Littérature scientifique sur le sujet « Optimisation multistage »
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Articles de revues sur le sujet "Optimisation multistage"
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Goryachkin, E. S., V. N. Matveev, G. M. Popov, O. V. Baturin et Yu D. Novikova. « Optimisation Method for Multistage Compressors ». Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no 3 (138) (septembre 2021) : 38–59. http://dx.doi.org/10.18698/0236-3941-2021-3-38-59.
Texte intégralRésumé :
The paper presents an algorithm for seeking an optimal blade configuration for multistage axial-flow compressors. The primary tool behind the algorithm is 3D CFD simulation, augmented by commercial optimisation software. The core of the algorithm involves feeding an initial data vector to the parametric simulation module so as to form a "new" blade geometry, which is then transferred to 3D computational software. The results obtained are further processed in a program that implements the algorithm for seeking the optimum and forms a new input data vector to achieve the set goal. We present a method of parametrically simulation the blade shape, implemented in a software package, making it possible to describe the shape of the compressor blade profiles using a minimum number of variables and to automatically change the shape in the optimisation cycle. The algorithm developed allows the main parameters of compressor operation (efficiency, pressure ratio, air flow rate, etc.) to be improved by correcting the profile shape and relative position of the blades. The algorithm takes into account various possible constraints. We used the method developed to solve practical problems of optimising multistage axial compressors of gas turbine engines for various purposes, with the number of compressor stages ranging from 3 to 15. As a result, the efficiency, pressure ratio and stability margin of gas turbine engines were increased
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Liu, Y. Z. « Studies on process optimisation of multistage atomisation ». Materials Science and Technology 18, no 8 (août 2002) : 929–34. http://dx.doi.org/10.1179/026708302225004766.
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Kwak, Doh-Soon, Kwang-Jae Kim et Myeong-Soo Lee. « Multistage PRIM : patient rule induction method for optimisation of a multistage manufacturing process ». International Journal of Production Research 48, no 12 (14 mai 2009) : 3461–73. http://dx.doi.org/10.1080/00207540902791827.
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Küttner, R., et J. Majak. « Multistage Optimisation Strategy For Solving Production Planning Problems ». IFAC Proceedings Volumes 42, no 2 (2009) : 332–37. http://dx.doi.org/10.3182/20090506-3-sf-4003.00061.
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Vasil'ev, S. V., M. A. Kuz'mina et V. A. Mishin. « Optimisation of a multistage pulsed dye laser system ». Quantum Electronics 31, no 6 (30 juin 2001) : 505–9. http://dx.doi.org/10.1070/qe2001v031n06abeh001989.
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Fatemifar, Soroush, Shahrokh Asadi, Muhammad Awais, Ali Akbari et Josef Kittler. « Face spoofing detection ensemble via multistage optimisation and pruning ». Pattern Recognition Letters 158 (juin 2022) : 1–8. http://dx.doi.org/10.1016/j.patrec.2022.04.006.
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Armstrong, M., A. Galli et R. Razanatsimba. « Using multistage stochastic optimisation to manage major production incidents ». Mining Technology 121, no 3 (septembre 2012) : 125–31. http://dx.doi.org/10.1179/1743286312y.0000000010.
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Yan, Zhou, Hany Hassanin, Mahmoud Ahmed El-Sayed, Hossam Mohamed Eldessouky, JRP Djuansjah, Naser A. Alsaleh, Khamis Essa et Mahmoud Ahmadein. « Multistage Tool Path Optimisation of Single-Point Incremental Forming Process ». Materials 14, no 22 (11 novembre 2021) : 6794. http://dx.doi.org/10.3390/ma14226794.
Texte intégralRésumé :
Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.
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Loveday, B. K., et A. L. Hemphill. « Optimisation of a multistage flotation plant using plant survey data ». Minerals Engineering 19, no 6-8 (mai 2006) : 627–32. http://dx.doi.org/10.1016/j.mineng.2005.09.014.
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Söylemez, Mehmet Sait. « On the thermo-economic optimisation of multistage flash evaporation desalination plants ». International Journal of Nuclear Governance, Economy and Ecology 4, no 2 (2014) : 153. http://dx.doi.org/10.1504/ijngee.2014.065935.
Texte intégralThèses sur le sujet "Optimisation multistage"
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Ghosh, Tushar Kanti. « Three dimensional modelling and optimisation of multistage collectors ». Thesis, Lancaster University, 2002. http://eprints.lancs.ac.uk/76623/.
