A multi-temporal method for cloud detection, applied to FORMOSAT-2, VENµS, LANDSAT and SENTINEL-2 images

Over lands, the cloud detection on remote sensing images is not an easy task, because of the frequent difficulty to distinguish clouds from the underlying landscape, even at a high resolution. Up to now, most high resolution images have been distributed without an associated cloud mask. This situation should change in the near future, thanks to two new satellite missions that will provide optical images combining 3 features: high spatial resolution, high revisit frequency and constant viewing angles. The VENµS (French and Israeli cooperation) mission should be launched in 2012 and the European SENTINEL-2 mission in 2013. Fortunately, two existing satellite missions, FORMOSAT-2 and LANDSAT, enable to simulate the future data of these sensors.Multi-temporal imagery at constant viewing angles provides a new way to discriminate clouded and unclouded pixels, using the relative stability of the earth surface reflectances compared to the quick variations of the reflectance of pixels affected by clouds. In this study, we have used time series of images from FORMOSAT-2 and LANDSAT to develop and test a Multi-Temporal Cloud Detection (MTCD) method. This algorithm combines a detection of a sudden increase of reflectance in the blue wavelength on a pixel by pixel basis, and a test of the linear correlation of pixel neighborhoods taken from couples of images acquired successively.MTCD cloud masks are compared with cloud cover assessments obtained from FORMOSAT-2 and LANDSAT data catalogs. The results show that the MTCD method provides a better discrimination of clouded and unclouded pixels than the usual methods based on thresholds applied to reflectances or reflectance ratios. This method will be used within VENµS level 2 processing and will be proposed for SENTINEL-2 level 2 processing.     

Détection des plantes envahissantes par télédétection : un cas d'étude,l'ambroisie en région Rhône‐Alpes,France

L'ambroisie, Ambrosia artemisiifolia, est une plante annuelle responsable d'allergies respiratoires dues à son pollen. Dans certains secteurs du département du Rhône, jusqu'à 20% de la population a été atteinte d'allergie respiratoire en 2005. Ce problème majeur de santé touche actuellement six des huit départements de la Région Rhône‐Alpes (Ain, Ardèche, Drôme, Isère, Loire et Rhône). L'un de nos objectifs est de mettre au point une méthode qui permette de cartographier, dans un premier temps à l'échelle d'une commune, puis à terme à l'échelle d'un département l'infestation par l'ambroisie. En se basant sur les méthodes développées par Auda et al. (2002a Auda, Y., Blasco, F., Gastellu, J.‐P., Marty, G. and Dechamp, C. 2002a. Essai préliminaire de détection des champs d'Ambroisie (Ambrosia artemisiifolia) par télédétection spatiale.. Revue française d'allergologie et d'immunologie clinique, 42: 533–538.  [Google Scholar]), nous avons inventorié, à la fin juillet, l'infestation par l'ambroisie dans la commune d'Estrablin (Isère). Pour chaque parcelle inventoriée, le type de culture et l'importance de l'infestation ont été enregistrés dans un Système d'Information Géographique. Les parcelles échantillonnées couvrent 3650 km², soit 30% de la surface de la commune. Ces données serviront à valider une image multispectrale Spot 5 du 16 août 2005. L'interprétation des données terrain souligne l'importance de l'infestation. En effet, 93% des surfaces échantillonnées sont infestées. L'analyse se poursuit par une classification par le maximum de vraisemblance de l'image Spot 5 qui repose sur une thématique croisant le type de culture et l'importance de l'infestation. Le pourcentage de pixels bien classés (45%), la logique des confusions observées et la cohérence visuelle des représentations cartographiques des résultats témoignent de l'efficacité de la méthode de détection des zones infestées. La performance de cette méthode apparaît largement tributaire de la disponibilité d'images de bonne qualité au moment adéquat. Son caractère opérationnel qui est donc étroitement lié à ces contraintes techniques, est discuté en fonction des programmes des Agences Spatiales.

