Дисертації з теми "Optimisation MINLP"
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Boix, Marianne. "Optimisation multicritère de réseaux d'eau." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0078/document.
This study presents a multiobjective optimization of industrial water networks through mathematical programming procedures. A large range of various examples are processed to propose several feasible solutions. An industrial network is composed of fixed numbers of process units and regenerations and contaminants. These units are characterized by a priori defined values: maximal inlet and outlet contaminant concentrations. The aim is both to determine which water flows circulate between units and to allocate them while several objectives are optimized. Fresh water flow-rate (F1), regenerated water flow-rate (F2),interconnexions number (F3), energy consumption (F4) and the number of heat exchangers (F5) are all minimized. This multiobjective optimization is based upon the epsilon-constraint strategy, which is developed from a lexicographic method that leads to Pareto fronts. Monocontaminant networks are addressed with a mixed linear mathematical programming (Mixed Integer Linear Programming, MILP) model, using an original formulation based on partial water flow-rates. The obtained results we obtained are in good agreement with the literature data and lead to the validation of the method. The set of potential network solutions is provided in the form of a Pareto front. An innovative strategy based on the GEC (global equivalent cost) leads to the choice of one network among these solutions and turns out to be more efficient for choosing a good network according to a practical point of view. If the industrial network deals with several contaminants, the formulation changes from MILP into MINLP (Mixed Integer Non Linear Programming). Thanks to the same strategy used for the monocontaminant problem, the networks obtained are topologically simpler than literature data and have the advantage of not involving very low flow-rates. A MILP model is performed in order to optimize heat and water networks. Among several examples, a real case of a paper mill plant is studied. This work leads to a significant improvement of previous solutions between 2 to 10% and 7 to 15% for cost and energy consumptions respectively. The methodology is then extended to the optimization of eco-industrial parks. Several configurations are studied regarding the place of regeneration units in the symbiosis. The best network is obtained when the regeneration is owned by each industry of the park and allows again of about 13% for each company. Finally, when heat is combined to water in the network of the ecopark, a gain of 11% is obtained compared to the case where the companies are considered individually
Hijazi, Hassan. "Optimisation non-linéaire mixte en nombres entiers pour la conception de réseaux en télécommunications." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22107/document.
In our work, we rely on the powerful arsenal of mathematical programming theory to model telecommunication problems and devise efficient methods for solving them. Our goal is to comply to real life constraints when defining optimal routing strategies and designing efficient capacity planning tools. Theoretical contributions apply the field of Mixed Integer Non-Linear Optimization. Among relevant results, let us mention :Explicit formulations of convex hulls in disjunctive programming, generalizing the famous perspective formulationsTractable compact formulations of problems featuring inerval uncertainty in Robust OptimizationAn efficient Outer-Inner approximation algorithm for solving large families of separable mixed Integer Non-Linear Programs (MINLPs) and Second Order Cone Programs (SOCPs), outperforming state-of-the-art commercial solvers.In the application part, our work aims at introducing reliable telecommunication networks, offering appropriate and guaranteed Quality of Service to all its customers. Today, Wide Access Networks (WAN), Virtual Private Networks (VPN) or IP-based Backbones carry a wide range services, namely: voice, video streaming and data traffic. Each one of these contents has its own performance requirements. Unfortunately, best effort algorithms are implemented at all levels, offering no guarantee for delay sensitive applications. Is it possible to build routing strategies guaranteeing upper bounds on source-to-destination delays? Can we make these routing protocols to delay variation ? Does service differentiation affect capacity planning decisions ? Answers to these questions will be developed in this thesis
Gugenheim, Dan. "Modélisation et optimisation d’un réseau de transport de gaz." Phd thesis, Toulouse, INPT, 2011. http://oatao.univ-toulouse.fr/11760/1/gugenheim.pdf.
Guo, Kunpeng. "Optimisation of plate/plate-fin heat exchanger design." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/optimisation-of-plateplatefin-heat-exchanger-design(e019a7a5-4be1-4350-b219-3387fd12f7d1).html.
Sowgath, Md Tanvir. "Neural network based hybrid modelling and MINLP based optimisation of MSF desalination process within gPROMS : development of neural network based correlations for estimating temperature elevation due to salinity, hybrid modelling and MINLP based optimisation of design and operation parameters of MSF desalination process within gPROMS." Thesis, University of Bradford, 2007. http://hdl.handle.net/10454/10998.
Marty, Fabien. "Optimisation de la structure globale des activités de surface d’une centrale géothermique à cogénération électricité/chaleur." Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3021/document.
A consortium of ten partners, led by “FONROCHE Géothermie”, works on the FONGEOSEC project, an “Investissement d’Avenir” organized by the French Agency for Environment and Energy (ADEME). The aim of this project is to design and create an innovative demonstrator of a high-energy geothermal power plant. The geothermal energy will be used to produce electricity and heat. Among other tasks, this project aims to develop a support tool for the optimal design of the structure for the surface activities in the geothermal plant.Within the developed tool, the repartition between electricity and heat production is in parallel. The geothermal fluid is split in two streams, one is used for an Organic Rankine Cycle (ORC) for electricity production, and the other is connected to a District Heating Network (DHN) for the heat distribution. This tool enables to determine simultaneously:which is the best repartition between electricity and heat,which is the best sizing for ORC components,which is the best configuration for the DHN.About the ORC, the tool will enable to decide if the use of an Internal Heat Exchanger (IHE) is interesting or not. For the DHN point of view, all the consumers envisaged are not mandatory. The tool will enable to choose which consumers it is better to connect to the network and in which disposition. The use of discrete variables is necessary and the optimization problem to be solved is a MINLP (Mixed Integer Non Linear Programming) problem.A solution strategy is implemented in order to obtain a confident solution with a determinist algorithm. This strategy is tested for different study cases close to FONGEOSEC conditions. Stability and Robustness of this strategy are then highlighted. An economic and an exergetic analysis are carried out. In order to find a good compromise between the two objectives, a multi-objective solution is performed. Finally, the diversity of results obtained shows it is not suitable to dissociate ORC and DHN studies and shows the interest of the developed tool
Cafieri, Sonia. "From local to global and back : a closed walk in mathematical programming and its applications." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00979273.
Vidal, Emmanuel. "Stratégie de planification pour la flexibilité opérationnelle d'un atelier à cheminement unique." Toulouse, INPT, 2000. http://www.theses.fr/2000INPT041G.
The management of a production shop aims at finding the best compromise between commercial, financial and industrial requirements. This survey deals with the characterization of "flexibility tools" in flow shop, to ensure the system's operational flexibility, that is its ability to comply with familiar changes. The different criteria are taken into account in a global manner, without favoring "a priori" one of them. So is the "convergence" between the required resources, to carry out the production planning, and the ones set to work favored ; that's why the objective function brings together different types of costs, such as work in progress, inventory, workforce, inactivity and the consequences of the perturbations. Some criteria of minor importance have also been defined. The problem has been approached by two different methods : - the first one, so called "global approach", process simultaneously all the variables, under a mixed integer non linear programming (MINLP) formulation ; - the second one, so called "sequential approach", is based on a decomposition of the problem into sub-problems, to solve them using genetic algorithms at first with a mono-objective formulation, and at second with a multi-objective formulation, that uses the secondary criteria. A small sized example illustrates this approach, to validate the decomposition of the problem into sub-problems and the use of heuristics ; then a bigger example is shown, that is realistic towards a real life industrial configuration
Mertz, Théophile. "Optimisation simultanée de la configuration et du dimensionnement des réseaux de chaleur urbains." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3019/document.
