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Open access

Oskar Mężyk, Michał Doligalski and Ryszard Rybski

Abstract

In the work a method of latency measurement in software defined radio (SDR) is proposed and validated. The test setup uses customer grade GNSS modules as reference time sources and enables relative delay calculation between signals received directly and those bypassed through SDR platform. The method is hardware agnostic in a sense, that it does not involve any custom software or hardware modifications. Tests that compare reported carrier-to-noise ratio and positioning errors were performed to prove functionality of such system. Additionally, authors measured several gnuradio blocks with respect to their impact on total latency introduced into signal path. All tests were performed on a bladeRF low-cost RF front-end. Minimum observed latency for the signal was below 10 ms.

Open access

Viktor Onyshchenko

Abstract

The article aims to 1) describe the distribution of non-native species of vascular plants (only kenophytes, i. e. naturalized species introduced after the 15th century) in different types of forests and different biogeographical regions of Ukraine; 2) compare proportions of kenophytes in forests of different areas; 3) detect statistically significant changes in the occurrence of kenophytes over the last 80 years. The material consists of 2701 relevés sampled in 1990–2018. They were taken from Ukrainian phytocoenological publications and databases. In Ukraine, as in other European countries, the highest proportion of kenophytes (percentage of species number per relevé) is in floodplain forests (up to 9.1% in willow and poplar forests). The lowest proportion is characteristic for bog woods (0%) and most types of mountain forests. Among biogeographical regions, the highest values were found in the flatland areas of the Steppic region and the forest-steppe part of the Continental region. The most frequent species are Impatiens parviflora (predominantly in broadleaved woods, absent in relevés from the steppic biogeoregion) and Erigeron canadensis (pine woods on sand). Comparison with 1466 older relevés sampled in 1950–1989 allows us to make a conclusion that the proportion of kenophytes increased at least in one habitat type (oak-hornbeam forests).

Open access

Csaba Albert Tóth, Balázs Deák, István Nyilas, László Bertalan, Orsolya Valkó and Tibor József Novák

Abstract

Prehistoric mounds of the Great Hungarian Plain often function as refuges for relic loess steppe vegetation and their associated fauna. The Zsolca mounds are a typical example of kurgans acting as refuges, and even though they are surrounded by agricultural land, they harbour a species rich loess grassland with an area of 0.8 ha. With a detailed field survey of their geomorphology, soil, flora and fauna, we describe the most relevant attributes of the mounds regarding their maintenance as valuable grassland habitats. We recorded 104 vascular plant species, including seven species that are protected in Hungary and two species (Echium russicum and Pulsatilla grandis) listed in the IUCN Red List and the Habitats Directive. The negative effect of the surrounding cropland was detectable in a three-metre wide zone next to the mound edge, where the naturalness of the vegetation was lower, and the frequency of weeds, ruderal species and crop plants was higher than in the central zone. The ancient man-made mounds harboured dry and warm habitats on the southern slope, while the northern slopes had higher biodiversity, due to the balanced water supplies. Both microhabitats had different assemblages of ground-dwelling invertebrates.

Open access

Anatoliy Khapugin

Abstract

Paper presents a systematic global review of Acer negundo, Fraxinus pennsylvanica, Ailanthus altissima, Robinia pseudoacacia invasions focusing on the Scopus and Web of Science databases. We examined the data on papers, study areas, habitat studied, topic discussed. We hypothesized that these species were studied evenly throughout their invaded ranges and, as such, indexed by international databases. We asked whether four selected species are presented evenly in publications related to their invaded ranges, and whether both selected databases cover well a content of these papers. We found 48 papers for A. negundo, 14 – for F. pennsylvanica, 83 – for A. altissima, 96 – for R. pseudoacacia. A high percentage of the studies were conducted in Central Europe and USA (for A. altissima), while Eastern Europe, Russia, Western United States were poorly represented. Most studies were conducted in forests, and focused on impacts or distribution of aliens in invaded range, and their control and management. We encountered habitat types invaded by trees, factors influencing tree invasions, consequences of invaders’ impact on ecosystems, counteracting measures. We concluded that the use only Web of Science and Scopus is not sufficient to obtain the complete data about the invasion biology.

