85 research outputs found
Investigations on the Polarimetric Behavior of a Target Near the Soil
No full textThe polarimetric behavior of the diffracted field from an object located close to the ground is investigated for a varying incidence angle. Here, the field is described by the geometrical theory of diffraction in accordance to its asymptotic formulas. As a result, a ray system composed of 13 different rays was implemented for the monostatic case by applying the principle of Fermat. The different spatial and creeping waves give a physical insight in the mechanisms involved in the entire scattering process. By varying the angle from perpendicular to grazing incidence 0°–90°, geometrical surface shadow boundaries are present for the backscattered field. At such boundaries, the spatial waves are replaced by their corresponding creeping waves, leading to a strong attenuation. The diffracted field for look angles related to the transition zones has a characteristic polarimetric behavior, which can be represented on the PoincarÉ sphere. The typical locations on the sphere can be exploited to get information about the geometrical parameters of the target and its height above the ground
Experimental Anechoic Chamber Measurements of a Target Near an Interface
No full textAbstract-The backscattered field of an illuminated sphere with diameter Ø = 30.5 cm above a perfect conducting plate is measured in an anechoic chamber at different heights for a varying incidence angle φ in the range 5° to 75°. A high frequency field λ « Ø is transmitted, so that two significant transitions from lit to shadow regions are given over the entire incidence angle range for the considered ray field. The polarimetric behavior of the measured scattering matrix [S] is investigated by using the common coherent and incoherent decomposition theorems used by the radar polarimetry scientific community. Close to the shadow boundaries the polarimetric behavior of the sphere significantly changes. Representing the different decomposition parameters used in radar polarimetry over the incidence angle range, the transition zones are related to local maxima or minima. Hence, the extreme values of the polarimetric parameters give information about the geometrical parameters e.g target size and its height above the plate
WP4430 Ground Based System
No full textThe requirements of a possible HF ground based radar system as required for a continuous observation over a large ocean area is investigated. In these studies the basic geophysical tsunami parameters which are accessible for a HF radar remote sensing system are summarised and discussed. Here, the interaction of a High Frequency field HF (3–30 MHz) with ocean waves is of particular interest and therefore reviewed in details. An approaching Tsunami determines a relevant departure from standard ocean surface current patterns. By continuously monitoring the current field with a HF radar ground based system along the coastline, a potentially dangerous Tsunami could be accurately detected when the first wave front is still sufficiently far from the shore. The Doppler resolution for Tsunami induced surface currents is investigated by the Fourier transformed of two synthetic generated HF time series, backscattered from an illuminated ocean surface patch. The temporal evolution of the ocean surface is performed by a phase modulation in the Fourier domain
Investigations on the Polarimetric Behavior of a Target near the Soil
No full textThe diffraction of a plane wave by an object situated close to an interface of a two-layer medium has been investigated by many authors and an extensive literature exists on this topic. However, only a few publications have been devoted to the analysis of the polarimetric behaviour of the diffracted field. In general, very simple ray models based on the Geometrical Optic (GO) are considered involving single and double bounced waves for explaining some experimental results. Here, this problem is again investigated by using a more refined ray model based on the Geometrical Theory of Diffraction (GTD). As a result a ray system composed of 13 different rays was implemented for the monostatic case by applying the principle of Fermat. The different spatial and creeping waves give a physical insight in the mechanisms involved in the entire scattering process. Depending on the geometrical properties of the target, lit and shadow regions arise in the backscattered GTD field for a variation from perpendicular to grazing incidence for a monostatic alignment of the transmitting and receiving antenna. The separating line of such a lit and shadow region is called a Surface Shadow Boundary (SSB). A special emphasis is attributed to the transition regions near the shadow boundaries where the reflected spatial waves disappear and transform into creeping waves leading to a strong attenuation. The diffracted field for look angles related to the transition zones has a characteristic polarimetric behaviour which is represented on the Poincaré sphere. The typical locations on the sphere can be exploited in order to get information about the geometrical parameters of the target and its height above the ground
A Refined GTD Ray System for an Embedded Object and its Polarimetric Behavior
No full textA refined ray system based on the Geometrical Theory of Diffraction
(GTD) for an object embedded in soil for a monostatic
transmitter-receiver alignment is presented here. Apart from the
investigation of the ``classical" reflections from the target,
creeping waves are also taken into account and their formalism is
presented. The objective of such a ray set is to better understand
the different scattering mechanisms, which are presented in the
complex scattering framework. In electromagnetic modelling based on
GTD, a complex shape of a target is replaced by simpler canonical
objects e.g. facets, cones, wedges, spheres or cylinders. Here, a
cylinder is located in parallel and closely to the plane interface
of two dielectrics half-spaces. In this paper, an example of
air-soil is taken into analysis. The numerical results obtained from
a varying incidence field are employed to describe the polarimetric
characteristics of the diffracted field from grazing to
perpendicular incidence for a transceiver. By representing the
diffracted GTD field on the Poincaré sphere, the location on the
sphere has a one-to-one relationship to the dielectric properties of
the soil
Globalization, Social Movements, and the Construction of Europe: The Example of the European Parliament Elections in France, CES Working Paper, no. 74, August 2000
Get PDFThough social scientists have lately devoted themselves to the study of globalization (Waters 1995; Hirst and Thompson 1999), most of these studies have concentrated on its economic and social consequences. Globalization is often seen as a fundamentally unjust process that causes confusion and destroys more than it creates. In many areas, the substantive implications of globalization are left untouched. In this paper, I examine the link between regional integration in Western Europe and the transformation of domestic politics through the example of the European Parliament elections. I argue that globalization through European integration is having a significant impact on French domestic politics. More precisely, the elections to the European Parliament, a supranational political institution, have contributed to the political mobilization of traditionally voiceless groups such as the unemployed and to the introduction into public discussion of new issues tied to Europe, transforming political culture and the relationship between national politics and multinational bargaining (Keohane and Hoffmann 1990, 295). Not only has European political integration provided marginal groups in France with an access to national politics through European Parliament elections, it has also supplied the government and the presidency with new resources, connecting them to trans-European circles and networks that are developing their own political culture. The success of neoliberal economic doctrines in the European Union may have in part to do with these networks. National ministers spend half their time wrestling with European affairs in the Council of Ministers of the European Union and in transnational party structures, developing a common culture and outlook on politics and economics. The main ingredients for this Weltanschauung are well known: electoral cycles should not interfere with economic policy and unemployment figures should not have priority over other monetary indices in the evaluation of economic and political success
Keeping the promise of global accounting standards
Get PDFAccounting provides a fundamental underpinning for capital markets, and the worldwide spread of International Financial Reporting Standards (IFRS) marks one of the most advanced attempts to develop globally consistent financial rules.
