Save and Transmit Scheme for Energy Harvesting MIMO Systems with TAS/MRC

In this paper, we propose and analyze a wirelesstransmitter, for multiple-input multiple-output (MIMO) systems,that relies exclusively on energy harvesting. We consider wirelesstransceivers where the transmitter harvests the total requiredenergy from its environment through various sources. We assumethat both transmitter and receiver are equipped with multipleantennas. At the transmitter, a single transmit antenna thatmaximizes the signal-to-noise ratio (SNR) at the receiver isselected for transmission. The remaining antennas are used forenergy harvesting. At the receiver side, maximal-ratio com-bining (MRC) is used. Furthermore, we assume that all theharvested power is used to power the transmitter immediately.The performance of the proposed scheme is analyzed in terms ofoutage probability (OP), symbol error rate (SER) and channelcapacity. The harvested energy comes from random sourcesand is considered as a random variable. Assuming that theharvested power follows a gamma distribution and the MIMOchannel is a Rayleigh flat fading process, we derive a closed-form expressions for the exact cumulative distribution function(CDF) and probability density function (PDF) of the SNR. Basedon this, we analyze the performance of the proposed energyharvesting scheme. The obtained analytical results are validatedby comparing them with the results of Monte-Carlo simulations

Save and Transmit Scheme for Energy Harvesting MIMO Systems with TAS/MRC

In this paper, we propose and analyze a wireless transmitter, for multiple-input multiple-output (MIMO) systems,that relies exclusively on energy harvesting. We consider wireless transceivers where the transmitter harvests the total required energy from its environment through various sources. We assume that both transmitter and receiver are equipped with multiple antennas. At the transmitter, a single transmit antenna that maximizes the signal-to-noise ratio (SNR) at the receiver is selected for transmission. The remaining antennas are used for energy harvesting. At the receiver side, maximal-ratio com-bining (MRC) is used. Furthermore, we assume that all the harvested power is used to power the transmitter immediately.The performance of the proposed scheme is analyzed in terms of outage probability (OP), symbol error rate (SER) and channel capacity. The harvested energy comes from random sources and is considered as a random variable. Assuming that the harvested power follows a gamma distribution and the MIMO channel is a Rayleigh flat fading process, we derive a closed-form expressions for the exact cumulative distribution function(CDF) and probability density function (PDF) of the SNR. Based on this, we analyze the performance of the proposed energy harvesting scheme. The obtained analytical results are validated by comparing them with the results of Monte-Carlo simulations

A highly osmotolerant rhizobial strain confers a better tolerance of nitrogen fixation and enhances protective activities to nodules of Phaseolus vulgaris under drought stress

The effect of water deficiency on nodules of common bean (Phaseolus vulgaris) inoculated with three rhizobial strains differing in their osmotolerance, was investigated in two different experiments on sterile sand. In the first experiment, the control plants were maintained at 90% field capacity (FC) and water-deficient plants were grown at 35% FC. The nitrogen fixation and growth parameters drastically decreased under water deficiency, however the three rhizobial strains, Rhizobium etli A32 (sensitive), Rhizobium tropici CIAT899 (tolerant), and Ensifer meliloti 4H41 (highly tolerant), showed different symbiotic performances. E. meliloti 4H41 allowed the best acetylene reduction activity (ARA) and biomass production and the highest number of large-sized nodules, while no significant effect was observed on lipid peroxidation, protein and legheamoglobin contents. The effect on antioxidant activities was the lowest. In the second experiment, plants were maintained at 90% FC during 45 days and then watering was stopped. The results showed that, the response to water deficit was quite similar for the three analyzed symbioses until 35% FC, but below this value of FC, symbiosis involving strain E. meliloti 4H41 was the most tolerant. This tolerance was accompanied, by in both experiments, by a stability of metabolic indices and protective antioxidant activities. These results suggest that, the relative tolerance of the nodules induced by strain 4H41 could be due to a constructive adaptation involving specific cortex structure and stress-adapted metabolic activities acquired during nodule formation and growth, rather than to a timely inducible response due to the stimulation of antioxidant enzymes. This suggestion should be confirmed through microscopic structure analysis and supplemental key enzymes in nodule metabolism such as sucrose synthase and malate dehydrogenase.Key words: Antioxidant activities, in pots experiment, leghemoglobin content, nodule, rhizobia, osmotolerance, symbiotic efficiency, water deficiency

No-wait scheduling of a two-machine flow-shop to minimize the makespan under non-availability constraints and different release dates

