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Texas A&M University
1.
Zhang, Bingsheng.
On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations.
Degree: PhD, Mathematics, 2016, Texas A&M University
URL: http://hdl.handle.net/1969.1/157862 
► We study the global attractor for the solutions of the incompressible Navier-Stokes equations (NSE) equipped with appropriate boundary conditions. A challenge in the cases when…
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▼ We study the global attractor for the solutions of the incompressible Navier-Stokes equations (NSE) equipped with appropriate boundary conditions.
A challenge in the cases when zero is not in the global attractor is to find sharp lower bound on the energy. A related challenging problem is to show that zero is in the attractor if and only if the external force is zero. We show that if zero were in the global attractor, then all its elements, as well as the external force, must be smooth functions. By exploring a particular family of function classes, we show that the set of nonzero external forces for which zero could be in the global attractor is meagre (of the first Baire category in a Fréchet topology).
The weak global attractor of three dimensional Navier-Stokes equations is a complex geometric object. An interesting challenging question is to measure its complexity. Invoking the fact that topology on the weak global attractor can be metrizable, we use a physically reasonable metric function to obtain explicit estimate for the Kolmogorov e-entropy of the weak global attractor in terms of the physical parameter associated with the fluid flow.
We also study the existence of the nonstationary solutions in the global attractor of the space periodic two dimensional NSE which have constant energy and enstropy per unit mass for all time. A subclass of such solutions whose geometric structures have a supplementary stability property is defined and explored. We prove that the wave vectors of the active mode of this subclass must satisfy a finite Galerkin system. The nonexistence of solutions in this subclass is proved for the particular case when the external force has a special property.
Advisors/Committee Members: Foias, Ciprian (advisor), Chen, Goong (committee member), Panetta, Lee (committee member), Titi, Edriss S. (committee member).
Subjects/Keywords: Navier-Stokes equations; Gevrey class; Kolmogorov forcing; Global attractor; Ghost solutions; Kolmogorov entropy
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APA (6th Edition):
Zhang, B. (2016). On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/157862
Chicago Manual of Style (16th Edition):
Zhang, Bingsheng. “On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations.” 2016. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/157862.
MLA Handbook (7th Edition):
Zhang, Bingsheng. “On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations.” 2016. Web. 04 Mar 2021.
Vancouver:
Zhang B. On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/157862.
Council of Science Editors:
Zhang B. On the Solutions in the Global Attractor of the Incompressible Navier-Stokes Equations. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/157862
Texas A&M University
2.
Tian, Jing.
Study of Nonlinear Analysis and Chaos in Vibrations and Fluids.
Degree: PhD, Mathematics, 2016, Texas A&M University
URL: http://hdl.handle.net/1969.1/157947
► Chaos and turbulence are two important topics in nonlinear dynamics. In this study, two problems related to chaos and turbulence modelling are presented. They are…
(more)
▼ Chaos and turbulence are two important topics in nonlinear dynamics. In this study, two problems related to chaos and turbulence modelling are presented. They are the chaotic vibration phenomenon in high-dimensional partial differential equations and the emergence of the Navier-Stokes-alpha model for channel flows.
The study of the chaotic vibration phenomenon in high-dimensional partial differential equations is explained from both the numerical and theoretical aspects. In the numerical perspective, we have studied the chaotic vibration phenomenon of the 2D wave equation through numerical simulations. Based on the finite-volume method, we have built our own solver “img2Foam" in the Computational Fluid Dynamics software OpenFOAM (Open source Field Operation and Manipulation). We have implemented several numerical simulations containing both chaotic and non-chaotic cases. As for the theoretical perspective, we give a rigorous proof for the chaotic vibration phenomenon of the 2D non-strictly hyperbolic equation. After introducing two linear operators, the initial system of the 2D non-strictly hyperbolic equation is converted into a system of two coupled first order equations. By using the method of characteristics, we have found the explicit solution formulas of the new system. We have also found a regime of the parameters when the chaotic vibration phenomenon occurs by applying the period-doubling bifurcation theorem. Numerical simulations are presented to validate the theoretical results.
Inspired by the concept of the regular part of the weak attractor of the 3D Navier- Stokes equations, we concentrate on a restricted class of fluid flows to explore the transition from the Navier-Stokes equations to the Navier-Stokes-alpha model for channel flows. The Navier-Stokes equations have been widely used to describe the motion of viscous incompressible fluid flows. As an averaged version of the Navier- Stokes equations, the Navier-Stokes-alpha model has solid mathematical properties as well as reliable experimental matches. Therefore, the Navier-Stokes-alpha model is taken as an approximation for the dynamics of appropriately averaged turbulent fluid flows. We are interested in finding a connection between Navier-Stokes equations and the Navier-Stokes-alpha model in terms of the physical properties of the fluid flow. Given the hypothesis that the turbulence described by the Navier-Stokes-alpha model was partly due to the roughness of the walls, the transition from the Navier-Stokes equations into the Navier-Stokes-alpha model is presented by introducing a Reynolds type averaging.
Advisors/Committee Members: Chen, Goong (advisor), Chin, Siu A (committee member), Daripa, Prabir (committee member), Howard, Peter (committee member).
Subjects/Keywords: chaos; turbulence
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APA (6th Edition):
Tian, J. (2016). Study of Nonlinear Analysis and Chaos in Vibrations and Fluids. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/157947
Chicago Manual of Style (16th Edition):
Tian, Jing. “Study of Nonlinear Analysis and Chaos in Vibrations and Fluids.” 2016. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/157947.
MLA Handbook (7th Edition):
Tian, Jing. “Study of Nonlinear Analysis and Chaos in Vibrations and Fluids.” 2016. Web. 04 Mar 2021.
Vancouver:
Tian J. Study of Nonlinear Analysis and Chaos in Vibrations and Fluids. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/157947.
Council of Science Editors:
Tian J. Study of Nonlinear Analysis and Chaos in Vibrations and Fluids. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/157947
Texas A&M University
3.
Sheu, Hong-Li.
Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal.
Degree: PhD, Chemistry, 2014, Texas A&M University
URL: http://hdl.handle.net/1969.1/153848
► Infrared and Raman spectra of 2,6-difluoropyridine (26DFPy) and 2,3,5,6-tetrafluoropyridine were recorded and vibrational assignments made for their electronic ground states. Theoretical ab initio and density…
(more)
▼ Infrared and Raman spectra of 2,6-difluoropyridine (26DFPy) and 2,3,5,6-tetrafluoropyridine were recorded and vibrational assignments made for their electronic ground states. Theoretical ab initio and density functional theory (DFT) calculations were used to complement the experimental work. The electronic excited states of these molecules were investigated with ultraviolet absorption spectroscopy and theoretical CASSCF calculations. For 2,6-difluoropyridine the structure is planar in its S1(π,π*) electronic excited state, but a barrier to planarity of 256 cm^-1 was predicted for its S2(n,π*) electronic excited state which has its band origin at 37820.2 cm^-1. For 2,3,5,6-tetrafluoropyridine a barrier of 124 cm^-1 was predicted for the S1(π,π*) state which has its band origin at 35704.6 cm^-1. Lower frequencies for the out-of-plane ring bending vibrations for the electronic excited states result from the weaker π bonding within the pyridine ring in these states.
The infrared and Raman spectra of 2-chloro-, 3-chloro-, 2-bromo-, and 3-bromopyridine have been measured and assigned for the electronic ground state. Density functional theory (DFT) calculations at the B3LYP level of theory with the 6-311++G(d,p) basis set for vibrational frequencies produced excellent agreement with the experimental values. MP2 calculation methods with cc-pVTZ basis set were utilized to compute the molecular structures. A shortening of the N-C(2) bond resulting from halogen substitution on the C(2) carbon atom was shown for all 2-halopyridines.
Theoretical calculations including ab initio and density functional theory (DFT) methods were carried out to study the bond lengths and vibrational frequencies of halobismuthates and haloantimonates. The results were also compared to experimental crystal structures, and to the infrared and Raman spectra of these species. Although the presence of cations was neglected in the calculations, the observed trends in the bond distances and bond stretching vibrational frequencies were verified. External bonds across from bridging bonds are the shortest and have the highest stretching frequencies for all of the ions investigated. This supports the previously postulated trans effect.
The infrared and Raman spectra of the spiro molecule 2-cyclopenten-1-one ethylene ketal (CEK) have been recorded and compared to calculated spectra with good agreement. The structures and conformational energies for the two pairs of conformational minima, which can be defined in terms of ring-bending (x) and ring-twisting (τ) vibrational coordinates, have also been calculated. Utilizing the results from ab initio MP2/cc-PVTZ calculations, a two-dimensional potential energy surface (PES) was generated. The energy levels and wavefunctions for the PES were calculated and the characteristics of these were analyzed.
Advisors/Committee Members: Laane, Jaan (advisor), Hilty, Christian (committee member), Wheeler, Steven E. (committee member), Chen, Goong (committee member).
Subjects/Keywords: infrared (IR); Raman; ultraviolet absorption (UV); 2,6-difluoropyridine; 2,3,5,6-tetrafluoropyridine; ab initio; density functional theory (DFT); halobismuthate; CEK
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APA ·
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APA (6th Edition):
Sheu, H. (2014). Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153848
Chicago Manual of Style (16th Edition):
Sheu, Hong-Li. “Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal.” 2014. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/153848.
MLA Handbook (7th Edition):
Sheu, Hong-Li. “Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal.” 2014. Web. 04 Mar 2021.
Vancouver:
Sheu H. Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/153848.
Council of Science Editors:
Sheu H. Spectroscopic and Theoretical Investigations of Halopyridines, Halobismuthates and a Spiro Ketal. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153848
Texas A&M University
4.
Wang, Yi-Ching.
Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS.
Degree: PhD, Mathematics, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/155665
► Wind energy is the mainstream source of clean and renewable energy and it is also the fastest-growing source of sustainable energy in the world. In…
(more)
▼ Wind energy is the mainstream source of clean and renewable energy and it is also the fastest-growing source of sustainable energy in the world. In the Global Wind Energy Council's report in 2014, wind industry grew 44% worldwide. In order to optimize the efficiency of wind farms, it is important to observe wake interactions among wind turbines. Computational mathematics and mechanics provide fundamental methods and tools for simulating physical processes. Numerical computation can offer important insights and data that are either difficult or expensive to measure or to perform tests experimentally. In this dissertation, we use Computational Fluid Dynamics (CFD) software OpenFOAM and ANSYS FLUENT to simulate the wake effect of Horizontal Axis Wind Turbines (HAWT) and related problems. Numerical simulation can also help us comprehend and control man-made disasters. Air craft crashworthiness and human survivability are of utmost concerns in any emergency landing situation. Motivated by the air incidents lately, the disappearance of Malaysia Airlines Flight MH370 in March 2014 and Germanwings Flight 9525 crash in March 2015, we use Computational Structural Dynamics (CSD) software ANSYS Explicit Dynamics and LS-DYNA to try different numerical simulations of Airbus A320 crashing into a wall and compare the results to the reality.