Texte intégralRésumé :
Multistage collectors are commonly used in travelling wave tubes (TWTs), klystrons, gyrotrons and inductive output tubes (IOTs). A dc beam transfers some of its energy to the input RF wave during its travel through the interaction circuit. The purpose of a collector is to recover most of the remaining dc power from the spent beam and thereby increase both the collector and the overall efficiency. Secondary electrons play a detrimental role in collector performance. Use of the asymmetric collector geometries and application of a magnetic field in the collector region have proved to be effective in recapturing the secondaries. A fully three-dimensional simulator LKOBRA (MF) – the mainframe version of Lancaster KOBRA, has been developed at Lancaster University; this is capable of simulating multistage collectors including the effects of secondary electron emission and magnetic field. It is based on KOBRA3-INP1 but has been modified and improved together with the pre- and post-processors of the package. Efficiency is an important parameter in space applications of microwave tubes so it is always desirable to optimise the collector performance to maximise the overall tube efficiency. As a first step the potentials at the collector electrodes are optimised to achieve the maximum possible theoretical efficiency. A computer code based on the well-known enumerative technique has been developed for this purpose. In the next step the geometry of the collector electrodes is optimised using an automated design package that is based on a genetic algorithm. The genetic algorithm creates a new geometry through a search procedure that works from a population of possible geometries. A new set of geometries is generated using three basic operators namely reproduction, crossover and mutation. The collector efficiency is used as the fitness parameter in the genetic algorithm that produces a new population of geometries. This package has been used to optimise the efficiency of a 4-stage symmetric collector and a 2-stage asymmetric collector.
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Teiller, Alexandre. « Aspects algorithmiques de l'optimisation « multistage » ». Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS471.
Texte intégralRésumé :
En optimisation combinatoire classique, étant donné une instance d’un problème, il est demandé de trouver une bonne solution réalisable. Cependant, dans de nombreux cas, les données peuvent évoluer au cours du temps et il est demandé de résoudre une séquence d’instances. Gupta et al. (2014) et Eisenstat et al. (2014) ont proposé un modèle multistage où étant donné un horizon de temps, l’entrée est une séquence d’instances (une pour chaque pas de temps), et l’objectif est de trouver une séquence de solutions (une pour chaque pas de temps) qui atteindrait un compromis entre la qualité des solutions à chaque pas de temps et la stabilité/similarité des solutions pour des pas de temps consécutifs. Dans le Chapitre 1, nous présenterons un aperçu des problèmes d’optimisation prenant en compte des données évolutives. Dans le Chapitre 2, le problème du sac-à-dos est traité dans un contexte offline. La contribution principale est un schéma d’approximation polynomiale (PTAS). Dans le Chapitre 3, le cadre multistage est étudié pour des problèmes multistage dans un contexte online. La contribution principale est l’introduction d’une structure pour ces problèmes avec des bornes presque serrées supérieures et inférieures sur les meilleurs ratios compétitifs de ces modèles. Enfin, dans le Chapitre 4 est présenté une application directe du cadre multistage dans un contexte musical, i.e l’orchestration assistée par ordinateur avec son cible. Nous avons présenté une analyse théorique du problème, en montrant sa NP-difficulté, des résultats d’approximation ainsi que des expérimentationsN a classical combinatorial optimization setting, given an instance of a problem one needs to find a good feasible solution. However, in many situations, the data may evolve over time and one has to solve a sequence of instances. Gupta et al. (2014) and Eisenstat et al. (2014) proposed a multistage model where given a time horizon the input is a sequence of instances (one for each time step), and the goal is to find a sequence of solutions (one for each time step) reaching a trade-off between the quality of the solutions in each time step and the stability/similarity of the solutions in consecutive time steps. In Chapter 1 of the thesis, we will present an overview of optimization problems tackling evolving data. Then, in Chapter 2, the multistage knapsack problem is addressed in the offline setting. The main contribution is a polynomial time approximation scheme (PTAS) for the problem in the offline setting. In Chapter 3, the multistage framework is studied for multistage problems in the online setting. The main contribution of this chapter was the introduction of a structure for these problems and almost tight upper and lower bounds on the best-possible competitive ratio for these models. Finally in chapter 4 is presented a direct application of the multistage framework in a musical context i.e. the target-based computed-assisted orchestration problem. Is presented a theoretical analysis of the problem, with NP-hardness and approximation results as well as some experimentations
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Tran, Duy-Nghi. « Programmation dynamique tropicale en optimisation stochastique multi-étapes ». Thesis, Paris Est, 2020. http://www.theses.fr/2020PESC1040.
