+publisher:"Penn State University" +contributor:("Francesco Costanzo, Committee Member")

Penn State University

1. Chillara, Vamshi Krishna. Towards improved Nde and Shm methodologies incorporating nonlinear structural features.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/26354

► Ultrasound is widely employed in Nondestructive Evaluation (NDE) and Structural Health Monitoring (SHM) applications to detect and characterize damage/defects in materials. In particular, ultrasonic guided… (more)

▼ Ultrasound is widely employed in Nondestructive Evaluation (NDE) and Structural Health Monitoring (SHM) applications to detect and characterize damage/defects in materials. In particular, ultrasonic guided waves are considered a foremost candidate for in-situ monitoring applications. Conventional ultrasonic techniques rely on changes/discontinuities in linear elastic material properties, namely the Young's modulus and shear modulus to detect damage. On the other hand, nonlinear ultrasonic techniques that rely on micro-scale nonlinear material/structural behavior are proven to be sensitive to damage induced microstructural changes that precede macro-scale damage and are hence capable of early damage detection. The goal of this thesis is to investigate the capabilities of nonlinear guided waves – a fusion of nonlinear ultrasonic techniques with the guided wave methodologies for early damage detection. To that end, the thesis focuses on two important aspects of the problem: Wavemechanics - deals with ultrasonic guided wave propagation in nonlinear waveguides; Micromechanics - deals with correlating ultrasonic response with micro-scale nonlinear material behavior. For the development of efficient NDE and SHM methodologies that incorporate nonlinear structural features, a detailed understanding of the above aspects is indispensable. In this thesis, the wavemechanics aspect of the problem is dealt with from both theoretical and numerical standpoints. A generalized theoretical framework is developed to study higher harmonic guided waves in plates. This was employed to study second harmonic guided waves in pipes using a large-radius asymptotic approximation. Second harmonic guided waves in plates are studied from a numerical standpoint. Theoretical predictions are validated and some key aspects of higher harmonic generation in waveguides are outlined. Finally, second harmonic guided waves in plates with inhomogeneous and localized nonlinearities are studied and some important aspects of guided wave mode selection are addressed. The other part of the work focused on developing a micromechanics based understanding of ultrasonic higher harmonic generation. Three important aspects of micro-scale material behavior, namely tension-compression asymmetry, shear-normal coupling and deformation induced asymmetry are identified and their role in ultrasonic higher harmonic generation is discussed. Tension-compression asymmetry is identified to cause second (even) harmonic generation in materials. Then, shear-normal coupling is identified to cause generation of secondary waves of different polarity than the primary waves. In addition, deformation induced anisotropy due to the presence of residual stress/strain and its contribution to ultrasonic higher harmonic generation is qualitatively discussed. Also, the tension-compression asymmetry in the material is quantified using an energy based measure. The above measure is employed to develop a homogenization based approach amenable to multi-scale analysis to correlate microstructure… Advisors/Committee Members: Clifford Jesse Lissenden Iii, Dissertation Advisor/Co-Advisor, Joseph Lawrence Rose, Committee Member, Francesco Costanzo, Committee Member, Panagiotis Michaleris, Committee Member.

Subjects/Keywords: NDE; SHM; Nonlinear ultrasonics; nonlinear guided waves; micromechanics; microstructure characterization; homogenization

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APA (6^th Edition):

Chillara, V. K. (2015). Towards improved Nde and Shm methodologies incorporating nonlinear structural features. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/26354

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Chillara, Vamshi Krishna. “Towards improved Nde and Shm methodologies incorporating nonlinear structural features.” 2015. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/26354.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Chillara, Vamshi Krishna. “Towards improved Nde and Shm methodologies incorporating nonlinear structural features.” 2015. Web. 06 Mar 2021.

Vancouver:

Chillara VK. Towards improved Nde and Shm methodologies incorporating nonlinear structural features. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/26354.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Chillara VK. Towards improved Nde and Shm methodologies incorporating nonlinear structural features. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/26354

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

2. Yashinski , Melisa Sue. Effect of Large Elastic Strains on Phonons in GaP Nanowires.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15148

► Phonon deformation potentials (PDPs) directly relate shifts in phonon frequency, measured through Raman spectroscopy, to strain in a material. To measure a material's PDPs, one… (more)

▼ Phonon deformation potentials (PDPs) directly relate shifts in phonon frequency, measured through Raman spectroscopy, to strain in a material. To measure a material's PDPs, one needs to decouple the PDP dependence on phonon shift rate by measuring multiple shift rates. This is possible through uniaxial tension, which distorts the shape of the crystal causing phonons that are degenerate at zero strain to split and shift at different rates. Historically, PDPs have been measured on bulk samples under uniaxial compression up to fairly low strains and total phonon shifts. This thesis has clearly shown that PDPs not measured up to high enough strains to induce visible phonon splitting are flawed. The implementation of flawed PDPs leads to an overestimated strain measurement and underestimated properties such as elastic modulus. This study has used a GaP nanowire model system that is capable of withstanding large strains before failure that enabled highly accurate PDP measurements. This study has also generalized phonon deformation theory so that, when combined with accurate PDPs, reliable strain and material property measurements are possible on any specimen independent of scale, geometry, or testing condition. Therefore the application of accurate PDPs to phonon deformation theory extends to a variety of experiments that rely on Raman spectroscopy to quantify strain in the material, including, but not limited to: assessing strain transfer in a fiber embedded matrix under different loading conditions; measuring stress distribution in metal-oxide-semiconductor (MOS) devices in order to better predict failure; characterizing residual stress due to crystallographic mismatch in materials such as superlattices and core-shell wires; and quantifying the effects of varying defect densities on the mechanical properties of a material. Tensile experiments were performed on ten [111] oriented GaP nanowires with diameters ranging from 53 to 260 nm, five of which included PDP measurements. These GaP nanowires exhibited fairly high tensile strengths (1.09 GPa <= 4.97 GPa) and large phonon frequency shifts (up to 9.22 cm^(-1) in the LO phonon, 13.6 cm^(-1) in the TO1 phonon, and 22.2 cm^-1 in the TO2 phonon). Phonon shift rates measured in the TO₂ phonon were used to measure the PDPs of GaP: gamma=(-p+2q)(6w²)=2.99 +/- 0.63 and r/w²=-1.27 +/- 0.46. These PDPs were used to determine strains to failure ranging from 0.70% to 3.69% and experimental elastic moduli ranging from 112.6 to 208.3 GPa from the LO data, 144.5 to 169.7 GPa from the TO1 data, and 158.8 to 168.8 GPa from the TO2 data. These experimental moduli matched closely to the theoretical elastic modulus of [111] GaP (E=166.7 GPa) determined in the strength model implemented in this thesis. The PDPs measured in this study were higher and predicted larger phonon shift rates than PDPs measured on bulk GaP [Balslev 1974]. Strains to failure determined from bulk PDPs (1.57% to 21.6%) were unrealistically high and the corresponding elastic moduli (14.7 to 86.8 GPa) were… Advisors/Committee Members: Christopher Muhlstein, Dissertation Advisor/Co-Advisor, Joan Marie Redwing, Committee Member, Suzanne E Mohney, Committee Member, Francesco Costanzo, Committee Member.

Subjects/Keywords: Nanowires; Gallium Phosphide; GaP; Mechanical behavior; stress; strain; phonon; vibrational mode; Raman spectroscopy; tension

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

APA (6^th Edition):

Yashinski , M. S. (2012). Effect of Large Elastic Strains on Phonons in GaP Nanowires. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15148

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Yashinski , Melisa Sue. “Effect of Large Elastic Strains on Phonons in GaP Nanowires.” 2012. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/15148.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Yashinski , Melisa Sue. “Effect of Large Elastic Strains on Phonons in GaP Nanowires.” 2012. Web. 06 Mar 2021.

Vancouver:

Yashinski MS. Effect of Large Elastic Strains on Phonons in GaP Nanowires. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/15148.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Yashinski MS. Effect of Large Elastic Strains on Phonons in GaP Nanowires. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/15148

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

3. Bernard, Matthew Stephen. Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows.

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/22786

► Correctly predicting the interfacial area concentration is vital to the overall accuracy of the two-fluid model because the interfacial area concentration describes the amount of… (more)

▼ Correctly predicting the interfacial area concentration is vital to the overall accuracy of the two-fluid model because the interfacial area concentration describes the amount of surface area that exists between the two-phases, and is therefore directly related to interfacial mass, momentum and energy transfer. The conventional method for specifying the interfacial area concentration in the two-fluid model is through flow regime-based empirical correlations coupled with regime transition criteria. However, a more physically consistent approach to predicting the interfaciala area concentration is through the interfacial area transport equation (IATE), which can address the deficiencies of the flow regime-based approach. Some previous studies have been performed to demonstrate the feasibility of IATE in developmental versions of the nuclear reactor systems analysis code, TRACE. However, a full TRACE version capable of predicting boiling two-phase flows with the IATE has not been established. Therefore, the current work develops a version of TRACE that is capable of predicting boiling two-phase flows using the IATE. The development is carried out in stages. First, a version of TRACE which employs the two-group IATE for adiabatic, vertical upward, air-water conditions is developed. An in-depth assessment on the existing experimental database is performed to select reliable experimental data for code assessment. Then, the implementation is assessed against the qualified air-water two-phase flow experimental data. Good agreement is observed between the experimental data for and the TRACE code with an average error of 9% for all conditions. Following the initial development, one-group IATE models for vertical downward and horizontal two-phase flows are implemented and assessed against qualified data. Finally, IATE models capable of predicting subcooled boiling two-phase flows are implemented. An assessment of the models shows that TRACE is capable of generating interfacial area concentration in subcooled boiling two-phase flows with the IATE and that heat transfer effects dominate the evolution of in these flows. In parallel to developing a TRACE version with the IATE capability, an extensive study is performed to improve the capabilities of the four-sensor conductivity probe. These include improvements in both the signal processing software and processing schemes. Furthermore, experiments are performed in 14 additional test conditions. These test conditions are strategically chosen to establish database in flow conditions where specific bubble interaction mechanisms in the IATE are highlighted. The data established in the experiments are used to further assess and validate the IATE models available in TRACE. Advisors/Committee Members: Seungjin Kim, Dissertation Advisor/Co-Advisor, Seungjin Kim, Committee Chair/Co-Chair, John Harlan Mahaffy, Committee Member, Kostadin Nikolov Ivanov, Committee Member, Francesco Costanzo, Committee Member, Chris Hoxie, Special Member.

