HAL Collection UNC (Univ. de la Nouvelle Calédonie)
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Graveurs sur nacre. L'art des forçats de Nouvelle-Calédonie
No full textInternational audienceAu bagne de Nouvelle-Calédonie, entre les années 1870 et 1930, les condamnés et l’administration pénitentiaire ont organisé, comme à Toulon ou en Guyane, une activité artisanale et artistique : le « camelotage ». La vente d'objets fabriqués, le plus souvent des coquillages polis, sculptés et gravés, permettait à ces hommes perdus dans les ténèbres du bagne d’améliorer un quotidien difficilement supportable. Au sein de cette production parfois naïve, souvent touchante, toujours ingénieuse, se trouvent des pièces d'une grande virtuosité. Elles sont ici décryptées grâce au fonds constitué par les musées de la ville de Nouméa et des collectionneurs privés. Ces forçats artistes, dont certaines des trajectoires peuvent être reconstituées, ont su trouver de l'inspiration dans leur foi et leurs souvenirs de France comme dans les paysages océaniens et le peuple kanak
Making the Best Use of High-Resolution Meteorological Forecasts for Flash Flood Forecasting Using ANN: Case Study on the Gardon de Mialet Basin
No full textInternational audienceIn Mediterranean regions, the difficulty of measuring and forecasting rainfall intensity, as well as the difficulty of identifying flood-generating processes, often lead to the use of statistical models, like neural networks. However, without the coupling with meteorological forecasts, current hydrological models are most often limited to a lead time equivalent to the response time of the basin, i.e. a few hours for small basins. The challenge is to increase this lead time, which is often too short for crisis management. As support for demonstration, a flood forecasting model for the Gardon de Mialet basin (Southern France) has been developed. The neural network model implemented (a Multilayer Perceptron) has been fed with the AROME high resolution model to produce forecasts with lead times of up to 24 hours, compared with 2 to 3 hours previously. The use of raw data predicted by AROME for the 47 rainfall events in the database produced flow results which were used as a basis for improvement. We therefore began by identifying the sources of forecast error (meteorological or hydrological models, or both models together), and then qualifying and quantifying meteorological forecast errors. At the end of this process, an approach is proposed for making an optimal use of weather forecasts from AROME, taking into account errors in synchronization, location and intensity of the rainfall
Strategic Pasts and Precarious Futures: Rethinking the Indo-Pacific in the Present
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Evaluation of Modular Polynomials from Supersingular Elliptic Curves
No full textInternational audienceWe present several new algorithms to evaluate modular polynomials of level ℓ modulo a prime p on an input j. More precisely, we introduce two new generic algorithms, sharing the following similarities: they are based on a CRT approach; they make use of supersingular curves and the Deuring correspondence; and, their memory requirements are optimal.The first algorithm combines the ideas behind a hybrid algorithm of Sutherland in 2013 with a recent algorithm to compute modular polynomials using supersingular curves introduced in 2023 by Leroux. The complexity (holding around several plausible heuristic assumptions) of the resulting algorithm matches the Õ(ℓ 3 log 3 ℓ + ℓ log p) time complexity of the best known algorithm by Sutherland, but has an optimal memory requirement.Our second algorithm is based on a sub-algorithm that can evaluate modular polynomials efficiently on supersingular j-invariants defined over Fp, and achieves heuristic complexity quadratic in both ℓ and log j, and linear in log p. In particular, it is the first generic algorithm with optimal memory requirement to obtain a quadratic complexity in ℓ.Additionally, we show how to adapt our method to the computation of other types of modular polynomials such as the one stemming from Weber's function.Finally, we provide an optimised implementation of the two algorithms detailed in this paper, though we emphasise that various modules in our codebase may find applications outside their use in this paper.</div
Digital NGD Design for FPGA-based Application
No full textInternational audienceNegative Group Delay (NGD) remains a little-known concept in embedded digital signal processing, and most electronic designers are unfamiliar with its design and analysis. This paper presents a clear, step-by-step theoretical framework and a practical methodology for implementing baseband NGD using a low-order finite impulse response (FIR) filter. All FIRbased NGD parameters and characteristics can be defined under specific conditions based solely on the desired NGD value and the sampling frequency. Our synthesis results confirm that the realized time-advance increases with normalized frequency. We validate the approach through simulation and then demonstrate a proof-of-concept FPGA implementation. In transient experiments using a 3 kHz Gaussian pulse, the NGD circuit produces an advance of approximately 13 µs relative to the input signal and the NGD execution time is about 2µs
Supporting information files to: Provenance reassessment of Eocene turbidites, New Caledonia: Inferences for obduction models.
No full textInternational audienceThis archive contains the supporting information files to an article published in G cubed. The files consist of one word document and five excel spreadsheets. Supporting information.docx (material and methods, analytical procedures; field images, additional figures and microphotographs) Table S2: LA-ICP-MS trace element geochemical data of clinopyroxenes Table S3: whole-rock major and trace element data on clasts of breccia/olistostrome Table S4: U-Pb data of micro-zircons from dolerite clast samples Table S5: U-Pb data of detrital zircons from Bourail and Nepoui-Koumac flysches Table S6: microprobe analyses of clinopyroxenes of selected samples from Poya Terrane basalts (Parat 1995