We calculate three CFD problems in this dissertation: lid-driven problems, one turbine wake problem, and two serial turbines wake problem. We simulate a lid-driven flow in both two- (2D) and three-dimension (3D) to compare the simulation capability of the three turbulence modelings, i.e., Direct Numerical Simulation (DNS), Large Eddy Simulation (LES), and Reynolds-Averaged Navier-Stokes Equations Simulation (RANS) by OpenFOAM. Among these three turbulence models, we can find that LES is capable of capturing more details of turbulence flow. We simulate the airflow effect of one wind turbine with both fixed angular velocity and wind-driven case, run benchmark tests based on NRELs reports, and compare the numerical results under the same condition by OpenFOAM and FLUENT. For the fixed angular velocity case, we use wind speed 8
m/s and angular velocity of the wind turbine 75 deg/s. For the wind-driven case, we use wind speed 8
m/s and 16
m/s and the angular velocity of the wind turbine calculated by FLUENT converges faster than OpenFOAM case. We simulate the interactions of wake flow for two serial wind turbines by FLUENT. We use wind speed 8
m/s and angular velocity of the wind turbine 75 deg/s. The wake of former turbine affects the rear one and the diffusion of flow caused by two turbines can be seen clearly. For both one and two serial turbines problems, the turbulence model RANS kε is used. We calculate and simulate Airbus A320 crashing into a wall by ANSYS Explicit Dynamics and LS-DYNA. For ANSYS Explicit Dynamics, we use the angle of approach 0º, 15º, and 30º. For LS-DYNA, we only test the pitch angles 0º. For all cases, we use the speed of aircarft 200
m/s. The deformation of both aircraft…
Advisors/Committee Members: Chen, Goong (advisor), Yan, Catherine (committee member), Howard, Peter (committee member), Chin, Siu (committee member).
Subjects/Keywords: Computational Fluid Dynamics; Wind turbines; airplane crash
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APA (6th Edition):
Wang, Y. (2015). Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155665
Chicago Manual of Style (16th Edition):
Wang, Yi-Ching. “Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS.” 2015. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/155665.
MLA Handbook (7th Edition):
Wang, Yi-Ching. “Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS.” 2015. Web. 04 Mar 2021.
Vancouver:
Wang Y. Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/155665.
Council of Science Editors:
Wang Y. Numerical Computation of Wind Turbine Flows and Fluid Problem by OpenFOAM and ANSYS. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155665
Texas A&M University
5.
Yeh, Jean.
Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software.
Degree: PhD, Mathematics, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/174430
► In this dissertation, two problems are studied by computational mechanics. The first problem is the development and application of open-source software OpenFOAM to solve a…
(more)
▼ In this dissertation, two problems are studied by computational mechanics. The first problem is the development and application of open-source software OpenFOAM to solve a coupled system from shape optimization on a time-dependent changing domain to minimize a cost functional. Previously, researchers have treated this problem in 2D space, but here the author will extend the computation to 3D space. She will use the finite volume methods and OpenFOAM to build time-varying domains for optimization.
The second problem is about computational forensics. The author will discuss some photographic evidence, introduce mathematical modeling and do computational modeling regarding this particular Daallo Airlines bombing case, in which only a small amount of explosives was used. Mathematical and computer modeling of viscoplasticity, fracture and explosion by LS-DYNA will be used to study this problem and we computed on the supercomputer at
Texas A&
M University’s High Performance Research Computing Center. All of the numerical results of airplane bombing can be seen in the many video animations we made from the post-processed supercomputer results. The associated physical phenomena will also be interpreted.
Advisors/Committee Members: Chen, Goong (advisor), Daripa, Prabir (committee member), Fulling, Stephen (committee member), Chin, Siu Ah (committee member).
Subjects/Keywords: Shape Optimization; Airplane Bombing; OpenFOAM; LS-DYNA; Computational Simulation
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APA (6th Edition):
Yeh, J. (2018). Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174430
Chicago Manual of Style (16th Edition):
Yeh, Jean. “Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software.” 2018. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/174430.
MLA Handbook (7th Edition):
Yeh, Jean. “Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software.” 2018. Web. 04 Mar 2021.
Vancouver:
Yeh J. Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/174430.
Council of Science Editors:
Yeh J. Computational Mechanics for Shape Optimization and Airplane Bombing Based on OpenFOAM and LS-DYNA Software. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/174430
Texas A&M University
6.
Gu, Cong.
Computational Mechanics for Aircraft Water Entry and Wind Energy.
Degree: PhD, Mathematics, 2015, Texas A&M University
URL: http://hdl.handle.net/1969.1/156451
► In this thesis, two problems in computational mechanics, namely aircraft water entry and wind energy, have been studied together with description of related theory and…
(more)
▼ In this thesis, two problems in computational mechanics, namely aircraft water
entry and wind energy, have been studied together with description of related theory
and methodology. Fluid calculations are carried out with proper schemes and computational
techniques, including the use of dynamic mesh with OpenFOAM as the
platform. Subsequent analysis of the data provides valuable information for these
real world problems.
First, algorithms and numerical methods to solve the equations related to the
problems are proposed. Model problems are solved to test these methods. Then, in
the aircraft water entry problem, the complex and dynamic process of aircraft water
entry problem is simulated under several cases. External loading data has been
analyzed to estimate the severity of structural damage. The main finding is that the
vertical diving case is actually a reasonable theory regarding the final moments of
flight MH370 given the currently available information. In the wind energy problem,
blade resolved simulations of wind turbines are carried out. The proper orthogonal
decomposition analysis is shown to be capable of extracting dominant features of
the turbulent flow. Interaction between wind generators are studied to find out that
contra-rotating turbines can better capture energy in the wind.
It has been demonstrated that the computational approach is advantageous in
saving long and expensive processes of laboratory setup and measurements, while
providing valuable information to the subject problem.
Advisors/Committee Members: Chen, Goong (advisor), DeVore, Ronald (committee member), Stiller, Peter F (committee member), Chin, Siu Ah (committee member).
Subjects/Keywords: water entry; wind energy; computational fluid dynamics
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APA (6th Edition):
Gu, C. (2015). Computational Mechanics for Aircraft Water Entry and Wind Energy. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/156451
Chicago Manual of Style (16th Edition):
Gu, Cong. “Computational Mechanics for Aircraft Water Entry and Wind Energy.” 2015. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/156451.
MLA Handbook (7th Edition):
Gu, Cong. “Computational Mechanics for Aircraft Water Entry and Wind Energy.” 2015. Web. 04 Mar 2021.
Vancouver:
Gu C. Computational Mechanics for Aircraft Water Entry and Wind Energy. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/156451.
Council of Science Editors:
Gu C. Computational Mechanics for Aircraft Water Entry and Wind Energy. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/156451
Texas A&M University
7.
Yang, Shuai.
Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization.
Degree: PhD, Physics, 2013, Texas A&M University
URL: http://hdl.handle.net/1969.1/151685
► Quantum interference and coherence lead to many interesting phenomenon and applications in quantum optics. In this dissertation, we study the quantum coherent properties in the…
(more)
▼ Quantum interference and coherence lead to many interesting phenomenon and applications in quantum optics. In this dissertation, we study the quantum coherent properties in the following systems and aspects. We first investigate the optical bistability in a combined cavity-cold atoms system. In such a system the atom-photon interaction provides an optical lattice to the atoms and affects the mechanical motion of the atoms while atoms induce a position dependent phase shift on the cavity field. This highly nonlinearity induces optical bistability of intra-cavity photon number with respect to the pumping light added along the cavity axis. We show that the presence of this bistability can be controlled by a second pumping field added perpendicular to the cavity axis. It is also found that the critical input intensity of switching from one branch of bistability to the other depends on the the way of the field being added. This behavior is similar to the anomalous switching of the dispersive optical bistability of atomic media in the cavity. We also study the effect of counter-rotating terms in the control of spontaneous emission. We make use of a unitary transformation method and investigate the effect of dynamic energy shifts on the spontaneous emission modification via quantum interference in a four-level atomic system. We show that the counter-rotating terms, which are normally neglected in the usual investigation of atomic systems, do produce a significant influence on the evolution of the atomic amplitudes and the emission spectrum. This effect of counter-rotating terms can be observed in the time scale of the decay rate even when the dipole moments of the two upper levels are orthogonal to each other. The effect of counter-rotating terms on the spontaneous emission in a 3-D anisotropic photonic crystal is also discussed. It is shown that the behavior of the emission is similar to the case making rotating wave approximation, i.e., the localized and propagating fields are also separated by two characteristic atomic transition frequencies. However, the two characteristic frequencies are shifted due to the full Lamb shift which is obtained with counter-rotating terms being included in the Hamiltonian. We also utilize the unitary transformation method to show how the Lamb shift in a multi-level atom can be controlled by a driving field. Finally, we propose a subwavelength atom localization scheme for an atom located in a standing-wave field. The strategy is based on the observation that the photon statistics of resonance fluorescence depends on the position-dependent Rabi frequency.
Advisors/Committee Members: Zubairy, M. Suhail (advisor), Chen, Goong (committee member), Scully, Marlan O (committee member), Sokolov, Alexei (committee member).
Subjects/Keywords: Quantum coherence; optical bistability; cavity-BEC; spontaneous emission
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APA (6th Edition):
Yang, S. (2013). Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151685
Chicago Manual of Style (16th Edition):
Yang, Shuai. “Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization.” 2013. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/151685.
MLA Handbook (7th Edition):
Yang, Shuai. “Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization.” 2013. Web. 04 Mar 2021.
Vancouver:
Yang S. Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/151685.
Council of Science Editors:
Yang S. Quantum Optical Coherence: Applications in Photon Switching, Control of Spontaneous Emission and Atom Localization. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151685
Texas A&M University
8.
Yuan, Luqi.
Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER.
Degree: PhD, Physics, 2014, Texas A&M University
URL: http://hdl.handle.net/1969.1/153897
► This work is focused on quantum coherence and superradiant emission in a dense pencil-like multi-level medium where many novel effects appear such as transient lasing…
(more)
▼ This work is focused on quantum coherence and superradiant emission in a dense pencil-like multi-level medium where many novel effects appear such as transient lasing without inversion, coherence-brightened sky laser, and quantum amplification by superradiant emission of radiation.
We start from an interesting cascade model where quantum coherence effects can lead to surprising phenomena, gain without population inversion and gain suppression, under different parameters. We further show superradiant emission inside helium plasma. The population evolution shows the decay is significantly faster than collisional decoherence and spontaneous decay rates. This indicates superradiant coherent behavior of the atomic system inside the plasma.
