scholarly journals Some problems of modeling laser-induced filaments

2020 ◽  
Keyword(s):  
Experimental Data ◽  
Silicon Carbide ◽  
Nonlinear Optical ◽  
Cherenkov Radiation ◽  
Optical Breakdown ◽  
Point Of View ◽  
Chain Process ◽  
Chemical Bonds ◽  
Physical Chemical ◽  
Optical Transformation

Experimental data of formation laser-induced filaments in various media (potassium chloride, water, air and silicon carbide) are represented. These phenomena are analyzed as processes of Nonlinear and Relaxed Optics. Problems of modeling the creation the volume laser-induced filaments are investigated. Comparative analysis of plasma, nonlinear optical, diffractive and interference phenomena (including diffractive stratification), shocking processes (including Cherenkov radiation) and physical-chemical processes (including cascade model of excitation the proper chemical bonds in the regime of saturation the excitation), methods and models are represented and discussed. The optical breakdown for various matters has various natures: from shock ionization of gas to disruption of all chemical bonds for solid in the region of interaction light and matter or from nonequilibrium radiated processes in gas and liquid to irreversible phase transformations in solid. For diffraction stratification the modified models of Rayleygh rings was used. We show that this model allow to explain the experimental data for silicon carbide more effectively as Lugovoy-Prokhorov theory of moving foci. Modified Niels and Aage Bohrs models (microscopic) and Golub model (macroscopic) of Cherenkov radiation were used for the explanation of generation continuous radiation. Diffraction stratification shows the surface conic nature of Cherenkov radiation. It was show that physical-chemical method of estimations of corresponding processes is more general as electromagnetic (Kerr media) and one allow explain basic terms of resulting chain process with united point of view. Modified I. Frank model of interference the Cherenkov radiation was used for the explanation laser-induced optical breakdown in silicon carbide. Modified Rayleygh model and methods of continuum mechanics was created and used for the estimation sizes and form of observing nanovoids of silicon carbide. In whole the represented models allow to explain the corresponding chain more fuller and really as other models because one take into account of nonlinear optical transformation of primary laser radiation.

Electron Pairing and Chemical Bonds. Physical Meaning of Effective Pairs

1994 ◽  
Vol 59 (12) ◽  
pp. 2567-2578 ◽  
Author(s):  
Robert Ponec ◽  
Filip Uhlík
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Physical Meaning ◽  
Electron Density Distribution ◽  
Mutual Coupling ◽  
Population Analysis ◽  
Point Of View ◽  
Chemical Bonds ◽  
Conditional Probabilities ◽  
Electron Pairing

The physical meaning of the so-called effective pairs which have been introduced recently within the formalism of pair population analysis is discussed using the analysis of conditional probabilities of electron density distribution for electron 1 with the reference electron fixed in a certain point 2. It is demonstrated that from the point of view of the mutual coupling of electron motions, the effective pairs behave analogously to singlet pairs. Based on this finding, effective pairs can be interpreted as the fraction of singlet pairs that is directly involved in bonding.

The Mechanical Modeling of Oxygen-Containing Precipitates in Silicon Wafers on Different Stages of the Getter Formation Process

2011 ◽  
Vol 178-179 ◽  
pp. 483-488
Author(s):  
Pavel S. Shushpannikov ◽  
Robert V. Goldstein ◽  
Konstantin Ustinov
Keyword(s):  
Experimental Data ◽  
Silicon Wafer ◽  
Formation Process ◽  
Strain State ◽  
Spherical Shape ◽  
Point Of View ◽  
Dislocation Loops ◽  
Mechanical Modeling ◽  
Silicon Matrix ◽  
Spheroidal Inclusion

The behavior of the oxygen-containing precipitate in silicon wafer on different stages of the getter formation process is considered from the mechanical point of view. The precipitate is modeled as a spheroidal inclusion undergoing inelastic eigenstrains in an anisotropic silicon matrix. The stress-strain state in the precipitate and matrix is calculated within the framework of the model. An energetic criterion of breaking the spherical shape by the coherent precipitates is obtained and analyzed. Criteria of the formation and onset of motion of the dislocation loops in the vicinity of the precipitate are also proposed. The obtained results are compared with the available experimental data.

scholarly journals РІВНІ ІНШОМОВНОЇ КОМПЕТЕНТНОСТІ МАЙБУТНІХ ФАХІВЦІВ СОЦІАЛЬНОЇ СФЕРИ