The aim of this thesis is to develop a method that provides design assistance for District Heating Network (DHN). This tool allows simultaneously the optimization of the configuration and its sizing, thanks to an MINLP formulation (Mixed Integer Non-Linear Programming). Binary variables help to choose the optimal configuration (network layout and technologies of production), whereas continuous variables help DHN sizing (temperature, diameter, velocity, heat exchanger area, thermal generating capacity …). The objective function to minimize is the total cost (capex and opex), subjected to numerous nonlinear constraints (e.g. thermal losses, pressure drop, energy balance).This method enables to design temperature cascade between consumers, when consumer temperature requirements are different, and also looped network (only one pipe in one trench). It helps also the decision to connect (or not) consumers to the main network and also the location(s) and type(s) of the heating plant. Moreover, the arbitrage between heat losses and pressure drops is taken into account thanks to physical considerations (non-linear equations). Eventually, it is possible to design 4th generation DHN and prove their financial profitability over the long terms (30 years). First a multi-step resolution strategy is proposed to ensure finding global optimum of the complex MINLP problem. Then academic study cases are analyzed to underline the numerous assets of the formulation. Finally, the optimal design compared to an existing DHN ensures the consistency of the method and allows to build a study case at a wider scale, which can be solved thanks to the comprehensive strategy developed. The design assistance method is available for initial design as well as for extension of existing DHN
Zhao, Qiao. "Conception and optimization of supercritical CO2 Brayton cycles for coal-fired power plant application." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0080/document.
Efficiency enhancement in power plant can be seen as a key lever in front of increasing energy demand. Nowadays, both the attention and the emphasis are directed to reliable alternatives, i.e., enhancing the energy conversion systems. The supercritical CO2 (SC-CO2) Brayton cycle has recently emerged as a promising solution for high efficiency power production in nuclear, fossil-thermal and solar-thermal applications. Currently, studies on such a thermodynamic power cycle are directed towards the demonstration of its reliability and viability before the possible building of an industrial-scale unit. The objectives of this PhD can be divided in two main parts: • A rigorous selection procedure of an equation of state (EoS) for SC-CO2 which permits to assess influences of thermodynamic model on the performance and design of a SC-CO2 Brayton cycle. • A framework of optimization-based synthesis of energy systems which enables optimizing both system structure and the process parameters. The performed investigations demonstrate that the Span-Wagner EoS is recommended for evaluating the performances of a SC-CO2 Brayton cycle in order to avoid inaccurate predictions in terms of equipment sizing and optimization. By combining a commercial process simulator and an evolutionary algorithm (MIDACO), this dissertation has identified a global feasible optimum design –or at least competitive solutions– for a given process superstructure under different industrial constraints. The carried out optimization firstly base on cycle energy aspects, but the decision making for practical systems necessitates techno-economic optimizations. The establishment of associated techno-economic cost functions in the last part of this dissertation enables to assess the levelized cost of electricity (LCOE). The carried out multi-objective optimization reflects the trade-off between economic and energy criteria, but also reveal the potential of this technology in economic performance
Quintero, Masselski Christian Steven. "Conception des procédés par optimisation de superstructures pour l'usine du futur (PRO-FUTUR)." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0103.
Projections from the International Renewable Energy Agency (IRENA) support that by the year 2050, electricity will be the main energy carrier with 50 % of the share of the energy market. The deployment of clean energy production and its integration to the energy market will play a key role towards this objective. Also, the quest for more efficient, sustainable and economic processes is one important challenge that process engineers are constantly facing in research and industry, which commonly need to determine the best structural configuration of a process, leading to the optimal interconnection of the processing units, with the respective set up of the operating conditions. This task would require evaluating several process designs to find the best configuration, which is a tedious and time-consuming approach to execute manually. Therefore, this work is foreseen to enable a practical methodology for process engineers to evaluate multiple process alternatives within a unique superstructure, to determine the best structural arrangement, the set of operating conditions and/or design parameters, leading towards the optimal process configuration regarding some economic, energetic and/or environmental criteria. The methodology is applied to a scenario of energy storage in ammonia, using as reference the conventional Haber-Bosch process. Four process superstructures have been proposed and evaluated to determine the best process structure, which include the selection of: (i) the number of compressors in the main compression stage; (ii) the number of catalytic reactors; (iii) the catalytic material, either Fe-based or Ru-based; (iv) the reactor arrangement, either multibed adiabatic or multitube autothermal; (v) the cooling system for the adiabatic reactors, either indirect (AICR) or direct (AQCR); (vi) the use of intermediate separation; (vii) the separation technology, among the condenser, membrane filters, and PSA; (viii) the use of pressure equalization on the permeate streams of the membrane filters; (ix) the use of an additional condenser after the separation by membranes or by PSA. The main results found through the optimization of these superstructures, allowed to determine that the best structural arrangement consists of two autothermal reactors in series, using the Ru-based catalyst, with two stages of compression, with intermediate and final separation by condensation. This configuration allows to produce 3 994.8 tNH3/y, representing an LCOA of 790.3 €/tNH3, and an energy efficiency of 67.13 %. The specific power consumption of the complete scenario is equal to 10.23 kWh/kgNH3, with the best available technology for ammonia synthesis, based on hydrogen from natural gas, consuming 27.4 GJ/tNH3. The main driver of the energy consumption is the electrolyser, responsible for 9.09 kWh/kgNH3 (88.85 %), while the nitrogen production represents 0.68 kWh/kgNH3 (6.65 %), and the HB synthesis loop consumes 0.46 kWh/kgNH3 (4.50 %)
Apostolou, Matthildi. "Méthodologie pour la conception optimisée des réseaux de chaleur et de froid urbains intégrés." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM072/document.
This thesis presents a mathematical optimization model and a methodology for the optimal design of district heating and cooling networks. The various constraints in energy balances, costs and environmental criteria can be considered in order to propose structures of flexible and innovative networks.The model allows the consideration of heating (or cooling) networks at different temperature levels, as well as different production sites and heat demands. The network’s layout as well as the optimal architecture of the heat production systems are achieved by minimizing either the total exergy consumed or the total cost for the investment and operation of the systems.The developed mathematical model is formulated into a multi-period MINLP problem. The constraints of the model are presented in nested models. The first model M1 considers the multi-period aspect and includes the constraints related to the heat exchanges between production/demand streams with the network and a thermal storage. The second model, called M2, contains the entire model M1 as well as new constraints for sizing heat pumps with variable COP. The model M3 includes the model M2 as well as new constraints for the geographical layout of the networks and the consideration of electricity balance in the problem.A methodology is also presented making it possible, using the model M3, to deal with complex and realistic case studies. The methodology proposes a decomposition of the problem following three consecutive steps. This methodology is then used for the optimization of a new district, considering heat pumps, seasonal heat storage and PV production
Rodríguez, Tello Eduardo A. "Nouvelles fonctions d'évaluation pour les problèmes d'étiquetage de graphes BMP et MinLA." Angers, 2007. http://www.theses.fr/2007ANGE0058.
This thesis deals with the development of new evaluation functions aiming at improving the performance of heuristic algorithms developed for solving combinatorial optimisation problems. In particular, we are interested in the improvement of the results obtained for two NP-hard graph labeling problems : the Bandwidth Minimization (BMP) and the Minimum Linear Arrangement (MinLA). To accomplish it, two evaluation functions, noted respectively δ and ϕ, are introduced. Contrary to the classical functions, they incorporate information on the problem's characteristics in order to improve their guidance capacities. Experimental comparisons were carried out by using different algorithms to assess the practical usefulness of the δ and ϕ functions. The results confirm that our functions allow to considerably improve the performances of the studied algorithms. Finally, the implementation of two simulated annealing algorithms, called RSA-δ and RSDP-ϕ, has made possible to take advantage of the new functions proposed, but also of other advanced components. The experimental comparisons between our algorithms and the state-of-the-art heuristics, carried out on benchmark instances from the literature, show that RSA-δ and RSDP-ϕ are very competitive. Indeed, they allow us to significantly improve the best-known results for many benchmarks
Fournier, David. "Metro regenerative braking energy : optimization through rescheduling : mathematical model and greedy heuristics compared to MILP and CMA-ES." Paris 7, 2014. http://www.theses.fr/2014PA077144.