Texte intégralRésumé :
Dans cette thèse on s'intéresse à la résolution par programmation dynamique de problèmes d'Optimisation Stochastique Multi-étapes (OSM).En première partie, on s'est intéressé à l'approximation des fonctions valeurs d'un problème OSM par des combinaisons dîtes min-plus ou max-plus linéaires de fonctions basiques. Cette approche s'interprète comme l'analogue en algèbre tropicale de modèles paramétriques en programmation dynamique approximatives, notamment étudiés par Bertsekas et Powell.Dans le cadre simplifié des problèmes d'optimisation multi-étapes déterministes, nous introduisons un algorithme, appelé Programmation Dynamique Tropical (PDT), qui construit itérativement des approximations des fonctions valeurs comme combinaisons min-plus ou max-plus linéaires. A chaque itération, une trajectoire d'états est tirée aléatoirement et les états formant cette trajectoire sont appelés points de raffinements. Compte tenu des approximations courantes des fonctions valeurs, PDT calcule alors récursivement en remontant dans le temps, une nouvelle fonction basique à ajouter à la combinaison min-plus ou max-plus linéaire courante. La fonction basique ajoutée à l'approximation au temps t doit vérifier deux conditions de compatibilité : elle doît être exacte au t-ème point de rafinement et valide. PDT évite ainsi de discrétiser l'espace d'état dans sa totalité et tente de s'émanciper du fléau de la dimension.Notre première contribution, dans le cadre de problèmes multi-étapes déterministes, est l'obtention de conditions suffisantes sur la richesse des points de raffinements afin d'assurer presque sûrement la convergence asymptotique des approximations générées vers les fonctions valeurs, en des points d'intérêts.En seconde partie, on a étendu le cadre de l'algorithme PDT aux problèmes stochastiques multi-étapes Lipschitz où les bruits sont finis et indépendants. Dans ce cadre, on génère simultanément des approximations max-plus linéaires et min-plus linéaires des fonctions valeurs. A chaque itération, lors d'une phase vers l'avant, une trajectoire déterministe d'état particulière appelée trajectoire problème-enfant est générée. Ensuite, lors du phase en arrière dans le temps, les approximations courantes sont raffinées en ajoutant des fonctions basiques qui sont exactes et valides.Notre seconde contribution est la preuve que l'écart entre combinaisons linéaires max-plus et min-plus ainsi générées tend vers 0 le long des trajectoires problèmes-enfants. Ce résultat généralise un résultat de Baucke, Downward et Zackeri de 2018 qui prouvait la convergence d'un schéma similaire, introduit par Philpott, de Matos et Zackeri en 2013, dans le cadre de problèmes OSM convexes. Toutefois, la complexité algorithmique de l'extension de PDT présentée dépend fortement de la taille du support des bruits d'un problème OSM donné. En troisième partie, on s'est intéressé à quantifier l'écart entre les valeurs de deux problèmes OSM ne différant que par leur arbre de scénarios. Sous hypothèses de régularités, Pflug et Pichler ont montré en 2012 que la valeur d'OSM est lipschitzienne par rapport à la Distance Imbriquée qu'ils ont introduite. Toutefois le calcul de la Distance Imbriquée nécessite le calcul d'un nombre exponentiel, en la taille de l'horizon, de problèmes de transport optimal. Motivé par le succès de l'algorithme de Sinkhorn pour calculer une relaxation entropique du problème de transport optimal, en troisième contribution nous proposons une relaxation entropique de la Distance Imbriquée que nous illustrons numériquement. En dernière partie, afin de justifier la résolution par programmation dynamique dans des cas plus généraux, des échanges entre intégration et minimisation doivent être justifiés. En quatrième contribution, nous établissons un résultat général d'échange entre intégration et minimisation qui englobe certains résultats usuelsIn this thesis, we are interested in the resolution by dynamic programming of Multistage Stochastic optimization Problems (MSP).In the first part, we are interested in the approximation of the value functions of a MSP as min-plus or max-plus linear combinations of basic functions. This approach can be interpreted as the tropical algebra analogue of Approximate Dynamic Programming parametric models, notably studied by Bertsekas and Powell.In the simplified framework of multistage deterministic optimisation problems, we introduce an algorithm, called Tropical Dynamic Programming (TDP), which iteratively constructs approximations of value functions as min-plus or max-plus linear combinations. At each iteration, a trajectory of states is randomly drawn and the states forming this trajectory are called trial points. Based on the current approximations of the value functions, TDP then recursively calculates, by going back in time, a new basic function to be added to the current linear min-plus or max-plus combination. The basic function added to the approximation at time t must verify two compatibility conditions: it must be tight at the t-th trial point and valid. In this way TDP avoids discretising the entire state space and tries to emancipate itself from the curse of dimensionality.Our first contribution, within the framework of deterministic multistage optimization problems, is sufficient conditions on the richness of the trial points in order to ensure almost surely the asymptotic convergence of the generated approximations to the value functions, at points of interest.In the second part, the framework of the TDP algorithm was extended to Lipschitz MSPs where the noises are finite and independent. In this framework, max-plus linear and min-plus linear approximations of the value functions are generated simultaneously. At each iteration, in a forward phase, a particular deterministic trajectory of states called the problem-child trajectory is generated. Then, in the backward phase in time, the common approximations are refined by adding basic functions that are tight and valid.Our second contribution is the proof that the difference between the max-plus and min-plus linear combinations thus