Acoustics, Dynamics, and Controls Commons^™

Dynamic Test Scheduling In Hardware-In-The-Loop Simulation Of Commercial Vehicles, Tenil Cletus

Master's Theses

Modern day commercial vehicles are controlled by various Electronic Control Units (ECU). They are not only tested as single units, but also by networking them in Controlled Area Network bus (CAN) to form a complete electrical control system. This is achieved using Hardware In the Loop (HIL) Integration Lab. In HIL, the electrical system is connected to a real time mathematical model of the vehicle plus it’s environment so as to form a loop.

Testing functionality of the electrical system begins by defining functional tests. An example would be testing cruise control activation. Executing each test is made possible by …

Robotic Turret, Daniel Romero, Matthew (Matt) Martelle, Scott Mullens, Rachel Diamant

Mechanical Engineering

No abstract provided.

Predicting The Acoustic Response Of The Golf Club & Ball Impact Using Finite Elements And The Boundary Element Method, Scott Henry Moreira

Master's Theses

An improved and repeatable method for meshing golf club heads using finite elements in TrueGrid® was developed. Using solid brick elements through the thickness of the club head instead of shell elements better represents the many thickness variations throughout each section of a club head. This method also results in a high quality mesh at the center of the club head sections while still maintaining high quality at the edges. A simulation procedure was also developed to predict the acoustic pressure at a designated point in an acoustic medium of a golf club and ball impact using the BEM and …

Dynamic Properties Of Railway Track And Its Components : A State-Of-The-Art Review, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

Recent findings indicate one of major causes of damages, which is attributed to the resonant behaviours, in a railway track and its components. Basically, when a railway track is excited to generalised dynamic loading, the railway track deforms and then vibrates for certain duration. Dynamic responses of the railway track and its components are the key to evaluate the structural capacity of railway track and its components. If a dynamic loading resonates the railway track’s dynamic responses, its components tend to have the significant damage from excessive dynamic stresses. For example, a rail vibration could lead to defects in rails …

Nonlinear Progressive Wave Equation For Stratified Atmospheres, B. Edward Mcdonald, Andrew A. Piacsek

All Faculty Scholarship for the College of the Sciences

The nonlinear progressive wave equation (NPE) [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406–1417 (1987)] is expressed in a form to accommodate changes in the ambient atmospheric density, pressure, and sound speed as the time-stepping computational window moves along a path possibly traversing significant altitude differences (in pressure scale heights). The modification is accomplished by the addition of a stratification term related to that derived in the 1970s for linear range-stepping calculations and later adopted into Khokhlov-Zabolotskaya-Kuznetsov-type nonlinear models. The modified NPE is shown to preserve acoustic energy in a ray tube and yields analytic similarity solutions for …

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 …

Dynamics, Electromyography And Vibroarthrography As Non-Invasive Diagnostic Tools: Investigation Of The Patellofemoral Joint, Filip Leszko

Doctoral Dissertations

The knee joint plays an essential role in the human musculoskeletal system. It has evolved to withstand extreme loading conditions, while providing almost frictionless joint movement. However, its performance may be disrupted by disease, anatomical deformities, soft tissue imbalance or injury. Knee disorders are often puzzling, and accurate diagnosis may be challenging. Current evaluation approach is usually limited to a detailed interview with the patient, careful physical examination and radiographic imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissue conditions. More advanced imaging tools such as MRI or CT are available, …

The Biglobal Instability Of The Bidirectional Vortex, Joshua Will Batterson

Doctoral Dissertations

State of the art research in hydrodynamic stability analysis has moved from classic one-dimensional methods such as the local nonparallel approach and the parabolized stability equations to two-dimensional, biglobal, methods. The paradigm shift toward two dimensional techniques with the ability to accommodate fully three-dimensional base flows is a necessary step toward modeling complex, multidimensional flowfields in modern propulsive applications. Here, we employ a two-dimensional spatial waveform with sinusoidal temporal dependence to reduce the three-dimensional linearized Navier-Stokes equations to their biglobal form. Addressing hydrodynamic stability in this way circumvents the restrictive parallel-flow assumption and admits boundary conditions in the streamwise direction. …

Haptic Tele-Operation Of Wheeled Mobile Robot And Unmanned Aerial Vehicle Over The Internet, Zhiyuan Zuo

Masters Theses

Teleoperation of ground/aerial vehicle extends operator's ability (e.g. expertise, strength, mobility) into the remote environment, and haptic feedback enhances the human operator's perception of the slave environment. In my thesis, two cases are studied: wheeled mobile robot (MWR) haptic tele-driving over the Internet and unmanned aerial vehicle (UAV) haptic teleoperation over the Internet.
We propose novel control frameworks for both dynamic WMR and kinematic WMR in various tele-driving modes, and for a "mixed" UAV with translational dynamics and attitude kinematics.
The recently proposed passive set-position modulation (PSPM) framework is extended to guarantee the passivity and/or stability of the closed-loop system …

