Proceedings of the 2010 Conference of the Center for Advanced Studies on Collaborative Research - CASCON '10, 2010
ABSTRACT Problem determination in a database management system can be a difficult task given the ... more ABSTRACT Problem determination in a database management system can be a difficult task given the complexity of the system and the large amount of data that must be collected and analyzed. Monitoring the system for this data incurs overhead and has a detrimental effect on application performance. As an alternative to the standard practice of storing the performance data and performing offline analysis, we examine an approach where monitoring data is produced as a continuous data stream and data stream mining techniques are applied. We implement this approach as a prototype system called Tempo on IBM DB2®. Tempo implements Top-K analysis, which is a common task performed by database administrators for problem determination. Top-K analysis typically identifies the set of most frequently occurring events, or the highest consumers of system resources. Our experimental evaluation indicates that Tempo is time and space efficient, incurs low overhead, and produces accurate results.
ABSTRACT Doubly excited states (DES) of heliumlike systems are studied within the coupled-channel... more ABSTRACT Doubly excited states (DES) of heliumlike systems are studied within the coupled-channel hyperspherical adiabatic approach. The results of the multichannel calculations of the 1Se and 1Po DES of H- and He converging to the second (n=2) threshold are presented and compared with those found in literature.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1989
ABSTRACT The convergence of the hyperspherical adiabatic expansion for helium-like systems has be... more ABSTRACT The convergence of the hyperspherical adiabatic expansion for helium-like systems has been studied numerically. The spectral problems arising after approximate separation of variables are solved by the finite-difference and finite-element methods. The energies of the ground and some doubly excited states of the negative hydrogen ion are calculated in the six-channel approximation within 10-4 au accuracy. The results obtained demonstrate a rapid convergence of the hyperspherical adiabatic expansion and agree reasonably well with experimental data as well as with other more complicated theoretical calculations.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1991
ABSTRACT The analytical properties of the scattering matrix in the adiabatic formulation of the m... more ABSTRACT The analytical properties of the scattering matrix in the adiabatic formulation of the multichannel scattering problem in a three-body system are investigated as functions of the coupling constant and energy in the framework of the adiabatic hyperspherical approach. The localization and the character of pole motion in the complex coupling constant plane and on the Riemann energy surface are studied. On this basis a method for obtaining the resonant state parameters by extrapolation in the coupling constant using Pade approximants of the second type is suggested. The developed approach is applied to calculate the position and width of the 1Po shape resonance in the e--H scattering. The position Er=0.015 eV and width Gamma r=0.012 eV of the H- 1Po shape resonance calculated in the simple one-channel adiabatic approximation are in good agreement with other theoretical calculations.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1991
The hyperspherical adiabatic (HSA) representation is introduced in barycentric coordinates for he... more The hyperspherical adiabatic (HSA) representation is introduced in barycentric coordinates for helium-like systems in which isotopic and correlation effects are taken into account exactly. Different methods of forming the HSA basis are considered. The general classification of the HSA basis states is suggested, and examples of correlation diagrams are presented. The complete classification of doubly excited states of two-electron systems
Theory of two-photon ionization via intermediate dissociative states is developed. The theory is ... more Theory of two-photon ionization via intermediate dissociative states is developed. The theory is applied to the one-color two-photon ionization of CH3I for which the 3Q0 and 1Q1 dissociative states serve as intermediate resonances. Both CW and transient ionization spectra are calculated. The computed methyl iodide CW ionization line intensities are in profound disagreement with line intensities derived from two-photon zero
Control over the product branching ratio in the photodissociation of Li2 into Li(2s)+Li(2p) and L... more Control over the product branching ratio in the photodissociation of Li2 into Li(2s)+Li(2p) and Li(2s)+Li(3p) channels is explored computationally using the pump-pump coherent control scenario. Extensive control over the Li(3p)/Li(2p) branching ratio is demonstrated as the delay time between the two pulses is varied. The pulse width dependence is examined and better control is found to result from a narrow
We present an application of ‘‘optimal squeezing’’ theory to the design of laser pulses for gener... more We present an application of ‘‘optimal squeezing’’ theory to the design of laser pulses for generation of squeezed states of material waves (states whose localization in some variable exceeds that of the ground state) in Na2. Spatiotemporal evolution of the squeezed states during and after the laser pulse is studied. We show that the optimized laser pulses can affect squeezing
Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2B... more Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2Br+I or CH2I+Br is examined computationally. Quantum photodissociation calculations, using two excited potentials surfaces, are carried out using a new method incorporating negative imaginary absorbing potentials within the artificial channel method. Extensive control over the I/Br branching ratio is shown to result as experimentally controllable laser amplitudes
ABSTRACT A FORTRAN program is presented which solves the Sturm-Liouville problem for a system of ... more ABSTRACT A FORTRAN program is presented which solves the Sturm-Liouville problem for a system of coupled second-order differential equations by the finite difference method of the second order using the iterative Richardson extrapolation of the difference eigensolutions on a sequence of doubly condensed meshes. The same extrapolational procedure and error estimations are applied to the eigenvalues and eigenfunctions. Zero-value (Dirichlet) or zero-gradient (Neumann) boundary conditions are considered. (C) 1998 Elsevier Science B.V.
A method for numerical solution of the coupled-channel Schrödinger equation for bound states base... more A method for numerical solution of the coupled-channel Schrödinger equation for bound states based on the finite-difference method of the second order with iterative extrapolation of net eigensolutions is described. It is shown that Richardson's extrapolation to the limit significantly increases the accuracy of the finite-difference solutions with substantial reduction of requirements in computer memory, disk storage and computational time.
Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2B... more Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2Br+I or CH2I+Br is examined computationally. Quantum photodissociation calculations, using two excited potentials surfaces, are carried out using a new method incorporating negative imaginary absorbing potentials within the artificial channel method. Extensive control over the I/Br branching ratio is shown to result as experimentally controllable laser amplitudes
Proceedings of the 2010 Conference of the Center for Advanced Studies on Collaborative Research - CASCON '10, 2010
ABSTRACT Problem determination in a database management system can be a difficult task given the ... more ABSTRACT Problem determination in a database management system can be a difficult task given the complexity of the system and the large amount of data that must be collected and analyzed. Monitoring the system for this data incurs overhead and has a detrimental effect on application performance. As an alternative to the standard practice of storing the performance data and performing offline analysis, we examine an approach where monitoring data is produced as a continuous data stream and data stream mining techniques are applied. We implement this approach as a prototype system called Tempo on IBM DB2®. Tempo implements Top-K analysis, which is a common task performed by database administrators for problem determination. Top-K analysis typically identifies the set of most frequently occurring events, or the highest consumers of system resources. Our experimental evaluation indicates that Tempo is time and space efficient, incurs low overhead, and produces accurate results.
ABSTRACT Doubly excited states (DES) of heliumlike systems are studied within the coupled-channel... more ABSTRACT Doubly excited states (DES) of heliumlike systems are studied within the coupled-channel hyperspherical adiabatic approach. The results of the multichannel calculations of the 1Se and 1Po DES of H- and He converging to the second (n=2) threshold are presented and compared with those found in literature.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1989
ABSTRACT The convergence of the hyperspherical adiabatic expansion for helium-like systems has be... more ABSTRACT The convergence of the hyperspherical adiabatic expansion for helium-like systems has been studied numerically. The spectral problems arising after approximate separation of variables are solved by the finite-difference and finite-element methods. The energies of the ground and some doubly excited states of the negative hydrogen ion are calculated in the six-channel approximation within 10-4 au accuracy. The results obtained demonstrate a rapid convergence of the hyperspherical adiabatic expansion and agree reasonably well with experimental data as well as with other more complicated theoretical calculations.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1991
ABSTRACT The analytical properties of the scattering matrix in the adiabatic formulation of the m... more ABSTRACT The analytical properties of the scattering matrix in the adiabatic formulation of the multichannel scattering problem in a three-body system are investigated as functions of the coupling constant and energy in the framework of the adiabatic hyperspherical approach. The localization and the character of pole motion in the complex coupling constant plane and on the Riemann energy surface are studied. On this basis a method for obtaining the resonant state parameters by extrapolation in the coupling constant using Pade approximants of the second type is suggested. The developed approach is applied to calculate the position and width of the 1Po shape resonance in the e--H scattering. The position Er=0.015 eV and width Gamma r=0.012 eV of the H- 1Po shape resonance calculated in the simple one-channel adiabatic approximation are in good agreement with other theoretical calculations.
