Дисертації з теми "Modélisation de disponibilité"
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Kanoun, Karama. "Croissance de la sûreté de fonctionnement des logiciels : caractérisation, modélisation, évaluation." Toulouse, INPT, 1989. http://www.theses.fr/1989INPT091H.
Arnaud, Jean. "Performance, disponibilité et coût de services Internet adaptatifs." Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00529936.
Devau, Nicolas. "Processus rhizosphériques déterminant la disponibilité en phosphore : apport de la modélisation mécaniste géochimique." Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0019.
Root-induced chemical processes are recognized as a major strategy developed by plants to enhance phosphorus (P) availability and thus to promote P acquisition. However, the exact influence of these root-induced chemical processes is still poorly understood and quantified. The present study aimed at investigating the influence of root-induced chemical processes, especially root-induced pH changes, on P availability in the rhizosphere. In this work, we used a set of mechanistic adsorption models (« 1-pK triple plane », ion-exchange and Nica-Donnan) within the framework of the component additive approach in order to simulate the effects of root activity on P availability. First, we described the effects of pH on P availability in several soils unaffected by roots, a Chromic Cambisol and a Luvisol. The Luvisol showed different concentrations in inorganic P because of a long-term fertilisation trial. In the rhizosphere of durum wheat (Triticum tu rgidum durum L.) grown on these two soils, we found that calcium (Ca) uptake, in addition to P uptake and root-induced alkalisation, controlled to various extents the changes of soil P availability. Calcium uptake markedly increased P availability by decreasing the promoting effect of Ca adsorption on P adsorption. The relative influence of these three root processes depended on the solution composition (especially concentration of Ca and pH). Our simulations showed the relationship between changes in P availability and the speciation of adsorbed P onto the different soil minerals. Soil mineralogy, especially the relative abundance of illite vs. Fe oxides, controlled the influence of root processes by regulating the contribution of soil minerals to P adsorption. By identifying a novel root-induced processes, namely the Ca uptake, and describing its influence on P availability, our results demonstrate the ability of surface complexation models to predict the effects of root-i nduced processes on P availability in soils
Saintis, Laurent. "Modélisation et évaluation des performances de disponibilité d'un avion dans un contexte opérationnel lors des phases de conception." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/4300/.
This thesis deals with the modelling and computation of in-service aircraft availability at the preliminary design stage. This problem is crucial for designers because it enables them to evaluate availability indicators in order to improve systems under design and to optimize aircraft support. We formalize the dynamic process of technical incidents and their effects on corrective maintenance in airline's aircraft operations. In the context of a mission defined by a sequence of flight cycles, standard reliability methods are not computationally conceivable with respect to industrial timing constraints. Based on analytic developments, we introduce a methodology that provides an efficient algorithm for computing bounds for availability indicators. Finally, we show the usefulness of our approach on use-cases inspired by real-world aircraft systems
Martinello, Magnos. "Modélisation et évaluation de la disponibilité de services mis en oeuvre sur le web : une approche pragmatique." Toulouse, INPT, 2005. https://hal.science/tel-04595476.
This thesis presents a pragmatic modeling approach allowing designers of web-based applications and systems to evaluate the service availability provided to the users. Multiple sources of service unavailability are taken into account, in particular i) hardware and software failures affecting the servers, and ii) performance degradation (overload of servers, very long response time, etc. ). An hierarchical multi-level approach is proposed based on performability modeling, combining Markov chains and queueing models. The main concepts and the feasibility of this approach are illustrated using a web-based travel agency. Various analytical models and sensitivity studies are presented considering different assumptions with respect to the architectures, recovery strategies, faults, users profile and traffic characteristics
Zequeira, Alfonso Romulo Isbel. "Modélisation stochastique pour l'évalusation de politiques d'inspection et de maintenance des systèmes de sécurité." Troyes, 2005. http://www.theses.fr/2005TROY0008.
High safety systems availability is important to keep industrial risks at low levels. Usually the failures of those systems can be detected only by periodic inspections. Besides, they deteriorate in time. Hence to replace them periodically may decrease total cost. We consider the determination of inspection and maintenance policies of safety systems. Important practical aspects considered in this thesis are the quality of inspections, the quality of maintenance actions and the use of predictive maintenance. We study how to include in the models the opportunities for inspecting and replacing the system. Further, we examine the inspection and maintenance policy for two-components parallel systems with dependent component lifetimes, for two criteria: the cost rate and a reliability constraint
EREAU, Jean François. "Réseaux de Petri pour l'étude de la disponibilité opérationnelle des systèmes spatiaux en phases d'avant-projet." Phd thesis, Université Paul Sabatier - Toulouse III, 1997. http://tel.archives-ouvertes.fr/tel-00010089.
