Application of the photoacoustic method for characterization of natural galena (PbS)     

P. M. Nikolić  S. Ðurić  D. M. Todorović  D. Vasiljević-Radović  V. Blagojević  P. Mihajlović  J. Elazar  K. T. Radulović  A. I. Bojičić  D. Urošević 《Physics and Chemistry of Minerals》2001,28(1):44-51

Electron transport properties of single crystal and polycrystalline natural mineral galena (PbS) samples from the Trep?a mine, Yugoslavia, were determined using the photoacoustic frequency transmission technique. Their thermal diffusivity (D _T≈0.16 × 10^?5 m² s^?1), the coefficient of diffusion (D between 0.15×10^?2 0.16×10^?2 m² s^?1) and lifetime of the excess carrier (τ≈35 μs and the front and rear recombination velocity (s _g≈65.5 m s^?1 and s _b≈66.4 m s^?1, respectively), were calculated by comparing the experimental results and the theoretical photoacoustic amplitude and phase signals. The lattice parameter obtained by X-ray work was a?=5.936?Å. The free carrier concentration of these single-crystal samples was measured using the Hall method (N?=?3×10¹⁸ cm^?3). Measurements of the optical reflectivity of the same samples, as a function of wavelength, in the infrared and far infrared ranges, were performed. In the far infrared range a free electron plasma frequency was observed and numerically analyzed, using the least-squares fitting procedure. The values of optical parameters were calculated and the value of the free carrier concentration obtained by the Hall method was confirmed.  相似文献   

Über die Überlagerungsgeschwindigkeit der Fronten     

M. Čadež 《Pure and Applied Geophysics》1960,45(1):227-237

Summary One can find that over the continent the cold fronts becomes stationary after the sunrise. In the present paper this phenomen is explaned by heating of cold air what causes the increase of the slope of the boundary surface. Because of surface heating of the cold air the horizontal pressure gradient in direction toward the front increases with time, and so increases the transport of the cold air in this direction too. The increasing of the slope of boundary surface that is in connection with the mentioned increased trasport of cold air, causes the convergence of air mass and the ascent of it at the same front (Fig. 2).As the consequence of the heating from the surface and the liberation of latent heat of vaporisation, the volume of cold air increases. In connection with this the divergence of mass occures in the high levels and later one can find at the surface the corresponding fall of pressure. This effects can cause in suitable cases the development of cyclon, similarily as shown on Fig. 4. When the cold air comes from the cold continent over a relatively warm sea surface, the strong heating of cold air occurs and as consequence of this, the cyclogenesis.  相似文献   

The chromospheric flare effect in atmospherics (IGY 1957)     

Ladislav Křivský  Blažena Råžičková 《Studia Geophysica et Geodaetica》1959,3(2):154-164

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Numerical model for quantitative precipitation forecasting     

Djuro Radinović 《Pure and Applied Geophysics》1972,93(1):159-176

Summary A numerical model for the quantitative precipitation forecasting has been formulated. In this model precipitation is computed as a function of the vertical velocity and humidity distribution in the atmosphere. The orographic influence on the vertical velocity was taken into consideration. Further, the relation between vertical velocity and static stability of the atmosphere has been considered and, as an important factor in the condensation process, was introduced into the equation of the model. This numerical model for the precipitation forecasting has been applied in the North Adriactic Sea region, which is characterized by a strong vertical gradient of the specific humidity and pronounced orographic influence. The results achieved show that this model could successfully be used as an objective method in the routine forecasting of the amount of precipitation.  相似文献   

Frequency analysis of geomagnetic beating-type pulsations in thepc3 range     

Karel Prikner  Jaroslav Střeštík  Karel Dobeš  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1972,16(3):262-270

Summary The spectral analysis of samples of beating-type pc3 pulsations, recorded at the Budkov Observatory during the summer months of 1968 and 1969 was carried out in the frequency interval10 mHz100 mHz. The average limits of the pulsation frequency range are roughly20 mHz60 mHz. The centre of the occurrence frequency graphs for both components is at the frequency f_g 41 mHz. The analysis of three separated daily intervals showed a very slight tendency to a systematic decrease in the frequency of the centre from the morning to the afternoon. The study of the sense of rotation of the pulsation disturbance vector in the (X, Y)-plane showed an overall predominancy of L over R-types during daytime, particularly during the morning.  相似文献   

