Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Håkansson, M." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Low bandwidth network-RTK correction diissemination for high accuracy maritime navigation
Autorzy:
Alissa, S.
Håkansson, M.
Henkel, P.
Mittmann, U.
Hüffmeier, J.
Rylander, R.
Powiązania:
https://bibliotekanauki.pl/articles/1841552.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
real time kinematic
high accuracy maritime navigation
network-RTK
Global Navigation Satellite System
VHF data exchange system
GNSS receiver
virtual reference station
physical reference stations
Opis:
More than half of the incidents reported to EMSA relate to nautical events such as collision, groundings and contacts. Knowledge of accurate and high-integrity positioning is therefore not only a need for future automated shipping but a base for today’s safe navigation. Examples on accidents include Ever Given in the Suez Canal and HNoMS Helge Ingstad in Norway. A Network-RTK (NRTK) service can be used as an augmentation technique to improve performance of shipborne GNSS receivers for future positioning of manned and unmanned vessels in restricted areas, such as port areas, fairways, and inland water ways. NRTK service providers generate RTK corrections based on the observations of networks of GNSS reference stations which enables the users to determine their position with centimeter accuracy in real-time using a shipborne GNSS receiver. Selection of appropriate communication channels for dissemination of NRTK corrections data is the key to a secure positioning (localization) service. In PrePare-Ships project, the modern maritime communication system VDES (VHF Data Exchange System) is proposed to distribute SWEPOS (NRTK in Sweden) correction data to shipborne positioning modules. VDES is a very reliable technique and it is compatible with most onboard functionalities. In order to minimize the impact on the overall VDES data capacity in a local area, NRTK correction data shall only occupy a single VDES slot with a net capacity of 650 bytes. Update rates may vary but are preferably at 1Hz. However, NRTK correction data size changes instantly, depending on the number of visible GNSS satellites, and the data rate can therefore sometimes reach in excess of 1000 byte/s. In this study, a smart technique is proposed to reduce size of NRTK correction data to instantly adapt with the VDES requirements by choosing a combination of specific signals, satellites or even constellations such that the data rate is not more than 650 byte/s, and at the same time it achieves optimal positioning performance with the accuracy required by the PrePare-Ships project application.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2021, 15, 1; 171-179
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dańskie amonity - obecny stan wiedzy i perspektywy badań
Danian ammonites - The present state of knowledge and perspectives for future research
Autorzy:
Machalski, M.
Jagt, J.W.M.
Heinberg, C.
Landman, N.H.
Hakansson, E.
Powiązania:
https://bibliotekanauki.pl/articles/2074714.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
masa wymarła
amonity
odsłonięcia K-Pg
relikt
odrodzenie
uderzenie
anomalia irydowa
Maastricht
Dania
Holandia
New Jersey
ammonites
K-Pg boundary
mass extinctions
survival
recovery
impact
iridium anomaly
Danian
Denmark
Opis:
To date, the strongest arguments for ammonite survival into the Danian (earliest Paleogene) are based on material from the lower Danian Cerithium Limestone at Stevns Klint (Denmark), where ammonites occur above a clay layer with impact products at its base, the latter defining the Cretaceous-Paleogene (K-Pg) boundary. The best-preserved specimen is filled with Danian sediment rather than with Maastrichtian chalk, which would be expected had this been reworked material. Arguments for ammonite survival into the Danian have also been provided by specimens from the sporomorph and calcareous nannoplankton-dated lowermost Danian strata of Meerssen Member unit IVf-7, the Netherlands. Their good preservation indicates that they were not subject to any significant transport or redeposition. However, there are no unequivocal impact-related signatures in unit IVf-7, except for rare shocked quartz grains, recorded from burrows at its base. Sections in the Manasquan Basin, New Jersey, USA, provide equivocal data as far as the problem of ammonite survival into the Danian is concerned. At the top of the Tinton Formation there is a Pinna layer replete with fossils, inclusive of ammonites. Their exquisite preservation and occurrence in monospecific clusters rule out redeposition. The Pinna layer contains exclusively late Maastrichtian microfossils. However, a clear iridium anomaly has been noted at its base. Either the New Jersey ammonites survived the K-Pg event for a short time or the iridium is not in situ due to post-depositional repositioning by percolating water. Planned work is to focus on: 1) a detailed centimetre by centimetre sampling of some Cerithium Limestone basins in Denmark in search of additional ammonite material, 2) palaeontological and taphonomic analysis of ammonites and search for impact signatures in unit IVf-7 in the Netherlands, and 3) geochemical study of the iridium anomaly in New Jersey in order to determine whether its position in respect to the ammonite-bed is original or secondary.
Źródło:
Przegląd Geologiczny; 2009, 57, 6; 486-493
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies