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Wyświetlanie 1-5 z 5
Tytuł:
Acanthodians from the Lower Devonian (Emsian) ‘Placoderm Sandstone’, Holy Cross Mountains, Poland
Autorzy:
Burrow, C. J.
Szrek, P.
Powiązania:
https://bibliotekanauki.pl/articles/139217.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Acanthodii
Machaeracanthus
Striacanthus
Onchus
Emsian
Lower Devonian
Polska
fałdopłetwe
akantody
ems
dewon dolny
Polska
Opis:
The Lower Devonian ‘Placoderm Sandstone’ in the Holy Cross Mountains (HCM) is filled with abundant impressions of disarticulated vertebrate remains. The only acanthodian macroremains named to date are fin spines of Machaeracanthus polonicus Gürich. Fin spine impressions in slabs from the Winna Formation (Emsian) at Podłazie Hill (near Daleszyce) in the southern HCM, and also the Barcza Formation (?Lochkovian) at Barcza Quarry, Miedziana Góra Conglomerate (?Lochkovian), Gruchawka, and Zagórze Formation (middle–upper Emsian) at Bukowa Mountain in the northern HCM, reposited in the University of Warsaw, Polish Geological Institute-National Research Institute, Warsaw, and Natural History Museum, London collections, have been cast and studied in order to better document this poorly known taxon. As noted in other Machaeracanthus species, we have found that M. polonicus has two different morphotypes of spines, which abut lengthwise to form a pair of spines. Our investigations show that the fin spine assemblage includes Onchus overathensis as well as M. polonicus, and probably another undetermined acanthodian. The affinities of O. overathensis are reassessed. It is here considered to be a diplacanthiform, and reassigned to the genus Striacanthus, as S. overathensis. Acanthodian scapulocoracoids have also been identified, as well as tightly spiralled toothwhorls which could be from an acanthodian.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 307-320
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Storm origin of bone-bearing beds in the Lower Devonian placoderm sandstone from Podłazie Hill (Holy Cross Mountains, central Poland)
Autorzy:
Szrek, P.
Niedźwiedzki, G.
Dec, M.
Powiązania:
https://bibliotekanauki.pl/articles/2060466.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Placoderm Sandstone
Lower Devonian
Emsian
Holy Cross Mountains
Polska
Opis:
The placoderm sandstone (Emsian, Holy Cross Mountains) exposed in the abandoned quarry at Podłazie Hill was revisited and excavated during fieldwork conducted in 2011-2013. Bone-bearing breccias were identified for the first time at this site and subjected to taphonomic analysis. Vertebrate remains are dominated by heterostracans, while true placoderms compose less than 20% of the total vertebrate assemblage. The high degree of fragmentation of the bones and low degree of abrasion indicate that the remains were reworked and transported before final burial. This is consistent with the mixed character of the bone accumulations, which comprise both open-shelf forms (acanthodians, chondrichthyans) as well as those related to marginal-marine environments (placoderms and sarcopterygians). The bone-bearing succession has been subdivided into five depositional facies attributed to a coastal lagoon influenced by stormy, possibly tidal conditions. The occurrence of the invertebrate trace fossil Ilmenichnus sp. accompanied by Lockeia and Monomorphichnus supports this interpretation.
Źródło:
Geological Quarterly; 2014, 58, 4; 795--806
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New cranial material of the acanthothoracid placoderm Palaeacanthaspis vasta from the Lower Devonian of Podolia—phylogenetic and taxonomic significance
Autorzy:
Dupret, V.
Szaniawski, H.
Dec, M.
Szrek, P.
Powiązania:
https://bibliotekanauki.pl/articles/2082331.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Placodermi
Acanthothoraci
neurocranium
Lochkovian
Devonian
Podolia
Ukraine
Opis:
The Early Devonian vertebrates of Podolia in Ukraine are well known thanks to the material of the basal arthrodire placoderm genus Kujdanowiaspis, originally mentioned by Brotzen in 1934. The anatomical fame of Kujdanowiaspis brought by Erik Stensiö almost eclipsed the presence of the acanthothoracid placoderm Palaeacanthapsis vasta in the underlying beds, with the original material of P. vasta being less well preserved and abundant than that of Kujdanowiaspis. Here we describe a newly discovered specimen of the acanthothoracid P. vasta from the Lochkovian of Podolia (Ukraine). The specimen, although incomplete, is very well preserved in three dimensions and allows a thorough description of its external morphology, which is compared to that of Romundina stellina and other well-known Acanthothoraci. A phylogenetic analysis is performed and the acanthothoracid nature of Palaeacanthaspis is confirmed. However, the position of Palaeacanthaspis within the Acanthothoraci remains uncertain, and its resemblance with Romundina could be due to either synapomorphies or symplesiomorphies. Similarities and differences between the two forms are exposed, and lead to the lack of synonymy at the specific level. Generic synonymy is also questioned for the first time but remains equivocal.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 337-347
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Idea of wheel-legged robot and its control system design
Autorzy:
Szrek, J.
Wojtowicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/199933.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wheel-legged robot
control system design
Opis:
The wheel-legged robot is a vehicle with many degrees of freedom. Thanks to its peculiar design, depending on the need, the vehicle will use one of its ways of moving: travelling on wheels or walking (in special situations), which enhances its locomotive properties. The paper presents the robot’s kinematic wheel suspension system, general operation strategy and control system. The application responsible for robot control and data visualization is described. Finally, selected tests of the algorithms, carried out on the robot prototype, are presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 1; 43-50
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Type synthesis, modelling and analysis of the manipulator for wheel-legged robot
Autorzy:
Szrek, J.
Muraszkowski, A.
Sperzyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/386987.pdf
Data publikacji:
2016
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
mobile manipulator
multibody dynamics analysis
wheel-legged platform
robot mobilny
manipulator mobilny
dynamika układów wieloczłonowych
Opis:
The aim of this article is to present the concept of wheel-legged mobile manipulator, which is a combination of mobile platform with specially selected suspension system and a manipulator. First, a literature review was performed and own solution proposed. The kinematic structure of manipulator, selected simulation results, physical model and the concept of the control system has been presented. Geometry synthesis was used to design basic dimension. Structural synthesis was performed according to the intermediate chain method. Simulations were performed using the multibody dynamics simulation software. New approach in the field of the mobile manipulators was presented as a result.
Źródło:
Acta Mechanica et Automatica; 2016, 10, 2; 87-91
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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