Subjects/Keywords: TRACE; ai; interfacial area concentration; interfacial area transport equation; IATE; conductivity probe; two-phase flow; boiling; one-group IATE; two-group IATE

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

APA (6^th Edition):

Bernard, M. S. (2014). Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/22786

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Bernard, Matthew Stephen. “Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows.” 2014. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/22786.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Bernard, Matthew Stephen. “Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows.” 2014. Web. 06 Mar 2021.

Vancouver:

Bernard MS. Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows. [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/22786.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Bernard MS. Implementation of the Interfacial Area Transport Equation in TRACE for Boiling Two-Phase Flows. [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/22786

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

4. Roy, Arjun. Failure-time statistics of a coupled-field damage evolution model via temporal averaging.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16179

► We study the coupling between dynamics at different time-scales during fatigue damage growth with an objective of understanding the factors that lead to large variations… (more)

▼ We study the coupling between dynamics at different time-scales during fatigue damage growth with an objective of understanding the factors that lead to large variations observed in the statistics of life of specimens subject to periodic loading. For this we study a previously developed 1D coupled-field damage evolution model that couples the dynamics at the macroscopic and microscopic scales. We perform Monte-Carlo life-cycle simulations of large ensembles of initial random micro-states with the objective of determining the effect of initial microsturctural uncertainty on the variability of failure-time statistics. We find through our simulations that the spatial evolution of damage is governed by the spatial distribution of the unperturbed steady-state macroscopic strain and that the failure-time distribution of the bar damage failure-time distributions have oscillations that have a period that is half of the forcing period. However, direct numerical simulations of large ensembles for such multi-scale models are expensive, as the time-scales of the macroscopic and microscopic systems are usually very disparate. To overcome this challenge we use the method of averaging to average out the macroscopic dynamics. We first implement the method of averaging on a 1-DOF version of our continuum problem and use it to determine a universal slow time-scale in which the evolution of damage is independent of the forcing amplitude and the parameter that governs the damage evolution rate. This not only helps us to reduce computational time by orders of magnitude, but also helps us to understand the nature of S-N curves for our model. We also implement the method of averaging on a 2-DOF damage evolution model and demonstrate the existence of a first integral for the system and that the damage phase space can be partitioned into regions corresponding to different damage failure modes. We then develop a numerical scheme, based on the method of averaging, that can be used to extend our averaging scheme numerically to higher dimensions. This helps to reduce the computational time required for life-cycle simulations of our continuum model by a large factor and we therefore then use this method to study failure-time statistics. We first use the averaged equations to develop lower dimensional models that capture the evolution of damage occurring in a bar with seeded faults. We then use the averaged equations to derive approximate expressions for the failure time for a brittle bar and use it to demonstrate the importance of the spatial correlation of initial damage on the convergence of failure-times. Next we perform life-cycle simulations for ensembles of initial damage conditions at different forcing frequency to demonstrate a direct correlation between the spatial localization of damage and the relative variability of failure times. Finally, we use semi-analytical techniques to demonstrate a periodic dependence of the median failure-time on the forcing frequency for fatigue of brittle materials. Advisors/Committee Members: Joseph Paul Cusumano, Dissertation Advisor/Co-Advisor, Joseph Paul Cusumano, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Eric M Mockensturm, Committee Member.

Subjects/Keywords: fatigue; continuum damage mechanics; method of averaging; extreme value statistics; failure-time statistics

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

APA (6^th Edition):

Roy, A. (2012). Failure-time statistics of a coupled-field damage evolution model via temporal averaging. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16179

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Roy, Arjun. “Failure-time statistics of a coupled-field damage evolution model via temporal averaging.” 2012. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/16179.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Roy, Arjun. “Failure-time statistics of a coupled-field damage evolution model via temporal averaging.” 2012. Web. 06 Mar 2021.

Vancouver:

Roy A. Failure-time statistics of a coupled-field damage evolution model via temporal averaging. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/16179.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Roy A. Failure-time statistics of a coupled-field damage evolution model via temporal averaging. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/16179

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

5. Nama, Nitesh. MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK.

Degree: 2017, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/13950nxn144

► The lab-on-a-chip concept refers to the quest of integrating numerous functionalities onto a single microchip for applications within medicine and biotechnology. To achieve precise fluid… (more)

▼ The lab-on-a-chip concept refers to the quest of integrating numerous functionalities onto a single microchip for applications within medicine and biotechnology. To achieve precise fluid and particle handling capabilities required for such applications, microacoustofluidics (i.e. the merger of acoustics and microfluidics) has shown great potential. The primary motivation of this dissertation is to revisit the formulation of the governing equations for microacoustofluidics in an fluid-structure interaction (FSI) context to develop a numerical formulation that is transparent with regards to the reference frames as well as the time-scale separation. In this context, we present a generalized Lagrangian formulation by posing our governing equations over a convenient mean configuration that does not coincide with the current configurations. The formulation stems from an explicit separation of time-scales resulting in two subproblems: a first-order problem, formulated in terms of the fluid displacement at the fast scale, and a second-order problem formulated in terms of the Lagrangian flow velocity at the slow time scale. Following a rigorous time-averaging procedure, the second-order problem is shown to be intrinsically steady, and with exact boundary conditions at the oscillating walls. Also, as the second-order problem is solved directly for the Lagrangian velocity, the formulation does not need to employ the notion of Stokes drift, or any associated post-processing, thus facilitating a direct comparison with experiments. Because the first-order problem is formulated in terms of the displacement field, our formulation is directly applicable to more complex fluid-structure interaction problems in microacoustofluidics. We also present a comparison of the generalized Lagrangian formulation with the typically employed Eulerian formulation and highlight the superior numerical performance of our formulation to aid easier comparison with the experimental observations. Next, we describe the fluid and particle motion in acoustically-actuated, confined, leaky systems. The investigated model system is a microchip typically used for biomedical analyses; a liquid-filled polydimethylsiloxane microchannel driven acoustically by inter-digital transducers. Through a combination of quantitative experimental measurements and numerical results, we reveal the full three dimensional motion of the fluids and suspended particles. By varying the size of suspended particles, we capture the two limits for which the particle motion is dominated by the acoustic streaming drag to which it is dominated by the acoustic radiation force. The observed fluid and particle motion is captured numerically without any fitting parameter by a reduced-fluid model based on a thermoviscous, Lagrangian velocity-based formulation. Through a combination of experimental observations and precise numerical boundary conditions, we remove the existing ambiguity in the literature concerning the acoustic streaming direction as well as the critical particle size for which the… Advisors/Committee Members: Francesco Costanzo, Dissertation Advisor/Co-Advisor, Tony Jun Huang, Committee Chair/Co-Chair, Jonathan Pitt, Committee Member, Francesco Costanzo, Committee Member, Peter Butler, Outside Member.

Subjects/Keywords: Microfluidics; Arbitrary Lagrangian Eulerian Method; Acoustofluidics; Surface Acoustic Wave; Finite Element Method; Immersed Finite Element Method; Fluid-Structure Interaction; Acoustic Streaming; Acoustic radiation Force

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

APA (6^th Edition):

Nama, N. (2017). MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/13950nxn144

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Nama, Nitesh. “MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK.” 2017. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/13950nxn144.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Nama, Nitesh. “MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK.” 2017. Web. 06 Mar 2021.

Vancouver:

Nama N. MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK. [Internet] [Thesis]. Penn State University; 2017. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/13950nxn144.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Nama N. MICROACOUSTOFLUIDICS: AN ARBITRARY LAGRANGIAN-EULERIAN FRAMEWORK. [Thesis]. Penn State University; 2017. Available from: https://submit-etda.libraries.psu.edu/catalog/13950nxn144

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

6. Huang, Po-Hsun. SHARP-EDGE-BASED ACOUSTOFLUIDICS.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/7h149p84n

► Over the past few decades, microfluidics has emerged as a powerful tool for a wide variety of applications, from chemical applications, such as monitoring of… (more)

