Showing papers by "Sofia University published in 1983"
TL;DR: In this paper, the weakly compactly generated (WCG) Banach space admits a Ck-smooth function with bounded support, and partitions of unity of unity.
51 citations
TL;DR: In this paper, a theoretical and experimental study of light-induced autoionizing-like resonance in the continuum at THG of λ=191 nm in sodium vapor is presented, and a gain of the output THG power as much as 18 times due to autoionising-like Resonance has been obtained.
Abstract: A theoretical and experimental study of light-induced autoionizing-like resonance in the continuum at THG of λ=191 nm in sodium vapor is presented. A gain of the output THG power as much as 18 times due to autoionizing-like resonance has been obtained.
32 citations
TL;DR: In this article, a simple two-layer barotropic model is proposed, which consists of a surface (SL) and overlying Ekman-type layer, and the system of dynamic and heat transfer equations is closed using K theory.
Abstract: The temperature and wind profiles in the planetary boundary layer (PBL) are investigated. Assuming stationary and homogeneous conditions, the turbulent state in the PBL is uniquely determined by the external Rossby number and the stratification parameters. In this study, a simple two-layer barotropic model is proposed. It consists of a surface (SL) and overlying Ekman-type layer. The system of dynamic and heat transfer equations is closed usingK theory. In the SL, the turbulent exchange coefficient is consistent with the results of similarity theory while in the Ekman layer, it is constant. Analytical solutions for the wind and temperature profiles in the PBL are obtained. The SL and thermal PBL heights are properly chosen functions of the stratification so that from the solutions for wind and temperature, the PBL resistance laws can be easily deduced. The internal PBL characteristics necessary for the calculation (friction velocity, angle between surface and geostrophic winds and internal stratification parameter) are presented in terms of the external parameters. Favorable agreement with experimental data and model results is demonstrated. The simplicity of the model allows it to be incorporated in large-scale weather prediction models as well as in the solution of various other meteorological problems.
29 citations
TL;DR: In this article, a Green function technique is developed to study the excitations and the damping of the s-d interaction model below Tc, which consists of an acoustic and of an optical spin-wave branch.
Abstract: A Green function technique is developed to study the excitations and the damping of the excitations of the s-d interaction model below Tc. The spectrum of the magnetic excitations is obtained, which consists of an acoustic and of an optical spin-wave branch. The E+ mode is overdamped near Curie point Tc, while it is nearly undamped at low temperatures. The electronic damping is also discussed. Some numerical calculations of various effects are given, using parameters appropriate to the ferromagnetic chalcogenide spinels (such as CdCr2S4).
Mit Hilfe Greenscher Funktionen werden das Anregungsspektrum sowie die Dampfung dieser Anregungen fur das s-d-Modell unterhalb des Curiepunktes Tc berechnet. Das Spektrum der Magnonen wird erhalten, das aus einem akustischen und einem optischen Spinwellenzweig besteht. Die E+-Mode ist in der Nahe von Tc uberdampft, wahrend sie bei tiefen Temperaturen fast ungedampft ist. Die Elektronendampfung wird ebenfalls diskutiert. Numerische Berechnungen werden fur verschiedene Grosen durchgefuhrt, wobei Parameter fur die ferromagnetischen Chalkogenspinelle (wie z. B. CdCr2S4) verwendet werden.
24 citations
TL;DR: In this article, a carbenium ion formation was detected in adsorbed ethene, propene, butene, methanol, and dimethyl ether using the ir and uv spectra.
24 citations
TL;DR: Les ondes de surface d'un plasma electronique non lineaires peuvent avoir une instabilite de modulation and se propager comme des solitons sur une interface vide-plasma electronique froid.
Abstract: Les ondes de surface d'un plasma electronique non lineaires peuvent avoir une instabilite de modulation et se propager comme des solitons sur une interface vide-plasma electronique froid
18 citations
18 citations
TL;DR: The steam distilled oils both from flowers and leaves, as well as from total aerial parts of CHRYSANTHEMUM INDICUM L. (small-flowered form), were obtained and analyzed by GC and GC/MS.
Abstract: The steam distilled oils both from flowers and leaves, as well as from total aerial parts of CHRYSANTHEMUM INDICUM L. (small-flowered form), were obtained and analyzed by GC and GC/MS. Their main components are borneol, chrysanthenone and bornyl acetate.
16 citations
TL;DR: In this article, the authors applied self-deconvolution in Raman spectroscopy and investigated the behavior of the components in the composite Raman spectrum of water (OH-stretching region) versus the concentration of dissolved NaI and NaClO 4 salts.
13 citations
TL;DR: Kupfer(II)-komplexe von Pyrophthalon (PPH) and Iminopyrophalon (IPH) wurden synthetisiert and ihre Struktur mit Hilfe von Molekul-and ESR-Spektroskopie und magnetischer Suszeptibilitat untersucht.
