Refined technique for susceptibility resolution into ferromagnetic and paramagnetic components based on susceptibility temperature-variation measurement   总被引：2，自引：0，他引：2  

Franti&#;ek Hrouda    Vit Jelínek  Karel Zapletal 《Geophysical Journal International》1997,129(3):715-719

The measurement of the temperature variation of magnetic susceptibility can be used for the separation of ferromagnetic and paramagnetic susceptibility components. The method suggested by Hrouda (1994) assumes a hyperbolic dependence of paramagnetic, susceptibility and constant ferromagnetic susceptibility in the temperature interval used for the separation. Our new method works with a paramagnetic hyperbola again, but assumes that the ferromagnetic susceptibility temperature variation is represented by a linear relationship in the resolution interval, as indicated by the investigation of monomineralic ferromagnetic fractions.  相似文献   

Self-reversal of isothermal remanent magnetization in a pyrrhotite (Fe₇S₈) crystal     

Karel Zapletal 《Physics of the Earth and Planetary Interiors》1992,70(3-4):302-311

The remanent magnetization induced at room temperature (IRM) was measured for powder and massive specimens separated from a Fe₇S₈ crystal. To characterize the crystal, several methods were used including Mössbauer spectroscopy, thermomagnetic analysis, low-field susceptibility anisotropy and magnetic colloid method. Self-reversals of IRM were revealed in the massive crystal fragment after its magnetization in magnetic fields of the order of 10–10² mT. Both normal and reverse IRM vectors lay in the maximum susceptibility plane perpendicular to the crystallographic c′-axis of the crystal. A twinning also perpendicular to the crystal's c′-axis and a very low coercivity in each twin (monocrystallic layer) probably support the origin of the reverse IRM in the crystal.  相似文献   

On the mathematical modelling of the spectral structure of geomagneticPC1 pulsations via the response of Alfvén's ionospheric resonator     

Karel Prikner  Felix Z. Feygin  Dora S. Fligel 《Studia Geophysica et Geodaetica》1995,39(1):19-36

Summary A method of numerical simulation of the coefficient of reflection of the ionospheric transition layer as a function of frequency is applied to the experimental data related to several series of pearl-type pulsations Pc1 (f = 0.2 – 2 Hz) recorded at the observatories of Kerguelen, Sogra and Nurmijarvi. The inverse problem of modelling, i.e. determining the vertical profiles of ionospheric electron concentration corresponding to the actual experimental situations, was solved approximately. The initial assumption for interpreting the specific nature of the series of Pc1 micropulsations parallel in time was their resonance origin under reflection of the signal at magnetically conjugate ionospheres, Alfvén's resonators, in both of the Earth's hemispheres.  相似文献   

Narrowband dm-spikes in the 2 GHz frequency range and MHD cascading waves in reconnection outflows   总被引：1，自引：0，他引：1  

Marian Karlický  Michal Sobotka  Karel Jiřička 《Solar physics》1996,168(2):375-383

Two examples of clouds of narrowband dm-spikes, observed by the Ondejov radiospectrograph in the 1–2 GHz frequency range, are analyzed. After transformation of the frequency scales to distances in the solar atmosphere, the power spectra analysis of size scales reveals a spectral index of –5/3, resembling that of Kolmogorov spectra of turbulent cascades. The narrowband dm-spikes are interpreted as radio emission from electrons accelerated in MHD cascading waves, probably generated in plasma outflows from magnetic field reconnection.  相似文献   

Determination of the Geopotential Scale Factor from TOPEX/POSEIDON Satellite Altimetry     

Burša  Milan  Raděj  Karel  Šima  Zdislav  True  Scott A.  Vatrt  Viliam 《Studia Geophysica et Geodaetica》1997,41(3):203-216

