Automatic target recognition using passive bistatic radar signals

Doctoral thesis (2013)

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e ... [more ▼]

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e. airplanes that do not provide information when interrogated, in the framework of passive bistatic radar systems. Passive bistatic radar systems use one or more illuminators of opportunity (already present in the field), with frequencies up to 1 GHz for the transmitter part of the systems considered here, and one or more receivers, deployed by the persons managing the system, and not co-located with the transmitters. The sole source of information are the signal scattered on the airplane and the direct-path signal that are collected by the receiver, some basic knowledge about the transmitter, and the geometrical bistatic radar configuration. The three distinct ATR systems that we built respectively use the radar images, the bistatic complex radar cross-section (BS-RCS), and the bistatic radar cross-section (BS- RCS) of the targets. We use data acquired either on scale models of airplanes placed in an anechoic, electromagnetic chamber or on real-size airplanes using a bistatic testbed consisting of a VOR transmitter and a software-defined radio (SDR) receiver, located near Orly airport, France. We describe the radar phenomenology pertinent for the problem at hand, as well as the mathematical underpinnings of the derivation of the bistatic RCS values and of the construction of the radar images. For the classification of the observed targets into pre-defined classes, we use either extremely randomized trees or subspace methods. A key feature of our approach is that we break the recognition problem into a set of sub-problems by decomposing the parameter space, which consists of the frequency, the polarization, the aspect angle, and the bistatic angle, into regions. We build one recognizer for each region. We first validate the extra-trees method on the radar images of the MSTAR dataset, featuring ground vehicles. We then test the method on the images of the airplanes constructed from data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.99. We test the subspace methods on the BS-CRCS and on the BS-RCS of the airplanes extracted from the data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.98, with variations according to the frequency band, the polarization, the sector of aspect angle, the sector of bistatic angle, and the number of (Tx,Rx) pairs used. The ATR system deployed in the field gives a probability of correct recognition of 0.82, with variations according to the sector of aspect angle and the sector of bistatic angle. [less ▲]

Surface mass balance model intercomparison for the Greenland ice sheet

in Cryosphere (The) (2013), 7

A number of high resolution reconstructions of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) have been produced using global re-analyses data extending back to 1958. These ... [more ▼]

A number of high resolution reconstructions of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) have been produced using global re-analyses data extending back to 1958. These reconstructions have been used in a variety of applications but little is known about their consistency with each other and the impact of the downscaling method on the result. Here, we compare four reconstructions for the period 1960–2008 to assess the consistency in regional, seasonal and integrated SMB components. Total SMB estimates for the GrIS are in agreement within 34% of the four model average when a common ice sheet mask is used. When models' native land/ice/sea masks are used this spread increases to 57%. Variation in the spread of components of SMB from their mean: runoff 42% (29% native masks), precipitation 20% (24% native masks), melt 38% (74% native masks), refreeze 83% (142% native masks) show, with the exception of refreeze, a similar level of agreement once a common mask is used. Previously noted differences in the models' estimates are partially explained by ice sheet mask differences. Regionally there is less agreement, suggesting spatially compensating errors improve the integrated estimates. Modelled SMB estimates are compared with in situ observations from the accumulation and ablation areas. Agreement is higher in the accumulation area than the ablation area suggesting relatively high uncertainty in the estimation of ablation processes. Since the mid-1990s each model estimates a decreasing annual SMB. A similar period of decreasing SMB is also estimated for the period 1960–1972. The earlier decrease is due to reduced precipitation with runoff remaining unchanged, however, the recent decrease is associated with increased precipitation, now more than compensated for by increased melt driven runoff. Additionally, in three of the four models the equilibrium line altitude has risen since the mid-1990s, reducing the accumulation area at a rate of approximately 60 000 km2 per decade due to increased melting. Improving process representation requires further study but the use of a single accurate ice sheet mask is a logical way to reduce uncertainty among models. [less ▲]

Using Brand constellation to segment the market: a goal systemic perspective

Conference (2013, April 03)

This paper is aiming to expand the literature on consumption constellation by bridging the gap with the goal-oriented perspective and cognitive networks. We emphasize how brands could be considered as ... [more ▼]

This paper is aiming to expand the literature on consumption constellation by bridging the gap with the goal-oriented perspective and cognitive networks. We emphasize how brands could be considered as complementary means to reach high-level goals following the consumption constellation theory. This research also extend the knowledge on segmentation, first by recommending segmentation based on goals and means, and secondly by providing an operational method to capture these segments. Practically, we first collected data on the consumers’ hierarchy of goals in order to build a typology of goals and relate them to the consumers’ lifestyles. Secondly, brand constellations were elicited and mapped by the consumers, using brand concept mapping. Thirdly, network analytics were used to interpret the networks. [less ▲]

Adult Mesenchymal Stem Cells, Adult Neural Crest Stem Cells and Therapy of Neurological Pathologies: a State of Play

in Stem Cells Translational Medicine (2013), 2(4), 284-296

Adult stem cells are endowed with in vitro multi-lineage differentiation abilities, and constitute an attractive autologous source of material for cell therapy in neurological disorders. With regards to ... [more ▼]

Adult stem cells are endowed with in vitro multi-lineage differentiation abilities, and constitute an attractive autologous source of material for cell therapy in neurological disorders. With regards to lately published results, the ability of adult mesenchymal stem cells (MSC) and neural crest stem cells (NCSC) to integrate and differentiate into neurons once inside the central nervous system (CNS) is currently questioned. In this review, we collected exhaustive data on MSC/NCSC neural differentiation in vitro. We then analyzed pre-clinical cell therapy experiments in different models for neurological diseases and concluded that neural differentiation is probably not the leading property of adult MSC and NCSC concerning neurological pathologies management. Definitely, a fine analysis of the molecules that are secreted by MSC and NCSC would be of significant interest regarding their important contribution to the clinical and pathological recovery after CNS lesions. [less ▲]

