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Kloninger, Paul. "MDO-Simulation eines Rutschreifens auf GFK-Wasserrutschen." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-206945.
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Die Option Mechanism Dynamics (MDO) von Creo Parametric ist ein Tool aus dem Bereich Starrkörperdynamik. Im Kern des Vortrags steht jedoch die MDO-Funktion 3D-Kontakt, die einzigartig mit elastischen Körpern arbeitet.
Im Vortrag wird die Vorgehensweise bei der dynamischen Simulation eines Rutschreifens auf GFK-Wasserrutschen erläutert, abschließend werden Animationsbeispiele präsentiert.
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Gantois, K. "An MDO concept for large civil airliner wings." Thesis, Online version, 1998. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.266980.
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Hiriyannaiah, Santosh. "Enhancement of information management capabilities in MDO framework." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1220473735/.
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Dasgupta, Amlan. "Addition of Features to an Existing MDO Model for Containerships." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33351.
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Traditionally, the â Design Spiralâ is used for the design of ships. The design spiral endorses the concept that the design process is sequential and iterative. Though this procedure was very effective over the years, the current trend of engineering demands that more stress be put on the exploration of optimum design. With the advancement of computing technologies, the onus has shifted from finding better calculation schemes to formulating an economically viable design scheme. One of the objects of the FIRST project funded by MARITECH was to develop a computer tool to give the best ship design using optimization techniques. This was entrusted to the Department of Aerospace and Ocean Engineering at Virginia Polytechnic Institute and State University in Blacksburg, Virginia. A container ship was chosen as the test case. The problem was tackled from an ownerâ s point of view. Hence, the required freight rate was chosen as the objective.
To achieve that goal, the team developed a package that consists of three modules: optimization, geometric and a performance evaluation module. Though these modules are essentially independent, the user has control over an overall manager. He can change the initial value of design parameters, set bounds and vary constraint bounds as per his needs. Though he does not know what goes on behind the user interface, he still feels secure with the design process because he has overall control. This sense of security breaks down when he has access to limited variables and constraints.
A prototype MDO tool is developed based on Microsoftâ s COM framework using ATL. With this design, the modules can be modified with minimum programming effort. The user interface gives the user flexibility to manipulate relevant parameters that affect the design. A geometric shape manipulation scheme is developed in which the hull form was generated by blending two hull forms. This MDO tool is used to design a container ship with the required freight rate as the objective to be minimized. It is noticed that without a structural constraint, the design tends towards one with maximum length and beam. This led to unreasonably large ratios of B/D and L/D.
A B/D constraint is applied to the design to get a better structural design. Results with this constraint enabled have pointed in the direction of adding two other design variables. This constraint increases the depth of the ship. With the increase in depth, the center of gravity of the ship also rises decreasing the GM of the ship. This lowering of GM adversely affects the GM constraint. The number of tiers on deck (NTd) is made a design variable to enable the optimizer to have the flexibility of manipulating the cargo carrying capacity. It was noticed that the ship is unable to have a high NTd because of the violation of the GM constraint. Hence, ballast has also been added as a design variable to reduce the center of gravity of the ship increasing the GM of the ship. This feature enables the optimizer to carry greater cargo on deck improving the objective function.
An effort is made to analyze the efficacy of the MDO tool by varying various parameters that affect the design. Technology factors have been introduced which give an insight on effect of key parameters. They also reflect on future design trends. Three evaluation tools: sensitivity analysis, alpha plots and restart option have been incorporated in the design process to gauge the results of optimization.
The effect of another structural constraint L/D was also investigated. This constraint tends to bring down the overall length and is inconclusive in its results. Further analysis of this constraint is needed to draw usable conclusions. The linear response surface approximation was eliminated and the original stepwise discontinuous TEU capacity function is employed in the later examples. It was found that the minimum of the required fright rate occurred at the lower limits of length and beam on each TEU capacity platform. A systematic search of TEU plateaus in the vicinity of the primary optimum was necessary to define the secondary optimumMaster of Science
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Chen, Ying. "Formulation of a Multi-Disciplinary Design Optimization of Containerships." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/36069.
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To develop a computer tool that will give the best ship design using an optimization technique is one of the objects of the FIRST project. Choosing a containership design as a test case, the Design Optimization Tools (DOT) package is used as the optimization tool. The problem is tackled from the ship owner's point of view. The required freight rate is chosen as the objective function because the most important thing that concerns the ship owner is whether the ship will make a profit or not, and if so, how much profit it can make. DOT, as well as any other numerical optimization tool, only gives an approximation of the optimum design and uses numerical approximation during the optimization. It is very important for the users to formulate carefully the optimization problem so that it will give a stable and reasonable solution. Development of a geometric module and choosing suitable empirical formulas for performance evaluation are also major issues of the project.Master of Science
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Knill, Duane L. "Implementing Aerodynamic Predictions from Computational Fluid Dynamics in Multidisciplinary Design Optimization of a High-Speed Civil Transport." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/29530.
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A method to efficiently introduce supersonic drag predictions from computational fluid dynamics (CFD) calculations in a combined aerodynamic-structural optimization of a High-Speed Civil Transport (HSCT) is presented. To achieve this goal, the method must alleviate the large computational burden associated with performing CFD analyses and reduce the numerical noise present in the analyses. This is accomplished through the use of response surface (RS) methodologies, a variation of the variable-complexity modeling (VCM) technique, and coarse grained parallel computing. Variable-complexity modeling allows one to take advantage of the information gained from inexpensive lower fidelity models while maintaining the accuracy of the more expensive high fidelity methods. The utility of the method is demonstrated on HSCT design problems of five, ten, fifteen, and twenty design variables.
Motivation for including CFD predictions into the HSCT optimization comes from studies detailing the differences in supersonic aerodynamic predictions from linear theory, Euler, and parabolized Navier-Stokes (PNS) calculations for HSCT configurations. The effects of these differences in integrated forces and distributed loads on the aircraft performance and structural weight are investigated. These studies indicate that CFD drag solutions are required for accurate HSCT performance and weight estimates.
Response surface models are also used to provide useful information to the designer with minimal computational effort. Investigations into design trade-offs and sensitivities to certain design variables, available at the cost of evaluating a simple quadratic polynomial, are presented. In addition, a novel and effective approach to visualizing high dimensional, highly constrained design spaces is enabled through the use of RS models.
NOTE: An updated copy of this ETD was added in July 2012 after there were patron reports of problems with the original file.Ph. D.
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Fantini, Paolo. "Effective multiobjective MDO for conceptual design - An aircraft design perspective." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2219.
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Once the requirements for a new aircraft have been defined, the Conceptual design phase is launched. During this phase one or more designers have the goal of defining and investigating a number of alternative solutions. Through discussion with industry it has become apparent that optimisation tools are seldom used, even though these could greatly enhance the work of the designers.
The objective of the work carried forward has been of identifying, comparing and where necessary improving the most suitable techniques, as well as schemes for their integration, in order to perform effectively Multidisciplinary Design and Optimisation (MDO) in the Conceptual phase of the aircraft design. The techniques that have been investigated include: multi-objective optimisation algorithms, MDO algorithms for treating non-hierarchically decomposable systems and Automatic Differentiation (AD).
As a result an algorithm for performing multiobjective MDO has been developed. Given a complete model for a complex non-hierarchically decomposable system and given a number of objectives and constraints, the algorithm is capable of determining a set of well distributed solutions, representative of both local and global Pareto frontiers.
A number of test cases have been used for evaluating the alternative methodologies and the proposed algorithm. These include a set of complex algebraic test cases typically used for evaluating global optimisation algorithms and a simplified aircraft conceptual design model, which was provided by industry.
The results demonstrate the unique capability of the algorithm of determining well distributed solutions on the global and local Pareto frontiers for global multiobjective continuous nonlinear constrained optimisation problems. The results also show this capability when the algorithm is applied to non-hierarchically decomposable systems, as typically encountered when performing MDO. Further work could extend the approach in order to handle mixed discrete/continuous variables.
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Burgee, Susan L. "A coarse-grained variable-complexity MDO paradigm for HSCT design." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08142009-040544/.
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Stegemann, Patrick. "Untersuchung von Resonanzproblemen am MEYRA E-Rollstuhl 9506 Compact." Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-68411.
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Der Vortrag zeigt die einzelnen notwendigen Schritte auf, die zur Lösung des Resonanzproblems an der Vorderradaufhängung eines E-Rollstuhls der Firma MEYRA-ORTOPEDIA notwendig waren. Alle Lösungsschritte wurden mit Creo Elements/Pro und seinen Modulen Mechanism Design Option (MDO) und Advanced Mechanica erarbeitet.
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Wemming, Hannes. "Validation and integration of a rubber engine model into an MDO environment." Thesis, Linköpings universitet, Fluid och mekanisk systemteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-61028.
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Multidisciplinary design optimization (MDO) is a technique that has found use in the field of aerospace engineering for aircraft design. It uses optimization to simultaneously solve design problems with several disciplines involved. In order to predict aircraft performance an engine performance simulation model, also called “rubber engine”, is vital. The goal of this project is to validate and integrate a rubber engine model into an MDO environment. A method for computer simulation of gas turbine aero engine performance was created. GasTurb v11, a commercial gas turbine performance simulation software, was selected for doing the simulation models. The method was validated by applying it to five different jet engines of different size, different type and different age. It was shown that the simulation engine model results are close to the engine manufacturer data in terms of SFC and net thrust during cruise, maximum climb (MCL) and take off (MTO) thrust ratings. The cruise, take off and climb SFC was in general predicted within 2% error when compared to engine manufacturer performance data. The take off and climb net thrust was in general predicted with less than 5% error. The integration of the rubber engine model with the MDO framework was started and it was demonstrated that the model can run within the MDO software. Four different jet engine models have been prepared for use within the optimization software. The main conclusion is that GasTurb v11 can be used to make accurate jet engine performance simulation models and that it is possible to incorporate these models into an MDO environment.
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Mengmeng, Zhang. "Contributions to Variable Fidelity MDO Framework for Collaborative and Integrated Aircraft Design." Doctoral thesis, KTH, Aerodynamik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168169.
