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Central Washington University

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Articles 1 - 11 of 11

Full-Text Articles in Acoustics, Dynamics, and Controls

Experimental Uncertainty In Measurements Of Violin Impulse Response, Andrew Piacsek, Seth Lowery Jan 2023

Experimental Uncertainty In Measurements Of Violin Impulse Response, Andrew Piacsek, Seth Lowery

All Faculty Scholarship for the College of the Sciences

Experiments that investigate how an individual musical instrument changes in response to subtle alterations must contend with measurement uncertainty, which typically arises from inconsistencies in the measurement setup. We quantify uncertainty in violin response measurements by measuring bridge admittance and radiatively of a single instrument that is repeatedly removed and reinstalled in our measurement apparatus. From this set of baseline measurements, we calculate the average and standard deviation of admittance and radiativity. The amount of variation observed in the baseline data is compared to the change in bridge admittance that occurred over several days due to a large and abrupt …


Design Of Broadband Helmholtz Resonator Arrays Using The Radiation Impedance Method, Vidhya Rajendran, Andy Piacsek, Tomás Méndez Echenagucia Jan 2022

Design Of Broadband Helmholtz Resonator Arrays Using The Radiation Impedance Method, Vidhya Rajendran, Andy Piacsek, Tomás Méndez Echenagucia

All Faculty Scholarship for the College of the Sciences

This paper describes the design process of a low-frequency sound absorptive panel composed of differently tuned Helmholtz resonators (HRs), considering size and fabrication constraints relevant for applications in the building sector. The paper focuses on cylindrical and spiral resonators with embedded necks that are thin and can achieve high absorption. the mutual interaction between the resonators was modeled based on the radiation impedance method and it plays a key component in enhancing the absorption performance of the array. The differential evolution search algorithm was used to design the resonators and modify their mutual interaction to derive the absorption performance of …


R/C Baja: Drivetrain, Connor T. Donovan Jan 2022

R/C Baja: Drivetrain, Connor T. Donovan

All Undergraduate Projects

The Central Washington University Mechanical Engineering Technology Department hosts an annual R/C Baja competition in which R/C cars fabricated by student teams are put through a series of courses and tests to determine which team's vehicle is best. The goal of this project was to create a functioning drivetrain that conveys power from the battery to the wheels and provides control of the vehicle. A list of requirements for the drivetrain was created to ensure that the vehicle will not only function, but that it will actually succeed in the competition. These requirements included that the vehicle must achieve a …


Jcati Carbon Fiber Shredder 2022, Parker Sudderth Jan 2022

Jcati Carbon Fiber Shredder 2022, Parker Sudderth

All Undergraduate Projects

This project is a potential solution to keep the carbon fiber waste from airplane manufacturing to a minimum, sponsored by the Joint Center for Aerospace Technology Innovation (JCATI). The design and assembly will be scalable for future industry application. The overall design of the whole carbon fiber recycler consists of a crusher, shredder, and oven. This report is on the caron fiber shredder module. The shredder is tasked with being able to shred the delaminated carbon fiber scrap that directly comes from the crusher. The operation must produce shreds in the proper size to be gathered and delivered to the …


Dual-Axis Solar Tracker, Bryan Kennedy Jan 2020

Dual-Axis Solar Tracker, Bryan Kennedy

All Undergraduate Projects

Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in …


Composite Recycler: Frame, Alfonso Olivera Jan 2019

Composite Recycler: Frame, Alfonso Olivera

All Undergraduate Projects

How can composites be recycled? The Composite Recycler is an ongoing project that started in September 2017. The purpose of this project was to create a machine that will delaminate the composites, cut them, and heat them up to separate the resin from the composites so they can be recycled. A group was put together for the 2018-2019 academic year to further the project as a whole improve the operation of the device. The existing base was used as well as the cutter and the power sources. The upgrades included; a housing to support the transport rollers and changing from …


Development Of An Excel® Rocket Simulator For Application In Middle School, High-School, And University Stem Education, Melvin Lee Hortman Jan 2017

Development Of An Excel® Rocket Simulator For Application In Middle School, High-School, And University Stem Education, Melvin Lee Hortman

All Master's Theses

Water rocket activities are one of the most popular STEM activities used in primary, secondary, and higher education yet are void of engineering, though engineering is heavily implied in the STEM acronym. This study investigated the amount of engineering present in water rocket activities, and options for emphasizing engineering more in water rocket activities using an open-platform flight simulator for use by educators to enable students to predict flight parameters of a water rocket they designed, and test those predictions against experimental data. The simulator was constructed in Excel® with many functions, but the function validated in this study was …


Orchard Bin Atv Trailer, Neil F. Leitz Jan 2016

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 Jan 2016

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 …


Resonance Frequencies Of A Spherical Aluminum Shell Subject To Static Internal Pressure, Andrew A. Piacsek, Sami Abdul-Wahid, Robert Taylor May 2012

Resonance Frequencies Of A Spherical Aluminum Shell Subject To Static Internal Pressure, Andrew A. Piacsek, Sami Abdul-Wahid, Robert Taylor

All Faculty Scholarship for the College of the Sciences

Measurements of the vibrational response of a spherical aluminum shell subject to changes in the interior pressure clearly demonstrate that resonance frequencies shift higher as the pressure is increased. The frequency shift appears to be smaller for longitudinal modes than for bending wave modes. The magnitude of frequency shift is comparable to analytical predictions made for thin cylindrical shells. Changes in the amplitudes of resonance peaks are also observed. A possible application of this result is a method for noninvasively monitoring pressure changes inside sealed containers, including intracranial pressure in humans.


Nonlinear Progressive Wave Equation For Stratified Atmospheres, B. Edward Mcdonald, Andrew A. Piacsek Nov 2011

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 …