The use of regenerative braking is a key factor to reduce the energy consumption of a metro line. In the case where no device can store the energy produced during braking, only the metros that are accelerating at the same time can benefit from it. Maximizing the power transfers between accelerating and braking metros thus provides a simple strategy to benefit from regenerative energy without any other hardware device. In this thesis, we use a mathematical timetable model to classify various metro energy optimization rescheduling problems studied in the literature and prove their NP-hardness by polynomial reductions of SAT. We then focus on the problem of minimizing the global energy consumption of a metro timetable by modifying the dwell times in stations. We present a greedy heuristic algorithm which aims at locally synchronizing braking metros along the timetable with accelerating metros in their time neighbourhood, using a non-linear approximation of energy transfers. On a benchmark of six small size timetables, we show that our greedy heuristics performs better than CPLEX using a MILP formulation of the problem, even when it is able to prove the optimality of a linear approximation of the objective function. We also show that it runs ten times faster than a state-of-the-art evolutionary algorithm, called the covariance matrix adaptation evolution strategy (CMA-ES), using the saure non-linear objective function on these small size instances. On real data leading to 10000 decision variables on which both MILP and CMA-ES do not provide solutions, the dedicated algorithm of our thesis computes solutions with a reduction of energy consumption ranging from 5% to 9%
De, León Almaraz Sofia. "Multi-objective optimisation of a hydrogen supply chain." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0009/document.
Hydrogen produced from renewable sources and used in fuel cells both for mobile and stationary applications constitutes a very promising energy carrier in a context of sustainable development. Yet the strategic roadmaps that were currently published about the energy potentialities of hydrogen at European, national and regional level as well as the analysis of the scientific publications in this field have identified the lack of infrastructures as a major barrier to the development of a « hydrogen » economy. This study focuses on the development of a methodological framework for the design of a hydrogen supply chain (HSC) (production, storage and transportation). The formulation based on mixed integer linear programming involves a multi-criteria approach where three objectives have to be optimised simultaneously, i.e., cost, global warming potential and safety risk, either at national or regional scale. This problem is solved by implementing lexicographic and Ɛ-constraint methods. The solution consists of a Pareto front, corresponding to different design strategies in the associated variable space. Multiple choice decision making based on M-TOPSIS (Modified Technique for Order Preference by Similarity to Ideal Solution) analysis is then selected to find the best compromise. The mathematical model is applied to a case study reported in the literature survey and dedicated to Great Britain for validation purpose, comparing the results between mono- and multi-objective approaches. In the regional case, the modelling and optimisation of the HSC in the Midi-Pyrénées region was carried out in the framework of the project “H2 as a green fuel”. A mono/multi period problem is treated with different optimisation scenarios using Ɛ-constraint and lexicographic methods for the optimisation stage. The geographic information system (GIS) is introduced and allows organising, analysing and mapping spatial data. The optimisation of the HSC is then applied to the national case of France. The objective is twofold: on the one hand, to examine if the methodology is robust enough to tackle a different geographic scale and second to see if the regional approach is consistent with the national scale. In this case study, the ArcGIS® spatial tool is used before optimisation to identify the geographic items that are further used in the optimisation step. A scenario with an economic cycle is also considered. Mono- and multi-objective optimisations exhibit some differences concerning the degree of centralisation of the network and the selection of the production technology type and size. The obtained results confirm that different spatial and temporal scales are required to encompass the complexity of the problem
Ben, Houria Zeineb. "Optimisation de la gestion du service de maintenance biomédicale." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES057/document.
The hospital is a world that is both sensitive and complex, sensitive because the human life is involved and complex because medical facilities are growing in number and in technical complexity. Then, the problem of the medical equipment maintenance in order to keep them in safe, reliable and with high level of availability has become a major preoccupation of the hospital. The objective of this thesis is to provide tools to help the biomedical maintenance service of the hospital to make decisions that allow a better control of costs, while ensuring patient and user safety and maintaining optimal performance of medical equipment. First, a heuristic has been proposed for the choice of internalization or outsourcing maintenance and for the selection of the appropriate contract. The selection of the contract is based on a set of criteria while considering the available budget constraint. Then, to improve the proposed procedure, we proposed multi-criteria decision-making tools to select the appropriate maintenance strategies. Seven criteria have been designed to study the criticality of medical equipment and the choice of maintenance by providing a coupling of the AHP approach "Analytical Hierarchy Process" with TOPSIS technique "Technique for Order Performance by Similarity to Ideal Solution." As the expert judgments of the maintenance department presented some uncertainty, we integrated the fuzzy language assessment of the criticality of the equipment and the selection of the maintenance strategy (Fuzzy AHP coupled with Fuzzy TOPSIS). A mixed integer linear programming model (MILP) was developed to define thresholds of criticality to characterize the three maintenance strategies. According to these thresholds, maintenance cost can be optimized within the available budget. Finally, a second mixed integer linear programming model (MILP) was developed based on the proposed heuristic. This model allows selecting for each equipment, the maintenance strategy, the internalization or the outsourcing of the maintenance and the type of contract while considering the available budget and the workload / capacity of the maintenance department
Gun, Philip. "Multi Vehicle Trajectory Planning On Road Networks." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/25389.
Giarola, Sara. "Sustainable design of biofuel systems: a modelling approach for the financial and environmental optimisation of first and second generation ethanol supply chains." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422062.
Le preoccupazioni crescenti degli effetti delle modificazioni climatiche e l’incertezza dell’approvvigionamento energetico esprimono l’importanza cruciale della necessità di ridefinire il sistema di approvvigionamento energetico globale. L’urgenza della questione è legata ad un disaccoppiamento tra la prospettiva di una crescita costante della domanda di combustibili, ed il loro approvvigionamento, che ci si aspetta divenire sempre più incerto e costoso. Il fenomeno del cambiamento climatico è ampiamente riconosciuto essere una conseguenza dell’accresciuta concentrazione di gas serra in atmosfera dovuti all’attività antropogenica ed il trasporto ne è uno dei principali responsabili. Negli ultimi anni, l’interesse per le energie rinnovabili è aumentato notevolmente per rispondere alla crescita della domanda di energia e cercare allo stesso tempo sia di ridurre la dipendenza da combustibili fossili che di contribuire alla mitigazione del riscaldamento globale. Alla biomassa è stata attribuita una particolare attenzione perché può essere sfruttata non solo per produrre energia elettrica, meccanica e termica, ma anche come fonte primaria di biocombustibili liquidi per autotrazione. Allo scopo di realizzare un sistema di trasporti più sostenibile, l’Unione Europea ha svolto un ruolo fondamentale nella promozione di biocombustibili fissando immissioni obbligatorie di fonti rinnovabili rispetto all’energia complessiva impiegata nei trasporti (5.75% entro il 2010 e 10% entro il 2020). I biocombustibili devono anche rispettare dei requisiti di sostenibilità ambientale nel loro impatto sul suolo, sull’acqua, sull’aria. Va tutelata, inoltre, la biodiversità e deve essere garantita una riduzione crescente delle emissioni di gas serra nella produzione di biocombustibili rispetto allo stesso quantitativo energetico di combustibile fossile che andranno a sostituire (35% dal 2009, 50% dal 2017 e 60% dal 2018). Tra le alternative possibili, il bioetanolo è generalmente considerato la soluzione più pratica e perseguibile nel breve-medio periodo per sostituire la benzina. Nonostante il suo impatto sul ciclo del carbonio (la cosiddetta carbon footprint) sia stato e sia attualmente argomento molto dibattuto, si riconosce che la produzione ed impiego di questo biocombustibile possa risultare in una riduzione netta delle emissioni di gas serra rispetto alla benzina. Questo genere di investimento su larga scala porterebbe, inoltre, una crescita delle economie rurali grazie all’aumento ed alla segmentazione dei filoni di mercato tipicamente ascritti all’agricoltura. L’attuale produzione di bioetanolo si basa sulla cosiddetta tecnologia di prima generazione, così chiamata perché sfrutta coltivazioni convenzionali come materie prime: si tratta di risorse ricche di sostanze amidacee, zuccherine od oleose, come mais, grano e canna da zucchero. Tuttavia l’iniziale entusiasmo di cui inizialmente godette questa tecnologia, si è recentemente affievolito a causa delle emergenti