Open access

Balázs Deák, Csaba Albert Tóth, Ádám Bede, Iva Apostolova, Tatyana M. Bragina, Ferenc Báthori and Miklós Bán

Abstract

Eurasian steppes have an essential role in conserving biodiversity, but due to the huge habitat loss in the past centuries they are often preserved only in small refuges. Among such refuges are the ancient steppic burial mounds (the so called ‘kurgans’) which have a high cultural and historical importance and are also essential sites of nature conservation. Despite their high number (approximately half million) and conservational importance there is a huge lack of knowledge on the locality and conservational state of the kurgans in most regions of Eurasia. To fill this knowledge gap, we built a public database which allows to record and query basic information on their cultural values and factors (such as land cover type, threatening factors, cover of woody species) that might serve as a basis for their effective conservation. The database provides a transparent, public and easy-to-use source for conservation managers and landscape planners focussed on grassland conservation. In addition, it also provides background information for other associate disciplines and public agencies dealing with the protection of cultural heritage.

Open access

Jürgen Dengler, Alla Aleksanyan, Didem Ambarlı, Idoia Biurrun, Iwona Dembicz, Anna Kuzemko, Péter Török, Stephen Venn and Michael Vrahnakis

Abstract

This report summarises the activities and achievements of the Eurasian Dry Grassland Group (EDGG) from January 2018 through July 2019. During the reported period, two Eurasian Grassland Conference (EGCs) took place: the 15th EGC in Sulmona, Italy, and the 16th EGC in Graz, Austria. The 11th and 12th EDGG Field Workshops studied vegetation diversity patterns in the inner alpine valleys of Austria and Switzerland, while the 13th Field Workshop was organised in Armenia. The formerly electronic newsletter of EDGG (Bulletin of the Eurasian Dry Grassland) was transformed into a peer-reviewed international journal, called Palaearctic Grasslands, which now is attracting both scientific and photographic contributions. Furthermore, the EDGG homepage was re-constructed with a new design and content management system. The EDGG has also finalised two grassland-related Special Features during the past 1.5 years in the international journals Tuexenia and Hacquetia, and contributed with eight chapters to the book Grasslands of the World: Diversity, Management and Conservation. The vegetation-plot database GrassPlot, containing standardised multi-scale data from Palaearctic grasslands and closely connected with EDGG, has developed well, as did some other regional and national grassland-focused databases.

Open access

J. Vázquez, E. Lacarra, J. Morán, M.A. Sánchez, A. González and J. Bruzual

Abstract

EDAS (EGNOS Data Access Service) is the EGNOS internet broadcast service, which provides free of charge access to the data collected and generated by the EGNOS infrastructure. EDAS disseminates over the Internet, both in real time and via an FTP archive, the raw data of the GPS, GLONASS (no commitment on GLONASS data is provided (1)) and EGNOS GEO satellites collected by the receivers located at the EGNOS reference stations, which are mainly distributed over Europe and North Africa. The EDAS services offer several types of GNSS data in various protocols and formats, such as DGNSS corrections. This paper reports on the results of some in-field tests conducted by ESSP and Topcon Agriculture to confirm the suitability of EDAS DGNSS corrections for precision farming in Europe.

The European Commission (EC) is the owner of EGNOS system (including EDAS) and has delegated the exploitation of EGNOS to the European GNSS Agency (GSA). EDAS service provision is performed by ESSP, as EGNOS Services Provider, under contract with the GSA, the EGNOS program manager.

In the ENC 2018 article “EDAS (EGNOS Data Access Service): Differential GPS corrections performance test with state-of-the-art precision agriculture system”, ESSP and Topcon Agriculture presented the results of the first in-field test conducted in a dynamic and real-life environment in the summer of 2017. The test results indicated that the EDAS DGNSS corrections could enable a reliable pass-to-pass accuracy performance for a wide range of precision agriculture applications and become an attractive solution for cereal farms, when the farm is located in the vicinity of an EGNOS reference station. In particular, Topcon Agriculture acknowledged that the observed performance was sufficient to support the following precision agriculture applications: spraying and spreading of any crop type, tilling and harvesting of cereal.

Then, ESSP and Topcon Agriculture engaged in additional testing activities to further characterise the EDAS DGPS performance in different scenarios (i.e. at various European locations and with a variety of distances between the designated farm and the target EGNOS reference station).