Savard, Christophe. "Amélioration de la disponibilité opérationnelle des systèmes de stockage de l'énergie électrique multicellulaires." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI111/document.
High-capacity electrical energy storage system (EESS) are often matrix-organized system with a large number of elementary storage cells. Due to manufactoring tolerances and their individual use, the electrical characteristics of these cells do not evolve in the same way. These imbalances reduce operative dependability, in the short term by contributing to a decrease of the charge-discharge capacity, in the long-term by shortening lifetime. To improve storage performance, redundant cells can be added. It is also possible, in order to increase efficiency of stored energy restitution, to balance electrical characteristics by using energy exchange forced by an adequate configuration. It should therefore be possible to increase long-term operative dependability by reconfiguring internal connections in dynamic mode. Parallel-series (PS) architecture EESS consists of the series association of blocks, made up of several cells connected in parallel. Series-Parallel dual solution (SP) associates strings of cells in parallel. If other architectures are being studied, often requiring several switches per cell to reconfigure the matrix, we propose in this thesis a new architecture, called C3C, satisfying an acceptable level of reliability and distributing current flows. We then compare the classic solutions and the C3C in terms of reliability and the long-term operative dependability and propose a reflection on the possibilities to discrete control aspects to pilot architecture with a suitable control algorithm. The reliability of any structure can be improved by redundancy, with additional cells that will be used either to replace failing cells or temporarily supplemeting the weak ones. The system may also be designed to tolerate the defect of a portion of the cells. We demonstrate by modeling reliability diagrams and Markov chains that the C3C and PS architectures have a much eigher level of reliability than a SP architecture. The sustainability of these structures can also be improved by piloting activating and rest of the available resources according to different strategies in a choice algorithm based on SoC (State of Charge) or SoH (State of Health) of each cell. To do this, we model a cell on Matlab, precisely simulating the aging parameters and their dynamic evolution. It emerges that, whatever the architecture, if it includes a minimal share of redundant cells, an adequate differentiated management of the cells allows an improvement of the long-term operative dependability of nearly 40% on average. In order to study the reconfigurability control of architectures, we propose a model based on Discrete Event Systems through a colored Petri net. Simulation of this model has reinforced the behaviors already identified
Djeridi, Radhouane. "Contribution à la maîtrise de la disponibilité de systèmes complexes : proposition d'une méthode de réordonnancement proactif de la maintenance." Phd thesis, Paris, ENSAM, 2010. http://pastel.archives-ouvertes.fr/pastel-00592437.
Dhouib, Karem. "Modélisation, analyse et amélioration de la disponibilité des systèmes de production cellulaires dont les machines sont sujettes à des défaillances aléatoires." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/NQ43059.pdf.
Brun, François. "Modélisation du fonctionnement de la plante Arabidopsis thaliana dans différents contextes de disponibilité en N du sol : impact sur l'architecture racinaire." Paris 11, 2006. http://www.theses.fr/2006PA112256.
A nitrogen limitation causes important effects on the development and the growth of the plant that presents an adaptative response under such conditions. The plasticity of the root system is an essential element of this response. The objective of this study was to analyze the response of the root system to a nitrogen limitation by trying to take into account the whole plant functioning. We chose a modelling approach to simulate the whole plant functioning in Arabidopsis thaliana with a detailed description of the morphogenetic processes of the root system under contrasted nitrogen conditions. Experiments were carried out under cross conditions carbon and nitrogen nutritions to specify these effects on the root system architecture and to collect data for our modelling approach of the whole plant. Most of our study is on one genotype, the ecotype Wassilewskija (Ws-0), and proposes an analysis framework for future studies on genetic variability
Léger, Jean-Baptiste. "Contribution méthodologique à la maintenance prévisionnelle des systèmes industriels de production : proposition d'un cadre formel de modélisation." Nancy 1, 1999. http://www.theses.fr/1999NAN10114.
Thaler, Philippe. "Relations entre développement racinaire et développement aérien : modélisation de l'influence de la disponibilité en assimilats carbonés sur l'architecture racinaire d'"Hevea brasiliensis"." Montpellier 2, 1996. http://www.theses.fr/1996MON20258.
Meng, Huixing. "Modeling Patterns for Performance Analysis of Production and Safety Systems in Process Industry." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX074/document.
