Multipath Study On The Airport Surface

Audrey Guilloton and Jean-Pierre Arethens, Thales Avionics, Anne-Christine Escher and Christophe Macabiau, Enac, Damien Koenig, Gipsa-Lab

Airport Navigation will require more stringent localization performance requirements than in-flight navigation. GNSS signals (Global Navigation Satellites Systems) can be envisaged to elaborate the aircraft estimate position on the airport surface. To improve the performance of localization on the airport, the errors on GNSS signals particular to the airport environment must be characterized. Most of these errors are well known such as ionosphere error, troposphere error, etc, and do not depend on the airport environment. But to achieve the expected sub-metric performance, it is necessary to better model multipath error for which a model already exists but is valid for operations from en-route down to CAT I only. In this paper, an analysis of real GPS measurements (using code pseudorange measurement, carrier phase measurement, Doppler measurement and the estimate C/N0 ratio measurement) during taxiing operation on the airport surface is conducted. The goal of this paper is to evaluate when multipath occurs and to compare the multipath model (elaborated from the standard deviation of the measurement errors due to multipath) based on those collected measurements in the airport with different models proposed in the literature (not necessary proposed for airport navigation).

Total probability theorem, Bayes’s rule and study of ships damage stability : a  pedagogical journey in the heart of probabilistic rules Solas 2009


François-Xavier Nettersheim, Capitaine de 1ère classe de la navigation maritime

Subdivision and damage stability of ships are governed by two sets of design and building rules: deterministic rules and probabilistic rules. The principles of these rules are completely different. The probabilistic rules known as “Solas 2009” are quite complex and rather difficult to interpret. After a summary of the “Solas 2009” regulatory provisions, this article is developing a pedagogical approach allowing the understanding of their foundation and in deep significance.


Renewal of Shom tide products : an adjustement to the needs and modern  communication systems


Nicolas Weber


Since 1839, date of the publication of the first tide table, the French hydrographic and oceanographic office delivers various tide information in many forms (tide tables, software, books…). This article describes the work engaged for updating tide products since 2006. This work first aims to meet the new needs of users of the sea, individuals, professionals or personnel belonging to institutional organizations. This work takes also into account new technologies and new practices (web, mobile telephony, data processing, computers…).

Walking with coffee: Why does it spill?


H. C. Mayer and R. Krechetnikov, Department of Mechanical Engineering, University of California, USA

In our busy lives, almost all of us have to walk with a cup of coffee. While often we spill the drink, this familiar phenomenon has never been explored systematically. Here we report on the results of an experimental study of the conditions under which coffee spills for various walking speeds and initial liquid levels in the cup. These observations are analyzed from the dynamical systems and fluid mechanics viewpoints as well as with the help of a model developed here. Particularities of the common cup sizes, the coffee properties, and the biomechanics of walking proved to be responsible for the spilling phenomenon. The studied problem represents an example of the interplay between the complex motion of a cup, due to the biomechanics of a walking individual, and the low-viscosity-liquid dynamics in it.

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