International audienceIn this paper, we consider the two-machine no-wait flow-shop scheduling problem, when every machine is subject to one non-availability constraint and jobs have different release dates. The non-availability intervals of the machines overlap and they are known in advance. We aim to find a non-resumable schedule that minimises the makespan. We propose several lower bounds and upper bounds. These bounding procedures are used in a branch-and-bound algorithm. Computational experiments are carried out on a large set of instances and the obtained results show the effectiveness of our method

La transgression albienne dans la région de Tajerouine en Tunisie Centrale : Stratigraphie, sédimentologie et tectonique synsédimentaire

During Lower Cretaceous, Central Tunisia belonged to the South-Téthyan passive margin. Paleogeographically, it was marked by the transition between the stable Saharian platform to the South, and the open marine Tethyan basin to the North. Our study deals with the evolution of this transition zone (El Kef-Tajerouine area) during the Albian transgression, which is represented by the Hameïma and Fahdène formations that overly the Aptian Carbonate shelf. Exhaustive ammonite collections allowed defining a regional biozonation, to establish the earliest Albian age of the Hameïma Fm, to evidence a sedimentary hiatus of most of the Middle Albian, and to state the diachronism of the Late Albian transgression. Detailed study of facies and biotic assemblages led to recognise the environmental evolutions, to identify discontinuities, to define sequences and to correlate them throughout the studied area, thanks to the biostratigraphy. The studied succession can be divided into five third-order depositional sequences. The first two sequences (SA1, SA2) correspond to mixed, clastic-carbonate, shelf deposits, and are separated from each other by karstified exposure surfaces. They can be subdivided into minor depositional sequences that can be correlated regionally. The three overlying sequences (SA3 to SA5) were deposited in basinal environments. Above submarine erosional surfaces (sequence boundaries), are carbonated Lowstand systems tracts with benthic faunas, which are overlain by dark shales, whithin which the Maximum flooding surface is locally marked by pyritous or phosphatic ammonites. Particular surfaces (sequence or parasequence boundaries, maximum flooding or transgressive surfaces) are characterized by positive or negative excursions of the 18O and 13C stable isotope curves. At that time, Central Tunisia was a gently Northward-dipping ramp, submitted to very low energy deposition, although moderate shelf currents were active. The Albian transgressions provoked the drowning of the Aptian and earliest Albian platforms, and the South or SE-ward backstepping of the shelf facies. Tectonic synsedimentary deformations began around the Aptian-Albian boundary, and increased in number, extent and intensity throughout the Early Albian, before to culminate with the Middle Albian sedimentary hiatus. These deformations were probably the cause of halocinetic deformations, since they usually predate diapir uplift. This tectonic unstability would be related to the end of the South Atlantic Ocean opening, the rifting of which seems to propagate between the African Saharian and Ethiopian shields, before to eventually break up toward the Central Atlantic Ocean.Durant le Crétacé inférieur, le paysage paléogéographique de la Tunisie était représenté par les domaines suivants : une plate-forme stable continentale au sud, un bassin marin ouvert sur le sud de la Téthys au nord et une zone de transition entre les deux domaines sud et nord, représentée par une plate-forme carbonatée à mixte et des hauts-fonds. Dans notre étude, nous nous sommes intéressé à cette zone de transition (secteur d'el Kef-Tadjerouine) qui montre une évolution d'un milieu néritique à un milieu plus ouvert. Dans les successions étudiées des secteurs du Slata, Djerissa, Boulahnèche et Hameïma, deux formations lithologiques déjà établies par des travaux antérieurs ont été étudiées, la Formation Hameïma et la Formation Fahdène. Dans ces successions, la découverte d'ammonites contribue à une nouvelle définition régionale des zones et à la découverte d'un Albien inférieur très étendu et plus complet par rapport à d'autres endroits. Avec l'aide de cette biozonation, d'une étude fine de faciès et d'assemblages faunistiques, d'une reconnaissance des environnements de dépôt, d'une hiérarchisation des surfaces et des séquences, des corrélations stratigraphiques sont établies entre les différentes coupes. Ces corrélations permettent de délimiter des séquences et de proposer une reconstitution paléogéographique de la zone d'étude. L'analyse séquentielle a permis de découper l'intervalle étudié en cinq séquences de troisième ordre. Ainsi, dans la plate-forme silico-carbonatée, deux séquences d'ordre trois ont été identifiées (SA1 et SA2). Elles sont séparées par des surfaces d'exposition subaérienne matérialisées par des karsts. Ces deux séquences SA1 et SA2 ont été découpées en séquences d'ordre inférieur qui ont été corrélées entre les différents secteurs. Les trois autres séquences ont été identifiées dans le bassin (SA3, SA4 et SA5) et ont été également corrélées entre les différentes coupes. Le passage entre les séquences de plate-forme et séquences de bassin a été marqué par l'ennoyage de la plate-forme dans le cadre de la transgression albienne. La tectonique locale a joué un rôle primordial dans l'organisation paléogéographique, en effet, les cortèges sédimentaires peuvent présenter des variations en allant d'un secteur à autre. Finalement, l'étude séquentielle a été appuyée par une étude des variations des isotopes stables de l'oxygène 18 et du carbone 13. En effet, les courbes des variations de ces deux isotopes semblent avoir enregistré des anomalies qui coïncident avec les surfaces particulières telles que les limites de séquences, de paraséquences, les surfaces d'inondation et les surfaces de transgression