The financial crisis has generated heated debate on the economic role of fair-value accounting and other IFRS principles. Underlying these controversies are differing views about the mission and governance of accounting standard-setters, and how standards interact with other public policy instruments. Choices are made more difficult by the absence of relevant precedents for the unique institutional features of the global standard-setting organisation, the IFRS Foundation.
Recherche de discriminants polarimétrique dans la diffraction par des objets situés à proximité de l'interface plan entre deux milieux diélectriques à pertes
No full textLe comportement polarimétrique d'un champ électromagnétique diffracté par un cible localisée à l'interface air-sol est analysée pour une onde incidente variant de l'incidence normale à l'incidence rasante. Le champ rétrodiffusé dans le cas monostatique est analysé au moyen de la théorie géométrique de la diffraction (G.T.D) ou la méthode étalon. Dans cette thèse, un modèle de rayon précis a été implémenté. Une attention toute particulie re a été portée aux zones de transition, où proches de telles frontières d'ombre, les rayons réfléchis disparaissent et se transforment en rayons rampants sur la cible et sont fortement atténués dans la zone d'ombre. Les études ont montré que les éléments de la matrice de Sinclair [S] et les états de polarisation caractéristiques associés présentent une variation rapide sur la sphère de Poincaré. Les localisations significatives sur la sphère de Poincaré peuvent être exploitées afin d'extraire l'information sur les paramètres géométriques ou les propriétés géophysiques de l'environnement.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF
Le chemin de l’Alsace. Premières lectures de Tristan et Bertrade. Histoire gauloise, un roman manuscrit de Kerenveyer
No full textInternational audienceDated 1765, Tristan et Bertrade. Histoire gauloise is the title of a manuscript written by François-Nicolas Pascal de Kerenveyer (1729–1794). Inspired by an essay on ‘l’origine des lettres françoises’ (dated 1664) and dedicated to Mademoiselle d’Arimont, the woman who was to become his wife the following year, it is far removed from his Breton collection Ar farvel göapaër/Le bouffon moqueur. Behind the awkwardness of the romance, the author sheds light on some of the debates of his time. Kerenveyer genuinely seems to be parading sensualism in this text. The actions of Tristan and Bertrade are the product of their all-consuming sensations. However, this romance also reveals the culture of a Breton gentleman in search of recognition.Daté de 1765, Tristan et Bertrade. Histoire gauloise est le titre d’un manuscrit de François-Nicolas Pascal de Kerenveyer (1729-1794). Derrière les maladresses d’un roman inspiré par une dissertation sur « l’origine des lettres françoises » (datée de 1664), dédicacé à Mademoiselle d’Arimont, celle qui deviendra sa femme l’année suivante, et fort éloigné de son recueil breton Ar farvel göapaër / Le bouffon moqueur, l’auteur met en lumière quelques débats de son temps. En effet, dans son texte, Kerenveyer semble bel et bien mener une démonstration sensualiste : les actions de Tristan & Bertrade sont le fruit des sensations qui les habitent. Mais ce roman témoigne aussi de la culture d’un gentilhomme breton en quête de reconnaissance
Le chemin de l’Alsace
Get PDFDaté de 1765, Tristan et Bertrade. Histoire gauloise est le titre d’un manuscrit de François-Nicolas Pascal de Kerenveyer (1729-1794). Derrière les maladresses d’un roman inspiré par une dissertation sur « l’origine des lettres françoises » (datée de 1664), dédicacé à Mademoiselle d’Arimont, celle qui deviendra sa femme l’année suivante, et fort éloigné de son recueil breton Ar farvel göapaër / Le bouffon moqueur, l’auteur met en lumière quelques débats de son temps. En effet, dans son texte, Kerenveyer semble bel et bien mener une démonstration sensualiste : les actions de Tristan & Bertrade sont le fruit des sensations qui les habitent. Mais ce roman témoigne aussi de la culture d’un gentilhomme breton en quête de reconnaissance.Dated 1765, Tristan et Bertrade. Histoire gauloise is the title of a manuscript written by François-Nicolas Pascal de Kerenveyer (1729–1794). Inspired by an essay on ‘l’origine des lettres françoises’ (dated 1664) and dedicated to Mademoiselle d’Arimont, the woman who was to become his wife the following year, it is far removed from his Breton collection Ar farvel göapaër/Le bouffon moqueur. Behind the awkwardness of the romance, the author sheds light on some of the debates of his time. Kerenveyer genuinely seems to be parading sensualism in this text. The actions of Tristan and Bertrade are the product of their all-consuming sensations. However, this romance also reveals the culture of a Breton gentleman in search of recognition
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