Production and safety systems are crucial in the process industry. Their performances affect significantly the industry interests. These systems have common behaviors. Such behaviors can be captured in models via modeling patterns. By reusing modeling patterns, the modeling process can be simplified and made more efficient.In this thesis, we propose a versatile set of modeling patterns. They are classified according to their purpose, which reflects what a modeling pattern works for. Modeling patterns are exhibited as a catalog. Based on reviewing numerous production and safety systems, twenty-four (24) modeling patterns are introduced. Each pattern is illustrated with a set of structured items. We propose a pattern-based methodology for performance analysis of production and safety systems.To test the applicability of proposed modeling patterns, we conducted experimental studies on a set of production and safety systems. All systems are extracted from the literature. These systems are declared to cover most of modeling difficulties. Comparisons are performed between the results obtained using modeling patterns and those reported in the literature
Brulebois, Etienne. "Impacts du changement climatique sur la disponibilité de la ressource en eau en Bourgogne : aspects quantitatifs et qualitatifs." Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS027/document.
Numerous studies dealing with climate change impacts on water ressources have been done at global scale, but the moderated size watersheds scale is less studied. The Burgundy region is located over several hydrographical basins (Seine, Loire and Rhône river), and provides a great diversity of hydrogeological and climate contexts. For these reasons, impacts of climate change on water resources are expected to be very different in space, and require an entire hydroclimatic modelling chain at local scale to be assessed. The main objective of this thesis consisted of the implementation of a modelling tool at the moderated-size watersheds scale of Burgundy. In this way, several watersheds and two hydrological models have been chosen : a global and empirical rainfall-runoff model (GR4J) and a physical based and semi-spatialised model (SWAT). These two models allow us to assess every aspects of climate change impacts : quantitative (streamflow and spatialised ressource) and qualitative impacts.Models have been calibrated, including a cross calibration/validation test in climate contrasted periods, to confirm their robustness. A disaggregation of global climate data has been done in order to feed models during projection.Observations analysis highlighted a climate shift (in Burgundy as well as over the entire french territory), resulting in a modification of hydrological regime. Models projection over the XXIth century showed i) not much evolution of annual streamflow, but an accented seasonality, with an increase of winter streamflow, and a decrease of summer streamflow, linked with the rainfall regime and the evapotranspiration increase, ii) drought flow indices showing an increase of severity of the drought flow period, iii) a decrease in water quality. In order to explore the capacities of the modelling chain, several sensibility tests have been done, based on management practices scenarios
Huanosto-magaña, Ruth. "Analyse et modélisation de l'utilisation du nitrate en lien avec sa disponibilité et la croissance. Étude de cas chez la tomate (Solanum lycopersicum)." Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00004242.
Huanosto-Magaña, Ruth. "Analyse et modélisation de l'utilisation du nitrate en lien avec sa disponibilité et la croissance : étude de cas chez la tomate (Solanum lycopersicum)." Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0055.
Cherif, Mohamed Amine. "Modélisation dynamique de la (bio)disponibilité des radionucléides dans les sols : approche comparative modèles-expériences appliquée au transfert de césium dans la rhizosphère." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0547/document.
The overall objective of this work is to develop a generic model able to better account and predict the transfer of radionuclides in the soil / soil solution / plant. The first part of the work was devoted to the critical analysis of the models available in the literature to describe the cesium adsorption on clay minerals (the process that mainly controls its availability in the soils). This analysis enabled us to propose a new mechanistic model combining two approaches: surface complexation and cation exchange. Our approach has been tested in order to model the adsorption of Cs on several natural clay substrates, in a wide range of Cs concentrations and physicochemical conditions. This work allowed to validate the proposed mechanistic model and to demonstrate that it constitutes a major advantage over the various existing models. The second part was devoted, to the performing of a series of experiments, carried out in controlled environments on dynamic systems and modeling the (bio)availability of Cs in these systems. Following these tests, the observed interactions between solid and solution could be correctly reproduced with the proposed model taking into account only the clay fraction of the soil. These simulations were also compared with simulations obtained using a empiric (Kd) kinetic models (E-K approach). Finally, the development of a numerical tool for coupling the description of geochemical interactions with transfer to the plant (Michaelis-Menten approach) allowed to reproduce adequately the trials carried out in Rhizotests coupling soil, solution and plant, and to better characterize of the Cs fraction available for plants
Najla, Safaa. "Analyse et modélisation de la croissance de la plante et du fruit de tomate : application à des niveaux de salinité et de disponibilité hydrique variables." Avignon, 2009. http://www.theses.fr/2009AVIG0625.