▼ Over the past few decades, microfluidics has emerged as a powerful tool for a wide variety of applications, from chemical applications, such as monitoring of chemical reactions and material synthesis, to biological applications, such as cell differentiation and single-cell analysis. We have also witnessed the rapid advancement of related technologies. Despite the advancement, the adoption of microfluidic devices in daily human life for diagnostic and therapeutic purposes is still very limited, the reason being that to date, only a few powerful fluid manipulation devices have been proposed. This thesis has centered on understanding, designing, and prototyping a new class of acoustofluidic (i.e., the fusion of acoustics and microfluidics) devices to pave the foundation for applications, ranging from biomedical/chemical research to clinical applications. Implementing the acoustic streaming effect induced by oscillating sharp-edge structures in microfluidics, we have developed a series of sharp-edge-based acoustofluidic technologies that are able to control and manipulate fluids and micro-objects. First of all, an acoustofluidic micromixer is developed where rapid and homogeneous mixing of fluid was achieved via the acoustic streaming induced by oscillating sharp-edge structures. The acoustic streaming induced by the oscillation of sharp-edge structures allows two fluids to interchange and thus enhances the mass transport across the channel, greatly improving the mixing efficiency. Our sharp-edge-based acoustofluidic micromixer possesses desirable characteristics, including excellent mixing performance, simplicity, convenient and stable operation, fast mixing speed, and ability to be toggled on-and-off, which makes it a promising candidate for a wide variety of lab-on-a-chip applications. Built directly on the sharp-edge-based acoustofluidic micromixer, a modified sharp-edge-based acoustofluidic micromixer is developed for the mixing of highly-viscous fluid samples. The capability of our sharp-edge-based acoustofluidic micromixer for the mixing of highly-viscous samples is demonstrated by liquefying human sputum samples on-chip, which, to the best of our knowledge, is the first microfluidic sputum liquefaction device, also known as acoustofluidic sputum liquefier. Our sharp-edge-based acoustofluidic sputum liquefier is a promising candidate for incorporation with other on-chip components that will enable the development of a fully integrated, self-contained sputum processing and analysis platform. In addition, our device can possibly be employed for applications that require the processing of highly viscous fluids. By engineering the acoustic streaming patterns generated inside the microfluidic channel, a sharp-edge-based acoustofluidic chemical gradient generator is presented. The generation of concentration gradients of chemical is due to the serial mixing of different solutions. Through the modulation of the driving signals of piezoelectric transducer, our sharp-edge-based acoustofluidic gradient generator can… Advisors/Committee Members: TONY JUN HUANG, Dissertation Advisor/Co-Advisor, Jun Huang, Committee Chair/Co-Chair, Bernhard R Tittmann, Committee Member, Francesco Costanzo, Committee Member, Siyang Zheng, Outside Member, Corina Stefania Drapaca, Committee Member.

Subjects/Keywords: Microfluidics; Acoustofluidics; Acoustic streaming; Micropump; Micromixer; Chemical gradient; Sputum liquefaction

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

APA (6^th Edition):

Huang, P. (2016). SHARP-EDGE-BASED ACOUSTOFLUIDICS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/7h149p84n

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Huang, Po-Hsun. “SHARP-EDGE-BASED ACOUSTOFLUIDICS.” 2016. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/7h149p84n.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Huang, Po-Hsun. “SHARP-EDGE-BASED ACOUSTOFLUIDICS.” 2016. Web. 06 Mar 2021.

Vancouver:

Huang P. SHARP-EDGE-BASED ACOUSTOFLUIDICS. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/7h149p84n.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Huang P. SHARP-EDGE-BASED ACOUSTOFLUIDICS. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/7h149p84n

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

7. Won, Dong Jin. MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT.

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/11516

► Indium can act as a surfactant on the growing GaN surface without being incorporated due to its high vapor pressure at growth temperatures of 900… (more)

▼ Indium can act as a surfactant on the growing GaN surface without being incorporated due to its high vapor pressure at growth temperatures of 900 – 1000 °C. Thus, indium surfactant can modify the growth mode of GaN films by changing surface energy and surface kinetics of adsorbed Ga and N adatoms. In this thesis research, the effect of indium surfactant on Ga-polar and N-polar GaN films grown at 950 °C by MOCVD on various substrates such as Si-face SiC, bulk GaN, Si(111), and C-face SiC was studied to investigate the stress relaxation mechanism, structural, and optical properties of GaN films which were modified by the indium surfactant. The effect of indium surfactant on GaN films grown on SiC was studied first. In the 1.8 m thick Ga-polar GaN films grown on lattice-mismatched Si-face SiC substrates utilizing indium surfactant at 950 °C, inverted hexagonal pyramid surface defects, so-called V-defects which consist of six planes, formed at threading dislocations on the GaN surface, which gave rise to the relaxation of compressive misfit stress in an elastic way. Simultaneously, enhanced surface mobility of Ga and N adatoms with indium surfactant lead to improved 2D growth, which may be contradictory to the formation of surface defects like V-defects. In order to find the driving force for V-defect formation in the presence of indium, a nucleation and growth model was developed, taking into consideration the strain, surface, and dislocation energies modified by indium surfactant. This model found that the V-defect formation can be energetically preferred since indium reduces the surface energy of the plane, which gives rise to the V-defect formation and growth that can overcome the energy barrier at the critical radius of the V-defect. These Ga-polar GaN films were found to be unintentionally doped with Si. Thus, an investigation into the effect of intentional Si doping at a constant TMIn flow rate on GaN films was also performed. Si turned out to be another important factor in the generation of V-defects because Si may be captured at the threading dislocation cores by forming Si – N bonds, acting as a mask to locally prevent GaN growth. This behavior appeared to assist the initiation of the V-defect which enables V-defects to easily grow beyond the critical radius. Thus, introduction of indium surfactant and Si doping was found to be the most favorable conditions for V-defect formation in Ga-polar GaN films grown on Si-face SiC substrates. The nucleation and growth model predicted that V-defects may not form in homoepitaxy because the energy barrier for V-defect formation approaches infinity due to zero misfit stress. When indium surfactant and Si dopant were introduced simultaneously during the homoepitaxial growth, V-defects did not form in 1.8 m thick Ga-polar GaN films grown at 950 °C on bulk GaN that had very low threading dislocation density, as predicted by the nucleation and growth model. Ga-polar GaN films grown on Si(111) substrates using indium surfactant showed that additional tensile… Advisors/Committee Members: Joan Marie Redwing, Dissertation Advisor/Co-Advisor, Joan Marie Redwing, Committee Chair/Co-Chair, Christopher Muhlstein, Committee Member, Elizabeth C Dickey, Committee Member, Francesco Costanzo, Committee Member.

Subjects/Keywords: GaN; AlN; nitrides; MOCVD; Indium surfactant; epitaxy; heteroepitaxy; XRD; PL; AFM; Raman

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

APA (6^th Edition):

Won, D. J. (2011). MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/11516

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Won, Dong Jin. “MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT.” 2011. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/11516.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Won, Dong Jin. “MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT.” 2011. Web. 06 Mar 2021.

Vancouver:

Won DJ. MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT. [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/11516.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Won DJ. MOCVD GROWTH OF GALLIUM NITRIDE WITH INDIUM SURFACTANT. [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/11516

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

8. Worosz, Theodore Stanley. Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/27302

► To fully realize the benefit of the two-group interfacial area transport equation (IATE) as a constitutive model for the interfacial area concentration in the two-fluid… (more)

▼ To fully realize the benefit of the two-group interfacial area transport equation (IATE) as a constitutive model for the interfacial area concentration in the two-fluid model, it is imperative that models be developed to dynamically transition from one-group to two-group flows. With this in mind, the two-group IATE is derived in detail to establish new expansion source terms that correctly account for the effects of intergroup bubble transport. In addition to this theoretical effort, the state-of-the-art four-sensor conductivity probe is used to establish a reliable experimental database of local two-phase flow parameters to characterize one-group to two-group transition flows and to support model development. The experiments are performed in vertical-upward air-water two-phase flow in a 5.08cm pipe. Additionally, the local conductivity probe is improved through systematic studies into: 1) signal “ghosting” electrical interference among probe sensors, 2) sampling frequency sensitivity, 3) measurement duration sensitivity, and 4) probe sensor orientation. Wake-dominated bubble transport characterizes the transition from one-group to two-group flows. Therefore, the necessary intergroup and intragroup wake entrainment source terms that are required for two-group interfacial area transport in transition flows are developed. Furthermore, an approach is developed to initiate the shearing-off source and reduce the one-group interaction mechanisms as an established two-group flow develops. The new interfacial area transport model for one-group to two-group transition flows is evaluated against the experimental database. The model accurately captures the exchange of void fraction and interfacial area concentration between group-I and group-II in transition flows. Overall, the group-I void fraction and interfacial area concentration are predicted within ±6% and ±4%, respectively, of the experimental data. The group-II void fraction and interfacial area concentration are predicted within ±9% and ±11%, respectively, of the experimental data. Advisors/Committee Members: Seungjin Kim, Dissertation Advisor/Co-Advisor, Seungjin Kim, Committee Chair/Co-Chair, Fan Bill B Cheung, Committee Member, Kostadin Nikolov Ivanov, Committee Member, Francesco Costanzo, Committee Member, Kevin Hogan, Special Member.

Subjects/Keywords: two-phase flow; interfacial area concentration; two-group interfacial area transport; multi-sensor conductivity probe; cap-bubbl

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

APA (6^th Edition):

Worosz, T. S. (2015). Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/27302

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Worosz, Theodore Stanley. “Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows.” 2015. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/27302.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Worosz, Theodore Stanley. “Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows.” 2015. Web. 06 Mar 2021.