Ragweed, Ambrosia artemisiifolia, is an annual plant, the pollen of which is responsible for respiratory allergies. In 2005, these allergies affected up to 20% of the population in parts of the department of Rhône. This is a major health problem for six of the eight departments of the Rhône‐Alpes region (Ain, Ardèche, Drôme, Isère, Loire and Rhône). Our objective was to validate a method to map ragweed infestation in a village and then to extend this experiment to a department. Using methods developed by Auda et al. (2002a Auda, Y., Blasco, F., Gastellu, J.‐P., Marty, G. and Dechamp, C. 2002a. Essai préliminaire de détection des champs d'Ambroisie (Ambrosia artemisiifolia) par télédétection spatiale.. Revue française d'allergologie et d'immunologie clinique, 42: 533–538.  [Google Scholar]), we undertook a survey of ragweed infestation at the end of July 2005 in the village of Estrablin (Isère). Plots of land were registered in a Geographical Information System, with indications of crop type and ragweed infestation included in each plot. The sample area covered 3650 km² and constituted 30% of the total area of the village. The data were used to validate a SPOT 5 multispectral satellite image captured on 16 August 2005. Analysis of the ground data confirmed the extent of the ragweed infestation. More than 90% of the sample area was found to be infested. The image processing was based on crossing the crop type with the degree of infestation, using maximum likelihood classification. The accuracy of the method of detection used was demonstrated by the percentage of correctly classified pixels (45%), the reasons for confusion and the clarity of the visual representations. The success of our approach is highly influenced by the availability of high‐quality images. Its feasibility, which is linked therefore to technical constraints, is examined in relation to space agency programmes.     

On the prediction of residual stresses in automated tape placement

Thermoplastic automated tape placement process allows the manufacture of large composite parts. This method is based on the continuous welding by fusion bonding of a thermoplastic matrix composite ply on a substrate. It has received an increasing interest in recent years due to its ability to produce parts out of autoclave. In order to control and optimize the quality of the part, accurate predictions of the thermo-mechanical history applied during the manufacturing of the laminate are needed, usually through the numerical solution of the involved thermo-mechanical models. In a former work a parametric thermal modeling was successfully accomplished. The present work focusses on the thermo-mechanical modeling able to predict the residual stresses installed in the part during the forming process. An efficient (fast and accurate) thermo-mechanical solver for predicting residual stresses is compulsory for optimizing the process.     

Decontamination efficiency of poly(hydroxybutyrate-co-valerate)-based food packaging material: The role of the chemical structure of contaminants and additive

Recycled plastic materials can only be placed in the market if they are free from contaminants at harmful levels. This work studies the thermal decontamination of poly(hydroxybutyrate-co-valerate) (PHBV) intended for food contact. PHBV was first contaminated with gallic acid, catechin, ferulic acid, and PEG 200, at 500 mg/kg. Thermal decontamination was then applied at 160°C for 6 and 48 h. Due to the low volatility of these molecules and their hydrogen bonding interactions with the polymer, decontamination efficiency was well below safety limits. Indeed, only 25.9% of gallic acid, 68.5% of catechin, 67% of ferulic acid, and 86.8% of PEG 200 were removed. In addition, a strong degradation of the polymer was observed (M_w decrease of 57%). To try to prevent polymer degradation, while enhancing decontamination conditions, quercetin (a natural polyphenol) was used as a stabilizer at 0.5 wt%. After 6 h of decontamination, hydrogen bonds, and π-stacking interactions were formed between quercetin and the contaminants, reducing their removal (−8.5% for gallic acid, −57.4% for catechin, −18.7% for ferulic acid, and −31.9% for PEG200). After 48 h, strong PHBV degradation was observed (−83% M_w and −45% X_c), particularly in the presence of quercetin.     

