Modelling magnetization processes in single-and multi-domain rock samples using the preisach diagram     

Pavel Hejda  Vladimír Kropáček  Tomáš Zelinka 《Studia Geophysica et Geodaetica》1990,34(3):220-229

Summary The paper presents the results of identifying a model of the Preisach type for haematite grains of the single-domain as well as multi-domain size. Due to the phenomenological conception of the model, the relations between the parameters of the model and actual parameters are very complex, however, impressive accuracy and stability of the modified model indicate the need to resume studies of this problem. The model parameters also confirm the adequate properties of the vibrating-sample magnetometr (VSM) used and developed in our laboratories.  相似文献   

Quantitative analysis of travel-time curves of seismic events in the Ostrava-Karviná coal mining district     

Jiří Slavík  Pavel Kalenda  Karel Holub 《Studia Geophysica et Geodaetica》1991,35(3):234-243

Summary The paper is intended as a contribution to the quantitative analysis of travel-time curves of seismic events recorded in the Ostrava-Karviná District (OKD). The input data represent a set of 2621 seismic events, recorded by the local seismological network of 26 mine stations DSLA and a regional diagnostic polygon consisting of five surface Lennartz stations. All the events were processed automatically in the Operational Seismological Centre of the Czechoslovak Army Mine in Karviná and stored in the seismological data base. The results are presented in the form of graphs of arrival times versus distance for the whole OKD, for two mines and one tectonic block.Travel-time curves of direct P and S waves, as well as of reflected and refracted waves are given. The direct P and S waves propagate well practically throughout the whole region studied, but their apparent velocities of propagation are affected by the properties of the rock medium.As a result of the complicated geological conditions, the recorded wave image is quite complicated. Methods of mathematical modelling, using kinematic and dynamic parameters of seismic waves, will have to be applied to identify the separate wave groups uniquely.  相似文献   

Total ozone response to major geomagnetic storms and changes in meteorological situations     

Pavel Mlch  Jan Laštovička 《Studia Geophysica et Geodaetica》1995,39(2):189-207

Summary The total ozone response to strong major geomagnetic storms (A_p≥60) in winter along the 50° N latitudinal circle is studied. The results add to the recent results of Laštovička et al. (1992) obtained for European middle latitudes (∼50°N) and to the results of Mlch (1994). A significant response of total ozone is only observed in winter under high solar activity/E-phase of QBO conditions (E-max) and seems to be caused by geomagnetic storm-induced changes of atmospheric dynamics. There are two sectors along latitude 50°N, which are sensitive to forcing by geomagnetic storms both in total ozone and the troposphere — north-eastern Atlantic-European and eastern Siberia-Aleutian sectors. The total ozone response under E-max conditions manifests itself mainly as a large decrease in the longitudinal variation of ozone after the storm, which means an increase of ozone in Europe. The observed effects in total ozone consist in redistribution, not production or loss of ozone.  相似文献   

The map of vertical crustal movements in Czechoslovakia and its interpretation     

Jn Vanko  Pavel Vysko il 《Journal of Geodynamics》1987,8(2-4)

In addition to the measurements carried out in the framework of the 1973–1978 international relevellings, further levelling lines have been remeasured on the territory of Czechoslovakia till now. Considering all new relevellings on the region under study, an independent adjustment of annual velocities of vertical movements in whole network was performed. The values of vertical movements were determined relatively to the fundamental benchmark Želešice in the central part of Czechoslovakia, monumented in the bedrock of the southeastern border of the Bohemian Massif. The results are presented in a map of vertical movements and preliminarily interpreted in connection to the geological features of the territory under study.  相似文献   

The dynamics of the northwestern border of the Carpathians     

Pavel Vysko il 《Journal of Geodynamics》1987,8(2-4)

The border area between the Bohemian Massif and the Carpathians arc is covered by dense networks of repeated levellings as well as horizontal (triangulation, trilateration) measurements. The results were adjusted in separate vertical or horizontal networks respectively. Derived rates of vertical and horizontal movements are presented. The properties of these movements are discussed as a background to the tectonic development of the area under study.  相似文献   

