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The rigorous solution of the scattering by two-dimensional rough surfaces can be numerically performed thanks to the sparse matrix flat surface iterative approach (SMFSIA). However, this kind of computation still requires both large CPU time and memory. Consequently, a lot of work has been dedicated at extending the domain of validity of approximate methods beyond that of standard high and low frequency approximations. In this paper it is shown that SMSFIA can be simplified in order to get a fast approximate method, with low memory requirements. This approximation is valid for surfaces with small slopes, and covers the domain of validity of both the Kirchhoff-tangent plane approximation and the first-order small slope approximation [1]. Index Terms--Ocean remote sensing, rough surface scattering.

Two holographic diffraction gratings with very similar parameters, designed for maximum performance in TM polarization, are investigated, their diffraction efficiency measured, an electron microscopic picture of their surface observed, and numerical simulation of light diffraction done with the surface roughness taken into account. It is demonstrated numerically that a small-scale roughness imposed on the grating surface could increase significantly both scattering and absorption from the surface, this influence being greater in the TM case. A very good coincidence between the numerical and experimental data is obtained in TE polarization, whereas in TM polarization only a qualitative agreement exists.

We show numerically that surface modes are associated with poles of the scattering operator in the complex plane of wavelengths, which permits one to excite a mode strongly in such a way that the amplitudes of the incident wave and of the waves scattered in the air are negligible. Then the shape of the surface mode clearly appears, and localization effects are well isolated. The influence of Bragg resonances on the location of the poles of the scattering operator in the complex plane was studied.

The work presented here aims at interpreting the pattern observed at low frequencies in wavenumber‐frequency (k,ω) representations (dispersion diagrams) of radar returns from sea surface. This pattern is sometimes referred to as the "group line" in the literature and is supposed to result from the nonlinear behavior of the signal with respect to surface profile. To confirm this assumption, we have calculated the patterns generated by various nonlinear terms of second order in sea surface height. It is shown that the resolution in frequency of most data is not sufficient to allow for an accurate representation of the group line through an FFT. A methodology is proposed to define an average slope of the group line, which can be interpreted in terms of velocity. Key Points: Two‐dimensional spectra were extracted from radar returns from sea surfaceA pattern is observed at low frequencies in wavenumber‐frequency spectraThe characteristics of this pattern have been explicitly linked to the spectrum of waves [ABSTRACT FROM AUTHOR]

Wavenumber‐frequency spectra are obtained by performing a two‐dimensional Fourier transform of range‐time normalized radar cross‐section (NRCS) or Doppler velocity maps. In such diagrams, some energy is present at low space‐time frequencies, resulting from the nonlinear behavior of the measured quantity related to the sea surface geometry. This feature is called the group line, since for a narrow‐band wave packet the energy is concentrated along a straight line with group velocity as slope. Which physical nonlinear process generates the group line remains an open question. Breaking waves have been proposed as the most probable contributor. However, numerical simulations from weakly nonlinear surfaces without breaking events and experiments performed at low winds also provide such feature. In a companion paper, a theoretical and numerical analysis has permitted to predict the energy distribution of the group line depending on the kind of nonlinearity. It provides some means to characterize a group line in a rigorous way. In this paper, it is used to analyze the group lines derived from the experimental MARLENE data. The group lines computed from the backscattering amplitude behave as the one of the square of sea surface slopes. The analysis of the Doppler velocities provides similar results, which significantly differ from what is expected if breaking waves are the main contributors and do break at velocities reported in the literature. Our results suggest that the group line mainly reflects the asymptotic behavior of the scattering amplitude at grazing incidence, of which the leading nonlinear term is proportional to the square of surface slope. Key Points: A comparison of the analytical model of the group line with experimental data has been performedIn terms of group line, experimental data behave as the square of the slope of the surfaceThe group line is not the signature of the breaking waves [ABSTRACT FROM AUTHOR]

Presents information on a study that provided a better insight into the shallow donors induced by proton implantation and subsequent annealing at temperatures greater than or equal to 300 degrees centigrade. Experimental procedure; Results and discussion on the study.