problematiche legate alla competizione della destinazione finale delle coltivazioni tra uso energetico ed alimentare. Inoltre, sono emerse preoccupazioni in merito al degrado ambientale per effetto di pratiche monocoltura e la deforestazione necessarie per lo sviluppo su larga scala di tale tecnologia. In generale, dubbi sulla sostenibilità energetica e sulla profittabilità economica del processo, troppo legata al costo di approvvigionamento della biomassa, hanno minato in parte lo sviluppo dell’industria del bioetanolo e la sua accettazione sociale. Alla luce di tutto questo, è emersa la convenienza a promuovere i cosiddetti biocombustibili di seconda generazione, ottenuti cioè a partire da materiale cellulosico e sostanzialmente privi di valore alimentare. Tuttavia, gli elevati costi di capitale e di produzione ostacolano attualmente lo sviluppo di tali tecnologie su scala commerciale, tanto che recentemente sono divenute operative solo strutture su scala di impianto pilota e dimostrativa. La complessità del contesto impone che la transizione verso un sistema di trasporti più sostenibile sia opportunamente guidata dall’adozione di efficaci strumenti quantitativi in grado di analizzare il problema esteso all’intera filiera produttiva (Supply Chain, SC). La ridefinizione del sistema di approvvigionamento energetico nel trasporto richiede un’analisi integrata il più comprensiva possibile delle intrecciate problematiche coinvolte nella produzione di biocombustibili. Le strategie d’investimento richiedono complessi processi decisionali, per i quali la modellazione analitica risulta essere una delle migliori opzioni metodologiche per garantire l’ottimizzazione delle scelte che coinvolgono l’intero sistema produttivo. I modelli a variabili miste lineari e intere (Mixed Integer Linear Programming, MILP), in particolare, costituiscono uno degli strumenti più adatti nel determinare le soluzioni ottimali a complessi problemi di ottimizzazione tipicamente legati alla progettazione di filiere produttive in cui vengano prese in considerazione configurazioni alternative ed esclusive. La ricerca bibliografica ha evidenziato alcune lacune nella letteratura in merito alle questioni di progettazione strategica di filiere produttive di biocombustibili, nonostante il concetto di bioraffineria costituisca già un argomento ampiamente trattato ed i biocombustibili stiano riscuotendo un interesse sempre crescente. Tutto ciò ha dato l’impulso per lo svolgimento di questa Tesi. Nel contesto generale dello sviluppo di sistemi bioenergetici, lo scopo generale di questo lavoro è quello di fornire degli opportuni strumenti decisionali per affrontare la transizione verso un sistema di trasporto più sostenibile, muovendo dalla prima alla seconda generazione di bioetanolo. Le metodologie adottate devono essere in grado di abbracciare l’intero problema analizzando tutti gli stadi della filiera, evidenziando aspetti positivi e negativi che provengono da un’ottimizzazione sia di tipo economico che ambientale. I modelli MILP proposti mirano ad essere strumenti di progettazione e pianificazione industriale nel settore dei biocombustibili in grado di contemperare aspetti economici ed ambientali. In effetti, essendo le infrastrutture produttive di biocombustibili ancora ad uno stadio immaturo, un loro studio preliminare rappresenta un’opportunità importante per analizzare la configurazione della filiera prima del suo sviluppo organico, consentendo di individuare gli investimenti ottimali e le opportune scelte di natura politica nazionale ed internazionale. Gli stadi della filiera di biocombustibili (produzione e distribuzione della biomassa; produzione e trasporto del bioetanolo) sono analizzati ed inseriti in modo integrato all’interno della modellazione matematica MILP proposta. L’attenzione è stata focalizzata in particolare sull’identificazione delle strategie opportune atte a favorire lo sviluppo delle più sostenibili tecnologie di produzione del bioetanolo. Innanzitutto, è stata considerata un’ampia gamma di processi, sia di prima che di seconda generazione, ed è stata altresì inclusa la possibilità di integrare opportunamente le due tecnologie all’interno di strutture ibride che ricevano sia materia prima amidacea che cellulosica. Infine, l’analisi si è focalizzata sull’interazione tra le politiche di mercato e lo sviluppo del mercato del bioetanolo, con particolare riguardo alle potenzialità di promuoverne una produzione sostenibile. Sono stati pertanto analizzati meccanismi di mercato cosiddetti flessibili, previsti dal Protocollo di Kyoto, come il carbon trading, ovvero lo scambio di permessi ad emettere gas serra, e potenziali effetti legati all’introduzione di sussidi pubblici. In generale, l’analisi delle filiere (Supply Chain Analysis, SCA) di biocombustibili affrontata in questo lavoro di Tesi mira a fornire una valutazione integrata di aspetti economici, finanziari ed ambientali valutati lungo l’intera rete produttiva. Questo approccio alla progettazione valuta la responsabilità ambientale come un obiettivo della modellazione e non semplicemente come vincolo, secondo l’approccio della cosiddetta Green Supply Chain Management (GrSCM). L’approccio integra i principi del Life Cycle Assessment (LCA) con le tecniche SCA per ottenere una valutazione quantitativa dell’impatto ambientale arrecato da ogni singola fase della filiera. L’analisi finanziaria inoltre necessita di essere integrata attraverso l’introduzione di opportune misure di rischio finanziario in grado di descrivere il compromesso tra profittabilità e rischio che l’investitore decide di accettare. Per affrontare queste questioni, sono introdotte tecniche di programmazione multi-obbiettivo (Multi-objective Mathematical Programming, moMP), capaci di includere aspetti ambientali, finanziari ed economici nella progettazione di processi chimici. I modelli sviluppati sono stati applicati ad un caso studio reale che affronta la possibile organizzazione della produzione di bioetanolo in Nord Italia sfruttando la disponibilità di molteplici biomasse sia di prima che di seconda generazione. Il lavoro di Tesi è organizzato secondo il seguente schema concettuale. Nel capitolo 1, dopo aver descritto il panorama bibliografico di riferimento, vengono illustrati gli approcci metodologici e modellistici alla base del lavoro, che prevedono l’integrazione di tecniche LCA ed SCA in analisi multi obiettivo secondo tecniche MILP. Nel capitolo 2 viene trattato l’approccio modellistico alla base della descrizione tecnologica e dell’analisi economica per i sistemi di produzione considerati. Vengono studiati processi di prima e seconda generazione, che ottengono bioetanolo a partire rispettivamente da materiale amidaceo (mais) e lignocellulosico (residui e biomasse coltivate a scopo energetico, energy crops). L’aspetto peculiare della trattazione riguarda, inoltre, la modellazione di un processo di tecnologie ibride che utilizzano sia la parte amidacea che il residuo cellulosico del mais per la produzione di biocombustibili. Nel capitolo 3 viene condotta la progettazione di filiera di bioetanolo attraverso la formulazione di un problema di ottimizzazione bi-obbiettivo (simultanea minimizzazione delle emissioni di gas serra e massimizzazione del profitto) con lo sviluppo di un modello MILP multi-periodo e georeferenziato. Il modello MILP formulato sfrutta tecniche moMP per l’implementazione di criteri di ottimizzazione ambientale ed economico. Sono considerate diverse configurazioni tecnologiche e vengono prese in esame più soluzioni per lo sfruttamento dei sotto-prodotti del processo di produzione di bioetanolo come possibili alternative tecnologiche per l’abbattimento di costi ed emissioni. Il modello costruito viene poi applicato all’analisi di una possibile filiera di bioetanolo in Nord Italia. Nel capitolo 4 si studiano gli effetti dell’applicazione di strumenti finanziari sul design di filiere bioenergetiche nelle loro capacità di promuovere tecnologie più sostenibili per la produzione di bioetanolo. Nel modello viene implementato un meccanismo di carbon trading che prevede la commercializzazione di permessi ad emettere gas serra (CO2-equivalenti) rispetto a dei valori soglia stabiliti secondo la normativa ambientale per la sostenibilità dei biocombustibili. La trattazione modellistica esamina anche le dinamiche dei fattori d’incertezza del mercato di riferimento con particolare riguardo all’acquisto della biomassa utilizzata. In questo caso, sono stati ignorati gli aspetti legati alla georeferenziazione, per esaltare invece la questione rilevante legata alla scelta tecnologica sulle prestazioni della filiera. Si descrive, pertanto, lo sviluppo di un modello MILP multi-periodo con un approccio stocastico per la pianificazione della produzione di bioetanolo. La filiera viene progettata seguendo l’ottimizzazione di indici finanziari di investimento nel quale un ulteriore termine di profitto/perdita proviene dalla commercializzazione di permessi di emissione. Il capitolo 5 estende la trattazione del modello descritto nel capitolo 4, inglobando una più ampia modellazione della pianificazione d’investimento in condizioni di incertezza che abbraccia il processo decisionale con considerazioni di gestione del rischio d’investimento. In particolare, il modello MILP stocastico viene esteso secondo una formulazione multi-obbiettivo permettendo la simultanea ottimizzazione di profitto ed emissione di gas serra. Sono inoltre inclusi dei vincoli sul livello massimo di rischio finanziario sostenibile nell’investimento. Si mostra in questo modo come la diversa attitudine al rischio dell’investitore (propensione o avversione) modifichi la strategia d’investimento in termini di scelte tecnologiche e biomasse trattate, anche alla luce di vincoli ambientali e di profittabilità economica. Il capitolo 6 conclude la discussione della ricerca sviluppata con la presentazione dei principali risultati conseguiti e l’analisi di alcuni dei potenziali sviluppi futuri per proseguire la ricerca sull’argomento
Zakaria, Rabih. "Optimization of the car relocation operations in one-way carsharing systems." Thesis, Belfort-Montbéliard, 2015. http://www.theses.fr/2015BELF0281/document.