Abstract: Kupfer(II)-komplexe von Pyrophthalon und Iminopyrophthalon
Kupfer(II)-komplexe von Pyrophthalon (PPH) und Iminopyrophthalon (IPH) wurden synthetisiert und ihre Struktur mit Hilfe von Molekul- und ESR-Spektroskopie und magnetischer Suszeptibilitat untersucht. Es wurde festgestellt, das die Komplexe mit einem Metall-Ligand-Verhaltnis von 1:2 und mit einer Struktur eines verzerrten Tetraeders gebildet werden.
Die IR-Daten zeigen das die koordination durch das O-Atom der Enol-From der Liganden und dem N-Atom des Pyridinringes realisiert wird
11 citations
TL;DR: In this article, the performance of an electro-optic light modulator under high average laser power is studied theoretically and experimentally, and the performance degradation of the modulator is analyzed.
Abstract: The performance of an electro-optic light modulator under high average laser power is studied theoretically and experimentally. Absorption of laser radiation produces a thermal gradient in the electro-optic crystal which degrades the performance of the modulator. Measurements on modulators using KDP and KD*P crystals support the analytical results.
TL;DR: In this paper, the interpretation of the critical supersaturation at water condensation on hexadecane, put forward in [3], is now completed with the treatment of the barrier mechanism of a new phase formation in the case of negative line tension (κ<0).
Abstract: The interpretation of the critical supersaturation at water condensation on hexadecane, put forward in [3], is now completed with the treatment of the barrier mechanism of a new phase formation in the case of negative line tension (κ<0). Instead ofκ=−1.50×10−5 dynes, estimated in [3], a value ofκ=−1.16×10−5 dynes is obtained here. However, the analysis of the extrapolation, through which the critical supersaturation is determined in [3], indicates that the sensitivity of detecting the initiation of the process of condensation used there corresponds most probably to the outset of barrierless phase formation. Therefore, the value ofκ=−1.50×10−5 dynes obtained in [3] is accurate.
TL;DR: In this article, the chemical shift values suggest an enolate nature of the derivatives even for the most angularly strained lithiocyclopropane carboxylate t-BuO(LiO)C= CCH 2 C H2.
TL;DR: In this paper, the bulk amorphous alloys Sm4Co3, Gd4Co-3, and Er4Co 3 were investigated and their magnetic peculiarities were determined in the temperature range from 4.2 to 300 K.
Abstract: The bulk amorphous alloys Sm4Co3, Gd4Co3, and Er4Co3 are investigated. Their magnetic peculiarities are determined in the temperature range from 4.2 to 300 K. Paramagnetic Curie temperatures 110, 212, and 22 K are measured for Sm4Co3, Gd4Co3, and Er4Co3, respectively. The magnetic moments and the anisotropy energies are also derived.
[Russian Text Ignored].
TL;DR: In this paper, a theoretical study of the surface photovoltaic effect in the sub-bandgap energy range is carried out for semiconductors with deep bulk impurity levels, where recombination kinetics assume one deep bulk acceptor-like level and one or several surface donor-like levels communicating with the valence band.
TL;DR: Most commonly deconvolution technique application in spectroscopy is associated with the removal of the smearing effect due to the finite resolution of the experimental apparatus1,2 as mentioned in this paper, and this is not the case in our case.
Abstract: Most commonly deconvolution technique application in spectroscopy is associated with the removal of the smearing effect due to the finite resolution of the experimental apparatus1,2.
TL;DR: In this paper, the first experimental measurement of nonlinear optical susceptibilities at a laser-induced resonance in the atomic continuum was reported, where Raman amplification efficiency as well as polarization anisotropy were investigated by scanning the probe frequency near the autoionizing-like resonance.
Abstract: The first experimental measurement of nonlinear optical susceptibilities at a laser-induced resonance in the atomic continuum is reported. Raman amplification efficiency as well as polarization anisotropy are investigated by scanning the probe frequency near the autoionizing-like resonance. Tunable ultraviolet radiations by four-photon processes in sodium vapour near the induced resonances are obtained. Estimations of the real and imaginary parts of the nonlinearities and also of their moduli are presented.
TL;DR: In this paper, a Green function technique is used to study the spin-phonon interactions in the Ising model with a transverse field and the renormalized energy of the coupled mode, the damping of the spin waves, and the phonon damping are evaluated.
Abstract: A Green function technique is used to study the effects of spin–phonon interactions in the Ising model with a transverse field. The renormalized energy of the coupled mode, the damping of the spin waves, and the phonon damping are evaluated. The transverse dynamic structure factor exhibits three peaks due to the coupling of the transverse soft-mode and the acoustic phonon mode. The width of the central peak is proportional to the phonon damping.