Based on these results, we demonstrate lasing without inversion on a time scale shorter than the decoherence time. The possibility of transient lasing without inversion holds promise for lasing in the extreme-ultraviolet/x-ray regime. We propose experiments to demonstrate this in helium or helium-like ions plasma.
We also study coherent emission from ambient air and demonstrate efficient generation of laser-like beams directed both forward and backward with respect to a nanosecond ultraviolet pumping laser beam. The emission process exhibits nonadiabatic quantum coherence, which is similar in nature to Dicke superradiance. This coherence-brightened backward light source in air provides possibility for atmospheric remote sensing through a phase-matched coherent Raman scattering process.
Finally, we present a new kind of quantum amplifier, the QASER (quantum amplification by superradiant emission of radiation), based on collective superradiant emission which does not require initial population in the excited state. We show that parametric resonance between the driving field and collective superradiant oscillations of the atomic polarization can yield light amplification at high frequencies. The resulting superradiant amplifier is many orders of magnitude more efficient than nonlinear multiphoton excitation and holds promise as a new way to generate high-frequency coherent radiation.
Advisors/Committee Members: Scully, Marlan O (advisor), Sokolov, Alexei V (committee member), Zubairy, M. Suhail (committee member), Chen, Goong (committee member).
Subjects/Keywords: quantum coherence; superradiant emission
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APA (6th Edition):
Yuan, L. (2014). Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153897
Chicago Manual of Style (16th Edition):
Yuan, Luqi. “Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER.” 2014. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/153897.
MLA Handbook (7th Edition):
Yuan, Luqi. “Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER.” 2014. Web. 04 Mar 2021.
Vancouver:
Yuan L. Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/153897.
Council of Science Editors:
Yuan L. Quantum Coherence and Superradiant Emission: From Lasing Without Inversion to Sky Laser and the QASER. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153897
Texas A&M University
9.
Jha, Pankaj.
Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics.
Degree: PhD, Physics, 2012, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11688
► It is well known that the optical properties of multi-level atomic and molecular system can be controlled and manipulated efficiently using quantum coherence and interference,…
(more)
▼ It is well known that the optical properties of multi-level atomic and molecular system can be controlled and manipulated efficiently using quantum coherence and interference, which has led to many new effects in quantum optics for e.g. lasing action without population inversion, ultraslow light, high resolution nonlinear spectroscopy etc. Recent experimental and theoretical studies have also provided support for the hypothesis that biological systems uses quantum coherence. Nearly perfect excitation energy transfer in photosynthesis is an excellent example of this.
In this dissertation we studied quantum coherence and interference effects in the transient and the continuous-wave regimes. This study led to (i) the first experimental demonstration of carrier-envelope phase effects on bound-bound atomic excitation in multi-cycle regime (~15 cycles), (ii) a unique possibility for standoff detection of trace gases using their rotational and vibrational spectroscopic signals and from herein called Coherent Raman Umklappscattering, (iii) several possibilities for frequency up-conversion and generation of short-wavelength radiation using quantum coherence (iv) the measurement of spontaneous emission noise intensity in Yoked-superfluorescence scheme.
Applications of the obtained results are development of XUV (X-Ray) lasers, con- trolled superfluorescent (superradiant) emission, carrier-envelope phase effects, coherent Raman scattering in the backward direction, enhancement of efficiency for generating radiation in XUV and X-Ray regime using quantum coherence with and without population inversion and to extend XUV and X-Ray lasing to ~4.023 nm in Helium-like carbon.
Advisors/Committee Members: Scully, Marlan O. (advisor), Welch, George R. (committee member), Zubairy, Muhammad S. (committee member), Chen, Goong (committee member).
Subjects/Keywords: Lasing without inversion; X-Ray lasers; Yoked superfluorescence; Carrier-envelope phase effects; Laser induced atomic desorption; two-level system
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APA (6th Edition):
Jha, P. (2012). Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11688
Chicago Manual of Style (16th Edition):
Jha, Pankaj. “Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics.” 2012. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11688.
MLA Handbook (7th Edition):
Jha, Pankaj. “Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics.” 2012. Web. 04 Mar 2021.
Vancouver:
Jha P. Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11688.
Council of Science Editors:
Jha P. Novel Atomic Coherence and Interference Effects in Quantum Optics and Atomic Physics. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11688
Texas A&M University
10.
Wang, Changchun.
On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure.
Degree: PhD, Mathematics, 2012, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11171
► Variational structure plays an important role in critical point theory and methods. However many differential problems are non-variational i.e. they are not the Euler- Lagrange…
(more)
▼ Variational structure plays an important role in critical point theory and methods. However many differential problems are non-variational i.e. they are not the Euler- Lagrange equations of any variational functionals, which makes traditional critical point approach not applicable. In this thesis, two types of non-variational problems, a nonlinear eigen solution problem and a non-variational semi-linear elliptic system, are studied.
By considering nonlinear eigen problems on their variational energy profiles and using the implicit function theorem, an implicit minimax method is developed for numerically finding eigen solutions of focusing nonlinear Schrodinger equations subject to zero Dirichlet/Neumann boundary condition in the order of their eigenvalues. Its mathematical justification and some related properties, such as solution intensity preserving, bifurcation identification, etc., are established, which show some significant advantages of the new method over the usual ones in the literature. A new orthogonal subspace minimization method is also developed for finding multiple (eigen) solutions to defocusing nonlinear Schrodinger equations with certain
symmetries. Numerical results are presented to illustrate these methods.
A new joint local min orthogonal method is developed for finding multiple solutions of a non-variational semi-linear elliptic system. Mathematical justification and convergence of the method are discussed. A modified non-variational Gross-Pitaevskii system is used in numerical experiment to test the method.
Advisors/Committee Members: Zhou, Jianxin (advisor), Walton, Jay (committee member), Chen, Goong (committee member), Chin, Siu A. (committee member), Lazarov, Raytcho (committee member).
Subjects/Keywords: Nonlinear Schrodinger eigen problem; Nonvariational semilinear system; Implicit minimax method; Order in eigenvalues; Morse index; Bifurcation
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APA (6th Edition):
Wang, C. (2012). On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11171
Chicago Manual of Style (16th Edition):
Wang, Changchun. “On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure.” 2012. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11171.
MLA Handbook (7th Edition):
Wang, Changchun. “On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure.” 2012. Web. 04 Mar 2021.
Vancouver:
Wang C. On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11171.
Council of Science Editors:
Wang C. On Computing Multiple Solutions of Nonlinear PDEs Without Variational Structure. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11171
11.
Sen Gupta, Indranil.
Analysis of the Three-dimensional Superradiance Problem and Some Generalizations.
Degree: PhD, Mathematics, 2011, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8312
► We study the integral equation related to the three and higher dimensional superradiance problem. Collective radiation phenomena has attracted the attention of many physicists and…
(more)
▼ We study the integral equation related to the three and higher dimensional
superradiance problem. Collective radiation phenomena has attracted the attention
of many physicists and chemists since the pioneering work of R. H. Dicke in 1954.
We first consider the three-dimensional superradiance problem and find a differential
operator that commutes with the integral operator related to the problem. We
find all the eigenfunctions of the differential operator and obtain a complete set of
eigensolutions for the three-dimensional superradiance problem. Generalization of
the three-dimensional superradiance integral equation is provided. A commuting differential
operator is found for this generalized problem. For the three dimensional
superradiance problem, an alternative set of complete eigenfunctions is also provided.
The kernel for the superradiance problem when restricted to one-dimension is the
same as appeared in the works of Slepian, Landau and Pollak. The uniqueness of the
differential operator commuting with that kernel is indicated. Finally, a concentration
problem for the signals which are bandlimited in disjoint frequency-intervals is
considered. The problem is to determine which bandlimited signals lose the smallest
fraction of their energy when restricted in a given time interval. A numerical
algorithm for solution and convergence theorems are given. Orthogonality properties
of analytically extended eigenfunctions over L2(−∞,∞) are also proved. Numerical
computations are carried out in support of the theory.
Advisors/Committee Members: Chen, Goong (advisor), Boas, Harold (committee member), Herschbach, Dudley (committee member), Narcowich, Francis (committee member).
Subjects/Keywords: Quantum Mechanics; Special Functions; Differential Operator; Integral Operator; Eigenvalues and Eigenfunctions
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APA (6th Edition):
Sen Gupta, I. (2011). Analysis of the Three-dimensional Superradiance Problem and Some Generalizations. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8312
Chicago Manual of Style (16th Edition):
Sen Gupta, Indranil. “Analysis of the Three-dimensional Superradiance Problem and Some Generalizations.” 2011. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8312.
MLA Handbook (7th Edition):
Sen Gupta, Indranil. “Analysis of the Three-dimensional Superradiance Problem and Some Generalizations.” 2011. Web. 04 Mar 2021.
Vancouver:
Sen Gupta I. Analysis of the Three-dimensional Superradiance Problem and Some Generalizations. [Internet] [Doctoral dissertation]. Texas A&M University; 2011. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8312.
Council of Science Editors:
Sen Gupta I. Analysis of the Three-dimensional Superradiance Problem and Some Generalizations. [Doctoral Dissertation]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8312
12.
Hakami, Jabir Wali.
A Study on the Applications of Quantum Optical Coherence to Nano-Optics.
Degree: PhD, Physics, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/161281
► Optically controlled dipole-dipole interaction at submicrometers and subwavelength scales leads to many interesting phenomenon and remarkable potential applications in quantum optics, condensed matter physics, and…
(more)
▼ Optically controlled dipole-dipole interaction at submicrometers and subwavelength scales leads to many interesting phenomenon and remarkable potential applications in quantum optics, condensed matter physics, and today’s micro-devices. In this dissertation, we study the applications of quantum optical coherence to nano-optics in the following systems and aspects. On the one hand, chiral metamaterials has been previously reported as excellent candidates to realize both attractive and repulsive Casimir forces, where the existence of a repulsive Casimir force depends upon the strength of the chirality. On the other hand, nanoscale integration of metal nanoparticles and semiconductors is particularly interesting because the strengths of both materials are combined in such a hybrid system. In the first part of this work, we proposed a technical scheme to coherently control of the Casimir interaction energy with two identical chirality mediums. We took explicit caution regarding the requirements of passivity and causal response of the materials, since these requirements are essential for the application of the Lifshitz formula. The rare-earth metals’ atomic species, for instance, dysprosium, is proposed as an applicable medium for the forthcoming studies of possible experimental implementation of our technique. Secondly, we fully investigated the coherent control of the quantum optical properties of spontaneous emission spectra of a semiconductor quantum dot coupled to a metallic nanoparticle. The properties of the spontaneous emission spectra of such a system are studied in detail with and without involving the coherent field. The Rabi splitting effect in the spectrum emitted by the quantum dot under particular conditions is predicted for different sizes of the metal nanoparticles. We show that the spontaneous emission spectra of the transition coupled to surface plasmons may be further modified by adjusting the external coherent control on the adjacent transitions. In the third part, we propose a robust protocol to study the entanglement generation in a hybrid structure consisting of two quantum dots in the proximity of a metallic nanoshell. The entanglement arises impulsively due to common coupling to the plasmonic nanostructure, without demanding postselective measurement or mediating the dissipative environment. The long-lived entangled states can be created deterministically by optimizing the shell thickness as well as the ratio of the distances between the quantum dots and the surface of the shell. The loss of the system is greatly reduced even when the quantum dots are ultraclose to the shell, which signifies a slow decay rate of the coherence information and longtime entanglement preservation.
