Cyclic deformation of aluminium and its alloys

The formation of slip bands is the main mechanism of cyclic deformation in pure Al. Their density, orientation and heights in polycrystalline Al were investigated during cycling. Types, sizes and densities of precipitates are responsible for the mode of cyclic deformation in AlCu4 pure alloy. In technical Al alloys intermetallic phases have detrimental effects on deformation homogeneity and largely govern the fatigue mechanism of the material and especially microcrack initiation.     

含氧光敏引发体系的研究——Ⅵ.二苯酮/三乙胺体系引发光聚合过程中的再次引发效应

过去,作者曾发表了多种光敏引发体系引发烯类单体光聚合的工作,在研究2,2-二甲氧基苯乙酮在氧存在下引发甲基丙烯酸甲酯光聚合时,结合在聚合物链端的引发剂碎片具有光化学活性,在光聚合反应中产生高分子自由基,发生再次聚合,出现高分子量     

On Gagliardo–Nirenberg Type Inequalities

We present a Gagliardo–Nirenberg inequality which bounds Lorentz norms of a function by Sobolev norms and homogeneous Besov quasinorms with negative smoothness. We prove also other versions involving Besov or Triebel–Lizorkin quasinorms. These inequalities can be considered as refinements of Sobolev type embeddings. They can also be applied to obtain Gagliardo–Nirenberg inequalities in some limiting cases. Our methods are based on estimates of rearrangements in terms of heat kernels. These methods enable us to cover also the case of Sobolev norms with \(p=1\) .     

Transition to turbulence on the initial section of a circular pipe

All the available data indicate that transition to turbulence in a circular pipe takes place within the initial section. This is confirmed by the conclusions of the linear theory of hydrodynamic stability, according to which the velocity profiles on the initial section of the pipe are unstable [1]. So far, however, there have been few investigations of initial-section flow at different values of the initial perturbation level ₀ at the pipe inlet and different values of the length to diameter ratio of the pipe 2/d. We have now investigated the transition to turbulence in the boundary layer on the initial section of a circular pipe for various ratios of the thickness of the layer to the radius of the pipe and various levels of initial turbulence. The transition point in the boundary layer was found experimentally, since at present there are no reliable methods of calculating it. In particular, the susceptibility problem has not been solved, i.e., the problem of the initial amplitude of the Tollmien—Schlichting wave, the development of which results in transition to turbulence. It may be assumed that the initial amplitude of this wave is determined by the interaction of higher-frequency waves on the section preceding its growth zone [2]. Moreover, different views are held concerning the mechanism of transition to turbulence at ₀ > 0.5%. At the same time, the results of the transition calculations for ₀ > 0.5% based on the three-parameter turbulence model [3] require experimental verification.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 52–56, July–August, 1985.     

Unit checking output tests under constant faults for functional elements

Circuits over bases of functional elements having not more than two entries are considered. The possibility to implement any Boolean function of n variables by a circuit admitting unit checking tests of linear length with respect to n under constant faults is established.     

Gamma-ray bursts from evaporating primordial black holes

It is believed that the detection of gamma-ray bursts from evaporating primordial black holes is highly improbable in the near future since the expected photon flux, consisting mainly of photons with energies ≳ GeV, is too low. Contrary to this point of view, we show that a large fraction of the black hole power at the final stage of evaporation (the last 10³ s) can be liberated as a burst of soft γ-ray emission of duration 10⁻¹–10³ s and luminosity 10²⁸–10³¹ erg/s in the energy range 0.1–1 MeV. According to our calculations of the black hole evaporation rate (within the Standard Model of elementary particles), when the black hole temperature exceeds approximately 10 GeV, the charged particle outflow from a black hole forms a well-defined plasma and can be described in the hydrodynamic approximation. In this case more than half of the rest energy of a black hole can be converted into soft gamma-rays due to the presence of the magnetic field with energy density comparable to that of charged particles. We consider various mechanisms leading to such transformation and estimate their efficiency. It is shown that, at least, some of the gamma-ray bursts detected by BATSE can be associated with evaporating black holes. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 1, pp. 36–45, January, 1998.     

Mikrochemie

Ohne Zusammenfassung     

The effect of LH wave on the peripheral plasma of TM-1-MH tokamak

The work is devoted to the study of the LH wave effect on the peripheral plasma of the TM-1-MH tokamak. The observed enhancement of the ion saturated current in the limiter shadow is interpreted as heating of the peripheral ions by absorption of decay waves generated in this region due to the nonlinear wave-plasma interaction.