Portail HAL confremo Archives ouvertes du Moyen-Orient
Not a member yet
3450 research outputs found
Sort by
Membrane Technologies in Wine Industry: An Overview
No full textInternational audienceMembrane processes are increasingly reported for various applications in wine industry such as microfiltration, electrodialysis, and reverse osmosis, but also emerging processes as bipolar electrodialysis and membrane contactor. Membrane-based processes are playing a critical role in the field of separation/purification, clarification, stabilization, concentration, and de-alcoholization of wine products. They begin to be an integral part of the winemaking process. This review will provide an overview of recent developments, applications, and published literature in membrane technologies applied in wine industry
Increase of photovoltaic panels lifespan by monitoring and control
No full textLes rendements de conversion des cellules solaires atteignent en moyenne aujourd’hui 15%. Malgré ces rendements acceptables, il reste un verrou technologique important à lever : l’amélioration de la durée de vie des modules photovoltaïques. On observe en effet au cours de l’utilisation de ces composants dans des conditions climatiques intermittentes : pluie, neige, moisissures, poussières rayons UV, chocs, corrosion etc.... une perte rapide des propriétés optoélectroniques en fonction des conditions d’utilisation. L’objectif de cette thèse est d’essayer d’améliorer la durée de vie des panneaux solaires et d’améliorer la fiabilité des modules en diminuant le taux de dégradation.Notre approche commence par prendre en compte les effets de vieillissement et des défauts des modules photovoltaïques dont la dégradation est liée à la température, humidité, à la lumière Ultra violette, les fissures etc…. Les défauts de fonctionnement sont analysés et étudiés pour comprendre l’effet et l’importance de chaque paramètre dans les différents modes de dégradation afin de développer des modèles de simulation qui tiennent compte des conditions environnementales.Des algorithmes de commande ont été développés pour une utilisation qui évite au mieux les défauts et permet aux modules photovoltaïques de fonctionner dans des conditions optimales pour l’atténuation des dégradations.Conversion efficiency of solar cells is now on average reaching 15%. Despite these acceptable yields, it remains important to raise a technological limitation: the improvement of the life span of photovoltaic modules. Effects are observed during the use of these components in intermittent weather: rain, snow, molds, dust UV rays, shock, corrosion etc... rapid losses of optoelectronic properties depending on the usage conditions. The objective of this thesis is in twofold: -to try to improve the lifespan of solar panels, and -to improve the reliability of the photovoltaic modules by decreasing their degradation rate. Our approach begins by taking into account the effects of aging of photovoltaic modules whose degradation is related to temperature, moisture, Ultra violet light, cracks etc... Faults are analyzed and studied to understand the impact and the importance of each parameter in the different modes of degradation to develop simulation models that take into account external environmental conditions. Control algorithms have been developed for a best utilization avoiding defects and allowing photovoltaic modules to operate in optimal conditions for mitigation of degradation processes
Hardware MIMO Channel Simulator for Cooperative and Heterogeneous 5G Networks with VLC Signals
No full textPart 1: Wireless Technologies and SystemsInternational audienceThis paper presents the design of an 8 × 8 Multiple-Input Multiple-Output (MIMO) hardware simulator for cooperative time-varying propagation channels (based on relays) using heterogeneous systems (LTE-A and 802.11ac) with Visible Light Communications (VLC) signals. The simulator reproduces a desired radio channel scenario and makes it possible to test “on table” different systems. It uses different impulse responses to cover many types of channels by merging TGn models, 3GPP-LTE models, outdoor-to-indoor measurements results and VLC models. An algorithm is introduced to convert the measured impulse responses from 200 MHz sample frequency to 50 MHz to be compatible with LTE-A signals. A specific architecture of the simulator digital block is presented to characterize 5G scenarios. The architecture is designed on a Xilinx Virtex-VII XC7VX690T Field Programmable Gate Array (FPGA). Its accuracy and FPGA occupation are analyzed
Individual and combined effects of the generalist Forficula auricularia and the specialist Episyrphus balteatus on Dysaphis plantaginea - are two predators better than one?
