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Spectral Properties of an Energy-Dependent Hamiltonian

Communications in Mathematical Research 2021年第2期37卷 141-179页

作者： pierre chau huu-tai Bernard Ducomet CEA DAMDIFF-91297 ArpajonFrance.2 Universite Paris-EstLAMA(UMR 805)UPEMLVUPECCNRS61 Avenue du General de GaulleF-94010 CreteilFrance

We study spectral properties of a quantum Hamiltonian with a complex-valued energy-dependent potential related to a model introduced in physics of nuclear reactions[30]and we prove that the principle of limiting absorption holds at any point of a large subset of the essential *** an additional dissipative or smallness hypothesis is assumed on the potential,we show that the principle of limiting absorption holds at any point of the essential spectrum.

关键词： Non-selfadjoint complex potentia dissipative limiting absorption principle spectral singularity energy dependent potential

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Estimating Compositions and Nutritional Values of Seed Mixes Based on Vision Transformers

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Plant Phenomics 2023年第4期5卷 805-815页

作者： Shamprikta Mehreen Hervé Goëau pierre Bonnet Sophie chau Julien Champ Alexis Joly Inria LIRMMUniversity MontpellierCNRSMontpellierFrance CIRAD UMR AMAPMontpellierOccitanieFrance Chambre d'Agriculture-Haute Vienne LimogesNouvelle-AquitaineFrance

The cultivation of seed mixtures for local pastures is a traditional mixed cropping technique of cereals and legumes for producing,at a low production cost,a balanced animal feed in energy and protein in livestock *** considerably improving the autonomy and safety of agricultural systems,as well as reducing their impact on the environment,it is a type of crop that responds favorably to both the evolution of the European regulations on the use of phytosanitary products and the expectations of consumers who wish to increase their consumption of organic ***,farmers find it difficult to adopt it because cereals and legumes do not ripen synchronously and the harvested seeds are heterogeneous,making it more difficult to assess their nutritional *** efforts therefore remain to be made to acquire and aggregate technical and economical references to evaluate to what extent the cultivation of seed mixtures could positively contribute to securing and reducing the costs of herd *** work presented in this paper proposes new Artificial Intelligence techniques that could be transferred to an online or smartphone application to automatically estimate the nutritional value of harvested seed mixes to help farmers better manage the yield and thus engage them to promote and contribute to a better knowledge of this type of *** this purpose,an original open image dataset has been built containing 4,749 images of seed mixes,covering 11 seed varieties,with which 2 types of recent deep learning models have been *** results highlight the potential of this method and show that the best-performing model is a recent state-of-the-art vision transformer pre-trained with self-supervision(Bidirectional Encoder representation from Image Transformer).It allows an estimation of the nutritional value of seed mixtures with a coefficient of determination R^(2)score of 0.91,which demonstrates the interest of this type of approach,for its possible use

关键词： transferred cultivation harvest

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A kinetic model for a single step biodiesel production from a high free fatty acid (FFA) biodiesel feedstock over a solid heteropolyacid catalyst

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Green Energy & Environment 2019年第3期4卷 328-341页

作者： Aashish Gaurav Stéphane Dumas chau T.Q.Mai Flora T.T.Ng Department of Chemical Engineering University of Waterloo

Production of biodiesel from yellow grease(waste cooking oil and waste animal fats) is fast emerging as a promising alternative to address the twin challenges before the biodiesel industry today-fluctuation in prices of vegetable oil and the food versus fuel debate. Yellow grease has a high percentage of free fatty acids(FFA) and proves to be an unsuitable feedstock for biodiesel production from commercially viable alkalicatalyzed production systems due to saponification problems.'Green' methodologies based on heterogeneous solid acid catalyzed reactions have the potential to simultaneously promote esterification and transesterification reactions of yellow grease to produce biodiesel without soap formation and offer easy catalyst separation without generation of toxic streams. This paper presents kinetic studies for the conversion of model yellow grease feeds to biodiesel using a heteropolyacid supported on alumina(HSiW/Al2O3) using a batch autoclave. Three model yellow grease feeds were prepared using canola oil with added FFA such as palmitic, oleic and linoleic acid. A pseudo homogeneous kinetic model for the parallel esterification and transesterification was developed. The rate constants and activation parameters for esterification and transesterification reactions for the model yellow grease feeds were determined. The rate constants for esterification are higher than the transesterification rate constants. The kinetic model was validated using the experimental biodiesel data obtained from processing a commercial yellow grease feed. The kinetic model could be used to design novel processes to convert various low-value waste oils, fats and non-food grade oils to sustainable biodiesel.

关键词： Yellow grease Canola oil Free fatty acids Heteropolyacid Kinetics for esterification and transesterification

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