Zur Temperaturabhängigkeit einiger Kenngrössen der Verfestigungskurven von Zinkeinkristallen

Zusammenfassung Es werden Ergebnisse beschrieben über die Temperaturabhängigkeit: der kritischen Schubspannung ₀, des Verfestigungskoeffizienten _A , im BereichA der Verfestigungskurve; des Verfestigungskoeffizienten _B im BereichB, der Längea _A des BereichsA und der Schubspannung _A am Ende des BereichsA. Die kritische Schubspannung wächst im Temperaturbereich 225–344°K linear mit abnehmender Temperatur. Der Temperaturverlauf des Verfestigungskoeffizienten _A , stimmt überein mit älteren Messungen an h.k.p. Metallen. Ähnlich verhält sich der Verfestigungskoeffizient _B . Die Schubspannung am Ende des BereichsA wird durch thermisch aktivierte Vorgänge beeinflußt. Der BereichA verkürzt sich im Temperaturbereich 0–85°C linear mit zunehmender Temperatur. Temperaturwechselversuche zeigen, daß im BereichB thermisch irreversible Änderungen in der Versetzungsstruktur auftreten.

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: ₀, _A , _B , _{A A} . 226 344°K . _A . _B . . 0–85°C . , .

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Herrn Dr. F. Kroupa und Ing. B. esták bin ich für das Durchlesen des Manuskripts sowie wertvolle Hinweise zu Dank verpflichtet. Mein besonderer Dank für zahlreiche fruchtbare Diskusionen und Anregungen gilt Herrn P. Kratochvíl. Herrn Prof. Dr. A. Seeger danke ich ganz besonders für Kritik des Manuskripts und wertvolle Ratschläge.     

Gentle perturbations

By introducing a specific type of perturbation,A, in the Hamiltonian, we define a class of gently perturbed states, ,A, of a canonical ensemble, . The perturbations are chosen so as to preserve a relationship of the form ,A constant ×. Applications in ergodic theory and phase transitions are described.     

ИССЛЕДОВАНИЕ ЭРОЗИЙ НОГО ДЕЙСТВИЯ ИМПУЛЬ СНЯХ ЭЛЕКТРИЧЕСКИХ РАЗРЯ ДОВ С СЛАБЫМ ТОКОМ

50–100 , 1–2 1–10 . - . - . , , - . -.     

ПРИГОТОВЛЕНИЕ И ХАРА КТЕР ПОВЕРХНОСТИ ПЛАСТИНОК AgBr

AgBr . , .     

Замечание К теории по степенного возникновения подви жных слоев в плазме инертных газов

[1] t _B , t _B . , t _B , . .

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A note on the theory of the successive production of moving striations in the plasma of inert gases

Approximate expressions are derived on the basis of Pekárek's theoretical paper [1] for the period of the maximum t_B of a wave packet produced by the passage of a wave of stratification before the aperture of a photomultiplier, and for its time width in the half-height t_B. The relaxation time of a wave of stratification, following from the theory [1], can thus be calculated by means of the experimentally measured velocity of motion of the maximum of a wave packet u and its width t_B. The calculation is supplemented by numerical data on the magnitude of errors committed by using approximate expressions.

     

The elastic coupling between longitudinal and transversal vibrations оf isotropic rods II. Rods of circular cross-section

The new approximative method for calculating the frequencies of longitudinal vibrations of isotropic homogeneous rods described in part I. is used for rods of circular crosssection. Similarly to the rods of rectangular cross-section there does not exist any dead zone of frequencies.

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II.

, I. (. . 366), . , , .

     

Amplitude and energy coefficients of reflected and refracted light

The tensor of reflected and refracted light was first introduced into the principal axes and then the latter were transformed into thep ands direction of the electric field strength. The amplitude coefficient of thep-components of refracted light has different forms depending on which complex unit vector is unit with respect to the square or the absolute value. The energy coefficient has the same value in both cases.

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, p s . p- , . .

     

Ferromagnetic resonance in thin cobalt films

The paper gives the results of measuring ferromagnetic resonance on thin cobalt films, vacuum deposited on unheated glass slides. The values of the (g-factor, the width of the curve, the effective stress and uniaxial induced anisotropy were determined as a function of the thickness of the film from measurements of the ferromagnetic absorption in a magnetic field normal and parallel to the surface of the film. Measurements were carried out on a frequency of 9200 MHz and on film thicknesses of 180 to 1800 Å. A qualitative explanation of the observed dependences is given.