Boundary conditions in the hydromagnetic dynamo problem     

Pavel Hejda  Reviewer G. Siráň 《Studia Geophysica et Geodaetica》1982,26(4):361-372

au am nu¶rt;, nuau ¶rt;u¶rt;aum ¶rt;ua, a u ¶rt; ma aum u¶rt;uu aam ma¶rt;am . a a au ¶rt; uuauu u nm nmu a u m muna, mm m¶rt; ma a anma n u. uunua muau u m¶rt; nua [4, 5]. n¶rt; am nuam m¶rt; u, u¶rt;u u m¶rt;a a u a nm nu nu¶rt;um au m u m¶rt;.  相似文献   

Latitude variation of the LHR frequency in the outer ionosphere as an indicator of the degree of magnetospheric perturbance     

Jaroslava Bošková  František Jiřiček  Pavel Tříska  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1983,27(3):298-304

  相似文献   

Whistler-mode propagation of omega VLF navigation signals as observed on board of satellites     

František Jiříček  Pavel Tříska  Reviewer S. Fischer 《Studia Geophysica et Geodaetica》1983,27(4):393-407

  相似文献   

Curvature and non-resonance Compton gamma-ray emission of a radio pulsar with a non-dipolar magnetic field     

D. P. Barsukov  E. M. Kantor  A. I. Tsygan 《Astronomy Reports》2007,51(6):469-476

We consider the influence of a non-dipolar magnetic field on the gamma-ray emission from the polar regions of a radio pulsar. The pulsar is treated in a Goldreich-Julian model with a free flow of charge from the surface of the neutron star. When finding the intensity of the gamma-ray radiation of the pulsar tube, both curvature gamma-ray radiation from the primary electrons and non-resonance inverse Compton scattering of thermal photons from the polar cap on primary electrons are taken into account. When finding the height of the upper plate of the pulsar diode, we included only positrons created by the curvature radiation of primary electrons. We assumed that the polar cap is heated by the return positron current. The influence on the gamma-ray emission of variations in both the radius of curvature of the magnetic force lines and in the electric field due to the non-dipolarity of the magnetic field were taken into account. The presence of even weak non-dipolarity of the magnetic field leads to a sharp decrease in the intensity of the gamma-ray emission from the pulsar tube at energies 1–100 MeV, while the intensity of the inverse Compton radiation (at energies 1–100 GeV) varies only relatively weakly.  相似文献   

Chemical composition and physical properties of lithium-iron micas from the Krušné hory Mts. (Erzgebirge)     

Milan Rieder  Miroslav Huka  Dagmar Kučerová  Luděk Minařík  Jiří Obermajer  Pavel Povondra 《Contributions to Mineralogy and Petrology》1970,27(2):131-158

Compositions of natural lithium-iron micas are approximated best by the sidero-phyllite-polylithionite join. These micas contain little or no magnesium and manganese. Their octahedral sheets contain close to two trivalent cations (mainly aluminum) in small crystallographic sites and a variable quantity of lithium and R⁺² (mainly iron) in large sites. Octahedral vacancies are situated mostly in large sites. Lithium and R⁺² approach a 44 replacement relationship in micas with octahedral occupancy close to six. Lithium and fluorine show a good positive correlation (small excess of fluorine over lithium), which indicates a crystallochemical association between them. There is a less distinct positive correlation between lithium and R⁺⁴.Based on simplifications, a calculation shows that about two-thirds of octahedral vacancies are caused by substitutions within the octahedral sheet, one-third, by tetrahedral substitutions. Different methods of calculating the crystallochemical formula yield slightly different numbers of octahedral vacancies, but do not affect the mica's position in plots of physical parameters against composition. If a crystallochemical formula is calculated from analysis of a mica contaminated with quartz, topaz, or feldspar, the apparent number of octahedral vacancies increases; such a formula exhibits unusual behavior in composition plots.  相似文献