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The thesis develops computational tools for early stages of the aircraft design process. The work focuses on a framework which allows several design teams concurrently to develop a baseline concept into a configuration which meets requirements and whose aerodynamics has been assessed by flight simulation. To this end, a data base format suggested by the German Aerospace Center DLR was adopted in the CEASIOM system, developed in the EU 6th Framework Program, enabling more accurate transonic analysis and tabulation of forces and moments as well as control surface authority assessment. Results from simple, fast models are combined with computationally expensive full CFD results by co-Kriging to speed up productionof the aero-data for flight simulation. Non-linear optimization methods in wing design play an increasingly important role together with computational aerodynamics. High performance computing enables the use of high-fidelity non-linear flow predictions in optimization loops. It is argued that the optimization tools should allow the engineer to influence the process by setting up suitable target pressure distributions for the shape to approach, combined with steps to minimize drag under suitable constraints on geometry, forces, and moments. The simulation framework incorporated into CEASIOM was applied to a number of configurations, conventional as well as un-conventional, such as an a-symmetric twin prop, a canard-configured transonic cruiser, and a novel chinrudder concept for transonic airliners. Aerodynamic shape design by the developed methods was applied to the standard M6 benchmark wing, a joined-wing concept, a wing-tip, and a blended wing-body.Avhandlingen utvecklat beräkningsmoduler för tidiga stadier i flygplanskonstruktionsprocessen. Arbetet kocentreras på ett program-ramverk som låter flera designteam samtidigt utveckla en grund-modell till en konfiguration som uppfyller ställda krav och vars aerodynamik har undersökts med flygsimulering. För att nå detta mål antogs ett data-bas format utarbetat av DLR (German Aerospace Center) i CEASIOM-programpaketet som utvecklats i EUs sjätte ramprogram. Det möjliggjorde noggrannare analys och framtagning av tabeller över krafter och moment liksom bedömning av styrytors funktion i transoniskt fartområde. Resultat från enkla, snabba beräknngsmodeller kombineras via co-Kriging med beräkningsmässigt dyra CFD-körningar för att snabbt ta fram aero-data som behövs för flygsimuleringen. Icke-linjär optimering spelar allt större roll i ving-formgivning, tillsammans med numerisk aerodynamik. Högpresterande datorer medger användning av noggranna icke-linjära strömningsmodeller också i optimerings-slingor. Det argumenteras för att optimerings-verktygen skall ge ingenjörerna direkt inflytande över processen genom definition av fördelaktiga tryckfördelningar som vingformen ska åstadkomma, kombinerat med steg som minimerar luftmotstånd under bivillkor på geometri, krafter och moment. Simulerings-ramverket implementerat i CEASIOM tillämpas så på ett antal konfigurationer, konventionella såväl som o-konventionella: ett osymmetriskt tvåmotorigt propellerplan, och större transoniska flygplan, ett för Mach 0.97 med canardvinge, och ett nytt koncept med hak-roder. Aerodynamisk formgivning med de utvecklade metoderna tillämpas på standardfallet M6-vingen, en transonisk dubbel-vinge, en vingtipp, och en flygande vinge.
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Aevan, Nadjib Danial. "MDO Framework for Design of Human PoweredPropellers using Multi-Objective Genetic Algorithm." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-123626.
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This thesis showcases the challenges, downsides and advantages to building a MultiDisciplinary Optimization (MDO) framework to automate the generation of an efficientpropeller design built for lightly loaded operation, more specifically for humanpowered aircrafts. Two years ago, a human powered aircraft project was initiatedat Linköping University. With the help of several courses, various students performedconceptional design, calculated and finally manufactured a propeller bymeans of various materials and manufacturing techniques. The performance ofthe current propeller is utilized for benchmarking and comparing results obtainedby the MDO process.The developed MDO framework is constructed as a modeFRONITER project wereseveral Computer Aided Engineering softwares (CAE) such as MATLAB, CATIAand XFOIL are connected to perform multiple consequent optimization subprocesses.The user is presented with several design constraints such as blade quantity,required input power, segment-wise airfoil thickness, desired lift coefficientetc. Also, 6 global search optimization algorithms are investigated to determinethe one which generate most efficient result according to several set standards.The optimization process is thereafter initialized by identifying the most efficientchord distribution with a help of an initial blade cross-section which has been previouslyused in other human powered propellers, the findings are thereafter usedto determine the flow conditions at different propeller stations. Two different aerodynamicoptimized shapes are generated with the help of consecutively performedsubprocesses. The optimized propeller requires 7.5 W less input power to generatenearly equivalent thrust as the original propeller with a total efficiency exceedingthe 90 % mark (90.25 %). Moreover, the MDO framework include an automationprocess to generate a CAD design of the optimized propeller. The generatedCAD file illustrates a individual surface blade decrease of 12.5 % compared tothe original design, the lightweight design and lower input power yield an overallpropulsion system which is less tedious to operate.
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Munoz, Guevara Jules Ricardo. "Optimization Strategies for the Synthesis / Design of Hihgly Coupled, Highly Dynamic Energy Systems." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/29251.
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In this work several decomposition strategies for the synthesis / design optimization of highly coupled, highly dynamic energy systems are formally presented and their implementation illustrated. The methods are based on the autonomous optimization of the individual units (components, sub-systems or disciplines), while maintaining energy and cost links between all units, which make up the overall system. All of the approaches are designed to enhance current engineering synthesis / design practices in that: they support the analysis of systems and optimization in a modular way, the results at every step are feasible and constitute an improvement over the initial design state, the groups in charge of the different unit designs are allowed to work concurrently, and permit any level of complexity as to the modeling and optimization of the units.
All of the decomposition methods use the Optimum Response Surface (ORS) of the problem as a basis for analysis. The ORS is a representation of the optimum objective function for various values of the functions that couple the system units1. The complete ORS or an approximation thereof can be used in ways, which lead to different methods. The first decomposition method called the Local Global Optimization (LGO) method requires the creation of the entire ORS by carrying out multiple unit optimizations for various combinations of values of the coupling functions. The creation of the ORS is followed by a system-level optimization in which the best combination of values for the coupling functions is sought
The second decomposition method is called the Iterative Local Global Optimization (ILGO) scheme. In the ILGO method an initial point on the ORS is found, i.e. the unit optimizations are performed for initial arbitrary values of the coupling functions. A linear approximation of the ORS about that initial point is then used to guide the selection of new values for the coupling functions that guarantee an improvement upon the initial design. The process is repeated until no further improvement is achieved. The mathematical properties of the methods depend on the convexity of the ORS, which in turn is affected by the choice of thermodynamic properties used to charecterize the couplings. Examples in the aircraft industry are used to illustrate the application and properties of the methods.Ph. D.
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Schmollgruber, Peter. "Enhancement of the conceptual aircraft design process through certification constraints management and full mission simulations." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0036.
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La conception d'un nouvel avion est initiée durant la phase avant-projet. Dans un premier temps, lesconcepteurs d’aéronefs identifient un ensemble de concepts potentiels pouvant répondre aux exigencesdu client en s’appuyant sur des informations fournies par les spécialistes disciplinaires et expertssystème. Ensuite, les solutions sont évaluées via un processus de dimensionnement basé sur uneanalyse multidisciplinaire. Dans le domaine des avions de transport civil, les objectifs ambitieux entermes de consommation de carburant amènent à étudier des configurations innovantes incluant denouvelles technologies. Cependant, peu de données sur de telles architectures sont disponibles dans lesphases amont de la conception. Ainsi, afin d'éviter une sélection ou élimination erronée d'unesolution, un objectif clé de la recherche en conception d'aéronefs est l’ajout de connaissances dansl'analyse multidisciplinaire.Aujourd’hui, cet objectif est atteint avec différentes approches: application d’optimisationsmultidisciplinaires, ajout de précision grâce aux analyses haute fidélité, introduction de nouvellesdisciplines ou systèmes et enfin, gestion de l'incertitude. Le rôle du concepteur est alors de combinerces options dans un processus de conception multidisciplinaire afin de converger vers le concept leplus performant tout en répondant aux contraintes de certification. Afin d’illustrer ce processus,l’optimisation d'un avion de transport avec assistance au sol pour le décollage qui a mis en évidencel'impact des contraintes de certification sur la conception du véhicule a été effectuée. La revuesuccessive des textes réglementaires et de recherches associées de la gestion du trafic aérien ont concluà la nécessité d’inclure des simulations au sein de l’analyse multidisciplinaire. Tenant compte de cesconclusions, la recherche effectuée dans le cadre de cette thèse propose alors d’ajouter desconnaissances en développant l’analyse et l’optimisation de la conception multidisciplinaire avec unnouveau module de contrainte de certification et des fonctionnalités de simulation complètes.Développé dans le cadre de la thèse, le module de contraintes de certification (CCM) a été utilisé pourrésoudre quatre problèmes d’optimisation associés à un avion de transport civil classique basé surl’outil de dimensionnement ONERA / ISAE-SUPAERO appelé FAST. Grâce à l'interface utilisateurdu CCM, un gain de temps au niveau de la mise en place de ces optimisations a constaté. De plus, lesrésultats ont confirmé la nécessité de définir au mieux et dès que possible les contraintes decertification.Pour atteindre des capacités de simulation complètes, l'analyse multidisciplinaire au sein de FAST aété améliorée. Premièrement, l'outil d'analyse aérodynamique a été modifié afin de générer la base dedonnées complète pour alimenter un modèle à 6 degrés de liberté. Ensuite, un nouveau module decalcul des propriétés d'inertie a été ajouté. Enfin, le simulateur open source JSBSim a été utilisé avecdifférentes lois de contrôle pour augmenter la stabilité et permettre la navigation automatisée. Lacomparaison entre les trajectoires de vol obtenues avec FAST et les données réelles sur les avionsenregistrées avec une antenne ADS-B a confirmé la validité de l'approcheThe design of a new aircraft is initiated at the conceptual design phase. In an initial step, aircraftdesigners, disciplinary and subsystems experts identify a set of potential concepts that could fulfill thecustomer requirements. To select the most promising candidates, aircraft designers carry out the sizingprocess through a Multidisciplinary Design Analysis. Nowadays, in the field of civil transport aircraft,environmental constraints set challenging goals in terms of fuel consumption for the next generationsof airplanes. With the “tube and wing” configuration offering low expectations on furtherimprovements, disruptive vehicle concepts including new technologies are investigated. However,little information on such architectures is available in the early phases of the design process. Thus, inorder to avoid mistakenly selecting or eliminating a wrong concept, a key objective in Aircraft Designresearch is to add knowledge in the Multidisciplinary Design Analysis.Nowadays, this objective is achieved with different approaches: implementation of MultidisciplinaryDesign Optimization, addition of accuracy through high fidelity analyses, introduction of newdisciplines or systems and uncertainty management. The role of the aircraft designer is then tocombine these options in a multidisciplinary design process to converge to the most promising conceptmeeting certification constraints. To illustrate this process, the optimization of a transport aircraftfeaturing ground based assistance has been performed. Using monolithic optimization architecture andadvanced structural models for the wing and fuselage, this study emphasized the impact ofcertification constraints on final results. Further review of the regulatory texts concluded that aircraftsimulation capabilities are needed to assess some requirements. The same need has been identified inthe field of Air Traffic Management that provides constraints for aircraft operations. This researchproposes then to add knowledge through an expansion of the Multidisciplinary Design Analysis andOptimization with a new Certification Constraint Module and full simulation capabilities.Following the development of the Certification Constraint Module (CCM), its capabilities have beenused to perform four optimization problems associated to a conventional civil transport aircraft basedon the ONERA / ISAE-SUPAERO sizing tool called FAST. Facilitated by the Graphical UserInterface of the CCM, the setup time of these optimizations has been reduced and the results clearlyconfirmed the necessity to consider certification constraints very early in the design process in order toselect the most promising concepts.To achieve full simulation capabilities, the multidisciplinary analysis within FAST had to beenhanced. First, the aerodynamics analysis tool has been modified so that necessary coefficients for a6 Degrees-of-Freedom model could be generated. Second, a new module computing inertia propertieshas been added. Last, the open source simulator JSBSim has been used including different controllaws for stability augmentation and automated navigation. The comparison between flight trajectoriesobtained with FAST and real aircraft data recorded with ADS-B antenna confirmed the validity of theapproach
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Dittrich, Robert. "Multidisziplinärer Vorentwurf einer Mach 6 – Hyperschalltransport-Konfiguration mit Hilfe eines Optimierungsverfahrens." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-114799.
