On the ecology of Tellina fabula Gmelin (Bivalvia) in the German Bight

Reproduction, growth, mortality, and variations in abundacne and biomass of Tellina fabula (Bivalvia) in der German Bight in 1975/76. An inshore and an offshore population of the bivalve T. fabula were investigated on sandy sediment in the German Bight from July 1975, to September 1976. A growth experiment of one year and studies of the behaviour were conducted at the same time in the laboratory. T. fabula is a deposit feeder as well as a supsension feeder; there is evidence that it changes its feeding behaviour with age and season

Oscillations of macrobenthos in shallow waters of the Peruvian central coast induced by EI Niño 1982-83

Macrozoobenthos was sampled at 15 m (January 1982–October 1984) and 34 m depth (September 1981–September 1984) in the Bay of Ancón, north of Lima. Fluctuations in density, biomass, species composition and diversity of the fauna as well as oscillations in the density of several dominant species were studied in relation to temperature, salinity and dissolved oxygen. El Niño (EN) 1982–83 induced marked positive effects at both depths. Some of these changes prevailed in 1984 due to the increase of oxygen close to the seafloor and the persistence of higher O2 values during and after the phenomenon. The number of species at 15 m, which before EN fluctuated between 3 and 17, increased to \u3e26 (max. 45) during EN and in the months following the event. Biomass, before EN always \u3c1 g, reached 18.4 g AFDW per m2 in December 1982. Density, normally \u3c4000 per m2, increased to 1724, and diversity nearly doubled and remained high until September 1984. The number of species at 34 m (≥5 before EN) fluctuated between 15 and 24 from December 1982 to February 1983 and returned to ≥5 by June 1984. Biomass reached 6.9 g AFDW per m2 in December 1982. Density, normally \u3c425 per m2, increased to 13550, and diversity at this depth nearly tripled in February 1983

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Validating Avionics Conceptual Architectures with Executable Specifications

Current avionics systems specifications, developed after conceptual design, have a high degree of uncertainty. Since specifications are not sufficiently validated in the early development process and no executable specification exists at aircraft level, system designers cannot evaluate the impact of their design decisions at aircraft or aircraft application level. At the end of the development process of complex systems, e. g. aircraft, an average of about 65 per cent of all specifications have to be changed because they are incorrect, incomplete or too vaguely described. In this paper, a model-based design methodology together with a virtual test environment is described that makes complex high level system specifications executable and testable during the very early levels of system design. An aircraft communication system and its system context is developed to demonstrate the proposed early validation methodology. Executable specifications for early conceptual system architectures enable system designers to couple functions, architecture elements, resources and performance parameters, often called non-functional parameters. An integrated executable specification at Early Conceptual Architecture Level is developed and used to determine the impact of different system architecture decisions on system behavior and overall performance

Estimation of optical flow for large displacements

In this paper we present a new method to estimate optical flow for large displacements. It is based on prediction of global flow field parameters, performs better than multiresolution estimation methods and has been verified using standard test sequences as well as real-world data. Global flow field parameters can be estimated from optical flow measurements in all flow regions. They can then be used to predict the flow in optical flow regions of the next frame. This technique reduces the complexity in comparison to hierarchy-based methods, while the flow field parameters can also be used to compensate optical flow produced by egomotion

Comparision of the Probability of Visibility of New Planned Mobile Satellite Systems (M-Star, Celestri, SkyBridge)

In the years 1996 and 1997 some new mobile satellite systems for communication services with high data rates have been proposed. The most important systems are M-Star, Celestri, and SkyBridge. In this paper the probability of visibility is presented for these new planned mobile satellite systems for low earth orbits (LEO). The performance of a satellite system is primarily dependent on the probability of visibility and the elevation limit. The probability of visibility should be 100% over a wide range of elevation limit in order to provide continual service. This papers presents the probability of visibility and the elevation limit for different latitudes and compares the three systems. Additionally, the three systems will be compared with the changed Teledesic systems, which constellation was reduced to 288 satellites in the year 1997. I.INTRODUCTION In the last years a number of mobile satellite systems for low earth orbits (LEO) and for medium earth orbits (MEO) have been proposed. ..

Link Strategy for the Mobile Satellite System Iridium

This paper developes crosslink routing strategies for the Mobile Satellite System Iridium [1,3,6,8]. Motorola&apos;s Iridium satellite constellation, based on the orbit design of Adams and Rider [2] is to provide mobile satellite service for hand-held personal telephones. The Iridium system will have 66 satellites in 6 orbital planes at an altitude of h = 780 km and a minimum elevation angle of q = 8.2 degrees for an optimal satellite distribution around the globe. It will be a system with direct connections between satellites (Intersatellite Links ISLs). These connections can be established with Intra-Orbit ISLs and with Inter-Orbit ISLs. The problem of routing messages through the satellite network is complicated by the time-varying satellite system geometry. The relative motion between the synchronized orbital planes is relatively small. However, orbital planes 1 and 6 are counterrotating and have large relative motion. Different Inter-Orbit ISL routing strategies are needed for these tw..