Stability of laminated orthotropic plates upon slippage of layers

The article deals with a laminated orthotropic plate. Between the layers there is rigid contact as well as contact with frictionless slippage. On the end faces at the level of the neutral surface of the slipping layers the plate is loaded by tangential loads. The model of loss of stability is based on the hypotheses on displacements of the plate that take transverse shear strain into account. Normal displacements of the plate do not depend on the transverse coordinate. The hypotheses derived by iteration make it possible to satisfy the conditions of interlaminar contact, both rigid and with frictionless slippage, with respect to displacements and stresses, and also the conditions on the outer surfaces of the plate. With the aid of Lagrange's variational principle we obtained differential equations under conditions of the precritical and the postcritical state, and also the corresponding boundary conditions. The equations of the postcritical state are written in terms of displacements. On the basis of the presented equations the problem of the stability of a homogeneous orthotropic rectangular plate with pin support along the periphery is solved. It is shown that the results obtained with the suggested model coincide with the known results. The article also examines a square three-layered orthotropic plate under conditions of frictionless slippage contact between the layers and pin support along the periphery. The central layer is loaded by tangential loads on the end faces at the level of its neutral surface. It is shown that when slippage is taken into account, the critical forces are substantially reduced.Translated from Problemy Prochnosti, No. 8, pp. 35–41, August, 1994.     

Geodynamic effect on the state of high concrete dams

Power Technology and Engineering -     

Effect of glucocorticoids on the pharmacokinetics of kanamycin in rabbits

The effect of hydrocortisone on kanamycin pharmacokinetics in rabbits treated with the drugs administered intramuscularly in two different syringes simultaneously and in one syringe was studied. When the drugs were administered in two different syringes, there were no changes in the antibiotic pharmacokinetics as compared to the control group, while administration of the drugs in one syringe resulted in decreased excretion of the antibiotic with urine and a significant increase of its levels in the blood, liquor and tissues.     

PolarDB: An infrastructure for specialized NoSQL datebases and DBMS

This paper presents a new infrastructure for creating specialized databases and database management systems (DBMSs). Some principles of this infrastructure are formulated based on an analysis of various NoSQL solutions. The main features of the proposed approach are: (a) a flexible system of type definitions that allows one to create data structures based on different paradigms and (b) different forms of supporting structured data and mapping them onto the file system. Experiments are carried out to implement RDF graphs, relational tables, name tables, and object-relational mappings. The proposed approach allows one to solve certain problems of developing new technologies for working with Big Data.     

Influence of High-Energy Milling in Hydrogen on the Structural-Phase State of Alloys Based on the Laves Phases

Materials Science - The influence of high-energy milling in a planetary mill in the atmosphere of hydrogen on the structure and phase composition of alloys based on the Laves phases is analyzed. We...     

Increase in the refractive index of alkali titanium-hafnium silicate glass upon Na+ (glass)-Li+ (melt) ion exchange

An increase in the refractive index upon ion exchange in the Li₂SO₄ + Li₂MoO₄ salt melt has been studied for glasses of composition (mol %)xLi₂O-(25 -x)Na₂O-15TiO₂-6HfO₂-54SiO₂, wherex = 0, 5, 10, 15, 20, and 25. The ordinary transparent single-layer and two-layer diffusion zones are obtained. In the latter zone, the optically opaque near-surface layer gives way to a deeper optically transparent layer with the refractive index gradient. The opaque layer produced by the low-temperature exchange exhibits a unique structure, which is permeable to melt. An increase in the refractive index as large as 0.055 is achieved for the first time without fracture and crystallization of glass.