generated tends towards 0 along the problem-child trajectories. This result generalises a result from Baucke, Downward and Zackeri in 2018 who proved the convergence of a similar scheme, introduced by Philpott, de Matos and Zackeri in 2013, for convex MSPs. However, the algorithmic complexity of the TDP extension presented is highly dependent on the size of the noise support of a given MSP.In the third part, we are interested in quantifying the difference between the values of two MSPs differing only in their scenario tree. Under assumptions of regularities, Pflug and Pichler showed in 2012 that the value of such MSPs is Lipschitz-continuous with respect to the Nested Distance they introduced. However, the computation of the Nested Distance requires an exponential number (w.r.t. the horizon T) of computation of optimal transport problems.Motivated by the success of Sinkhorn's algorithm for computing entropic relaxation of the optimal transport problem, as a third contribution we propose an entropic relaxation of the Nested Distance which we illustrate numerically.Finally, in order to justify the resolution by dynamic programming in more general cases of MSPs, interchange between integration and minimisation must be justified. In the fourth contribution, we establish a general interchange result between integration and minimization which includes some usual results
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Guba, Nadine [Verfasser], Brigitte [Gutachter] Werners et Marion [Gutachter] Steven. « Energy portfolio optimisation under uncertainty : multistage stochastic models for optimising energy procurement and power plant operation planning / Nadine Guba ; Gutachter : Brigitte Werners, Marion Steven ; Fakultät für Wirtschaftswissenschaft ». Bochum : Ruhr-Universität Bochum, 2018. http://nbn-resolving.de/urn:nbn:de:hbz:294-61946.
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Guba, Nadine [Verfasser], Brigitte Gutachter] Werners et Marion [Gutachter] [Steven. « Energy portfolio optimisation under uncertainty : multistage stochastic models for optimising energy procurement and power plant operation planning / Nadine Guba ; Gutachter : Brigitte Werners, Marion Steven ; Fakultät für Wirtschaftswissenschaft ». Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1173421351/34.
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Guba, Nadine Verfasser], Brigitte [Gutachter] Werners et Marion [Gutachter] [Steven. « Energy portfolio optimisation under uncertainty : multistage stochastic models for optimising energy procurement and power plant operation planning / Nadine Guba ; Gutachter : Brigitte Werners, Marion Steven ; Fakultät für Wirtschaftswissenschaft ». Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1173421351/34.
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Hawaidi, Ebrahim A. M. « Simulation, optimisation and flexible scheduling of MSF desalination process under fouling. Optimal design and operation of MSF desalination process with brine heater and demister fouling, flexible design operation and scheduling under variable demand and seawater temperature using gPROMS ». Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5629.
Texte intégralRésumé :
Among many seawater desalination processes, the multistage flash (MSF) desalination process is a major source of fresh water around the world. The most costly design and operation problem in seawater desalination is due to scale formation and corrosion problems. Fouling factor is one of the many important parameters that affect the operation of MSF processes. This thesis therefore focuses on determining the optimal design and operation strategy of MSF desalinations processes under fouling which will meet variable demand of freshwater.
First, a steady state model of MSF is developed based on the basic laws of mass balance, energy balance, and heat transfer equations with supporting correlations for physical properties. gPROMS software is used to develop the model which is validated against the results reported in the literature. The model is then used in further investigations.
Based on actual plant data, a simple dynamic fouling factor profile is developed which allows calculation of fouling factor at different time (season of the year). The role of changing brine heater fouling factor with varying seawater temperatures (during the year) on the plant performance and the monthly operating costs for fixed water demand and fixed top brine temperature are then studied. The total monthly operation cost of the process are minimised while the operating parameters such as make up, brine recycle flow rate and steam temperature are optimised. It was found that the seasonal variation in seawater temperature and brine heater fouling factor results in significant variations in the operating parameters and operating costs.
The design and operation of the MSF process are optimized in order to meet variable demands of freshwater with changing seawater temperature throughout the day and throughout the year. On the basis of actual data, the neural network (NN) technique has been used to develop a correlation for calculating dynamic freshwater demand/consumption profiles at different times of the day and season. Also, a simple polynomial based dynamic seawater temperature correlation is developed based on actual data. An intermediate storage tank between the plant and the client is considered. The MSF process model developed earlier is coupled with the dynamic model for the storage tank and is incorporated into the optimization framework within gPROMS. Four main seasons are considered in a year and for each season, with variable freshwater demand and seawater temperature, the operating parameters are optimized at discrete time intervals, while minimizing the total daily costs. The intermediate storage tank adds flexible scheduling and maintenance opportunity of individual flash stages and makes it possible to meet variable freshwater demand with varying seawater temperatures without interrupting or fully shutting down the plant at any-time during the day and for any season.