No full textThe interactions between specialist and generalist natural enemies could affect the success of biological pest control, especially in augmentation programmes. The aim of this laboratory study was to quantitate the individual and combined effects of the generalist predator Forficula auricularia L. (Dermaptera: Forficulidae) and the specialist Episyrphus balteatus De Geer (Diptera: Syrphidae) on the population growth of the rosy apple aphid (RAA), Dysaphis plantaginea Passerini (Hemiptera: Aphididae). The experiment was carried out using apple seedlings with five levels of initial RAA infestation. In most cases, both predator species (alone and in combination) were able to reduce RAA densities or to keep them at their initial level. This suppression effect was greater when RAA densities were low and resulted in near-complete mortality of the RAA colony after 4-6 days. Without predators, RAA population size almost doubled within 10 days, whereas with predators, RAA population size was reduced by about 20 (alone) and 50% (in combination). Although RAA numbers in the two-predators treatment were ca. 81% of RAA numbers in the one-predator treatment for pooled numbers across dates and densities, the difference between the two treatments was not significant. Some predator mortality occurred with first and second instars of the syrphid larvae and only at the two lowest initial RAA infestation levels. This mortality may be explained by inadequate food supply, intraguild predation (IGP) (in 13.3% of the possible cases), or both. However, the incidence of IGP under natural conditions could be even less frequent, as both predators were never observed on the same leaf
Impact of Light Field Compression on Refocused and Extended Focus Images
No full textInternational audienceLight Fields capturing all light rays at every point in space and in all directions contain very rich information about the scene. This rich description of the scene enables advanced image creation capabilities, such as re-focusing or extended depth of field from a single capture. But, it yields a very high volume of data which needs compression. This paper studies the impact of Light Fields compression on two key functionalities: refocusing and extended focus. The sub-aperture images forming the Light Field are compressed as a video sequence with HEVC. A focus stack and the scene depth map are computed from the compressed light field and are used to render an image with an extended depth of field (called the extended focus image). It has been first observed that the Light Field could be compressed with a factor up to 700 without significantly affecting the visual quality of both refocused and extended focus images. To further analyze the compression effect, a dedicated quality evaluation method based on contrast and gradient measurements is considered to differentiate the natural geometrical blur from the blur resulting from compression. As a second part of the experiments, it is shown that the texture distortion of the in-focus regions in the focus stacks is the main cause of the quality degradation in the extended focus and that the depth errors do not impact the extended focus quality unless the light field is significantly distorted with a compression ratio of around 2000:
Textural Properties of Acid Milk Gels: Effects of Dairy Protein Powder Rehydration State
No full textInternational audienceIn this study, the effect of dried dairy ingredient rehydration state on the textural properties and microstructure of acid milk gels was investigated. The control acid gel samples were made with 12% w/w of reconstituted skim milk powder. Milk base was enriched with whey protein isolates and/or micellar casein powders. Different rehydration times (5, 120, 240, 1,440 min) were considered before studying gel textural properties. This study showed that acid milk gels made with whey instead of casein resulted in an increase in firmness, gel strength, graininess but a decrease in syneresis susceptibility. Nevertheless, rehydration duration of casein powder in contrast to that of whey powder strongly altered the physical properties of the obtained acid milk gels. Moreover, prolonged hydration resulted in enhanced textural properties and decreased syneresis. PRACTICAL APPLICATIONS Commercial preparation of yogurt involves different processing steps. Among them, protein fortification of the milk appears as a crucial step that attributes toward the change in textural properties. Milk protein powders are frequently dried in order to stabilize and transport. This is the reason why rehydration is an essential quality attribute of the powder. Consequently, rehydration is often realized by the industry before use and for a long time. This study showed that acid milk gels made with whey instead of casein resulted in an increase in firmness, gel strength, graininess but a decrease in syneresis susceptibility. Rehydration duration of casein powder in contrast to that of whey powder strongly altered the physical properties of the obtained acid milk gels. Prolonged hydration resulted in enhanced textural properties and decreased syneresis. These aspects are of high significance in the preparation of dairy products, i.e., different types of set and stirred yogurts
PME et TIC : de l’appropriation à l’utilisation pour une meilleure performance - Une revue de la littérature
No full textArticle nommé pour le Best Paper Award LCIS(2016)International audienc
Impact of inhibitory peptides released by Saccharomyces cerevisiae BDX on the malolactic fermentation performed by Oenococcus oeni Vitilactic F
No full textInternational audienceA previous study has shown that the malolactic fermentation (MLF) was inhibited during sequential fermentations performed with the pair Saccharomyces cerevisiae BDX/Oenococcus oeni Vitilactic F in synthetic grape juices. A yeast peptidic fraction with an apparent MW of 5-10kDa was involved in the inhibition. In the present study, the MLF was also inhibited in Cabernet Sauvignon and Syrah wines. The inhibition due to the peptidic fraction was maintained despite high phenolic contents. Kinetic studies showed that the peptidic fraction was gradually released during the alcoholic fermentation (AF). Its highest anti-MLF effect was reached when isolated from late stages of the AF stationary phase. The peptidic fraction was tested in vitro on cell-free bacterial cytosolic extracts containing the malolactic enzyme in a pH range between 3.5 and 6.7. Results showed that it was able to directly inhibit the malolactic enzyme activity with an increasing inhibitory kinetic correlated to the AF time at which it was collected
FE8R - A Universal Method for Face Expression Recognition
No full textPart 9: Biometrics, Identification, SecurityInternational audienceThis paper proposes a new method for recognition of face expressions, called FE8R. We studied 6 standard expressions: anger, disgust, fear, happiness, sadness, surprise, and additional two: cry and natural. For experimental evaluation samples from MUG Facial Expression Database and color FERET Database were taken, with addition of cry expression. The proposed method is based on the extraction of characteristic objects from images by gradient transformation depending on the coordinates of the minimum and maximum points in each object on the face area. The gradient is ranked in degrees. Essential objects are studied in two ways: the first way incorporates slant tracking, the second is based on feature encoding using BPCC algorithm with classification by Backpropagation Artificial Neural Networks. The achieved classification rates have reached 95 %. The second method is proved to be fast and producing satisfactory results, as compared to other approaches
Mediterranean Neighbourhood: The Key Triptych Energy-Water-Agriculture
No full textInternational audienceAlong with political unrest since the Arab spring, the stakes of the Mediterranean neighbourhood are numerous: social booming disparities, gender gap, numeric illiteracy, critical case of water supply and agricultural land, difficult decentralisation and state de-concentration. But opportunities are still wider: the Mediterranean is the only neighbourhood whose population and GDP's world share is growing; the rent economy is (slowly) shifting towards a more productive economy with a rising role of clusters; huge investment needs mean huge opportunities for European investors. Secondly, the chapter assesses the trends in economic regional integration (``regionalisation''), showing that the Euro-Mediterranean missing link remains the productive integration. It estimates the importance of the European aid and the normative convergence of norms and standards between the two sides of the Mediterranean (``regionalism''). Its strategic recommendations stress four needs: (i) a common water policy so as to avoid water wars; a food security and agricultural policy; a Euro-Mediterranean Energy Community; turning the ``migration'' vision to a ``mobility'' strategy. In the very difficult transition of Arab neighbours, time calls for a political boldness in Euromed cooperation