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Geodetic instrumentation to validate altimetry sea-level measurements in the Noumea Lagoon – New results from the GEOCEAN-NC 2019 campaign
No full textInternational audienceThe Lagoon surrounding New Caledonia is a site of high interest for satellite altimetry, both for classical nadir missions and for the new SWOT wide swath mission, with dedicated calibration/validation (Cal/Val) experiments planned in 2023 during its 1-D repeat orbit. This poster provides updated results from the 3-weeks campaign GEOCEAN-NC 2019, where various geodetic sea-level observing systems were deployed in the Lagoon (e.g. GNSS Buoy, pressure sensor, CalNaGeo GNSS towed carpet). By combining these data, we reconstruct the dynamics of the lagoon at a point of interest where 3 altimetric tracks intersect (i.e. 1 Jason and 2 Sentinel-3a tracks), and then virtually transfer the Noumea tide gauge records at this particular location. With this approach, we reconstruct two long sea-level time series (i.e. in-situ and altimetry) in the heart of the Lagoon, enabling us to compute altimetry biases and inter-mission biases comparable to those of historical Cal/Val sites for the whole Jason 1/2/3 period and for Sentinel-3a. This update of our results allows us to extend the comparison with new data from year 2022, and consolidate the vertical reference frame used to link our sensors. It is also an opportunity to try to reconcile sea-level rise trends with vertical land movements of permanent GNSS stations, which remains an issue in this area
A review of classical and learning based approaches in task and motion planning
No full textInternational audienceRobots are widely used in many tedious and simple works. But, with the advance of technology, they are expected to work in more complex environments and participate in more challenging tasks. Correspondingly, more intelligent and robust algorithms are required. As a domain having been explored for decades, task and motion planning (TAMP) methods have been applied in various applications and have achieved important results, while still being developed, particularly through the integration of more machine learning approaches. This paper summarizes the development of TAMP, presenting its background, popular methods, application environment, and limitations. In particularly, it compares different simulation environments and points out their advantages and disadvantages. Besides, the existing methods are categorized by their contribution and applications, intending to draw a clear picture for beginners
Synthesis of naphtholactams and their biological evaluation against Pseudomonas aeruginosa
No full textInternational audienceThe naphtholactam scaffold can be found in a lot of natural products or bioactive compounds, with some previous reports highlighting its antibacterial properties. In this context, we report the synthesis of a library of naphtholactams bearing various functional groups and their biological evaluation against the bacterium Pseudomonas aeruginosa. Their synthesis was accomplished through a concise three-step process, from readily available naphthaldehydes, involving a palladium-catalyzed C8-bromination followed by an oxidation/lactam formation sequence
Some Aspects of α-(Acyloxy)alkyl Radicals in Organic Synthesis
No full textInternational audienceThe preparation and use of α-(acyloxy)alkyl xanthates to generate and capture α-(acyloxy)alkyl radicals is briefly reviewed. Their inter- and intramolecular additions to both activated and unactivated, electronically unbiased, alkenes, and to (hetero)aromatic rings, as well as their radical allylation and vinylation reactions are described. Application to the total synthesis of two 4-hydroxytetralone natural products is also presented
Energy Efficient Any-Time I/O Adaptive K-means
No full textInternational audienceDeadline-constrained ML limits in Edge devices Edge Intelligence (EI) : paradigm that brings intelligent applications closer to data collection devices
GrIOt: Graph-based Modeling of HPC Application I/O Call Stacks for Predictive Prefetch
No full textInternational audienceModern High Performance Computing (HPC) storage systems use heterogeneous storage technologies organized in tiers to find a compromise between capacity, performance, and cost. In these systems, prefetching is a common technique used to move the right data at the right moment from a slow to a fast tier to improve the overall performance while using the costly high-performance tier only when needed. Effective prefetching requires precise knowledge of the application I/O patterns. This knowledge can be extracted through the source code, I/O tracing tools or I/O functions call stacks. State-of-the-art solutions based on the latter approach mainly focus on applications with regular I/O profiles to avoid scalability issues due to the grammar-based techniques used. In this paper, we present an approach based on I/O call stacks that models I/O patterns for both regular and irregular applications, thanks to the use of directed graphs. We present different models for prefetching. Our models were used to predict the next I/O call stack on two real HPC applications and one synthetic workload with an accuracy of up to 98%, while keeping a low overheadt
Tandem InCl3-Promoted Hydroperoxide Rearrangements and Nucleophilic Additions: A Straightforward Entry to Benzoxacycles
No full textInternational audienceThe acid-catalyzed rearrangement of organic peroxides is generally associated with C–C-bond cleavages (Hock and Criegee rearrangements), with the concomitant formation of an oxocarbenium intermediate. This article describes the tandem process between a Hock or Criegee oxidative cleavage and a nucleophilic addition onto the oxocarbenium species (in particular a Hosomi–Sakurai-type allylation), under InCl3 catalysis. It was applied to the synthesis of 2-substituted benzoxacycles (chromanes and benzoxepanes), including a synthesis of the 2-(aminomethyl)chromane part of sarizotan, and a total synthesis of erythrococcamide B
A Versatile Route to Acyl (MIDA)Boronates
No full textInternational audienceA modular approach to highly functional acyl (MIDA)boronates is described. It involves the generation of the hitherto unknown radical derived from acetyl (MIDA)boronate and its capture by various alkenes, including electronically unbiased, unactivated alkenes. In contrast to the anion of acetyl (MIDA)boronate, which has not so far been employed in synthesis, the corresponding radical is well behaved and readily produced from the novel α‐xanthyl acetyl (MIDA)boronate. This shelf‐stable, easily prepared solid is a convenient acyl (MIDA)boronate transfer agent that provides a direct entry to numerous otherwise inaccessible structures, including latent 1,4‐dicarbonyl derivatives that can be transformed into B(MIDA) substituted pyrroles and furans. A competition experiment indicated the acyl (MIDA)boronate substituted radical to be more stable than the all‐carbon acetonyl radical but somewhat less reactive in additions to alkenes
Homogenization of thin-structured surfaces for acoustics in the presence of a two-dimensional low Mach potential flow
No full textInternational audienceA surface homogenization method for acoustic waves over thin microstructured surfaces in the presence of a fluid in a potential flow is presented. Sound hard surfaces are considered, the flow is considered two-dimensional and slow and a low Mach approximation is introduced. We consider acoustic waves with a typical wavelength 1 / k much larger than the array spacing h and thickness e . Owing to the small parameter ε = k h , with e / h = O ( 1 ) , a matched asymptotic expansion technique is applied to the low Mach potential wave equation in the frequency domain. A boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). The accuracy of the effective model is tested numerically for various periodic shapes and the accuracy of the model in O ( ε 2 ) is validated