Finally, the purity of freshwater coming from MSF desalination plants is very important when the water is used for industrial services such as feed of boiler to produce steam. In this work, for fixed water demand and top brine temperature, the effect of separation efficiency of demister with seasonal variation of seawater temperatures on the final purity of freshwater for both cleaned and fouled demister conditions is studied. It was found that the purity of freshwater is affected by the total number of stages. Also to maintain the purity of freshwater product, comparatively large number of flash stage is required for fouled demister.
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Hawaidi, Ebrahim Ali M. « Simulation, optimisation and flexible scheduling of MSF desalination process under fouling : optimal design and operation of MSF desalination process with brine heater and demister fouling, flexible design operation and scheduling under variable demand and seawater temperature using gPROMS ». Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5629.
Texte intégralRésumé :
Among many seawater desalination processes, the multistage flash (MSF) desalination process is a major source of fresh water around the world. The most costly design and operation problem in seawater desalination is due to scale formation and corrosion problems. Fouling factor is one of the many important parameters that affect the operation of MSF processes. This thesis therefore focuses on determining the optimal design and operation strategy of MSF desalinations processes under fouling which will meet variable demand of freshwater. First, a steady state model of MSF is developed based on the basic laws of mass balance, energy balance, and heat transfer equations with supporting correlations for physical properties. gPROMS software is used to develop the model which is validated against the results reported in the literature. The model is then used in further investigations. Based on actual plant data, a simple dynamic fouling factor profile is developed which allows calculation of fouling factor at different time (season of the year). The role of changing brine heater fouling factor with varying seawater temperatures (during the year) on the plant performance and the monthly operating costs for fixed water demand and fixed top brine temperature are then studied. The total monthly operation cost of the process are minimised while the operating parameters such as make up, brine recycle flow rate and steam temperature are optimised. It was found that the seasonal variation in seawater temperature and brine heater fouling factor results in significant variations in the operating parameters and operating costs. The design and operation of the MSF process are optimized in order to meet variable demands of freshwater with changing seawater temperature throughout the day and throughout the year. On the basis of actual data, the neural network (NN) technique has been used to develop a correlation for calculating dynamic freshwater demand/consumption profiles at different times of the day and season. Also, a simple polynomial based dynamic seawater temperature correlation is developed based on actual data. An intermediate storage tank between the plant and the client is considered. The MSF process model developed earlier is coupled with the dynamic model for the storage tank and is incorporated into the optimization framework within gPROMS. Four main seasons are considered in a year and for each season, with variable freshwater demand and seawater temperature, the operating parameters are optimized at discrete time intervals, while minimizing the total daily costs. The intermediate storage tank adds flexible scheduling and maintenance opportunity of individual flash stages and makes it possible to meet variable freshwater demand with varying seawater temperatures without interrupting or fully shutting down the plant at any-time during the day and for any season. Finally, the purity of freshwater coming from MSF desalination plants is very important when the water is used for industrial services such as feed of boiler to produce steam. In this work, for fixed water demand and top brine temperature, the effect of separation efficiency of demister with seasonal variation of seawater temperatures on the final purity of freshwater for both cleaned and fouled demister conditions is studied. It was found that the purity of freshwater is affected by the total number of stages. Also to maintain the purity of freshwater product, comparatively large number of flash stage is required for fouled demister.
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Mohammadi, Mehrdad. « A multi-objective optimization framework for an inspection planning problem under uncertainty and breakdown ». Thesis, Paris, ENSAM, 2015. http://www.theses.fr/2015ENAM0055/document.
Texte intégralRésumé :
Dans les systèmes manufacturiers de plus en plus complexes, les variations du processus de fabrication et de ses paramètres opératoires ainsi que leurs effets sur l’ensemble du système doivent être maîtrisés, mesurés et contrôlés. Cette thèse propose un cadre d’optimisation pour l’élaboration d’un plan d’inspection optimal qui permet une prise de décision opérationnelle afin d’assurer la satisfaction des objectifs stratégiques (réduction des coûts, amélioration de la qualité, augmentation de la productivité, …). La prise de décision se divise en trois questions : Quoi contrôler ? Comment contrôler ? Quand contrôler ? Le manque d'informations fiables sur les processus de production et plusieurs facteurs environnementaux est devenu un problème important qui impose la prise en compte de certaines incertitudes lors de la planification des inspections. Cette thèse propose plusieurs formulations du problème d’optimisation de la planification du processus d'inspection, dans lesquelles, les paramètres sont incertains et les machines de production sont sujettes aux défaillances. Ce problème est formulé par des modèles de programmation mathématique avec les objectifs : minimiser le coût total de fabrication, maximiser la satisfaction du client, et minimiser le temps de la production totale. En outre, les méthodes Taguchi et Monte Carlo sont appliquées pour faire face aux incertitudes. En raison de la complexité des modèles proposés, les algorithmes de méta-heuristiques sont utilisés pour trouver les solutions optimalesQuality inspection in multistage production systems (MPSs) has become an issue and this is because the MPS presents various possibilities for inspection. The problem of finding the best inspection plan is an “inspection planning problem”. The main simultaneous decisions in an inspection planning problem in a MPS are: 1) which quality characteristics need to be inspected, 2) what type of inspection should be performed for the selected quality characteristics, 3) where these inspections should be performed, and 4) how the inspections should be performed. In addition, lack of information about production processes and several environmental factors has become an important issue that imposes a degree of uncertainty to the inspection planning problem. This research provides an optimization framework to plan an inspection process in a MPS, wherein, input parameters are uncertain and inspection tools and production machines are subject to breakdown. This problem is formulated through several mixed-integer mathematical programming models with the objectives of minimizing total manufacturing cost, maximizing customer satisfaction, and minimizing total production time. Furthermore, Taguchi and Monte Carlo methods are applied to cope with the uncertainties. Due to the complexity of the proposed models, meta-heuristic algorithms are employed to find optimal or near-optimal solutions. Finally, this research implements the findings and methods of the inspection planning problem in another application as hub location problem. General and detail concluding remarks are provided for both inspection and hub location problems
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Nasri, Karima. « Frigo pompes à absorption multiétagées de haute performance : simulation et conception d'une maquette expérimentale ». Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL054N.