The geopotential scale factor R _o = GM/W _o (the GM geocentric gravitational constant adopted) and/or geoidal potential Wo have been determined on the basis of the first year's (Oct 92 – Dec 93) ERS-1/TOPEX/POSEIDON altimeter data and of the POCM 4B sea surface topography model: R _o °=(6 363 672.58°±0.05) m, W _o °=(62 636 855.8°±0.05)m ² s ^–2 . The 2°–°3 cm uncertainty in the altimeter calibration limits the actual accuracy of the solution. Monitoring dW _o /dt has been projected.  相似文献   

Error Propagation in Isometric Log-ratio Coordinates for Compositional Data: Theoretical and Practical Considerations     

Mehmet Can Mert  Peter Filzmoser  Karel Hron 《Mathematical Geosciences》2016,48(8):941-961

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A contribution to the historical climatology of morocco and mauritania     

Karel Pejml 《Studia Geophysica et Geodaetica》1962,6(3):257-280

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The velocity of elastic waves in diabase and greywacke under pressures up to 4 kilobars     

Zdeněk Pros  Jiří Vaněk  Karel Klíma 《Studia Geophysica et Geodaetica》1962,6(4):347-368

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Application of the method of numerical simulation of ionospheric filtration of Pc1 signals to solving the inverse problem of ionospheric modelling     

Karel Prikner  Dora S. Fligel 《Studia Geophysica et Geodaetica》1992,36(3):240-256

Summary The numerical method of simulating ionospheric filtration of ULF signals in the range of Pc1 frequencies has been applied to French geomagnetically conjugate observations of ULF signals made by the GEOS-1 satellite and at the observatory of Husafell (Iceland) [2]. The experimentally obtained variable values of the transmissivity of the Pc1 signal through the ionosphere [5] in the course of the micropulsation distrubance of 13.7. 1977 have been compared with the results of the numerical simulation taking into consideration the fundamental physical parameters of the high-latitude external ionosphere. This approximate form of solving the inverse problem of ionospheric modelling yielded quantitative estimates of the rapid variations of the concentration of charged particles in connection with the expected changes of their temperature. It is assumed that nonstationary states of the ionospheric plasma are caused by the very ion-cyclotron waves penetrating the ionosphere at high latitudes ( 70°) along the plasmapause.  相似文献   

Detailed spatio‐temporal sediment supply reconstruction using tree roots data          下载免费PDF全文

Karel Šilhán  Tomáš Galia  Václav Škarpich 《水文研究》2016,30(22):4139-4153

Floods are an important geomorphic agent that accelerate sediment supply from bank failures. The quantitative proportions supplied by lateral inputs and the transport conditions of the channel can create local or extended accumulation zones within the channel reaches. These accumulation zones play an important role in the geomorphic regime of the stream. Knowledge of long‐term history of sediment supply is necessary to determine how these input and deposition forms developed. This study introduces a new approach for the quantification of past sediment supply via lateral erosion (incised banks and individual bank failures), using a case study of the confluence of three partial tributaries in the accumulation zone in the Outer Western Carpathians. For each tributary, as well as the channel reach downstream of the confluence zone, we calculated the mean of the largest bed particles and the unit stream power as indicators of transport capacity. We found that two of the tributaries supply significant amounts of sediment to the accumulation zone because of their higher unit stream power related to their higher transport potential, and observed coarser bed sediment. Seventy‐three bank failures with a total volume 395.5 m³ were mapped, and the sediment supply volume was dated using dendrogeomorphic analysis of 114 scarred tree roots (246 samples). The total volume of the dated sediment supply in the individual tributaries was 193.9 m³, whereas the volume of erosion in the accumulation zone was only 4.9 m³ for a period of approximately 30 years. The period represented by the dated tree roots included 12 years in which erosion events occurred and impacted the total sediment budget in the study area. Although sediment supply was greater than erosion in the accumulation zone, there are no present‐day signs of accretion. The rupture of a dam in an old pond (which is situated approximately 50 m below the accumulation zone) probably increased the transport conditions in the accumulation zone so that it balanced the high sediment supply from individual tributaries. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献