To buy it. Users can have access to vehicles on the go with or without reservation. Each station has a maximumnumber of parking places. In one-way carsharing system, users can pick up a car from a station and drop it in anyother station. The number of available cars in each station will vary based on the departure and the arrival of cars oneach station at each time of the day. The demand for taking or returning cars in each station is often asymmetric andis fluctuating during the day. Therefore, some stations will accumulate cars and will reach their maximum capacitypreventing new arriving cars from finding a parking place, while other stations will become empty which lead to therejection of new users demand to take a car. Users expect that cars are always available in stations when they needit, and they expect to find a free parking place at the destination station when they want to return the rented car aswell. However, maintaining this level of service is not an easy task. For this sake, carsharing operators recruitemployees to relocate cars between the stations in order to satisfy the users' demands.Our work concerns the optimization of the car relocation operations in order to efficiently redistribute the cars overthe stations with regard to user demands, which are time and space dependent. In one-way carsharing systems, therelocation problem is technically more difficult than the relocation problem in bikesharing systems. In the latter, wecan use trucks to move several bikes at the same time, while we cannot do this in carsharing system because of thesize of cars and the difficulty of loading and unloading cars. These operations increase the cost of operating thecarsharing system.As a result, optimizing these operations is crucial in order to reduce the cost of the operator. In this thesis, we modelthis problem as an Integer Linear Programming model. Then we present three different car relocation policies thatwe implement in a greedy search algorithm. The comparison between the three policies shows that car relocationoperations that do not consider future demands are not effective in reducing the number of rejected demands.Results prove that solutions provided by our greedy algorithm when using a good policy, are competitive withCPLEX solutions. Furthermore, adding stochastic modification on the input data proves that the robustness of thetwo presented approaches to solve the relocation problem is highly dependent on the input demand even afteradding threshold values constraints. After that, the analysis of variance (ANOVA) and the multi-linear regressionmethods were applied on the used dataset in order to build a global model to estimate the number of rejecteddemands. Finally, we developed and compared two multi-objectives evolutionary algorithms to deal with thedecisional aspect of the car relocation problem using NSGA-II and memetic algorithms
Zamboni, Andrea. "SUPPLY CHAIN MODELLING FOR THE ECONOMIC AND LIFE CYCLE ANALYSIS AND OPTIMISATION OF BIOETHANOL FIRST-GENERATION PRODUCTION PROCESSES." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426913.
Gli ultimi due decenni sono stati caratterizzati da profondi cambiamenti negli equilibri economici e geopolitici mondiali. Uno dei motori di questa trasformazione è stata sicuramente la crisi del sistema di approvvigionamento energetico globale, di cui riscaldamento globale e carenza di petrolio sono solo due delle molteplici sfaccettature. Il cuore della questione può essere riassunto da una dichiarazione dello Sceicco Ahmad Zaki Yamani (all’epoca presidente dell’OPEC), il quale, circa trent’anni fa, asserì che “l’Era della pietra non finì per la mancanza di pietra, così come l’Era del petrolio finirà molto prima che il mondo esaurisca il petrolio”. La vera domanda, quindi, non è tanto quando il petrolio terminerà, ma in che termini agire nell’interpretare e guidare il profondo cambiamento in atto. Tutto ciò ha generato in tutto il mondo un acceso dibattito per stabilire quale fosse la via migliore per gestire la rivoluzione del settore energetico mondiale e individuare quelle risorse di energia rinnovabile in grado di rappresentare l’alternativa più plausibile al sistema di approvvigionamento tradizionale. Tra queste, l’utilizzo della biomassa per la produzione di combustibili liquidi è stata universalmente indicata come la miglior alternativa ai vettori fossili comunemente utilizzati nel settore dei trasporti. Recentemente, la Commissione Europea ha assunto un ruolo determinante nell’incoraggiare gli Stati Membri all’adozione di programmi ambiziosi volti alla promozione dell’utilizzo di combustibili alternativi: questo si è tradotto in politiche di vario tipo, caratterizzate da un’immissione obbligatoria sul mercato di quote sempre maggiori di combustibili prodotti da biomassa. Standard europei ne regolano la qualità in modo da garantire il perseguimento degli obiettivi energetici e ambientali comunitari. In particolare, un requisito fondamentale è la capacità di riduzione delle emissioni del 35% rispetto alla produzione dello stesso quantitativo energetico di combustibile fossile che andranno a sostituire. Tra le alternative possibili, il bioetanolo è generalmente considerato la soluzione più pratica e perseguibile (almeno in un’ottica di breve-medio periodo) per sostituire la benzina convenzionale. Nonostante alcuni evidenti vantaggi, vi sono, tuttavia, una serie di questioni di tipo economico, ambientale e di accettazione sociale che ne hanno sinora rallentato l’effettiva penetrazione nel mercato dei carburanti per autotrazione. Il nocciolo della questione è il dubbio se effettivamente il bioetanolo sia in grado di fornire la giusta risposta alle esigenze di sicurezza di approvvigionamento imposte dalla questione energetica. La risposta a questa questione impone l’adozione di strumenti quantitativi in grado di valutare le reali prestazioni del sistema di produzione. In particolare, questi strumenti dovrebbero essere pensati per fornire supporto tecnico a livello politico e manageriale per gestire e progettare i nuovi sistemi di produzione di biocombustibili. Tali strumenti richiedono l’adozione di un approccio più esteso al problema che sia quindi in grado di estendere l’analisi all’intera filiera produttiva (Supply Chain, SC). La ricerca bibliografica ha evidenziato evidenti lacune in materia di progettazione strategica di infrastrutture produttive per biocombustibili e, in particolare, in termini di metodologie quantitative per affrontare il problema. Il progetto di ricerca discusso in questa Dissertazione ha avuto come obiettivo quello di coprire questa lacuna e sviluppare una metodologia originale per l’accoppiamento di gestione delle SC (Supply Chain Management, SCM) e programmazione matematica. Il lavoro si è focalizzato sulla definizione di modelli a variabili miste lineari e intere (Mixed-Integer Linear Programming, MILP) per l’analisi di sistemi produttivi per il bioetanolo di prima generazione, in grado di essere utilizzati come efficaci strumenti di supporto alle politiche decisionali in materia di biocombustibili. L’obiettivo finale è quello di realizzare uno strumento di progettazione e pianificazione industriale basato sui comuni approcci alla progettazione strategica di filiere produttive, secondo criteri di tipo economico, finanziario e ambientale. I modelli MILP sono stati sviluppati e utilizzati per descrivere e ottimizzare la gestione delle fasi di lavorazione agricola per la produzione