Communication via satellite begins when the satellite is positioned in the desired orbital position. Ground stations can communicate with LEO (Low Earth Orbiting) satellites only when the satellite is in their visibility region. The duration of the visibility and so the communication duration varies for each satellite pass at the ground station, specifically for LEO satellites which do move too...

In this paper we present a model to study the end-to-end delay performance of a satellite-ATM network. We describe a satellite-ATM network architecture. The architecture presents a trade-off between the on-board switching/processing features and the complexity of the satellite communication systems. The end-to-end delay of a connection passing through a satellite constellation consists of the t...

| We propose a new framework for the link assignment (i.e., topological design) problem that arises from the use of inter-satellite links (ISL's) in Low-Earth Orbit (LEO) satellite networks. In the proposed framework, we model a LEO satellite network as a Finite State Automaton (FSA) where each state corresponds to an equal-length interval in the system period of the LEO satellite network. This...

Many (mathematical) problems, such as Cantor’s theorem, can be expressed very elegantly in higher-order logic, but lead to an exhaustive and un-intuitive formulation when coded in first-order logic. Thus, despite the difficulty of higher-order automated theorem proving, which has to deal with problems like the undecidability of higher-order unification (HOU) and the need for primitive substitut...

Whether a dwarf spheroidal galaxy is in equilibrium or being tidally disrupted by the Milky Way is an important question for the study of its dark matter content and distribution. This question is investigated using 328 recent observations from the dwarf spheroidal Leo I. For Leo I, tidal disruption is detected, at least for stars sufficiently far from the center, but the effect appears to be q...

four in vitro experiments (exp.) were conducted to evaluate lavender essential oil (leo) effects at 0 (control), 250 (low dose), 500 (medium dose), 750 and 1000 µl per l(high doses) of incubation medium on rumen gas production kinetics (exp.1), ruminal digestibility and fermentation (exp.2), methane production (exp.3) and rumen acidosis (exp.4). the asymptote of gas production (a) increased qua...

LEO satellite has an important role in global communication system. They have advantages like low power requirement and lower end-to-end delay, efficient frequency spectrum utilization between satellites and spotbeams over MEO and GEO satellites. So in future they can be used as a replacement of modern terrestrial wireless networks. There are a lot of handover techniques for LEO satellites like...

Radial-velocity measurements and sine-curve fits to the orbital radial velocity variations are presented for ten close binary systems: OO Aql, CC Com, V345 Gem, XY Leo, AM Leo, V1010 Oph, V2612 Oph, XX Sex, W UMa, and XY UMa. Most of these binaries have been observed spectroscopically before, but our data are of higher quality and consistency than in the previous studies. While most of the stud...

We compare the performances of two diierent routing schemes for LEO satellite networks through simulation. The rst one is a dynamic routing scheme based on the shortest-path algorithm. Its routing table is updated according to cost estimation based on link status information that is broadcasted periodically. The second one is an optimal routing scheme proposed by the authors of this paper, wher...