Tomato production is very important in horticulture. The high competition on the world market emphasizes to improve fruit quality, whose criteria are complex. The modification of water and carbon status of the plant are an important key in developing the fruit quality. The effects of water and carbon factors on fruit quality are due to the plasticity observed in the functioning of the fruit, but also of the plant. By coupling experimental and modeling approaches, the effect of water and salt stress were studied (i) on the plant functioning. The interaction between the plant and fruit is described through the endogenous availability of water and carbon. In the first experiment (2006), tomato plants (Solanum lycopersicum L. Cv Marmara) were grown in greenhouses at four salinity levels (4, 7, 10 and 13 mS cm-1) during 6 monts of culture. In the 2nd experiment (2007), a water stress, for 15 days, was applied. These experiments have showed a significant effect on the fruit growth and quality (size, dry mass content), and on plant growth (biomass, leaf area). The architecture has been analyzed through the process of initiation and growth of the various organs : inflorescence, leaflet, rachis internodes. Regarding the organs initiation, the phyllocron was not affected, but the number of leaflets per leaf was reduced. Regarding the elongation process, the increased length of leaflet and internodes was associated with increased salinity. The formalization of the process of initiation and growth and the estimated parameters, allowed the construction of a 3D dynamic model of plant. This model allows and integrated description of the elementary scale of leaflets to the scale of culture, and the effect of salinity on plant architecture. The salt and water stress had a significant effect of the plant water status. The technique of facilitated exudation with EDTA was used to estimate the variable involved in carbon allocation within the plant. The sugar concentration in the phloem varied over the time and was affected by water stress. In addition, the phloem turgor pressure was significantly lowered by water stress, and appeared to vary according to, the position and /or nature of the organ (leaves, fruit). The local availability of resources (water and caron) has identified the condition at the insertion point of the fruit on the plant. A biophysical model of fruit growth (Fishman and Génard 1998) was adapted. Using a single set of parameters for all the dataset the dynamics of accumulation of fresh and dry mass in the fruit were correctly simulated. I n addition, the model was also used to estimate the driving variables (osmotic potential and turgor pressure) in the fruit and therefore the water and carbon flows between the plant and fruit, in response to environmental conditions
Lashermes, Gwenaëlle. "Évolution des polluants organiques au cours du compostage de déchets organiques : approche expérimentale et modélisation." Phd thesis, AgroParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00546943.
Gimenez, Audrey. "Etude des interactions entre diazotrophie, disponibilité nutritive et production planctonique dans l'océan de surface du pacifique tropical sud-ouest par une approche combinant observation et modélisation." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0208/document.
This work is part of the OUTPACE project which aimed to characterize the western tropical south Pacific (WTSP) in terms of biogeochemical stocks and fluxes and biological diversity of diazotrophs along a West-East longitudinal transect. This work combines an experimental with a modeling approach in order to study the role of diazotrophy in the planktonic dynamics and biogeochemical cycles of the WTSP surface waters. The values measured during the campaign, iespecially those of primary production (PP) and dissolved inorganic phosphate (DIP) turnover time, revealed a West-East gradient of productivity and nutrient availability, closely related to the spatial variability of N$_2$ fixation rates. The use of a mechanistic biogeochemical model (implemented in the Eco3M platform) explicitly including two compartments of diazotrophs and coupled with a vertical 1D physical model, allowed to highlight the fact that the absence / presence of diazotrophy could explain the contrast between the western regions of the Melanesian Archipelago (WMA) and the west of the south Pacific gyre (WGY). ). The model results showed that non-diazotrophic organisms benefited from the new nitrogen supply provided by nitrogen fixers, and that the surface planktonic production depended significantly on diazotroph activity, which is controlled by the phosphate availability in the west and by the iron availability in the east of the WTSP
Dai, Zhan Wu. "Analyse et modélisation de la croissance et de la composition biochimique des baies de raisin (Vitis vinifera L. ) en réponse à la disponibilité carbonée et hydrique." Avignon, 2009. http://www.theses.fr/2009AVIG0612.
The responses of berry growth and composition (sugars and acids) to intrinsic properties (seed and berry position within a cluster) and exterior factors (assimilate supply and water availability) were studied using both ecophysiological and modelling approaches. During two successive growth seasons, experiments were conducted on two red wine grape (Vitis vinifera L. ) cultivars, Cabernet Sauvignon and Merlot, which grew in greenhouse and/or vineyard. Leaf removing together with berry thinning and shoot girdling were applied to obtain different levels of assimilate supply. In addition, water supply was controlled to provide two level of water availability in one year. With the assistance of a mathematical growth function, seed effect on the final berry size was identified to control berry growth during the first rapid growth phase, while its effect on berry composition is indirect. In addition, number of seeds per berry was a major reason causing intra-cluster variation in berry size and malic acid concentration but not for concentrations of sugars and tartaric acid. Increasing assimilate supply resulted in increases in the average berry fresh weight and sugar concentration, decreases in acid concentration, and decline in the degree of variability in berry traits. Position effect on berry fresh weight, sugars and acid only occurred under assimilate limited conditions. This position effect was not due to differences in seed distribution or berry potential sink size between positions, but was likely ascribed to the relative position of a berry to the assimilate source. A refined SUGAR model (Génard and Souty, 1996) was adopted to grape berry and correctly simulated the negative effect of lowered leaf-to-fruit ratio and the positive effect of water shortage on sugar concentration. Model simulation further indicated that the decreasing leaf-to-fruit ratio reduced sugar import more than sugar metabolism and water dilution, causing a net decrease in sugar concentration. In contrast, the water shortage decreased sugar import less than sugar metabolism and water dilution, resulting in a net increase in sugar concentration. Similarly, berry fresh and dry mass was well reproduced by adopting the Fishman and Génard's (1998) growth model, accurately simulating the reduced berry fresh and dry mass caused by the low leaf-to-fruit ratio. Furthermore, model simulation of the intra-cluster variation in berry fresh and dry
Azem, Sadia. "Ordonnancement des systemes flexibles de production sous contraintes de disponibilite des ressources." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2010. http://tel.archives-ouvertes.fr/tel-00611830.