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Zukünftige Hyperschalltransportsysteme unterliegen umfangreichen technischen, physikalischen, ökonomischen und ökologischen Anforderungen. Im Detail sind diese Anforderungen stark untereinander verknüpft und somit ist eine multidisziplinäre Behandlung bei einem Entwurf von Hyperschall-Konfigurationen notwendig. Mit Hilfe höherwertiger numerischer Verfahren, wie CFD und FEM, sowie wachsender parallelisierter Rechensysteme lässt sich der Hyperschall-Entwurfsprozess in einen multidisziplinären Optimierungsprozess (MDO-Prozess) überführen. In der vorliegenden Arbeit wird daher ein neu entwickeltes Optimierungswerkzeug für den Vorentwurf von Hyperschall-Flugzeugen vorgestellt, welches die wichtigsten Aspekte der Aerodynamik, der Strukturmechanik, der Flugmechanik, der Antriebsintegration und der Missionsanalyse in einer multidisziplinären Analyse vereint. Alle Teilprozesse werden vollständig automatisiert und in den Analyseprozess integriert. Nach geometrischen Änderungen am Konfigurationsdesign erfolgt eine Aktualisierung des gesamten Entwurfs mit abschließender Leistungsbewertung. Die Funktionalität und Kapazität dieses MDO-Prozesses wird erfolgreich an einem existierenden Hyperschallentwurf, der HYCAT-1A, demonstriertFuture hypersonic transport systems are characterized by extensive and strongly coupled technical, physical, economic and environmental requirements. Hence a multidisciplinary approach for preliminary design studies is necessary. Using high-fidelity numerical tools, e.g. CFD and FEM, on large-scale computer systems the hypersonic design process can be transformed into a multidisciplinary optimization process (MDO process). Thus in the present work a newly developed optimization tool is presented considering aerodynamic, structural, engine and mission characteristics. All sub-processes are integrated in a fully automated analysis environment. During the optimization the outer geometry is changed and all sub-processes are updated accordingly to evaluate the design performance. The functionality and possibilities of the developed MDO process are successfully shown on an existing hypersonic design, the HYCAT-1A configuration
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Raymer, Daniel. "Enhancing Aircraft Conceptual Design using Multidisciplinary Optimization." Doctoral thesis, KTH, Aeronautical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3331.
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Research into the improvement of the Aircraft ConceptualDesign process by the application of MultidisciplinaryOptimization (MDO) is presented. Aircraft conceptual designanalysis codes were incorporated into a variety of optimizationmethods including Orthogonal Steepest Descent (full-factorialstepping search), Monte Carlo, a mutation-based EvolutionaryAlgorithm, and three variants of the Genetic Algorithm withnumerous options. These were compared in the optimization offour notional aircraft concepts, namely an advanced multiroleexport fighter, a commercial airliner, a flying-wing UAV, and ageneral aviation twin of novel asymmetric configuration. Tobetter stress the methods, the commercial airliner design wasdeliberately modified for certain case runs to reflect a verypoor initial choice of design parameters including wingloading, sweep, and aspect ratio.
MDO methods were evaluated in terms of their ability to findthe optimal aircraft, as well as total execution time,convergence history, tendencies to get caught in a localoptimum, sensitivity to the actual problem posed, and overallease of programming and operation. In all, more than a millionparametric variations of these aircraft designs were definedand analyzed in the course of this research.
Following this assessment of the optimization methods, theywere used to study the issue of how the computer optimizationroutine modifies the aircraft geometric inputs to the analysismodules as the design is parametrically changed. Since thiswill ultimately drive the final result obtained, this subjectdeserves serious attention. To investigate this subject,procedures for automated redesign which are suitable foraircraft conceptual design MDO were postulated, programmed, andevaluated as to their impact on optimization results for thesample aircraft and on the realism of the computer-defined"optimum" aircraft. (These are sometimes called vehicle scalinglaws, but should not be confused with aircraft sizing, alsocalled scaling in some circles.)
This study produced several key results with application toboth Aircraft Conceptual Design and MultidisciplinaryOptimization, namely:
MDO techniques truly can improve the weight and cost ofan aircraft design concept in the conceptual design phase.This is accomplished by a relatively small "tweaking" of thekey design variables, and with no additional downstreamcosts.In effect, we get a better airplane for free.
For a smaller number of variables (<6-8), adeterministic searching method (here represented by thefull-factorial Orthogonal Steepest Descent) provides aslightly better final result with about the same number ofcase evaluations
For more variables, evolutionary/genetic methods getclose to the best final result with far-fewer caseevaluations. The eight variables studied herein probablyrepresent the practical upper limit on deterministicsearching methods with todays computer speeds.
Of the evolutionary methods studied herein, the BreederPool approach (which was devised during this research andappears to be new) seems to provide convergence in the fewestnumber ofcase evaluations, and yields results very close tothe deterministic best result. However, all of the methodsstudied produced similar results and any of them is asuitable candidate for use.
Hybrid methods, with a stochastic initial optimizationfollowed by a deterministic final "fine tuning", proved lessdesirable than anticipated.
Not a single case was observed, in over a hundred caseruns totaling over a million parametric design evaluations,of a method returning a local rather than global optimum.Even the modified commercial airliner, with poorly selectedinitial design variables far away from the global solution,was easily "fixed" by all the MDO methods studied.
The postulated set of automated redesign procedures andgeometric constraints provide a more-realistic final result,preventing attainment of an unrealistic "better" finalresult. Especially useful is a new approach defined herein,Net Design Volume, which can prevent unrealisticallyhigh design densities with relatively little setup andcomputational overhead. Further work in this area issuggested, especially in the unexplored area of automatedredesign procedures for discrete variables.
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Lacroix, Jean-Marie. "Étude génétique et physiologique de la régulation osmotique de la biosynthèse du MDO chez Escherichia coli." Paris 11, 1989. http://www.theses.fr/1989PA112147.
Full textAbstract:
Le MDO (Membrane Derived Oligosaccharides) forme une famille d'oligosaccharides localisés dans le périplasme d'Escherichia coli. Son poids moléculaire varie de 1800 à 2300 daltons. Il est constitué d'une chaîne ramifiée de 8 à 10 glucoses liés entre eux par des liaisons β,1→2 et β,1→6 : l'UDP-glucose en est le précurseur. Le MDO est substitué par des résidus phosphoéthanolamines et phosphoglycérols provenant respectivement des phosphatidyléthanolamines et des phosphatidylglycérols, ainsi que par du succinate d'origine inconnue. La biosynthèse du MDO est régulée par l'osmolarité du milieu et la quantité de MDO à très basse osmolarité peut atteindre 5% du poids sec de la bactérie. La quantité de MDO décroît lorsque l'osmolarité du milieu de croissance augmente, pour représenter à haute osmolarité (1 osM) moins d'un dixième de sa valeur maximale. Deux locus intervenant dans la biosynthèse du MDO sont connus. Une mutation spontanée (mdoA1) a permis de localiser le locus mdoA à 23 min. Sur le chromosome d'E. Coli, à 0,2 min. Du marqueur pyrC. Le locus mdoB, non lié à mdoA, a été localisé à 99 min. Un système glucosyl-transférase réalisant in vitro l'élongation β,1→2 d'une chaîne glucosidique a été mis en évidence. Cette activité nécessite la présence d'une fraction membranaire, inactive chez un mutant mdoA, ainsi que de l'Acyl Carrier Protein (ACP), connue jusqu'alors pour intervenir dans la biosynthèse des lipides. Le produit du gène mdoB est la phosphoglycérol-transférase I catalysant la réaction de transfert primaire sur le MDO des résidus phosphoglycérols depuis les phosphatidylglycérols. Une phosphoglycérol-transférase II, dont le gène est inconnu, catalyse le transfert secondaire d'une molécule de MDO à une autre. Le faible nombre de locus connus, dans une chaîne de biosynthèse devant comprendre au moins une dizaine de gènes, s'explique par l'absence de phénotype de croissance lié aux mutations Mdo-. Les données obtenues ont nécessité le dosage systématique du MDO dans les clones.