di biomassa, la strategia di approvvigionamento della stessa (produzione autarchica o importazione), la locazione e le dimensioni dei siti di produzione (di biomassa e biocombustibile), la distribuzione logistica e la tipologia del sistema di trasporti. Inoltre, la costruzione dei modelli è stata basata su una georeferenziazione delle variabili di progetto. Una formulazione di tipo stocastico è stata incorporata per gestire l’effetto dell’incertezza delle condizioni di mercato sulle prestazioni finanziarie. Infine, è stato approfondito un aspetto relativo all’impatto ambientale delle fasi agricole della catena produttiva così da minimizzare le emissioni di gas serra derivanti dall’impiego di fertilizzanti azotati. Gli aspetti economici dell’infrastruttura produttiva sono stati valutati mediante approcci di analisi della filiera di produzione (Supply Chain Analysis, SCA), mentre le prestazioni ambientali del ciclo produttivo sono state stimate attraverso un approccio di analisi del ciclo di vita (Life Cycle Analysis, LCA) di tipo Well-to-Tank (WTT). I modelli sviluppati sono stati applicati per studiare la possibile organizzazione della produzione di bioetanolo da mais in Nord Italia. La struttura della Tesi esposta segue lo schema logico seguente. Nel primo Capitolo sono presentate le basi bibliografiche del progetto di ricerca. Partendo dall’analisi delle problematiche principali che riguardano le recente crisi del sistema di approvvigionamento energetico globale, il lettore è accompagnato attraverso un percorso che porta alla descrizione delle principali soluzioni prospettate per risolvere il problema in un contesto più specifico, che è quello del settore dei trasporti. In particolare, la produzione di biocombustibili viene analizzata ponendo particolare attenzione al bilancio tra pro e contro emersi nel valutare le sue effettive potenzialità nel sostituire la produzione di combustibili tradizionali. Si passa poi ad un’analisi bibliografica focalizzata sulla produzione di bioetanolo mediante tecnologie di prima generazione, volta a porre in luce i principali problemi da affrontare al fine di realizzare gli obiettivi europei in materia di biocombustibili. Il Capitolo 2 è dedicato alla descrizione dello stato dell’arte della programmazione matematica e a fornire una base teorica per la formulazione di modelli di ottimizzazione di SC. Sono qui presentati gli approcci algoritmici al SCM, dando un rilievo particolare alla formulazione matematica di modelli di tipo MILP e alla costruzione logica degli algoritmi di soluzione. Infine, sono approfondite alcune tecniche specifiche come la programmazione matematica multi-obiettivo (Multi-objective Mathematical Programming, MoMP) e l’ottimizzazione di tipo stocastico. Il Capitolo 3 conclude la parte introduttiva della Dissertazione. In questo Capitolo, infatti, sono dichiarate le principali ipotesi relative al modo di affrontare sia la progettazione dei sistemi di biocombustibili, sia la costruzione dei modelli matematici per l’ottimizzazione degli stessi. Viene presentata una descrizione generale delle principali componenti della catena produttiva di bioetanolo e sono discussi i criteri di valutazione economica e ambientale dei nodi della filiera. Il riferimento è il caso reale considerato in questo studio, ovvero la produzione di bioetanolo da mais in Nord Italia. Nel Capitolo 4 si affronta il primo problema di progettazione. Questo prevede lo sviluppo di un modello MILP stazionario e georeferenziato per la progettazione strategica di SC di bioetanolo secondo un criterio di minimizzazione dei costi operativi. Vengono descritti i principali problemi legati alla progettazione del sistema e la formulazione matematica proposta per il modello di ottimizzazione. Il modello costruito viene poi applicato all’analisi del caso studio reale descritto al Capitolo 3. Il Capitolo 5 tratta lo sviluppo di modelli di ottimizzazione ambientale. Il modello MILP descritto nel Capitolo 4 è preso come base per l’implementazione di criteri di ottimizzazione ambientale considerati contemporaneamente a quelli di tipo economico attraverso tecniche MoMP. Sono prese in considerazione differenti soluzioni per lo sfruttamento dei sotto-prodotti del processo di produzione di bioetanolo come possibili alternative tecnologiche per l’abbattimento di costi ed emissioni. Nel Capitolo 6 viene presentato un ulteriore sviluppo del modello al fine di renderlo adatto alla pianificazione degli investimenti a lungo termine e a gestire il rischio d’investimento dovuto all’incertezza delle condizioni di mercato. Si descrive, pertanto, lo sviluppo di un modello MILP di tipo dinamico e stocastico per l’analisi finanziaria e la riduzione del rischio d’investimento nella pianificazione della produzione di bioetanolo. L’implementazione al caso studio si focalizza sull’analisi delle dinamiche di mercato con riferimento ai costi d’acquisto della biomassa e ai prezzi di vendita di etanolo e sottoprodotti. Il Capitolo 7 descrive lo sviluppo di un ulteriore modello matematico per il miglioramento delle prestazioni ambientali del sistema produttivo in esame, al fine di allinearne le performance agli standard europei in materia di emissioni di gas serra. Un modello di tipo MILP è concepito per l’ottimizzazione delle pratiche agricole (in particolare dell’utilizzo di fertilizzanti azotati) e delle tecnologie di sfruttamento dei sottoprodotti secondo criteri di tipo ambientale e finanziario. Il modello sviluppato è applicato per la massimizzazione del profitto e la minimizzazione delle emissioni di gas serra della produzione di etanolo da mais. Il Capitolo 8 conclude la discussione della ricerca sviluppata con la presentazione dei principali risultati conseguiti e l’analisi di alcuni dei potenziali sviluppi futuri per proseguire la ricerca sull’argomento.
Etheve, Marc. "Solving repeated optimization problems by Machine Learning." Thesis, Paris, HESAM, 2021. http://www.theses.fr/2021HESAC040.
This thesis aims at using machine learning techniques in the context of Mixed Integer LinearProgramming instances generated by stochastic data. Rather than solve these instances independentlyusing the Branch and Bound algorithm (B&B), we propose to leverage the similarities between instancesby learning inner strategies of this algorithm, such as node selection and branching.The main approach developed in this work is to use reinforcement learning to discover by trials-and-errorsstrategies which minimize the B&B tree size. To properly adapt to the B&B environment, we definea new kind of tree-based transitions, and elaborate on different cost models in the correspondingMarkov Decision Processes. We prove the optimality of the unitary cost model under both classical andtree-based transitions, either for branching or node selection. However, we experimentally show that itmay be beneficial to bias the cost so as to improve the learning stability. Regarding node selection, weformally exhibit an optimal strategy which can be more efficiently learnt directly by supervised learning.In addition, we propose to exploit the structure of the studied problems. To this end, we propose adecomposition-coordination methodology, a branching heuristic based on a graph representation of aB&B node and finally an approach for learning to disrupt the objective function
Ju, Min. "Optimisation de la protection des réseaux optiques de nouvelle génération." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0226/document.