Continuously Variable Rotorcraft Propulsion System: Modelling And Simulation, Naveen Kumar Vallabhaneni

Masters Theses

This study explores the variable speed operation and shift response of a prototype of a two speed single path CVT rotorcraft driveline system. Here a Comprehensive Variable Speed Rotorcraft Propulsion system Modeling (CVSRPM) tool is developed and utilized to simulate the drive system dynamics in steady forward speed condition. This investigation attempts to build upon previous variable speed rotorcraft propulsion studies by:

1) Including fully nonlinear first principles based transient gas-turbine engine model

2) Including shaft flexibility

3) Incorporating a basic flight dynamics model to account for interactions with the flight control system.

Through exploring the interactions between the various …

Analytical Solutions For Nonlinear Lateral Sloshing In Partiallyfilled Elliptical Tankers, Hassan Askari

No abstract provided.

Optimization Of The Acoustic Performance Of Polyimide Foams, Olivier Doutres, Noureddine Atalla, Rebecca Wulliman, Shari Ferguson, Steve Bailey

Olivier Doutres Ph.D.

Due to their low weight, high fire resistance and good mechanical strength, SOLIMIDE® Polyimide foams are good candidates for sound packages in aerospace sound transmission applications. However, their high resistance to airflow limits the sound absorption efficiency inside a double wall structure and thus the sound transmission loss of the structure. The paper discusses two concepts to improve the transmission efficiency of such materials for double wall applications: (i) improving its sound absorption behavior by removing mechanically or chemically the cell membranes and thus decreasing both the flow resistance and tortuosity, (ii) coupling the Polyimide foams to screens (porous or …

A Practical Impedance Tube Method To Estimate The Normal Incidence Sound Transmission Loss Of Double Wall Structure, Olivier Doutres, Noureddine Atalla

Olivier Doutres Ph.D.

The objective of this paper is to propose a practical impedance tube method to optimize the sound transmission loss of double wall structure by concentrating on the sound package placed inside the structure. In a previous work, the authors derived an expression that breaks down the transmission loss of a double wall structure containing a sound absorbing blanket separated from the panels by air layers in terms of three main contributions; (i) sound transmission loss of the panels, (ii) sound transmission loss of the blanket and (iii) sound absorption due to multiple reflections inside the cavity. The sound transmission loss …

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, Thesis, 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 …

Effect Of Unsteady Combustion On The Stability Of Rocket Engines, Tina Morina Rice

Doctoral Dissertations

Combustion instability is a problem that has plagued the development of rocket-propelled devices since their conception. It is characterized by the occurrence of high-frequency nonlinear gas oscillations inside the combustion chamber. This phenomenon degrades system performance and can result in damage to both structure and instrumentation.

The goal of this dissertation is to clarify the role of unsteady combustion in the combustor instability problem by providing the first quantified estimates of its effect upon the stability of liquid rocket engines. The combination of this research with a new system energy balance method, accounting for all dynamic interactions within a system, …

Solar Decathlon Controls, James Mitchel Routh, Travis Lathrop, Colby Jarrett, Zach Cross

Chancellor’s Honors Program Projects

No abstract provided.

Resonance Testing For Fault Detection Of Steam Generator Heat Transfer Tubing Walls, Michael C. Shannon, John Howington, Jesus Sanchez, Colin Sandidge, Jeremy Townsend, Keith Welsh

Chancellor’s Honors Program Projects

No abstract provided.

Method For Determination Of Complex Moduli Associated With Viscoelastic Material, Russell Scott Garner

Masters Theses

The aerospace industry is utilizing low cost miniature inertial measurement units (IMUs) that employ Micro Electro-Mechanical Systems (MEMS) technology in an effort to reduce size, weight, and cost of systems. A drawback of these MEMS devices is they are sensitive to vibration, shock and acoustic environments, which limits the usefulness of such devices in the severe environments imposed by many aerospace applications. In an effort to reduce the vibration, shock and acoustic environments experienced by these MEMS devices, the desire to develop passive damping treatments to structural components used to mount these devices. The damping treatments can be applied at …

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 …

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

Aviation Department Publications

No abstract provided.

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

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, 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.

Numerical Forcing Of Horizontally-Homogeneous Stratified Turbulence, Kaustubh J. Rao

Masters Theses 1911 - February 2014

It is often desirable to study simulated turbulent flows at steady state even if the flow has no inherent source of turbulence kinetic energy. Doing so requires a numerical forcing scheme and various methods have been studied extensively for turbulence that is isotropic and homogeneous in three dimensions. A review of these existing schemes is used to form a framework for more general forcing methods. In this framework, the problem of developing a forcing scheme in Fourier space is abstracted into the two problems of (1) prescribing the spectrum of the input power and (2) specifying a force that has …