wind profiles over the altitude range from 80 to 150 km, with accuracy better than that achieved in previous implementations of the falling sphere technique and those typically obtained with the …

A Validation And Comparison About Vabs-Ide And Vabs-Gui, Teng Hu

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Variational Asymptotic Beam Section (VABS) analysis is a computer code for design and analysis of slender structure such as rotor blades, wind turbine blades, missiles, and rockets more efficiently than a full three-dimensional finite element analysis. VABS enables a rigorously a dimensional reduction of the original three-dimensional nonlinear analysis into a one-dimensional nonlinear beam analysis and a two-dimensional linear cross-sectional analysis. The VABS code has been extensively used in academia and industry for comput- ing the sectional properties and recovering three-dimensional fields of composite slender structures. Recently two graphic user interface, namely VABS-IDE and VABS-GUI, have been developed to automatic …