Acoustics, Dynamics, and Controls Commons^™

Effects Of Noise, Reverberation And Foreign Accent On Native And Non-Native Listeners’ Performance Of English Speech Comprehension, Zhao Ellen Peng, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A large number of non-native English speakers may be found in American classrooms, both as listeners and talkers. Little is known about how this population comprehends speech in realistic adverse acoustical conditions. A study was conducted to investigate the effects of background noise level (BNL), reverberation time (RT), and talker foreign accent on native and non-native listeners' speech comprehension, while controlling for English language abilities. A total of 115 adult listeners completed comprehension tasks under 15 acoustic conditions: three BNLs (RC-30, RC-40, and RC-50) and five RTs (from 0.4 to 1.2 s). Fifty-six listeners were tested with speech from native …

Design And Optimization Of Membrane-Type Acoustic Metamaterials, Matthew G. Blevins

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

One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes …

On The Scattering Of An Acoustic Plane Wave By A Soft Prolate Spheroid, Joseph Michael Borromeo

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis solves the scattering problem in which an acoustic plane wave of propagation number K1 is scattered by a soft prolate spheroid. The interior field of the scatterer is characterized by a propagation number K2, while the field radiated by the scatterer is characterized by the propagation number K3. The three fields and their normal derivatives satisfy boundary conditions at the surface of the scatterer. These boundary conditions involve six complex parameters depending on the propagation numbers. The scattered wave also satisfies the Sommerfeld radiation condition at infinity. Through analytical methods, series representations are constructed for the interior field …

The Effects Of Ball Interactions On The Dynamic Behavior Of A Ball Balancer Rotating At Speeds Above The Translational Resonant Frequency Of The System., Gregory A. Dedow

Electronic Theses and Dissertations

Many applications are inherently rotational in nature. These applications range from industrial products to consumer products. As seen in a traditional frequency response plot, the motion of a rotating imbalance does not approach zero as the forcing frequency is increased. Unlike a traditional forced mass spring oscillator, the motion of the rotating imbalance approaches some non-zero value. To account for this residual motion, some systems utilize a balancing device to reduce this motion. These balancing devices can be passive or active, depending on the design considerations. This paper will focus on the traditional, passive ball-type balancer due to its simplicity …

Preliminary Design Tools In Turbomachinery: Non-Uniformly Spaced Blade Rows, Multistage Interaction, Unsteady Radial Waves, And Propeller Horizontal-Axis Turbine Optimization, Yujun Leng

Open Access Dissertations

Turbomachinery flow fields are inherently unsteady and complex which makes the related CFD analyses computationally intensive. Physically based preliminary design tools are desirable for parametric studies early in the design stage, and to provide deep physical insight and a good starting point for the later CFD analyses. Four analytical/semi-analytical models are developed in this study: 1) a generalized flat plate cascade model for investigating the unsteady aerodynamics of a blade row with non-uniformly spaced blades; 2) a multistage interaction model for investigating rotor-stator interactions; 3) an analytical solution for quantifying the impeller wake convection and pressure wave propagating between a …

Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie

Faculty Publications

In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom …

Performance Metrics For Depth-Based Signal Separation Using Deep Vertical Line Arrays, Gabriel Paul Kniffin, John Kenneth Boyle, Lisa Zurk, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

A recent publication by McCargar and Zurk [(2013). J. Acoust. Soc. Am. 133(4), EL320–EL325] introduced a modified Fourier transform-based method for passive source depth estimation using vertical line arrays deployed below the critical depth in the deep ocean. This method utilizes the depth-dependent modulation caused by the interference between the direct and surface-reflected acoustic arrivals, the observation of which is enhanced by propagation through the reliable acoustic path. However, neither the performance of this method nor its limits of applicability have yet been thoroughly investigated. This paper addresses both of these issues; the first by identifying and analyzing the factors …

Orchard Bin Atv Trailer, Neil F. Leitz

All Undergraduate Projects

A local orchardist was experiencing a problem that was being caused by their lack of apple picking bin moving equipment. The orchardist needed a well-engineered solution to this lack of equipment. The solution arrived at was a five bin trailer. There were multiple design requirements for this trailer, including the device needing to be able to interface with an ATV, be able to be loaded by hand, be able to carry five bins, and not exceed a budget of $750. While perfecting the design of the trailer, a number of different disciplines were utilized, which included dynamics, kinematics, static loading …

