Analysis of the effect of the shape of the radiation pattern on the accuracy of azimuth measurements by the monopulse method

The effect of the shape of the radiation pattern of the difference channel of a monopulse antenna on the accuracy of angular-coordinate measurements is estimated. The least root mean square deviation is obtained using a radiation pattern with a Chebyshev amplitude distribution. Of the practical amplitude distributions a “parabola on a pedestal” of 0.1–0.316 is preferable. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 53–54, April, 1998.     

Estimation of the accuracy of measurements of the corrosion rate by the method of polarization resistance

The method of polarization resistance is extensively used for the determination of the rate of corrosion. At the same time, the accuracy of measurements of the corrosion rate performed with industrial corrosion meters is often not estimated. By using an indicator, we find the accuracy of the measurements of the corrosion rate for 20 steel placed in 1N H₂SO₄ and 0.01N Na₂SO₄ solutions and for 12Kh18N10T steel placed in 1N and 10N H₂SO₄ solutions.Kiev Polytechnic Institute, Kiev. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 3. pp. 22–27, May–June, 1995.     

Influence of the form of the phonon spectrum on the transition temperature of superconductors

The influence of the form of the phonon spectrum on the superconducting transition temperatureT _S under the usual pairing mechanism is investigated. The coupling constant , which determinesT _S in the two-phonon-peak and acoustic dispersion models, is calculated, and its dependence on the usual coupling constant and other parameters is determined. It is shown that the maximum possible value of is unity. An expression is derived forT _S ,making it possible to find the exact numerical value of the coefficient of the exponential function for any form of phonon spectrum.     

On the regularity of the principal value of the double-layer potential

Summary In the present paper we discuss the regularity of the principal value of the potential due to a doublet distribution along the boundary S of a two-dimensional (2-D) open connected set. Assuming S to be a Lyapunov boundary and to be essentially bounded, we prove that the principal value in 2-D is more regular than the one in 3-D. This result is applied to the aerodynamics problem of calculation of potential flows around 2-D bodies.     

On the dispersion of gases under the action of the medium

Some general regularities of dispersion of a gas emerging from a nozzle submerged in a liquid are considered. A condition for establishment of the so-called maximum dispersion state is formulated.Notation ₀ coefficient of surface tension at the liquidgas boundary - contact angle of wetting of the nozzle material surface by the liquid - p_at atmospheric pressure - p air pressure - density of the liquid - g gravitational acceleration - h height of the liquid column - ₁, and _g dynamic viscosity coefficients of the liquid and gas, respectively - R and r radii of the bubble and nozzle, respectively - Q and F dimensionless criteria - , , , , and undetermined coefficients - ratio of the circumference of a circle to its diameter     

Variety of the representation of the nonstationary temperature of fuel elements depending on the form of the distribution of the heat sources

The author proposes a representation of the solution of the heat-conduction equation in the form of expansions in basis functions that are selected depending on the form of the distribution of the internal heat sources. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 761–772, July–August, 2000.     

Effects of the morphology of the electrode nanostructures on the performance of dye-sensitized solar cells

This article reports the performances of dye-sensitized solar cells based on different working electrode structures, namely (1) highly ordered arrays of TiO₂ nanorods, (2) highly ordered arrays of TiO₂ nanotubules of different wall thicknesses, and (3) sintered TiO₂ nanoparticles. Even though highest short-circuit current density was achieved with systems based on TiO₂ nanotubules, the most efficient cells were those based on ordered arrays of TiO₂ nanorods. This is probably due to the higher open-circuit photovoltage values attained with TiO₂ nanorods compared with TiO₂ nanotubules. The nanorods are thicker than the nanotubules and therefore the injected electrons, stored in the trap states of the inner TiO₂ particles, are shielded from recombination with holes in the redox electrolyte at open-circuit. The high short-circuit photocurrent densities seen in the ordered TiO₂ systems can be explained by the fact that, in contrast to the sintered nanoparticles, the parallel and vertical orientation of the ordered nanostructures provide well defined electron percolation paths and thus significantly reduce the diffusion distance and time constant.      