Network survivability is a critical issue for optical networks to maintain resilience against network failures. This dissertation addresses several survivability design issues against single link failure and large-scale disaster failure in optical networks. Twoclassic protection schemes, namely pre-configured Cycles (p-Cycle) protection and path protection, are studied to achieve high protection capacity efficiency while taking intoaccount the equipment cost, power consumption and resource usage. These survivable network design problems are first formulated by mathematical models and then offered scalable solutions by heuristic algorithms or a decomposition approach.We first consider single link failure scenario. To cut the multi-line rates transponderscost in survivable Mixed-Line-Rate (MLR) optical networks, a distance-adaptive andlow Capital Expenditures (CAPEX) cost p-cycle protection scheme is proposed withoutcandidate cycle enumeration. Specifically, path-length-limited p-cycles are designed touse appropriate line rate depending on the transponder cost and transmission reach.A Mixed Integer Linear Programming (MILP) model is formulated to directly generate the optimal p-cycles with the minimum CAPEX cost. Additionally, Graph Partitioning in Average (GPA) algorithm and Estimation of cycle numbers (EI) algorithm are developed to make the proposed MILP model scalable, which are shown to be efficient.Regarding the power consumption in survivable Elastic Optical Networks (EONs),power-efficient directed p-cycle protection scheme for asymmetric traffic is proposed.Owing to the advantage of distinguishing traffic amount in two directions, directedp-cycles consume low power by allocating different Frequency Slots (FSs) and modulation formats for each direction. An MILP model is formulated to minimize total power consumption under constraints of directed cycle generation, spectrum assignment,modulation adaptation and protection capacity allocation. To increase the scalability, the MILP model is decomposed into an improved cycle enumeration and a simplified Integer Linear Programming (ILP) model. We have shown that the directedp-cycles out perform the undirected p-cycles in terms of power consumption and spectrum usage.In order to improve the spectrum usage efficiency in p-cycle protection, a SpectrumShared p-cycle (SS-p-cycle) protection is proposed for survivable EONs with and without spectrum conversion. SS-p-cycles permit to reduce spectrum usage and Spectrum Fragmentation Ratio (SFR) by leveraging potential spectrum sharing among multiplep-cycles that have common link(s). The ILP formulations are designed in both cases of with and without spectrum conversion to minimize the spectrum usage of SS-p-cycleswhich can obtain the optimal solution in small instance, and a time-efficient heuristic algorithm is developed to solve large-scale instances. Simulation results show that SSp-cycles have significant advantages on both spectrum allocation and defragmentation efficiency, and the spectrum conversion does help SS-p-cycle design to acquire better spectrum utilization
Pirogov, Aleksandr. "Equilibrage robuste de lignes de production : modèles de programmation linéaire en variables mixtes et règles de pré-traitement." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2019. http://www.theses.fr/2019IMTA0158/document.
This work deals with a robust optimisation of production lines at the design stage. The design of such lines can be interpreted as an optimisation problem that consists in finding a configuration optimising individual objectives and respecting technological and economic constraints. We conside rtwo types of production lines: assembly and transfer lines. The first one can be represented as a set of linearly ordered stations where the tasks are executed sequentially. The second one is composed of transfer machines, including several multispindle heads. All tasks within a single head are executed simultaneously, while tools on a machine work in a sequential mode. We describe different approaches for modelling the uncertainty of data in line balancing problems. Our objective is to identify the approaches that best fit the context of the design. In particular, the attention concentrates on the robust approach. We propose a new optimisation criterion based on the stability radius of a feasible solution. Then, robust formulations are presented for the design of the assembly and transfer lines under variations of task processing times. We also develop heuristic methods whose results are used to improve mathematical models. Finally, a new hybrid resolution method is elaborated to solve different variants of the stability radius maximisation
Pajot, Camille. "OMEGAlpes : outil d’aide à la décision pour une planification énergétique multi-fluides optimale à l’échelle des quartiers." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT042.
Mostly responsible for climate change, the energy sector is particularly targeted and energy transition policies are emerging, based on the principles of sobriety, efficiency and low-carbon energy production. Energy systems need to adapt quickly to these changes and be designed to consider a multi-energy approach and demand-side management strategies. In this context, this thesis proposes to develop a methodology and an associated decision support tool OMEGAlpes, offering the different energy actors an aid to design, size, and manage energy systems at the district level. First, an optimal energy planning approach will be developed. A methodology, based on power balances will then be presented, to treat generically study cases about energy planning at the district scale, and then illustrated on a case of wasted heat recycling. Consumption models based on statistical approaches will then be used to represent temporal flexibility scenarios (load shifting). An alternative to this data approach, based on the physical modeling of buildings, will then be presented through the use of reduced thermal models. Finally, all of these models will be capitalized within an automatic generation tool for optimization models, based on a methodology for building energy models from generic elements. The development of this open source tool, in Python language, and the principle of automatic generation of models will finally be detailed
Rahmouni, Mouna. "Optimisation combinée des approvisionnements et du transport dans une chaine logistique." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4329.
The proposed joint delivery problem (JDP) is a delivery tour planning problem on a time horizon decomposed into elementary periods or rounds, the time horizon being the common delivery period for all products. The data of these parameters provides a linear formulation of the problem, with binary decision variables. The model also incorporates the constraints of meeting demand from stock and the quantities supplied, storage and transport capacity constraints.In order to also solve the problem of choice of delivery rounds, it is necessary to introduce in the model several constraints and variables related to the sites visited during each round. It is proposed to solve the problem in two steps. The first step is the calculation of the minimum off-line cost of the tour associated with each subset of sites. One can observe that for any given subset of sites, the optimal Hamiltonian cycle linking those sites to the warehouse can be calculated in advance by a traveling salesman problem algorithm (TSP). The goal here is not to fully analyze the TSP, but rather to integrate its solution in the formulation of the JRP. In the second stage, binary variables are associated with each subset and each period to determine the selected subset of sites in each period and its associated fixed cost
Ait, Ouahmed Mohammed Amine. "Optimisation dans l'auto-partage à un seul sens avec voitures électriques et relocalisations." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0228/document.
This thesis aims at modelling and solving optimization problems related to the management of one-way-electric-car-sharing systems, where users can take a car from a station, use it, and then return it to another station. This generally leads to an imbalanced distribution of cars, with some full stations and other empty ones. A solution to this problem, implemented by car-sharing operators, is to employ staff agents to move cars as needed. However, identifying this need is a non-trivial optimization problem, especially since the system may be more constrained when the vehicles used are electric, which generates battery recharging and autonomy constraints. The global optimization problem addressed is then divided into two sub-problems. The first one is assigning the cars to customers, as well as their routing; it is denoted by ROCSP (Recharging OneWay Car Sharing Problem). The second problem involves agents planning and routing; it is denoted by ESRP (Employee Scheduling Routing Problem). 1. For the ROCSP, we propose two Mixed-integer linear programming (MILP) modelizations of the problem: One based on flows and the other based on paths. This means that the two models include the battery-recharging constraints in two different ways. As the exact resolution through the MILP models is quite expensive in terms of computational time and is not adapted for the resolution of real-size car-sharing instances, we introduce heuristics that enable the optimization of cars-redistribution and service management of the service within a reasonable amount of time. These heuristics allows the calculation of the number of cars and the various redistribution operations to be performed on a given day. 2. For the ESRP, this second problem is also addressed with MILP models for the exact resolution, and some heuristics are suggested for an approximate resolution. This process has reasonable calculation time and aims at finding the minimum number of agents to perform the necessary relocation operations that stem from the first problem, namely, the ROCSP. Once the ROCSP and ESRP solved in their static versions, we then focus on the ROCSP by exploring another variant of the problem : ROCSP with dynamic reservation. We also suggest to explore a new concept : Auto-CoPartage, which is a hybridization of car-sharing and carpooling. The stated algorithms are validated on the Auto Bleue electrical vehicles fleet in the network of the city of Nice, essentially by relying on flow generation models to estimate the demand, but also using other instances that we have generated for other cities. All the data are handled using a Geographical Information System
Cardozo, Arteaga Carmen. "Optimisation of power system security with high share of variable renewables : Consideration of the primary reserve deployment dynamics on a Frequency Constrained Unit Commitment model." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC024/document.
