Über die an „Schwachen“ Grenzflächen Entstehenden Kopfwellen

Zusammenfassung In der vorliegenden Arbeit werden die Kopfwellen untersucht, die beim Auffallen einer harmonischen Schall-Kugelwelle auf die Ebene Grenzfläche zwischen zwei flüssigen Medien entstehen. Vorausgesetzt wird, daß die Grenzfläche schwach ist, d. h. daß die Geschwindigkeit der Schallwellen im Medium mit der Erregungsquelle nur um weniges kleiner ist als die Geschwindigkeit der Schallwellen im Medium ohne die Quelle.

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,

, . , , . . .

     

The influence of plastic deformation on the magnetostriction constant of nickel

The magnetostriction constant of nickel was measured as a function of plastic deformation up to an elongation of 30%. The values of the magnetostriction constant in deformed samples deviate considerably, a fact which cannot be explained by errors of measurement. The absolute value of the magnetostriction constant decreases with increasing plastic deformation (by around 5%).

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30% . , . ( 5%).

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In conclusion the authors thank J. Kaczér, C. Sc. and B. esták, C. Sc. for carefully reading the paper and for their remarks, J. Míová for help in the measurements and workers of the chemical department of our Institute for careful preparation of the samples.     

Zur Frage des Ansprechens eines offenen Geiger-Zählers auf Oberflächenladungen deformierter organischer Isolatoren

Ohne Zusammenfassung

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-

     

A contribution to direct processes in the Co59(p,n) reaction forE p ∼ 6·5 MeV

Nuclear emulsions were used to study the energy spectrum and forward-backward asymmetry of neutrons from the Co⁵⁹(p,n) reaction forE _p 6·5 MeV. It was found that the decay of the compound nucleus makes a maximum contribution of 50% to the reaction yield. Energies of some excited states of the Ni⁵⁹ nucleus were also determined.

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Co⁵⁹(p,n) E _p 6,5 MeV

- Co⁵⁹(p,n) E _p 6,5 MeV. , 50%. , Ni⁵⁹.

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The authors would like to thank all those who helped in this work, particularly all members of the cyclotron group of the Nuclear Research Institute of the Czechoslovak Academy of Sciences, who so willingly helped with the irradiation, and H. Koutová from the Faculty of Technical and Nuclear Physics, who carefully measured the emulsions. Our thanks are also due to R. Krejová from the Faculty of Technical and Nuclear Physics for developing the emulsions and J. Kopecký from the Nuclear Research Institute for providing the cobalt target.     

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.     

The effect of microsegregation on the generation of dislocations in zinc single crystals

The applicability of Tiller's considerations on the production of dislocations is proved. The density of dislocations appearing during impurity microsegregation increases with increasing rate of growth as a consequence of the corresponding change in the effective distribution coefficient. The real value of C at the microsegregation boundaries is at least twice as great as the average value of the concentration of impurities in the crystal in question.

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. , , . C , .

     

Single crystal diffraction patterns of germanium. Part II

The rocking curves of Ge (111), (220), (333) for CuK ₁ radiation were measured by means of the triple-crystal diffractometer. Perfect silicon single crystals, cut parallel to the (111) plane were used in the monochromator part of the triple-crystal diffractometer. The results prove the suitability of such a monochromator for studying diffraction patterns.

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. II

(rocking curves) (111), (220), (333) CuK ₁ . , (111). .

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In conclusion the authors thank A. Haruý for preparing the germanium single crystals and they are indebted to V. Smutná and A. Irra for the care with which they carried out various tasks.     

Sur la remanence de la magnétisation par déplacement des parois de Bloch et la cinétique de sa desaimantation

Sans résumé

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,

     

The connection between low-gradient form of the positive column in oxygen and moving striations

The method of sliding photomultipliers was used to study the connection between two forms of the positive column in oxygen — the so-called low-gradientT-form and the highgradientH-form — and the presence of moving striations in the positive column. It was shown that in theT-form of a positive column striations are always present which move from the cathode to anode with a velocity of several thousand metres/sec. The highgradient form of theH-positive column, on the other hand, is not striated. The non-single-valuedness of the value of the longitudinal electric field in a discharge in oxygen is thus explained by the presence or absence of phenomena of a time variable character.