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, . , , g-, , , . 9200 MHz 180–1800 Å. .

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The author thanks V. Kamberský and Z. Málek, C. Sc., for providing some of the cobalt films and for help in depositing and measuring the thicknesses, S. Kadeková and M. Polcarová for valuable advice in determining the structure of the films, J. Míová for carefully plotting the results of measurements and Z. Málek and O. tirand for carefully reading the paper and for valuable discussions.     

On the photo-electroluminescence of ZnS-Cu

The influence of weak ultra-violet irradiation on the brightness waves of electroluminescence is investigated for two types of ZnS-Cuphosphors. The observed effects (increase in brightness in the primary peak and its phase shift, the disappearance of the secondary peak) are explained on the basis of present-day conceptions on electroluminescence.

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ZnS-Cu

ZnS-Cu. ( , ) .

     

On the mass spectrum of the 2+1 gauge-Higgs lattice quantum field theory

We investigate the mass spectrum of a 2+1 lattice gauge-Higgs quantum field theory with Wilson action A _P+A _H, whereA _P(A _H) is the gauge (gauge-Higgs) interaction. We determine the complete spectrum exactly for all , >0 by an explicit diagonalization of the gauge invariant transfer matrix in the approximation that the interaction terms in the spatial directions are omitted; all gauge invariant eigenfunctions are generated directly. For fixed momentum the energy spectrum is pure point and disjoint simple planar loops and strings are energy eigenfunctions. However, depending on the gauge group and Higgs representations, there are bound state energy eigenfunctions not of this form. The approximate model has a rich particle spectrum with level crossings and we expect that it provides an intuitive picture of the number and location of bound states and resonances in the full model for small , >0. We determine the mass spectrum, obtaining convergent expansions for the first two groups of masses above the vacuum, for small , and confirm our expectations.Research partially supported by CNPq, Brasil     

Systematic perturbation calculation for a non commutative model for a metallic glas

We present a systematic perturbation calculation up to the 4th order in the interaction for a metallic-glas-model with an anisotropic coupling of the conduction electrons to a local two-level-system. The logarithmic-(infrared-)divergent terms for the electronic lifetime are suppressed by exponentially small prefactors in the region I (ET) whereas in the region II (ET) they survive in the general case of non-commuting elastic and inelastic couplings in the Hamiltonian, whereE denotes the level-splittings of the local-system, the excitation energy of the conduction electrons above the Fermi level, andT the thermal energy.     

тЕМпЕРАтУРНАь жАВИс ИМОсть ЁФФЕктА ДЕМБЕ РА НА AgCl

AgCl . –190C +20C. –60C . T–130°C, . .

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The temperature dependence of the Dember effect on AgCl

The condenser method was used to study the temperature dependence of the Dember effect on monocrystalline plates of AgCl when illuminating with ultra-violet light. The dependence was studied from –190C up to room temperature. At approximately –60C a change in the effect from negative to positive was found. At temperatures around –130C there was a maximum the magnitude of which changed when the measurement was repeated. A possible interpretation of the experiments is put forward.

     

МОДЕЛИРОВАНИЕ ЭЛЕКТ РОННО-ОПТИЧЕСКИХ СИС ТЕМ С ОСЕВОЙ СИММЕТРИЕЙ П РИ ПОМОЩИ СЕТИ СОПРОТИВЛЕНИЙ

The paper explains the theory of modelling electrostatic fields by a resistance network. The conditions, which the resistance network must satisfy, are derived and the question of modelling electrodes of different shapes is solved. The finished network and the results obtained on it when modelling a jet for a linear h-f accelerator of electrons are described. Particular attention is paid to the influence of a space charge, the modelling of which is an advantage of this method.

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1- , 1964., , .

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. .     

