共查询到20条相似文献,搜索用时 133 毫秒
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L. Aubrecht 《Czechoslovak Journal of Physics》1973,23(4):399-406
The problem of conduction modulation of laser radiation is considered. It is shown that acoustic wave interacting with photon field in active medium causes a periodic modulation of the number of quanta in the single-mode gas laser. The problem of modulation is solved quantum mechanically and it is shown that dielectric and conduction modulation give similar results. 相似文献
3.
We consider lattice classical ferromagnetic spin systems at high temperature (1) with nearest neighbor interactions and even single-spin distributions (ssd). Associated with each system is an imaginary time lattice quantum field theory. It is known that there is a particle of mass m–ln in the energy-momentum spectrum. If s
4–3s
22<0, where s
k is the kth moment of the ssd, and is sufficiently small, we show that in the two-particle subspace there is no mass spectrum up to 2m. For >0 we show that the only mass spectrum in (m, 2m) is a bound state of mass m
b=2m+ln(1–)+O(), where =(+2s
22)–1. A bound on the decay of the kernel of a Bethe–Salpeter equation is obtained and used to prove these results. 相似文献
4.
K. Toman 《Czechoslovak Journal of Physics》1961,11(3):186-192
The temperature dependence of the intensity and reflecting range of the (200) reflection of X-rays on an aluminium crystal exhibiting strong primary extinction was studied. It was found that the observed temperature dependence cannot be even approximately expressed by the Debye-Waller factor. The reversible change in the system of imperfections in the crystal is suggested and discussed as a mechanism qualitatively explaining the observed phenomena.
(200) A1
(200) , . , , , -. , .相似文献
5.
Elliott H. Lieb 《Communications in Mathematical Physics》1980,77(2):127-135
A general formulation is given of Simon's Ising model inequality:
whereB is any set of spins separating from . We show that
b
can be replaced by
b
A
whereA is the spin system insideB containing . An advantage of this is that a finite algorithm can be given to compute the transition temperature to any desired accuracy. The analogous inequality for plane rotors is shown to hold if a certain conjecture can be proved. This conjecture is indeed verified in the simplest case, and leads to an upper bound on the critical temperature. (The conjecture has been proved in general by Rivasseau. See notes added in proof.)Work partially supported by U.S. National Science Foundation grant PHY-7825390 A01 相似文献
6.
In a systematic study of the transfer process to sulphur dioxide, in seven different H2 + SO2 gas mixtures, the time spectra of the muonic sulphur X-rays yield muon transfer rates to the SO2 molecule, deduced from the lifetimes of the p atoms, which agree all well with each other. The muonic oxygen time spectra show an additional structure as if p atoms of another kind were present. Reduced transfer ratesO are reproducible if one uses the model of ephemeral p atoms. The intensity ratios between the different kinds of p atoms are also discussed in the framework of this model and the one of black and white p atoms. 相似文献
7.
Ivan Šantavý 《Czechoslovak Journal of Physics》1955,5(3):340-367
, , . , - - . - . -, - , . , - ; , , . 相似文献
8.
In the traditional form of canonical quantization, certain field components (not having conjugate momenta) must be regarded as noncanonical. This long-known distinction enters modern gauge theories, when they are canonically quantized as by Kugo and Ojima. We avoid that peculiarity by not using any conjugate momenta at all. In our formulation, canonical quantization can be related to Feynman's path integral. 相似文献
9.
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%).
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. 相似文献
30% . , . ( 5%).
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. 相似文献
10.
M. Boček 《Czechoslovak Journal of Physics》1960,10(11):830-840
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.
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. 相似文献
: 0, A , B , A A . 226 344°K . A . B . . 0–85°C . , .
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. 相似文献
11.
Arnošt Hladík 《Czechoslovak Journal of Physics》1955,5(4):502-513
- [3], [4], U(x, y) . - U(x, y) -, . B § 10 - . , - , - D, . - . 相似文献
12.
Investigation of aging Cu-1.5% Be-2% Ag and Cu-1% Be-4% Ag alloys was carried out in this study by the methods of x-ray analysis of monocrystals, and electron microscopy. In the aging process at 218, 300, and 450C, laminar zones of Guinier-Preston, enriched with beryllium and silver atoms were formed. Entry of silver into the zones widens the upper temperature interval of the zone stage to 450C. With the increase of annealing time the metastable-phase was precipitated. The crystals of -phase are precipitated with orientation in the direction (100) in consequence of interactions of the fields of elastic stresses occurring around -precipitations, and periodic structure is formed in the alloy. The stable phase-CuBe and Ag was precipitated in the Cu-1% Be-4% Ag-alloy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 21–25, August, 1972. 相似文献
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14.