Advisors/Committee Members: Zubairy, M. Suhail (advisor), Scully, Marlan (committee member), Sokolov, Alexei (committee member), Chen, Goong (committee member).
Subjects/Keywords: Casimir forces; chiral metamaterials; metal nanoparticles; semiconductor quantum dots; coherent control; spontaneous emission spectra; entanglement.
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APA (6th Edition):
Hakami, J. W. (2017). A Study on the Applications of Quantum Optical Coherence to Nano-Optics. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/161281
Chicago Manual of Style (16th Edition):
Hakami, Jabir Wali. “A Study on the Applications of Quantum Optical Coherence to Nano-Optics.” 2017. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/161281.
MLA Handbook (7th Edition):
Hakami, Jabir Wali. “A Study on the Applications of Quantum Optical Coherence to Nano-Optics.” 2017. Web. 04 Mar 2021.
Vancouver:
Hakami JW. A Study on the Applications of Quantum Optical Coherence to Nano-Optics. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/161281.
Council of Science Editors:
Hakami JW. A Study on the Applications of Quantum Optical Coherence to Nano-Optics. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/161281
13.
Wang, Xiaohui.
Bayesian classification and survival analysis with curve predictors.
Degree: PhD, Statistics, 2009, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-1205
► We propose classification models for binary and multicategory data where the predictor is a random function. The functional predictor could be irregularly and sparsely sampled…
(more)
▼ We propose classification models for binary and multicategory data where the
predictor is a random function. The functional predictor could be irregularly and
sparsely sampled or characterized by high dimension and sharp localized changes. In
the former case, we employ Bayesian modeling utilizing flexible spline basis which is
widely used for functional regression. In the latter case, we use Bayesian modeling
with wavelet basis functions which have nice approximation properties over a large
class of functional spaces and can accommodate varieties of functional forms observed
in real life applications. We develop an unified hierarchical model which accommodates
both the adaptive spline or wavelet based function estimation model as well as
the logistic classification model. These two models are coupled together to borrow
strengths from each other in this unified hierarchical framework. The use of Gibbs
sampling with conjugate priors for posterior inference makes the method computationally
feasible. We compare the performance of the proposed models with the naive
models as well as existing alternatives by analyzing simulated as well as real data. We
also propose a Bayesian unified hierarchical model based on a proportional hazards model and generalized linear model for survival analysis with irregular longitudinal
covariates. This relatively simple joint model has two advantages. One is that using
spline basis simplifies the parameterizations while a flexible non-linear pattern of
the function is captured. The other is that joint modeling framework allows sharing
of the information between the regression of functional predictors and proportional
hazards modeling of survival data to improve the efficiency of estimation. The novel
method can be used not only for one functional predictor case, but also for multiple
functional predictors case. Our methods are applied to analyze real data sets and
compared with a parameterized regression method.
Advisors/Committee Members: Mallick, Bani K. (advisor), Chen, Goong (committee member), Longnecker, Michael (committee member), Wang, Suojin (committee member).
Subjects/Keywords: smoothing spline; wavelets; hierarchical modeling; generalized linear model; proportional hazards model
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APA (6th Edition):
Wang, X. (2009). Bayesian classification and survival analysis with curve predictors. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1205
Chicago Manual of Style (16th Edition):
Wang, Xiaohui. “Bayesian classification and survival analysis with curve predictors.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-1205.
MLA Handbook (7th Edition):
Wang, Xiaohui. “Bayesian classification and survival analysis with curve predictors.” 2009. Web. 04 Mar 2021.
Vancouver:
Wang X. Bayesian classification and survival analysis with curve predictors. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1205.
Council of Science Editors:
Wang X. Bayesian classification and survival analysis with curve predictors. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1205
14.
Zhang, Zhigang.
Modeling, analysis and control of quantum electronic devices.
Degree: PhD, Mathematics, 2009, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-1811
► This dissertation focuses on two connected areas: quantum computation and quantum control. Two proposals to construct a quantum computer, using nuclear magnetic resonance (NMR) and…
(more)
▼ This dissertation focuses on two connected areas: quantum computation and quantum
control. Two proposals to construct a quantum computer, using nuclear magnetic
resonance (NMR) and superconductivity, are introduced. We give details about the
modeling, qubit realization, one and two qubit gates and measurement in the language
that mathematicians can understand and fill gaps in the original literatures. Two
experimental examples using liquid NMR are also presented. Then we proceed to
investigate an example of quantum control, that of a magnetometer using quantum
feedback. Previous research has shown that feedback makes the measurement robust
to an unknown parameter, the number of atoms involved, with the assumption that
the feedback is noise free. To evaluate the effect of the feedback noise, we extend the
original model by an input noise term. We then compute the steady state performance
of the Kalman filter for both the closed-loop and open-loop cases and retrieve the
estimation error variances. The results are compared and criteria for evaluating the
effects of input noise are obtained. Computations and simulations show that the
level of input noise affects the measurement by changing the region where closed loop
feedback is beneficial.
Advisors/Committee Members: Chen, Goong (advisor), Hemmer, Philip (committee member), Pasciak, Joe (committee member), Rojas, Maurice J. (committee member).
Subjects/Keywords: quantum computation; quantum control; magnetometry; feedback; nuclear magnetic resonance
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APA ·
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MLA ·
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Export
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APA (6th Edition):
Zhang, Z. (2009). Modeling, analysis and control of quantum electronic devices. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1811
Chicago Manual of Style (16th Edition):
Zhang, Zhigang. “Modeling, analysis and control of quantum electronic devices.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-1811.
MLA Handbook (7th Edition):
Zhang, Zhigang. “Modeling, analysis and control of quantum electronic devices.” 2009. Web. 04 Mar 2021.
Vancouver:
Zhang Z. Modeling, analysis and control of quantum electronic devices. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1811.
Council of Science Editors:
Zhang Z. Modeling, analysis and control of quantum electronic devices. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1811
15.
Sete, Eyob Alebachew.
Quantum Coherence Effects in Novel Quantum Optical Systems.
Degree: PhD, Physics, 2012, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400
► Optical response of an active medium can substantially be modified when coherent superpositions of states are excited, that is, when systems display quantum coherence and…
(more)
▼ Optical response of an active medium can substantially be modified when coherent superpositions of states are excited, that is, when systems display quantum coherence and interference. This has led to fascinating applications in atomic and molecular systems. Examples include coherent population trapping, lasing without inversion, electromagnetically induced transparency, cooperative spontaneous emission, and quantum entanglement.
We study quantum coherence effects in several quantum optical systems and find interesting applications. We show that quantum coherence can lead to transient Raman lasing and lasing without inversion in short wavelength spectral regions – extreme ultraviolet and x-ray – without the requirement of incoherent pumping. For example, we demonstrate transient Raman lasing at 58.4 nm in Helium atom and transient lasing without inversion at 6.1 nm in Helium-like Boron (triply-ionized Boron). We also investigate dynamical properties of a collective superradiant state prepared by absorption of a single photon when the size of the sample is larger than the radiation wavelength. We show that for large number of atoms such a state, to a good approximation, decays exponentially with a rate proportional to the number of atoms. We also find that the collective frequency shift resulting from repeated emission and reabsorption of short-lived virtual photons is proportional to the number of species in the sample. Furthermore, we examine how a position-dependent excitation phase affects the evolution of entanglement between two dipole-coupled qubits. It turns out that the coherence induced by position-dependent excitation phase slows down the otherwise fast decay of the two-qubit entanglement. We also show that it is possible to entangle two spatially separated and uncoupled qubits via interaction with correlated photons in a cavity quantum electrodynamics setup. Finally, we analyze how quantum coherence can be used to generate continuous-variable entanglement in quantum-beat lasers in steady state and propose possible implementation in quantum lithography.
Advisors/Committee Members: Scully, Marlan O. (advisor), Zubairy, Muhammad S. (committee member), Kocharovskaya, Olga (committee member), Chen, Goong (committee member).
Subjects/Keywords: Quantum coherence effects; extreme ultraviolet and x-ray lasers; transient lasing without inversion; transient Raman lasing; superradiance; Collective Lamb (frequency) shift; dipole-coupled qubit entanglement; light-to-matter entanglement transfer; quantum beat laser; continuous-variable entanglement; quantum lithography
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Manager
APA (6th Edition):
Sete, E. A. (2012). Quantum Coherence Effects in Novel Quantum Optical Systems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400
Chicago Manual of Style (16th Edition):
Sete, Eyob Alebachew. “Quantum Coherence Effects in Novel Quantum Optical Systems.” 2012. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400.
MLA Handbook (7th Edition):
Sete, Eyob Alebachew. “Quantum Coherence Effects in Novel Quantum Optical Systems.” 2012. Web. 04 Mar 2021.
Vancouver:
Sete EA. Quantum Coherence Effects in Novel Quantum Optical Systems. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400.
Council of Science Editors:
Sete EA. Quantum Coherence Effects in Novel Quantum Optical Systems. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11400
16.
Liao, Zeyang.
Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient.
Degree: PhD, Physics, 2014, Texas A&M University
URL: http://hdl.handle.net/1969.1/153506
► The resolution of traditional optical microscope and optical lithography is limited by about half wavelength of the light source, which is well known as the…
(more)
▼ The resolution of traditional optical microscope and optical lithography is limited by about half wavelength of the light source, which is well known as the diffraction limit or Abbe limit. The resolution limit is due to the missing of high spatial frequency components in the far-field. One way to achieve high resolution is to move the detector into the near-field region where the evanescent wave can be collected. However, these methods are surface-bound and usually very slow which have limited applications. It has long been an interesting and important question about how to overcome the diffraction limit in the far-field.