Vancouver:

Worosz TS. Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/27302.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Worosz TS. Interfacial Area Transport Equation for Bubbly to Cap-bubbly Transition Flows. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/27302

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

9. Kauffman, Justin A. An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method.

Degree: 2018, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/15005jak5378

► Computational simulations contain discretizations of both a physical domain and a mathematical model. In this dissertation, an overset mesh framework is used to discretize the… (more)

▼ Computational simulations contain discretizations of both a physical domain and a mathematical model. In this dissertation, an overset mesh framework is used to discretize the physical domain, and the hybridizable discontinuous Galerkin (HDG) finite element method is used to discretize the mathematical model. It is proposed that using an overset mesh framework for the HDG method enables stable solutions to be computed for complex geometries and dynamic meshes. Overset mesh methods are chosen because they are efficient at decomposing geometrically complex domains. The HDG method was chosen because it provides solutions that are arbitrarily high-order accurate, reduces the size of the global discrete problem, and has the ability to solve elliptic, parabolic, and/or hyperbolic problems with a unified form of discretization. An overset mesh method can utilize an inherent property of the HDG method, the decomposition of the solution into global (face) and local (volume) parts. The global solution exists only on the cell boundaries; while, the local solution exists in the interior of each cell and is decoupled between neighboring cells. This decomposition introduces face-volume coupling in the weak form for degrees of freedom on cell boundaries, which is used as the foundation for the overset communication between subdomains. Ultimately, the goal of this work is to simulate full-scale hydrodynamic and fluid-structure interaction (FSI) problems. To achieve these simulations, the necessary building blocks must first be verified and validated in the overset-HDG framework. The building blocks demonstrated in this dissertation are steady convection-diffusion, linear elasticostatics, and pseudo-compressible Navier-Stokes in both Eulerian and arbitrary Lagrangian-Eulerian frames. Computational simulations are performed to demonstrate the applicability and accuracy of the overset-HDG algorithm. Advisors/Committee Members: Jonathan S Pitt, Dissertation Advisor/Co-Advisor, Jonathan S Pitt, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Corina Stefania Drapaca, Committee Member, James Joseph Brannick, Outside Member, Scott Miller, Special Member.

Subjects/Keywords: Overset Mesh Methods; Hybridizable discontinuous Galerkin; HDG; Finite Element Method; Pseudo-compressibility; Arbitrary Lagrangian-Eulerian; Navier-Stokes; Elasticity

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

APA (6^th Edition):

Kauffman, J. A. (2018). An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/15005jak5378

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kauffman, Justin A. “An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method.” 2018. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/15005jak5378.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kauffman, Justin A. “An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method.” 2018. Web. 06 Mar 2021.

Vancouver:

Kauffman JA. An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method. [Internet] [Thesis]. Penn State University; 2018. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/15005jak5378.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kauffman JA. An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method. [Thesis]. Penn State University; 2018. Available from: https://submit-etda.libraries.psu.edu/catalog/15005jak5378

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

10. Xu, Xiang. Topics on Stability of Complex Fluid Models.

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/12183

► In this thesis, we study analytical problems related to two models in the hydrodynamics of complex fluids. The first is the general Ericksen-Leslie system, which… (more)

Subjects/Keywords: stability analysis; energetic variational approaches; long time behavior; Parodi's relation

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

APA (6^th Edition):

Xu, X. (2011). Topics on Stability of Complex Fluid Models. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/12183

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Xu, Xiang. “Topics on Stability of Complex Fluid Models.” 2011. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/12183.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Xu, Xiang. “Topics on Stability of Complex Fluid Models.” 2011. Web. 06 Mar 2021.

Vancouver:

Xu X. Topics on Stability of Complex Fluid Models. [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/12183.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Xu X. Topics on Stability of Complex Fluid Models. [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/12183

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

11. Aycock, Kenneth Iven. Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/13307kia104

► Inferior vena cava (IVC) filters have been used to mitigate pulmonary embolism (PE) in at-risk patients for nearly half a century. Despite years of innovation,… (more)

▼ Inferior vena cava (IVC) filters have been used to mitigate pulmonary embolism (PE) in at-risk patients for nearly half a century. Despite years of innovation, IVC filter-related complications remain common, including caval perforation, filter embedment, filter fracture, filter migration, persistence or worsening of deep-vein thrombosis due to IVC thrombosis, and recurrence of PE. In this thesis, a computational workflow is developed and demonstrated for simulating IVC filter placement, hemodynamics, and embolus transport and capture in patient-specific models reconstructed from medical image data. Patient-specific IVC geometries are first segmented and reconstructed from clinical computed tomography data. Virtual IVC filter placement is then performed using nonlinear finite element analysis with vein-filter contact modeling and nonlinear constitutive models for the vein tissue and nitinol IVC filter. The blood flow and the transport and capture of emboli are simulated using a coupled computational fluid dynamics / six degree-of-freedom (CFD/6DoF) model that uses an immersed boundary method to resolve the blood flow around the emboli. The embolus-trapping performance of the filter is predicted by systematically varying embolus starting positions, embolus diameters, embolus densities, and IVC orientations in thousands of embolus transport simulations. Simulations reveal that patient-specific variations in the IVC cross-sectional shape cause a non-uniform distribution of vein–filter contact forces among the filter struts (range of 8-26 mN per strut). Patient-specific anatomical features also generate regions of locally high or low wall shear stress (WSS) and affect secondary flow features such as Dean vortices and flow recirculation regions. Non-Newtonian blood effects are found to be significant in the IVC (e.g., up to a 50% difference in WSS between results obtained using a non-Newtonian model compared with using the Newtonian approximation) due to the predominance of low shear rates. Embolus transport simulations predict that embolus trajectories and capture rates for a given filter are sensitive to the IVC morphology, the embolus-to-blood density ratio, and the direction of the gravitational force (i.e., patient orientation). With further development and validation, the computational workflow presented herein may be used to guide IVC filter design, to predict the in vivo performance of IVC filters, and to guide the selection and placement of IVC filters on a patient-specific basis. Simulations could also be used to improve preclinical testing standards such that benchtop experiments better mimic the in vivo environment and performance of IVC filters. Advisors/Committee Members: Keefe B. Manning, Dissertation Advisor/Co-Advisor, Robert L. Campbell, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Michael Krane, Committee Member, Donna H. Korzick, Outside Member, Brent A. Craven, Dissertation Advisor/Co-Advisor, Keefe B. Manning, Committee Chair/Co-Chair.

Subjects/Keywords: IVC filter; nitinol; pulmonary embolism; immersed boundary method; six degrees of freedom; inferior vena cava; computational fluid dynamics; finite element analysis; non-Newtonian; hemorheology; hemodynamics; patient-specific; computational modeling; embolus transport; coupled CFD/6-DOF; fictitious domain method

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

APA (6^th Edition):

Aycock, K. I. (2016). Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/13307kia104

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Aycock, Kenneth Iven. “Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance.” 2016. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/13307kia104.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Aycock, Kenneth Iven. “Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance.” 2016. Web. 06 Mar 2021.

Vancouver:

Aycock KI. Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/13307kia104.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Aycock KI. Towards Patient-Specific Modeling of Inferior Vena Cava Filter Performance. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/13307kia104

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

12. Leonard, Daniel Joseph. Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/24845

► Hydropower is the most proven renewable energy technology, supplying the world with 16% of its electricity. Conventional hydropower generates a vast majority of that percentage.… (more)

▼ Hydropower is the most proven renewable energy technology, supplying the world with 16% of its electricity. Conventional hydropower generates a vast majority of that percentage. Although a mature technology, hydroelectric generation shows great promise for expansion through new dams and plants in developing hydro countries. Moreover, in developed hydro countries, such as the United States, installing generating units in existing dams and the modern refurbishment of existing plants can greatly expand generating capabilities with little to no further impact on the environment. In addition, modern computational technology and fluid dynamics expertise has led to substantial improvements in modern turbine design and performance. Cavitation has always presented a problem in hydroturbines, causing performance breakdown, erosion, damage, vibration, and noise. While modern turbines are usually designed to be cavitation-free at their best efficiency point, due to the variable demand of the energy market it is fairly common to operate at off-design conditions. Here, cavitation and its deleterious effects are unavoidable, and hence, cavitation is a limiting factor on the design and operation of these turbines. Multiphase Computational Fluid Dynamics (CFD) has been used in recent years to model cavitating flow for a large range of problems, including turbomachinery. However, CFD of cavitating flow in hydroturbines is still in its infancy. This dissertation presents steady-periodic Reynolds-averaged Navier-Stokes simulations of a cavitating Francis-class hydroturbine at model and prototype scales. Computational results of the reduced-scale model and full-scale prototype, undergoing performance breakdown, are compared with empirical model data and prototype performance estimations based on standard industry scalings from the model data. Mesh convergence of the simulations is also displayed. Comparisons are made between the scales to display that cavitation performance breakdown can occur more abruptly in the model than the prototype, due to lack of Froude similitude between the two. When severe cavitation occurs, clear differences are observed in vapor content between the scales. A stage-by-stage performance decomposition is conducted to analyze the losses within individual components of each scale of the machine. As cavitation becomes more severe, the losses in the draft tube account for an increasing amount of the total losses in the machine. More losses occur in the model draft tube as cavitation formation in the prototype draft tube is prevented by the larger hydrostatic pressure gradient across the machine. Additionally, unsteady Detached Eddy Simulations of the fully-coupled cavitating hydroturbine are performed for both scales. Both mesh and temporal convergence studies are provided. The temporal and spectral content of fluctuations in torque and pressure are monitored and compared between single-phase, cavitating, model, and prototype cases. A shallow draft tube induced runner imbalance results in… Advisors/Committee Members: Scott Miller, Dissertation Advisor/Co-Advisor, Scott Miller, Committee Chair/Co-Chair, Jules Washington Lindau V, Special Member, Francesco Costanzo, Committee Member, Jonathan S Pitt, Committee Member, John Michael Cimbala, Committee Member, Brent A Craven, Committee Member.

Subjects/Keywords: CFD; Computational Fluid Dynamics; Multiphase; Cavitation; Hydroturbine; RANS; DES; Performance Breakdown; Francis turbine

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

APA (6^th Edition):

Leonard, D. J. (2015). Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/24845

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Leonard, Daniel Joseph. “Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines.” 2015. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/24845.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Leonard, Daniel Joseph. “Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines.” 2015. Web. 06 Mar 2021.