Flag Raising Device, Josh Quintero

All Undergraduate Projects

The motivation for this project stems from a lifetime of boating with father Richard Jones. One problem that many people encounter, including Richard, was when towing someone behind a boat, is the difficulty with handling the warning flag. This flag is used to show other surrounding boats that someone has fallen into the water behind their boat. This warns other boats to stay far away from that area to keep safe from running over the swimmer. Although, when holding the flag in the boat, it can be hard to see at times. The boat driver, or other people standing in …

3d Infrastructure Condition Assessment For Rail Highway Applications, Teng Wang

Theses and Dissertations--Civil Engineering

Highway roughness is a concern for both the motoring public and highway authorities. Roughness may even increase the risk of crashes. Rail-highway grade crossings are particularly problematic. Roughness may be due to deterioration or simply due to the way the crossing was built to accommodate grade change, local utilities, or rail elevation. With over 216,000 crossings in the US, maintenance is a vast undertaking. While methods are available to quantify highway roughness, no method exists to quantitatively assess the condition of rail crossings. Conventional inspection relies on a labor-intensive process of qualitative judgment. A quantifiable, objective and extensible procedure for …

Power Maximization For Pyroelectric, Piezoelectric, And Hybrid Energy Harvesting, Murtadha A. Shaheen

Theses and Dissertations

The goal of this dissertation consists of improving the efficiency of energy harvesting using pyroelectric and piezoelectric materials in a system by the proper characterization of electrical parameters, widening frequency, and coupling of both effects with the appropriate parameters.

A new simple stand-alone method of characterizing the impedance of a pyroelectric cell has been demonstrated. This method utilizes a Pyroelectric single pole low pass filter technique, PSLPF. Utilizing the properties of a PSLPF, where a known input voltage is applied and capacitance C_p and resistance R_p can be calculated at a frequency of 1 mHz to 1 Hz. …

Studies To Improve Exhaust System Acoustic Performance By Determination And Assessment Of The Source Characteristics And Impedance Optimization, Yitian Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

It is shown that the relationship between an impedance change and the dynamic response of a linear system is in the form of the Moebius transformation. The Moebius transformation is a conformal complex transformation that maps straight lines and circles in one complex plane into straight lines and circles in another complex plane. The center and radius of the mapped circle can be predicted provided that all the complex coefficients are known. This feature enables rapid determination of the optimal impedance change to achieve desired performance.

This dissertation is primarily focused on the application of the Moebius transformation to enhance …

Incorporating Driver’S Behavior Into Predictive Powertrain Energy Management For A Power-Split Hybrid Electric Vehicle, Lei Feng

Dissertations, Master's Theses and Master's Reports

The goal of this series of research is to advance hybrid electric vehicle (HEV) energy management by incorporating driver’s driving behavior and driving cycle information. To reduce HEV fuel consumption, the objectives of this research are divided into the following three parts.

The first part of the research investigates the impact of driver’s behavior on the overall fuel efficiency of a hybrid electric vehicle and the energy efficiency of individual powertrain components under various driving cycles. Between the sticker number fuel economy and actual fuel economy, it is well known that a noticeable difference occur when a driver drives aggressively. …

Methodology For Analyzing Epoxy-Cnt Phononic Crystals For Wave Attenuation And Guiding, Madhu Kolati

Dissertations, Master's Theses and Master's Reports

Phononic crystals (PhnCs) control, direct and manipulate sound waves to achieve wave guiding and attenuation. This dissertation presents methodology for analyzing nanotube materials based phononic crystals to achieve control over sound, vibration and stress mitigation. Much of the analytical work presented is in identifying frequency band gaps in which sound or vibration cannot propagate through these PhnCs. Wave attenuation and mitigation analysis is demonstrated using finite element simulation. Engineering principles from current research areas of solid mechanics, solid-state physics, elasto-dynamics, mechanical vibrations and acoustics are employed for the methodology. A considerable effort is put to show that these PhnCs can …

The University Of Akron Human Powered Vehicle Team, Maria E. Rizzo, Andrew J. Derhammer, Christopher M. Trowbridge, Timothy M. Nutt, Joseph R. Boyd, Jeremy W. Marcum, Jonathan E. Adams, Donald G. Haiss, Julia Wood, Brian D. Goshia, Scott T. Fagan, Joshua D. Everhard, Rebecca L. Slivka