Persegol, Christian. "Modélisation et simulation de défaillances dans les systèmes de production discrets." Montpellier 2, 1990. http://www.theses.fr/1990MON20199.
Zille, Valérie. "Modélisation et évaluation des stratégies de maintenance complexes sur des systèmes multi-composants." Troyes, 2009. http://www.theses.fr/2009TROY0005.
Maintenance strategies based on RCM method are difficult to assess, due to some methodological difficulties whose resolution is the scientific scope of this PhD Thesis: - the systems considered are composed of numerous dependent components with different degradation and failure phenomena, - maintenance strategies are complex, based on different tasks and without a simple structure. The objective of this PhD Thesis is to propose a method to quantify maintained systems performances. We propose a modelling framework which takes into account all the phenomena that describe multi-component system behaviour and complex maintenance strategy impact. A two-level structure allows a detailed description of components degradation/failure behaviour, all the possible maintenance tasks realisation and the consequences on the system. A global cost criteria based on system unavailability and maintenance costs renders possible to compare different strategies. The approach is implemented by using Petri nets and Monte Carlo simulation. The method is validated through its application on two systems from EDF nuclear power plants: - system AGR study presents the possible utilisations and the results obtained, - system TPA study illustrates the application on a real system and helps to define some further developments on data integration
Brissaud, Florent. "Contributions à la modélisation et à l'évaluation de la sûreté de fonctionnement de systèmes de sécurité à fonctionalités numériques." Troyes, 2010. http://www.theses.fr/2010TROY0015.
The use of new technologies in safety-related systems gives rise to specific issues with respect to risk management, and it needs having probabilistic evaluation tools adapted to the in-creasing complexity of systems. The thesis works presented in this dissertation contribute to the dependability evaluation of safety-related systems, and especially for digital-based transmitters, which combine data acquisition with information processing and transmission. The aim is to extend the dependability model-ling methods in order to take at best the various interactions and dynamic behaviours of the systems into account. The first proposed model allows to represent the functional and material aspects of a safety system, the faults and failures, as well as the different relations between elements. This modelling framework is used as support to perform reliability analyses and uncertainty analyses with regard to parameters and model. A second contribution assumes the transmitters as part of control systems and aims to model the interactions between transmitters, and the interactions with the other systems’ components and the process, using a dynamic reliability framework
Limal, Steve. "Architectures de contrôle-commande redondantes à base d'Ethernet Industriel : modélisation et validation par model-checking temporisé." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2009. http://tel.archives-ouvertes.fr/tel-00468531.
Viani, Alessandra. "Fonctionnement hydro-glaciologique du bassin versant de l'Arve dans les Alpes françaises : variabilité climatique et sur la disponibilité de la ressource en eau." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU015/document.
