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You searched for +publisher:"University of Colorado" +contributor:("David R Kassoy"). Showing records 1 – 3 of 3 total matches.

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University of Colorado

1. Becker, Collin R. Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics.

Degree: PhD, Mechanical Engineering, 2010, University of Colorado

Porous silicon (PS) is a silicon (Si) based material composed of pores with diameters ranging from several nanometers to several micrometers. Typically PS is formed by electrochemically etching a Si wafer in a hydrofluoric acid (HF) based electrolyte. This route requires a custom built etch cell and a power supply and is difficult to integrate with the batch processing techniques of conventional Microsystems fabrication. In the first part of this work, a galvanic etching approach is used to fabricate PS in which neither a power supply nor custom etch cell are required. Galvanic etching methods are developed to fabricate thick, mechanically stable PS on lightly doped p-type Si wafers. A detailed characterization of galvanic PS, including specific surface area measurements, etch rates, high resolution transmission electron microscopy, and photoluminescence measurements, is also presented. As a means to model galvanic Si etching (corrosion) on Si Microsystems, we present a finite element method (FEM) enabled simulation. In the second half of this work, galvanic PS for nanoenergetics is investigated. Nanoenergetic composite materials are composed of nanometer-scale fuel and oxidizer components that have energy release rates much greater than the bulk materials. In this case, PS fuel is impregnated with sodium perchlorate (NaClO4) oxidizer to yield a nanoenergetic composite. The data presented here include the first measurements of nanoenergetic PS using thermal analysis techniques including bomb calorimetry and differential scanning calorimetry (DSC). Additionally, the reaction products are revealed to be composed of nearly spherical, interconnected nanoparticles of amorphous silica. Using bomb calorimetry, the heat of reaction of galvanic PS-NaClO4 nanoenergetic composites is determined to be 9.9 ± 1.8 kJ/g and 27.3 ± 3.2 kJ/g of PS when ignited under N2 and O2, respectively. DSC, coupled with Fourier transform infrared spectroscopy (FTIR) data, reveals that the energy output is dependent on the hydrogen termination of the PS. Lastly, the flame propagation velocity of the PS-NaClO4 composite is measured with a novel on-chip diagnostic technique and high-speed video data taken at 930,000 frames per second. A velocity averaging ~3,050 m/s is observed, and is currently the fastest velocity reported for nanoenergetic materials. Advisors/Committee Members: Conrad R Stoldt, Victor M Bright, David R Kassoy.

Subjects/Keywords: galvanic corrosion; MEMS; nanoenergetics; nanoparticle; photoluminescence; porous silicon; Materials Science and Engineering; Mechanical Engineering; Nanoscience and Nanotechnology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Becker, C. R. (2010). Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/mcen_gradetds/12

Chicago Manual of Style (16th Edition):

Becker, Collin R. “Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics.” 2010. Doctoral Dissertation, University of Colorado. Accessed March 22, 2019. http://scholar.colorado.edu/mcen_gradetds/12.

MLA Handbook (7th Edition):

Becker, Collin R. “Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics.” 2010. Web. 22 Mar 2019.

Vancouver:

Becker CR. Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics. [Internet] [Doctoral dissertation]. University of Colorado; 2010. [cited 2019 Mar 22]. Available from: http://scholar.colorado.edu/mcen_gradetds/12.

Council of Science Editors:

Becker CR. Galvanic Porous Silicon: Processing and Characterization for Nanoenergetics. [Doctoral Dissertation]. University of Colorado; 2010. Available from: http://scholar.colorado.edu/mcen_gradetds/12


University of Colorado

2. Reckinger, Shanon Marie. Adaptive Wavelet-Based Ocean Circulation Modeling.

Degree: PhD, Mechanical Engineering, 2011, University of Colorado

Ocean modeling is a crucial component in understanding our climate system. The advancement of the numerical methods used for ocean modeling is the focus of this dissertation. In this work, an integrated approach for modeling common ocean test problems, western boundary currents, and tsunamis on adaptive grids using novel boundary techniques is considered. The use of the adaptive wavelet collocation method is explored for these ocean problems. This method solves the governing equations on temporally and spatially varying meshes, which allows higher effective resolution to be obtained with less computational cost. In addition to developing wavelet-based computational models, this work also sets out to improve the representation of continental topology and bottom bathymetry through several extensions of the Brinkman volume penalization methods. Due to the complicated geometry inherent in ocean boundaries, the stair-step representation used in the majority of current global ocean circulation models causes accuracy and numerical stability problems. Brinkman penalization is a numerical technique used to enforce no slip boundary conditions through the addition of a term to the governing equations. When coupled with the adaptive wavelet collocation method, the flow near the boundary can be well resolved. It is especially useful for simulations of boundary currents and tsunamis, where flow near the boundary is important. This thesis can be viewed as a proof of concept. The general foundation is established for future, more specific, applications. Advisors/Committee Members: Oleg V. Vasilyev, David R. Kassoy, Olivier Desjardins.