тРЕхлУЧЕВыЕ ВжАИМОД ЕИстВИь π−-МЕжОНОВ с ИМпУльсОМ 4 GeV/c В пРОпАНОВОИ пУжыРь кОВОИ кАМЕРЕ

Altogether 1648 cases of three-prong interaction of ^–-mesons with a 4 GeV/c impulse were found on 90 000 pictures from a propane bubble chamber 55 × 28 × 14 cm³ in size; all three secondary particles were pions, two having a negative and one a positive charge. Analysis of these cases showed that at an impulse of 4 GeV/c of primary ^–-mesons the process of the coherent production of pions was not observed. On the other hand, this analysis led to an interesting result: (19 ± 9) % of the total number of (⁺, ^–) pairs in A interactions is due to the decay of the meson ^{0 +} + ^–. A value of = (764 ± 36) MeV was obtained for the mass of mesons and = (166 ± 55) MeV fort he width of its resonance curve. Investigation of the distribution of masses in the case in question gave no answer due to the insufficiently determined course of the background curve.

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On leave from:Institute of Physics, Czechosl. Acad. Sci., Lumumbova 1, Praha 8, Czechoslovakia.

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Joint Institute of Nuclear Research, Dubna, USSR.

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Institute of Physics, Czechosl. Acad. Sci., Lumumbova 1, Praha 8, Czechoslovakia.

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Faculty of Mathematics and Physics, Charles University, Brehová 7, Praha 1, Czechoslovakia.

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. , . , . , . . , , . . . .     

Types of von Neumann algebras associated with extremal invariant states

A globalized version of the following is proved. Let be a factor acting on a Hilbert space ,G a group of unitary operators on inducing automorphisms of ,x a vector separating and cyclic for which is up to a scalar multiple the unique vector invariant under the unitaries inG. Then either is of type III or _x is a trace of . The theorem is then applied to study the representations due to invariant factors state of asymptotically abelianC*-algebras, and to show that in quantum field theory certain regions in the Minkowski space give type III factors.     

A contribution to the domain structure of iron whiskers

The paper contains an interpretation of the domain patterns found on iron whiskers. An explanation of the closure structure at the end of a whisker grown in the [111] direction is given on the basis of a quantitative analysis. Structures, which form on whiskers strained by axial pressure and bending, are also dealt with. The results are in good agreement with experiment.

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, . [111]. , . .

     

The influence of the spectral asymmetry of X-ray emission lines on the results of studying defects in crystals by X-rays of different wavelength

Since the asymmetry of X-ray emission lines was found to influence the exact measurements of lattice parameters of powdered samples the author has revised the results she once obtained when carrying out exact measurements of the lattice parameter with radiations of various wavelengths for tungsten crystals containing admixtures of different elements. It is shown that with samples having an inhomogeneous distribution of the admixtures in the crystals the typical graphs of lattice parameter found originally remain when respecting the influence of the spectral asymmetry. On the other hand, with a sintered sample which has been homogeneized by long annealing the introduction of corrections to spectral asymmetry leads to an adjustment of the differences measured originally, for which it was difficult to find a probable explanation.

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, . , , . , , , , , , .

     

К ТЕОРИИ СПОНТАННОЙ Н АМАГНИЧЕННОСТИ ТОНКИХ СЛОЕВ. II. ЧАСТЬ)

- , . - . - - . , . 1956 .     

Study of the Anglular Structure of Emission from the Radio Galaxy 3C295 in the Decameter Wavelength Range

We present the results of observations of the angular structure of the radio source 3C295 at decameter waves using the URAN-1 and URAN-2 interferometers. It is shown that the radio image of 3C295 at these frequencies differs drastically from the structure of this object observed at higher frequencies. The simplest model of the structure of this radio galaxy, comprising one component with a Gaussian brightness distribution of angular size (7.4 ± 0.4)× (8.7± 0.4) at 25 MHz and (9.1± 0.5)× (10.6 ± 0.5) at 20 MHz, is determined. A decrease in the spectral density of the emission with decreasing frequency, observed below 50 MHz, is explained.     

Convective excitation of quasistatic waves in an inhomogeneous anisotropic plasma

Local as well as surface waves excited in a streamingless plasma are investigated. In addition to the gradient instabilities of an isothermal plasma now branches of a convective type are found in plasmas with a hot electron componentZ T _e T _i . Both their frequencies and growth rates may exceed the ion cyclotron frequency, > _Bi even if the effect of the finite ion Larmor radius is negligible. Then the surface waves may become of enhanced importance. We compare, therefore, the conditions for excitation and the growth rates of the surface waves with those of the short wavelength (local) perturbations. Upper estimates of the saturated wave amplitudes are also given. For a special profile of the plasma density the problem is solved analytically also in the plasma boundary layer.On leave of absence from the Physical and Technical Institute, Kharkov, U.S.S.R.