共查询到20条相似文献,搜索用时 31 毫秒
1.
L. V. Kuksa B. I. Koval'chuk A. A. Lebedev V. I. Él'manovich 《Strength of Materials》1976,8(6):678-682
1. | The use of the method developed for determining the main deformations of microvolumes makes it possible to investigate peculiarities of metal deformation in microareas and the actual level of micrononuniform deformation, taking into consideration the form of stressed condition |
2. | A definite character of distribution of the main deformations across microareas, reflecting not only the influence of the form of stressed condition of the macrovolume of a sample, but also the peculiarities of interaction of individual microvolumes which are found in stress deformed conditions differing from the stress deformed condition of the individual body, corresponds to each form of stressed condition. For complex loading a change in the form of distributions of deformations in changing from one form of loading to another is characteristic. |
3. | In the plane stressed condition under conditions of simple and complex loading there is intense slip formation accompanied by activation of a larger number of slip systems than in uniaxial loading, which is an indication of the more complex deformation conditions of individual microvolumes. |
4. | Differences in the distribution of main deformations across microareas, nonuniformity of the stress deformed conditions of microvolumes, and peculiarities of the character of slip formation undoubtedly play a major role in the formation of mechanical properties in the given forms of stressed condition and methods of complex loading. |
2.
S. I. Starchenko 《Measurement Techniques》1998,41(4):375-377
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. 相似文献
3.
Yu. S. Gerasimenko N. A. Belousova M. V. Nechai E. A. Shlokova 《Materials Science》1996,31(3):302-306
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. 相似文献
4.
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. 相似文献
5.
H. Schippers 《Journal of Engineering Mathematics》1982,16(1):59-76
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. 相似文献
6.
O. M. Al'chikova Kh. A. Akhmedzhanov V. G. Ben'kovskii V. G. Gladov 《Journal of Engineering Physics and Thermophysics》1967,12(6):432-435
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
- pat
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 相似文献
7.
P. V. Tsoi 《Journal of Engineering Physics and Thermophysics》2000,73(4):749-761
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. 相似文献
8.
9.
Effects of the morphology of the electrode nanostructures on the performance of dye-sensitized solar cells 总被引:2,自引:0,他引:2
Nicholas N. Bwana 《Nano Research》2008,1(6):483-489
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.
相似文献
10.
N. B. Strokan 《Technical Physics Letters》1998,24(3):186-188
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) 相似文献
11.
1. | On the basis of the experimental investigation of the regularities governing creep of steels 15Kh2MFA and 08Kh18N9 under conditions of a state of plane stress we suggested an equation which makes it possible to determine the minimal creep rate intensity of material in a state of plane stress. As basic data we used the results of creep tests obtained, e.g., under conditions of uniaxial tension and torsion at equal stress intensity levels and at constant test temperature. |
2. | We suggested a criterion of creep of material in the case of a state of plane stress, experimentally substantiated on steels 15Kh2MFA and 08Kh18N9. |
3. | We furnished a quantitative evaluation of the effect of the type of state of stress on the relative minimal creep rate intensity. |
12.
D. C. Ripple R. Davis B. Fellmuth J. Fischer G. Machin T. Quinn P. Steur O. Tamura D. R. White 《International Journal of Thermophysics》2010,31(8-9):1795-1808
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. 相似文献
13.
Two metallic240Pu sources were certified as reference standards of spontaneous-fission activity and neutron flux. The certification results were used to determine the ratio TαTs&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 Ts&f
=(1.16+0.02)·1011 yr for an assumed value Tα=6563+7yr.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 57–58, February, 1995. 相似文献
14.
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. 相似文献
15.
《Materials Research Bulletin》2004,39(4-5):647-654
The almost complete conversion of a powder mixture of the elements into the perovskite-type MgxCyNi3 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 Mg2+xNiCy and Mg1+xNi2Cy, 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 Mg1+xNi2Cy, 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. 相似文献
16.
Freddy Ocanto Ruth Álvarez Beatriz Moy María Brikgi Caribay Urbina de Navarro Carlos F. Linares 《Journal of Materials Science》2008,43(1):190-196
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. 相似文献
17.
Investigation of the harmonic composition of the periodic solution of the Korteweg-de Vries equation
Yu. N. Zaiko 《Technical Physics Letters》1999,25(2):126-127
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) 相似文献
18.
O. P. Ostash L. I. Muravs’kyi T. I. Voronyak A. B. Kmet’ I. M. Andreiko V. V. Vira 《Materials Science》2011,46(6):781-788
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. 相似文献
19.
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. 相似文献
20.
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. 相似文献