Texte intégralRésumé :
Ce travail se rapporte à l'étude de pompes à chaleur à absorption multiétagées, dans le but de développer des nouvelles machines frigorifiques de faible puissance pour la climatisation des bâtiments et utilisant la combustion du gaz naturel comme source de chaleur. Ce type de travail fait l'objet d'une demande de plus en plus importante car il s'avère être une solution de substitution intéressante à l'interdiction récente de production et d'utilisation des composés fluorés tels que les CFC (ChloroFluoroCarbures) et les HCFC (HydroChloroFluoroCarbures). Nous proposons donc dans ce travail, des structures de pompes à chaleur à absorption multiétagées pour frigo pompes qui offrent une excellente voie d'amélioration des performances par rapport aux systèmes simples mono-étages. Dans cette étude, nous nous intéressons plus particulièrement à développer les structures multiétagées en parallèle thermique au niveau du mélangeur, et ce pour une production maximale de froid utile. Ce principe nécessite un mélange qui présente un large domaine de travail (en pression et température). Le mélange utilisé dans cette étude est le couple Nh3/H2O de par ses propriétés et les données thermodynamiques le concernant qui sont assez bien connues. Pour améliorer les performances de ces systèmes, nous distinguons deux grandes voies. La première voie consiste à essayer de profiter de ce besoin de rectification, tandis que la seconde voie cherche à éliminer cette rectification.
Chapitres de livres sur le sujet "Optimisation multistage"
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Liu, Songsong, Jose M. Pinto et Lazaros G. Papageorgiou. « Medium-term planning of multistage multiproduct continuous plants using mixed integer optimisation ». Dans Computer Aided Chemical Engineering, 393–98. Elsevier, 2009. http://dx.doi.org/10.1016/s1570-7946(09)70066-5.
Texte intégralActes de conférences sur le sujet "Optimisation multistage"
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Engmark, Edda, Hanne Sandven, Stein-Erik Fleten et Gro Klaeboe. « Stochastic Multistage Bidding Optimisation in an Intraday Market with Limited Liquidity ». Dans 2018 15th International Conference on the European Energy Market (EEM). IEEE, 2018. http://dx.doi.org/10.1109/eem.2018.8469997.
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Motie, Mohadeseh, Peyman Moein, Ramin Moghadasi et Ali Hadipour. « Separator Pressure Optimisation and Cost Evaluation of a Multistage Production Unit Using Genetic Algorithm ». Dans International Petroleum Technology Conference. International Petroleum Technology Conference, 2019. http://dx.doi.org/10.2523/19396-ms.
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Motie, Mohadeseh, Peyman Moein, Ramin Moghadasi et Ali Hadipour. « Separator Pressure Optimisation and Cost Evaluation of a Multistage Production Unit Using Genetic Algorithm ». Dans International Petroleum Technology Conference. International Petroleum Technology Conference, 2019. http://dx.doi.org/10.2523/iptc-19396-ms.
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Li, H., D. Kalinin, A. Bruce et T. Bukovac. « Pioneering Beetaloo Shale Appraisal : Case Study of Australia's Largest Multistage Fracturing Operation ». Dans Asia Pacific Unconventional Resources Symposium. SPE, 2023. http://dx.doi.org/10.2118/217282-ms.
