Acoustics, Dynamics, and Controls Commons^™

Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer

Master's Theses

The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration …

Automating The Fret Slotting Process Using A Plc Controlled 1.5 Axis Mill, James Stratton

Purdue Polytechnic Masters Theses

Stratton, James A. M.S., Purdue University, August 2011. Automating the Fret Slotting Process Using a PLC Controlled 1.5 Axis CNC Mill. Major Professor: Richard Mark French.

Can automation assist small job shops and hobbyists in the production of stringed instruments? This research set out to answer the question using a quantitative approach to determine if an economical CNC machine could be produced in such a fashion as to seamlessly join the workshop as an affordable, yet precise instrument to aid in the production of stringed instruments. The key was to incorporate common industrial automation equipment into the operation of the …

Perfectly Matched Layer Absorbing Boundary Conditions For The Discrete Velocity Boltzmann-Bgk Equation, Elena Craig

Mathematics & Statistics Theses & Dissertations

Perfectly Matched Layer (PML) absorbing boundary conditions were first proposed by Berenger in 1994 for the Maxwell's equations of electromagnetics. Since Hu first applied the method to Euler's equations in 1996, progress made in the application of PML to Computational Aeroacoustics (CAA) includes linearized Euler equations with non-uniform mean flow, non-linear Euler equations, flows with an arbitrary mean flow direction, and non-linear clavier-Stokes equations. Although Boltzmann-BGK methods have appeared in the literature and have been shown capable of simulating aeroacoustics phenomena, very little has been done to develop absorbing boundary conditions for these methods. The purpose of this work was …

Quantifying Multiple Types Of Damping Acting On Bronze-Wound Guitar Strings, Jonathan Christian

Purdue Polytechnic Masters Theses

The goal of this study was to quantify the contributions of multiple damping types acting on guitar strings for each mode over a wide frequency range so that design variables could be identified to one day create frequency based damping in guitar strings. Structural dynamic testing was used to obtain the time-response of a vibrating string in open air and in a vacuum. From this signal, each harmonic was filtered and the decay envelope was curve-fitted with a function that was a linear summation of decay functions. From the curve-fits, the damping coefficients for aerodynamic, friction, and material damping were …

Applied Control Strategies At A Cogeneration Plant, Joseph William Burns

Master's Theses

The purpose of this paper is to demonstrate the effectiveness of “classical strategies for dynamic control” on authentic cogeneration processes. These strategies are applied to several processes at the University of Connecticut’s cogeneration plant. Case studies of their applications are presented in this paper. Strategies that are applied include the following:

1) The classical SISO feedback structure

2) The First Order Plus Dead Time (FOPDT) process model

3) The Internal Model Control (IMC) correlations for PI controller tuning

4) Static feed forward with feedback trim

5) Cascade Control

Multiple Motors With Single Controller, Jason Eugene Barbeiro, Benjamin Erik Johnson, Abraham Garza

Mechanical Engineering

No abstract provided.

Development Of A Cubesat Instrument For Microgravity Particle Damper Performance Analysis, John Trevor Abel

Master's Theses

Spacecraft pointing accuracy and structural longevity requirements often necessitate auxiliary vibration dissipation mechanisms.  However, temperature sensitivity and material degradation limit the effectiveness of traditional damping techniques in space.  Robust particle damping technology offers a potential solution, driving the need for microgravity characterization.   A 1U cubesat satellite presents a low cost, low risk platform for the acquisition of data needed for this evaluation, but severely restricts available mass, volume, power and bandwidth resources.  This paper details the development of an instrument subject to these constraints that is capable of capturing high resolution frequency response measurements of highly nonlinear particle damper dynamics.

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …

Control System For Mass Spectrometer, Jian Xu

Purdue Polytechnic Masters Theses

Mass spectrometry (MS) is a very popular analytical methodology that measures the mass of ions using a mass spectrometer. It is widely used for determining masses of chemicals, the elemental composition of a sample and molecule structure. The process of mass spectrometry normally consists of ionizing chemical compounds to ions and measuring their ratios of mass to charge for analysis.

MS instruments consist of three modules: Ionization, Analysis and detection. A LabVIEW system was developed to control the three modules of a mass spectrometer, giving the required signals in a right sequence. Experiments can be carried out by using the …

Airplane Landing Flare-The Last 5 Seconds, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Effects Of Inlet Conditions On Diffuser Outlet Performance, Zaccary A. Poots

UNLV Theses, Dissertations, Professional Papers, and Capstones

Building air distribution terminal system designers and system installers require accurate quantitative information on the performance of the installed system to achieve optimum efficiency and levels of human comfort. This requires field installation adjustment values from published ideal pressure loss, air distribution and sound generation installation performance. This study documents the air output performance of different installation configurations of six types of ceiling diffusers and compares the results to performance when installed according to ANSI/ASHRAE Standard 70-2006. A diffuser inlet supply plenum was designed for optimum flow and used to acquire a baseline set of data covering the six types …

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …

Robust Region Tracking In Multi-Agent Systems Utilizing Sliding Mode Control: Theory And Applications, Mark Bacon

Master's Theses

This thesis presents a methodology to bring controlled agents within a moving region despite agent interaction dynamics, uncertain forces and parameter variation. The logic is derived from traditional Sliding Mode Control theory with an expanded boundary layer which allows position deviation from the region center to specified bounds. As an example of the utility of this control, multiple methods of herding (controlling passive agents by appropriate positioning of controlled agents) are presented.

