Fusion d'informations multi-sources pour le suivi des coupes de canne à sucre à La Réunion

Dans ce papier on présente un système d'aide à la décision pour le suivi des coupes de canne à sucre qui intègre des informations provenant de trois sources hétérogènes : une série temporelle d'images satellite, un modèle de culture et des connaissances expertes. Le système est basé sur la logique floue, et ses règles sont générées automatiquement par un arbre de décision flou construit en s'appuyant sur un jeu d'apprentissage. Les performances du système sont analysées sur deux exploitations de canne à la Réunion en utilisant une série d'images SPOT-5. Les résultats montrent que le système peut être utilisé d'une façon opérationnelle : la précision globale en utilisant une série de 3 images par an est supérieure à 92 %; elle atteint 97 % avec 9 images par an. / Multi-source information fusion for sugarcane harvest monitoring in Reunion Island

Atmospheric corrections of low altitude thermal infrared airborne images acquired over a tropical cropped area

Corrections atmosphériques d'images thermiques de cultures tropicales acquises à basse altitude. / Accurate corrections of atmospheric effects on thermal infrared remote sensing data are an essential pre-requisite for the development of thermal infrared airborne-derived crop water stress indices. These corrections can be performed using ground surface temperature measurements, which are time consuming and expensive. Atmospheric effects can also be corrected using radiative transfer models that require knowledge of atmospheric status. The latter can be accurately characterized from radiosoundings, but these are usually unavailable. It can also be derived from meteorological model simulations, but spatial and temporal resolution are often too coarse. This study proposes performing atmospheric corrections by using temperature and relative humidity profiles acquired in flight from onboard sensors during data collection. Such measurements are used to document the atmospheric radiative transfer model MATISSE. First results from an experimentation over a tropical cropped area show that corrections are made with a 1.46 °K accuracy

Carbenic nitrile imines: Properties and reactivity

Structures and properties of nitrile imines were investigated computationally at B3LYP and CCSD(T) levels. Whereas NBO analysis at the B3LYP DFT level invariably predicts a propargylic electronic structure, CCSD(T) calculations permit a clear distinction between propargylic, allenic, and carbenic structures. Nitrile imines with strong IR absorptions above ca. 2150 cm-1 have propargylic structures with a CN triple bond (RCNNSiMe 3 and R2BCNNBR2), and those with IR absorptions below ca. 2150 cm-1 are allenic (HCNNH, PhCNNH, and HCNNPh). Nitrile imines lacking significant cumulenic IR absorptions at 1900-2200 cm -1 are carbenic (R-(C:)-N=N-R′). Electronegative but lone pair-donating groups NR2, OR, and F stabilize the carbenic form of nitrile imines in the same way they stabilize "normal" singlet carbenes, including N-heterocyclic carbenes. NBO analyses at the CCSD(T) level confirm the classification into propargylic, allenic, and carbenic reactivity types. Carbenic nitrile imines are predicted to form azoketenes 21 with CO, to form [2+2] and [2+4] cycloadducts and borane adducts, and to cyclize to 1H-diazirenes of the type 24 in mildly exothermic reactions with activation energies in the range 29-38 kcal/mol. Such reactions will be readily accessible photochemically and thermally, e.g., under the conditions of matrix photolysis and flash vacuum thermolysis

A wind environment and Lorentz factors of tens explain gamma-ray bursts X-ray plateau

Gamma-ray bursts (GRBs) are known to have the most relativistic jets, with initial Lorentz factors in the order of a few hundreds. Many GRBs display an early X-ray light-curve plateau, which was not theoretically expected and therefore puzzled the community for many years. Here, we show that this observed signal is naturally obtained within the classical GRB "fireball" model, provided that the initial Lorentz factor is rather a few tens, and the expansion occurs into a medium-low density "wind". The range of Lorentz factors in GRB jets is thus much wider than previously thought and bridges an observational gap between mildly relativistic jets inferred in active galactic nuclei, to highly relativistic jets deduced in few extreme GRBs. Furthermore, long GRB progenitors are either not Wolf-Rayet stars, or the wind properties during the final stellar evolution phase are different than at earlier times. We discuss several testable predictions of this model.Comment: 61 pages, 24 figures, 9 tables. A final edited version will appear in Nature Communication

External fixation of the thalamic portion of a fractured calcaneus: A new surgical technique

AbstractThe optimal treatment for intra-articular calcaneus fractures remains controversial, despite internal fixation techniques providing good results. The major point of contention is the need to reconstruct the overall morphology versus to restore the anatomy of the subtalar joint perfectly. We will describe a two-stage technique for treating intra-articular calcaneus fractures in which the primary fracture line goes through the thalamic fragment. The first procedure focuses on the overall morphology by restoring the height and length with osteotaxis being accomplished with a medial external fixator. The second procedure consists of internal fixation through a minimally invasive lateral approach to restore the anatomy of the articular facets. Any defects are filled with injectable bone substitute. This novel technique is compared to the complication rates and radiology and anatomy outcomes in published studies. This two-stage surgical technique reduces the length of hospital stays and the number of complications