Alan D. Sokal 《Journal of statistical physics》1981,25(1):25-50
A variety of rigorous inequalities for critical exponents is proved. Most notable is the low-temperature Josephson inequalitydv +2 2–. Others are 1 1 +v, 1 1
, 1,d 1 + 1/ (for d),dv, 3 + (for d), 4 , and 2m 2m+2 (form 2). The hypotheses vary; all inequalities are true for the spin-1/2 Ising model with nearest-neighbor ferromagnetic pair interactions.NSF Predoctoral Fellow (1976–1979). Research supported in part by NSF Grant PHY 78-23952. 相似文献
15.
An experimental investigation is made into the domain structure of cobalt whiskers by the colloid technique. A new type of domain structure was found; the width of the domains is studied as a function of the thickness of the whisker. This dependence follows a two-thirds power law and does not agree with existing theories which predict a half power law.
In conclusion the authors wish to thank V. Janovec and F. Kroupa for valuable remarks and A. Tahalová for help in growing the whiskers. 相似文献
. . , .
In conclusion the authors wish to thank V. Janovec and F. Kroupa for valuable remarks and A. Tahalová for help in growing the whiskers. 相似文献
16.
Vladimír Syneček 《Czechoslovak Journal of Physics》1959,9(6):736-746
An X-ray diffraction method is described for the quantitative determination of the fibre texture in cylindrical specimens (wires), which does not require specimen preparation. The integrated intensity of the diffracted radiation from a certain atomic plane is measured in the direction parallel to the plane determined by the axis of the wire and by the direct beam for different orientations of the axis of the wire. These measurements can be carried out in practice using an X-ray counter diffractometer or Weissenberg goniometer. The pole figure is determined from the dependence of the diffracted intensity on the orientation of the wire after correcting the intensities for the absorption of radiation in the specimen. The geometric arrangement enables the absorption factor to be calculated analytically. Its form was verified experimentally by measuring the dependence of the intensity of the 220 reflection on the orientation of the axis of a cylindrical specimen of Al containing randomly oriented crystals.
The author wishes to thank Z. iký for help in carrying out the measurements and calculations. 相似文献
I.
( ), . , , , . . , . . 220 .
The author wishes to thank Z. iký for help in carrying out the measurements and calculations. 相似文献
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18.
The dependence of the critical resolved shear stress of zinc single crystals on the impurity content and the dislocation density is observed. It is shown that the effect of impurities on the critical resolved shear stress is indirect.
. , .相似文献
19.
Vladimír Dvořák 《Czechoslovak Journal of Physics》1959,9(6):710-716
The possibility of explaining the existence of a surface layer on BaTiO3 crystals by the presence of Schottky defects in the crystal is investigated. The magnitude of the potential difference between the surface and the interior of the crystal and the thickness of the surface layer, which at temperatures of over 400°C agrees with the measured values, are calculated for the cubic phase from a simplified ionic model.
In conclusion the author would like to thank Dr. M. Trlifaj and V. Janovec, candidates of physics and mathematics, for valuable remarks. 相似文献
BaTiO3
iO3 . , 400° .
In conclusion the author would like to thank Dr. M. Trlifaj and V. Janovec, candidates of physics and mathematics, for valuable remarks. 相似文献
20.
Z. Šroubek 《Czechoslovak Journal of Physics》1961,11(9):634-643
The theory of double quantum transitions of the M=±2 type, with regard to inhomogeneously broadened spin systems is studied in this paper with the approximation
2T2T3 1. We suppose that the inhomogeneous broadening is formed by an inhomogeneous crystal field. The obtained results describe the magnitude of absorption as a function of the h.f. power and also describe the shape of the absorption curve. It is demonstrated that in inhomogeneously broadened spin systems the absorption curve of double quantum transitions has the form of the difference of two different Lorentz's curves and that at the saturation (
2T2T1 1) the absorption increases with the cube of the h.f. field intensity. The shape of the curves is expressed by means of phenomenological relaxation constants of the system.
M=±2 2T2T3 1. , - . . , ( 2T2T1 1) . .相似文献