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Wyszukujesz frazę "Sokołowski, R. J." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt
Autorzy:
Woronko, B.
Zieliński, P.
Sokołowski, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/94408.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
fluvial to aeolian succession
aeolization of quartz sand grains
periglacial conditions
extraglacial zone
eolizacja ziaren piasku
piasek kwarcowy
warunki peryglacjalne
Opis:
We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.
Źródło:
Geologos; 2015, 21, 2; 89-103
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
River response to climate and sea level changes during the Late Saalian/Early Eemian in northern Poland – a case study of meandering river deposits in the Chłapowo cliff section
Autorzy:
Moskalewicz, D.
Sokołowski, R. J.
Fedorowicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/94416.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
point-bar succession
meandering fluvial system
Quaternary geology
fluvial sedimentology
Eemian Sea
następstwo odsypu meandrowego
meandrujący system rzeczny
geologia czwartorzędu
sedymentologia rzeczna
morze eemskie
Opis:
Fluvial sediments in the Chłapowo cliff section were studied in order to reconstruct their palaeoflow conditions and stratigraphical position. Lithofacies, textural and palaeohydraulic analyses as well as luminescence dating were performed so as to achieve the aim of study. Sedimentary successions were identified as a record of point bar cycles. The fluvial environment probably functioned during the latest Saalian, shortly after the retreat of the Scandinavian Ice Sheet. Discharge outflow was directed to the northwest. The river used the older fluvioglacial valley and probably was directly connected to the Eem Sea. Good preservation and strong aggradation of point-bar cycles were related to a rapid relative base level rise. The meandering river sediments recognised showed responses to climate and sea level changes as illustrated by stratigraphical, morphological and sedimentological features of the strata described. The present study also revealed several insights into proper interpretation of meandering fluvial successions, in which the most important were: specific lithofacies assemblage of GSt (St, Sp) → Sl → SFrc → Fm (SFr) and related architectural elements: channel/sandy bedforms CH/SB → lateral accretion deposits LA → floodplain fines with crevasse splays FF (CS); upward-fining grain size and decreasing content of denser heavy minerals; estimated low-energy flow regime with a mean depth of 1.6–3.3 m, a Froude number of 0.2–0.4 and a sinuosity of 1.5.
Źródło:
Geologos; 2016, 22, 1; 1-14
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Depositional conditions on an alluvial fan at the turn of the Weichselian to the Holocene – a case study in the Żmigród Basin, southwest Poland
Autorzy:
Zieliński, P.
Sokołowski, R. J.
Fedorowicz, S.
Woronko, B.
Hołub, B.
Jankowski, M.
Kuc, M.
Tracz, M.
Powiązania:
https://bibliotekanauki.pl/articles/94513.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
climate change
periglacial environment
fluvial processes
aeolian processes
luminescence dating
zmiana klimatu
środowisko peryglacjalne
procesy fluwialne
procesy eoliczne
datowanie luminescencyjne
Opis:
Presented are the results of research into the fluvio-aeolian sedimentary succession at the site of Postolin in the Żmigród Basin, southwest Poland. Based on lithofacies analysis, textural analysis, Thermoluminescence and Infrared-Optical Stimulated Luminescence dating and GIS analysis, three lithofacies units were recognised and their stratigraphic succession identified: 1) the lower unit was deposited during the Pleni-Weichselian within a sand-bed braided river functioning under permafrost conditions within the central part of the alluvial fan; 2) the middle unit is the result of aeolian deposition and fluvial redeposition on the surface of the fan during long-term permafrost and progressive decrease of humidity of the climate at the turn of the Pleni to the Late Weichselian; 3) the upper unit accumulated following the development of longitudinal dunes at the turn of the Late Weichselian to the Holocene; the development of dunes was interrupted twice by the form being stabilised by vegetation and soil development.
Źródło:
Geologos; 2016, 22, 2; 105-120
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural frequencies and modes shapes of two rigid bladed discs on the shaft
Autorzy:
Rządkowski, R.
Sokołowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1955709.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
natural frequencies
bladed disc-shaft
Opis:
The dynamic behavior of a rotor consisting of two bladed discs on a solid shaft is considered. The effect of shaft flexibility on the dynamic characteristics of the bladed discs and the coupling effects between the shaft and bladed disc modes are investigated. Results presented for various cases with differing blade flexibility show clearly the coupling effects in a bladed disc-shaft system. Interference diagrams are developed, from which the dynamic behavior of a system can be predicted for differing flexibility relationships between the solid shafts and the bladed discs. In this study, the global rotating mode shapes of flexible bladed disc-shaft assemblies have been calculated. Rotational effects such as centrifugal stiffening have been accounted for, and all the possible couplings between the flexible parts have been allowed. Gyroscopic effects have been included in the shaft with two discs. Calculated natural frequencies obtained from the blade, shaft, bladed disc and shaft with two discs have been checked to determine resonance conditions and coupling effects. The calculations have shown the influence of the shaft on the natural frequencies of the bladed discs up to one nodal diameter frequencies. The torsional frequency of the shaft with two discs is coupled with the zero nodal diameter modes of the single bladed discs. The bending modes of the shaft are coupled with one nodal diameter modes of the bladed discs. It is shown that including the shaft in the bladed discs model is important from a designer's point of view and can change the spectrum of frequencies considerably.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 1; 51-69
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequencies and modes of rotating flexible shrouded bladed discs-shaft assemblies
Autorzy:
Sokołowski, J.
Rządkowski, R.
Kwapisz, L.
Powiązania:
https://bibliotekanauki.pl/articles/1954654.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
blades
discs
shaft
free vibration
Opis:
It is now increasingly necessary to predict accurately, at the design stage and without excessive computing costs, the dynamic behaviour of rotating parts of turbomachines, so that resonant conditions at operating speeds are avoided. In this study, global rotating mode shapes of flexible shrouded bladed disc-shaft assemblies are calculated. The rotating modes have been calculated by using a finite element cyclic symmetry approach. Rotational effects, such as centrifugal stiffening have been accounted for, and all the possible couplings between the flexible parts have been allowed. Gyroscopic effects have been neglected. The numerical results have been compared with the experimental. The calculations show the influence of shaft flexibility on the natural frequencies of shrouded bladed discs up to four nodal diameters for the two first frequencies series.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 2; 215-231
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Marine ecogeology in semi-closed basin: case study on a threat of geogenic pollution of the southern Baltic Sea (Polish Exclusive Economic Zone)
Autorzy:
Sokołowski, A.
Sokołowski, J.
Pokorski, J.
Jaworowski, K.
Wagner, R.
Modliski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2059068.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Źródło:
Geological Quarterly; 2010, 54, 2; 267-288
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hybrid heptafocal intraocular lenses
Autorzy:
Sokolowski, M
Pniewski, J.
Brygola, R
Kowalczyk-Hernandez, M
Powiązania:
https://bibliotekanauki.pl/articles/174719.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
diffractive lens
hybrid lens
multifocal intraocular lens
Opis:
In this paper, hybrid diffractive-refractive multifocal intraocular lenses are proposed, which are intended to provide good visual acuity over a discrete spectrum of object distances most often encountered by patients. The proposed hybrid lenses have seven foci. It is shown that by the appropriate selection of modulation depth of a sinusoidal phase diffractive profile and the period of the sinusoid, sharp vision can be achieved for a set of distances such as 24, 29, 37, 49, 73, 145 cm, and infinity. Theoretical axial and lateral visual point spread functions are computed. An accommodative amplitude equivalent of the eye implanted with a multifocal intraocular lens is introduced and calculated for the proposed heptafocal intraocular lenses.
Źródło:
Optica Applicata; 2015, 45, 3; 285-298
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topological derivatives for semilinear elliptic equations
Autorzy:
Iguernane, M.
Nazarov, S. A.
Roche, J. R.
Sokolowski, J.
Szulc, K.
Powiązania:
https://bibliotekanauki.pl/articles/907655.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
optymalizacja kształtu
pochodna topologiczna
nierówność wariacyjna
analiza asymptotyczna
shape optimization
topological derivative
level set method
variational inequality
asymptotic analysis
Opis:
The form of topological derivatives for an integral shape functional is derived for a class of semilinear elliptic equations. The convergence of finite element approximation for the topological derivatives is shown and the error estimates in the L [...] norm are obtained. The results of numerical experiments which confirm the theoretical convergence rate are presented.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 2; 191-205
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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