2019 ◽  
pp. 16-20
Author(s):  
Павелків К. М.
Keyword(s):  
Experimental Data ◽  
Foreign Language ◽  
Experimental Research ◽  
Point Of View ◽  
Language Training ◽  
Self Assessment ◽  
Language Competence ◽  
Social Sphere ◽  
Competence Level ◽  
The University

The article presents the results of experimental research of foreign language competence level of future social sphere specialist. The experimental data are compared with the results of students’ under study self-assessment of their foreign language competence level. The article shows the results of the influence of methodological system of foreign language training of future social sphere specialist on the increase of the level of foreign language competence among participants of experimental groups. Creative, medium, satisfactory and unsatisfactory levels of foreign language competence of future social sphere specialist are characterized from the point of view students’ reflexion. The research approves the effectiveness of pedagogical influences introduced at the forming stage of the experiment through approbation of the author’s methodical system of foreign language training in the university.

Constraints to the modelling of diet selection and intake in the grazing ruminant

1996 ◽  
Vol 47 (2) ◽  
pp. 257 ◽  
Author(s):  
H Dove
Keyword(s):  
Decision Support ◽  
Diet Selection ◽  
Point Of View ◽  
Botanical Composition ◽  
Factors Influencing ◽  
Major Constraint ◽  
Physical Chemical ◽  
Herbage Intake ◽  
Spatial Terms ◽  
Future Work

The interaction of grazing animals and their pasture generates substantial income for Australia, so that an interest in modelling the processes involved can be justified readily. Based on a brief review of the factors influencing diet selection, it is suggested that, from the point of view of modelling the process, a major constraint has been the availability of accurate and convenient methods for estimating the botanical composition of the consumed diet. It is also suggested that there is a need in future work to define more adequately the available herbage in botanical, physical, chemical and spatial terms, and to conduct experiments in which factors influencing selection are examined in an unconfounded way. It is further suggested that, while the idea of fixed preference or selection coefficients for particular species is attractive from a modelling standpoint, available evidence does not support the concept. Factors influencing herbage intake are then discussed, particularly in relation to the interaction between the degree of rumen fill and the animal's capacity to use energy. The manner in which this interaction has been used in the modelling of intake is then described briefly and the modeling of diet selection and intake within the decision-support system GrazFeed is presented by way of example. Finally, the constraints associated with model validation are discussed briefly, especially in relation to the need in future work to define more adequately the characteristics of the pasture on offer.

FORMATION OF SILICON CARBIDE COATINGS BY CHEMICAL VAPOR DEPOSITION (review). Part 1

2021 ◽  
pp. 100-111
Author(s):  
D.V. Sidorov ◽  
◽  
A.A. Schavnev ◽  
A.A. Melentev ◽  
◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Point Of View ◽  
Technological Parameters ◽  
Technical Literature ◽  
Pure Silicon ◽  
Carbide Coatings ◽  
Complex Process

The article provides an overview of the scientific and technical literature in the field of the formation of silicon carbide coatings by chemical vapor deposition (CVD). CVD is a complex process, approaches to which vary depending on the tasks being solved. Depending on the technological parameters, the initial reagents, the substrate for deposition, the type and design of the CVD reactors, it is possible to achieve both the deposition of pure silicon carbide and the co-deposition of silicon and/or carbon. In the first part of the article, attention is paid to the study of CVD from the point of view of the mechanisms of chemical reactions, the design of the deposition apparatus, the substrates for deposition.

Software Tool for Assessment of Complexity and Variability in Physiological Signals of Respiration

2011 ◽  
Vol 1 (2) ◽  
pp. 28-53
Author(s):  
Ireneusz Jablonski ◽  
Kamil Subzda ◽  
Janusz Mroczka
Keyword(s):  
Complex System ◽  
Experimental Data ◽  
Time Series ◽  
Data Analysis ◽  
Input Signal ◽  
Software Tool ◽  
Point Of View ◽  
Software Implementation ◽  
Physiological Signals ◽  
Event Time

In this paper, the authors examine software implementation and the initial preprocessing of data and tools during the assessment of the complexity and variability of long physiological time-series. The algorithms presented advance a bigger Matlab library devoted to complex system and data analysis. Commercial software is unavailable for many of these functions and is generally unsuitable for use with multi-gigabyte datasets. Reliable inter-event time extraction from input signal is an important step for the presented considerations. Knowing the distribution of the inter-event time distances, it is possible to calculate exponents due to power-law scaling. From a methodology point of view, simulations and considerations with experimental data supported each stage of the work presented. In this paper, initial calibration of the procedures with accessible data confirmed assessments made during earlier studies, which raise objectivity of measurements planned in the future.