Determination of the uniformity of the carrier lifetime in a material from the profile of the amplitude spectrum of an ion detector

An analysis is made of charge transport in the neutral base of a p ⁺-n structure as a result of its diffusion to the boundary of the p-n junction under conditions where nonequilibrium carriers are generated by single α-particles. It is assumed that nonuniformity of the carrier lifetime (τ), described by a Gaussian distribution, exists over the area of the structure. The profile of the transported charge spectrum is calculated for these conditions and its correlation with the measure of nonuniformity τ is obtained. Since the tracks of the diffusing α-particles occupy an extremely small volume, recording them is equivalent to local probing of the material for τ. It is suggested that the calculated function should be used as a calibration function to determine the spread of τ values in materials. The method is tested on Si for a surface-barrier structure by recording 8.78 MeV π-particles. Pis’ma Zh. Tekh. Fiz. 24, 44–50 (March 12, 1998)     

Determination of the half-life of the spontaneous fission of240PU

Two metallic²⁴⁰Pu sources were certified as reference standards of spontaneous-fission activity and neutron flux. The certification results were used to determine the ratio T_αT_s&f of the alpha-decay and spontaneousfission half-lives of²⁴⁰Pu. The ratio was found to be (5.68+-0.11)·10^−8, which corresponds to T_s&f =(1.16+0.02)·1011 yr for an assumed value T_α=6563+7yr.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 57–58, February, 1995.     

The Roles of the Mise en Pratique for the Definition of the Kelvin

The mise en pratique (“practical realization”) for the definition of the kelvin (MeP-K) was created by the Consultative Committee for Thermometry (CCT) in 2006 to give practitioners of thermometry a guide to the realization of the kelvin, i.e., measurement of temperature in kelvins, in accord with the International System of Units. In this article, the present and the future content of the MeP-K, the relationship of the MeP-K to other documents relevant to thermometry, the categorization of thermometry techniques in the MeP-K, and the benefits of proposed additions to the 2006 version of the MeP-K are discussed. The three categories of measurements within the MeP-K are: (1) primary methods for measuring thermodynamic temperature T; (2) formal approximations to T, in particular, the International Temperature Scale of 1990 (ITS-90) and the Provisional Low Temperature Scale from 0.9 mK to 1 K (PLTS-2000); and (3) indirect approximation methods that are neither primary nor defined on a temperature scale, yet capable of exceptionally low uncertainties or increased reliability. By providing a framework for primary methods and indirect methods, the MeP-K will foster development and application of new methods, such as the use of absolute radiometry or high-temperature fixed points. The MeP-K provides the CCT with a mechanism to update and to expand the thermometric methods in common use, without imposing on industry the high costs of changing the International Temperature Scale.     

Influence of the state of the lattice on the pair breaking of manganese in superconducting cadmium

The superconducting transition temperature of crystalline and amorphous cadmium doped with dilute Mn atoms was measured. In the first case the initial depression ofT _c as function of concentration isdT _c /dc=5.4 K/at % and in the second casedT _c /dc=2.65 K/at %. Both systems show non linear behavior at higher concentrations, the one in the crystalline state much more than the one in the amorphous state. While the curve in the amorphous state fits the Abrikosov-Gor'kov theory to the experimental limit of 70 mK, i.e., to within 3% of the critical concentration, the curve in the crystalline state does not, but is interpretable with the Müller-Hartmann-Zittartz theory with a Kondo temperature of10 ^–6 K.Supported by the Deutsche Forschungsgemeinschaft in the Sonderforschungsbereich 125, Fehlordnung in Metallen Aachen, Jülich, Köln.     