Texte intégralRésumé :
Abstract In the Beetaloo Sub-basin within the Northern Territory, Australia, the shales of the Velkerri and Kyalla Formation are highly prospective. The Carpentaria-3H well was drilled in the B Shale of the Amungee Member of the Velkerri Formation with a lateral length of more than 2,632 metres and completed over a 1,989-metre section. Beyond the appraisal nature of work, the observation of natural fractures and faulting coupled with geomechanical complexity posed multiple challenges to the planning, design, execution, and evaluation of Australia's largest stimulation job to date. This paper provides a comprehensive review of the Carpentaria-3H fracturing design and operation, following incorporating data from the Carpentaria-2H well. Completion design included developing the fracture stage interval spacing, number of clusters per stage, and cluster perforation density. For the fracturing treatment, decisions were refined for selection of fluid and proppant type, job volume optimisation and differentiation. Design optimisation is based upon both the simulator and evaluation measurements from the Carpentaria-2H reference well. Furthermore, observations from field execution, including formation response, experimental fracturing stages, and onsite design optimization, were incorporated. The largest multi-stage fracturing operation to date in Australia was completed with 12.8 million pounds of sand and proppant successfully placed without screen out across 40 stages. Across the multiple stages trials of sleeve-perforation comparison, out-of-target stages, variable sand size and ceramic proppant were successfully executed. During post-fracturing cleanup, the Carpentaria-3H produced at an average rate of 2.6 MMscf/D over 27 days prior to being shut-in for a period of "soaking". The success of the well completion through a multi-stage fracturing operation marked a breakthrough in Beetaloo Sub-basin appraisal and demonstrated that long lateral drilling and large-scale fracturing treatments can be a viable pathway to improve efficiency and return on investment. This is despite the limitations imposed by scarce infrastructure and challenging logistics in the Australian outback. Knowledge from the evaluation work undertaken in the previously stimulated and tested Carpentaria-2H wells was critical to advancing the Carpentaria-3H project. The Carpentaria-2H well's multi-arm calliper measurements offered enough precision to evaluate the perforation erosion following proppant placement. This generated a new technique for indirect evaluation of fluid and proppant distribution among the clusters. Production logging and chemical tracers also provided useful information for calibration and design optimization. Furthermore, advanced software tools were applied to integrate reservoir modelling, fracture and reservoir simulation, and data analysis.
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Wakeley, Guy R., et Ian Potts. « Origins of Loss Within a Multistage Turbine Environment Under Conditions of Partial Admission ». Dans ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-096.
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A partially admitted first stage is routinely used in a wide variety of turbo-machines to match the turbine swallowing capacity to the cycle pressure ratio over a range of outputs. Such a configuration is often favoured for applications in which optimised part-load efficiency is a design requirement. Partial admission is achieved by dividing the stator row into discrete arcs, each of which can be separately supplied with fluid. This arrangement creates circumferential discontinuities and considerable unsteadiness in the flow field within the intra-stage gap, and this unsteadiness can propagate through several downstream rows of fully admitted blading. In the current work an unsteady, multi-stage, multi-passage, Navier-Stokes solver has been validated against experimental results from a multistage axial flow air turbine. Interstage traverses of static and total pressure are shown to agree well with the CFD predictions, and the measured and predicted partial admission loss is compared with published correlations. It is further shown that the operating point of downstream stages is influenced by the degree of partial admission in the first stage. Additionally, increased alternating blade bending stresses are predicted. These phenomena are not included in any published turbine design methods, and are discussed within the context of large output steam turbine optimisation.
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Ibrahim, M. Z., M. M. Ibrahim, C. Findlay, T. Techanukul, M. F. Noor Hassim, K. Wongyaowarat et M. R. Ramli. « Cost and Operation Optimisation for Downhole Tractor Conveyance for Perforating in ERD Wells by Using Wireline Multistage Pressure Deployment System ». Dans IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition. Society of Petroleum Engineers, 2018. http://dx.doi.org/10.2118/191095-ms.
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Baert, Lieven, Ingrid Lepot, Caroline Sainvitu, Emmanuel Chérière, Arnaud Nouvellon et Vincent Leonardon. « Aerodynamic Optimisation of the Low Pressure Turbine Module : Exploiting Surrogate Models in a High-Dimensional Design Space ». Dans ASME Turbo Expo 2019 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91570.
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Abstract Further improvement of state-of-the-art Low Pressure (LP) turbines has become progressively more challenging. LP design is more than ever confronted to the need to further integrate complex models and to shift from single component design to the design of the complete LPT module at once. This leads to high-dimensional design spaces and automatically challenges its applicability within an industrial context, where CPU resources are limited and the cycle time crucial. The aerodynamic design of a multistage LP turbine is discussed for a design space defined by 350 parameters. Using an online surrogate-based optimisation (SBO) approach a significant efficiency gain of almost 0.5pt has been achieved. By discussing the sampling of the design space, the quality of the surrogate models, and the application of adequate data mining capabilities to steer the optimisation, it is shown that despite the high-dimensional nature of the design space the followed approach allows to obtain performance gains beyond target. The ability to control both global as well as local characteristics of the flow throughout the full LP turbine, in combination with an agile reaction of the search process after dynamically strengthening and/or enforcing new constraints in order to adapt to the review feedback, illustrates not only the feasibility but also the potential of a global design space for the LP module. It is demonstrated that intertwining the capabilities of dynamic SBO and efficient data mining allows to incorporate high-fidelity simulations in design cycle practices of certified engines or novel engine concepts to jointly optimise the multiple stages of the LPT.