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Guimarães, Thiago Vinícius Moreira. "Modelo cosmológico unificado com espinores de dimensão de massa um /." Guaratinguetá, 2019. http://hdl.handle.net/11449/181695.
Full textAbstract:
Orientador: Saulo Henrique PereiraResumo: Neste trabalho é construída a evolução completa do Universo impulsionada pelo espinor escuro com dimensão de massa um, chamado MDO. O modelo começa pela inflação cósmica, passando pela era dominada pela matéria escura, terminando com a recente expansão acelerada. Além disso, é feita uma primeira aproximação à teoria de perturbação escalar. Foi mostrado que a dinâmica do campo fermiônico MDO, respeitando um potencial com quebra de simetria, pode reproduzir todas as fases do Universo de uma maneira natural e elegante. As equações dinâmicas em geral e as condições de Slow-Roll, no limite H mp, também são apresentadas para o referido sistema. A análise numérica para o número de e-folds durante a inflação, densidade de energia após este período, o tempo presente e o tamanho real do Universo estão de acordo com o modelo padrão de cosmologia. Uma interpretação da fase inflacionária como resultado do princípio de exclusão de Pauli também é possível se o campo de MDO for tratado como um valor médio de seu análogo quântico
Doutor
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Ryberg, Ann-Britt. "Metamodel-Based Design Optimization : A Multidisciplinary Approach for Automotive Structures." Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-88136.
Full textAbstract:
Automotive companies are exposed to tough competition and therefore strive to design better products in a cheaper and faster manner. This challenge requires continuous improvements of methods and tools, and simulation models are therefore used to evaluate every possible aspect of the product. Optimization has become increasingly popular, but its full potential is not yet utilized. The increased demand for accurate simulation results has led to detailed simulation models that often are computationally expensive to evaluate. Metamodel-based design optimization (MBDO) is an attractive approach to relieve the computational burden during optimization studies. Metamodels are approximations of the detailed simulation models that take little time to evaluate and they are therefore especially attractive when many evaluations are needed, as e.g. in multidisciplinary design optimization (MDO). In this thesis, state-of-the-art methods for metamodel-based design optimization are covered and different multidisciplinary design optimization methods are presented. An efficient MDO process for large-scale automotive structural applications is developed where aspects related to its implementation is considered. The process is described and demonstrated in a simple application example. It is found that the process is efficient, flexible, and suitable for common structural MDO applications within the automotive industry. Furthermore, it fits easily into an existing organization and product development process and improved designs can be obtained even when using metamodels with limited accuracy. It is therefore concluded that by incorporating the described metamodel-based MDO process into the product development, there is a potential for designing better products in a shorter time.
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Driant, Thomas. "Réduction de la traînée aérodynamique et refroidissement d'un tricycle hybride par optimisation paramétrique." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/6990.
Full textAbstract:
La réduction de la traînée aérodynamique des véhicules dans un objectif de diminution de
la consommation énergétique est en plein essor aussi bien pour les véhicules électriques
que thermiques. Cette étude porte sur un tricycle à motorisation hybride dont la forme
et le comportement aérodynamique sont à la frontière entre une motocyclette et une automobile.
L'étude s'inspire des avancées scientifiques sur ces deux types de véhicules en
matière d'aérodynamique. L'objectif principal est de réduire la traînée aérodynamique du
véhicule par des modifications de l'enveloppe externe tout en assurant le refroidissement
du moteur thermique et des composants de la chaîne électrique. On développe une optimisation
topologique de la position des échangeurs sur le tricycle, on conçoit et fabrique
un prototype en fonction des résultats d'optimisation. Ensuite, on valide le prototype par
des essais en soufflerie et on caractérise son aérodynamique ainsi que la sensibilité de la
traînée du véhicule suivant des paramètres comme la vitesse, l'angle de lacet, etc. En n,
l'étude s'oriente vers une approche d'optimisation globale multidisciplinaire permettant
d'atteindre l'objectif principal en fonction des contraintes ayant trait au projet.
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Martz, Matthew. "Preliminary Design of an Autonomous Underwater Vehicle Using a Multiple-Objective Genetic Optimizer." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33291.
Full textAbstract:
The process developed herein uses a Multiple Objective Genetic Optimization (MOGO) algorithm. The optimization is implemented in ModelCenter (MC) from Phoenix Integration. It uses a genetic algorithm that searches the design space for optimal, feasible designs by considering three Measures of Performance (MOPs): Cost, Effectiveness, and Risk. The complete synthesis model is comprised of an input module, the three primary AUV synthesis modules, a constraint module, three objective modules, and a genetic algorithm. The effectiveness rating determined by the synthesis model is based on nine attributes identified in the US Navyâ s UUV Master Plan and four performance-based attributes calculated by the synthesis model. To solve multi-attribute decision problems the Analytical Hierarchy Process (AHP) is used. Once the MOGO has generated a final generation of optimal, feasible designs the decision-maker(s) can choose candidate designs for further analysis. A sample AUV Synthesis was performed and five candidate AUVs were analyzed.Master of Science
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Morris, Craig C. "Flight Dynamic Constraints in Conceptual Aircraft Multidisciplinary Analysis and Design Optimization." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25787.
Full textAbstract:
This work details the development of a stability and control module for implementation into a Multidisciplinary Design Optimization (MDO) framework for the conceptual design of conventional and advanced aircraft. A novel approach, called the Variance Constrained Flying Qualities (VCFQ) approach, is developed to include closed-loop dynamic performance metrics in the design optimization process. The VCFQ approach overcomes the limitations of previous methods in the literature, which only functioned for fully decoupled systems with single inputs to the system. Translation of the modal parameter based flying qualities requirements into state variance upper bounds allows for multiple-input control laws which can guarantee upper bounds on closed-loop performance metrics of the aircraft states and actuators to be rapidly synthesized. A linear matrix inequality (LMI) problem formulation provides a general and scalable numerical technique for computing the feedback control laws using convex optimization tools. The VCFQ approach is exercised in a design optimization study of a relaxed static stability transonic transport aircraft, wherein the empennage assembly is optimized subject to both static constraints and closed-loop dynamic constraints. Under the relaxed static stability assumption, application of the VCFQ approach resulted in a 36% reduction in horizontal tail area and a 32% reduction in vertical tail area as compared to the baseline configuration, which netted a weight savings of approximately 5,200 lbs., a 12% reduction in cruise trimmed drag, and a static margin which was marginally stable or unstable throughout the flight envelope. State variance based dynamic performance constraints offer the ability to analyze large, highly coupled systems, and the linear matrix inequality problem formulation can be extended to include higher-order closed-loop design objectives within the MDO. Recommendations for further development and extensions of this approach are presented at the end.This material is based on research sponsored by Air Force Research Laboratory under agreement number FA8650-09-2-3938. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of Air Force Research Laboratory or the U.S. Government.
Ph. D.
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Riggins, Benjamin Kirby. "Development of a Multi-Disciplinary Design Optimization Framework for a Strut-Braced Wing Transport Aircraft in PACELAB APD 3.1." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52912.
Full textAbstract:
The purpose of this study was to extend the analysis methods in PACELAB APD 3.1, a recent commercially available aircraft preliminary design tool with potential for MDO applications, for higher fidelity with physics-based instead of empirical methods and to enable the analysis of nonconventional aircraft configurations. The implementation of these methods was first validated against both existing models and wind tunnel data. Then, the original and extended PACELAB APD versions were used to perform minimum-fuel optimizations for both a traditional cantilever and strut-braced wing aircraft for a medium-range regional transport mission similar to that of a 737-type aircraft, with a minimum range of 3,115 nm and a cruise Mach number of 0.78. The aerodynamics, engine size / weight estimation and structural modules were heavily modified and extended to accomplish this. Comparisons to results for the same mission generated with FLOPS and VT MDO are also discussed.
For the strut-braced configuration, large fuel savings on the order of 37% over the baseline 737-800 aircraft are predicted, while for the cantilever aircraft savings of 10-30% are predicted depending on whether the default or VT methods are utilized in the PACELAB analysis. This demonstrates the potential of the strut-braced configuration for reducing fuel costs, as well as the benefit of MDO in the aircraft conceptual design process. For the cantilever aircraft, FLOPS and VT MDO predict fuel savings of 8% and 23%, respectively. VT MDO predicts a fuel savings of 28% for the strut-braced aircraft over the baseline.Master of Science
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Friedman, Alex Matthew. "An Approach to Incorporate Additive Manufacturing and Rapid Prototype Testing for Aircraft Conceptual Design to Improve MDO Effectiveness." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/73656.
Full textAbstract:
The primary objectives of this work are two-fold. First, additive manufacturing (AM) and rapid prototype (RP) testing are evaluated for use in production of a wind tunnel (WT) models. Second, an approach was developed to incorporate stability and control (SandC) WT data into aircraft conceptual design multidisciplinary design optimization (MDO). Both objectives are evaluated in terms of data quality, time, and cost.
FDM(TM) and PolyJet AM processes were used for model production at low cost and time. Several models from a representative tailless configuration, ICE 101, were printed and evaluated for strength, cost and time of production. Furthermore, a NACA 0012 model with 20% chord flap was manufactured. Both models were tested in the Virginia Tech (VT) Open-Jet WT for force and moment acquisition. A 1/15th scale ICE 101 model was prepared for manufacturing, but limits of FDM(TM) technology were identified for production.
An approach using WT data was adapted from traditional surrogate-based optimization (SBO), which uses computational fluid dynamics (CFD) for data generation. Split-plot experimental designs were developed for analysis of the WT SBO strategy using historical data and for WT testing of the NACA 0012. Limitations of the VT Open-Jet WT resulted in a process that was not fully effective for a MDO environment. However, resolution of ICE 101 AM challenges and higher quality data from a closed-section WT should result in a fully effective approach to incorporate AM and RP testing in an aircraft conceptual design MDO.Master of Science
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Noya, Pozo Rubén, and Antoine Bouilloux-Lafont. "Development of Acoustic Simulations using Parametric CAD Models in COMSOL." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263872.