Vancouver:

Leonard DJ. Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/24845.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Leonard DJ. Computation and Analysis of Cavitating Flow in Francis-class Hydraulic Turbines. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/24845

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

13. Sheldon, Jason Paul. A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction.

Degree: 2016, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/27574

► As computational methods have matured and computing power has increased over the years, simulations have grown in complexity by attempting to accurately model both larger… (more)

▼ As computational methods have matured and computing power has increased over the years, simulations have grown in complexity by attempting to accurately model both larger and more involved physical systems. Although the computational demand of these simulations has increased, the required accuracy of the solution has not decreased, resulting in simulations that can become prohibitively computationally expensive. New computational tools need to be developed that both maintain solution accuracy while minimizing the ever increasing computational cost in time and resources. This dissertation presents a novel application of the recently developed hybridizable discontinuous Galerkin (HDG) finite element method to the multi-physics simulation of coupled fluid-structure interaction (FSI) problems. Current applications of the HDG method are reviewed and shown to be limited in scope to single-physics scenarios; however, they do include both solid and fluid problems, which are necessary for FSI modeling. Utilizing these established models, HDG formulations for linear elastostatics, linear elastodynamics, nonlinear elastodynamics, Eulerian Navier-Stokes, and arbitrary Lagrangian-Eulerian Navier-Stokes are derived. The elasticity formulations are all written in a Lagrangian reference frame, with the nonlinear formulation restricted to hyperelastic materials. With these individual solid and fluid formulations, the remaining challenge in FSI modeling is coupling together their disparate mathematics on the fluid-solid interface. In past work (Sheldon, 2012; Sheldon et al., 2014), a continuous Galerkin FSI model with a variety of coupling strategies was implemented, which greatly facilitated the process of creating a novel HDG FSI model. HDG FSI modeling comes with its own unique challenges, however, which are discussed and then addressed by modifications to the established component formulations. The resultant HDG FSI model is then presented. Verification of the component models, through the method of manufactured solutions, is performed and each model is shown to converge at the expected rate. The individual components, along with the complete FSI model, are then numerically validated against benchmark problems proposed by Turek and Hron (Turek and Hron, 2006). The HDG results show increasing accuracy compared to the benchmark’s measured quantities as simulations are refined. Finally, concluding remarks are presented and the future work necessary to turn this HDG FSI model into a production level tool is outlined. Advisors/Committee Members: Jonathan S Pitt, Dissertation Advisor/Co-Advisor, Scott Miller, Dissertation Advisor/Co-Advisor, Jonathan S Pitt, Committee Chair/Co-Chair, Scott Miller, Committee Chair/Co-Chair, Panagiotis Michaleris, Committee Member, Francesco Costanzo, Committee Member, Paris R Vonlockette, Special Member.

Subjects/Keywords: Hybridizable discontinuous Galerkin; Fluid-Structure Interaction; Arbitrary Lagrangian-Eulerian Navier-Stokes; Elastodynamics

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

APA (6^th Edition):

Sheldon, J. P. (2016). A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/27574

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Sheldon, Jason Paul. “A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction.” 2016. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/27574.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Sheldon, Jason Paul. “A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction.” 2016. Web. 06 Mar 2021.

Vancouver:

Sheldon JP. A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction. [Internet] [Thesis]. Penn State University; 2016. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/27574.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Sheldon JP. A Hybridizable Discontinuous Galerkin Method For Modeling Fluid–structure Interaction. [Thesis]. Penn State University; 2016. Available from: https://submit-etda.libraries.psu.edu/catalog/27574

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

14. Tsau, Shih-Horng. ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/7305

► Using a static mesh in a multi-scale simulation, such as welding, requires many fine elements from the start of the analysis. The mesh needs to… (more)

▼ Using a static mesh in a multi-scale simulation, such as welding, requires many fine elements from the start of the analysis. The mesh needs to be fine throughout the entire simulation in both transverse and longitudinal directions to capture high gradients. Isotropic adaptive meshing performs simultaneous coarsening, and refining, in all spatial dimensions. Application of isotropic adaptive meshing allows the use of a coarse mesh as the analysis begins and it refines as needed in all directions during the simulation. However, because of the nature of isotropic refinement, elements need to remain fine in all dimensions even if the gradient is high in only one direction. In this work, an efficient Anisotropic h-Adaptive (abbreviated AH-adaptive) FEA method is developed that performs independent refining and coarsening among all spatial dimensions. Application of the anisotropic h-adaptive meshing allows the use of a coarse mesh as the analysis starts. If there is one direction in which the gradient is much smoother than the others, the mesh coarsens in the corresponding direction, thus reducing the number of DOFs by n^1/2 in 2D analyses, and n^1/3 in 3D analyses. Dependent (also referred to as "constraint") nodes occur when h-adaptive refinement strategy is applied. The DOFs (degrees of freedom) on these dependent nodes must be separated from the original system of algebraic equations. Only the unconstrained (also referred to as "free") DOFs can exist in the real equation system to solve and therefore yield accurate solution fileds. To deal with the dependent DOFs, several methods can be applied for the numerical computations. A comparison between Condensation and Recovery Method, Lagrange Multiplier, and Penalty Method is performed. And the Condensation and Recovery Method is chosen to be applied in the AH-adaptive FEA scheme to maximize the computational efficiency. Highlights from this research include important contributions such as: 1) simplified gradient calculations for each element, 2) nonzero fill-in effects induced by condensing the original algebraic equation systems, 3) moving forced refinements of anticipated high gradients, 4) procedures which assist meshes with neatly coarsening elements to the allowed maximum, and 5) comparisons among possible approaches for the original system equations from a mesh which has constrained nodes. Advisors/Committee Members: Panagiotis Michaleris, Committee Chair/Co-Chair, Ashok D Belegundu, Committee Member, Eric M Mockensturm, Committee Member, Francesco Costanzo, Committee Member.

Subjects/Keywords: nonzeros in tangent matrix; finite element; AH-adaptive; condensation theory; algorithm; large structure; multi-scale; anisotropic h-adaptive; penalty method; Lagrange multiplier

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

APA (6^th Edition):

Tsau, S. (2008). ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/7305

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Tsau, Shih-Horng. “ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES .” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/7305.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Tsau, Shih-Horng. “ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES .” 2008. Web. 06 Mar 2021.

Vancouver:

Tsau S. ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/7305.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Tsau S. ANISOTROPIC H-ADAPTIVE (AH-ADAPTIVE) FINITE ELEMENT SCHEME FOR THREE-DIMENSIONAL MULTI-SCALE ANALYSES . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/7305

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

15. Zhu, Yunrong. ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/8775

► This dissertation is devoted to practical design and theoretical analysis of efficient and robust preconditioners for solving algebraic systems arising from the approximation of partial… (more)

▼ This dissertation is devoted to practical design and theoretical analysis of efficient and robust preconditioners for solving algebraic systems arising from the approximation of partial differential equations, with special emphasis on the problems with strongly discontinuous coefficients. The problems considered here include the standard second order elliptic equations (H(grad) or H¹ equations), as well as the second order elliptic systems given in terms of curl and divergence operators (H(curl) and H(div) systems). In regard to the H¹ equations with jump coefficients, we study both the multilevel and domain decomposition preconditioners. We analyze the eigenvalue distribution of the preconditioned systems, and prove that only a small number of eigenvalues may deteriorate with respect to coefficients and mesh size. We show that the other eigenvalues are bounded uniformly with respect to the coefficients of the PDE and bounded poly-logarithmically with respect to mesh size. As a result, the asymptotic convergence rate of the PCG algorithms is uniform with respect to the coefficients, and nearly uniform (up to a logarithmic factor) with respect to the mesh size. Various numerical experiments justify the theoretical results. For H(curl) and H(div) systems, we give a comprehensive analysis of auxiliary space preconditioners, which rely on regular decompositions. Through such constructions, these preconditioners reduce H(curl) and H(div) systems to the solution of several H(grad) equations, which are amenable by standard algebraic multigrid (AMG) techniques. We also develop a preconditioner for H(curl) systems with jump coefficients. We show that the condition number of the preconditioned system is uniformly bounded with respect to coefficients and mesh size. Another class of preconditioners that we propose are the compatible AMG preconditioners for H(curl) and H(div) systems. This approach makes use of a compatible discretization framework. We reformulate the discrete systems into equivalent 2-by-2 block systems based on discrete Hodge decompositions on co-chains, and then construct the AMG preconditioners for the 2-by-2 block systems. As an important application, we present the augmented Lagrangian method for solving mixed formulations of elliptic boundary value problems, which reduces a saddle point problem to a nearly singular H(div) system. Advisors/Committee Members: Jinchao Xu, Committee Chair/Co-Chair, Victor Nistor, Committee Member, Francesco Costanzo, Committee Member, Ludmil Tomov Zikatanov, Committee Member, Anna L Mazzucato, Committee Member.

Subjects/Keywords: Jump Coefficients; Multigrid; BPX preconditioner; Domain Decomposition; Condition Number

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

APA (6^th Edition):

Zhu, Y. (2008). ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/8775

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhu, Yunrong. “ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS.” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/8775.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhu, Yunrong. “ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS.” 2008. Web. 06 Mar 2021.