Abstract: The link between plate tectonics and the evolution of active margins is still an ongoing task to challenge since the acceptance of plate tectonic paradigm. This paper aims at deciphering the structural architecture and uplift history of the North Peruvian forearc system to better understand the evolution and the mechanics that govern the Late Cretaceous‐Cenozoic building of this active margin. In this study, we report surface structural geology data, interpretation of seismic reflection profiles, apatite fission track data, and the construction of two offshore‐onshore crustal‐scale balanced cross sections. The structure of the North Peruvian forearc system is dominated by an accretionary style with northwestward propagation of thrust‐related structural highs involving continental/oceanic basement rocks and off‐scrapped sediments. The thrust systems bound thick thrust‐top forearc depocenters mainly deformed by crustal normal to strike‐slip faults and thin‐skinned gravitational instabilities. The sequential restoration of the margin calibrated with apatite fission track data suggests a correlation between uplift, shortening, and plate convergence velocity during Late Cretaceous and Miocene. Pliocene‐Quaternary shortening and uplift of the coastal zone is rather related to the subduction of asperities during convergence rate decrease. The development of crustal normal to strike‐slip faulting and subsidence zones might be the consequence of slab flexure, local basal erosion along subduction fault, and/or oblique subduction associated with sediment loading control. We conclude that the evolution of the North Peruvian forearc system was controlled by subduction dynamics, strong sediment accumulation, and recent ridge subduction, and it recorded the orogenic loading evolution of the Andes over the Cenozoic. [ABSTRACT FROM AUTHOR]

Measurement of interseismic strain along subduction zones reveals the location of both locked asperities, which might rupture during megathrust earthquakes, and creeping zones, which tend to arrest such seismic ruptures. The heterogeneous pattern of interseismic coupling presumably relates to spatial variations of frictional properties along the subduction interface and may also show up in the fore-arc morphology. To investigate this hypothesis, we compiled information on the extent of earthquake ruptures for the last 500 years and uplift rates derived from dated marine terraces along the South American coastline from central Peru to southern Chile. We additionally calculated a new interseismic coupling model for that same area based on a compilation of GPS data. We show that the coastline geometry, characterized by the distance between the coast and the trench; the latitudinal variations of long-term uplift rates; and the spatial pattern of interseismic coupling are correlated. Zones of faster and long-term permanent coastal uplift, evidenced by uplifted marine terraces, coincide with peninsulas and also with areas of creep on the megathrust where slip is mostly aseismic and tend to arrest seismic ruptures. We conclude that spatial variations of frictional properties along the megathrust dictate the tectono-geomorphological evolution of the coastal zone and the extent of seismic ruptures along strike. [ABSTRACT FROM AUTHOR]

This paper documents the study of the radar signature of the sea surface on the images collected by an X-band weather radar and its application to remote sensing of the coastal zone. The main radar parameters considered here are the reflectivity factor [which was converted into a normalized radar cross section (NRCS)], the differential reflectivity, and the mean radial velocity. Measurements of the NRCS in the vicinity of an instrumented offshore buoy allowed for identifying its variations with wind speed and relative direction, which are found to be consistent with the Georgia Institute of Technology (GIT) model and other measurements. A more accurate empirical model for the NRCS is developed. For moderate to strong winds, the mean radial velocity is linearly related to the radial component of the wind speed, showing the potentiality of weather radars to map the radial surface wind speed at the scale of a basin. The influence of surface currents is weak here but should be likely taken into account in other places with stronger currents. Measurements of the differential reflectivity are also consistent with other measurements made elsewhere for the polarization ratio. The analysis of radar data over the entire coverage could also be performed using surface wind estimates from a meteorological model. Similar but less accurate results are obtained for the NRCS and the mean radial velocity. The extra spatial variability not due to wind speed variations is identified. An inversion procedure is proposed to recover the wind vector field from radar measurements after calibration of the NRCS values. Results are promising and pave the way to the concept of weather radar for ocean remote sensing. [ABSTRACT FROM AUTHOR]

We present a boundary integral method for the numerical solution of the rigorous problem of wave scattering from rough surfaces under grazing illumination. The model of a locally perturbated plane is adopted: a finite patch of rough surface has its roughness flattened at the edges. The boundary formulation unknowns are the tangential components of the scattered field, defined as the contribution from the rough area. This way, the numerical domain of study is correctly bounded, even with a plane wave as incident field, and the sampled area is made independent of the incidence. This rigorous approach, called the grazing method of moments, is implemented on two-dimensional perfectly conducting surfaces and validated by comparison with a reference numerical solution for surfaces with Gaussian correlation functions. Now, the validity of approximate models at low-grazing-angles can be investigated; the small perturbation method and the small slope approximation are addressed in this paper. Scattering diagrams show how the performances of these methods deteriorate drastically at backward scattering angles as the incidence goes to grazing. [ABSTRACT FROM PUBLISHER]

This paper deals with the detection of a buried object beneath a rough surface in a two-dimensional configuration. A new method for detecting buried objects from wide-band, near-field, multi-static data is suggested. The so-called near-field configuration corresponds to a set of transmitters and receivers located along a line segment in the vicinity of the surface. The detection method proposed here is based on a correlation of the scattered fields from two sets of data associated with two transmitters. A theoretical study in the framework of a low-frequency approximation predicts an enhancement of the correlation peak resulting from cross-terms combining surface and target contributions, as confirmed by rigorous computations. The performance of the detector is tested with respect to both polarization and frequency through computation of the receiver operating characteristic curves. [ABSTRACT FROM AUTHOR]