Die Methode der Greenschen Funktionen wird angewendet, um die Spin–Phonon-Wechselwirkung im Ising-Modell mit transversalem Feld zu untersuchen. Die renormierte Energie der gekoppelten Mode und die Spinwellen- und Phonondampfung werden berechnet. Der transversale dynamische Strukturfaktor zeigt drei Peaks, verursacht durch die Kopplung der transversalen weichen Mode und der Mode der akustischen Phononen. Die Breite des Zentralpeaks ist proportional der Phonondampfung.
TL;DR: Variation de la bande interdite fondamentale avec la temperature: variation analogue a celle de GeTe as discussed by the authors, a variation analogue of the GeTe bande.
Abstract: Variation de la bande interdite fondamentale avec la temperature: variation analogue a celle de GeTe
TL;DR: In this paper, a numerical model of long-range air-pollutant transport is developed, in which a simple planetary boundary layer (PBL) is incorporated, and the pollution field results from the superposition of discrete "puffs" of pollutants which are emitted periodically in different regions.
Abstract: A numerical model of long-range air-pollutant transport is developed, in which a simple planetary boundary layer (PBL) is incorporated. The pollution field results from the superposition of discrete ‘puffs’ of pollutants which are emitted periodically in different regions. The instantaneous sources in the different cells are approximated by rotational ellipsoids with Gaussian concentration distributions. The puff movement due to the external flow is followed by the displacement of the centroid. The expansion of the puff is modelled by nonisotropic Fickian diffusion. A simple barotropic PBL model is used to study the PBL influence. This model gives the flow velocity and the vertical turbulent exchange coefficient, which depend on the external parameters Ro and S — Rossby number and stratification parameter. The model performance is investigated by special test runs. The dependence of the pollution field on source height, stability conditions and vertical motions is shown.
TL;DR: In this paper, the time distribution of resonantly filtered Mössbauer radiation is investigated experimentally and the results are in very good quantitative agreement with the theory developed by Lynch, Holland and Hammermesh in 1960.
Abstract: 2014 The time distribution of resonantly filtered Mössbauer radiation is investigated experimentally. The results are in very good quantitative agreement with the theory developed by Lynch, Holland and Hammermesh in 1960 [1]. It is concluded that the observed discrepancies in the experiments on time dependence of resonantly scattered radiation [3] are due to some unaccounted reason and not to the theoretical approach. J. Physique 44 (1983) 675-677 JuIN 1983, Classification Physics Abstracts 23.20
TL;DR: A simple, selective and accurate spectrophotometric method has been developed for the determination of the cephalosporin-type antibiotic cephazolin and one of its degradation products-2-mercapto-5-methylthiadiazole.
TL;DR: In this article, the quadratic non-linear susceptibility in the single phonon vibronic spectra of molecular crystals is calculated (one Frenkel exciton + one non-totally symmetric phonon), and the following results are obtained: (a) the exciton-phonon interaction is decisive for the appearance of nonlinear susceptibility resonances in the vibronic region; (b) the two-photon absorption spectrum is almost entirely of a oneparticle spectrum.
Abstract: The quadratic non-linear susceptibility in the single phonon vibronic spectra of molecular crystals is calculated (one Frenkel exciton + one non-totally symmetric phonon). The following results are obtained: (a) the exciton—phonon interaction is decisive for the appearance of non-linear susceptibility resonances in the vibronic region; (b) the two-photon absorption spectrum is almost entirely of a one-particle spectrum. The last result is experimentally confirmed elsewhere.
TL;DR: In this paper, a method for determining NO2 in workplace atmospheres, based on its reaction with bis(diethyldithiocarbamato)copper(II) in toluene, was described.
TL;DR: In this paper, the influence of supersaturation, flow velocity and temperature on the linear crystallization rate of different faces of model crystal systems is reviewed. But the experimental results are discussed in the light of the new theoretical treatments on crystal growth from low temperature solutions.
Abstract: This paper is a review of our experimental research on the influence of the supersaturation, flow velocity and temperature on the linear crystallization rate of different faces of model crystal systems. The obtained experimental results are discussed in the light of the new theoretical treatments on crystal growth from low temperature solutions.
[Russian Text Ignore]
TL;DR: One op-amp amplifier circuit with simple digital control of gain absolute value and/or sign is given in this article, where the design procedures and sensitivities are considered, as well as the sensitivity of the circuit.
Abstract: One op-amp amplifier circuit with simple digital control of gain absolute value and/or sign is given. Design procedures and sensitivities are considered.
TL;DR: In this article, measurements of the photoconductivity spectra were used to determine the positions of deep levels in Fe-doped Inp crystals, and a scheme for the electron transitions in n-Inp:Fe was suggested.
Abstract: Measurements of the photoconductivity spectra are used to determine the positions of deep levels in Fe-doped Inp crystals. The data are compared with previously obtained results. A scheme for the electron transitions in n-Inp:Fe is suggested. The possibility of existence of several complexes with participitance of iron is proposed.
[Russian Text Ignored.]
TL;DR: The Kazanlik and Damask roses ditter qualitatively and quantitatively in the composition of the flower waxes.