Study of the influence of the basicity and chromate-chloride anionic composition in the synthesis of the cancrinite–sodalite system

The influence of basicity and anionic composition (CrO₄²⁻ and Cl⁻) was studied in the synthesis of chromate-cancrinite and chlorosodalite zeolites. Zeolite X was used as starting material by using different NaOH concentrations (3, 8 and 16 M) and variable weight ratio (NaCl/(NaCl + K₂CrO₄)) equal to: 0.00, 0.25, 0.50, 0.75, and 1.00 in such a way that the total grams were 1.5 g. The syntheses were carried out at 80 °C and autogenous pressure during 40 h. The crystals obtained were characterized by powder X-ray diffraction (XRD), FT-IR spectroscopy, and scanning electron microscopy (SEM) coupled with an energy-disperse X-ray detector (EDX). Depending on the basicity employed and anionic composition (CrO₄²⁻ and Cl⁻), the chromate-cancrinite or chlorosodalite zeolite was obtained. Owing to a low 3 M NaOH concentration and 100% Cl⁻, chlorosodalite mixed with zeolite X was observed in the XRD pattern. Owing to another Cl⁻–CrO₄²⁻ proportions, inclusive to 100% CrO₄², the starting material were not transformed (3 M NaOH). Pure chromate-cancrinite was produced when 8 and 16 M NaOH and 0% Cl⁻ concentrations were used. Chloride anions showed a strong structure directing effect for sodalite framework structure in comparison with chromate anions which favoring the cancrinite structure. Therefore, we determined pure chlorosodalite, when it was used until 75%Cl⁻ (8 M NaOH) and 25% (16 M NaOH). Results showed that cancrinite or sodalite zeolites are separately formed.     

Application of the SHS technique in the synthesis of the perovskite-type MgxCyNi3 compound

The almost complete conversion of a powder mixture of the elements into the perovskite-type Mg_xC_yNi₃ compound has been obtained in two steps, applying the SHS technique followed by an isothermal treatment at 1123 K. No evidence was found for Mg loss due to volatilisation, as well as of unreacted C, at the end of the preparation. Two new ternary phases, that may be referred to as Mg_2+xNiC_y and Mg_1+xNi₂C_y, grew during the combustion process; though different, their crystal structures appear to be strongly related to those of Mg₂Ni and MgNi₂, respectively. Isothermal treatments at 973 K failed in the formation of the perovskite-type compound as a single product, since it was found coexisting with Ni and Mg_1+xNi₂C_y, probably on account of the relatively short reaction times.The samples were characterised by means of XRPD and SEM-EDS analyses after each step of preparation.     

Investigation of the harmonic composition of the periodic solution of the Korteweg-de Vries equation

An investigation is made of the behavior of the nth harmonic of the periodic solution of the Korteweg-de Vries equation as a function of the index n in the intermediate region which is not usually investigated by soliton theory. The asymptotic forms obtained allow the harmonic behavior to be determined more accurately. Pis’ma Zh. Tekh. Fiz. 25, 6–10 (February 26, 1999)     

Determination of the size of the fatigue prefracture zone by the method of phase-shifting interferometry

We consider a new method for determining the size of the fatigue prefracture zone (a new structural-mechanical parameter d* of constructional materials) by the method of phase-shifting interferometry, based on the results of a comparative analysis of the surface profile of metallic specimens in the neighborhood of a constructional stress concentrator prior to and after a certain quantity of loading cycles. To obtain interferograms in laser light, we applied a Twyman–Green interferometer. Using these results, we determined the 3-D distribution of plastic strains near the concentrator vertex, which enabled us to establish that d* = 256–268 μm for low-carbon 08kp steel at a load ratio R = 0.1. The obtained value of this parameter is in good agreement with data obtained by other methods.     

Analysis of the Elastoplastic Deformation of the Material in the Process Zone

By the method of digital correlation of speckle images, we record the displacements in the vicinity of the crack tip in plane specimens of D16AT alloy. The field of elastoplastic displacements is determined in the vicinity of the crack tip under static loading. By using the distribution of displacements, we compute the levels of strains ε _y on the continuation of the crack. The theoretical results are in good agreement with the experimental data in estimating the length of the plastic zone for the limiting equilibrium state.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 5, pp. 67–72, September–October, 2004.     

The effect of natural variations in the isotopic composition on the reproducibility of the temperature of the triple point of water

The effect of long-term natural variations in the isotopic composition on the temperature of the reproduction of the triple point of water – the main reference point of the ITS-90 International Temperature Scale – is investigated. Translated from Izmeritel’naya Tekhnika, No. 12, pp. 31–33, December, 2008.