For optical lithography, a number of methods have been proposed to overcome the diffraction limit such as multi-photon scanning, quantum entanglement, quantum inspired process (e.g., dopperlon), and quantum dark state. However, these methods either require multi-photon absorber, quantum entanglement, or multi-energy levels, which restrict them from extending to higher resolution in practice. In this thesis, we showed that sub-diffraction-limited resolution can be generated by the coherent Rabi gradient. This method does not require multi-photon absorber or quantum entanglement but just quantum coherence of the medium. Extension from lower resolution to higher resolution is very straightforward where we just need to increase the pulse intensity or pulse duration. We also proposed two atom lithography experiments based on the Rabi gradient. The first one uses Rubidium Rydberg atom and microwave where we showed that sub-micrometer line spacing is possible. The second one uses Chromium atom and optical field where we showed that sub-10nm line spacing is possible while the wavelength of the light is about 400nm.
For optical imaging, a number of methods have also been proposed to achieve super-resolution such as multi-photon microscope, stimulated-emission-depletion, structured illumination microscopy, centroid-based techniques and metamaterial-based lens. Here, we will show a new method to achieve resolution beyond the diffraction limit which we called it resonance fluorescence microscopy. Resonance fluorescence has been proposed to localize a single atom with resolution beyond the diffraction limit. The separation between two atoms can also be extracted from the resonance
fluorescence spectrum. To develop it as microscopy, we need to evaluate the resonance fluorescence spectrum of multiple-atom system. We analytically solved the general feature of the spectrum when the Rabi frequency is much larger than the dipole-dipole interaction and showed how to extract the spatial information of the atoms with resolution far beyond the diffraction limit. This method is entirely based on far-field techniques and it does not require point-by-point scanning.
Advisors/Committee Members: Zubairy, M. Suhail (advisor), Scully, Marlan O. (committee member), Sokolov, Alexei (committee member), Chen, Goong (committee member).
Subjects/Keywords: Optical lithography; Optical imaging; super-resolution; diffraction limit
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APA (6th Edition):
Liao, Z. (2014). Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/153506
Chicago Manual of Style (16th Edition):
Liao, Zeyang. “Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient.” 2014. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/153506.
MLA Handbook (7th Edition):
Liao, Zeyang. “Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient.” 2014. Web. 04 Mar 2021.
Vancouver:
Liao Z. Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/153506.
Council of Science Editors:
Liao Z. Optical Lithography and Atom Localization beyond the Diffraction Limit via Rabi Gradient. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/153506
17.
Hsu, Paul Steve.
Magneto-optical control of coherent nonlinear processes.
Degree: PhD, Physics, 2009, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2813
► Laser-atom interactions create atomic coherence and large nonlinear atomic polarization. We investigate resonant laser-atom interactions to generate large nonlinearities and control them using magneto-optical fields.…
(more)
▼ Laser-atom interactions create atomic coherence and large nonlinear atomic polarization.
We investigate resonant laser-atom interactions to generate large nonlinearities
and control them using magneto-optical fields. Coherent control of high-order
susceptibilities and magneto-optical rotation are demonstrated. Experiments are supported
by theoretical studies that effectively describe the observed phenomena.
It is shown that a new coherent field, with polarization orthogonal to a weak
signal field, can be parametrically generated via an all-resonant four-wave-mixing
process. This is demonstrated in a double-ladder system having two intermediate
states between a ground and an excited state. It is shown that the parametricgeneration
process can be coherently controlled by coupling lasers and magnetic fields.
It is theoretically established that the underlying physics is a resonant three-photon
process with a wide domain of control parameters.
Electromagnetically induced transparency (EIT), where absorption of a weak
probe is suppressed via quantum interference, is demonstrated in a usual three-level
ladder system. It is observed that in contrast with EIT in a usual ladder system,
addition of a second channel helps to suppress the absorption of two weak probe
fields in the double-ladder system. The resulting enhancement of transmission in two
different channels is due to gain caused by three-photon processes.
Coherent control is strongly limited by coherence lifetime, which is the inverse of
the dephasing rate. A lambda-system, having two ground states coupled to a common
excited state by lasers, can generate a new eigen (dark)-state that is transparent to incoming fields and hence suppresses fluorescence. However, ground-state dephasing
perturbs the dark state. A new method for measuring the ground-state dephasing
rate from fluorescence signals is proposed and a proof-of-principle experiment demonstrated.
While two laser fields in a lambda-system are resonant with their respective
transitions, the atomic polarizations are very sensitive to an applied magnetic field.
This effect can be used for optical magnetometry. The degree of sensitivity of the
magnetometer is determined by two competing parameters–atomic density and laser
intensity. It is shown experimentally that the optimal sensitivity reaches saturation,
which is contrary to the idea that sensitivity increases indefinitely with an increase
in the above parameters.
Advisors/Committee Members: Welch,George R. (advisor), Belyanin, Alexey (committee member), Chen, Goong (committee member), Sokolov, Alexei V. (committee member).
Subjects/Keywords: atomic coherence; electromagnetically induced transparency; magneto-optical raotation; doule-ladder system; nonlinear processes
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APA (6th Edition):
Hsu, P. S. (2009). Magneto-optical control of coherent nonlinear processes. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2813
Chicago Manual of Style (16th Edition):
Hsu, Paul Steve. “Magneto-optical control of coherent nonlinear processes.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2813.
MLA Handbook (7th Edition):
Hsu, Paul Steve. “Magneto-optical control of coherent nonlinear processes.” 2009. Web. 04 Mar 2021.
Vancouver:
Hsu PS. Magneto-optical control of coherent nonlinear processes. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2813.
Council of Science Editors:
Hsu PS. Magneto-optical control of coherent nonlinear processes. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2813
18.
Sun, Dong.
Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures.
Degree: PhD, Physics, 2012, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10508
► Quantum coherence and interference(QCI) effects have been studied for decades and are widely exploited in many areas. For media with QCI effect, the optical properties…
(more)
▼ Quantum coherence and interference(QCI) effects have been studied for decades and are widely exploited in many areas. For media with QCI effect, the optical properties can change drastically, which leads to many interesting effects, such as coherent population trapping, electromagnetically induced transparency(EIT), lasing without population inversion(LWI) and so on.
We have theoretically studied the pulsed regime of EIT. In particular, simulations of propagation of gaussian and 0 - pi co-propagating laser pulses in a medium consisting of 3-level Lambda-atoms have been performed. It has been found that, even at the two-photon resonance, the length of propagation for the 0 - pi pulses is much smaller than that for the Gaussian probe pulses. We explained such a behavior using the dark and bright basis and the dressed state basis. Some possible applications are discussed.
We also investigated the collision-induced coherence of two decay channels along two optical transitions. Quantum interference will suppress the spontaneous emission. The degree of this suppression is measured by the branch ratio of these two transitions. Our preliminary calculations show that a significant decrease of the branching ratio with increase of electron densities is reproduced in the theory.
We have developed a new variant of Raman spectroscopy with shaped femtosecond pulses. It has several advantages to be applied in multiscatterd media. It is based on change of the spectra of femtopulses due to Raman scattering (stimulated or coherent). The technique can be used for a broad range of applications from atomic and molecular optical and IR spectroscopy to spore detection and tissue microscopy.
Finally, we have shown that Fano interference in the decay channels of three levels system can lead to considerably different absorption and emission profiles. We found that a coherence can be built up in the ground state doublet whose strength depends on a coupling parameter that arises from Fano interference. This can in principle lead to breaking of the detail balance between the absorption and emission processes in atomic systems.
Advisors/Committee Members: Scully, Marlan O. (advisor), Rostovtsev, Yuri V. (advisor), Chen, Goong (committee member), Welch, George R. (committee member), Zubairy, Suhail M. (committee member).
Subjects/Keywords: Quantum Coherence; Electromagnetically Induced Transparency; Raman Scattering; Branching Ratio; Fano Interference
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APA (6th Edition):
Sun, D. (2012). Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10508
Chicago Manual of Style (16th Edition):
Sun, Dong. “Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures.” 2012. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10508.
MLA Handbook (7th Edition):
Sun, Dong. “Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures.” 2012. Web. 04 Mar 2021.
Vancouver:
Sun D. Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10508.
Council of Science Editors:
Sun D. Extending Coherent Effects from Atomic and Molecular Media to Plasmas and Nanostructures. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10508
Texas A&M University
19.
Urthaler Lapeira, Yetzirah Yksya.
On simple and accurate finite element models for nonlinear bending analysis of beams and plates.
Degree: PhD, Mechanical Engineering, 2007, Texas A&M University
URL: http://hdl.handle.net/1969.1/5779
► This study is concerned with the development of simple and accurate alternative finite element models to displacement finite element models for geometrically nonlinear bending analysis…
(more)
▼ This study is concerned with the development of simple and accurate alternative finite element models to displacement finite element models for geometrically
nonlinear bending analysis of beams and plates. First, a unified corotational beam
finite element that incorporates the kinematics of classical as well as refined beam
theories, including the Timoshenko and Reddy beam theories, is developed in a single
finite element. The governing equations are written in a "corotational" local frame
that rotates with the element and with respect to which the standard linear engineering relations between strains and internal forces are valid. The element is based
on Lagrange interpolation of the axial displacement, Hermite cubic interpolation of
the transverse displacement, and related quadratic interpolation of the rotation, and
it does not experience shear locking. The model is verified by comparisons with exact and/or approximate solutions available in the literature. Very good agreement is
found in all cases.
Next, a finite element model is developed using a mixed formulation of the first-order shear deformation theory of laminated composite plates. A p-type Lagrangian
basis is used to approximate the nodal degrees of freedom that consist of three displacements, two rotations, and three moment resultants. The geometric nonlinearity,
in the sense of the von Kõarman, is included in the plate theory. The mixed plate
element developed herein is employed in the linear and nonlinear bending analysis of a variety of layered composite rectangular plates. The effects of transverse
shear deformation, material anisotropy, and bending-stretching coupling on deflections and stresses are investigated. The predictive capability of the present model
is demonstrated by comparison with analytical, experimental, and numerical solutions available in the literature. The model provides an accurate prediction of the
global bending response of thin and moderately thick plates subjected to moderate
and moderately large rotations. The inclusion of the bending moments at the nodes
results in increased accuracy in the computation of stresses over those determined by
conventional displacement-based finite element models. The many results presented
here for geometrically nonlinear bending analysis of beams and plates should serve as
reference for future investigations.
Advisors/Committee Members: Reddy, JN (advisor), Chen, Goong (committee member), Hogan, Harry (committee member), Suh, Steve (committee member).
Subjects/Keywords: finite element analysis; structures
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Export
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APA (6th Edition):
Urthaler Lapeira, Y. Y. (2007). On simple and accurate finite element models for nonlinear bending analysis of beams and plates. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/5779
Chicago Manual of Style (16th Edition):
Urthaler Lapeira, Yetzirah Yksya. “On simple and accurate finite element models for nonlinear bending analysis of beams and plates.” 2007. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/5779.