Electromagnetic induction in a half-space with a cylindrical inhomogeneity     

Milan Hvoždara  Reviewer O. Praus 《Studia Geophysica et Geodaetica》1972,16(3):240-261

Summary The problem of electromagnetic induction in a half-space with a cylindrical inhomogeneity is treated. Solutions for TE and TM polarization of the exciting electromagnetic field are given, which can be used for computing sounding and profiling curves. The anisotropy of the surface impedance is pointed out, as well as a whole series of other interesting properties of the magnetotelluric field in this model; some of them are also demonstrated on the computed theoretical curves.  相似文献   

Study of the induction arrow at budkov (Czechoslovakia)     

Oldřich Praus  Jindřich Rejl  Reviewer M. Hvoždara 《Studia Geophysica et Geodaetica》1972,16(4):373-382

u¶rt;m mam u¶rt;au m ¶rt;a u¶rt;u ma u n aau anu mauaum n amuu ¶rt; a nu¶rt; 1967–1970. aamua ma auum m u¶rt;uu m nu¶rt;a u u am ¶rt;am a¶rt;a m mu ¶rt;¶rt;m -3 amu aua.

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Dedicated to Academician Alois Zátopek on His 65th Birthday  相似文献   

Way of flying based on compressibility of fluids     

Marjan Čadež 《Pure and Applied Geophysics》1972,93(1):187-190

Summary The forces due to compressibility of a fluid and their action on moving bodies have been studied. Also a possible practical application of these forces in a propulsion mechanism for vehicles has been discussed.

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Zusammenfassung Im vorliegenden Beitrag wird die Wirkung der Kräfte auf bewegende Körper, die durch Kompressibilität des Mediums bedingt sind, untersucht. Es wird über die Möglichkeit der Konstruktion eines Mechanismus auf diesem Prinzip diskutiert.

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On the problem of frequency calibration of induction variometers with large air-core loops     

Josef Bochníček  Jaroslav Šubrt  Reviewer M. Hvoždara  Reviewer J. Podlešák 《Studia Geophysica et Geodaetica》1971,15(1):76-85

Zusammenfassung Es wird eine Methode für experimentelle Untersuchung der Frequenzkennlinien von Induktionsvariometern mit Aufnahmeschleifen nichttraditioneller Ausmasse beschrieben. Die Grundlage des beschriebenen Verfahrens bildet eine genaue Bestimmung jenes Teils des magnetischen Kraftflusses, der durch die Aufnahmeschleife durchgeht.  相似文献   

Dolomitmarmor in der Umgebung der Stadt Prilep und die in ihm vorkommenden Minerale     

Lj. Barić 《Mineralogy and Petrology》1969,13(3-4):233-249

Zusammenfassung In der Umgebung der Stadt Prilep in Mazedonien kommen an mehreren Stellen in einer hochmetamorphen, aus Glimmerschiefern und Amphiboliten bestehenden Zone Calcit- und Dolomitmarmore vor. In den letzterwähnten wurden bisher Dolomit, Calcit, Korund, Diaspor, -Zoisit, Rutil, Fluorit, Achroit, Pyrit, Muskovit, Illit, Margarit und Chlorit (vonErdmannnsdörfer auch Kossmatit) festgestellt. Diese Paragenese ist regionalmetamorph entstanden.

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Dolomite-marble in the surroundings of the town prilep, macedonia, and its minerals

Summary Calcite- and dolomite-marbles occur in a highly metamorphic series together with micaschists and amphibolites at several localities in the surroundings of Prilep, Macedonia. In the dolomite-marbles, dolomite, calcite, corundum, diaspore, -zoisite, rutile, fluorite, achroite pyrite, muscovite, illite, margarite, chlorite, and kossmatite (the last only byErdmannsdörffer) have been found. The paragenesis is of regional metamorphic origin.

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Mit 1 Abbildung  相似文献