Full textAbstract:
With constantly changing regulations on emissions, heavy commercial vehicles manufacturers have to adapt for their products to preserve their quality while meeting these new requirements. Over the past decades, noise emissions have become a great concern and new stricter laws demand companies to decrease their vehicle pass-by noise target values. To address the requirements from different disciplines, Scania follows a simulation driven design process to develop new concept models EATS. The collaboration among engineers from different fields is thereby necessary in order to obtain higher performance silencers. However, the preprocessing step in terms of acoustic simulations is time-consuming, which can slow the concept development process. In this thesis, a new method was introduced to automate the pre-processing of silencer acoustic models and allow for design optimisation based on acoustic performance results. A common Scania product study case was provided to several theses within the NXD organisation. The collaboration among the master thesis workers aimed to demonstrate the benefits of KBE and MDO and how they can be integrated within Scania’s current concept development and product introduction processes. The performed work was divided in the following steps: data collection, method development and concluding work. The first step consisted in gathering sufficient knowledge by conducting a thorough literature review and interviews. Then, an initial method was formulated and tested on a simplified silencer model. Once approved and verified, the method was applied to the study case EATS. The study case showed that a complex product can have its acoustic pre-processing step automated by ensuring a good connectivity among the required software and a correct denomination of the geometrical objects involved in the simulations. The method investigated how morphological optimisations can be performed at both global and local levels to enhance the transmission loss of a silencer. Besides optimising the acoustic performance of the models, the method allowed the identification of correlations and inter-dependencies among their design variables and ouput parameters.Med ständiga förändringar i lagkrav som berör utsläpp måste tillverkare av tunga fordon anpassa sina produkter för att upprätthålla kvalitén samtidigt som de möter de nya kraven. De senaste årtiondena har ljudnivåerna från fordon blivit ett orosmoment, det stiftats striktare lagar som berör den ljudnivå som tunga fordon får emittera under ett förbifartsprov. För att adressera kraven från de olika disciplinerna följer Scania en simuleringsdriven utvecklingsprocess vid utveckling av nya efterbehandlingssystem. Samarbetet mellan ingenjörer från olika fält är därför nödvändigt för att utveckla högre prestanda efterbehandlingsystem. Uppställningen utav de akustiska simuleringarna är tidskrävande, vilket kan leda till en långsam utvecklingsprocess. I detta examensarbete föreslås en ny metod för att introducera en automatiserad uppställning av akustiska simuleringar på efterbehandlingssystem som tillåter optimering av de akustiska egenskaperna. Ett gemensamt studiefall gavs av Scania till flera examensarbeten skrivna vid NXD organisationen. Samarbetet mellan de olika examensarbetena syftade på att demonstrera fördelarna med KBE och MDO och hur de kan bli integrerade i Scanias nuvarande konceptutvecklings- och produktintroduktionsprocess. Examensarbetet är uppdelat i följande steg; datainsamling, metodutveckling och avslutandearbete. Det första steget innefattade insamling av kunskap genom att genomföra en grundlig litteraturstudie och flera intervjuer. Det nästkommande steget innefattade formulering av en initial metod vilken testades på ett simplifierat efterbehandlingssystem. När detta hade verifierats och godkänts applicerades metoden på efterbehandlingssystem i fallstudien. Fallstudien visade att även för en komplex produkt kan uppställningen av de akustiska simuleringarna bli automatiserade genom att säkerställa en bra koppling mellan de olika mjukvarorna och en korrekt benämning av de geometriska objekten involverade i simuleringen. Metoden undersökte hur morfologiska optimeringar kan bli genomförda både på en vittomfattande och lokal nivå för att förbättra transmissionsförlusten i ett efterbehandlingssystem. Förutom att optimera den akustiska prestandan av modellen kunde flera korrelationer mellan de olika konstruktiosparametrar identifieras likväl kunde korrelationer mellan konstruktiosparametrar och systemegenskaperna.
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Lee, Chung Hyun. "Bayesian collaborative sampling: adaptive learning for multidisciplinary design." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42894.
Full textAbstract:
A Bayesian adaptive sampling method is developed for highly coupled multidisciplinary design problems. The method addresses a major challenge in aerospace design: exploration of a design space with computationally expensive analysis tools such as computational fluid dynamics (CFD) or finite element analysis. With a limited analysis budget, it is often impossible to optimize directly or to explore a design space with off-line design of experiments (DoE) and surrogate models. This difficulty is magnified in multidisciplinary problems with feedbacks between disciplines because each design point may require iterative analyses to converge on a compatible solution between different disciplines.
Bayesian Collaborative Sampling (BCS) is a bi-level architecture for adaptive sampling that simulataneously
- concentrates disciplinary analyses in regions of a design space that are favorable to a system-level objective
- guides analyses to regions where interdisciplinary coupling variables are probably compatible
BCS uses Bayesian models and sequential sampling techniques along with elements of the collaborative optimization (CO) architecture for multidisciplinary optimization. The method is tested with the aero-structural design of a glider wing and the aero-propulsion design of a turbojet engine nacelle.
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Júnior, Paulo Roberto Caixeta. "Otimização multidisciplinar em projeto de asas flexíveis." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-22122006-111540/.
Full textAbstract:
A indústria aeronáutica vem promovendo avanços tecnológicos em velocidades crescentes, para sobreviver em mercados extremamente competitivos. Neste cenário, torna-se imprescindível o uso de ferramentas de projeto que agilizem o desenvolvimento de novas aeronaves. Os atuais recursos computacionais permitiram um grande aumento no número de ferramentas que auxiliam o trabalho de projetistas e engenheiros. O projeto de uma aeronave é uma tarefa multidisciplinar por essência, o que logo incentivou o desenvolvimento de ferramentas computacionais que trabalhem com várias áreas ao mesmo tempo. Entre elas se destaca a otimização multidisciplinar em projeto, que une métodos de otimização à modelos matemáticos de áreas distintas de um projeto para encontrar soluções de compromisso. O presente trabalho introduz a otimização multidisciplinar em projeto (Multidisciplinary Design Optimization - MDO) e discorre sobre algumas aplicações possíveis desta metodologia. Foi realizada a implementação de um sistema de MDO para o projeto de asas flexíveis, considerando restrições de aeroelasticidade dinâmica e massa estrutural. Como meta, deseja-se encontrar distribuições ideais de rigidezes flexional e torcional da estrutura da asa, para maximizar a velocidade crítica de flutter e minimizar a massa estrutural. Para tanto, foram utilizados um modelo dinâmico-estrutural baseado no método dos elementos finitos, um modelo aerodinâmico não-estacionário baseado na teoria das faixas e nas soluções bidimensionais de Theodorsen, um modelo de previsão de flutter que utiliza o método K e, por fim, um otimizador baseado no método de algoritmos genéticos (AGs). São apresentados os detalhes empregados em cada modelo, as restrições aplicadas e a maneira como eles interagem ao longo da otimização. É feita uma análise para a escolha dos parâmetros de otimização por AG e em seguida a avaliação de dois casos, para verificação da funcionalidade do sistema implementado. Os resultados obtidos demonstram uma metodologia eficiente, que é capaz de buscar soluções ótimas para problemas propostos, que com devidos ajustes pode ter enorme valor para acelerar o desenvolvimento de novas aeronaves.The aeronautical industry is always trying to speed up technological advances in order to survive in extremely competitive markets. In this scenario, the use of design tools to accelerate the development of new aircraft becomes essential. Current computational resources allow greater increase in the number of design tools to assist the work of aeronautical engineers. In essence, the design of an aircraft is a multidisciplinary task, which stimulates the development of computational tools that work with different areas at the same time. Among them, the multidisciplinary design optimization (MDO) can be distinguished, which combines optimization methods to mathematical models of distinct areas of a design to find compromise solutions. The present work introduces MDO and discourses on some possible applications of this methodology. The implementation of a MDO system for the design of flexible wings, considering dynamic aeroelasticity restrictions and the structural mass, was carried out. As goal, it is desired to find ideal flexional and torsional stiffness distributions of the wing structure, that maximize the critical flutter speed and minimize the structural mass. To do so, it was employed a structural dynamics model based on the finite element method, a nonstationary aerodynamic model based on the strip theory and Theodorsens two-dimensional solutions, a flutter prediction model based on the K method and a genetic algorithm (GA). Details on the model, restrictions applied and the way the models interact to each other through the optimization are presented. It is made an analysis for choosing the GA optimization parameters and then, the evaluation of two cases to verify the functionality of the implemented system. The results obtained illustrate an efficient methodology, capable of searching optimal solutions for proposed problems, that with the right adjustments can be of great value to accelerate the development of new aircraft.
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Kianifar, Mohammed R. "Application of multidisciplinary design optimisation frameworks for engine mapping and calibration." Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/14843.
Full textAbstract:
With ever-increasing numbers of engine actuators to calibrate within increasingly stringent emissions legislation, the engine mapping and calibration task of identifying optimal actuator settings is much more difficult. The aim of this research is to evaluate the feasibility and effectiveness of the Multidisciplinary Design Optimisation (MDO) frameworks to optimise the multi-attribute steady state engine calibration optimisation problems. Accordingly, this research is concentrated on two aspects of the steady state engine calibration optimisation: 1) development of a sequential Design of Experiment (DoE) strategy to enhance the steady state engine mapping process, and 2) application of different MDO architectures to optimally calibrate the complex engine applications. The validation of this research is based on two case studies, the mapping and calibration optimisation of a JLR AJ133 Jaguar GDI engine; and calibration optimisation of an EU6 Jaguar passenger car diesel engine. These case studies illustrated that: -The proposed sequential DoE strategy offers a coherent framework for the engine mapping process including Screening, Model Building, and Model Validation sequences. Applying the DoE strategy for the GDI engine case study, the number of required engine test points was reduced by 30 – 50 %. - The MDO optimisation frameworks offer an effective approach for the steady state engine calibration, delivering a considerable fuel economy benefits. For instance, the MDO/ATC calibration solution reduced the fuel consumption over NEDC drive cycle for the GDI engine case study (i.e. with single injection strategy) by 7.11%, and for the diesel engine case study by 2.5%, compared to the benchmark solutions.
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Damp, Lloyd Hollis. "Multi-Objective and Multidisciplinary Design Optimisation of Unmanned Aerial Vehicle Systems using Hierarchical Asynchronous Parallel Multi-Objective Evolutionary Algorithms." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/1858.