Glacier recession and the anticipation of spring snow melt driven by a warming climate could lead to changes in the hydrological cycle affecting not only the headwater catchments but also the areas downstream. In order to correctly predict the magnitude of future possible changes and to consider appropriate strategies of water management, a good understanding of the interaction between glaciers, climate and hydrology is needed. The aim of this study is to assess the effect of climate variability on the hydro-glaciological behaviour and its consequence on water availability in the Arve River catchment (French Alps) since 1960. It covers 1958 km2 and is composed by five nested catchments (Arveyron d’Argentière, Arveyron de la Mer de Glace, Arve at Pont des Favrands, Arve at Sallanches and Arve at Bout du Monde), all influenced by glacier and snow melt but characterized by various percentages of glacier cover ranging from 5 to 53%. This research is based on a long dataset of in situ or remote sensing glaciological, meteorological, hydrological and snow cover area data.Trend analyses are performed on the hydrological and meteorological data at all the considered sites. The seasonal cycle of each catchment is fitted using a mathematical function, namely the asymmetric peak model, and changes in the discharge are related to observed changes in the meteorological variables and the glaciers’ evolution. Results point out a contrasting behaviour among the catchments characterized by different glacier covers, showing an increasing trend on the discharge values in highly glacierized catchments (with a glacier cover >30%) and a decrease in the low glacierized ones. The sensitivity of the seasonal cycle to the future climate is evaluated. In the mid-21st century the annual runoff would be reduced by 16% for Arveyron d’Argentière and 31% for Arveyron de la Mer de Glace. Over the summer season, a detailed quantification of each term of the hydrological balance equation, as well as their uncertainties, on the Argentière and Mer de Glace-Leschaux drainage basins allows to underline the importance of considering the groundwater transfers to represent and predict the hydro-glaciological behaviour of a considered catchment. Two different distributed temperature index melt models coupled with a linear reservoir discharge model are used on the Arveron d’Argentière catchment over the 1960–2009 period. The calibration is carried out against discharge only and with a multi- criteria approach considering the discharge, the snow cover area and the glacier-wide annual mass balance values at daily time step. Results demonstrate the suitability of the use of a classical degree day model in simulating the hydro-glaciological behaviour and the subglacial water production of a highly glacierized catchment. A KGE of 0.85 is obtained between the observed and simulate discharge values over the 1960–2004 period. The use of a multi-criteria approach seems to reduce the simulation uncertainties
Malrait, Luc. "Modeling and control of server systems : application to performance and dependability." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT100/document.
Server technology provides a means to support a wide range of on-line services and applications, such as web services, e-mail services, database services. However, their ad hoc configuration poses significant challenges to the performance, availability and economical costs of applications. In this thesis, we examine the impact of server configuration on the central trade-off between service performance and service availability. First, we model the behavior of single servers using fluid approximations. Second, we develop novel ad- mission control laws of central server systems. We provide several control laws for different combinations of quality-of-service and service level objectives. Among them, AM-C , the availability-maximizing admission control law, achieves the highest service availability while meeting given performance objective; PM-C is a performance-maximizing ad- mission control law that meets a desired availability target with the highest performance. We evaluate our fluid model and control techniques on the TPC-C industry-standard benchmark that implements a warehouse running on the PostgreSQL database server. Our experiments show that the proposed techniques successfully improve performance by up to 30 % while guaranteeing availability constraints. Furthermore, we extend this work to distributed server systems, that are widely used by Internet applications in the farm of server clusters and multi-tier systems. We present a distributed server model as a non-linear continuous-time model using analogies with fluid transfer. We then state an optimization problem for the control of distributed server systems. We provide an admission control that allows to get the highest service availability while a target performance level is guaranteed. Numerical evaluations of the proposed distributed model and control are presented, and show that the optimal configuration of such systems is not intuitive
Chalhoub, Maha. "Effet de l'apport de composts sur la dynamique hydrique du sol, la disponibilité de l'azote pour la culture et le lessivage du nitrate : cas d'un sol limoneux cultivé du Bassin parisien." Paris 11, 2010. http://www.theses.fr/2010PA112244.
This research aimed at evaluating the effect of repeated application of different types of urban composts on the dynamics of water and nitrogen (N) in a cultivated loamy soil. We conducted a field study to quantify the impact of compost on soil water dynamics, solute transport and nitrogen leaching. Ln addition to the monitoring of soil water potential and water content using tensiometers and TDRs, a tracer study was carried out to evaluate the effect of a compost application on the transport of non-sorbing conservative solutes in soiI. The dynamics of nitrogen was evaluated by sampling destructively the soil to measure its mineral nitrogen content. The deterministic soil-crop model PASTIS was used to simulate the observed water and N dynamics. Compost application affected the soil water properties only in the upper tilled horizon by increasing its water holding capacity and reducing cumulative evaporation under high evaporative demand. This could be explained by the increase in soil organic matter content after 10 years of compost application. Simulated N fluxes showed that the application of urban composts increased nitrogen availability for plants. Compost with high biodegradability presented higher nitrogen release the year following its application, while composts with low biodegradability allowed long term availability of N after several years of compost application
Brissaud, Florent. "Contributions à la Modélisation et à l'Évaluation de la Sûreté de Fonctionnement de Systèmes de Sécurité à Fonctionnalités Numériques." Phd thesis, Université de Technologie de Troyes, 2010. http://tel.archives-ouvertes.fr/tel-00553045.
Medina-Oliva, Gabriela. "Modélisation conjointe des connaissances multi-points de vue d'un système industriel et de son système de soutien pour l'évaluation des stratégies de maintenance." Phd thesis, Université Henri Poincaré - Nancy I, 2011. http://tel.archives-ouvertes.fr/tel-00702247.
