Results Of Specific Calculations Research Articles

Calculation of the coefficient of local hydraulic diaphragm resistance in transitional and laminar areas of flow

In the case of hydraulic machines and devices, local hydraulic resistances, as a rule, constitute the determining part of the total head losses during the operation of any hydraulic machine. The most detailed reference book, which has gone through many editions in our country and published abroad, is the “Reference book on hydraulic resistance” by I.E. Idelchik. At the same time, the analysis carried out in the cited literature showed that, depending on the year of publication of the reference book by I.E. Idelchik, for the same local resistance, the difference in the numerical values of the same local hydraulic resistance can reach a multiplicity. The purpose of this work is to analyze the recommendations given in the handbook for calculating the hydraulic resistance coefficient of diaphragms (holes) with any edge shapes for various conditions of flow overflow in the transition and laminar regions inside a pipeline of constant cross-section. In particular, it is shown that tabular values are recommended for calculating the filling factor of the diaphragm section and an analytical dependence is given, the differences in the numerical values of which reach 15%, which introduces uncertainty in the results of specific calculations. To a much greater extent, a similar situation takes place when using the recommendations for calculating the coefficient of hydraulic resistance. In this case, also, the given numerical tabular values of the coefficients of hydraulic friction resistance when the flow passes through the hole and calculated from the given analytical dependence, differ in multiplicity, which indicates the absence of a connection between them. This issue requires further special consideration.

Theory of electron-wave devices for the short-wave part of the microwave band

The applicability of electron-wave devices in the short-wave part of the microwave band is theoretically studied. The approximate nonlinear theory of double-beam instability and the results of specific calculations are briefly analyzed. A general linear theory of the double-beam orotron, which demonstrates an increase in the interaction power of electron flows, is presented. A new operating mode of the electron-wave tube, which is called the interference mode, is described.

Optical binding and the influence of beam structure

An optically induced interparticle potential, applicable to particles of any shape, is derived in a formulation that accommodates the effects of beam structure. The theory allows the consideration of optical binding interactions in beams of spatially varying irradiance and polarization. Results of specific calculations are exhibited for spherical particles in linearly, circularly, and radially polarized Laguerre-Gaussian beams, leading to the identification of several possible optically induced particle arrangements. The patterning of these optically induced structures is shown to have an identical dependence on the optical wavenumber and spot size at the beam waist.

Luminescence and absorption spectra of polyatomic molecules subjected to conformational transitions

A general approach and results of specific calculations of conjugated vibronic absorption and fluorescence spectra of “soft” molecules subjected to conformational transitions are presented. The vibronic spectra of these molecules exhibit significant anomalies such as a large energy gap between the fluorescence and absorption spectra, a strong deviation from the mirror symmetry, etc., which cannot be explained within the framework of the theory of vibronic spectra based on single-well adiabatic potentials.

Spatial correlations in quasi-crystalline structures

A quasi-crystal is generated from a given, higher-dimensional, parent periodic lattice. Translations of this lattice within a unit cell generate all non-identical states of the same, uniquely defined, physical quasi-crystal. An ensemble-averaging procedure over these states is utilised to obtain the pair distribution and coordination numbers of the quasi-crystal. Results of specific calculations are given for the primitive icosahedral quasi-crystal. A scheme is given for the construction of general decorated quasi-lattices and their corresponding singlet and pair distributions. Implications for icosahedral quasi-crystals and their packing densities are discussed.

Anomalous ground-state configurations in some odd-odd deformed nuclei

The ground-state configuration in certain odd-odd nuclei is found to differ from that expected from the superposition of the ground states in the neighbouring odd-A nuclei. Such anomalies are pointed out for a few nuclei in both the rare-earth and actinide regions for which either the proton or the neutron configurations for the ground state in the odd-odd system correspond to that of the excited state in the respective odd-A system. The origin of this anomaly is attributed to an unusual contribution from the residual n-p interaction term to the band-head energy and the results of specific calculations in a parameter-independent formulation which satisfactorily explain the observed re-ordering of the two-quasiparticle states in the spectra of odd-odd nuclei.

Quantum-chemical calculations of electronic structures and molecular properties within the framework of approximate schemes of zero differential overlap. II. Results of specific calculations of molecular properties within the framework of semiempirical ZDO schemes

The previous part [i] of the present review gave a methodological analysis of the internal justification for the approximation of zero differential overlap and published schemes for selecting the parameters in the semiempirical CNDO, INDO, etc. approaches. In the present work we analyze the results of specific calculations for inorganic compounds, carried out within the framework of semiempirical ZDO approaches, in order to estimate the possibilities provided by these approaches and their accuracy and reliability for various molecular properties in different classes of molecule.

Radial inhomogeneity of excitation of various dyes in a cylindrical cuvette

The question of the radial distribution of pumping in general has been investigated quite fully [i], including the case of dye lasers [2-6]. Although there have been investigations in which the reverse effect of the active medium on the parameters of the emitting plasma [5, 6] has been considered, the traditional approach has been to represent the pump source as a blackbody at an assigned temperature (see [2-4]). Published results of specific calculations relate only to Rhodamine 6G[3-5].

Structure of the boundary layer between a rarefied plasma and a magnetic field

The stationary problem of the structure of the plane boundary layer between a magnetic field and a collisionless plasma is solved. A method is proposed for numerically solving a system of nonlinear equations for a selfconsistent electromagnetic field. This method makes it possible to obtain, for a broad class of plasma particle distribution functions, a complete spatial picture of the boundary layer without the assumption of electrical neutrality. Results of specific calculations for normal and oblique incidence of a plasma on a “magnetic wall” are discussed. The entire study is carried out in relativistic-invariant form.