Complex Design Method of Ceramic Blades and Metal Disk Connection

2019 ◽  
Author(s):  
Dmitry Sapronov ◽  
Michael Mezencev ◽  
Telman Karimbaev ◽  
Sergey Reznik ◽  
Pavel Prosuntsov
Keyword(s):  
Experimental Data ◽  
Silicon Carbide ◽  
Design Method ◽  
Thermal Contact ◽  
Ceramic Materials ◽  
Thermal Contact Conductance ◽  
Test Pieces ◽  
Complex Design ◽  
Complex Approach ◽  
Metal Disk

Abstract This paper presents a complex approach to designing ceramic blades dovetail joints. Two ceramic materials were considered: diamond reinforced silicon carbide and hot pressed silicon nitride (only in contact testing). The model blades were made from diamond reinforced silicon carbide due to its availability and mature technology. Part 1 describes the models of mechanical and thermal contact and contains experimental data on contact strength and thermal contact conductance. Part 2 investigates the effect of stress concentration and scale factor on the fracture of ceramic test pieces. Part 3 proposes a theoretical-experimental method to estimate friction coefficient in a dovetail joint. We also investigated the character of the ceramic blades fracture during the rotor spin-up. Part 4 deals with automating the design process of the ceramic blades dovetail joints using experimental data.

scholarly journals Mechanism of reaction of silica and carbon for producing silicon carbide

2019 ◽  
Vol 45 ◽  
pp. 146867831989141
Author(s):  
Bahador Abolpour ◽  
Rahim Shamsoddini
Keyword(s):  
Experimental Data ◽  
Silicon Carbide ◽  
Reaction Kinetics ◽  
Direct Effect ◽  
Solid Reaction ◽  
Carbon Reduction ◽  
Temperature Range ◽  
Carbon Particles ◽  
Mechanism Of Reaction ◽  
Kinetics Of

The reaction kinetics of carbon reduction of silica were investigated using thermodynamic concepts and by fitting to relevant models the experimental data obtained for this reduction using a thermogravimetric unit in the temperature range of 1566 to 1933 K. The results show that the only way to produce SiC in this reduction is the reaction of Si, SiO, or SiO2 at the surface or by diffusion of SiO inside the carbon particles while CO and CO2 have no direct effect on the process. The controlling step of this reduction at temperatures lower than 1750 K is the chemical gas–solid or solid–solid reaction at the surface of the carbon particles, while at higher temperatures, the rate of SiO diffusing inside the carbon particles controls the rate of this reduction.

scholarly journals A Chiral Bis(salicylaldiminato)zinc(II) Complex with Second-Order Nonlinear Optical and Luminescent Properties in Solution

Inorganics ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 25 ◽  
Author(s):  
Paola Matozzo ◽  
Alessia Colombo ◽  
Claudia Dragonetti ◽  
Stefania Righetto ◽  
Dominique Roberto ◽  
...  
Keyword(s):  
Schiff Base ◽  
Nonlinear Optical ◽  
Luminescent Properties ◽  
Second Order ◽  
Point Of View ◽  
Zinc Complexes ◽  
Schiff Base Ligands ◽  
Organic Hybrid ◽  
Optical And Luminescent Properties ◽  
Organic Hybrid Material

Whereas there is an increasing amount of reports on the second-order nonlinear optical (NLO) and luminescence properties of tetradentate [N2O2] Schiff base–zinc complexes, the study of zinc complexes having two bidentate [NO] Schiff-base ligands is relatively unexplored from an NLO point of view. This work puts in evidence that the known chiral bis{2-[(R)-(+)-1-phenylethyliminomethyl]phenolato-N,O}zinc(II) complex is a fascinating multifunctional molecular inorganic–organic hybrid material characterized by interesting second-order NLO and luminescent properties in solution. The emissive properties of the organic 2-(R)-(+)-1-phenylethyliminomethyl]phenol proligand are greatly enhanced upon coordination to the inorganic Zn(II) center.

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