214 research outputs found
Enhacement in the dymanic response of a viscoelastic fluid flowing through a longitudinally vibrating tube
We analyzed effects of elasticity on the dynamics of fluids in porous media
by studying a flow of a Maxwell fluid in a tube, which oscillates
longitudinally and is subject to oscillatory pressure gradient. The present
study investigates novelties brought about into the classic Biot's theory of
propagation of elastic waves in a fluid-saturated porous solid by inclusion of
non-Newtonian effects that are important, for example, for hydrocarbons. Using
the time Fourier transform and transforming the problem into the frequency
domain, we calculated: (A) the dynamic permeability and (B) the function
that measures the deviation from Poiseuille flow friction as a
function of frequency parameter . This provides a more complete theory
of flow of Maxwell fluid through the longitudinally oscillating cylindrical
tube with the oscillating pressure gradient, which has important practical
applications. This study has clearly shown transition from dissipative to
elastic regime in which sharp enhancements (resonances) of the flow are found
Measurements of light background at large depth in the ocean
The mean intensity of Cerenkov emission from the products of K(40) decay and bioluminescence was measured at depths to 5 km. The intensity of ocean light background is found to depend upon depth and at the 5 km level is equal on averaged to 300 + or - 60 quanta/sq cms into spatial angle of 2 pi sterradian in transparency window. The amplitudes, duration and number of BL flashes were measured at various depths. The intensive flashes due to BL are shown to be observed rather seldom at depths over 4 km
Nanostructured coatings based on amorphous carbon and gold nanoparticles obtained by the pulsed vacuum-arc method
Nanostructured coatings based on diamond-like carbon and gold-doped carbon with a thickness of 100-300 nm were obtained by a pulsed vacuum-arc method on silicon substrates. The structure of the coatingswas studied by high-resolution transmission electron microscopy, the elemental composition was studied by X-ray microanalysi
Features of optical characteristics of atmospheric aerosol in the Middle Urals
The results of studies into the aerosol optical depth (AOD) for the atmosphere in the Middle Urals in the spectrum range of 0.34-1.02 μm for 2004-2010 is presented. The interannual, annual, seasonal, and daily variations in the AOD are analyzed. The major statistical characteristics of the AOD, the parameters of the probability density function of distributions over different wave lengths, and the parameters of Angstrom's formula for the different seasons are calculated. The monitoring stations in the Russian segment of the AERONET network are ranked with respect to the AOD value. A shift from March to May in the spring maximum of the AOD is revealed in comparison with the results of the actinometric observations for the period of 1960-1986. A qualitative assessment is given to the influence of forest and peat fires in the region on the AOD. A classification of the states of aerosol haze in the atmosphere according to the AOD values is proposed. © 2013 Pleiades Publishing, Ltd
Extensive Chaos in the Nikolaevskii Model
We carry out a systematic study of a novel type of chaos at onset ("soft-mode
turbulence") based on numerical integration of the simplest one dimensional
model. The chaos is characterized by a smooth interplay of different spatial
scales, with defect generation being unimportant. The Lyapunov exponents are
calculated for several system sizes for fixed values of the control parameter
. The Lyapunov dimension and the Kolmogorov-Sinai entropy are
calculated and both shown to exhibit extensive and microextensive scaling. The
distribution functional is shown to satisfy Gaussian statistics at small
wavenumbers and small frequency.Comment: 4 pages (including 5 figures) LaTeX file. Submitted to Phys. Rev.
Let
Implementation of 14 bits floating point numbers of calculating units for neural network hardware development
An important aspect of modern automation is machine learning. Specifically, neural networks are used for environment analysis and decision making based on available data. This article covers the most frequently performed operations on floating-point numbers in artificial neural networks. Also, a selection of the optimum value of the bit to 14-bit floating-point numbers for implementation on FPGAs was submitted based on the modern architecture of integrated circuits. The description of the floating-point multiplication (multiplier) algorithm was presented. In addition, features of the addition (adder) and subtraction (subtractor) operations were described in the article. Furthermore, operations for such variety of neural networks as a convolution network - mathematical comparison of a floating point ('less than' and 'greater than or equal') were presented. In conclusion, the comparison with calculating units of Atlera was made
Structural features and physico-mechanical properties of AlN-TiB2-TiSi2 amorphous-like coatings
The coating of the AlN–TiB2–TiSi2 system has been produced by the magnetron sputtering of
a target. At the hightemperature (900 and 1300°C) actions the coating crystallization to form crystallites
of sizes 11–25 nm has been observed. It has been defined that the amorphouslike structure is promising
for the use of these coatings as diffusion barriers both as the independent elements and a contacting layer
in multilayer wearresistant coatings. It has been shown that the use of the resultant composite as an effec
tive protective coating for cutting tools will make it possible to increase the tools wear resistance by more
than 30% at the temperature up to 1300°C in the cutting zone
Structural features and physico-mechanical properties of AlN-TiB2-TiSi2 amorphous-like coatings
The coating of the AlN–TiB2–TiSi2 system has been produced by the magnetron sputtering of
a target. At the hightemperature (900 and 1300°C) actions the coating crystallization to form crystallites
of sizes 11–25 nm has been observed. It has been defined that the amorphouslike structure is promising
for the use of these coatings as diffusion barriers both as the independent elements and a contacting layer
in multilayer wearresistant coatings. It has been shown that the use of the resultant composite as an effec
tive protective coating for cutting tools will make it possible to increase the tools wear resistance by more
than 30% at the temperature up to 1300°C in the cutting zone
One-step heterylation at the upper rim of calix[4]arene with 1,2,4-triazin-5(2H)-ones
A convenient way to modify calix[4]arenes based on the direct C-C coupling reaction of their phenol moiety with 1,2,4-triazines has been advanced, and the ability of modified calixarenes to provide transport of La3+ and Ga3+ cations through organic membranes has been examined. © 2006 American Chemical Society
Influence of residual pressure and ion implantation on the structure, elemental composition, and properties of (TiZrAlYNb)N nitrides
The nitrides of highentropy alloys, (TiZrAlYNb)N, fabricated by cathodic vacuum arc evaporation are studied with electron microscopy, atomic force microscopy, laser scanning microscopy; energydispersive Xray analysis, Xray phase analysis, timeofflight secondaryion mass spectrometry; and hardness measurements. It is found that the deposition parameters influence the structure, surface morphology, element distribution, and mechanical properties. The structural–phase state of the coatings before and after the ion implantation of heavy negative gold ions Au– are compared.
DOI: 10
- …