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Open access

Nina Polchaninova, Galina Savchenko, Vladimir Ronkin, Aleksandr Drogvalenko and Alexandr Putchkov

Abstract

Being an essential driving factor in dry grassland ecosystems, uncontrolled fires can cause damage to isolated natural areas. We investigated a case of a small-scale mid-summer fire in an abandoned steppe pasture in northeastern Ukraine and focused on the post-fire recovery of arthropod assemblages (mainly spiders and beetles) and vegetation pattern. The living cover of vascular plants recovered in a year, while the cover of mosses and litter remained sparse for four years. The burnt site was colonised by mobile arthropods occurring in surrounding grasslands. The fire had no significant impact on arthropod diversity or abundance, but changed their assemblage structure, namely dominant complexes and trophic guild ratio. The proportion of phytophages reduced, while that of omnivores increased. The fire destroyed the variety of the arthropod assemblages created by the patchiness of vegetation cover. In the post-fire stage they were more similar to each other than at the burnt plot in the pre- and post-fire period. Spider assemblages tended to recover their pre-fire state, while beetle assemblages retained significant differences during the entire study period.

Open access

Masoud Sheidai, Tahmineh Shagholi, Maryam Keshavarzi, Fahimeh Koohdar and Habibollah Ijbari

Abstract

Tamarix L. play important role in preventing deforestation in Iran. Tamarix species exhibit wide range of morphological variation therefore, the species delimitation become difficult. This is further complicated due to similarity of morphological characters in closely related species and the occurrence of inter-specific hybridization. The present study was performed to identify Tamarix species and their potential hybrids in Semnan Province of Iran. We used ITS and ISSR and 42 morphological characters for our investigation. Molecular phylogeny of the studied species and their relationship was not in agreement with the species tree of morphological characters and with taxonomic treatment of the genus. HGT tree of ITS and morphological data obtained revealed the occurrence of inter-specific hybridization or introgression between Tamarix species.

Open access

Eleni T. Tsiobani, Maria D. Yiakoulaki and Georgios Menexes

Abstract

Seasonal variability in grasslands’ vegetation affects animals’ diet selection. We studied the seasonal changes in water buffaloes’ diet during grazing in wet grasslands in Northern Greece. We recorded each month the plant species of the vegetation and the species consumed by buffaloes. We categorized the former into three functional groups (graminoids, legumes, and forbs) and the latter into five groups (graminoids, legumes, forbs, shrubs, and trees). There were significant differences in the proportions (%) of functional groups in the vegetation and in buffaloes’ diet between seasons (χ2 test, P<0.05). Graminoids, legumes, and forbs participated in buffaloes’ diet in all seasons, while the less preferred functional groups were trees and shrubs. Buffaloes consumed ten species in all seasons but we observed the most diverse diet, in terms of plant species, in spring. The most frequently consumed species in each functional group were Cynodon dactylon (graminoids), Trifolium repens (legumes), Cichorium intybus (forbs), Rubus sp. (shrubs), and Populus sp. (trees). However, the majority of plant species in buffaloes’ diet was in very low proportions (<1%), while buffaloes did not sample at all 38 herbaceous species. Researchers need to conduct further research to understand water buffaloes’ foraging strategy regarding plants’ anti-quality characteristics.

Open access

Shlomi Voro and Itamar Lavidor

Abstract

This paper presents a new type of north finding sensor. The passive optical sensor captures images of the sky at a high frame rate and analyzes them into a polarized map of the sky with a high degree of accuracy. The sensor operates in real time, under various weather and atmospheric conditions. The sensor output shows high heading accuracy relative to the celestial true north. Based upon the NAS-14V2 astronomical method of navigation, it is possible to define the sensor global position on earth.

Open access

Tadeusz Pastusiak

Abstract

Main problem for scheduling vessel transit voyages through the Northern Sea Route is the difficulty in predicting distribution of ice boundaries in regions that cannot be overcome by individual ice classes of vessels. Scheduling of voyage is related to speed that vessels can develop and moment of time when vessels will be able to commence and complete passage safely through areas that are main obstacle and are blocking longest transit passage through the Northern Sea Route. This applies to voyages carried out by vessels navigating on their own and with support of icebreakers. Additional problem is lack of consistency of content of maps of ice cover, which can be used for vessels voyage planning through areas where ice cover occurs. Results of this research on influence of uncertain information related with time window of conditions favorable for navigation of vessels of different ice classes on schedule of theirs voyage on example of summer navigation season 2017 are presented in this work.