A massive parsec-scale dust ring nebula around the yellow hypergiant Hen 3-1379

in Astronomy and Astrophysics (2013), 552

On the basis of far-infrared images obtained by the Herschel Space Observatory, we report the discovery of a large and massive dust shell around the yellow hypergiant Hen 3-1379. The nebula appears as a ... [more ▼]

On the basis of far-infrared images obtained by the Herschel Space Observatory, we report the discovery of a large and massive dust shell around the yellow hypergiant Hen 3-1379. The nebula appears as a detached ring of 1 pc diameter which contains 0.17 M[SUB]&sun;[/SUB] of dust. We estimate the total gas mass to be 7 M[SUB]&sun;[/SUB], ejected some 1.6 × 10[SUP]4[/SUP] years ago. The ring nebula is very similar to nebulae found around luminous blue variables (LBVs) except it is not photoionized. We argued that Hen 3-1379 is in a pre-LBV stage, providing direct evidence that massive LBV ring nebulae can be ejected during the red supergiant phase. [less ▲]

Fast-evolving weather for the coolest of our two new substellar neighbours

E-print/Working paper (2013)

We present the results of an intense photometric monitoring in the near-infrared (~0.9 microns) with the TRAPPIST robotic telescope of the newly discovered binary brown dwarf WISE J104915.57-531906.1, the ... [more ▼]

We present the results of an intense photometric monitoring in the near-infrared (~0.9 microns) with the TRAPPIST robotic telescope of the newly discovered binary brown dwarf WISE J104915.57-531906.1, the third closest system to the Sun at a distance of only 2 pc. Our twelve nights of photometric time-series reveal a quasi-periodic (P = 4.87+-0.01 h) variability with a maximal peak-peak amplitude of ~11% and strong night-to-night evolution. We attribute this variability to the rotational modulation of fast-evolving weather patterns in the atmosphere of the coolest component (~T1-type) of the binary. No periodic signal is detected for the hottest component (~L8-type). For both brown dwarfs, our data allow us to firmly discard any unique transit during our observations for planets >= 2 Rearth. For orbital periods smaller than ~9.5 h, transiting planets are excluded down to an Earth-size. [less ▲]

Les empereurs julio-claudiens et les lettres grecques

Conference (2013, April)

Compte-rendu de l'ouvrage de A. Beyaert-Geslin: Sémiotique du design

in Questions de Communication (2013), 23

Contrôle de l'azote potentiellement lessivable dans le sol en début de période de lixiviation. Etablissement des valeurs de référence

in Vandenberghe, Christophe; Colinet, Gilles; Destain, Jean-Pierre (Eds.) et al 2ème Atelier Nitrate - Eau. Evaluation du Programme de Gestion Durable de l'Azote (2013)

Based on observations in the field, for ten years, Gembloux Agro-Bio Tech (ULg) and the Catholic University of Louvain set annual benchmarks for nitrate-nitrogen concentrations in the soil at the ... [more ▼]

Based on observations in the field, for ten years, Gembloux Agro-Bio Tech (ULg) and the Catholic University of Louvain set annual benchmarks for nitrate-nitrogen concentrations in the soil at the beginning of the leaching period (referred to as ‘PLN’ - Potentially Leachable Nitrogen). These values are used as a reference to monitor farmers located in vulnerable zones, with the monitoring being carried out by the Public Service of Wallonia. Soil samples were taken twice a year (October and December) from approximately 250 plots subjected to reasoned nitrogen fertilization. The plots were located within 34 reference farms (constituting the Agricultural Survey Areas). The samples were then analyzed for nitrate-nitrogen content. The results allowed to establish reference values for eight classes of cultivation or meadow. Analysis of the results recorded in 2011, as in previous years, illustrates the importance of “crop” and “year” in establishing reference values. [less ▲]

Suivi de la lixiviation du nitrate en plein champ par la technique lysimétrique : retour de huit années d'expérience

in Vandenberghe, Christophe; Colinet, Gilles; Destain, Jean-Pierre (Eds.) et al 2ème Atelier Nitrate - Eau. Evaluation du Programme de Gestion Durable de l'Azote (2013)

Since 2003, nitrate leaching has been monitored in six plots located in a loamy area (Hesbaye, Belgium), mainly dedicated to wheat, sugarbeet and vegetable crops. Open-field lysimeters have been used in ... [more ▼]

Since 2003, nitrate leaching has been monitored in six plots located in a loamy area (Hesbaye, Belgium), mainly dedicated to wheat, sugarbeet and vegetable crops. Open-field lysimeters have been used in order not to impede agricultural operations. Lysimeters are used as follow-up tools to quantify the amounts of nitrate leaching below the root zone. This study aims to evaluate the suitability of PLN (Potentially Leachable Nitrogen – APL in French) defined in the Sustainable Nitrogen Management Program (PGDA in French) as an environmental indicator by relating nitrogen management practices (including fertilization recommendations) to PLN values and groundwater quality. This study demonstrates that lysimeters are efficient in collecting representative amounts of leaching water. Lysimeters show that PLN is identified as being related to the nitrate content in leaching water, which will not be taken up by the next crop. The amount of nitrate leaching below the root zone demonstrates the necessity and the relevance of the organic nitrogen spreading limits defined in the Sustainable Nitrogen Management Program. The lysimeter tool also shows that respect for leaching water quality standards under agricultural plots needs to be considered from an integrated and generalized approach, taking into account complete crop sequences and rotations, including rational fertilization rates and the introduction of catch crops in rotation. Some suitable or unsuitable crop sequences with regard to good groundwater quality are listed. [less ▲]