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Articles 31 - 60 of 131
Full-Text Articles in Physical Sciences and Mathematics
Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99M⊙ and total masses of 25-100M⊙. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19M⊙ …
Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ∼1kpc from Earth, an order of magnitude …
Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta
Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta
Physics Faculty Research & Creative Works
We study the ferromagnetic phase transition in a randomly layered Heisenberg model. A recent strong-disorder renormalization group approach [Phys. Rev. B 81, 144407 (2010)] predicted that the critical point in this system is of exotic infinite-randomness type and is accompanied by strong power-law Griffiths singularities. Here, we report results of Monte-Carlo simulations that provide numerical evidence in support of these predictions. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility which is characterized by a non-universal power-law divergence in the Griffiths phase. In addition, we calculate the time autocorrelation function of the spins. It features a very slow …
Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province: Results From Receiver Function And Gravity Studies, Lamuail Bashir, Stephen S. Gao, Kelly H. Liu, Kevin Lee Mickus
Crustal Structure And Evolution Beneath The Colorado Plateau And The Southern Basin And Range Province: Results From Receiver Function And Gravity Studies, Lamuail Bashir, Stephen S. Gao, Kelly H. Liu, Kevin Lee Mickus
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Over the past several decades, contrasting models have been proposed for the physical and chemical processes responsible for the uplift and long-term stability of the Colorado Plateau (CP) and crustal thinning beneath the Basin and Range Province (BRP) in the southwestern United States. Here we provide new constraints on the models by modeling gravity anomalies and by systematically analyzing over 15,500 P-to-S receiver functions recorded at 72 USArray and other broadband seismic stations on the southwestern CP and the southern BRP. Our results reveal that the BRP is characterized by a thin crust (28.2 ± 0.5 km), a mean V …
A Range And Existence Theorem For Pseudomonotone Perturbations Of Maximal Monotone Operators, Vy Khoi Le
A Range And Existence Theorem For Pseudomonotone Perturbations Of Maximal Monotone Operators, Vy Khoi Le
Mathematics and Statistics Faculty Research & Creative Works
In this paper, we prove a range and existence theorem for multivalued pseudomonotone perturbations of maximal monotone operators. We assume a general coercivity condition on the sum of a maximal monotone and a pseudomonotone operator instead of a condition on the pseudomonotone operator only. An illustrative example of a variational inequality in a Sobolev space with variable exponent is given.
Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley
Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley
Physics Faculty Research & Creative Works
We report a parametrization of a previous self-consistent tight-binding model, suitable for metals with a high atomic number in which nonscalar-relativistic effects are significant in the electron physics of condensed phases. The method is applied to platinum. The model is fitted to density functional theory band structures and cohesive energies and spectroscopic data on platinum atoms in five oxidation states, and is then shown without further parametrization to correctly reproduce several low index surface structures. We also predict reconstructions of some vicinal surfaces.
Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We report theoretical calculations of the effect of the multiple-orbital contribution in high-order harmonic generation (HHG) of aligned CO₂ with the inclusion of macroscopic propagation of harmonic fields in the medium. Our results show very good agreement with recent experiments for the dynamics of the minimum in HHG spectra as laser intensity or alignment angle changes. Calculations are carried out to check how the position of the minimum in HHG spectra depends on the degrees of molecular alignment, laser-focusing conditions, and the effects of alignment-dependent ionization rates of the different molecular orbitals. These analyses help to explain why the minima …
Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison
Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison
Physics Faculty Research & Creative Works
Low energy experimental and theoretical triply differential cross sections are presented for electron impact ionization of methane (CH4) for both the highest occupied molecular orbital (HOMO) and next highest occupied molecular orbital (NHOMO). The HOMO is a predominantly p-type orbital which is labeled 1t2 and the NHOMO is predominantly s-type labeled 2a 1. Coplanar symmetric (symmetric both in final state electron energies and observation angles) are presented for final state electron energies ranging from 2.5 to 20 eV. The theoretical M3DW (molecular three-body distorted wave) results are in surprisingly good agreement with experiment for the HOMO …
Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura
Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Zα, where Z is the nuclear-charge number and α is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13≤n≤16, and orbital angular momenta =n-2 and =n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with ≥2 and arbitrary n, , and total angular momentum j. The low-energy contributions …
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Chemistry Faculty Research & Creative Works
The magnetic, electronic, and Mössbauer spectral properties of Fe 2L(µ-OAc)2ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm-1 for an …
Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi
Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi
Physics Faculty Research & Creative Works