MLA Handbook (7th Edition):
Urthaler Lapeira, Yetzirah Yksya. “On simple and accurate finite element models for nonlinear bending analysis of beams and plates.” 2007. Web. 04 Mar 2021.
Vancouver:
Urthaler Lapeira YY. On simple and accurate finite element models for nonlinear bending analysis of beams and plates. [Internet] [Doctoral dissertation]. Texas A&M University; 2007. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/5779.
Council of Science Editors:
Urthaler Lapeira YY. On simple and accurate finite element models for nonlinear bending analysis of beams and plates. [Doctoral Dissertation]. Texas A&M University; 2007. Available from: http://hdl.handle.net/1969.1/5779
Texas A&M University
20.
He, Linli.
Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations.
Degree: PhD, Computer Science, 2007, Texas A&M University
URL: http://hdl.handle.net/1969.1/5864
► The aggregate power of all resources on the Internet is enormous. The Internet can be viewed as a massive virtual organization that holds tremendous amounts…
(more)
▼ The aggregate power of all resources on the Internet is enormous. The Internet can
be viewed as a massive virtual organization that holds tremendous amounts of information
and resources with different ownerships. However, little is known about how to run this
organization efficiently.
This dissertation studies the problems of distributed task and resource allocation
among self-interested agents in virtual organizations. The developed solutions are not
allocation mechanisms that can be imposed by a centralized designer, but decentralized
interaction mechanisms that provide incentives to self-interested agents to behave
cooperatively. These mechanisms also take computational tractability into consideration
due to the inherent complexity of distributed task and resource allocation problems.
Targeted allocation mechanisms can achieve global task allocation efficiency in a
virtual organization and establish stable resource-sharing communities based on agentsâÃÂÃÂ
own decisions about whether or not to behave cooperatively. This high level goal requires
solving the following problems: synthetic task allocation, decentralized coalition formation
and automated multiparty negotiation. For synthetic task allocation, in which each task needs to be accomplished by a
virtual team composed of self-interested agents from different real organizations, my
approach is to formalize the synthetic task allocation problem as an algorithmic mechanism
design optimization problem. I have developed two approximation mechanisms that I prove
are incentive compatible for a synthetic task allocation problem.
This dissertation also develops a decentralized coalition formation mechanism,
which is based on explicit negotiation among self-interested agents. Each agent makes its
own decisions about whether or not to join a candidate coalition. The resulting coalitions
are stable in the core in terms of coalition rationality. I have applied this mechanism to
form resource sharing coalitions in computational grids and buyer coalitions in electronic
markets.
The developed negotiation mechanism in the decentralized coalition formation
mechanism realizes automated multilateral negotiation among self-interested agents who
have symmetric authority (i.e., no mediator exists and agents are peers).
In combination, the decentralized allocation mechanisms presented in this
dissertation lay a foundation for realizing automated resource management in open and
scalable virtual organizations.
Advisors/Committee Members: Ioerger, Thomas R. (advisor), Bettati, Riccardo (committee member), Chen, Goong (committee member), Chen, Jianer (committee member).
Subjects/Keywords: mechanism design; self-interested agents; virtual organization
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
He, L. (2007). Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/5864
Chicago Manual of Style (16th Edition):
He, Linli. “Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations.” 2007. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/5864.
MLA Handbook (7th Edition):
He, Linli. “Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations.” 2007. Web. 04 Mar 2021.
Vancouver:
He L. Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations. [Internet] [Doctoral dissertation]. Texas A&M University; 2007. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/5864.
Council of Science Editors:
He L. Mechanism design for distributed task and resource allocation among self-interested agents in virtual organizations. [Doctoral Dissertation]. Texas A&M University; 2007. Available from: http://hdl.handle.net/1969.1/5864
Texas A&M University
21.
Feng, Zhaosheng.
Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation.
Degree: PhD, Mathematics, 2004, Texas A&M University
URL: http://hdl.handle.net/1969.1/1078
► Many physical phenomena can be described by nonlinear models. The last few decades have seen an enormous growth of the applicability of nonlinear models and…
(more)
▼ Many physical phenomena can be described by nonlinear models. The last few decades have seen an enormous growth of the applicability of nonlinear models and of the development of related nonlinear concepts. This has been driven by modern computer power as well as by the discovery of new mathematical techniques, which include two contrasting themes: (i) the theory of dynamical systems, most popularly associated with the study of chaos, and (ii) the theory of integrable systems associated, among other things, with the study of solitons.
In this dissertation, we study two nonlinear models. One is the 1-dimensional vibrating string satisfying wtt − wxx = 0 with van der Pol boundary conditions. We formulate the problem into an equivalent first order hyperbolic system, and use the method of characteristics to derive a nonlinear reflection relation caused by the nonlinear boundary conditions. Thus, the problem is reduced to the discrete iteration problem of the type un+1 = F (un). Periodic solutions are investigated, an invariant interval for the Abel equation is studied, and numerical simulations and visualizations with different coefficients are illustrated.
The other model is the Korteweg-de Vries-Burgers (KdVB) equation. In this dissertation, we proposed two new approaches: One is what we currently call First Integral Method, which is based on the ring theory of commutative algebra. Applying the Hilbert-Nullstellensatz, we reduce the KdVB equation to a first-order integrable ordinary differential equation. The other approach is called the Coordinate Transformation Method, which involves a series of variable transformations. Some new results on the traveling wave solution are established by using these two methods, which not only are more general than the existing ones in the previous literature, but also indicate that some corresponding solutions presented in the literature contain errors. We clarify the errors and instead give a refined result.
Advisors/Committee Members: Chen, Goong (advisor), Foias, Ciprian (committee member), Friesen, Donald (committee member), Pasciak, Joe (committee member).
Subjects/Keywords: Nonlinear equation; traveling wave; soliton; first integral; proper solution; chaos; period doubling
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APA ·
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MLA ·
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CSE |
Export
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APA (6th Edition):
Feng, Z. (2004). Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/1078
Chicago Manual of Style (16th Edition):
Feng, Zhaosheng. “Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation.” 2004. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/1078.
MLA Handbook (7th Edition):
Feng, Zhaosheng. “Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation.” 2004. Web. 04 Mar 2021.
Vancouver:
Feng Z. Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation. [Internet] [Doctoral dissertation]. Texas A&M University; 2004. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/1078.
Council of Science Editors:
Feng Z. Some results on the 1D linear wave equation with van der Pol type nonlinear boundary conditionsand the Korteweg-de Vries-Burgers equation. [Doctoral Dissertation]. Texas A&M University; 2004. Available from: http://hdl.handle.net/1969.1/1078
Texas A&M University
22.
Kar, Rahul.
Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability.
Degree: MS, Mechanical Engineering, 2005, Texas A&M University
URL: http://hdl.handle.net/1969.1/2596
► Rotordynamic instability can be disastrous for the operation of high speed turbomachinery in the industry. Most ??instabilities?? are due to de-stabilizing cross coupled forces from…
(more)
▼ Rotordynamic instability can be disastrous for the operation of high speed turbomachinery in the industry. Most ??instabilities?? are due to de-stabilizing cross coupled forces from variable fluid dynamic pressure around a rotor component, acting in the direction of the forward whirl and causing subsynchronous orbiting of the rotor. However, all subsynchronous whirling is not unstable and methods to diagnose the potentially unstable kind are critical to the health of the rotor-bearing system. The objective of this thesis is to explore means of diagnosing whether subsynchronous vibrations are benign or have the potential to become unstable. Several methods will be detailed to draw lines of demarcation between the two. Considerable focus of the research has been on subharmonic vibrations induced from non-linear bearing stiffness and the study of vibration signals typical to such cases. An analytical model of a short-rigid rotor with stiffness non-linearity is used for numerical simulations and the results are verified with actual experiments. Orbits filtered at the subsynchronous frequency are shown as a diagnostic tool to indicate benign vibrations as well as ??frequency tracking?? and agreement of the frequency with known eigenvalues. Several test rigs are utilized to practically demonstrate the above conclusions. A remarkable finding has been the possibility of diagnosing instability using the synchronous phase angle. The synchronous phase angle ?? is the angle by which the unbalance vector leads the vibration vector. Experiments have proved that ?? changes appreciably when there is a de-stabilizing cross coupled force acting on the rotor as compared to when there is none. A special technique to calculate the change in ?? with cross-coupling is outlined along with empirical results to exemplify the case. Subsequently, a correlation between the synchronous phase angle and the phase angle measured with most industrial balancing instruments is derived so that the actual measurement of the true phase angle is not a necessity for diagnosis. Requirements of advanced signal analysis techniques have led to the development of an extremely powerful rotordynamic measurement teststand ?? ??LVTRC??. The software was developed in tandem with this thesis project. It is a stand-alone application that can be used for field measurements and analysis by turbomachinery companies.
Advisors/Committee Members: Vance, John M. (advisor), Chen, Goong (committee member), Palazzolo, A. (committee member).
Subjects/Keywords: Rotordynamic; Instability; LabVIEW; LVTRC; Diagnostics; Signal analysis; Unstable; Vibration; Rotor design; Subharmonic; Frequency demultiplication; non-linear stiffness; Synchronous Phase angle; Frequency tracking; Short rigid rotor
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APA ·
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Export
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APA (6th Edition):
Kar, R. (2005). Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/2596
Chicago Manual of Style (16th Edition):
Kar, Rahul. “Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability.” 2005. Masters Thesis, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/2596.
MLA Handbook (7th Edition):
Kar, Rahul. “Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability.” 2005. Web. 04 Mar 2021.
Vancouver:
Kar R. Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability. [Internet] [Masters thesis]. Texas A&M University; 2005. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/2596.
Council of Science Editors:
Kar R. Diagnostics of subsynchronous vibrations in rotating machinery - methodologies to identify potential instability. [Masters Thesis]. Texas A&M University; 2005. Available from: http://hdl.handle.net/1969.1/2596
Texas A&M University
23.
Yao, Xudong.
Minimax methods for finding multiple saddle critical points in Banach spaces and their applications.