Maha, Chalhoub. "Effet de l'apport de composts sur la dynamique hydrique du sol, la disponibilité de l'azote pour la plante et le lessivage du nitrate : cas d'un sol limoneux cultivé du bassin parisien." Phd thesis, Institut national agronomique paris-grignon - INA P-G, 2010. http://tel.archives-ouvertes.fr/tel-00784391.
Medina, Oliva Gabriela. "Modélisation conjointe des connaissances multi-points de vue d'un système industriel et de son système de soutien pour l'évaluation des stratégies de maintenance." Electronic Thesis or Diss., Nancy 1, 2011. http://www.theses.fr/2011NAN10092.
Nowadays, the importance of the maintenance function has increased, due to the requirements on the maintain in operational conditions phase (MCO) of the system-of-interest (SI). As well as for the relevant role of maintenance in improving availability, performance efficiency, total plant availability, etc. To control performances, maintenance managers should be able to make some choices about the maintenance strategies and the resources that can fulfil the requirements. Within this context, we propose a methodology to formalize a model allowing to perform simulation to assess maintenance strategies. The scientific contribution of our work is that this approach unify by using a probabilistic relational model (PRM), different kind of knowledge needed to assess maintenance strategies. Knowledge is presented as generic and modular patterns based on PRM. These patterns integrate relevant decisional variables of the system of interest and of its maintenance system. This approach eases the modeling phase for a specific application. This methodology is one of the results of the project ANR SKOOB. This approach was tested on an industrial case for the maintenance of a harvest production process
Medina, Oliva Gabriela. "Modélisation conjointe des connaissances multi-points de vue d'un système industriel et de son système de soutien pour l'évaluation des stratégies de maintenance." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10092/document.
Nowadays, the importance of the maintenance function has increased, due to the requirements on the maintain in operational conditions phase (MCO) of the system-of-interest (SI). As well as for the relevant role of maintenance in improving availability, performance efficiency, total plant availability, etc. To control performances, maintenance managers should be able to make some choices about the maintenance strategies and the resources that can fulfil the requirements. Within this context, we propose a methodology to formalize a model allowing to perform simulation to assess maintenance strategies. The scientific contribution of our work is that this approach unify by using a probabilistic relational model (PRM), different kind of knowledge needed to assess maintenance strategies. Knowledge is presented as generic and modular patterns based on PRM. These patterns integrate relevant decisional variables of the system of interest and of its maintenance system. This approach eases the modeling phase for a specific application. This methodology is one of the results of the project ANR SKOOB. This approach was tested on an industrial case for the maintenance of a harvest production process
Wagner, Fabien. "La réponse des forêts tropicales humides aux variations climatiques : évolution de la structure et de la dynamique des peuplements forestiers guyanais." Thesis, Antilles-Guyane, 2011. http://www.theses.fr/2011AGUY0481/document.
At a global scale tropical forest play a major role in term of carbon stock as well as in term of CO2 fluxes. Several studies have highlighted changes in tropical forest functioning during the last 20 years including a faster turnover and an increase of above ground biomass. The drivers of these changes are discussed and throughout this thesis we propose to contribute to this debate. We use the data from the Paracou experimental site in French Guiana established in 1984 on 120 hectares of moist tropical forest. Meteorological data come from the flux tower of the site, Guyaflux. We use annual and bisannual diameter measurements from the Guyafor database, and intra-annual diameter increments from the measurements of 260 trees near the flux tower.This thesis has two main parts. In the first part we present the biomass analysis of the Paracou permanent plots and the impact of structural changes in this forest on the carbon budget. The first part is constituted by two points. (i) Which temporal and spatial scale used to analyze the structure (biomass, basal area and stem density) and dynamics (tree growth, recruitment and mortality)components of tropical forest in order to minimized sample bias ? We establish a simple method to rely measurement interval between census and surface of measurement to the coefficient of variation of forests structure and dynamic components (ii) Which demographic process are involved in the explanation of biomass variation and how the biomass is distributed in the system ? The observed increase of biomass at Paracou could be link to the rarity of big trees mortality events. These big trees represent the larger part of the biomass. In the second part, we present the analysis of intra and inter-annual climate variation effects on forest dynamic changes. This part is divided in two points. (i) How to model drought stress in moist tropical forest ? We built a daily water balance model for tropical trees. (ii) Which climate variables explain the tree growth in guianian forests? We shown that soil water availability is the determinant factor of tree growth among a panel of climate variables. (iii) Which functional traits are involved in the tropical tree growth responses to climate? In this analysis, we determined that wood specific gravity, maximum tree height and tree diameter modulate the tree growth response to climate variations
Gandibleux, Jean. "Contribution à l'évaluation de sûreté de fonctionnement des architectures de surveillance/diagnostic embarquées. Application au transport ferroviaire." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2013. http://tel.archives-ouvertes.fr/tel-00990970.