Vancouver:

Zhu Y. ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/8775.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhu Y. ROBUST PRECONDITIONERS FOR H(grad), H(curl) AND H(div) SYSTEMS WITH STRONGLY DISCONTINUOUS COEFFICIENTS. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/8775

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

16. Qin, Xiaoliang. THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/9205

► Two sets of stabilized, Galerkin finite element formulations for modeling elasto-visco-plastic material response of quasi-steady state processes in Eulerian frames are presented. One set is… (more)

▼ Two sets of stabilized, Galerkin finite element formulations for modeling elasto-visco-plastic material response of quasi-steady state processes in Eulerian frames are presented. One set is based on the rate equilibrium equation, and the other set is based on the true equilibrium equation. The rate equilibrium formulation couples the velocity , stress deformation gradient and internal variable together. While, the true equilibrium formulation solves the velocity, deformation gradient, viscoplastic part of deformation gradient and internal variable simultaneously. The streamline upwind Petrov-Galerkin (SUPG) method is introduced to eliminate spurious oscillations which may be caused by the convection of stress, deformation gradient, viscoplastic deformation gradient and internal variable evolution. A progressively stiffening solution strategy is proposed to improve the convergence of the Newton-Raphson solution procedure. These formulations have been implemented in a 4 node quadrilateral element. Three numerical examples (radial flow, strip drawing and gas metal arc welding) have been modeled to verify the accuracy of these Eulerian methods. A coupled 2-dimensional Eulerian thermo-elasto-visco-plastic model has been developed for modeling the Friction Stir Welding process. First, a coupled thermo-visco-plastic analysis is performed to determine the temperature distribution in the full domain and the incompressible material flow around the spinning tool. Next, an elasto-visco-plastic analysis based on the true equilibrium is performed outside the visco-plastic region to comput the residual stress. Both frictional heat and plastic deformation heat generation are considered in the model. Furthermore, this is the only known model computing residual stress accounting for plasticity caused by both thermal expansion and mechanical deformation due to material spinning. The computed residual stress is verified by comparing to experimentally measured data. Advisors/Committee Members: Panagiotis Michaleris, Dissertation Advisor/Co-Advisor, Panagiotis Michaleris, Committee Chair/Co-Chair, Ashok D Belegundu, Committee Member, Francesco Costanzo, Committee Member, Eric M Mockensturm, Committee Member.

Subjects/Keywords: Coupled thermo-mechanical; Friction Stir Welding

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

APA (6^th Edition):

Qin, X. (2008). THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/9205

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Qin, Xiaoliang. “THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME .” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/9205.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Qin, Xiaoliang. “THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME .” 2008. Web. 06 Mar 2021.

Vancouver:

Qin X. THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/9205.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Qin X. THERMO-ELASTO-VISCO-PLASTIC MODELLING OF FRICTION STIR WELDING IN AN EULERIAN REFERENCE FRAME . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/9205

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

17. Kumar, Chandan. MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS.

Degree: 2009, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/9743

► Semiconductor quantum dots offer possibilities of novel electronic, optoelectronic and computing devices. Epitaxial self-assembled quantum dots (SAQDs) are 3D nanostructures or nanocrystals formed as a… (more)

▼ Semiconductor quantum dots offer possibilities of novel electronic, optoelectronic and computing devices. Epitaxial self-assembled quantum dots (SAQDs) are 3D nanostructures or nanocrystals formed as a result of growth of single crystal film on a single crystal substrate, such that there is a lattice mismatch between the film and the substrate. The growing film acquires the lattice structure and orientation of the substrate. After an initial layer-by-layer growth, a transition from 2D growth to 3D growth takes place. The growth mode resulting in the formation of SAQDs is referred to as the Stranski-Krastanow (SK) growth mode. This growth begins with morphological perturbations on the surface of the strained film, where the strain results from the lattice mismatch between the film and the substrate. Typical, among others, semiconductor quantum dots grown on semiconductor substrates include SiGe on Si, InAs on GaAs and PbSe on PbEuTe. The self-assembly of quantum dots poses a major challenge of controlling the fluctuations in size and shape of the quantum dots, and spacings between the quantum dots. Many potential devices either need a periodic array of quantum dots with uniform sizes or require quantum dots to be placed at precise locations. Self-assembly of quantum dots is the most preferable method to produce large number of quantum dots in an easy way. However, self-assembly is a stochastic process and results in an array of quantum dots with somewhat non-uniform sizes and spatial distribution. Better control of self-assembly is desirable for potential device applications of SAQDs. Techniques, such as substrate patterning or growing multiple layers of quantum dots have been used to control the size and spatial distribution of SAQDs. In an endeavor to better understand the basic mechanism of formation and ordering of SAQDs, this work is aimed at improving existing continuum models and using various statistical tools to probe the morphology of quantum dots and their ordering phenomenon in self-assembly, and to evaluate and understand a case of directed self-assembly. As a consequence it is necessary to develop tools that can be used to predict and quantify the morphology and order of SAQDs with greater accuracy. Various parameters that characterize the formation, morphology and order of SAQDs are identified and results are presented to depict the effect of these parameters on SAQD formation and ordering. Additionally, the results of this work are meant to inform future experiments and numerical models, and aid in developing more advanced and accurate models that can both help understand and predict the trends in SAQD formation. In particular, in this work, the formation, morphology and ordering of quantum dots formed as a result of self-assembly and thermal-field directed self-assembly have been studied in detail, and models have been developed for quantitative assessment using parameters that can control order and morphology in SAQDs. All calculations are performed for Ge dots grown on a Si substrate. The… Advisors/Committee Members: Lawrence H Friedman, Dissertation Advisor/Co-Advisor, Lawrence H Friedman, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Joseph Paul Cusumano, Committee Member, Kristen Ann Fichthorn, Committee Member.

Subjects/Keywords: Thermal Field Directed Self-Assembly; Multilayer; Spectral Analysis; Surface Diffusion; Stochastic; Self-assembly; Quantum Dot; Elastic Heterogeneity

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

APA (6^th Edition):

Kumar, C. (2009). MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/9743

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kumar, Chandan. “MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS.” 2009. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/9743.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kumar, Chandan. “MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS.” 2009. Web. 06 Mar 2021.

Vancouver:

Kumar C. MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS. [Internet] [Thesis]. Penn State University; 2009. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/9743.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kumar C. MODELING AND CONTROLLING NANAOSCALE SELF-ASSEMBLY OF EPITAXIAL QUANTUM DOTS. [Thesis]. Penn State University; 2009. Available from: https://submit-etda.libraries.psu.edu/catalog/9743

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

18. Higley, Michael. Stochastic and Deterministic Processes in Fragmentation and Sedimentation.

Degree: 2010, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/10621

► In this work we present results of analysis, experiment and simulation of two phenomena involving stochastic and deterministic aspects. In the first case we present… (more)

▼ In this work we present results of analysis, experiment and simulation of two phenomena involving stochastic and deterministic aspects. In the first case we present a modeling framework for 1D fragmentation in brittle rods, in which the distribution of fragments is written explicitly in terms of the probability of breaks along the length of the rod. This work is motivated by the experimental observation of several preferred lengths in the fragment distribution of shattered brittle rods after dynamic buckling. Our approach allows for non-constant spatial breaking probabilities, which can lead to preferred fragment sizes. The resulting relation is shown to qualitatively match experimentally observed fragment distributions, as well as some other commonly reported distributions such as a power law with a cutoff. We also present experimental observations of the trajectories and average velocities of solid spheres falling through a curtain of rising bubbles in water. For the quiescent case (no bubbles), the Reynolds numbers are on the order of 1,000, and the average terminal velocity is determined by the form (inertial) drag. The main effect of the introduction of bubbles is to slow down the spheres. In some regimes (smaller or lighter spheres), there is an added random lateral motion to the sphere paths. In this way, a solid sphere sinking in a bubbly fluid and a solid sphere falling through a crowded bed of rigid obstacles (in air) share two common traits: the settling speed is slowed by the obstructions, and the sphere exhibits random lateral motion. We present a mathematical model which begins as an adaptation of Galton's board to the sedimenting sphere. This allows us to introduce various physical effects of the bubbly fluid, and test their importance, particularly that of bubble collisions. Comparison is made with experimental results. Advisors/Committee Members: Andrew Leonard Belmonte, Dissertation Advisor/Co-Advisor, Andrew Leonard Belmonte, Committee Chair/Co-Chair, Qiang Du, Committee Member, Diane Marie Henderson, Committee Member, Francesco Costanzo, Committee Member.

Subjects/Keywords: Galton board; fragment size; settling speed

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

APA (6^th Edition):

Higley, M. (2010). Stochastic and Deterministic Processes in Fragmentation and Sedimentation. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/10621

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Higley, Michael. “Stochastic and Deterministic Processes in Fragmentation and Sedimentation.” 2010. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/10621.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Higley, Michael. “Stochastic and Deterministic Processes in Fragmentation and Sedimentation.” 2010. Web. 06 Mar 2021.

