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91.
V. S. Dronov L. R. Botvina V. M. Blinov M. R. Tyutin I. A. Afanas’ev 《Russian Metallurgy (Metally)》2006,(5):458-466
The kinetics of development of fatigue microcracks in a high-strength 08Kh14AN4MD steel is studied when a cantilever specimen with several notches is subjected to rotational bending tests. The specific feature of the tests consists in the fact that, when the specimen is loaded at a constant load, different stress amplitudes are realized in different notches. As a result, after the sample has failed across the section with the maximum stress, a longitudinal polished section of the specimen contains fatigue cracks having nucleated in the mouths of the other notches at lower stress amplitudes. A relation between inflection points in the fatigue curve and the conditions of local and developed yield in a notch has been established. Fatigue fracture mechanisms at a superhigh number of loading cycles are studied, and their relation to the structure near a crack is found. A rapid method for estimating the fatigue limit at a superhigh number of loading cycles is proposed. 相似文献
92.
Artem Sokolov Darrell Whitley Andre’ da Motta Salles Barreto 《Genetic Programming and Evolvable Machines》2007,8(3):221-237
This paper evaluates different forms of rank-based selection that are used with genetic algorithms and genetic programming.
Many types of rank based selection have exactly the same expected value in terms of the sampling rate allocated to each member
of the population. However, the variance associated with that sampling rate can vary depending on how selection is implemented.
We examine two forms of tournament selection and compare these to linear rank-based selection using an explicit formula. Because
selective pressure has a direct impact on population diversity, we also examine the interaction between selective pressure
and different mutation strategies. 相似文献
93.
B. V. Kuteev V. Yu. Sergeev V. A. Belopol’sky V. M. Timokhin R. Burhenn 《Technical Physics Letters》2003,29(4):302-304
Experiments performed on a Wendelstein 7-AS stellarator revealed asymmetry of the cloud of an ablating carbon pellet. The cloud is elongated in the direction of large radius toward stronger fields, that is, opposite to the direction expected due to the toroidal drift. In order to study the effect in more detail, the three-dimensional structure of the cloud was analyzed by computer tomography. The results confirmed asymmetry of the cloud. This asymmetry is related to a drift flow existing in the plasma and directed along large radius toward stronger fields. The drift velocity is numerically estimated at ~300 m/s. 相似文献
94.
O. E. Narivs’kyi 《Materials Science》2007,43(1):124-132
We have studied the micromechanism of corrosion fracture of heat-transfer plates of a heat exchanger. The operation of heat
exchangers under conditions of contamination of the plates with a sediment from water leads to their local corrosion under
the sediment. The conditions of operation of the heat exchangers being equal, heat-transfer plates made of AiSi316Ti steel
worked 2.36 times as long as those of AiSi304L steel. The corrosion fracture of plates under the sediment began from pitting
initiation near nonmetallic inclusions of a certain nature. Afterwards, these pittings built up into corrosion spots by the
mechanism of stress corrosion and hydrogen embrittlement.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 1, pp. 110–116, January–February, 2007. 相似文献
95.
A technology for producing ShA and ShB refractories uses high-melting clays from the Rostov Region and high-alumina technogenic waste. The effect of the chamotte-to-clay ratio, the granulometric composition, and the additive introduction method on the properties of products is investigated.__________Translated from Steklo i Keramika, No. 1, pp. 15 – 16, January, 2005. 相似文献
96.
V. B. Baiburin Yu. P. Volkov E. M. Il’in S. V. Semenov 《Technical Physics Letters》2002,28(12):981-982
The surface of a palladium-barium cathode was studied using scanning probe microscopy techniques. Data from the tunneling spectroscopy showed the pattern of the electron work function distribution over a microscopic region on the emitter surface. This pattern is compared to the distribution of various phases in the palladium-barium alloy employed. 相似文献
97.
E. V. Astrova V. V. Ratnikov R. F. Vitman A. A. Lebedev A. D. Remenyuk Yu. V. Rud’ 《Semiconductors》1997,31(10):1084-1090
The results of an investigation of layers of porous silicon (PS), which was obtained by electrochemical etching of p-Si under different illumination conditions — natural light, incandescent light, and light from a mercury lamp with and without
a filter — are reported. The structure of the layers was studied by double-crystal x-ray diffractometry, the composition was
monitored by means of the IR absorption spectra, and the radiative properties were monitored according to the photoluminescence
(PL) spectra. It was established that electrochemical etching under illumination produces PS with a higher porosity and more
intense PL whose maximum is shifted into the short-wavelength region. These changes are accompanied by a large disordering
of the structure and an increase in the oxygen content in the layer. It is concluded that illumination accelerates the chemical
interaction of PS with the electrolyte due to oxidation. High-porosity porous silicon stored in air exhibits quenching of
PL. Conversely, PL is excited in layers with a lower porosity. Aging of PS is characterized by an increase in the microdeformation
of the layers, a decrease in the crystallite sizes with a partial loss of coherence between the crystallites and the substrate,
and an increase in the fraction of the amorphous phase.
Fiz. Tekh. Poluprovodn. 31, 1261–1268 (October 1997) 相似文献
98.
V. B. Mikhailov A. N. Chernenko A. G. Kas’yanov A. B. Shutikhin L. I. Bryukhanov 《Metallurgist》1997,41(9-11):314-316
The Zlatoust Metallurgical Plant has developed a technology that employs semi-dry pressing to make two-layer (composite) heat-insulating inserts for ingot-mold hot tops. The working layer is made of a mixture of materials based on quartz sand, while the insulating layer is based on foamed vermiculate. The binders are sodium silicate solution and commercial lignosulfonate with a density of 1.12–1.20 g/cm3. 相似文献
99.
Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 137–145, September–October, 1993. 相似文献
100.
Yu. B. Afanas’ev E. V. Mokrushina A. A. Nechitailov V. V. Prokof’ev 《Technical Physics Letters》1997,23(3):181-183
The parameters of Bi12TiO20 crystals grown with bismuth oxide of different degrees of purity were measured by a holographic recording technique in an
external ac electric field and were compared with a crystal specially doped with chromium. Various crystal parameters such
as the diffusion length of the photoexcited carriers and the Debye screening length were determined. It was found that the
absorption spectrum of the material and the holographic recording efficiency were strongly influenced by light chromium doping
and by insufficient purity of the starting mixture.
Pis’ma Zh. Tekh. Fiz. 23, 27–32 (March 12, 1997) 相似文献