137 research outputs found

    Evaluation of the resistance of few citrus rootstocks to alkalinity by applying a faste test of secreening

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    Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO(3)/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials

    Determination of residence time distribution and axial dispersion coefficient in a meso-scale oscillatory baffled crystallizer using a computational fluid dynamics approach [Abstract]

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    Determination of residence time distribution and axial dispersion coefficient in a meso-scale oscillatory baffled crystallizer using a computational fluid dynamics approach [Abstract

    Utilisation Des Caractères Biochimiques, Agronomiques Et Morphologiques Pour L’évaluation De La Diversité Génétique Des Variants D’orangers Dans La Région Du Gharb, Maroc

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    20 clones of orange trees, identified at the level of the collection of nucellar citrus varieties, have been the subject of several tests of behavior at the level of different citrus fruit sites in Morocco. Indeed, the present work aims to evaluate these variants on a clay soil at the Gharb region (INRA/Kenitra). The variants grafted on Citrange troyer were divided into three groups. Each group contains variants, genetically similar, from seedlings of the same parent variety. Clonal selection is based on the synthesis of the results of the study of the variability of the criteria of fruit quality and production. The average yield varies from 44.25 kg / tree to 217.30 kg / tree. While the average weight of a fruit varies from 95 g to 360 g. The results showed a predominance of juicy and medium-sized fruits with an equatorial diameter greater than 56 mm, acceptable for the fresh fruit market or the juice industry. The maturity coefficient study of the variants within each group, or between the three groups, showed that the harvest period extends over four months, from December to March. The final selection was focused on six productive and good quality variants. These promising variants have been described according to UPOV, and then presented for registration in the official catalog

    Physical Activity Recognition Based on a Parallel Approach for an Ensemble of Machine Learning and Deep Learning Classifiers

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    Human activity recognition (HAR) by wearable sensor devices embedded in the Internet of things (IOT) can play a significant role in remote health monitoring and emergency notification, to provide healthcare of higher standards. The purpose of this study is to investigate a human activity recognition method of accrued decision accuracy and speed of execution to be applicable in healthcare. This method classifies wearable sensor acceleration time series data of human movement using efficient classifier combination of feature engineering-based and feature learning-based data representation. Leave-one-subject-out cross-validation of the method with data acquired from 44 subjects wearing a single waist-worn accelerometer on a smart textile, and engaged in a variety of 10 activities, yields an average recognition rate of 90%, performing significantly better than individual classifiers. The method easily accommodates functional and computational parallelization to bring execution time significantly down

    Mechanical behavior and optimization of multidirectional laminate specimens under delamination by bending

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    Delamination in the multidirectional laminates under bending loading is often difficult to characterize because of problems involved by excessive deformations ahead of the crack tip and by non-linearities due to large displacements and transverse microcracking. In fact, these microcracks appear in the most strained plies especially for thin materials. Consequently, the concept of linear elastic fracture mechanic cannot be used in order to characterize delamination. Thus, the objective of this work is to highlight, experimentally and analytically these problems on DCB specimens, then to carry out optimization of thickness which makes it possible to avoid the appearance of transverse cracking before starting of delamination. The material used is E-glass/epoxy multidirectional laminates. The results of optimization obtained are in good agreement with the experimental results.При навантаженні згином багатовимірних ламінатів має місце деламінація. Її опис є досить важким, оскільки у вістрі тріщини присутні великі деформації та відмічаються нелінійні ефекти, що зумовлені значними переміщеннями і утворенням поперечних мікротріщин. Останні з’являються у найбільш навантажених шарах, особливо в тонких ламінатах. Експериментально досліджено вищезгадані особливості на зразках у вигляді консольної балки та виконано оптимізацію товщини багатошарового зразка, за якої деламінація починаєтьсядо утворення поперечних мікротріщин у найбільш навантажених шарах. Об’єктом дослідження служив склоепоксидний зміцнений ламінат. Отримані результати оптимізації товщини зразка добре узгоджуються з експериментальними даними.При изгибном нагружении многомерных ламинатов имеет место деламинация, описание которой весьма затруднительно ввиду наличия больших деформаций у вершины трещины и различных нелинейных эффектов, связанных со значительными перемещениями и образованием поперечных микротрещин. Последние появляются в наиболее нагруженных слоях, особенно в тонких ламинатах. Экспериментально исследованы вышеуказанные особенности на образцах в виде консольной балки и выполнена оптимизация толщины многослойного образца, при которой деламинация начинается до образования поперечных микротрещин в наиболее нагруженных слоях. Объектом исследования служил стеклоэпоксидный упрочненный ламинат. Полученные результаты оптимизации толщины образцов хорошо согласуются с экспериментальными данными

    Nitrogen-rich hyper-crosslinked polymers for low-pressure CO2 capture

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    A series of poly[methacrylamide-co-(ethylene glycol dimethacrylate)] (poly(MAAM-co-EGDMA)) porous polymeric particles with high CO2-philicity, referred to as HCP-MAAMs, were synthesised for CO2 capture. The polymers with a MAAM-to-EGDMA molar ratio from 0.3 to 0.9 were inherently nitrogen-enriched and exhibited a high affinity towards selective CO2 capture at low pressures. A techno-economic model based on a 580 MWel supercritical coal-fired power plant scenario was developed to evaluate the performance of the synthesised adsorbents. The presence and density of NH2 moieties within the polymer network were determined using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The thermogravimetric analysis (TGA) showed that the polymers were thermally stable up to 515–532 K. The maximum CO2 adsorption capacity at 273 K was 1.56 mmol/g and the isosteric heat of adsorption was 28–35 kJ/mol. An increase in the density of amide groups within the polymer network resulted in a higher affinity towards CO2 at low pressure. At a CO2:N2 ratio of 15:85, CO2/N2 selectivity at 273 K was 52 at 1 bar and reached 104 at ultra-low CO2 partial pressure. The techno-economic analysis revealed that retrofitting a HCP-MAAM-based CO2 capture system led to a net energy penalty of 7.7–8.0%HHV points, which was noticeably lower than that reported for MEA or chilled ammonia scrubbing capture systems. The specific heat requirement was superior to the majority of conventional solvents such as MDEA-PZ and K2CO3. Importantly, the economic performance of the HCP-MAAM retrofit scenario was found to be competitive to chemical solvent scrubbing scenarios
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