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Ramsden, K. W. « An Interactive Methodology for Axial Compressor Design Teaching ». Dans ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-449.
Texte intégralRésumé :
The implementation of new technology in the gas turbine industry is accelerating at a rate which demands increasing specialisation by its engineering design staff. Simultaneously, this industry has been adopting concurrent engineering practices to reduce product lead-time. Accordingly, the industry now requires its engineers to acquire early competence in a wide range of technological disciplines. In addition, the individual must have a thorough understanding of the impact of component design decisions on both other components and on the engine as a whole. Against this background, gas turbine educational providers must respond to these increasing demands with teaching programmes that facilitate a faster and deeper understanding of this very complex product. The ambition of the teacher, however, to adequately prepare the student will continue to be limited by time constraints within lecture courses. Hitherto, this has normally resulted in class worked examples which are necessarily narrow in scope and confined to a limited range of design cases. This paper describes a teaching methodology which is structured to facilitate in-depth understanding of the key interactions between aerodynamics, thermodynamics and mechanical integrity arising in axial compressor design optimisation. This is achieved interactively through a combination of lectures, a hand worked multistage preliminary compressor design, a series of personal computer based design optimisation workshops and a final collective design assessment.
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Ahdeema, Jamal, Morteza Haghighat Sefat et Khafiz Muradov. « Hybrid Optimization Technique Allows Dynamic Completion Design and Control in Advanced Multilateral Wells with Multiple Types of Flow Control Devices ». Dans SPE Offshore Europe Conference & Exhibition. SPE, 2023. http://dx.doi.org/10.2118/215507-ms.
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Abstract Designing a well completion for multilateral wells with multiple types of flow control devices (FCDs) can be a challenging optimization task due to a large number of correlated control variables and computationally demanding objective functions. Consequently, standard optimization workflows may fail to find the optimal design. The lack of a reliable optimisation workflow has forced the industry to adopt a simplified, snapshot approach to intelligent completion design, ignoring long-term dynamic reservoir performance. In this work, a multistage optimization workflow named hybrid optimization (HO), has been developed for effectively optimizing the completion design of multilateral wells that are equipped with multiple types of FCDs. Differential evolution (DE), a metaheuristic optimisation algorithm, is utilized for initial exploration of the search space to identify promising regions, while the generated data are employed to develop a fast surrogate model to mimic the dynamic performance of the computationally expensive reservoir model. Global sensitivity analysis using the Sobol method is then performed with the aid of the developed and tested surrogate model, to divide control parameters into high and low impact groups. The Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm is employed at the final optimisation stage to perform a refined search in the optimal areas previously identified. The proposed framework offers engineers a set of guidelines to adjust the completion design, by modifying the most critical design parameters, in order to maximize production performance while minimizing installation and operational risks. The new workflow has been tested on a 3-D, synthetic, representative reservoir model developed by an intelligent dual-lateral well equipped with inflow control devices (ICDs) inside the laterals, and interval control valves (ICVs) at the laterals’ junctions. The developed HO technique showed superior performance as compared to the current, standard optimization options relying on a single algorithm. It allows efficient dynamic optimization and delivers reliable results in a reasonable time, to replace the snap-shot designs which can be sub-optimal due to their dependency on a single timestep.
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Krishnababu, Senthil, Vili Panov, Simon Jackson et Andrew Dawson. « Quick Start of an Industrial Gas Turbine Engine Through the Development of “Silent Start” VGV Schedule ». Dans ASME Turbo Expo 2020 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15983.
Texte intégralRésumé :
Abstract In this paper, research that was carried out to optimise an initial variable guide vane schedule of a high-pressure ratio, multistage axial compressor is reported. The research was carried out on an extensively instrumented scaled compressor rig. The compressor rig tests carried out employing the initial schedule identified regions in the low speed area of the compressor map that developed rotating stall. Rotating stall regions that caused undesirable non-synchronous vibration of rotor blades were identified. The variable guide vane schedule optimisation carried out balancing the aerodynamic, aero-mechanical and blade dynamic characteristics gave the ‘Silent Start’ variable guide vane schedule, that prevented the development of rotating stall in the start regime and removed the non-synchronous vibration. Aerodynamic performance and aero-mechanical characteristics of the compressor when operated with the initial schedule and the optimised ‘Silent Start’ schedule are compared. The compressor with the ‘Silent Start’ variable guide vane schedule when used on a twin shaft engine reduced the start time to minimum load by a factor of four and significantly improved the operability of the engine compared to when the initial schedule was used.