Open access

Sergio Magdaleno, Elisabet Lacarra, Carlos de la Casa, Manuel López, Roberto Roldán and Nuria Blanco

Abstract

The European Geostationary Navigation Overlay Service (EGNOS) augments the open public service offered by the GPS in Europe making suitable the use of GPS for safety critical applications. EGNOS is designed according to the same standard [ICAO SARPs, 2018] such as US WAAS, Japanese MSAS, GAGAN in India, SDCM in Russia and KAAS in South Korea and provides over Europe both corrections and integrity information about the GPS system. As the European SBAS, EGNOS offers three services: Open Service, Safety-of-life Service and EDAS. In general, the EGNOS Safety-of-life (SoL) Service is intended for transport applications in different domains (and currently in use by Aviation) where lives could be endangered if the performance of the navigation system is degraded below specific accuracy limits without giving notice in the specified time to alert. This requires that the relevant authority of the particular transport domain determines specific requirements for the navigation service based on the needs of that domain.

Even if the main objective of the SBAS systems is the civil aviation community, the advantages provided by this technology are very useful to users from other domains. In this sense, a new EGNOS service for maritime is currently under development with the objective to complement the existing maritime radionavigation systems (e.g. DGNSS) in the European region for enhanced accuracy and integrity information where there is no backup infrastructure or in poorly covered environments.

One of the steps needed for the development of this new EGNOS maritime service is the definition of a minimum set of recommendations for receiver manufacturers to provide them with a clear view on how to design their SBAS receivers to be compliant with the requirements defined for such a service. For that, EC, GSA, ESA and ESSP SAS have been working together since 2016 to develop guidelines for manufacturers for the implementation of SBAS in shipborne receiver. These guidelines, developed in the frame of the SBAS Working Group created in the Special Committee (SC) 104 on Differential Global Navigation Satellite Systems (DGNSS) of Radio Technical Commission for Maritime Services (RTCM), define a minimum set SBAS messages to be compliant with the International Maritime Organization (IMO) Resolution A.1046 and additionally provide a test specifications.

This paper presents a summary of these SBAS guidelines as well as the preliminary list of tests that must be fulfilled to be compliant. Additionally, a preliminary performance assessment of the EGNOS maritime service based on IMO Res. A.1046 (27) for a 24-months period during 2016, 2017 and 2018 is presented. The performance parameters are calculated using real data to show what level of performance was attained by EGNOS. The assessment was done using both EGNOS ground monitoring stations (RIMS) and fault-free receivers, based on these guidelines, fed with actual data. The performance is shown for each performance parameter defined in the IMO Res. A.1046 (27) and for navigation in Ocean Waters and coastal waters, harbour entrances and harbour approaches. The paper also includes Service Coverage maps representing where EGNOS maritime service based on IMO Res. A.1046 (27) is fulfilling the requirements.

Furthermore, GSA and ESSP, with the collaboration of The Norwegian Coastal Administration and Hurtigruten Cruises, carried out a GNSS data collection campaign of 10 days along the Norwegian coast with a trajectory through Trondheim to Kirkenes and Kirkenes to Bergen in February 2018. The aim of this data campaign was to assess EGNOS performance at user level in the maritime domain at high latitudes in Europe. The data campaign includes the navigation outside the MT27 region defined in EGNOS at that moment (70ºN). A performance assessment of EGNOS using some commercial receivers and a software receiver in line with the SBAS guidelines will be presented, showing the observed accuracy and availably results of the EGNOS solution.

Open access

Janusz Ćwiklak, Kamil Krasuski and Marek Grzegorzewski

Abstract

The article presents the results of the aircraft Cessna 172 positioning based on navigation solutions in the GPS and EGNOS (SBAS) tracking mode. The article makes a comparison of coordinate readings of the Cessna 172 in the ellipsoidal BLh frame. The verification of the coordinates of the aircraft Cessna 172 was used to assess the reliability of the GNSS satellite technique in aviation. In a research test, the navigation data were recorded by the onboard receiver Thales Mobile Mapper during an air test performed over the military aerodrome EPDE in Dęblin. Judging by the conducted investigations, it is possible to conclude that the difference in BLh coordinates of the aircraft Cessna 172 on the basis of the GPS solution and EGNOS (SBAS) solution equals, respectively: from −0.5 m to +3 m for component B; and from −2 m to +6 m for component L; from approximately −11 m to over +1 m for component h. In addition, the paper defines factors of dilution of precision PDOP, based on the GPS and EGNOS (SBAS) solutions. The average value of the PDOP coefficient for a solution in the tracking GPS mode was 2.7, whereas in the EGNOS (SBAS) tracking mode, it was equal to 2.8.

