scholarly journals Фотоупругие свойства кристаллов сульфата калия

2019 ◽  
Vol 61 (11) ◽  
pp. 2154
Author(s):  
В.И. Стадник ◽  
Р.Б. Матвиив ◽  
П.А. Щепанский ◽  
М.Я. Рудиш ◽  
З.А. Когут
Keyword(s):  
Ultraviolet Radiation ◽  
Short Wavelength ◽  
Elastic Stiffness ◽  
Potassium Sulfate ◽  
Dispersion Dependence ◽  
Transparency Region ◽  
Stiffness Coefficients ◽  
Strontium Borate ◽  
The Matrix ◽  
Order Of Magnitude

The spectral dependences of the absolute piezo-optic coefficients of potassium sulfate crystals are studied and their insignificant dispersion dependence is established. The matrix of elasto-optic coefficients рin of these crystals is filled using the values of elastic stiffness coefficients and absolute piezo-optic coefficients. The coefficient of the acousto-optic efficiency М2 is estimated and it is shown that, considering the highest values, it is more than an order of magnitude higher than that of quartz and strontium borate crystals. Taking into account the short-wavelength boundary of the transparency region of potassium sulfate crystals (~ 170 nm), it is proposed to use them for acousto-optic modulation of ultraviolet radiation.

scholarly journals Photoelastic Properties of Trigonal Crystals

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1095
Author(s):  
Bohdan Mytsyk ◽  
Nataliya Demyanyshyn ◽  
Anatoliy Andrushchak ◽  
Oleh Buryy
Keyword(s):  
Elastic Stiffness ◽  
Interferometric Method ◽  
Absolute Value ◽  
Interferometric Technique ◽  
Stiffness Coefficients ◽  
Half Wave ◽  
Compliance Coefficient ◽  
The Matrix ◽  
The Absolute ◽  
The Right

All possible experimental geometries of the piezo-optic effect in crystals of trigonal symmetry are studied in detail through the interferometric technique, and the corresponding expressions for the calculation of piezo-optic coefficients (POCs) πim and some sums of πim based on experimental data obtained from the samples of direct and X/45°-cuts are given. The reliability of the values of POCs is proven by the convergence of πim obtained from different experimental geometries as well as by the convergence of some sums of POCs. Because both the signs and the absolute values of POCs π14 and π41 are defined by the choice of the right crystal-physics coordinate system, we here use the system whereby the condition S14 > 0 is fulfilled (S14 is an elastic compliance coefficient). The absolute value and the sign of S14 are determined by piezo-optic interferometric method from two experimental geometries. The errors of POCs are calculated as mean square values of the errors of the half-wave stresses and the elastic term. All components of the matrix of elasto-optic coefficients pin are calculated based on POCs and elastic stiffness coefficients. The technique is tested on LiTaO3 crystal. The obtained results are compared with the corresponding data for trigonal LiNbO3 and Ca3TaGa3Si2O14 crystals.

Interply Behavior Exhibited in Compliant Filamentary Composite Laminates

1982 ◽  
Vol 55 (4) ◽  
pp. 1078-1094 ◽  
Author(s):  
J. L. Turner ◽  
J. L. Ford
Keyword(s):  
Shear Strain ◽  
Composite Laminates ◽  
Matrix Material ◽  
Matrix Composites ◽  
Efficient Manner ◽  
Strain Behavior ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Extensional Strain ◽  
Interlaminar Shear

Abstract Cord-rubber composite systems allow a visualization of interply shear strain effects because of the compliant nature of the matrix material. A technique termed the pin test was developed to aid this visualization of interply shear strain. The pin test performed on both flat pads and radial tires shows that interlaminar shear strain behavior in both types of specimens is similar, most of the shear strain being confined to a region approximately 10 interly rubber thicknesses from the edge. The observed shear strain is approximately an order of magnitude greater than the applied extensional strain. A simplified mathematical model, called the Kelsey strip, for describing such behavior for a two-ply (±θ) cord-rubber strip has been formulated and demonstrated to be qualitatively correct. Furthermore, this model is capable of predicting trends in both compliant and rigid matrix composites and allows for simplified idealizations. A finite-element code for dealing with such interply effects in a simple but efficient manner predicts qualitatively correct results.

scholarly journals Thermal processes in molecular gas

1991 ◽  
Vol 147 ◽  
pp. 197-204
Author(s):  
J.P. Chièze ◽  
C. de Boisanger
Keyword(s):  
Ultraviolet Radiation ◽  
Molecular Clouds ◽  
Radiation Flux ◽  
Molecular Gas ◽  
Heating And Cooling ◽  
Collective Motions ◽  
Thermochemical Processes ◽  
Order Of Magnitude ◽  
Short Time ◽  
Non Equilibrium