Système d'identification de personnes basé sur la rétine

Our work is part of the retina biometrics. The retina is the sensory layer of the eye; it has a rich and unique texture even in twins. Its properties have made the retina biometrics an active research area. Indeed, numerous methods have been proposed for the various stages of the biometric method, from pretreatment of the retinal image to its analysis, through its characterization, in order to identify and authenticate an individual. We are interested in this work in these thesis works, the study, design, development and evaluation of a new biometric method based on the retina. This thesis presents our contributions for each stage of the proposed biometric method. Our first contribution lies in the proposition of a healthy and pathological retinal image analysis method, followed by a selection of a region of interest around the optical disc. This method improves the quality of the retinal image and extracts a more stable region of interest from the retina to maintain a satisfactory information density, to ensure a better quality of recognition. Our second contribution consists in proposing a new method for extracting local characteristics based on the standard SIFT descriptor. It applies a new method based on the removal of non-informative points of interest extracted by the standard SIFT descriptor. This new method of extracting local features reduces the number of redundant points of interest while maintaining the quality of the description. We validated, the proposed biometric method on different bases including healthy and pathological images. This biometric method has yielded encouraging results on healthy and pathological retinal images. The results obtained show encouraging performances. These results indicate that the method we have proposed, correctly locates the retinal region of interest. In identification mode, a correct identification rate of approximately 99.8% is reached. In verification mode, we obtained 0.12% as FRR error rate and 0% for the FAR and EER error rates. The comparative study showed that our method is more discriminative than other state-of-the-art methods, especially those based on segmentation and extraction of the vascular treeNotre travail s’inscrit dans le cadre de la biométrie par la rétine. La rétine est la couche sensorielle de l’œil, elle présente une texture riche et unique même chez les jumeaux. Ses propriétés ont fait de la biométrie par la rétine un axe de recherche actif. En effet, de nombreuses méthodes ont été proposées pour les différentes étapes de la méthode biométrique allant du prétraitement de l’image rétinienne à son analyse, en passant par sa caractérisation, afin d’identifier et authentifier un individu. Nous nous intéressons dans ces travaux de thèse, à l’étude, la conception, le développement et l’évaluation d’une nouvelle méthode biométrique basée sur la rétine. Notre première contribution réside dans la conception d’une méthode d’analyse d’image rétinienne saine et pathologique, suivie d’une sélection d’une région d’intérêt autour du disque optique. Cette méthode améliore la qualité de l’image rétinienne et extrait une région d’intérêt la plus stable de la rétine afin de maintenir une densité d’information satisfaisante, pour assurer une meilleure qualité de reconnaissance. Notre deuxième contribution porte sur la proposition d’une nouvelle méthode d’extraction de caractéristiques locales basée sur le descripteur standard SIFT. Elle applique une nouvelle approche reposant sur la suppression des points d’intérêt non informatifs extraits par le descripteur standard SIFT. Cette nouvelle méthode d’extraction des caractéristiques locales réduit le nombre des points d’intérêt redondants tout en maintenant la qualité de la description. Nous avons validé, la méthode biométrique proposée sur différentes bases comprenant des images saines et pathologiques. Les résultats obtenus montrent des performances encourageantes. Ces résultats indiquent, que la méthode que nous avons proposée, localise correctement la région d’intérêt rétinienne. En mode identification, un taux d’identification correcte d’environ 99.8% est atteint. En mode vérification, nous avons obtenu un taux FRR de 0.12% quant aux taux FAR et EER (erreur), ils sont de 0%. L’étude comparative a montré que notre méthode est plus discriminative que d’autres méthodes de l’état de l’art, notamment celles basées sur la segmentation et l’extraction de l’arbre vasculair