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— - H - — . , - , /. , , . , , , .

     

Die durch eine Belastung induzierte amplitudenabhängige innere Reibung bei Fe-Ni Legierungen

Ohne Zusammenfassung

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Fe-Ni ,

     

Le pouvoir résolvant du système „objectif-émulsion“

Sans résumé

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New derivation of Bardeen-Shockley formula for mobility of electrons in homopolar semi-conductors

The Bardeen-Shockley formula for the mobility of an electron or hole in a homopolar semi-conductor is derived in a different way to that in which its authors obtained it. The interaction energy of the electron with the acoustic lattice oscillations is derived in an original way. A new possibility for determining the energy gap is given.

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- , , , . . .

     

The quantum theory of the spontaneous magnetization of ferrimagnetics,anti-ferromagnetics and thin films with arbitrary spin at high temperatures

Using Van Vleck's modification of the Heisenberg theory of ferro-magnetism for substances with arbitrary spin per atom, a generalization of the theory is given for the case of ferrimagnetics, anti-ferromagnetics and thin films with an arbitrary number of sub-lattices and with arbitrary spin per atom. The exchange part of the energy operator is formulated by means of rotated spin operators. The theory contains the quantum-mechanical generalization of non-quantum theories given by Néel and later generalized by Yafet and Kittel. It also contains the theory of thin films proposed recently by the author. The magnetization laws are completely analogous to the relations derived from the theory of molecular fields. The constants of the molecular fields are interpreted by means of exchange integrals. For the special case of spin S=1/2the theory agrees with the results of the work of Vlasov and Imuchametov for ferrimagnetics and anti-ferromagnetics and with the author's for thin films.

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,

, , , . . - , . , . , . . S=1/2 .

     

Die Röntgenolumineszenz von NaCl-Kristallen mit Kobalt

Ohne Zusammenfassung

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NaCl

     

Spectral composition of thermoluminescence of coloured NaCl crystals

The paper gives the experimental results of studying the spectral composition of thermoluminescence in the different maxima in photo-chemically coloured pure NaCl crystals or NaCl-crystals containing Cu in different concentrations.

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NaCl

NaCl .

     

Magnetization coils without iron core for high field intensities

A new theory of rectangular coils without an iron core is described which amends the old one of Fabry and Bitter. It enables us to compute field intensities in coils having very small openings, which the old theory could not do.

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, , , .

     

Influence of manganese and oxygen content on tetragonal deformation of copper ferrite

Pure copper ferrite and solid solutions of 0.9 parts of copper ferrite CuFe₂ and 0.1 part of hausmannite Mn₃ were heated in air or in oxygen at various temperatures and either cooled slowly or quenched. All samples with cubic spinel structure contained less oxygen than required by the ideal spinel formula Me²⁺Me ₂ ³⁺ O ₄ ^2– . The addition of hausmannite promotes the formation and/or stabilization of the cubic structure. The lower the heating temperature, the higher the oxygen deficiency necessary for the preparation of cubic samples.

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CuFe₂O_4– Cu_0,88Mn_0,30Fe_1,82O_4± Cu_0,91Mn_0,31Fe_1,82O_4± . , <0; , , (4±) ( ) . Cu-Mn ( –) ó, . , CuFe₂O_4– . ; .

     

Der Einfluss verschiedener Beimischungen auf die Entstehung der Leinen und Baumstruktur in der Glimmentladung in der Atmosphere Luft-Quecksilberdampf

Ohne Zusammenfassung

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—

     

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), . , , .

     

Über die Natur der Magnetomechanischen Erscheinung im Wechselmagnetfeld

Ohne Zusammenfassung

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