Open access

Naim Berisha, Fadil Millaku, Bekim Gashi and Vlado Matevski

Abstract

In Europe, the genus Ramonda is represented with three species: Ramonda nathaliae, Ramonda serbica and Ramonda myconi. The first two are endemic Balkan species that are distributed also in Kosovo. These species grow in limestone as well as serpentine substrates, forming chasmophytic vegetation. The species Ramonda nathaliae is found in Macedonia, Greece, Serbia and in two localities in Kosovo, in the Sharri Mountains (Luboten and Gotovushë). R. nathaliae forms the following plant associations in the serpentines of Macedonia: Asplenio­Ramondetum nathaliae and Scorzonero-Ramondetum nathaliae, and the Achilleo­Ramondetum nathaliae in limestone substrates. Ostrya carpinifolia is charateristic species in Querco pubescentis-Ostryetum carpinifoliae, Ostryo-Fagetum, Querco-Ostryetum carpinifoliae and Corylo colurnae-Ostryetum carpinifoliae. This paper presents plant communities of Ramonda nathaliae and Ostrya carpinifolia in a limestone habitat, where the proposed new plant association named Ramondo­Ostryetum carpinifoliae ass. nova. is described. This plant community belongs to the class Quercetea pubescentis, order Quercetalia pubescenti­petraeae and alliance Fraxino orni­Ostryion. It was found and described on the limestone substrate on Mt. Luboteni (at 960–982 m a.s.l.).

Open access

Jae Hee Noh, Gwang Hee Jo, Deok Won Lim, Jin Hyuk Lee, Sun Yong Lee and Sang Jeong Lee

Abstract

Research on precise positioning is being actively carried out to provide accurate position information for land transportation. The most significant problem when performing precise positioning in urban canyon is the degradation of performance due to the lack of visible satellites. Prior to open service of BDS, most of the studies on positioning were focused on using GPS/GLONASS integrated navigation system. Since BDS began open service, studies using GPS/BDS have been actively performed in the Asia-Pacific region as it became possible to acquire enough available BDS satellites. The average number of visible satellites in Korea is 9 for GPS and 14 for BDS. In this paper, we analyze the availability of precise positioning using BDS in urban canyon. To do this, we simulate the urban canyon environment by applying the mask to the azimuth and the elevation. We analyze the positioning accuracy using two simulation scenarios. From the results, it is shown that the accuracy of precise positioning in the case where the satellites in the east-west direction are blocked is lowered than that in the case where the satellites in the south-north direction are blocked for the same elevation mask angle. This result comes from the fact that the PDOP increases when the satellites are blocked in the east-west direction. Also, it can be confirmed that the GPS/BDS integrated positioning is available for the high mask angle while the GPS-only positioning is not possible continuously.

Open access

Georgi Kunev and Rossen Tzonev

Abstract

The study presents new data on the habitat dominated by the species complex of Genista lydia/G. rumelica in Bulgaria. It is based on 129 phytocoenological relevés and provides information on the chorology, ecology and floristic structure of these communities. This habitat type occupies substrates composed by different volcanic rocks. The floristic structure is very rich in species. The phytogeographical relationships with the East Mediterranean region are considerable, which is proved by the high occurrence of floristic elements with Mediterranean or sub-Mediterranean origin. The plant life-forms analysis demonstrates that the therophytes, geophytes and chamephytes prevail in their floristic structure, which is also typical for the shrub communities in this region. During the field study this vegetation type has been mapped and its total area of occupancy has been calculated. For a first time it is proposed this habitat to be divided into three habitat sub-types due to the established differences in the environmental factors. Some recommendations have been proposed on the conservation management and also complements on the habitat‘s descriptions in EUNIS habitat classification.