Subjects/Keywords: adaptive grid; boundary currents; immersed boundary method; ocean modeling; tsunami; wavelets; Applied Mathematics; Mechanical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Reckinger, S. M. (2011). Adaptive Wavelet-Based Ocean Circulation Modeling. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/mcen_gradetds/29

Chicago Manual of Style (16th Edition):

Reckinger, Shanon Marie. “Adaptive Wavelet-Based Ocean Circulation Modeling.” 2011. Doctoral Dissertation, University of Colorado. Accessed March 22, 2019. http://scholar.colorado.edu/mcen_gradetds/29.

MLA Handbook (7th Edition):

Reckinger, Shanon Marie. “Adaptive Wavelet-Based Ocean Circulation Modeling.” 2011. Web. 22 Mar 2019.

Vancouver:

Reckinger SM. Adaptive Wavelet-Based Ocean Circulation Modeling. [Internet] [Doctoral dissertation]. University of Colorado; 2011. [cited 2019 Mar 22]. Available from: http://scholar.colorado.edu/mcen_gradetds/29.

Council of Science Editors:

Reckinger SM. Adaptive Wavelet-Based Ocean Circulation Modeling. [Doctoral Dissertation]. University of Colorado; 2011. Available from: http://scholar.colorado.edu/mcen_gradetds/29


University of Colorado

3. Reckinger, Scott James. Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability.

Degree: PhD, Mechanical Engineering, 2013, University of Colorado

The compressible Rayleigh-Taylor instability (RTI) occurs when a fluid of low molar mass supports a fluid of higher molar mass against a gravity-like body force or in the presence of an accelerating front. Intrinsic to the problem are highly stratified background states, acoustic waves, and a wide range of physical scales. The objective of this thesis is to develop a specialized computational framework that addresses these challenges and to apply the advanced methodologies for direct numerical simulations of compressible RTI. Simulations are performed using the Parallel Adaptive Wavelet Collocation Method (PAWCM). Due to the physics-based adaptivity and direct error control of the method, PAWCM is ideal for resolving the wide range of scales present in RTI growth. Characteristics-based non-reflecting boundary conditions are developed for highly stratified systems to be used in conjunction with PAWCM. This combination allows for extremely long domains, which is necessary for observing the late time growth of compressible RTI. Initial conditions that minimize acoustic disturbances are also developed. The initialization is consistent with linear stability theory, where the background state consists of two diffusively mixed stratified fluids of differing molar masses. The compressibility effects on the departure from the linear growth, the onset of strong non-linear interactions, and the late-time behavior of the fluid structures are investigated. It is discovered that, for the thermal equilibrium case, the background stratification acts to suppress the instability growth when the molar mass difference is small. A reversal in this monotonic behavior is observed for large molar mass differences, where stratification enhances the bubble growth. Stratification also affects the vortex creation and the associated induced velocities. The enhancement and suppression of the RTI growth has important consequences for a detailed understanding of supernovae flame front acceleration and fuel capsule designs for inertial confinement fusion. Advisors/Committee Members: Oleg V. Vasilyev, Daniel Livescu, David R. Kassoy, Peter E. Hamlington, John P. Crimaldi.

Subjects/Keywords: Compressibility; Computational Framework; Rayleigh-Taylor Instability; Stratification; Vorticity Production; Wavelets; Applied Mathematics; Mechanical Engineering; Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Reckinger, S. J. (2013). Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/mcen_gradetds/63

Chicago Manual of Style (16th Edition):

Reckinger, Scott James. “Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability.” 2013. Doctoral Dissertation, University of Colorado. Accessed March 22, 2019. http://scholar.colorado.edu/mcen_gradetds/63.

MLA Handbook (7th Edition):

Reckinger, Scott James. “Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability.” 2013. Web. 22 Mar 2019.

Vancouver:

Reckinger SJ. Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2019 Mar 22]. Available from: http://scholar.colorado.edu/mcen_gradetds/63.

Council of Science Editors:

Reckinger SJ. Adaptive Wavelet-Based Direct Numerical Simulations of Rayleigh-Taylor Instability. [Doctoral Dissertation]. University of Colorado; 2013. Available from: http://scholar.colorado.edu/mcen_gradetds/63

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