Full textAbstract:
The overall objective of this research was to realise the practical application of Hierarchical Asynchronous Parallel Evolutionary Algorithms for Multi-objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using high fidelity analysis tools. The research looked at the assumed aerodynamics and structures of two production UAV wings and attempted to optimise these wings in isolation to the rest of the vehicle. The project was sponsored by the Asian Office of the Air Force Office of Scientific Research under contract number AOARD-044078. The two vehicles wings which were optimised were based upon assumptions made on the Northrop Grumman Global Hawk (GH), a High Altitude Long Endurance (HALE) vehicle, and the General Atomics Altair (Altair), Medium Altitude Long Endurance (MALE) vehicle. The optimisations for both vehicles were performed at cruise altitude with MTOW minus 5% fuel and a 2.5g load case. The GH was assumed to use NASA LRN 1015 aerofoil at the root, crank and tip locations with five spars and ten ribs. The Altair was assumed to use the NACA4415 aerofoil at all three locations with two internal spars and ten ribs. Both models used a parabolic variation of spar, rib and wing skin thickness as a function of span, and in the case of the wing skin thickness, also chord. The work was carried out by integrating the current University of Sydney designed Evolutionary Optimiser (HAPMOEA) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) tools. The variable values computed by HAPMOEA were subjected to structural and aerodynamic analysis. The aerodynamic analysis computed the pressure loads using a Boeing developed Morino class panel method code named PANAIR. These aerodynamic results were coupled to a FEA code, MSC.Nastran® and the strain and displacement of the wings computed. The fitness of each wing was computed from the outputs of each program. In total, 48 design variables were defined to describe both the structural and aerodynamic properties of the wings subject to several constraints. These variables allowed for the alteration of the three aerofoil sections describing the root, crank and tip sections. They also described the internal structure of the wings allowing for variable flexibility within the wing box structure. These design variables were manipulated by the optimiser such that two fitness functions were minimised. The fitness functions were the overall mass of the simulated wing box structure and the inverse of the lift to drag ratio. Furthermore, six penalty functions were added to further penalise genetically inferior wings and force the optimiser to not pass on their genetic material. The results indicate that given the initial assumptions made on all the aerodynamic and structural properties of the HALE and MALE wings, a reduction in mass and drag is possible through the use of the HAPMOEA code. The code was terminated after 300 evaluations of each hierarchical level due to plateau effects. These evolutionary optimisation results could be further refined through a gradient based optimiser if required. Even though a reduced number of evaluations were performed, weight and drag reductions of between 10 and 20 percent were easy to achieve and indicate that the wings of both vehicles can be optimised.
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Damp, Lloyd Hollis. "Multi-Objective and Multidisciplinary Design Optimisation of Unmanned Aerial Vehicle Systems using Hierarchical Asynchronous Parallel Multi-Objective Evolutionary Algorithms." University of Sydney, 2007. http://hdl.handle.net/2123/1858.
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Master of Engineering (Research)The overall objective of this research was to realise the practical application of Hierarchical Asynchronous Parallel Evolutionary Algorithms for Multi-objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using high fidelity analysis tools. The research looked at the assumed aerodynamics and structures of two production UAV wings and attempted to optimise these wings in isolation to the rest of the vehicle. The project was sponsored by the Asian Office of the Air Force Office of Scientific Research under contract number AOARD-044078. The two vehicles wings which were optimised were based upon assumptions made on the Northrop Grumman Global Hawk (GH), a High Altitude Long Endurance (HALE) vehicle, and the General Atomics Altair (Altair), Medium Altitude Long Endurance (MALE) vehicle. The optimisations for both vehicles were performed at cruise altitude with MTOW minus 5% fuel and a 2.5g load case. The GH was assumed to use NASA LRN 1015 aerofoil at the root, crank and tip locations with five spars and ten ribs. The Altair was assumed to use the NACA4415 aerofoil at all three locations with two internal spars and ten ribs. Both models used a parabolic variation of spar, rib and wing skin thickness as a function of span, and in the case of the wing skin thickness, also chord. The work was carried out by integrating the current University of Sydney designed Evolutionary Optimiser (HAPMOEA) with Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) tools. The variable values computed by HAPMOEA were subjected to structural and aerodynamic analysis. The aerodynamic analysis computed the pressure loads using a Boeing developed Morino class panel method code named PANAIR. These aerodynamic results were coupled to a FEA code, MSC.Nastran® and the strain and displacement of the wings computed. The fitness of each wing was computed from the outputs of each program. In total, 48 design variables were defined to describe both the structural and aerodynamic properties of the wings subject to several constraints. These variables allowed for the alteration of the three aerofoil sections describing the root, crank and tip sections. They also described the internal structure of the wings allowing for variable flexibility within the wing box structure. These design variables were manipulated by the optimiser such that two fitness functions were minimised. The fitness functions were the overall mass of the simulated wing box structure and the inverse of the lift to drag ratio. Furthermore, six penalty functions were added to further penalise genetically inferior wings and force the optimiser to not pass on their genetic material. The results indicate that given the initial assumptions made on all the aerodynamic and structural properties of the HALE and MALE wings, a reduction in mass and drag is possible through the use of the HAPMOEA code. The code was terminated after 300 evaluations of each hierarchical level due to plateau effects. These evolutionary optimisation results could be further refined through a gradient based optimiser if required. Even though a reduced number of evaluations were performed, weight and drag reductions of between 10 and 20 percent were easy to achieve and indicate that the wings of both vehicles can be optimised.
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Thurston, Timothy O'Connor. "Laughter on the Grassland: A Diachronic Study of A mdo Tibetan Comedy and the Public Intellectual in Western China." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430960495.
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Nambiar, Arun N. "Data Exchange in Multi-Disciplinary Design Optimization frameworks." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1088189791.
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Meckstroth, Christopher. "Incorporation of Physics-Based Controllability Analysis in Aircraft Multi-Fidelity MADO Framework." University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1575557306181006.
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Ounis, Houdhayfa. "Conception intégrée par optimisation multicritère multi-niveaux d'un système d'actionnement haute vitesse pour l'avion plus électrique." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/18400/1/OUNIS_Houdhayfa.pdf.
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Les avantages que présentent les systèmes électriques par rapport aux autres systèmes (mécaniques, hydrauliques et pneumatiques) ont permis d’intensifier l’électrification des systèmes embarqués à bord des aéronefs : c’est le concept d’avion plus électrique. Dans ce contexte, l’approche de conception intégrée par optimisation (CIO) de ces systèmes s’avère aujourd’hui une nécessité pour pouvoir répondre aux exigences en termes d’efficacité énergique, de fiabilité et de masse... Dans cette thèse, nous avons appliqué la CIO à une chaine de conversion électromécanique utilisée dans le système de conditionnement d’air d’un avion. Deux objectifs sont ciblés : la minimisation de la masse du système et l’augmentation de son efficacité énergétique. Ces objectifs sont intégrés à diverses contraintes hétérogènes, allant de la qualité réseau au respect de la mission de vol dans le plan couple – vitesse, en passant par la thermique,… Compte tenu de la complexité du système étudié et de son caractère multidisciplinaire, des approches de conception par optimisation dites « MDO » (pour Multidisciplinary Design Optimization) sont étudiées. En effet, au delà des compétences physiques et techniques, la conception intégrée par optimisation des systèmes complexes nécessite des efforts supplémentaires en termes de méthodologies de conception. Nous avons présenté dans cette thèse trois approches : Approches mono-niveau : séquentielle et globale ; Approche multi-niveaux, couplant niveaux système et niveau constituants (filtre, onduleur, machine) ; des formulations adaptées à notre problème de conception sont présentées afin de résoudre les problèmes liés aux optimisations mono-niveau. Les performances des différentes approches de conception sont présentées analysées et comparées. Les résultats obtenus montrent clairement les avantages que présente la formulation multi-niveaux par rapport aux approches classiques de conception.
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Deaton, Joshua D. "Design of Thermal Structures using Topology Optimization." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401302982.
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Bouilloux-Lafont, Antoine, and Pozo Rubén Noya. "Development of Acoustic Simulations using Parametric CAD Models in COMSOL." Thesis, Linköpings universitet, Maskinkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157612.
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With constantly changing regulations on emissions, heavy commercial vehicles manufacturershave to adapt for their products to preserve their quality while meetingthese new requirements. Over the past decades, noise emissions have become a greatconcern and new stricter laws demand companies to decrease their vehicle pass-bynoise target values.To address the requirements from different disciplines, Scania follows a simulationdriven design process to develop new concept models EATS. The collaboration amongengineers from different fields is thereby necessary in order to obtain higher performancesilencers. However, the pre-processing step in terms of acoustic simulationsis time-consuming, which can slow the concept development process.In this thesis, a new method was introduced to automate the pre-processing of silenceracoustic models and allow for design optimisation based on acoustic performanceresults. A common Scania product study case was provided to several theseswithin the NXD organisation. The collaboration among the master thesis workersaimed to demonstrate the benefits of KBE and MDO and how they can be integratedwithin Scania’s current concept development and product introduction processes.The performed work was divided in the following steps: data collection, methoddevelopment and concluding work. The first step consisted in gathering sufficientknowledge by conducting a thorough literature review and interviews. Then, an initialmethod was formulated and tested on a simplified silencer model. Once approvedand verified, the method was applied to the study case EATS.The study case showed that a complex product can have its acoustic pre-processingstep automated by ensuring a good connectivity among the required software anda correct denomination of the geometrical objects involved in the simulations. Themethod investigated how morphological optimisations can be performed at bothglobal and local levels to enhance the transmission loss of a silencer. Besides optimisingthe acoustic performance of the models, the method allowed the identificationof correlations and inter-dependencies among their design variables and ouput parameters.
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Minelli, Andrea. "Optimisation aéro-acoustique de forme d'un aéronef supersonique d'affaire." Thesis, Nice, 2013. http://www.theses.fr/2013NICE4107.