The dynamics of the cold atomic and molecular gas, on which we focus here, is strongly affected by non equilibrium heating and cooling processes. We give two different examples, in which the breaking of the thermal balance is due respectively to variations of the incident ultraviolet radiation flux, and non equilibrium abundances of H2 molecules in molecular clouds envelopes. Fluctuations of the ultraviolet radiation flux in clumpy molecular cloud envelopes result in the formation or the destruction of dense regions. Large density contrasts, greater than one order of magnitude, are easily achieved in cloud regions of moderate visual extinction. Condensation or expansion develop on quite short time scales, of the order of a few tenth of million year, and induce collective motions which can feed turbulence.Another example of the importance of out of equilibrium thermochemical processes is furnished by the study of the H — H2 transition layers in molecular clouds envelopes. They turn out to be unstable against convection-like motions, driven by the energy released by H2 photodestruction. The gas velocities involved in these motions are, again, typical of the observed turbulent velocity in clouds envelopes.

The Influence of Drying and Stress on the Permeability of Texas Lignite

1977 ◽  
Vol 99 (4) ◽  
pp. 634-640
Author(s):  
T. W. Thompson ◽  
S. Sen ◽  
K. E. Gray ◽  
T. F. Edgar
Keyword(s):  
Applied Stress ◽  
Significant Influence ◽  
Confining Pressure ◽  
Fracture Permeability ◽  
Gasification Process ◽  
Matrix Permeability ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Permeability Increase

Tests have been carried out to quantify the variation in permeability of Texas lignite with drying and with applied stress. It has been shown that the matrix permeability of lignite may be increased from effectively zero to the order of 10 darcies by removing about 20 percent by weight of water. In addition, an increase of confining pressure after drying will reduce the permeability, but only by about one order of magnitude. Drying of the matrix thus may produce matrix permeabilities of the same order as the undried field fracture permeability. The permeability increase of the matrix is initially greater parallel to the bedding than perpendicular, but after further drying the two orientations show similar final permeabilities. This drying effect could have a significant influence on the operation of an in-situ gasification process by increasing the transmissivity and injectivity of the producing seam. Drying of the seam could occur by the flow of unsaturated gas and will be enhanced by combustion.

scholarly journals Effects of tetrahydrofolate polyglutamates on the kinetic parameters of serine hydroxymethyltransferase and glycine decarboxylase from pea leaf mitochondria

1993 ◽  
Vol 292 (2) ◽  
pp. 425-430 ◽  
Author(s):  
V Besson ◽  
F Rebeille ◽  
M Neuburger ◽  
R Douce ◽  
E A Cossins
Keyword(s):  
Kinetic Parameters ◽  
Serine Hydroxymethyltransferase ◽  
Affinity Constant ◽  
Plant Tissues ◽  
Glycine Decarboxylase ◽  
Glycine Cleavage System ◽  
Matrix Space ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Glycine Cleavage

Plant tissues contain highly conjugated forms of folate. Despite this, the ability of plant folate-dependent enzymes to utilize tetrahydrofolate polyglutamates has not been examined in detail. In leaf mitochondria, the glycine-cleavage system and serine hydroxymethyltransferase, present in large amounts in the matrix space and involved in the photorespiratory cycle, necessitate the presence of tetrahydrofolate as a cofactor. The aim of the present work was to determine whether glutamate chain length (one to six glutamate residues) influenced the affinity constant for tetrahydrofolate and the maximal velocities displayed by these two enzymes. The results show that the affinity constant decreased by at least one order of magnitude when the tetrahydrofolate substrate contained three or more glutamate residues. In contrast, maximal velocities were not altered in the presence of these substrates. These results are consistent with analyses of mitochondrial folates which revealed a pool of polyglutamates dominated by tetra and pentaglutamates. The equilibrium constant of the serine hydroxymethyltransferase suggests that, during photorespiration, the reaction must be permanently pushed toward the formation of serine (the unfavourable direction) to allow the recycling of tetrahydrofolate necessary for the operation of the glycine decarboxylase T-protein.

Microstructure Design for a Rotating Disk: With Application to Turbine Engines

2005 ◽  
Author(s):  
Stephen D. Sintay ◽  
Brent L. Adams
Keyword(s):  
Design Space ◽  
Elastic Anisotropy ◽  
Material Design ◽  
Rotating Disk ◽  
Material Model ◽  
Elastic Stiffness ◽  
Fiber Texture ◽  
Material Parameters ◽  
Extension Force ◽  
Order Of Magnitude

Through the use of generalized spherical harmonic basis functions a spectral representation is used to model the microstructure of cubic materials. This model is then linked to the macroscopic elastic properties of materials with Cubic Triclinic and Cubic Axial-symmetric symmetry. The influence that elastic anisotropy has on the fatigue response of the material is then quantified. This is accomplished through using the effective elastic stiffness tensor in the computation of the crack extension force, G. The resulting material model and macroscopic property calculations are the foundation for a software package which provides an interface to the microstructure. The Microstructure Sensitive Design interface (MDSi) enables interaction with the material design process and provides tools needed to incorporate material parameters with traditional design, optimization, and analysis software. The microstructure of the material can then be optimized concurrently other engineering models to increase the overall design space. The influence of microstructure on the performance of a spinning disc is explored. The additional design space afforded by inclusion of the material parameters show that for both Cubic Triclinic and Cubic Axial-symmetric material symmetry conditions G can be reduced by more than an order of magnitude. For the Cubic Axial-symmetric condition a Cube <001> fiber texture and a <111> fiber texture are identified as the best performing orientation distributions.