Baryon acoustic oscillations imprinted in the galaxy power spectrum can be used as a standard ruler to determine the angular diameter distance and Hubble parameter from high-redshift galaxies. Combining redshift distortion effect which apparently distorts the galaxy clustering pattern, we can also constrain the growth rate of large-scale structure formation. Usually, future forecasts for constraining these parameters from galaxy redshift surveys are made with the full 2D power spectrum characterized as a function of wave number k and directional cosine µ between line-of-sight direction and wave vector, i.e., P(k,µ). Here, we apply the multipole expansion to the full 2D power …
Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch
Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch
Physics Faculty Research & Creative Works
We analyze and review the theory of the hydrogen-deuterium isotope shift for the 1S-2S transition, which is one of the most accurately measured isotope shifts in any atomic system, in view of a recently improved experiment. A tabulation of all physical effects that contribute to the isotope shift is given. These include the Dirac binding energy, quantum electrodynamic effects, including recoil corrections, and the nuclear-size effect, including the pertaining relativistic and radiative corrections. From a comparison of the theoretical result Δfth=670999566.90(66)(60)kHz (exclusive of the nonrelativistic nuclear-finite-size correction) and the experimental result Δfexpt=670994334605(15) Hz, we infer the …
Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito
Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito
Physics Faculty Research & Creative Works
Proposed space-based gravitational-wave detectors such as BBO and DECIGO can detect ~ 106 neutron star (NS) binaries and determine the luminosity distance to the binaries with high precision. Combining the luminosity distance and electromagnetically derived redshift, one would be able to probe cosmological expansion out to high redshift. In this paper, we show that the Hubble parameter as a function of redshift can be directly measured with monopole and dipole components of the luminosity distance on the sky. As a result, the measurement accuracies of the Hubble parameter in each redshift bin up to z=1 are 3-14%, 1.5-8%, and …
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric …
Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz
Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz
Physics Faculty Research & Creative Works
We have measured the scattering angle dependence of cross sections for ionization in p+H2 collisions for a fixed projectile energy loss. Depending on the projectile coherence, interference due to indistinguishable diffraction of the projectile from the two atomic centers was either present or absent in the data. This shows that, due to the fundamentals of quantum mechanics, the preparation of the beam must be included in theoretical calculations. The results have far-reaching implications on formal atomic scattering theory because this critical aspect has been overlooked for several decades.
High-Order-Harmonic Generation Using Gas-Phase H₂O Molecules, Song-Feng Zhao, Cheng Jin, R. R. Lucchese, Anh-Thu Le, C. D. Lin
High-Order-Harmonic Generation Using Gas-Phase H₂O Molecules, Song-Feng Zhao, Cheng Jin, R. R. Lucchese, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We investigate high-order-harmonic generation of isotropically distributed gas-phase H₂O molecules exposed to an intense laser field. The induced dipole of each individual molecule by the laser field is first calculated using the recently developed quantitative rescattering theory. In a thin medium, harmonic spectra generated coherently from all the molecules are then calculated by solving Maxwell's equation of propagation. By using accurate transition dipoles of H₂O, we show that the harmonics in the lower plateau region are quite different from models that employ the simpler strong-field approximation. We also examine the magnitude and phase of the harmonics and their dependence on …
Differential Cross Sections For Single Ionization Of H₂ By 75-Kev Proton Impact, Ujjal Chowdhury, Michael Schulz, Don H. Madison
Differential Cross Sections For Single Ionization Of H₂ By 75-Kev Proton Impact, Ujjal Chowdhury, Michael Schulz, Don H. Madison
Physics Faculty Research & Creative Works
We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H2 by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H2 as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the …
Compton Upconversion Of Twisted Photons: Backscattering Of Particles With Non-Planar Wave Functions, Ulrich D. Jentschura, Valery G. Serbo
Compton Upconversion Of Twisted Photons: Backscattering Of Particles With Non-Planar Wave Functions, Ulrich D. Jentschura, Valery G. Serbo
Physics Faculty Research & Creative Works
Twisted photons are not plane waves, but superpositions of plane waves with a defined projection hm of the orbital angular momentum onto the propagation axis (m is integer and may attain values m≫ 1). Here, we describe in detail the possibility to produce high-energy twisted photons by backward Compton scattering of twisted laser photons on ultra-relativistic electrons with a Lorentz-factor γ=E/(mec2)≫ 1. When a twisted laser photon with the energy hω~1 eV performs a collision with an electron and scatters backward, the final twisted photon conserves the angular momentum m, but its energy hω' is increased …
Search For Gravitational Waves Associated With The August 2006 Timing Glitch Of The Vela Pulsar, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Waves Associated With The August 2006 Timing Glitch Of The Vela Pulsar, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission. In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational-wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. …
Petrographic Comparison And Contrast Of Fluvial And Deltaic Sandstones, Upper Pennsylvanian Oread Cyclothem, Ne Oklahoma, Jonathan Obrist-Farner, Wan Yang
Petrographic Comparison And Contrast Of Fluvial And Deltaic Sandstones, Upper Pennsylvanian Oread Cyclothem, Ne Oklahoma, Jonathan Obrist-Farner, Wan Yang
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
Upper Pennsylvanian sandstones have been the target in petroleum exploration and production in Kansas and Oklahoma. However, the petrographic characteristics of these sandstones have been rarely reported. A good understanding of the characteristics and depositional environments of those sandstones will help explore the correlative subsurface petroleum reservoirs efficiently.