In each test, multiple runs with the rover tractors have been performed over the reference patterns predefined in the Topcon guidance systems. Data recorded during the tests has been analysed in detail, looking at the key performance indicators (e.g. cross track error and pass-to-pass performance) that characterize the EDAS DGPS performance for precision agriculture applications. Different techniques for the computation of the pass-to-pass accuracy performance have been used, including a procedure to measure live in the field and a post-processing alternative. The diversity of scenarios available allows drawing conclusions on the applicability of EDAS DGPS corrections (in terms of maximum distance from the target EGNOS station) for precision agriculture and also understanding the impact of operationally relevant aspects such as the quality of the mobile internet coverage (highly variable across Europe).

The EDAS system and its architecture, the main types of data disseminated through EDAS services and the online information available to the EDAS users are introduced in this paper. In particular, the EDAS Ntrip service is described in detail, since it provides the differential corrections to the GPS and GLONASS satellites at the EGNOS reference stations in RTCM format, which are the basis for the present study.

The article also reports on the results of the latest tests, which have been performed using Topcon receivers, vehicles and auto-steering systems. In all cases, two different Topcon guidance systems on board tractors were running simultaneously to assess the EDAS DGPS positioning performance with respect to a the reference provided by a top-performing RTK-based Topcon solution.

The objective of this paper is to draw conclusions on the use of EDAS DGPS corrections as a reliable free-of-charge alternative for precision farming in Europe (especially for cereal farms), based on the available performance results from the testing campaign and the feedback from the involved precision agriculture experts.

Open access

Edwin Williams and Yan Jin

Abstract

Standard Guidance, Navigation, and Control (GN&C) systems take state data from a navigation system and create a trajectory that minimizes some a-priori determined cost function. These cost functions are typically time, money, weight, or any general physically realizable quantity. Previous work has been done to show the effectiveness of using risk as the sole objective function. However, this previous work used Poisson distributions and historical estimates to achieve this goal. In this paper we present the situation-risk assessment (SRA) method contained within the intelligent situation assessment and collision avoidance (iSC) platform. The SRA method uses data clustering, and pattern recognition to create a historically based estimate of guidance probabilities. These are then used in data driven, dynamic models to create the future probability fields of the situation. This probability, along with the other agent’s goals and objectives, are then used to create a minimum risk guidance solution in the nautical environment.

Open access

Jürgen Dengler, Stefan Widmer, Eline Staubli, Manuel Babbi, Jamyra Gehler, Daniel Hepenstrick, Ariel Bergamini, Regula Billeter, Steffen Boch, Sven Rohrer and Iwona Dembicz

Abstract

The upper Rhone valley in the Swiss canton of Valais is one of the driest and most continental of the inner-alpine valleys and harbours a rich xerothermic flora. We studied syntaxonomy and ecology of dry grasslands and their species richness patterns. In 2018 we recorded 28 vegetation plots (10 m2) and three nested-plot series of 0.0001 to 100 m2 on the south-facing slopes above the village of Ausserberg. Mean richness of all species ranged from 1.7 on 1 cm2 to 47.3 on 100 m2, with little contribution of bryophytes and lichens. The species-area relationship for total richness closely followed a power function. Modified TWINSPAN yielded a three-cluster solution, which could easily be matched with three orders of the class Festuco-Brometea: Stipo pulcherrimae-Festucetalia pallentis (xeric, rocky), Festucetalia valesiacae (xeric, non-rocky) and Brachypodietalia pinnati (meso-xeric). The subdivision of the xeric types into two orders is new for Swiss dry grasslands, where these types up to now had been joined in a single alliance Stipo-Poion within the Festucetalia valesiacae.

Open access

Orsolya Valkó, Rocco Labadessa, Salza Palpurina, Sabina Burrascano, Atushi Ushimaru and Stephen Venn

Abstract

Palaearctic grasslands are diverse and dynamic ecosystems that are in the focus of ecology, conservation biology and agronomy. This special issue is dedicated to the biodiversity and conservation issues of Palaearctic grasslands and was initiated by the Eurasian Dry Grassland Group members attending the 14th Eurasian Dry Grassland Conference (EDGC) at Sulmona, Italy in 2018. The papers in this special issue cover a wide range of grassland ecosystems from mountain dry grasslands to lowland loess grasslands, feathergrass steppes and wet grasslands, and focus on the biodiversity values and conservation issues of Palaearctic grasslands. We believe that this compilation will contribute to a better understanding of the ecology of grasslands and support their more effective conservation.