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Ce travail porte sur le développement de méthodes numériques innovantes pour la conception aéro-acoustique optimale de forme des configurations supersoniques. Ce manuscrit présente tout d'abord l'analyse et le développement des approches numériques pour la prévision du bang sonique . Le couplage du calcul CFD tridimensionnel en champ proche prenant en compte la décomposition multipolaire de Fourier et la propagation atmosphérique basée sur un algorithme de tracé de rayons est amélioré par l’intégration d'un processus automatique d' adaptation anisotrope de maillage. La deuxième partie de ce travail se concentre sur l’élaboration et l'application des techniques de conception pour l'optimisation d'une configuration aile-fuselage supersonique. Un module de conception inverse, AIDA , fournit à partir d'une signature acoustique cible au sol à faible bang sonique la géométrie de la configuration correspondante. Pour améliorer a la fois les performances acoustique et aérodynamique, des techniques d'optimisation directes de forme sont utilisées pour résoudre des problèmes d'optimisation mono et multi- disciplinaires et une analyse détaillée est réalisée. Des stratégies innovantes basées sur la coopération et les jeux compétitifs sont enfin appliquées au problème d'optimisation multidisciplinaire offrant une alternative aux algorithmes traditionnels MDO . L’hybridation de ces deux stratégies ouvre la voie a une nouvelle façon d'explorer le front de Pareto de manière efficace. Celle-ci est mise en application sur un cas pratiqueThis work addresses the development of original numerical methods for the aero-acoustic optimal shape design of supersonic configurations. The first axis of the present research is the enhancement of numerical approaches for the prediction of sonic boom. The three dimensional CFD near-field prediction matched using a multipole decomposition approach coupled with atmospheric propagation using on a ray-tracing algorithm is improved by the integration of an automated anisotropic mesh adaptation process. The second part of this work focuses on the formulation and development of design techniques for the optimization of a supersonic wing-body configuration. An inverse design module, AIDA, is able to determine an equivalent configuration provided a target shaped signature at ground level corresponding to a low-boom profile. In order to improve both the aerodynamic and the acoustic performance, direct shape optimization techniques are used to solve single and multi-disciplinary optimization problems and a detailed analysis is carried out. At last, innovative strategies based on cooperation and competitive games are then applied to the multi-disciplinary optimization problem providing an alternative to traditional MDO algorithms. Hybridizing the two strategies opens a new efficient way to explore the Pareto front and this is shown on a practical case
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Costa, Richard Silva. "Função de partição para um campo fermiônico de dimensão de massa um e o halo de matéria escura das galáxias /." Guaratinguetá, 2020. http://hdl.handle.net/11449/192695.
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Orientador: Saulo Henrique PereiraResumo: Efeitos térmicos em teoria de campos são estudados pela chamada Teoria de Campos a Temperatura Finita. Nessa dissertação estudamos os efeitos de temperatura de um campo fermiônico de dimensão de massa um (MDO), que obedece à equação Klein-Gordon em vez da de Dirac. A função de partição foi obtida por meio do formalismo de tempo imaginário e o resultado foi o mesmo que o obtido para campos fermiônicos padrões de Dirac. Obtemos os limites de alta e baixa temperatura, sendo que o limite de baixas temperaturas é proposto como sendo o responsável por manter os halos de matéria escura da galáxia numa região da mesma ordem ou maior que o raio galáctico. Para uma partícula leve com massa de 1eV e densidade de 0.1 partículas por cm³, o valor da massa total da matéria escura devido a partículas MDO é da mesma ordem da massa de uma galáxia típica. Tal resultado pode explicar a matéria escura como sendo formada por partículas fermiônicas de dimensão de massa um. Por fim, comparamos as estimativas de densidade dessas partículas com densidades obtidas através de dados de simulações numéricas e concluímos que para valores de massa entre 0.1eV a 1eV, as partículas MDO produzem uma massa típica de galáxias desde que a densidade delas esteja no intervalo de 10^(-2) cm^(-3) a 10^(5)cm^(-3).
Abstract: Thermal effects in feld theory are studied by the so called Finite Temperature Field Theory. In this dissertation we study the effects of temperature of a mass dimension one (MDO) fermionic field, which obeys the Klein-Gordon equation rather than the Dirac equation. The partition function was obtained via the imaginary time formalism and the result was the same as for the a Dirac fermionic field. We obtained the high and low temperature limits, and the latter is proposed as being responsable for keeping the dark matter halos of galaxies in a region greater than or of the same order as a typical galaxy radius. For a light particle of about 1eV and density of 0.1 particles per cm3 , the value of the total dark mass due to MDO particles is of the same order of a typical galaxy. Such result can explain dark matter as being formed by fermionic particles. Lastly, we compared those particles densities estimates with the ones obtained numeric simulation data and conclude that for mass values between 0.1eV and 1eV, the MDO particles yield a typical galaxy mass as long as their density is in the 10−2 cm−3 to 105 cm−3 interval
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Fife, Nathaniel Luke. "Developing a Design Space Model Using a Multidisciplinary Design Optimization Schema in a Product Lifecycle Management System to Capture Knowledge for Reuse." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd742.pdf.
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BREESE, DAVID RYAN. "MODELING THE EFFECTS OF SOLID STATE ORIENTATION ON BLOWN HIGH MOLECULAR WEIGHT HIGH DENSITY POLYETHYLENE FILMS: A COMPOSITE THEORY APPROACH." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1107958634.
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Balesdent, Mathieu. "Optimisation multidisciplinaire de lanceurs." Phd thesis, Ecole centrale de Nantes, 2011. http://tel.archives-ouvertes.fr/tel-00659362.
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La conception de lanceurs est un problème d'optimisation multidisciplinaire (MDO) complexe qui a la particularité d'intégrer une optimisation de trajectoire très contrainte, difficile à résoudre et fortement couplée à toutes les autres disciplines entrant en jeu dans le processus de conception (e.g. propulsion, aérodynamique, structure, etc.). Cette thèse s'intéresse aux méthodes permettant d'intégrer judicieusement l'optimisation de la trajectoire au sein du processus d'optimisation des variables de conception. Une nouvelle méthode, appelée "Stage-Wise decomposition for Optimal Rocket Design" (SWORD), a été proposée. Celle-ci décompose le processus de conception suivant les différentes phases de vol et transforme le problème d'optimisation de lanceur multiétage en un problème de coordination des optimisations de chacun des étages, plus facile à résoudre. La méthode SWORD a été comparée à la méthode MDO classique (Multi Discipline Feasible) dans le cas d'une optimisation globale d'un lanceur tri-étage. Les résultats montrent que la méthode SWORD permet d'améliorer l'efficacité du processus d'optimisation, tant au niveau de la vitesse de recherche de l'espace de solutions faisables que de la qualité de l'optimum trouvé en temps de calcul limité. Afin d'améliorer la vitesse de convergence de la méthode tout en ne requérant pas de connaissance a priori de l'utilisateur au niveau de l'initialisation et l'espace de recherche, une stratégie d'optimisation dédiée à la méthode SWORD a été développée.
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Domeij, Bäckryd Rebecka. "Multidisciplinary Design Optimization of Automotive Structures." Licentiate thesis, Linköpings universitet, Hållfasthetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-89136.
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Multidisciplinary design optimization (MDO) can be used as an effective tool to improve the design of automotive structures. Large-scale MDO problems typically involve several groups who must work concurrently and autonomously for reasons of efficiency. When performing MDO, a large number of designs need to be rated. Detailed simulation models used to assess automotive design proposals are often computationally expensive to evaluate. A useful MDO process must distribute work to the groups involved and be computationally efficient. In this thesis, MDO methods are assessed in relation to the characteristics of automotive structural applications. Single-level optimization methods have a single optimizer, while multi-level optimization methods have a distributed optimization process. Collaborative optimization and analytical target cascading are possible choices of multi-level optimization methods for automotive structures. They distribute the design process, but are complex. One approach to handle the computationally demanding simulation models involves metamodel-based design optimization (MBDO), where metamodels are used as approximations of the detailed models during optimization studies. Metamodels can be created by individual groups prior to the optimization process, and therefore also offer a way of distributing work. A single-level optimization method in combination with metamodels is concluded to be the most straightforward way of implementing MDO into the development of automotive structures.
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Gobal, Koorosh. "High-Fidelity Multidisciplinary Sensitivity Analysis for Coupled Fluid-Solid Interaction Design." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1483614152174005.
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Lorio, Ryan. "Feasibility of Determining Radioactivity in Lungs Using a Thyroid Uptake Counter." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-08102005-173443/.
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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2006.Ansari, Armin, Committee Member ; Hertel, Nolan, Committee Chair ; Wang, Chris, Committee Member. Includes bibliographical references.
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Stegemann, Patrick. "Kurvenscheibensynthese." Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-68425.
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Der Vortrag behandelt die praktische Umsetzung einer Rast in Rast Kurvenscheibensynthese (Übertragungsfunktion: modifizierte Sinoide) bis zum Ableiten einer ersten Grundform der Kurvenscheibe. Aufgezeigt werden dabei die notwendigen Schritte zur Parametrisierung der Eingabedaten wie Kurvenscheiben- und Übertragungswinkel sowie das spätere Ausleiten einer Spurkurve (Bewegungsaufzeichnung des Kontaktpunktes Kurvenscheibe/Koppel) in das Modell der Kurvenscheibe. Die folgenden notwendigen Optimierungsschritte zur Reduzierung des Krafteingriffswinkels, des Normalkraftverlaufs und der Kurvenscheiben - Mittelpunktslage werden theoretisch behandelt. Das Umsetzen der Optimierung könnte mit Hilfe des Behavioral Modeling Extension - Moduls aus Creo Elements/Pro erfolgen.
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Fenkart, Julia. "“A friend in need is a real friendindeed” : A study about the Sveriges Radio Media Development Office (SR MDO) and the perception of a post-colonial impact." Thesis, Stockholms universitet, Institutionen för mediestudier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-88941.
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Free Media is an essential part of democracy, a goal Sveriges Radio’s Development Program is aiming for. Existing since 1996 based on tax-financing, it offers its long experiences of public broadcasting and its ideal of serving democracy to other countries. The partaking Sveriges Radio journalists provide the countries with assistance for training in management, journalism and technical issues in both broadcasting, print and online media. The present research investigates based on the interviewees’ perceptions to what extent Swedish democracy and Swedish journalistic identity is transmitted during their media (radio) development projects, using post-colonial theory as a guiding theoretical approach. The study is based on interviews with Swedish and foreign journalists who have been involved in radio development projects. The study shows that despite common understandings of democracy and professional aims, differences occur based on the perception of the participants. These cannot be separated from the context and progress outcome of the projects. The study furthermore shows that there exists an ambivalence between the post-colonial awareness among participants.