Neutrino Mass Constraint From The Sloan Digital Sky Survey Power Spectrum Of Luminous Red Galaxies And Perturbation Theory, Shun Saito, Masahiro Takada, Atsushi Taruya
Neutrino Mass Constraint From The Sloan Digital Sky Survey Power Spectrum Of Luminous Red Galaxies And Perturbation Theory, Shun Saito, Masahiro Takada, Atsushi Taruya
Physics Faculty Research & Creative Works
We compare the model power spectrum, computed based on perturbation theory, with the power spectrum of luminous red galaxies (LRG) measured from the Sloan Digital Sky Survey Data Release 7 catalog, assuming a flat, cold dark matter-dominated cosmology. The model includes the effects of massive neutrinos, nonlinear matter clustering and nonlinear, scale-dependent galaxy bias in a self-consistent manner. We first test the accuracy of the perturbation theory model by comparing the model predictions with the halo power spectrum in real- and redshift-space, measured from 70 simulation realizations for a cold dark matter model without massive neutrinos. We show that the …
Observation Of Strong Resonant Behavior In The Inverse Photoelectron Spectroscopy Of Ce Oxide, James G. Tobin, Sw Yu, Brandon W. Chung, George Daniel Waddill, Laurent Claudius Duda, Joseph S. Nordgren
Observation Of Strong Resonant Behavior In The Inverse Photoelectron Spectroscopy Of Ce Oxide, James G. Tobin, Sw Yu, Brandon W. Chung, George Daniel Waddill, Laurent Claudius Duda, Joseph S. Nordgren
Physics Faculty Research & Creative Works
X-ray emission spectroscopy and resonant inverse photoelectron spectroscopy (RIPES) have been used to investigate the photon emission associated with the Ce 3d5/2 and Ce 3d3/2 thresholds. Strong resonant behavior has been observed in the RIPES of a Ce oxide near the 5/2 and 3/2 edges.
Medium Propagation Effects In High-Order Harmonic Generation Of Ar And N₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Medium Propagation Effects In High-Order Harmonic Generation Of Ar And N₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We report theoretical calculations of high-order harmonic generation (HHG) by intense infrared lasers in atomic and molecular targets taking into account the macroscopic propagation of both fundamental and harmonic fields. On the examples of Ar and N₂, we demonstrate that these ab initio calculations are capable of accurately reproducing available experimental results with isotropic and aligned target media. We further present detailed analysis of HHG intensity and phase under various experimental conditions, in particular, as the wavelength of the driving laser changes. Most importantly, our results strongly support the factorization of HHG at the macroscopic level into a product of …
Plastic Packaging: A Current Perspective On Sustainability, Shristy Bashyal, Bonnie Bachman, Margaret H. Baumann
Plastic Packaging: A Current Perspective On Sustainability, Shristy Bashyal, Bonnie Bachman, Margaret H. Baumann
Business and Information Technology Faculty Research & Creative Works
Packaging producers, machine manufacturers, and/or resin manufacturers are studied to conduct case study research to assess the issues they are facing with regard to “sustainability”. This industry viewpoint is conducted to generate information regarding environmental pressures facing these companies and the resulting strategies employed to be competitive and sustainable. To collect the necessary information about these selected companies and the overall industry point of view they represent, direct interview techniques are used.