Assessing the impacts of the 2003 hot and dry spell with SPOT HRVIR images time series over south‐western France

A severe heatwave affected southern Europe and, in particular, south‐western France during the summer of 2003. The area was subjected to a severe dry spell with high temperatures and very little precipitation during a nearly 4‐month‐long period. A series of monthly 20‐m spatial resolution images, acquired between 2002 and 2003 by the SPOT HRVIR (High Resolution Visible–Infrared) was used to examine the impact of the dry and hot spell over a 50?km×50?km area of south‐western France. The use of the high spatial resolution data permitted the distinction of the various land surface types, and facilitated the diagnosis of the hot and dry spell effects for each class. The Normalized Difference Vegetation Index (NDVI) time series of the four principal vegetated surfaces (meadow, deciduous forest, wheat and maize) reveal different responses to the dryness and hot spell. A significant shortening of the 2003 phenological cycle was observed for the meadows, but the response was not as clear for the deciduous forests. For the crop surfaces, a shortening of the cycle is observed, although the impact of the drought was translated differently as a function of the crop type.     

Development of two PCR assays for the identification of mycoplasmas causing contagious agalactia

A new detection test for the mycoplasmas causing contagious agalactia, Mycoplasma agalactiae, M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C., was developed. It was based on two polymerase chain reaction assays: the Ma-PCR for the detection of M. agalactiae and the MYC-PCR for the 'mycoides cluster' thus including M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C. An M. agalactiae strain was identified by a 933-bp Ma-PCR product and no amplification with the MYC-PCR. In contrast, a 460-bp MYC-PCR product and a negative or a 350-bp Ma-PCR product characterized a 'mycoides cluster' strain. M. capricolum subsp. capricolum and M. mycoides subsp. mycoides L. C. were identified by their species-specific AseI pattern of the 460-bp MYC-PCR product.     

A 1.75-GHz highly integrated narrow-band CMOS transmitter withharmonic-rejection mixers

A highly integrated 1.75-GHz 0.35-μm CMOS transmitter is described. The I/Q modulator-based transmitter facilitates integration through the use of a unique mixer, termed a harmonic-rejection mixer, and a wide loop bandwidth phase-locked loop (PLL) for the RF synthesizer. The harmonic-rejection mixers are used to eliminate the need for a discrete IF filter and the use of a wide loop bandwidth PLL allowed for the complete integration of the synthesizers using low-Q components while achieving low phase noise. The entire transmit signal path from the digital-to-analog converters to the power amplifier, including two fully integrated frequency synthesizers, is integrated into a single-chip solution. The transmitter was tested with a testing buffer before the power amplifier (PA) and achieved less than 1.3° rms phase error when modulating a DCS-1800 GMSK signal. The prototype consumed 151 mA from a 3-V supply. A class-C PA, capable of driving 25 dBm off-chip, was included and the output was compared to the testing buffer with little change in the transmitter performance     

MtENOD16 and 20 are members of a family of phytocyanin-related early nodulins

We have identified two single-copy genes from the model legume. Medicago truncatula (MtENOD16 and 20) whose expression can be correlated with early stages of root nodulation and whose predicted coding sequences are partially homologous to both pea/vetch ENOD5 and soybean N315/ENOD55. Database searching and sequence alignment have defined the encoded early nodulins as a distinct sub-family of phytocyanin-related proteins, although the absence of key ligands implies that they are unlikely to bind copper. Molecular modelling based on known phytocyanin structure has been used to predict the 3-dimensional conformation of the principle globular domain of MtENOD16/20. Additional structural features common to both early nodulin and phytocyanin precursors include an N-terminal transit peptide, a highly variable (hydroxy)proline-rich sequence which probably undergoes extensive post-translational modification, and a hydrophobic C-terminal tail.     

Continuous-Action Q-Learning

This paper presents a Q-learning method that works in continuous domains. Other characteristics of our approach are the use of an incremental topology preserving map (ITPM) to partition the input space, and the incorporation of bias to initialize the learning process. A unit of the ITPM represents a limited region of the input space and maps it onto the Q-values of M possible discrete actions. The resulting continuous action is an average of the discrete actions of the winning unit weighted by their Q-values. Then, TD() updates the Q-values of the discrete actions according to their contribution. Units are created incrementally and their associated Q-values are initialized by means of domain knowledge. Experimental results in robotics domains show the superiority of the proposed continuous-action Q-learning over the standard discrete-action version in terms of both asymptotic performance and speed of learning. The paper also reports a comparison of discounted-reward against average-reward Q-learning in an infinite horizon robotics task.