Lv-11-C031: Measured Levels Of Hospital Noise Before, During, And After Renovation Of A Hospital Wing, And A Survey Of Resulting Patient Perception, Cassandra H. Wiese, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

Acoustic conditions in hospitals can negatively influence a patient’s physical and psychological health. This paperreports on noise levels measured before, during, and after renovation of a hospital wing in an Omaha, Nebraska, facility thatregularly receives unsatisfactory noise scores on patient satisfaction surveys. Sound pressure levels were logged every 10seconds over four-day periods in three different locations: at the nurses' station, in the hallway, and in a nearby patient’sroom. The resulting data have been analyzed in terms of A-weighted equivalent sound levels (LAeq) as well as variousexceedance levels (Ln). Results indicate that sound levels did not change much due to the …

Effects Of A Heated Turbulent Boundary Layer On Surface Pressure Fluctuations, David William Rich

Electronic Theses and Dissertations

Recent work has shown that spatial correlation of surface pressure fluctuations in a fully turbulent atmospheric boundary layer (ABL) can give information about the velocity field and turbulence. This is of particular importance to the future of wind energy to predict the incoming velocity flow field of wind turbines so as to actively control them for peak operating efficiency and damage reduction. All of the environmental effects on the surface pressure fluctuations need to be fully understood before a suitable flow prediction algorithm can be constructed. One such environmental effect which has not been previously studied is the effect of …

Quantification Of An Ultrasound Test Apparatus And Its Potential Use To Control Nuisance Species In Commercial Aquaculture Settings, Bradley T. Goodwiller

Electronic Theses and Dissertations

As one step in the investigation of using acoustics to improve aquaculture production, work was pursued on the possible use of ultrasound to control the Bolbophorus trematode in commercial catfish ponds. The trematode population can be controlled by eliminating the host ram's horn snail via exposure to high amplitude ultrasound. Initial laboratory tests indicated that a commercially available sonicator (operating at 20 kHz) is capable of killing individual snails in fish tanks. More thorough testing indicated efficiency rates of approximately 35% on batches of 10 snails. In addition to the snails killed immediately, there was evidence that the sonication technique …

Locating And Extracting Acoustic And Neural Signals, Na Zhu

Wayne State University Dissertations

This dissertation presents innovate methodologies for locating, extracting, and separating multiple incoherent sound sources in three-dimensional (3D) space; and applications of the time reversal (TR) algorithm to pinpoint the hyper active neural activities inside the brain auditory structure that are correlated to the tinnitus pathology. Specifically, an acoustic modeling based method is developed for locating arbitrary and incoherent sound sources in 3D space in real time by using a minimal number of microphones, and the Point Source Separation (PSS) method is developed for extracting target signals from directly measured mixed signals. Combining these two approaches leads to a novel technology …

An Advanced Controller For A Semi-Active Wheelchair Suspension, David J. Smith

Master's Theses

An Advanced Controller for a Semi-Active Wheelchair Suspension was designed, built and tested.  The suspension consisted of a Goodyear 1S3-011 air spring, IQ Valves high speed proportional solenoid valve, and a custom made accumulator.  Several controller designs specific to semi-active suspensions were designed and tested.  The controllers investigated were skyhook, acceleration driven damping, and a combined control law employing both a dual and single sensor version.  The implementation of skyhook control suffered performance degradation from the idealization due to particular elements of hardware, however acceleration driven damping showed a marked and statistically significant improvement over skyhook control, in hardware, by …

The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader

Electronic Theses and Dissertations

The amplitude of the acoustic pressure required to nucleate a gas and/or vapor bubble in a fluid, and to have that bubble undergo an inertial collapse, is termed the inertial cavitation threshold. The hydrostatic dependence of the inertial cavitation threshold was measured up to 30 MPa in ultrapure water using a high quality factor spherical resonator. The threshold increased linearly with the hydrostatic pressure and was found to be temperature dependent. The strength of the bubble collapse at the threshold was measured in terms of shock waves and light emissions. The shock amplitudes increased linearly with the hydrostatic pressure, while …

Reconstruction Resolution Of Coherent Point Sources With Helmholtz Equation Least Squares, Richard Edward Dziklinski

Wayne State University Dissertations

The dissertation investigates the reconstruction of coherent point sources using Helmholtz Equation Least Squares (HELS) method based on measurements in violation of Nearfield Acoustical Holography (NAH) resolution guidelines. In HELS, the Helmholtz equation is solved by matching a series of localized spherical expansion functions to the measured pressures in the field. Expansion coefficients are solved for by least squares and used to reconstruct pressures at the source surface. By approximating the pressure radiation with expansion functions, field and surface pressures can be synthesized, resulting in the possibility of higher spatial resolution than previous generation NAH methods such as Fourier Acoustics …