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Rancruel, Diego Fernando. "A Decomposition Strategy Based on Thermoeconomic Isolation Applied to the Optimal Synthesis/Design and Operation of an Advanced Fighter Aircraft System." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32796.
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A decomposition methodology based on the concept of â thermoeconomic isolationâ applied to the synthesis/design and operational optimization of an advanced tactical fighter aircraft is the focus of this research. Conceptual, time, and physical decomposition were used to solve the system-level as well as unit-level optimization problems. The total system was decomposed into five sub-systems as follows: propulsion sub-system (PS), environmental control sub-system (ECS), fuel loop sub-system (FLS), vapor compressor and PAO loops sub-system (VC/PAOS), and airframe sub-system (AFS) of which the AFS is a non-energy based sub-system.
Configurational optimization was applied. Thus, a number of different configurations for each sub-system were considered. The most promising set of candidate configurations, based on both an energy integration analysis and aerodynamic performance, were developed and detailed thermodynamic, geometric, physical, and aerodynamic models at both design and off-design were formulated and implemented. A decomposition strategy called Iterative Local-Global Optimization (ILGO) developed by Muñoz and von Spakovsky was then applied to the synthesis/design and operational optimization of the advanced tactical fighter aircraft. This decomposition strategy is the first to successfully closely approach the theoretical condition of â thermoeconomic isolationâ when applied to highly complex, highly dynamic non-linear systems. This contrasts with past attempts to approach this condition, all of which were applied to very simple systems under very special and restricted conditions such as those requiring linearity in the models and strictly local decision variables. This is a major advance in decomposition and has now been successfully applied to a number of highly complex and dynamic transportation and stationary systems. This thesis work presents the detailed results from one such application, which additionally considers a non-energy based sub-system (AFS).Master of Science
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Yin, Xuefei. "Application of multidisciplinary design optimisation to engine calibration optimisation." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5630.
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Automotive engines are becoming increasingly technically complex and associated legal emissions standards more restrictive, making the task of identifying optimum actuator settings to use significantly more difficult. Given these challenges, this research aims to develop a process for engine calibration optimisation by exploiting advanced mathematical methods. Validation of this work is based upon a case study describing a steady-state Diesel engine calibration problem. The calibration optimisation problem seeks an optimal combination of actuator settings that minimises fuel consumption, while simultaneously meeting or exceeding the legal emissions constraints over a specified drive cycle. As another engineering target, the engine control maps are required as smooth as possible. The Multidisciplinary Design Optimisation (MDO) Frameworks have been studied to develop the optimisation process for the steady state Diesel engine calibration optimisation problem. Two MDO strategies are proposed for formulating and addressing this optimisation problem, which are All At Once (AAO), Collaborative Optimisation. An innovative MDO formulation has been developed based on the Collaborative Optimisation application for Diesel engine calibration. Form the MDO implementations, the fuel consumption have been significantly improved, while keep the emission at same level compare with the bench mark solution provided by sponsoring company. More importantly, this research has shown the ability of MDO methodologies that manage and organize the Diesel engine calibration optimisation problem more effectively.
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Mosquera, Pedro David Bravo. "Projeto conceitual e análise de desempenho do sistema de admissão de ar em uma aeronave não convencional de combate." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-03082017-131337/.
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A concepção de aeronaves não convencionais a fim de alcançar um determinado desempenho ou melhoria operacional é sem dúvida um dos objetivos mais importantes da engenheira aeronáutica. Tais melhorias envolvem: redução de arrasto, redução da seção transversal, redução de ruído, redução da distância de decolagem e pouso, aumento da eficiência aerodinâmica, aumento da carga útil, entre outros. Por tanto, métodos de otimização multidisciplinar se tornaram em ferramentas muito úteis para aprimorar o projeto conceitual destas aeronaves. Neste contexto, este trabalho teve como objetivo o desenvolvimento do projeto conceitual de uma aeronave não convencional de combate e a análise de desempenho aerodinâmico do seu sistema de admissão de ar (Intake), tendo como principal característica, estar localizado na parte superior da fuselagem da aeronave (Dorsal Intake). O delineamento conceitual foi desenvolvido através da implementação de metodologias de otimização multidisciplinar de projeto (MDO) na fase de projeto paramétrico, integrando conceitos como: entropia estatística, desdobramento da função qualidade (QFD) e análise de restrições. Além disso, foram usados métodos analíticos e teóricos, ferramentas de desenho assistido por computador (CAD) e simulações da dinâmica dos fluidos computacionais (CFD) para otimizar e obter a configuração final da aeronave. Posteriormente, 5 configurações de asa delta foram selecionadas para avaliar as mudanças de desempenho do dorsal intake sob a influência aerodinâmica das superfícies principais da aeronave (Asa e Fuselagem), em regimes de voo subsônico (Mach = 0.4), transônico (Mach = 0.9) e supersônico (Mach = 1.7; 2) a diversos ângulos de ataque (De α = 10º a α = 30º ). Os resultados encontrados neste trabalho foram avaliados em separado, subsequentemente foram integrados, a fim de obter a nova concepção de aeronave não convencional de combate; a aplicação de MDO permitiu estimar as variáveis de projeto ideais para o desenvolvimento do projeto da aeronave, em relação a sua missão. Em contrapartida, os resultados da integração intake-estrutura mostram que apropriadas características de desempenho e compatibilidade foram mantidas durante as fases de voo subsônicas, para as 5 configurações de asa. No entanto, para velocidades transônicas, a configuração canard apresentou um acréscimo nos níveis de recuperação de pressão total, devido ao fluxo de alta energia na parte superior da fuselagem, o qual é produzido pelo vórtice do canard a moderados ângulos de ataque. Finalmente, para velocidades supersônicas, a asa com dispositivos LEX (Leading Edge Extensions) obteve os melhores níveis de recuperação de pressão total, pois a implementação destes dispositivos apresentou uma montagem mais vantajosa com sua fuselagem para gerar o cone de Mach, aumentando os níveis de recuperação de pressão total e reduzindo a distorção na face do motor. No entanto, para velocidades maiores a Mach = 2, sem importar a configuração de asa, a expansão do escoamento sobre a fuselagem e as asas da aeronave produziu um aumento no número Mach local na entrada do intake, o que reduziu os níveis de desempenho e compatibilidade do mesmo. Em consequência, a posição do intake na parte superior da fuselagem representa uma opção de configuração viável para aeronaves que requerem apenas capacidades de ângulo de ataque razoáveis, tais como aeronaves de caça ar-terra, sendo a asa com dispositivos LEX a geometria que representa melhores qualidades de desempenho na maioria dos 3 regimes de voo avaliados.The conception of non-conventional aircraft with the aim of achieving a certain performance or operational improvement is undoubtedly, one of the most important objectives of the aeronautical engineering. These improvements involve: drag reduction, cross section reduction, noise reduction, shortening of take-off and landing distance, increase of aerodynamic efficiency, payload increase, among others. Therefore, optimization multidisciplinary methods became in very important tools to upgrade the conceptual design phase of these aircraft. In this context, this work had as aim the development of the conceptual design of a nonconventional fighter aircraft and the aerodynamic performance analysis of its air intake, having as main characteristic to be located at the top of the fuselage (Dorsal Intake). The conceptual design was developed through the implementation of multidisciplinary design optimization (MDO) methods in the parametric design phase, integrating concepts of: statistical entropy, quality function deployment (QFD) and constraint analysis. Besides that, it was used analytical and theoretical methods, computer-aided design (CAD) tools and computational fluid dynamics (CFD) simulations to optimize and obtain the final aircraft configuration. Subsequently, 5 delta wing configurations were selected to evaluate the dorsal intake performance changes under the aerodynamic influence of the main aircraft surfaces (Wings and Fuselage) in subsonic (Mach = 0.4), transonic (Mach = 0.9) and supersonic (Mach = 1.7; 2) flight regimes, at various angles of attack (From α = 10º to α = 30º ). The results found in this work were evaluated separately, later these were integrated, in order to get the new conception of non-conventional fighter aircraft; the MDO application allowed to estimate the ideal design variables for developing the aircraft design, regarding to its mission. On the other hand, the results of the intake-structure integration shown that appropriate performance and compatibility characteristics were maintained during the subsonic flight stages for the 5 wing configurations. However, for transonic velocities, the canard configuration presented an increase in the total pressure recovery levels, due to the high energy flux on the fuselage, which is produced by the canard vortex at moderate angles of attack. Finally, for supersonic velocities, the wing with LEX (Leading Edge Extensions) devices got the best levels of total pressure recovery, because the implementation of these devices presented a more advantageous assembly with its fuselage to generate the Mach cone, increasing the total pressure recovery levels and reducing the distortion at the engine face. However, for velocities higher than Mach = 2, regardless the wing configuration, the flow expansion on the fuselage and the wings produced an increase in the local Mach number in the intake entrance, which reduced the performance and compatibility levels of it. As a consequence, the top mounted intake position represents an option of viable configuration to aircraft that require only reasonable angles of attack capabilities, such as air-to-ground fighter aircraft, being the wing with LEX devices the geometry that represents better performance qualities in the majority of the 3 evaluated flight regimes.
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Fenkart, Julia. "“A friend in need is a real friend indeed.” : A study about the Sveriges Radio Media Development Office (SR MDO) and the perception of a post-colonial impact." Thesis, Stockholms universitet, Institutionen för mediestudier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89008.
Full textAbstract:
Free Media is an essential part of democracy, a goal Sveriges Radio’s Development Program is aiming for. Existing since 1996 based on tax-financing, it offers its long experiences of public broadcasting and its ideal of serving democracy to other countries. The partaking Sveriges Radio journalists provide the countries with assistance for training in management, journalism and technical issues in both broadcasting, print and online media. The present research investigates based on the interviewees’ perceptions to what extent Swedish democracy and Swedish journalistic identity is transmitted during their media (radio) development projects, using post-colonial theory as a guiding theoretical approach. The study is based on interviews with Swedish and foreign journalists who have been involved in radio development projects. The study shows that despite common understandings of democracy and professional aims, differences occur based on the perception of the participants. These cannot be separated from the context and progress outcome of the projects. The study furthermore shows that there exists an ambivalence between the post- colonial awareness among participants.