Complete Bandgap in Three-Dimensional Holey Phononic Crystals With Resonators

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Yan-Feng Wang ◽  
Yue-Sheng Wang
Keyword(s):  
Three Dimensional ◽  
Phononic Crystals ◽  
Vibration Modes ◽  
The Finite Element Method ◽  
Local Resonance ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Complete Bandgap ◽  
Careful Design ◽  
Shape And Size

In this paper, the bandgap properties of three-dimensional holey phononic crystals with resonators are investigated by using the finite element method. The resonators are periodically arranged cubic lumps in the cubic holes connected to the matrix by narrow connectors. The influence of the geometry parameters of the resonators on the bandgap is discussed. In contrast to a system with cubic or spherical holes, which has no bandgaps, systems with resonators can exhibit complete bandgaps. The bandgaps are significantly dependent upon the geometry of the resonators. By the careful design of the shape and size of the resonator, a bandgap that is lower by an order of magnitude than the Bragg bandgap can be obtained. The vibration modes at the band edges of the lowest bandgaps are analyzed in order to understand the mechanism of the bandgap generation. It is found that the emergence of the bandgap is due to the local resonance of the resonators. Spring-mass models or spring-pendulum models are developed in order to evaluate the frequencies of the bandgap edges. The study in this paper is relevant to the optimal design of the bandgaps in light porous materials.

Dynamic moduli of rabbit lung tissue and pigeon ligamentum propatagiale undergoing uniaxial cyclic loading

1994 ◽  
Vol 76 (2) ◽  
pp. 773-782 ◽  
Author(s):  
S. M. Mijailovich ◽  
D. Stamenovic ◽  
R. Brown ◽  
D. E. Leith ◽  
J. J. Fredberg
Keyword(s):  
Lung Parenchyma ◽  
Frequency Range ◽  
Connective Tissues ◽  
Dynamic Moduli ◽  
Rabbit Lung ◽  
Mechanical Responses ◽  
Collagenous Tissue ◽  
Lung Parenchymal Strip ◽  
The Matrix ◽  
Order Of Magnitude

In fibrous connective tissue networks, mechanical loads may be transferred from one fiber to the next by friction between slipping fibers (J. Appl. Physiol. 74: 665–681, 1993). Here we tested that hypothesis; it predicts that elastance of fibrous networks increases with increasing frequency, decreases with increasing strain amplitude (delta epsilon), and decreases with tissue swelling by solvent. Similarly, it predicts that hysteresivity (eta) decreases with increasing frequency, increases with increasing delta epsilon, decreases with tissue swelling, and, importantly, exceeds that of isolated fibrous constituents of the matrix. Elastance and eta of two structurally dissimilar connective tissues were measured, the rabbit lung parenchymal strip (a loose collagenous tissue) and the pigeon ligamentum propatagiale (an elastin-rich tissue). Experiments covered the frequency range 0.03125-3.125 Hz. Elastance of lung parenchyma was substantially lower than that of propatagial ligament, increased linearly with the logarithm of frequency, and decreased with delta epsilon; that of ligamentum propatagiale was insensitive to both frequency and delta epsilon. eta of lung parenchyma decreased moderately with increasing frequency and assumed values of approximately 0.1, but eta of ligamentum propatagiale was frequency and delta epsilon invariant and assumed values an order of magnitude smaller. These tissues also showed disparate mechanical responses when exposed to hypertonic bath solutions. Although there were some quantitative differences between predictions and experimental observations, the dynamic behavior of lung parenchyma was generally consistent with that of a network in which load is transferred from one fiber to the next by the agency of friction acting at slipping interface surfaces.

The influence of short wavelength ultraviolet radiation on the healing of thermal wounds (an experimental study)

2016 ◽  
Vol 93 (5) ◽  
pp. 38
Author(s):  
М. М. Rasulov ◽  
I. G. Motorina ◽  
G. G. Yushkov ◽  
V. V. Igumen’shcheva ◽  
N. A. Malyshkina ◽  
...  
Keyword(s):  
Experimental Study ◽  
Ultraviolet Radiation ◽  
Short Wavelength
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