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Dinoflagellate cysts and palynofacies across the Cretaceous-Paleogene boundary interval of the Vrancea Nappe (Eastern Carpathians, Romania)

Țabără D., Slimani H.

Geological Quarterly

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2017

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Vol. 61, No. 1

39--52

EN

A palynological study of uppermost Maastrichtian to Lower Paleocene depos i ts from a stratigraphic section of the Vrancea Nappe (Eastern Carpathians), reveals the presence of diverse and well-preserved dinoflagellate cyst assemblages. The biostratigraphic interpretation of these dinocyst assemblages suggests that (1) the Cretaceous-Paleogene boundary lies within a ~8 m thick sedimentary interval, between the Lepşa Formation (uppermost Maastrichtian) and Putna-Piatra Uscată Formation (Lower Danian), based on the Last Appearance Datum of latest Maastrichtian markers such as Pterodinium cretaceum and Palynodinium cf. grallator and on the First Appearance Datum of Danian markers such as Senoniasphaera inornata, Xenicodinium lubricum, Tectatodinium rugulatum and Eisenackia circumtabulata, and (2) a discontinuity between the two formations. The palynofacies analysis from this geological section indicates an abundance of continental organic matter (mainly opaque phytoclasts), deposited in a distal setting of the sedimentary basin. The occurtences in the palynological assemblage of some oceanic dinocyst taxa such as Impagidinium and Pterodinium suggest the same depositional environment for the geological formations analysed.

2

Dinoflagellate cysts, palynofacies and organic geochemistry of the Cretaceous-Palaeogene (K–Pg) boundary transition at the Ellès section, northeastern Tunisia

M’Hamdi A., Slimani H., Ismail-Lattrache K. B., Ali W. B.

Annales Societatis Geologorum Poloniae

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2014

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Vol. 84, No. 3

185--212

EN

A palynofacies study carried out across the Cretaceous–Palaeogene (K–Pg) boundary in the El Haria Formation at Ellès, northeastern Tunisia, revealed the presence of organic matter dominated by marine palynomorphs, mainly dinoflagellate cyst assemblages. Continental palynomorphs (sporomorphs) and amorphous organic matter (AOM) are also present in all samples. The total organic carbon (TOC) content is generally less than 0.7 wt.%. The Rock-Eval S1 parameters vary from 0.01 to 0.3 mgHC/g rock. The Rock-Eval S2 parameters vary from 0.15 to 0.57 mgHC/g rock. The hydrogen index (HI) and oxygen index (OI) values range from 61 to 214 mgHC/g TOC and 149 to 638 mgHC/g TOC, respectively. The Tmax values range from 420 to 440°C. The TOC, Rock-Eval pyrolysis and palynofacies analyses indicate that the El Haria Formation is characterized by immature organic matter type II and III and a low thermal alteration index (TAI). Also, the authors present in this paper the biostratigraphic, palaeoenvironmentl and palaeobiogeographic framework for the dinoflagellate cyst assemblages below and above the Cretaceous–Palaeogene boundary in the Ellès section.

3

Common mode conducted electromagnetic interference in inverter fed-AC motor

Miloudi H., Bendaoud A., Miloudi M., Gourbi A., Slimani H.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 12

272-275

EN

The increase of switching speed and frequency in power electronics converters has greatly improved their performances and characteristics. These advantages are accompanied with the increased level of interference, so that EMI consideration is a major task for circuit designers nowadays. In Adjustable Speed Drives (ASD), the (dv/dt) leading to conducted emissions at high frequencies which are propagated both through Common Mode (CM) and Differential Mode (DM) in the system. The circulation of high frequency parasitic currents causes several unexpected problems, such as premature deterioration of motor winding insulation and ball bearings. In this paper an inverter-fed AC motor drive is analyzed in order to predict the path of conducted emissions into Common Mode (CM) configuration, showing that both propagation modes may interfere. The equivalent circuit allows frequency-domain analysis to be performed with standard circuit simulators. The proposed circuit model allows the prediction of the main common-mode HF current components.

PL

Zwiększanie szybkości przełączania i częstotliwości w przekształtnikach energoelektronicznych pozwala na znaczącą poprawę ich parametrów. Tym korzyściom towarzyszy zwiększony poziom zakłóceń. W napędach o regulowanej szybkości ASD sygnał dv/dt powoduje zwiększoną emisję zakłóceń wysokoczęstotliwościowych w obu – w niesymetrycznych i różnicowych systemach. Obieg prądów pasożytniczych powoduje wiele nieoczekiwanych problemów, takich jak uszkodzenia izolacji uzwojeń i łożysk. W artykule przedstawiono analizę silnika zasilanego za pośrednictwem przekształtnika w celu oceny e misji zakłóceń w trybie niesymetrycznym. Schemat zastępczy pozwala na analizę w dziedzinie częstotliwości. Proponowany model pozwala na symulację i przewidywanie składowych prądów wysokoczęstotliwościowych.