Williams Honors College, Honors Research Projects

The University of Akron Human Powered Vehicle Team’s 2016 vehicle, Klokan, was designed, manufactured and tested with safety, reliability, performance and ease of use in mind. The vehicle is a fully faired tadpole trike with a lightweight aluminum frame constructed from 6061-T6 tubing having a total weight of 8.9 lbs. To complement the lightweight frame, the fairing is constructed from polycarbonate, PETG and carbon fiber strips which combine into a lightweight, easy to manufacture weather barrier and aerodynamic structure. Klokan was designed to be a safe and efficient mode of everyday transportation which ensures that riders are sufficiently protected by …

Drive Signal Development For The Thermoacoustic Loudspeaker, Troy Bouman

Dissertations, Master's Theses and Master's Reports

Carbon nanotube thermophones can create acoustic waves from 1 Hz to 100 kHz. The thermoacoustic effect that allows for this non-vibrating sound source is naturally inefficient. Prior efforts have not explored their true efficiency (i.e. the ratio of the total acoustic power to the electrical input power). All previous works have used the ratio of sound pressure to input electrical power. A method for true power efficiency measurement is shown using a fully anechoic technique. True efficiency data are presented for five different drive signal processing techniques: standard alternating current (AC), direct current added to AC (DCAC), amplitude modulation of …

Design, Fabrication And Analysis Of An Auxiliary Power Unit On A Heavy-Duty Truck To Power The Hvac Systems Of The Truck During Driver Off-Duty Conditions, Rohan Milind Kalurkar

Dissertations, Master's Theses and Master's Reports

Currently, one of the biggest challenges the world is facing is energy insufficiency. One of the contributors to energy consumption in United States are the idling semi-trailer trucks. In May 2001, President Bush issued The National Energy Policy in which he directed The Environmental Protection Agency (EPA) and Department of Transportation (DOT) to reduce the idling of trucks. This was done in order to reduce energy consumption by lowering fuel consumption and emissions coming out of semi-trailer trucks in the United States of America.

This project deals with the efforts of installing an Auxiliary Power Unit (APU) as a device …

Experimental Study, Modelling And Controller Design For An Rcci Engine, Naga Nithin Teja Kondipati

Dissertations, Master's Theses and Master's Reports

Low Temperature Combustion (LTC) has got widespread attention over the past two decades in the field of Automotive Research and Development due to it’s potential for achieving higher efficiencies with near-zero engine out NOx and soot emissions. Among all the LTC strategies Reactivity controlled compression ignition (RCCI) has shown the most promising results due to it’s precise control over combustion phasing and heat release rate. However, RCCI being a dual-fuel stratified combustion, precise control over the injection timing of direct injected fuel and in-cylinder fuel reactivity of the mixture needs to be controlled effectively in order to achieve gross indicated …

Evaluation Of Angular Distribution Of Incident Field At The Transmission Loss Window In Michigan Tech’S Reverberant Chamber, Abhishek Thyagarajan

Dissertations, Master's Theses and Master's Reports

Transmission Loss prediction accuracy is highly dependent on a good understanding of the angular distribution of incident field on the panel. Traditionally, the incident field has been assumed to be either completely random (equal probability of incidence at all angles from 0° - 90°) or field incidence (where the field is assumed to be completely diffuse between 0° - 78°). Studies1-3 have shown that these models are not completely representative of the incident field. This incident field is studied in the Michigan Tech Transmission Loss suite using two different methods in this study; beamforming and acoustic intensity. The beamforming method …

Tractor Hydraulic Power Data Acquisition System, J. B.W. Roeber, Santosh Pitla, Michael F. Kocher, Joe D. Luck, Roger M. Hoy

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Tractor hydraulic power is used on a wide range of agricultural implements; however, the availability of operational hydraulic data at points other than full engine throttle position is limited. Operators could utilize this hydraulic data to maximize field efficiency and minimize machinery costs when determining suitable machinery for field operations. A field usable hydraulic test apparatus capable of measuring tractor hydraulic pressure and flow rate data was developed. The goal of this study was to determine if a hydraulic flow and pressure measurement device could be installed on the rear of a tractor to provide implement hydraulic power consumption at …