Frequency modified fourier transform and its application to asteroids     

Miloš Šidlichovský  David Nesvorný 《Celestial Mechanics and Dynamical Astronomy》1996,65(1-2):137-148

Recently a method has been suggested to analyze the chaotic behaviour of a conservative dynamical system by numerical analysis of the fundamental frequencies. Frequencies and amplitudes are determined step by step. As the frequencies are not generally orthogonal, a Gramm-Schmidt orthogonalization is made and for each new frequency the old amplitudes of previously determined frequencies are corrected. For a chaotic trajectory variations of the frequencies and amplitudes determined over different time periods are expected. The change of frequencies in such a calculation is a measure of the chaoticity of the trajectory. While amplitudes are corrected, the frequencies (once determined) are constant. We suggest here simple linear corrections of frequencies for the effect of other close frequencies. The improvement of frequency determination is demonstrated on a model case. This method is applied to the first fifty numbered asteroids.  相似文献   

Capture of dust grains in exterior resonances with planets     

Milo idlichovský  David Nesvorný 《Earth, Moon, and Planets》1995,71(3):175-178

The temporary capture of the dust grains in the exterior resonances with planets is studied in the frames of the planar circular three-body problem with Poynting-Robertson (PR) drag. For the Earth and particles ~ 10 m the resonances 4/5, 5/6, 6/7, 7/8 are shown to be most effective. The capture is only temporary (of order 10⁵ years) and the position of resonance may be calculated from semi-analytical model using averaged disturbing function. These semi-analytical results are confirmed by numerical integration. For various planet this picture changes as with increasing planetary mass the more exterior resonances become more important. We showed that for Jupiter (at least in the space between Jupiter and Saturn) the resonance 1/2 plays the dominant role. The capture time is here several myr but again eccentricity is evolving to eccentricity e ₀ ~ 0.48 of libration point for this resonance.  相似文献   

Comprehending conodonts          下载免费PDF全文

Milo Barham 《Geology Today》2015,31(2):74-80

Conodonts were small, thin, elongate jawless creatures that were a common component of the marine fauna from the late Cambrian, throughout the Palaeozoic and into the Triassic. For the majority of conodont research history, speculations on conodont affinity were restricted to the histology and arrangement of their mineralized tissues—‘conodont elements’. These conodont elements comprise millimetre‐scale phosphatic microfossils that superficially resemble teeth, and are commonly recovered from the residues of appropriately aged, disaggregated sedimentary rocks. It has only been in the last three decades, since the discovery of exceptionally preserved soft tissues, that the debate on conodont affinity has been refined, though it has hardly been less vigorously debated. Despite being studied extensively for over more than a century and a half, conodonts retain significant enigmatic qualities. Although many geologists today are familiar with the name, knowledge of conodont biology and ecology are often surprisingly lacking or confused, and conodonts remain as largely disembodied microfossil curiosities. Despite this, conodont elements are extensively and variously used in biostratigraphy, thermal maturation studies and palaeoenvironmental reconstructions, while conodonts themselves occupy a potentially critical position in the evolutionary tree of our own phylum—the chordates.  相似文献   

Modeling Urban Land Use Changes Using Support Vector Machines          下载免费PDF全文

Mileva Samardžić‐Petrović  Suzana Dragićević  Miloš Kovačević  Branislav Bajat 《Transactions in GIS》2016,20(5):718-734

Support Vector Machines (SVM) is a machine learning (ML) algorithm commonly applied to the classification of remotely sensing data and more recently for modeling land use changes. However, in most geospatial applications the current literature does not elaborate on specifications of the SVM method with respect to data sampling, attribute selection and optimal parameters choices. Therefore the main objective of this study is to present and investigate the SVM technique for modeling urban land use change. The SVM model building procedure is presented together with the detailed evaluation of the output results with respect to the choice of datasets, attributes and the change of SVM parameters. Geospatial datasets containing nine land use classes and spatial attributes for the Municipality of Zemun, Republic of Serbia were used for years 2001, 2003, 2007 and 2011. The Correlation‐based Feature Subset method, kappa coefficient, Area Under Receiver Operating Characteristic Curve (AUC) and kappa simulation were used to perform the model evaluation and compare the model outputs with the real land use datasets. The obtained results indicate that the SVM‐based models perform better when implementing balanced data sampling, reduced data sets to informative subsets of attributes and properly identify the optimal learning parameters.  相似文献   

Einfluss Eines der Systematischen Fehler bei der Geographischen Breitebestimmung Auf Die Form des Geoides     

Miloš Pick 《Studia Geophysica et Geodaetica》1960,4(3):205-216

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Über Das Problem der Transformation Eines Referenzellip-Soid auf ein Anderes Mittels Projektion Längs der Normalen     

Miloš Pick 《Studia Geophysica et Geodaetica》1957,1(2):372-375

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Recent movements of the earth's crust     

Miloš Pick  Reviewer M. Cimbálník 《Studia Geophysica et Geodaetica》1973,17(3):253-254

Summary It has been shown that it is necessary to combine several methods to be able to describe and explain recent movements of the Earth's crust.Presented at the XV^th General Assembly of the IUGG, Moscow 1971.  相似文献   

Isoseismals of the strongest Friuli aftershocks of September 1976     

Vít Kárník  Dana Procházková  Zdeňka Schenková  Julius Drimmel  Dieter Mayer-Rosa  Dragutin Cvijanovic  Vladimir Kuk  Andelka Miloševič  Francesco Giorgetti  Reviewer J. Janský 《Studia Geophysica et Geodaetica》1978,22(4):411-414

Summary Isoseismal maps of the three strongest Friuli aftershocks of September 1976 were compiled using the contributions from European countries within the shaken area. The characteristic features of the macroseismic fields are discussed.  相似文献   

Berechnung des Brechungswinkels Mittels des Brechungsindex     

Miloš Pelikán 《Studia Geophysica et Geodaetica》1964,8(3):209-238

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Mineral and chemical composition of the new iron meteorite Javorje from Slovenia     

Miloš MILER  Mateja GOSAR 《Meteoritics & planetary science》2011,46(12):1939-1946

Abstract– The single‐piece iron meteorite Javorje, with a mass of 4920 g, is the heaviest and largest meteorite found in the territory of Slovenia. The meteorite Javorje is a medium octahedrite with kamacite bandwidth of 0.85 ± 0.26 mm. The bulk composition of Ni (7.83 wt%), Co (0.48 wt%) and trace elements Ga (25 μg/g), Ge (47 μg/g), Ir (7.6 μg/g), As (5.8 μg/g), Au (0.47 μg/g), and Pt (13.4 μg/g) indicates that the meteorite Javorje belongs to the chemical group IIIAB. Mineral and bulk chemical compositions are consistent with other reported group IIIAB meteorites. The presence of numerous rhabdites, carlsbergite, sparse troilite, and chromite and abundance of daubréelites are in accordance with low‐Ni and low‐P IIIAB iron meteorites. The severely weathered surface and secondary weathering products in the interior of the meteorite suggest its high terrestrial age.  相似文献