Simache, Cristina. "Evaluation de la sûreté de fonctionnement de systèmes Unix et Windows à partir de données opérationnelles : méthode et application." Toulouse 3, 2004. http://www.theses.fr/2004TOU30280.
Academic and industrial computing environments are mainly based on interconnected heterogeneous systems including a large number of Unix, Windows NT and Windows 2000 workstations and servers. These environments are designed to facilitate resource sharing and cooperative work between users. However, these benefits may be compromised by failures affecting the communication network, the applications or the end systems. There is no better way to understand the behavior of computing environments in the presence of faults than by direct measurement, analysis and assessment based on data obtained from the observation of their behavior in an operational environment. Our work focuses on the development and the implementation of methods allowing data collection and dependability analysis of log files automatically recorded by some operating systems. The target systems in our study are Unix, Windows NT and Windows 2000 systems interconnected in a local area network. Besides the definition and the implementation of the data collection strategy, the data processing aims to extract the relevant information and to obtain quantitative measures in order to characterize the target systems from a dependability point of view. We also showed how the measures assessed from operational data can be integrated within an analytical modeling allowing the estimation of user-perceived availability. The comparative analysis of measures characterizing the systems and those reflecting users' perceptions represents another original result of our work
Sayad, Khaled. "Cross-domain Resilience in Cloud-native, Critical Cyber-Physical Systems Networks : Availability Modeling, Analysis, and Optimization of Critical Services Provisioning." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST028.
The dependability of Critical Infrastructures (CIs) operations is crucial to ensuresecurity and socio-economic stability in modern society. These CIs rely on a complex network of Critical Cyber-Physical Systems (CCPSs), spanning multiple domains such as telecommunication and energy, to guarantee a continuous ow of critical services. The paradigm shift in modern CIs' operational mode, illustrated by the increased integration of cloud-native technologies in the underlying CCPSs networks, brings more challenges in terms of resilience against cyber-risks, and increased deployment costs due to redundancy-based protection schemes. In this dissertation, we tackle these challenges by, first, proposing a model-based, cross-domain dependability evaluation to assess the availability of cloud-native, interdependent critical services and quantify the impact of adopting cross-domain protection mechanisms on critical services' dependability. Secondly, we study the problem of optimal service provisioning based on resource sharing in cloud-native, CCPSs networks with deployment cost and performance constraints. Finally, we tackle the problem of cross-domain coordination from a Trust perspective by proposing an architecture for secure and trustful information and resource sharing that exploits the convergence of cloud-native management and DataSpaces paradigm to ensure secure, trustful, and sovereign coordination
Broy, Perrine. "Evaluation de la sûreté de systèmes dynamiques hybrides complexes : application aux systèmes hydrauliques." Phd thesis, Université de Technologie de Troyes, 2014. http://tel.archives-ouvertes.fr/tel-01006308.
Pacoureau, Nathan. "Influence de la variabilité climatique, de l’abondance de proies, de la densité-dépendance et de l'hétérogénéité individuelle chez des prédateurs supérieurs longévifs : de l’individu à la population." Thesis, La Rochelle, 2018. http://www.theses.fr/2018LAROS026/document.
A fundamental endeavor in population ecology is to identify the drivers of population dynamics. The main objective of this thesis is to determine what are the demographic and population responses of superior marine predators to the fluctuations of their prey abundance, to climatic variations, to density-dependence while taking into account inter and intra individual heterogeneity (age, experience, sex, quality or strategy). To do this, we analysed long-term individual and population-based monitoring of long-lived seabirds and phylogenetically close apical predators in two contrasting biomes: the south polar skua Catharacta maccormicki at Pointe Géologie archipelago, Antarctica, and the brown skua Catharacta lonnbergi on the sub-Antarctic Kerguelen Archipelago. We will use direct abundance of their respective prey: Adélie penguin Pygoscelis adeliae and emperor penguin Aptenodytes forsteri in Antarctica, and the blue petrel Halobaena caerulea and the thin-billed prion Pachyptila belcheri prion in Kerguelen islands. These datasets provide a unique opportunity to simultaneously disentangle and quantify the different sources of variability driving variation in natural populations occupying one of the highest trophic levels of the Antarctic and sub-Antarctic food webs. We found variation in several vital traits of both populations influenced by individual performance and latent individual heterogeneity. We discuss the mechanisms by which climatic variability, prey abundance, and population density can differentially affect the different age classes of each age class, and the potential consequences of future environmental changes