The Unit Commitment problem (UC) is a family of optimisation models for determining the optimal short-term generation schedule to supply electric power demand with a defined risk level. The UC objective function is given by the operational costs over the optimisation horizon. The constraints include, among others, technical, operational and security limits. Traditionally, the security constraints are given by the requirement of a certain volume of on-line spare capacity, which is called the reserve and is meant to handle uncertainty, while preventing the interruption of power supply. It is commonly specified following a static reliability criterion, such as the N-1 rule.Nevertheless, in small systems the fixed, and a priori defined, reserve constraint could entail a violation of the N-1 criterion, although the reserve constraint was met. More recently, the increasing share of variable generation from renewable sources (V-RES), such as wind and solar, may lead to UC solutions that no longer ensure system security. Therefore, different impact mitigation techniques have been proposed in literature, which include the revision of UC models to provide a better representation of the system dynamics. This subfamily of UC models is formally defined in this work as the frequency constrained UC problem (FCUC), and aims to keep the frequency above a certain threshold, following pre-defined contingencies, by adding enhanced security constraints. In this work this topic is addressed in four parts.The first part identifies the main challenge of formulating the FCUC problem. Indeed, the frequency minimum, also called the frequency nadir, constraint is strongly non-linear on the decision variables of the UC model. Moreover, the behaviour of the frequency nadir regarding the binary decision variables is hard to approximate by analytical functions. Thus, a sequential simulation approach is proposed, based on a classic UC model and a reduced order model of the primary frequency response. The potential benefits of a smarter allocation of the primary reserve is revealed.The second part of this work investigates the impact of V-RES sources on the primary frequency response. The underlying processes that lead to the increase of the Under-Frequency Load Shedding (UFLS) risk are thoroughly discussed. The need of formulating more accurate FCUC models is highlighted.The third part of this work examines the cost/benefit and limitation of FCUC models based on indirect constraints over certain dynamic parameters of the generating units. A methodology is proposed that assesses the effectiveness and optimality of some existing V-RES impact mitigation techniques, such as the increase of the primary reserve requirement, the prescription of an inertia requirement, the authorisation of V-RES dispatch-down or the consideration of fast non-synchronous providers of frequency regulation services. This study showed the need for new methods to properly handle the frequency nadir constraint in order to ensure optimality, without compromising the optimisation problem’s tractability.The fourth part of this work offers a new formulation of the FCUC problem following a Bender’s decomposition approach. This method is based on the decomposition of an optimisation problem into two stages: the master and the slave problems. Here, the master problem deals with the generating unit states and the slave problem handles the frequency nadir constraints through a cutting plane model. Simulation results showed that the more accurate representation of the frequency nadir in the slave problem reduces the risk of UFLS and the security cost, with respect to other FCUC models, such as those based on inertia constraints. In addition, the optimality of the global solution is guaranteed; although the convergence of the master problem is slow, due to the well-known tailing off effect of cutting plane methods
Kindesjö, Viktoria, and Linda Nordqvist. "Energirenovering av flerbostadshus från miljonprogrammet genom LCC-optimering : En fallstudie av två byggnader i Linköping, Sverige." Thesis, Linköpings universitet, Energisystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158098.
Ghazouani, Sami. "Modèles linéaires d’optimisation pour la conception simultanée de réseaux de matière et de chaleur d'un écoparc industriel." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM060/document.
The design of industrial processes needs to be adapted as cheap natural resources are scarcer and environmental standards are more stringent to limit their environmental footprints. In order to improve their cost-effectiveness as well as their sustainability, industrial effluents must considered as potential heat and mass resources whether they are recycled locally or at a larger scale by sharing them with other industrial companies; thus forming an eco-industrial park (EIP).This thesis presents a new systemic and systematic approach to design optimal mass allocation and heat exchanger networks simultaneously. Three linear models of incremental complexity have been developed to design optimal recovery networks at a local scale. The first linear model (M1) looks for the necessary minimum fresh resource consumption. The second linear model (M2) presents a new superstructure that allows optimizing mass and heat requirements simultaneously, targeting the minimum annual operating costs. The third linear model (M3) allows designing optimal mass allocation and heat exchanger networks simultaneously. Its objective function is the total annualized cost considering operating and capital costs.The opportunity to use regeneration units is added to the structure of the three previous models. Any type of these units can be represented by a simple model with the generic parameters based on objects already existing in the previous models formulations.Finally, a M3 model applicability is extended to the design of collaborative eco-industrial parks with additional concepts (sites, clusters, indirect heat and mass networks) to obtain a new M4 model. In this model, the capital costs related to the topology of the networks are taken into account in the objective function.The relevance and performances of the proposed models are validated with several case studies taken from the literature
Beeker-Adda, Nathanaël. "Modélisation et contrôle des ballons d'eau chaude sanitaire à effet Joule : du ballon individuel au parc." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM031/document.
This thesis focuses on the development of advanced strategies for load shifting of large groups of electric hot water tanks (EHWT).The first part of this thesis is dedicated to representing an EHWT as an input-output system. The idea is to design a simple, tractable and relatively accurate model that can be implemented inside a low-power computing unit embedded in a smart EHWT, for practical applications of optimization strategies. It includes in particular a phenomenological multi-period model of the temperature profile in the tank and a realistic domestic hot water consumption model.The second part focuses on the design of optimal control strategies for a group of tanks. Three use-cases are studied. The first one deals with a small number of smart and controllable EHWT for which we propose a discrete-time optimal resolution method. The second use-case adresses a medium-scale group of controllable tanks and proposes a heuristic which keeps the heating period undivided to minimize thermo-hydraulic hazards. Finally, we present the modelling of the behavior of a infinite population of tanks under the form of a Fokker-Planck equation
Malyutin, Sergey. "Algorithms and Software for Decision Support in Design of Assembly and Transfer Lines." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM020/document.
An overview of existing problems and methods for the design of assembly and transfer lines is given. A new workforce assignment problem for a paced multi-product assembly line with a goal of minimizing the number of workers is studied. Various precedence relations between operations and functions of operation processing times dependent on the number of workers areconsidered. A new problem of multi-objective optimization for a single product transfer line is solved. Several exact and heuristic methods and their computer implementations for both problems are developed by the author. An application of developed approaches to solving a real production problem relevant to the European project amePLM is demonstrated
Sowgath, Md Tanvir, and Iqbal M. Mujtaba. "Optimisation of design and operation of MSF desalination process using MINLP technique in gPROMS." 2008. http://hdl.handle.net/10454/10982.
Optimal design and operation of MSF desalination process is considered here using MINLP technique within gPROMS model builder 2.3.4. gPROMS provides an easy and flexible platform to build a process flowsheet graphically and the corresponding master model connecting automatically individual unit model equations during simulation and optimisation. For different freshwater demand throughout the year and with seasonal variation of seawater temperature, the total annualised cost of desalination is minimised. It is found that seasonal variation in seawater temperature results in significant variation in design and some of the operating parameters but with minimum variation in of process temperatures. The results also reveal the possibility of designing stand-alone flash stages which would offer flexible scheduling in terms of the connection of various units (to build up the process) and efficient maintenance of the units throughout the year as the weather condition changes. In addition, operation at low temperatures throughout the year will reduce design and operating costs in terms of low temperature materials of construction and reduced amount of anti-scaling and anti-corrosion agents.
Sowgath, Md Tanvir, and Iqbal M. Mujtaba. "Optimisation of MSF Desalination Process for Fixed Water Demand using gPROMS." 2007. http://hdl.handle.net/10454/10691.
Simultaneous optimisation of design and operating parameters of MSF desalination process is considered here using MINLP technique within gPROMS software. For a fixed fresh water demand throughout the year and with seasonal variation of seawater temperature, the external heat input (a measure of operating cost) to the process is minimised. It is observed that seasonal variation in seawater temperature results in significant variation in design with minimum variation in operating conditions in terms of process temperatures. The results also reveal the possibility of designing stand-alone flash stages which would offer flexible scheduling in terms of the connection of various units (to build up the process) and efficient maintenance of the units throughout the year as the weather condition changes. In addition, operation at low temperatures throughout the year will reduce design and operating costs in terms of low temperature materials of construction and reduced amount of antiscaling and anti-corrosion agents.
(7047464), Taotao He. "New relaxations for composite functions." Thesis, 2019.