Balanced Pod For Model Reduction Of Linear Pde Systems: Convergence Theory, John R. Singler
Balanced Pod For Model Reduction Of Linear Pde Systems: Convergence Theory, John R. Singler
Mathematics and Statistics Faculty Research & Creative Works
We consider convergence analysis for a model reduction algorithm for a class of linear infinite dimensional systems. The algorithm computes an approximate balanced truncation of the system using solution snapshots of specific linear infinite dimensional differential equations. The algorithm is related to the proper orthogonal decomposition, and it was first proposed for systems of ordinary differential equations by Rowley (Int. J. Bifurc. Chaos Appl. Sci. Eng. 15(3), 997-1013, 2005). For the convergence analysis, we consider the algorithm in terms of the Hankel operator of the system, rather than the product of the system Gramians as originally proposed by Rowley. For …
Balanced Pod For Linear Pde Robust Control Computations, John R. Singler, Belinda A. Batten
Balanced Pod For Linear Pde Robust Control Computations, John R. Singler, Belinda A. Batten
Mathematics and Statistics Faculty Research & Creative Works
A mathematical model of a physical system is never perfect; therefore, robust control laws are necessary for guaranteed stabilization of the nominal model and also "nearby" systems, including hopefully the actual physical system. We consider the computation of a robust control law for large-scale nite dimensional linear systems and a class of linear distributed parameter systems. The controller is robust with respect to left coprime factor perturbations of the nominal system. We present an algorithm based on balanced proper orthogonal decomposition to compute the nonstandard features of this robust control law. Convergence theory is given, and numerical results are presented …
A Model Based Feedback Controller For Wing-Twist Via Piezoceramic Actuation, John R. Singler, Belinda A. Batten
A Model Based Feedback Controller For Wing-Twist Via Piezoceramic Actuation, John R. Singler, Belinda A. Batten
Mathematics and Statistics Faculty Research & Creative Works
In this paper we present a model for a rubber plate with piezoceramic actuators to represent a bioinspired flexible wing. Using a Galerkin based finite element approximation to the system, we compute a linear quadratic based tracking control for piezoelectric actuators placed along both leading and trailing edges. Using these piezoceramic devices, we demonstrate the effectiveness of model based feedback control in achieving a desired wing tip position; this modified shape is analogous to aircraft roll moment generation via wing twist.
Convergent Snapshot Algorithms For Infinite-Dimensional Lyapunov Equations, John R. Singler
Convergent Snapshot Algorithms For Infinite-Dimensional Lyapunov Equations, John R. Singler
Mathematics and Statistics Faculty Research & Creative Works
We consider two algorithms to approximate the solution Z of a class of stable operator Lyapunov equations of the form AZ + ZA* + BB* = 0. The algorithms utilize time snapshots of solutions of certain linear infinite-dimensional differential equations to construct the approximations. Matrix approximations of the operators a and B are not required and the algorithms are applicable as long as the rank of B is relatively small. The first algorithm produces an optimal low-rank approximate solution using proper orthogonal decomposition. The second algorithm approximates the product of the solution with a few vectors and can be implemented …
Sub-Supersolution Method In Variational Inequalities With Multivalued Operators Given By Integrals, Vy Khoi Le
Sub-Supersolution Method In Variational Inequalities With Multivalued Operators Given By Integrals, Vy Khoi Le
Mathematics and Statistics Faculty Research & Creative Works
No abstract provided.
Receiver Function Studies Of Crustal Structure, Composition, And Evolution Beneath The Afar Depression, Ethiopia, Sattam A. Almadani
Receiver Function Studies Of Crustal Structure, Composition, And Evolution Beneath The Afar Depression, Ethiopia, Sattam A. Almadani
Doctoral Dissertations
"The dissertation utilizes a set of sophisticated computer programs developed at the Geophysics group at Missouri S&T to characterize crustal properties beneath the Afar Depression in Ethiopia where extensional tectonics dominates. In this study, measurements of crustal thickness (H), crustal mean Vp/Vs [which is related to Poisson's ratio (Σ)], and the sharpness of the Moho (R) were determined using teleseismic data from 18 broadband seismic sensors that we deployed along a profile of 250 km long with a station spacing of ~ 10 km. The stations had been recording continuously for an entire year from December 2009 until December 2010. …