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A new tool for analysing antenna radiation patterns is proposed in this article. This tool consists in applying a spherical wavelet transform to the radiation which is assumed to be known on a regular spherical-coordinates grid. This is an alternative solution to usual plane-waves or spherical harmonic expansions. The interest of using wavelets is to obtain a better analysis in terms of localization in position and/or direction. The direct link between spherical wavelets and spherical harmonics is also highlighted. The properties of this tool are illustrated by means of numerical experiments performed on two typical antennas, a canonical aperture and a pyramidal horn.

Anomalous tropospheric refraction causes performance of naval radar systems to deviate from the normal. The main goal of this thesis is to develop a refractivity inversion technique to predict the anomalies in radar coverage accurately in real-time. In this study, the altitude-dependent refractivity is predicted from phaseless radio wave measurements taken in bistatic configuration. We are interested in exploring the inversion techniques which are efficient in high-dimensional realistic scenarios during maritime operations and which can maintain accuracy with minimum possible need for case-specific a priori information. The long-term goal is to transfer the de- veloped...

This study investigates the importance of choosing the first (respectively last) hop to access (respectively to exit) a Low Earth Orbit (LEO) satellite constellation, which is of upmost importance for the LEO routing performance. Usually, basic routing strategies connect a ground station to its nearest satellite, and this strategy does not always lead to the optimal routing path. We propose to select this first/last satellites within a subset of knearest satellites. After performing routing simulations over one of the next-generation satellite constellations, preliminary results show that this in/out hop selection strategy leads to a better link capacity usage and a lower...

We present a novel landing site selector capable of selecting suitable landing sites (airport and off-airport) for emergency landings. In a first step, information from several databases which includes, for instance, elevation data, is gathered by our system. Then, this information is processed in order to create a list of potential landing sites ranked according to several factors, such as the characteristics of the runway, the type of emergency or the current weather. A generic scenario and case studies have been defined in order to test the landing site selector, ultimately leading to a series of trajectories-generated with an emergency trajectory generator presented...

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Even if enhancing safety remains a key challenge in civil aviation, safety research has mainly focussed on front line operators, senior managers and safety managers. This paper aims to shed light on the middle managers, more specifically on the overall context that influences their contribution to safety in their daily operations, and the challenges they face. Over a two-year period, extensive field research was undertaken involving six sector organisations, and overall forty-three middle managers. Interviews were conducted to capture the participants’ views and experiences in embedding safety-related aspects in their daily activities and actions. A data-driven approach...