Vancouver:

Higley M. Stochastic and Deterministic Processes in Fragmentation and Sedimentation. [Internet] [Thesis]. Penn State University; 2010. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/10621.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Higley M. Stochastic and Deterministic Processes in Fragmentation and Sedimentation. [Thesis]. Penn State University; 2010. Available from: https://submit-etda.libraries.psu.edu/catalog/10621

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

19. Evans, Brian. Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications .

Degree: 2010, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/10610

► Understanding of the processes that cause nozzle throat erosion and developing methods for mitigation of erosion rate can allow higher operating pressures for advanced rocket… (more)

▼ Understanding of the processes that cause nozzle throat erosion and developing methods for mitigation of erosion rate can allow higher operating pressures for advanced rocket motors. However, erosion of the nozzle throat region, which is a strong function of operating pressure, must be controlled to realize the performance gains of higher operating pressures. The objective of this work was the study the nozzle erosion rates at a broad range of pressures from 7 to 34.5 MPa (1,000 to 5,000 psia) using two different rocket motors. The first is an instrumented solid-propellant motor (ISPM), which uses two baseline solid propellants; one is a non-metallized propellant called Propellant S and the other is a metallized propellant called Propellant M. The second test rig is a non-metallized solid-propellant rocket motor simulator (RMS). The RMS is a gas rocket with the ability to vary the combustion-product species composition by systematically varying the flow rates of gaseous reactants. Several reactant mixtures were utilized in the study to determine the relative importance of different oxidizing species (such as H2O, OH, and CO2). Both test rigs are equipped with a windowed nozzle section for real-time X-ray radiography diagnostics of the instantaneous throat variations for deducing the instantaneous erosion rates. The nozzle test section for both motors can also incorporate a nozzle boundary-layer control system (NBLCS) as a means of nozzle erosion mitigation. The effectiveness of the NBLCS at preventing nozzle throat erosion was demonstrated for both the RMS and the ISPM motors at chamber pressures up to 34 MPa (4930 psia). All tests conducted with the NBLCS showed signs of coning of the propellant surface, leading to increased mass burning rate and resultant chamber pressure. Two correlations were developed for the nozzle erosion rates from solid propellant testing, one for metallized propellant and one for non-metallized propellants. The non-metallized propellant correlation also incorporates the RMS data, accounting for swirling flow of the products in the RMS combustor. These correlations are useful for rocket nozzle designs. The correlation for non-metallized propellant and RMS firings was developed in terms of the effective oxidizer mass fraction and effective Reynolds number. The results calculated from this correlation were compared with measured erosion rate data within ±15% or 0.05 mm/s (2 mils/s). For metallized propellant, the nozzle erosion rate was found to be relatively independent of the concentration of oxidizing species due to the diffusion-controlled process and the partial surface coverage by the liquid Al/Al2O3 layer. The nozzle erosion rate was also found to be lower than those of non-metallized propellant cases. Agreement between predicted and measured erosion rates was found to be within ±20% or 0.04 mm/s (2 mils/s). Advisors/Committee Members: Kenneth K Kuo, Dissertation Advisor/Co-Advisor, Kenneth K Kuo, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Vigor Yang, Committee Member, Richard A Yetter, Committee Member.

Subjects/Keywords: Carbon/Carbon Composites; Erosion Mitigation; Solid Propellant; Nozzle Erosion; Graphite; Rocket Motor Simulator

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

APA (6^th Edition):

Evans, B. (2010). Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/10610

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Evans, Brian. “Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications .” 2010. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/10610.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Evans, Brian. “Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications .” 2010. Web. 06 Mar 2021.

Vancouver:

Evans B. Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications . [Internet] [Thesis]. Penn State University; 2010. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/10610.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Evans B. Nozzle Erosion Characterization and Minimization for High-Pressure Rocket Motor Applications . [Thesis]. Penn State University; 2010. Available from: https://submit-etda.libraries.psu.edu/catalog/10610

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

20. Gorb, Yuliya. Asymptotic Analysis of Effective Properties of Highly Concentrated Composites.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/7155

► The modeling and design of composite materials, which are at the forefront of modern technology, raises fundamental questions of physics, materials science, and mathematics. Many… (more)

Subjects/Keywords: effective properties; high contrast composites; homogenization; asymptotics; discrete network; error estimate; variational bounds; Poiseuille flow

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

APA (6^th Edition):

Gorb, Y. (2008). Asymptotic Analysis of Effective Properties of Highly Concentrated Composites. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/7155

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gorb, Yuliya. “Asymptotic Analysis of Effective Properties of Highly Concentrated Composites.” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/7155.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gorb, Yuliya. “Asymptotic Analysis of Effective Properties of Highly Concentrated Composites.” 2008. Web. 06 Mar 2021.

Vancouver:

Gorb Y. Asymptotic Analysis of Effective Properties of Highly Concentrated Composites. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/7155.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gorb Y. Asymptotic Analysis of Effective Properties of Highly Concentrated Composites. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/7155

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

21. Ghosh, Sudip Kumar. Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/6489

► The process of deglutition includes a series of coordinated neuro-muscular interactions that produce bolus transport and mixing along the human gastrointestinal tract. In this thesis,… (more)

▼ The process of deglutition includes a series of coordinated neuro-muscular interactions that produce bolus transport and mixing along the human gastrointestinal tract. In this thesis, we use a combination of mathematical modeling and physiological data analysis to study the mechanics and macrophysiology underlying antegrade and retrograde bolus transport through the esophagus and the esophago-gastric segment (EGS). Specifically, we analyze normal and abnormal antegrade transport (a) through the esophageal body, (b) across the EGS associated with swallowing, and (c) EGS opening and retrograde flow of gastric fluid associated with gastro-esophageal reflux. The manometrically measured pressure wave, which is associated with peristaltic muscle contraction in the esophagus, consistently displays a trough called the transition zone (TZ) in the neighborhood of the aortic arch. A previous computer model study suggested that the TZ is associated with distinct upper and lower contraction waves that must be coordinated spatially and temporally for successful bolus transport. Through a study of concurrent high resolution manometry and fluoroscopy, we demonstrate that the existence of two distinct contraction waves above and below the esophageal TZ, with a well-defined jump between them, comprises normal neuromuscular physiology. The space-time structure of pressure surrounding the jump shows that the TZ is a region of segmental contraction. In a patient group with higher bolus retention (2.18 ml vs. 0.20 ml), the separation between the two contraction waves was nearly twice as large as normal controls (6.00 cm vs. 3.32 cm), with significantly weaker muscle squeeze pressure in the TZ. We conclude that pathological bolus retention in the aortic arch region of the esophagus is related to an adverse modulation of the neurophysiology that controls the coordination between upper and lower esophageal contraction waves, resulting in inefficient bolus transport. Next, we studied the mechanics of esophageal emptying from a "distal bolus cavity" across the hiatal canal of the EGS to the stomach in normal subjects, and its modulation after fundoplication. Temporal changes in geometry of the distal bolus cavity and hiatal canal and cavity driving pressure were quantified. These data were combined with mathematical models of esophageal emptying and muscle tension driving trans-hiatal flow. All esophageal emptying events post fundoplication were incomplete (51% retention). Whereas there was no significant difference in the period of emptying between controls and patients, average emptying rates were 40% lower in the post-fundoplication group. The mathematical model predicted three distinct phases during esophageal emptying. A rapid increase in muscle tone and driving pressure forced normal hiatal opening. In the post-fundoplication group, a severe impairment of cavity muscle tone resulted in causing deficient hiatal opening and flow and consistent bolus retention. In the final phase of our study, we developed a solid-fluid interaction model… Advisors/Committee Members: James Gordon Brasseur, Committee Chair/Co-Chair, Peter J Kahrilas, Committee Member, Francesco Costanzo, Committee Member, James S Ultman, Committee Member, Richard C Benson, Committee Member.

Subjects/Keywords: fundoplication surgery; esophageal transition zone; acid reflux disease; hiatal hernia; mathematical modeling; fluid-structure interaction; muscle mechanics; lubrication theory

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

APA (6^th Edition):

Ghosh, S. K. (2008). Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/6489

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ghosh, Sudip Kumar. “Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter .” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/6489.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ghosh, Sudip Kumar. “Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter .” 2008. Web. 06 Mar 2021.

Vancouver:

Ghosh SK. Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/6489.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ghosh SK. Modeling, Mechanics and Physiology of the Esophagus and Lower Sphincter . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/6489

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

22. Li, Qiang. Coupled Field Damage Structural Dynamics.

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/7021

► This work aims to develop a class of coupled field, microstructural/macrostructural (damage/structural) models that can be used to study the dynamics of damage evolution. Since… (more)

▼ This work aims to develop a class of coupled field, microstructural/macrostructural (damage/structural) models that can be used to study the dynamics of damage evolution. Since the phenomena of failure and fracture span several spatial scales, from atomic to macro scales, and is very complex, our intention is to emphasize the development of a coupled field model with the simplest possible form while including key features of the dynamics. More specifically, we will use our model to study the relationship between initial microstructural damage state uncertainty and dynamic variability in both space and time domains. We will also examine fundamental properties of damage dynamics, such as the dimensionality over time, and the importance of slow flow dynamics. To develop our coupled field damage dynamics model, we define our damage variable and relate it to material properties. We also consider the existence and forms of generalized forces which are work conjugate to the damage variable. The damage field variable we consider represents the microstructural state, and is not limited to a single or several macro cracks. It is natural, therefore, to adopt the methodology and concepts of continuum damage mechanics to aid in defining our damage variable. Then the coupled field differential equations are obtained by extending the application of Hamilton's principle to materials with microstructure. We incorporate the most important observations in the field of fatigue, such as the existence of a fatigue threshold and sensitivity to initial microstructural state. We also extend the concept of the Griffith energy release rate to the problem with generalized damage, and show that our model is a generalization of a Paris-type damage evolution law. Advisors/Committee Members: Joseph Paul Cusumano, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Leonid V Berlyand, Committee Member, Lawrence H Friedman, Committee Member.

Subjects/Keywords: Continuum Damage Model; Structural Dynamics; Weibull Distribution

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

APA (6^th Edition):

Li, Q. (2008). Coupled Field Damage Structural Dynamics. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/7021

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Li, Qiang. “Coupled Field Damage Structural Dynamics.” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/7021.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Li, Qiang. “Coupled Field Damage Structural Dynamics.” 2008. Web. 06 Mar 2021.

