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| Poisson Caillault, Emilie; Vanhelst, Florentin; Charlet, Bastian; Mahe, Kelig. |
| Age and growth are primordial essential data in stock assessment and management. However, contracting experts for age estimation using calcified pieces costs several million euros annually. Yet, alternative methods exist for fish ageing using the otolith shape (i.e., otolith shape descriptors or Elliptic Fourier Analysis). The goal of this study is to use a new descriptor of the otolith shape with Mojette Transform as an input of k-Nearest Neighbors (k-NN), Random Forest (RF) and Multi-Layer Perceptron (MLP) classifiers. Mojette Transform is the exact discrete Radon transform used in tomographic reconstruction, image watermarking, or video compression. Its mathematical properties allow reducing the information and having enough redundancy to characterize... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00436/54723/56158.pdf |
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| Poisson Caillault, Emilie; Lefebvre, Alain. |
| Marine water quality monitoring and subsequent management require to know when a specific event like harmful algae bloom may occur and which environmental conditions and pressures lead to this event. So, event detection and its dynamic understanding are crucial to adapt strategy. An algorithm is proposed to identify curves mixture and their dynamics features - initiation, duration, peaks and ends of the event. The approach is fully unsupervised, it requires no tuning parameters and is based on Expectation Maximization process to estimate the most robust mixture according to fixed criteria. A complete framework is proposed to deal with a univariate time series with missing data. The approach is applied on Chlorophyll- a series collected weekly since 1989.... |
| Tipo: Text |
Palavras-chave: Time series; Event detection; Expectation-Maximisation; Phenology; Chlorophyll-a; Phaeocystis. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00435/54679/56097.pdf |
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