85 research outputs found

    Addition on the Basis of Mix of the Synthesized Hydrosilicates of Calcium and Aluminosilikates for Dry Building Mixtures

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    AbstractThe information about the rheological properties of the dry lime mortar intended for the restoration and decoration of buildings and structures. It is proposed to adjust the properties of the mixture and coatings based on it, the additive, the mineralogical composition of which is represented by synthesized hydrosilicates of calcium and aluminosilicate. The chemical composition of a synthesizable additive is presented. Efficiency of application of the lime composition binder was estimated on change of the rheological properties and kinetics of a set of durability of a composite. The analysis plastogramm testifies that mix on the basis of a lime composition binder is characterized by a faster set of the plastic strength

    Description of harmonic generation in terms of the complex quasienergy. I. General formulation

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    Using the Hellmann-Feynman theorem for quasistationary quasienergy states of a quantum system in an intense laser field, we present the high-order harmonic generation (HHG) amplitude in terms of the complex quasienergy of a bound electron, thereby avoiding the necessity for an explicit form for the electron wave function in HHG calculations. This formulation for the HHG amplitude confirms use of the dual dipole moment (instead of the dipole moment expectation value) in wave-function-based HHG calculations in order to properly account for both the ionization and the Stark shift of the initial bound state in a strong laser field

    Description of harmonic generation in terms of the complex quasienergy. II. Application to time-dependent effective range theory

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    A formulation for the high-order harmonic generation (HHG) amplitude [M. V. Frolov et al., Phys. Rev. A 75, 063407 (2007), preceding paper] is employed to provide analytical results for HHG rates within our recently developed time-dependent effective range (TDER) theory (for time-dependent problems involving weakly bound electron systems). Exact and approximate (including quasiclassical) TDER HHG rates are employed to analyze the accuracy of common approximate methods for HHG calculations. For various specific negative ions with s and p outer electrons, numerical results for HHG spectra are presented over a wide interval of laser frequencies(extending from the tunneling to the multiphoton regimes). The role of initial bound state symmetry effects on the HHG spectra is also analyzed. Finally, Coulomb corrections to TDER results for HHG rates are introduced and discussed

    Comment on “Photodetachment in combined static and dynamic electric fields”`

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    The theoretical analysis of C. Rangan and A. R. P. Rau [Phys. Rev. A 61, 033405 (2000)] on the process of photodetachment of H- in a strong static electric field, which calls into question the predictions of B. Gao and A. F. Starace [Phys. Rev. A 42, 5580 (1990)] and also of M. Q. Bao et al. [Phys. Rev. A 58, 411 (1998)], is shown in this Comment to be incorrect. First, we point out that a number of assumptions of Rangan and Rau’s analysis rest on tenuous theoretical grounds. Second, we adduce two completely independent and different analyses of the problem which precisely confirm the results of Gao and Starace. These independent analyses also provide the interpretation that Gao and Starace’s predicted strong-field effects are due to the exact account of the influence of the static electric field, not only on the final state of the detached electron, but also on the initial bound-electron state

    Static-Electric-Field-Induced Polarization Effects in Harmonic Generation

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    Two static-electric-field-induced effects on harmonic generation are demonstrated analytically and numerically: elliptic dichroism (in which the harmonic yield is different for right and left elliptically polarized laser fields) and elliptical polarization of harmonics produced by linearly polarized driving laser fields. Both effects stem from interference of real and imaginary parts of the nonlinear atomic susceptibilities. Possibilities for experimentally measuring these effects are discussed

    Quantum-mechanical simulations of interaction of many-electron quantum systems with ionizing laser pulses

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    We develop parallel program for numerical simulation of the interaction of intense laser pulses with manyelectron atoms on the basis of the time-dependent Kohn-Sham equations. It is shown that the use of modern computer clusters makes it possible to solve these equations for a wide class of atoms in a relatively small time, determined by the parameters of the laser pulse and electronic configuration of the atom. High accuracy of the numerical code is demonstrated on the example of calculating the high-frequency spectrum of electron current excited during ionization of noble gas atoms by few-cycle laser pulse.Розробляється паралельний програмний код для чисельного моделювання взаємодії інтенсивних лазерних імпульсів з багатоелектронними атомами на основі нестаціонарного методу функціонала щільності. Показується, що використання сучасних багатопроцесорних обчислювальних кластерів дозволяє розв’язати нестаціонарні рівняння Кона-Шема для широкого класу атомів за відносно невеликий час, що визначається параметрами лазерного імпульсу і електронною конфігурацією атома. Демонстрація роботи чисельного коду представлена на прикладі розрахунку спектра високочастотного електронного струму, що збуджується при іонізації атомів інертних газів коротким лазерним імпульсом.Разрабатывается параллельный программный код для численного моделирования взаимодействия интенсивных лазерных импульсов с многоэлектронными атомами на основе нестационарного метода функционала плотности. Показывается, что использование современных многопроцессорных вычислительных кластеров позволяет решить нестационарные уравнения Кона-Шэма для широкого класса атомов за относительно небольшое время, определяемое параметрами лазерного импульса и электронной конфигурацией атома. Демонстрация работы численного кода представлена на примере расчета спектра высокочастотного электронного тока, возбуждаемого при ионизации атомов инертных газов коротким лазерным импульсом

    Gravitomagnetic Effects in the Propagation of Electromagnetic Waves in Variable Gravitational Fields of Arbitrary-Moving and Spinning Bodies

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    Propagation of light in the gravitational field of self-gravitating spinning bodies moving with arbitrary velocities is discussed. The gravitational field is assumed to be "weak" everywhere. Equations of motion of a light ray are solved in the first post-Minkowskian approximation that is linear with respect to the universal gravitational constant GG. We do not restrict ourselves with the approximation of gravitational lens so that the solution of light geodesics is applicable for arbitrary locations of source of light and observer. This formalism is applied for studying corrections to the Shapiro time delay in binary pulsars caused by the rotation of pulsar and its companion. We also derive the correction to the light deflection angle caused by rotation of gravitating bodies in the solar system (Sun, planets) or a gravitational lens. The gravitational shift of frequency due to the combined translational and rotational motions of light-ray-deflecting bodies is analyzed as well. We give a general derivation of the formula describing the relativistic rotation of the plane of polarization of electromagnetic waves (Skrotskii effect). This formula is valid for arbitrary translational and rotational motion of gravitating bodies and greatly extends the results of previous researchers. Finally, we discuss the Skrotskii effect for gravitational waves emitted by localized sources such as a binary system. The theoretical results of this paper can be applied for studying various relativistic effects in microarcsecond space astrometry and developing corresponding algorithms for data processing in space astrometric missions such as FAME, SIM, and GAIA.Comment: 36 pages, 1 figure, submitted to Phys. Rev.

    The Similarity Hypothesis in General Relativity

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    Self-similar models are important in general relativity and other fundamental theories. In this paper we shall discuss the ``similarity hypothesis'', which asserts that under a variety of physical circumstances solutions of these theories will naturally evolve to a self-similar form. We will find there is good evidence for this in the context of both spatially homogenous and inhomogeneous cosmological models, although in some cases the self-similar model is only an intermediate attractor. There are also a wide variety of situations, including critical pheneomena, in which spherically symmetric models tend towards self-similarity. However, this does not happen in all cases and it is it is important to understand the prerequisites for the conjecture.Comment: to be submitted to Gen. Rel. Gra

    All-sky search for long-duration gravitational wave transients with initial LIGO

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    We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

    All-sky search for long-duration gravitational wave transients with initial LIGO

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    We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society
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