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151.
Karel Diviš Vladimír Tobyáš Bohumil Chán Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1989,33(2):206-209
Summary A model, explaining the effect of air pressure changes in the space of the measuring system on the fine dial counter constant of the Worden and similar gravity meters, is presented. It is based on the changes of the bellows volume with compensating the gravity changes. It is shown that the resetting the gravity meter in the whole range has practically no influence on the fine dial counter constant.
u¶rt;a ¶rt;, na m uu ¶rt;au ¶rt;a nmam uum um a nm a umaauma ¶rt; u nuaum. ¶rt; aa a uu a ua umu uma nu nauu uu u mmu. aa, m nma ¶rt;uanaa um namuu um a uu nm a uma.相似文献
152.
The study discusses the potential of various histological methods for enhancing the readability of the lines of arrested growth
(LAC, annuli) in different bony elements, particularly fin rays, of some freshwater fish species.
相似文献
153.
Sphalerite stars in chalcopyrite: Are they always the result of an unmixing process? 总被引:1,自引:0,他引:1
Ch. Marignac 《Mineralium Deposita》1989,24(3):176-182
Sphalerite skeletal crystals in inclusions in chalcopyrite (so-called sphalerite stars) are widely thought to be the result of high-temperature unmixing processes. Detailed observations in the chalcopyrite ores at Aïn Barbar (Algeria) demonstrate that the unmixing theory cannot work in this case. It is here proposed that skeletal crystals are the result of a local supersaturation in sphalerite at the growing fronts of chalcopyrite. This implies a high precipitation rate, estimated to be ca. 10-6 m sec-1, remaining compatible, however, with a recharge in ore-forming components by the flowing mineralizing solutions. In addition to Aïn Barbar, this explanation is probably of more general significance since the kind of relationships described here is by no means restricted to this particular deposit. 相似文献
154.
G. Cortecci J. Ch. Fontes A. Maiorani G. Perna E. Pintus B. Turi 《Mineralium Deposita》1989,24(1):34-42
This paper deals with barite from stratiform, karst, and vein deposits hosted within Lower Paleozoic rocks of the Iglesiente-Sulcis mining district in southwestern Sardinia. For comparison sulfates from mine waters are studied. Stratiform barite displays 34S=28.8–32.1, 18O=12.7–15.6, and 87Sr/86Sr=0.7087, in keeping with an essentially Cambrian marine origin of both sulfate and strontium. Epigenetic barite from post-Hercynian karst and vein deposits is indistinguishable for both sulfur and oxygen isotopes with 34S=15.3–26.4 and 18O=6.6–12.5; 87Sr/86Sr ratios vary 0.7094–0.7140. These results and the microthermometric and salinity data from fluid inclusions concur in suggesting that barite formed at the site of mineralization by oxidation of reduced sulfur from Cambrian-Ordovician sulfide ores in warm, sometimes hot solutions consisting of dilute water and saline brine with different 18O values. The relative proportion of the two types of water may have largely varied within a given deposit during the mineralization. In the karst barite Sr was essentially provided by carbonate host rocks, whereas both carbonate and Lower Paleozoic shale host rocks should have been important sources for Sr of the vein barite. Finally, 34S data of dissolved sulfate provide further support for the mixed seawater-meteoric water composition of mine waters from the Iglesiente area. 相似文献
155.
Summary Since early experiments by Renard and Clarke in 1965 there has been until now no essential progress in numerical frontal analysis. To overcome the frequent lack of agreement of frontal analysis between different analysts and weather bureau centers an objective frontal analysis model seems to be necessary. Therefore an attempt will be made to develop an algorithm to analyse fronts in relation to their location, type and activity by a numerical method.With 12 Fugures 相似文献
156.
Inversion of gravity and magnetic anomalies over some bodies of simple geometric shape 总被引:1,自引:0,他引:1
The general expression for gravity and magnetic anomalies over thin sheets and sloping contacts may be expressed as a polynomial of the formFx
2+C1Fx+C2F+C3x3+C4x2+C5x+C6. The initial parameters of the source are obtained from the coefficientsC
1, C2,..., C6 which may be solved by inverting a 6×6 matrix. The initial parameters are modified by successive iteration process using the difference formula until the root mean square error between the observed and calculated anomalies is a minimum. The regional background which may be in the form of a polynomial is estimated by the computer itself. This method is applied on a number of field anomalies and is found to yield reliable estimates of depth and other parameters of the source. 相似文献
157.
158.
159.
Papazachos B. C. Papadimitriou E. E. Kiratzi A. A. Papaioannou Ch. A. Karakaisis G. F. 《Pure and Applied Geophysics》1987,125(4):597-612
Repeat times of large shocks are obtained for 17 seismic fracture zones of the Aegean and surrounding area, from times of historic and present century earthquakes. The mean standard deviation of the repeat times is approximately 50% of any one observation.A probabilistic approach is then used to forecast the likelihood of large future earthquakes in each fracture zone, using as input the time of the last large shock, the average repeat time and its standard deviation. Shallow and intermediate depth earthquakes are examined separately. The calculated probabilities are high for the entire Hellenic arc, both for shallow and intermediate depth seismicity, for the area of Leucas island (Ionian), of Lesbos island (Aegean), for Patraikos-west Corinthiakos Gulfs, for Evoikos Gulf as well as for southern Bulgaria.The probability estimates based on the most recent large earthquakes, involve a number of basic physical assumptions and we would think that they provide a semi-stochastic approach to the problem of earthquake prediction in Greece. 相似文献
160.
Numerical experiments of fictitious small bodies with initial eccentricities e=0.1 have been performed in the overlapping region of the 3/1 mean motion resonance and of thev
6 secular resonance 2.48a2.52AU for different values of the initial inclination 16°i20°. An analysis for thev
6 secular resonance shows that the topology is different from the one found outside the overlapping region: the critical argument for thev
6 resonance in the overlapping region rotates in opposite direction as compared to the purev
6 region. In the 3/1 resonance region the secular resonancev
5 is dominant, and some secondary secular resonances asv
6 –v
16 andv
5 +v
6 are present. 相似文献