Vancouver:

Li Q. Coupled Field Damage Structural Dynamics. [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/7021.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Li Q. Coupled Field Damage Structural Dynamics. [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/7021

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

23. Shan, Ying. Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications .

Degree: 2008, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/7258

► Flexible matrix composites (FMCs) utilize the high elongation capability of elastomers such as polyurethane to withstand large strains in the direction transverse to the fiber… (more)

▼ Flexible matrix composites (FMCs) utilize the high elongation capability of elastomers such as polyurethane to withstand large strains in the direction transverse to the fiber reinforcement while retaining strength and stiffness in the longitudinal direction. FMCs are highly anisotropic and can therefore be tailored to achieve distinctive mechanical characteristics that are difficult to obtain using conventional rigid matrix composites. In the current study, the potential of using an FMC to construct a flexurally-soft, torsionally-stiff driveshaft is examined. The FMC selected for the current investigation is a carbon fiber/polyurethane matrix material system. Both quasi-static and dynamic tests have been performed to characterize the properties of the FMC material. By modeling viscoelastic FMC lamina properties with a fractional derivative approach, a novel damping model that accounts for the frequency and temperature dependence of the FMC material is developed. This is the first time fractional derivative model has been applied to a fiber composite. Good agreement between the damping model and experimental data for angle-ply tubes was obtained. Based on the validated damping model, a self-heating model to predict the temperature increase caused by internal damping of a FMC shaft under misaligned rotation is also proposed. A laboratory-scale, misaligned FMC shaft rotation test stand was built to validate the proposed model. Good agreement is shown between the self-heating model predictions and experiment results. This model can be valuable in the selection of constituent materials for FMCs and also in the design of FMC shafts. Preliminary fatigue test results show that FMC materials have potentially good fatigue performance in shaft applications. Advisors/Committee Members: Charles E Bakis, Committee Chair/Co-Chair, Francesco Costanzo, Committee Member, Clifford Jesse Lissenden Iii, Committee Member, Edward C Smith, Committee Member, Kon Well Wang, Committee Member.

Subjects/Keywords: self heating; damping; driveshaft; composites; flexible matrix; thermomechanical

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

APA (6^th Edition):

Shan, Y. (2008). Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/7258

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Shan, Ying. “Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications .” 2008. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/7258.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Shan, Ying. “Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications .” 2008. Web. 06 Mar 2021.

Vancouver:

Shan Y. Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications . [Internet] [Thesis]. Penn State University; 2008. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/7258.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Shan Y. Flexible Matrix Composites: Dynamic Characterization, Modeling, and Potential for Driveshaft Applications . [Thesis]. Penn State University; 2008. Available from: https://submit-etda.libraries.psu.edu/catalog/7258

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

24. John, Joby. Inter-Trial Dynamics In Goal-Oriented Tasks.

Degree: 2009, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/10094

► Human beings can perform a variety of skilled tasks repeatedly and reliably. However, the details of joint trajectories and force production reveal considerable variability from… (more)

▼ Human beings can perform a variety of skilled tasks repeatedly and reliably. However, the details of joint trajectories and force production reveal considerable variability from one trial to the next. In this thesis we intend to understand the different factors that affect goal-level variability, a common measure of performance, in repeated trials of skilled tasks. Body-level variability has a significant effect on goal-level variability but it turns out that the body-level variability is just one of the factors; there are other passive and active factors that affect performance. We develop a novel theoretical framework to model the trial-to-trial dynamics arising in repeated trials. This approach, at its core, depends on the idea of a goal function: a mathematical definition of a task in terms of the subject's morphology, the physics of the environment, and the requirements of the task. This goal function, by definition must evaluate to zero for perfect performance. The set of possible body-states that satisfy this relation often has the structure of a goal equivalent manifold (GEM) on which the movement system attempts to converge while trying to achieve the goal. Our models help us analyze the ensuing dynamics and also demonstrates how the various factors like stability, noise and passive sensitivity interact with each other to produce performance. Using our approach we are able to develop data-analysis techniques that assess the stability of the inter-trial control process involved. Also, we are able to reconstruct the time-series of the controller action required to converge on the solution manifold and this sheds light on the structure of performance variability. To test some of the predictions of our model we develop a virtual-reality shuffleboard game. Based on our theory we predict the scaling of goal-level performance with respect to the passive sensitivity properties along the GEM. Using the understanding gained from our model, we also hypothesize that inter-trial dynamics is significantly more stable in a direction normal to the GEM while in the tangential direction it is weakly stable and that fluctuations in these directions are more uncorrelated (less persistent) and more persistent respectively. These hypotheses are tested and established to be true using the data-analysis methods we developed applied to the shuffleboard experiment. The theoretical framework developed in this work can be readily adapted to quantitatively characterize performance in a variety of skilled human tasks. We hope that the data analysis methods developed in this work can be used for movement analysis to distinguish healthy and pathological subjects and also to develop better training and rehabilitation techniques for athletes and people with various movement disorders. Advisors/Committee Members: Joseph Paul Cusumano, Dissertation Advisor/Co-Advisor, Joseph Paul Cusumano, Committee Chair/Co-Chair, Karl Maxim Newell, Committee Member, Francesco Costanzo, Committee Member, Gary L Gray, Committee Member, Christopher Rahn, Committee Member.

Subjects/Keywords: Variability in human movement; Performance; Inter-Trial Dynamics; Goal Equivalent Manifolds; Shuffleboard Experiment

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

APA (6^th Edition):

John, J. (2009). Inter-Trial Dynamics In Goal-Oriented Tasks. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/10094

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

John, Joby. “Inter-Trial Dynamics In Goal-Oriented Tasks.” 2009. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/10094.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

John, Joby. “Inter-Trial Dynamics In Goal-Oriented Tasks.” 2009. Web. 06 Mar 2021.

Vancouver:

John J. Inter-Trial Dynamics In Goal-Oriented Tasks. [Internet] [Thesis]. Penn State University; 2009. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/10094.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

John J. Inter-Trial Dynamics In Goal-Oriented Tasks. [Thesis]. Penn State University; 2009. Available from: https://submit-etda.libraries.psu.edu/catalog/10094

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

25. Kim, Eunhye. Investigation of conical bit rotation in full scale cutting tests .

Degree: 2010, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/11106

► Conical bits are very common in the excavation of soft to medium rock in many mining and construction applications and are used on machines such… (more)

▼ Conical bits are very common in the excavation of soft to medium rock in many mining and construction applications and are used on machines such as roadheaders, continuous miners, drum shearers, and road milling machines. Rotation of the conical bits in its block can extend bit life through a process of even wear on the tip that allows the bit to maintain its tip shape and work more efficiently for an extended period of time. Frequently, this fact does not hold true in actual conical bit application. Grinding on one side of the bit, breaking the bit tip, and severe irregular deformations of conical bits are found when inspecting bits on the cutterhead of mechanical excavators. Strikingly, little is known about causations of bit rotation. Reliable measurement of bit rotation has not been made prior to this study. Therefore the effectiveness of bit rotation and its impact on bit life has been in doubt. To investigate the conical bit rotation phenomenon and parameters affecting this process, a new device was designed and fabricated to measure rotation of a bit in bit holder. For a given conical pick, the main controlling parameters for bit rotation are considered to be skew angle, cut spacing, depth of penetration, and travel speed. To measure the impact of these parameters on bit rotation, full-scale cutting tests were performed at the Kennametal rock cutting lab in Latrobe, PA. This includes linear and rotary cutting tests with single and multiple bits to examine the rotation mechanism of conical bits. Linear cutting tests involve full scale cutting of rock samples along preset lines to measure normal, drag, and side forces and bit rotation while changing the cutting geometry (including skew angle, spacing, and depth of cut). A skew plate was used to change the skew angle for testing. Two different bits, AM-470 from the mining tools and RZ-24 pick from the construction tools were selected for testing. Results of the linear cutting test showed no systematic bit rotation. Some sporadic rotation on the RZ-24 conical tool was primarily due to the contact of the bit body with the ridges formed at higher spacing, something that should be prevented in operational conditions. As such, bit rotation did not show any trends with the primary cutting geometry parameters. A series of analytical and numerical solutions were performed to evaluate the configuration of forces at the bit tip that can cause bit rotation under various loading conditions. This analysis focused on calculation of the required lateral forces for rotation of the bit under certain axial loading of the bit which causes friction between bit shoulder and bit block. This friction prevents bit rotation. The results of the analysis supported the linear cutting test results and observations. Subsequently, rotary cutting tests on a drum laced with a single bit were performed. And bit rotation was measured using the instrumented bits at different skew angles, cutting geometry, and cutting speeds. The results of rotary cutting test show that limited bit rotation occurs… Advisors/Committee Members: Jamal Rostami, Dissertation Advisor/Co-Advisor, Jamal Rostami, Committee Chair/Co-Chair, R Larry Grayson, Committee Member, Derek Elsworth, Committee Member, Francesco Costanzo, Committee Member, Antonio Nieto, Committee Member, Yaw D Yeboah, Committee Member.

Subjects/Keywords: Finite Element Analysis; Full scale cutting test; Rock fragmentation; Conical bit rotation

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

APA (6^th Edition):

Kim, E. (2010). Investigation of conical bit rotation in full scale cutting tests . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/11106

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kim, Eunhye. “Investigation of conical bit rotation in full scale cutting tests .” 2010. Thesis, Penn State University. Accessed March 06, 2021. https://submit-etda.libraries.psu.edu/catalog/11106.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kim, Eunhye. “Investigation of conical bit rotation in full scale cutting tests .” 2010. Web. 06 Mar 2021.

Vancouver:

Kim E. Investigation of conical bit rotation in full scale cutting tests . [Internet] [Thesis]. Penn State University; 2010. [cited 2021 Mar 06]. Available from: https://submit-etda.libraries.psu.edu/catalog/11106.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kim E. Investigation of conical bit rotation in full scale cutting tests . [Thesis]. Penn State University; 2010. Available from: https://submit-etda.libraries.psu.edu/catalog/11106

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Open Access Theses and Dissertations