This letter considers the problem of detecting and characterizing a target buried beneath a rough surface separating two homogeneous half spaces. The problem of detecting the target is tackled by analyzing the frequency-averaged Wigner-Ville function, the purpose of which is to filter out rough surface scattering. Characterization of the target is performed using the iterative solution derived from the Newton-Kantorovitch algorithm as applied to the Wigner-Ville function instead of the scattered field as is usually done. In addition, the scattering model involved in the inversion scheme assumes a flat interface, and surface roughness is handled as clutter. The efficiency of the approach is illustrated through numerical experiments, and the comparison between inversions from the scattered field and the Wigner-Ville function is reported [ABSTRACT FROM PUBLISHER]

Presents a study which examined the reconstructions from a measured scattering field of two dimensional (2D) dieelectric or conducting objects from multi-frequency experimental data. Theoretical background; Computational approach; Numerical results and discussion.

The method of decomposition of the time reversal operator has been introduced with the aim of focusing acoustic waves on a selected target. It is based on the derivation of the invariants of the time reversal operator, which is linked to the transfer matrix of the array of transducers insonifying a time invariant scattering medium. The theoretical and numerical results concern independent point-like scatterers. Here, we apply numerically the same technique to electromagnetic waves, and all the interactions between the various scatterers are taken into account. This method may be very useful to detect and localize buried objects. With this goal, we have investigated the role of polarization and of the geometrical or electromagnetic parameters, as well as the ability of accurately focusing on a scatterer. The sensitivity of the results to the initial set of data, namely the number of measurements or the accuracy, is also studied. [ABSTRACT FROM AUTHOR]

Provides technique for the numerical solution of 2-D electromagnetic scattering with 3-D sources. Factor of the electromagnetic interactions; Formulation of the homogenous domains; Computation of the linear equations.

According to the Hygiene Package Regulations, European Member States encourage the development and dissemination of national guides to good practice for hygiene and for the application of HACCP principles. These guides are developed by food business sectors. Within the oilseed crops food chain, such guides are developed at different stages: primary production of oilseed crops, collection and storage of seeds, oilseeds crushing and refining industry. This article presents these three guides developed in France by the federations of concerned operators. We describe how these guides are constructed, their scope, their progress in the validation process by the authorities, the health hazards identified, best practices by sector and HACCP study.

Scientific research has evolved to identify relationship between nutrients and health effects. Theses scientific evidences can help to establish public health recommendations, which will be used by operators to formulate or optimize their food products. Labelling serves as a support for consumer information, raising its awareness about the food product nutritional composition. This enables the consumer to make an informed choice. Labelling also participates in the promotion of some of the food components, e.g. essential fatty acids in vegetable oils. In this context, regulation has evolved and allows operators to highlight nutritional benefits of their products via labelling information. Two different types of information must be distinguished: nutrition labelling and nutrition or health claims. The new European Regulation 1169/2011 on the provision of food information to consumers, published at the end of 2011, establishes a mandatory nutrition labelling with a fixed list of nutrients. Hence, food manufacturers are required to label the energy, fat, saturated fat, carbohydrate, sugars, protein and salt content of all their products. The Regulation on nutrition and health claims made on foods, published at the end of 2006, applies stringent rules to the use of claims and introduces the concept of a positive list for nutrition and generic health claims. This regulation aims at supporting public health recommendations and at providing the consumer with a high level of protection. A number of claims can be applied to vegetable oils. Nutrition labelling is an essential tool to disseminate and popularize scientific information in order to outreach consumers, as in the case of fatty acids, plant sterols or fat-soluble vitamins labeled in vegetable oils.

Les huiles d’olives bénéficient d’une forte image santé auprès des consommateurs. Pourtant il y a peu d’allégations nutritionnelles et de santé autorisées par la Commission pour ces huiles. On peut citer par exemple « riche en acides gras insaturés », « riche en vitamine E » ou des allégations plus élaborées telles que «Les polyphénols présents dans l’huile d’olive contribuent à protéger les lipides sanguins contre le stress oxydatif» ou « Le remplacement de graisses saturées par des graisses insaturées dans le régime alimentaire contribue au maintien d’une cholestérolémie normale ». D’autres effets santé bénéfiques ont pu être mis en évidence dans le régime méditerranéen grâce à certaines études : par exemple l’amélioration des fonctions cognitives (projet COGINUT) ou des fonctions cardiovasculaires (étude PREDIMED), sans toutefois avoir d’allégations autorisées correspondantes. Des recherches supplémentaires sont nécessaires pour mieux comprendre le rôle de l’huile d’olive (et sa composition en acides gras et polyphénols) dans ces fonctions.