Degree: PhD, Mathematics, 2005, Texas A&M University
URL: http://hdl.handle.net/1969.1/2732
► This dissertation was to study computational theory and methods for ?nding multiple saddle critical points in Banach spaces. Two local minimax methods were developed for…
(more)
▼ This dissertation was to study computational theory and methods for ?nding multiple saddle critical points in Banach spaces. Two local minimax methods were developed for this purpose. One was for unconstrained cases and the other was for constrained cases. First, two local minmax characterization of saddle critical points in Banach spaces were established. Based on these two local minmax characterizations, two local minimax algorithms were designed. Their ?ow charts were presented. Then convergence analysis of the algorithms were carried out. Under certain assumptions, a subsequence convergence and a point-to-set convergence were obtained. Furthermore, a relation between the convergence rates of the functional value sequence and corresponding gradient sequence was derived. Techniques to implement the algorithms were discussed. In numerical experiments, those techniques have been successfully implemented to solve for multiple solutions of several quasilinear elliptic boundary value problems and multiple eigenpairs of the well known nonlinear p-Laplacian operator. Numerical solutions were presented by their pro?les for visualization. Several interesting phenomena of the solutions of quasilinear elliptic boundary value problems and the eigenpairs of the p-Laplacian operator have been observed and are open for further investigation. As a generalization of the above results, nonsmooth critical points were considered for locally Lipschitz continuous functionals. A local minmax characterization of nonsmooth saddle critical points was also established. To establish its version in Banach spaces, a new notion, pseudo-generalized-gradient has to be introduced. Based on the characterization, a local minimax algorithm for ?nding multiple nonsmooth saddle critical points was proposed for further study.
Advisors/Committee Members: Zhou, Jianxin (advisor), Chen, Goong (committee member), Walton, Jay (committee member), Vadali, Srinivas Rao (committee member).
Subjects/Keywords: Multiple Saddle Critical Points; Multiple Eigenpairs; Multiple Nonsmooth Saddle Critical Points; Minmax Characterization; Minimax Algorithm; Quasilinear Elliptic PDE; p-Laplacian Operator; Banach Space
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APA ·
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MLA ·
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Export
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Manager
APA (6th Edition):
Yao, X. (2005). Minimax methods for finding multiple saddle critical points in Banach spaces and their applications. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/2732
Chicago Manual of Style (16th Edition):
Yao, Xudong. “Minimax methods for finding multiple saddle critical points in Banach spaces and their applications.” 2005. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/2732.
MLA Handbook (7th Edition):
Yao, Xudong. “Minimax methods for finding multiple saddle critical points in Banach spaces and their applications.” 2005. Web. 04 Mar 2021.
Vancouver:
Yao X. Minimax methods for finding multiple saddle critical points in Banach spaces and their applications. [Internet] [Doctoral dissertation]. Texas A&M University; 2005. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/2732.
Council of Science Editors:
Yao X. Minimax methods for finding multiple saddle critical points in Banach spaces and their applications. [Doctoral Dissertation]. Texas A&M University; 2005. Available from: http://hdl.handle.net/1969.1/2732
Texas A&M University
24.
Luo, Hao.
Tsallis Entropy Based Velocity Distribution in Open Channel Flows.
Degree: MS, Biological and Agricultural Engineering, 2010, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462
► The Tsallis entropy is applied to derive both 1-D and 2-D velocity distributions in an open channel cross section. These distributions contain a parameter m…
(more)
▼ The Tsallis entropy is applied to derive both 1-D and 2-D velocity distributions in an open channel cross section. These distributions contain a parameter
m through which the Tsallis entropy becomes a generalization of the Shannon entropy. Different
m parameter
values are examined to determine the best value for describing the velocity distribution.Two Lagrangian parameters that are involved in the final form of 1-D velocity distribution equation are determined from observations of mean velocity and the maximum velocity at the water surface. For channels which are not wide and where the maximum velocity does not occur at the water surface, a 2-D velocity distribution is
more appropriate. The Tsallis entropy is applied to derive 2-D velocity distributions. A
new parameter
M is introduced which represents the hydraulic characteristics of the channel. The derived velocity distributions are verified using both field data and experimental data. The advantages are found by comparing with Parandtl-von Karman,
power law and Chiu’s velocity distributions.
Advisors/Committee Members: Singh, Vijay (advisor), Wurbs, Ralph (committee member), Chen, Goong (committee member).
Subjects/Keywords: Tsallis entropy; velocity distribution; hydraulics; uncertainty
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Manager
APA (6th Edition):
Luo, H. (2010). Tsallis Entropy Based Velocity Distribution in Open Channel Flows. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462
Chicago Manual of Style (16th Edition):
Luo, Hao. “Tsallis Entropy Based Velocity Distribution in Open Channel Flows.” 2010. Masters Thesis, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462.
MLA Handbook (7th Edition):
Luo, Hao. “Tsallis Entropy Based Velocity Distribution in Open Channel Flows.” 2010. Web. 04 Mar 2021.
Vancouver:
Luo H. Tsallis Entropy Based Velocity Distribution in Open Channel Flows. [Internet] [Masters thesis]. Texas A&M University; 2010. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462.
Council of Science Editors:
Luo H. Tsallis Entropy Based Velocity Distribution in Open Channel Flows. [Masters Thesis]. Texas A&M University; 2010. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462
Texas A&M University
25.
Roque Sol, Marco A.
A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps.
Degree: PhD, Mathematics, 2009, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-1810
► We study some topological properties of dynamical systems. In particular the rela- tionship between spatio-temporal chaotic and Li-Yorke sensitive dynamical systems establishing that for minimal…
(more)
▼ We study some topological properties of dynamical systems. In particular the rela-
tionship between spatio-temporal chaotic and Li-Yorke sensitive dynamical systems
establishing that for minimal dynamical systems those properties are equivalent. In
the same direction we show that being a Li-Yorke sensitive dynamical system implies
that the system is also Li-Yorke chaotic. On the other hand we survey the possibility
of lifting some topological properties from a given dynamical system (Y, S) to an-
other (X, T). After studying some basic facts about topological dynamical systems,
we move to the particular case of interval maps. We know that through the knowl-
edge of interval maps, f : I → I, precious information about the chaotic behavior
of general nonlinear dynamical systems can be obtained. It is also well known that
the analysis of the spectrum of time series encloses important material related to the
signal itself. In this work we look for possible connections between chaotic dynamical
systems and the behavior of its Fourier coefficients. We have found that a natural
bridge between these two concepts is given by the total variation of a function and
its connection with the topological entropy associated to the n-th iteration, fn(x), of
the map. Working in a natural way using the Sobolev spaces Wp,q(I) we show how
the Fourier coefficients are related to the chaoticity of interval maps.
Advisors/Committee Members: Chen, Goong (advisor), Stiller, Peter (committee member), Zhou, Jianxin (committee member), Zubairy, Suhail (committee member).
Subjects/Keywords: Li-Yorke Sensitive; Li-Yorke Chaotic; Topological Entropy; Total Variation; Fourier Coefficients.
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APA (6th Edition):
Roque Sol, M. A. (2009). A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1810
Chicago Manual of Style (16th Edition):
Roque Sol, Marco A. “A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-1810.
MLA Handbook (7th Edition):
Roque Sol, Marco A. “A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps.” 2009. Web. 04 Mar 2021.
Vancouver:
Roque Sol MA. A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1810.
Council of Science Editors:
Roque Sol MA. A study of the sensitivity of topological dynamical systems and the Fourier spectrum of chaotic interval maps. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1810
Texas A&M University
26.
Bello, Rasheed O.
Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior.
Degree: PhD, Petroleum Engineering, 2010, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-316
► Many hydraulically fractured shale gas horizontal wells in the Barnett shale have been observed to exhibit transient linear behavior. This transient linear behavior is characterized…
(more)
▼ Many hydraulically fractured shale gas horizontal wells in the Barnett shale have been
observed to exhibit transient linear behavior. This transient linear behavior is
characterized by a one-half slope on a log-log plot of rate against time. This transient
linear flow regime is believed to be caused by transient drainage of low permeability
matrix blocks into adjoining fractures. This transient flow regime is the only flow regime
available for analysis in many wells.
The hydraulically fractured shale gas reservoir system was described in this work
by a linear dual porosity model. This consisted of a bounded rectangular reservoir with
slab matrix blocks draining into adjoining fractures and subsequently to a horizontal well
in the centre. The horizontal well fully penetrates the rectangular reservoir. Convergence
skin is incorporated into the linear model to account for the presence of the horizontal
wellbore.
Five flow regions were identified with this model. Region 1 is due to transient
flow only in the fractures. Region 2 is bilinear flow and occurs when the matrix drainage
begins simultaneously with the transient flow in the fractures. Region 3 is the response for a homogeneous reservoir. Region 4 is dominated by transient matrix drainage and is
the transient flow regime of interest. Region 5 is the boundary dominated transient
response. New working equations were developed and presented for analysis of Regions
1 to 4. No equation was presented for Region 5 as it requires a combination of material
balance and productivity index equations beyond the scope of this work.
It is concluded that the transient linear region observed in field data occurs in
Region 4 – drainage of the matrix. A procedure is presented for analysis. The only
parameter that can be determined with available data is the matrix drainage area, Acm.
It was also demonstrated in this work that the effect of skin under constant rate
and constant bottomhole pressure conditions is not similar for a linear reservoir. The
constant rate case is the usual parallel lines with an offset but the constant bottomhole
pressure shows a gradual diminishing effect of skin. A new analytical equation was
presented to describe the constant bottomhole pressure effect of skin in a linear
reservoir.
It was also demonstrated that different shape factor formulations (Warren and
Root, Zimmerman and Kazemi) result in similar Region 4 transient linear response
provided that the appropriate f(s) modifications consistent with lAc calculations are
conducted. It was also demonstrated that different matrix geometry exhibit the same
Region 4 transient linear response when the area-volume ratios are similar.
Advisors/Committee Members: Wattenbarger, Robert (committee member), Ehlig-Economides, Christine (committee member), Chen, Goong (committee member).
Subjects/Keywords: Transient Linear; Shale Gas; Dual Porosity, Horizontal Wells, Fractured Reservoirs, Multi-fractured
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MLA ·
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CSE |
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to Zotero / EndNote / Reference
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APA (6th Edition):
Bello, R. O. (2010). Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-316
Chicago Manual of Style (16th Edition):
Bello, Rasheed O. “Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior.” 2010. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-316.
MLA Handbook (7th Edition):
Bello, Rasheed O. “Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior.” 2010. Web. 04 Mar 2021.
Vancouver:
Bello RO. Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior. [Internet] [Doctoral dissertation]. Texas A&M University; 2010. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-316.
Council of Science Editors:
Bello RO. Rate Transient Analysis in Shale Gas Reservoirs with Transient Linear Behavior. [Doctoral Dissertation]. Texas A&M University; 2010. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-316
Texas A&M University
27.
Wang, Ling.
Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter.
