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Articles 1 - 20 of 20
Full-Text Articles in Acoustics, Dynamics, and Controls
Website: Home, Zhiqu Lu, Likun Zhang, Lei Cao
Website: Home, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
No abstract provided.
Website: Latest Results, Zhiqu Lu, Likun Zhang, Lei Cao
Website: Latest Results, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
No abstract provided.
Website: News And Events, Zhiqu Lu, Likun Zhang, Lei Cao
Website: News And Events, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
No abstract provided.
Investigating The Effects Of Suspended Algal Content, Dissolved Oxygen, And Temperature On A High-Frequency Acoustic Attenuation System In A Controlled Laboratory Environment, Noah Watson
Honors Theses
The Single Frequency Acoustic Attenuation System (SFAAS) has been developed at the National Center for Physical Acoustics (NCPA). This system uses acoustic methods to monitor fine suspended sediment concentration in streams. Site-specific calibrations are necessary for this system, and previous research has indicated that algal concentration or dissolved oxygen concentration of water may affect collected data. Temperature, dissolved oxygen concentration, and fluorescence, used as a proxy for algal concentration, were monitored during this system’s use, and calibrations were derived to account for the effect of each of these variables on acoustic measurements. It has been shown that temperature has a …
Interaction Beyond Nearest Neighbor In Periodic Structures, Sudesh Pathak
Interaction Beyond Nearest Neighbor In Periodic Structures, Sudesh Pathak
Honors Theses
Periodic structures have been of particular interest to researchers and engineers due to their interesting vibrational characteristics leading to applications, namely acoustic filters, and waveguides. Many studies on the interaction of nearest neighbors have been performed. However, such studies are insufficient to understand the variation of band gaps and the maximum number of wave vectors for each frequency. The complex band structure obtained from the interaction beyond nearest neighbors can assist in the development of sophisticated acoustic technologies. This paper primarily emphasizes the study of such interactions with the development of mathematical models based on electrostatic forces, supported by the …
Computational Study On Suppression Of Airfoil Flow Separation Using High-Frequency Translational Surface Actuation, Bibek Gupta
Computational Study On Suppression Of Airfoil Flow Separation Using High-Frequency Translational Surface Actuation, Bibek Gupta
Honors Theses
Flow separation is a phenomenon that occurs when pressure increases in the streamwise direction of a flow, making a distinctive boundary layer or separation bubble. It causes aircraft to experience an increase in drag and noise and a decrease in a lift, hence degrading their aviation performance. This study uses numerical simulations to understand better the effects of high-frequency translational surface actuation (HFTSA) on flow separation control. The numerical simulations mimic the experimental parameters of an experiment performed by Okoye et al. on using the HFTSA system to control flow separation. A symmetrical airfoil structure of chord length of 0.3 …
1. Test Data, Zhiqu Lu, Likun Zhang, Lei Cao
1. Test Data, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains recorded and processed bubble sounds under different conditions: a few bubbles vs. constant flow bubbles. Each condition is tested with nitrogen and with methane.
2. Modeling, Zhiqu Lu, Likun Zhang, Lei Cao
2. Modeling, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains the results for acoustic bubble modeling.
3. Localization, Zhiqu Lu, Likun Zhang, Lei Cao
3. Localization, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains the results for oil leakage source localization.
4. Metadata Files, Zhiqu Lu, Likun Zhang, Lei Cao
4. Metadata Files, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains all ReadMe files for test data, modeling data, and localization data, as well as the corresponding codes.
5. Programs And Algorithms, Zhiqu Lu, Likun Zhang, Lei Cao
5. Programs And Algorithms, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains all codes for the study.
6. Supplemental Materials, Zhiqu Lu, Likun Zhang, Lei Cao
6. Supplemental Materials, Zhiqu Lu, Likun Zhang, Lei Cao
Gulf Research Program Data Sets
This data set contains all conference presentations, manuscripts, technical reports, posters.
Dynamic Characterization Of Duroprotect, A Fiber-Reinforced Ballistics Composite, Ivy A. Turner
Dynamic Characterization Of Duroprotect, A Fiber-Reinforced Ballistics Composite, Ivy A. Turner
Honors Theses
Dynamic characterization of materials has become increasingly common, as it is important to understand how materials behave under sudden loads. Understanding these properties can aid in material selection for novel designs. DuroProtect, a fiber-reinforced ballistics composite developed by Rӧchling, was tested for its dynamic properties at high strain-rates. The Split Hopkinson Pressure Bar (SHPB) test was used to obtain dynamic properties at high strain-rates under compressive loading conditions. Tests were initially conducted to validate force equilibriums for each sample. The data measured from the strain gages mounted on the incident and transmission bars and the elastic wave propagation theories yields …
Elastodynamic Model For Wind Induced Ground Motion, Mohammad Mohammadi
Elastodynamic Model For Wind Induced Ground Motion, Mohammad Mohammadi
Electronic Theses and Dissertations
No abstract provided.
Temperature Dependence Of Shear Speed In Micellar Fluid, E.G. Sunethra Kumari Dayavansha
Temperature Dependence Of Shear Speed In Micellar Fluid, E.G. Sunethra Kumari Dayavansha
Electronic Theses and Dissertations
Wormlike micellar (WM) fluids are viscoelastic and can support shear waves. Phase transitions of the micellar aggregates are temperature dependent and can manifest as sharp changes in the shear wave speed as a function of temperature. Thus, shear waves provide a good tool for detecting the existence of phase transitions. In this work, the variation of shear speed with temperature of 200mM CTAB/NaSal micellar fluid in a 5:3 ratio was studied. The dependence of shear wave speed on time between fluid synthesis and measurement was also investigated. Shear wave propagation through the fluid was observed as a time varying birefringence …
Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction, Johnpaul Russell Abbott
Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction, Johnpaul Russell Abbott
Electronic Theses and Dissertations
A large porous wind barrier enclosure has been built and tested to optimize wind noise reduction at infrasonic frequencies between 0.01-10 Hz in order to develop a technology that is simple, cost effective, and improves upon the limitations of pipe and porous hose arrays. The effects of varying the fence's porosity, modifying its top condition and bottom gap, doubling the height and diameter, and adding a secondary wind barrier were investigated. A simple mathematical model which estimates the wind noise measured at the center of the enclosure was derived based on the measured turbulence and velocity profiles measure outside the …
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Electronic Theses and Dissertations
Aerodynamic noise has been a problem since the first use of the jet engine for military aircraft in World War II. For further uses of the jet engine to be possible, problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities could be considered anechoic, semi-anechoic, or neither. An experiment was designed to determine at what frequencies the National Center for Physical Acoustics' Jet Lab Facility is non-anechoic, semi-anechoic, …
Effects Of A Heated Turbulent Boundary Layer On Surface Pressure Fluctuations, David William Rich
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
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 …
The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader
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 …