Journal of Physics B: Atomic, Molecular and Optical Physics, 1991
The hyperspherical adiabatic (HSA) representation is introduced in barycentric coordinates for he... more The hyperspherical adiabatic (HSA) representation is introduced in barycentric coordinates for helium-like systems in which isotopic and correlation effects are taken into account exactly. Different methods of forming the HSA basis are considered. The general classification of the HSA basis states is suggested, and examples of correlation diagrams are presented. The complete classification of doubly excited states of two-electron systems
Theory of two-photon ionization via intermediate dissociative states is developed. The theory is ... more Theory of two-photon ionization via intermediate dissociative states is developed. The theory is applied to the one-color two-photon ionization of CH3I for which the 3Q0 and 1Q1 dissociative states serve as intermediate resonances. Both CW and transient ionization spectra are calculated. The computed methyl iodide CW ionization line intensities are in profound disagreement with line intensities derived from two-photon zero
Control over the product branching ratio in the photodissociation of Li2 into Li(2s)+Li(2p) and L... more Control over the product branching ratio in the photodissociation of Li2 into Li(2s)+Li(2p) and Li(2s)+Li(3p) channels is explored computationally using the pump-pump coherent control scenario. Extensive control over the Li(3p)/Li(2p) branching ratio is demonstrated as the delay time between the two pulses is varied. The pulse width dependence is examined and better control is found to result from a narrow
We present an application of ‘‘optimal squeezing’’ theory to the design of laser pulses for gener... more We present an application of ‘‘optimal squeezing’’ theory to the design of laser pulses for generation of squeezed states of material waves (states whose localization in some variable exceeds that of the ground state) in Na2. Spatiotemporal evolution of the squeezed states during and after the laser pulse is studied. We show that the optimized laser pulses can affect squeezing
Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2B... more Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2Br+I or CH2I+Br is examined computationally. Quantum photodissociation calculations, using two excited potentials surfaces, are carried out using a new method incorporating negative imaginary absorbing potentials within the artificial channel method. Extensive control over the I/Br branching ratio is shown to result as experimentally controllable laser amplitudes
ABSTRACT A FORTRAN program is presented which solves the Sturm-Liouville problem for a system of ... more ABSTRACT A FORTRAN program is presented which solves the Sturm-Liouville problem for a system of coupled second-order differential equations by the finite difference method of the second order using the iterative Richardson extrapolation of the difference eigensolutions on a sequence of doubly condensed meshes. The same extrapolational procedure and error estimations are applied to the eigenvalues and eigenfunctions. Zero-value (Dirichlet) or zero-gradient (Neumann) boundary conditions are considered. (C) 1998 Elsevier Science B.V.
A method for numerical solution of the coupled-channel Schrödinger equation for bound states base... more A method for numerical solution of the coupled-channel Schrödinger equation for bound states based on the finite-difference method of the second order with iterative extrapolation of net eigensolutions is described. It is shown that Richardson's extrapolation to the limit significantly increases the accuracy of the finite-difference solutions with substantial reduction of requirements in computer memory, disk storage and computational time.
Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2B... more Coherent control over branching in the photodissociation of collinear CH2BrI to yield either CH2Br+I or CH2I+Br is examined computationally. Quantum photodissociation calculations, using two excited potentials surfaces, are carried out using a new method incorporating negative imaginary absorbing potentials within the artificial channel method. Extensive control over the I/Br branching ratio is shown to result as experimentally controllable laser amplitudes
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Papers by Dmitri Abrashkevich