Degree: PhD, Physics, 2008, Texas A&M University
URL: http://hdl.handle.net/1969.1/85959
► The integrating cavity absorption meter (ICAM) has been used successfully to measure the low absorption coefficient of pure water. The ICAM produces an effective total…
(more)
▼ The integrating cavity absorption meter (ICAM) has been used successfully to measure
the low absorption coefficient of pure water. The ICAM produces an effective total path
length of several meters or even longer, although the physical size of the instrument is
only several centimeters. The long effective total path length ensures a high sensitivity
that enables the ICAM to measure liquid mediums with low absorption. Compared to the
conventional transmission type of instruments that were used to measure the same
medium with the same path length, the ICAM eliminates the effect of scattering by
introducing isotropic illumination in the medium, and consequently measures the true
absorption coefficient of the medium in stead of the attenuation coefficient. The original
ICAM was constructed with Spectralon and used in the wavelength range from 380 nm
to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the
UV region because of its relatively lower reflectivity in this region and, even worse, the
continuously decaying reflectivity under the exposure to UV radiation. Thus, we have
developed a new way to construct the ICAM utilizing the material fumed silica. The resulting ICAM has a high sensitivity even in the UV region and doesn't have the
deterioration problem. The measurement results from the new ICAM are in good
agreement with the existing results. The absorption coefficients of pure water at
wavelengths between 250 nm and 400 nm are presented here.
Advisors/Committee Members: Fry, Edward S. (advisor), Kenefick, Robert A. (committee member), Sokolov, Alexei (committee member), Chen, Goong (committee member).
Subjects/Keywords: Integrating cavity absorption meter; Pure water absorption
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Wang, L. (2008). Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/85959
Chicago Manual of Style (16th Edition):
Wang, Ling. “Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter.” 2008. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/85959.
MLA Handbook (7th Edition):
Wang, Ling. “Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter.” 2008. Web. 04 Mar 2021.
Vancouver:
Wang L. Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter. [Internet] [Doctoral dissertation]. Texas A&M University; 2008. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/85959.
Council of Science Editors:
Wang L. Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter. [Doctoral Dissertation]. Texas A&M University; 2008. Available from: http://hdl.handle.net/1969.1/85959
Texas A&M University
28.
Chen, Xianjin.
Analysis and computation of multiple unstable solutions to nonlinear elliptic systems.
Degree: PhD, Mathematics, 2009, Texas A&M University
URL: http://hdl.handle.net/1969.1/ETD-TAMU-2990
► We study computational theory and methods for finding multiple unstable solutions (corresponding to saddle points) to three types of nonlinear variational elliptic systems: cooperative, noncooperative,…
(more)
▼ We study computational theory and methods for finding multiple unstable solutions
(corresponding to saddle points) to three types of nonlinear variational elliptic
systems: cooperative, noncooperative, and Hamiltonian. We first propose a new Lorthogonal
selection in a product Hilbert space so that a solution manifold can be
defined. Then, we establish, respectively, a local characterization for saddle points of
finite Morse index and of infinite Morse index. Based on these characterizations, two
methods, called the local min-orthogonal method and the local min-max-orthogonal
method, are developed and applied to solve those three types of elliptic systems for
multiple solutions. Under suitable assumptions, a subsequence convergence result
is established for each method. Numerical experiments for different types of model
problems are carried out, showing that both methods are very reliable and efficient in
computing coexisting saddle points or saddle points of infinite Morse index. We also
analyze the instability of saddle points in both single and product Hilbert spaces. In
particular, we establish several estimates of the Morse index of both coexisting and
non-coexisting saddle points via the local min-orthogonal method developed and propose
a local instability index to measure the local instability of both degenerate and
nondegenerate saddle points. Finally, we suggest two extensions of an L-orthogonal
selection for future research so that multiple solutions to more general elliptic systems
such as nonvariational elliptic systems may also be found in a stable way.
Advisors/Committee Members: Zhou, Jianxin (advisor), Chen, Goong (committee member), Chin, Siu A. (committee member), Efendiev, Yalchin (committee member), Kuchment, Peter (committee member).
Subjects/Keywords: Multiple solutions; Saddle point computation; Variational elliptic
systems; Min-orthogonal method; Min-max-orthogonal method
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Chen, X. (2009). Analysis and computation of multiple unstable solutions to nonlinear elliptic systems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2990
Chicago Manual of Style (16th Edition):
Chen, Xianjin. “Analysis and computation of multiple unstable solutions to nonlinear elliptic systems.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/ETD-TAMU-2990.
MLA Handbook (7th Edition):
Chen, Xianjin. “Analysis and computation of multiple unstable solutions to nonlinear elliptic systems.” 2009. Web. 04 Mar 2021.
Vancouver:
Chen X. Analysis and computation of multiple unstable solutions to nonlinear elliptic systems. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2990.
Council of Science Editors:
Chen X. Analysis and computation of multiple unstable solutions to nonlinear elliptic systems. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2990
Texas A&M University
29.
Xiong, Han.
Coherence-induced entanglement.
Degree: PhD, Physics, 2006, Texas A&M University
URL: http://hdl.handle.net/1969.1/3797
► Coherence and entanglement are the two key concepts that distinguish quantum mechanics from classical mechanics. Many novel phenomena occuring in the quantum world are due…
(more)
▼ Coherence and entanglement are the two key concepts that distinguish quantum
mechanics from classical mechanics. Many novel phenomena occuring in the quantum
world are due to these two Âphysical quantitiesÂ. They also play essential roles in
quantum computation and quantum information. For example, coherence, which
says that a quantum mechanical system could be in a superposition state, makes the
quantum parallel computing scheme possible; and entanglement, which says that two
quantum systems separated in space could be in an intervened state, is the key factor
in various quantum teleportation algorithms.
We have studied entanglement generation in various systems. We found that with
atomic coherence, entanglement could be generated between two thermal fields with
arbitrarily high temperatures. We also found that temperature difference instead of
the purity of state is essential for the entanglement generation between an atom and
a thermal field. We discovered that correlated spontaneous emission lasers (CELs)
could be used to generate bright entanglement laser beams. As a special case of CEL
systems, we studied entanglement generation in Non-degenerate Optical Parametric
Amplifiers (NOPAs). We performed the input-output calculations for a NOPA system
and showed that the two output optical beams are still entangled. This justifies our idea that CEL (or NOPA) systems can be used as an ideal entanglement source
for various quantum information schemes. From an experimental point of view, we
considered the effects of pumping fluctuations on entanglement generation in CEL
and NOPA systems. We found that these fluctuations, especially the phase diffusion
processes, in the pump laser would greatly reduce the entanglement generated in such
systems.
Advisors/Committee Members: Scully, Marlan O. (advisor), Zubairy, M. Suhail (advisor), Chen, Goong (committee member), Welch, George R. (committee member).
Subjects/Keywords: Quantum Information; Entanglement
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APA (6th Edition):
Xiong, H. (2006). Coherence-induced entanglement. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/3797
Chicago Manual of Style (16th Edition):
Xiong, Han. “Coherence-induced entanglement.” 2006. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/3797.
MLA Handbook (7th Edition):
Xiong, Han. “Coherence-induced entanglement.” 2006. Web. 04 Mar 2021.
Vancouver:
Xiong H. Coherence-induced entanglement. [Internet] [Doctoral dissertation]. Texas A&M University; 2006. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/3797.
Council of Science Editors:
Xiong H. Coherence-induced entanglement. [Doctoral Dissertation]. Texas A&M University; 2006. Available from: http://hdl.handle.net/1969.1/3797
Texas A&M University
30.
Yan, Hui.
Dynamics and real-time optimal control of satellite attitude and satellite formation systems.
Degree: PhD, Aerospace Engineering, 2006, Texas A&M University
URL: http://hdl.handle.net/1969.1/4283
► In this dissertation the solutions of the dynamics and real-time optimal control of magnetic attitude control and formation flying systems are presented. In magnetic attitude…
(more)
▼ In this dissertation the solutions of the dynamics and real-time optimal control of
magnetic attitude control and formation flying systems are presented. In magnetic
attitude control, magnetic actuators for the time-optimal rest-to-rest maneuver with a
pseudospectral algorithm are examined. The time-optimal magnetic control is bang-bang
and the optimal slew time is about 232.7 seconds. The start time occurs when the
maneuver is symmetric about the maximum field strength. For real-time computations,
all the tested samples converge to optimal solutions or feasible solutions. We find the
average computation time is about 0.45 seconds with the warm start and 19 seconds with
the cold start, which is a great potential for real-time computations. Three-axis magnetic
attitude stabilization is achieved by using a pseudospectral control law via the receding
horizon control for satellites in eccentric low Earth orbits. The solutions from the
pseudospectral control law are in excellent agreement with those obtained from the
Riccati equation, but the computation speed improves by one order of magnitude. Numerical solutions show state responses quickly tend to the region where the attitude
motion is in the steady state.
Approximate models are often used for the study of relative motion of formation
flying satellites. A modeling error index is introduced for evaluating and comparing the
accuracy of various theories of the relative motion of satellites in order to determine the
effect of modeling errors on the various theories. The numerical results show the
sequence of the index from high to low should be Hill's equation, non- J2, small
eccentricity, Gim-Alfriend state transition matrix index, with the unit sphere approach
and the Yan-Alfriend nonlinear method having the lowest index and equivalent
performance. A higher order state transition matrix is developed using unit sphere
approach in the mean elements space. Based on the state transition matrix analytical
control laws for formation flying maintenance and reconfiguration are proposed using
low-thrust and impulsive scheme. The control laws are easily derived with high
accuracy. Numerical solutions show the control law works well in real-time
computations.
Advisors/Committee Members: Alfriend, Kyle T. (advisor), Chen, Goong (committee member), Junkins, John L. (committee member), Vadali, Srinivas R. (committee member).
Subjects/Keywords: Optimal Control; Real-Time; Formation Flying; Magnetic Attitude Control; Pseudospectral Methods
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Yan, H. (2006). Dynamics and real-time optimal control of satellite attitude and satellite formation systems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/4283
Chicago Manual of Style (16th Edition):
Yan, Hui. “Dynamics and real-time optimal control of satellite attitude and satellite formation systems.” 2006. Doctoral Dissertation, Texas A&M University. Accessed March 04, 2021.
http://hdl.handle.net/1969.1/4283.
MLA Handbook (7th Edition):
Yan, Hui. “Dynamics and real-time optimal control of satellite attitude and satellite formation systems.” 2006. Web. 04 Mar 2021.
Vancouver:
Yan H. Dynamics and real-time optimal control of satellite attitude and satellite formation systems. [Internet] [Doctoral dissertation]. Texas A&M University; 2006. [cited 2021 Mar 04].
Available from: http://hdl.handle.net/1969.1/4283.
Council of Science Editors:
Yan H. Dynamics and real-time optimal control of satellite attitude and satellite formation systems. [Doctoral Dissertation]. Texas A&M University; 2006. Available from: http://hdl.handle.net/1969.1/4283
◁ [1] [2] ▶
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Open Access Theses and Dissertations
