Global ETD Search

61	Automated Multidisciplinary Optimizations of Conceptual Rocket Fairings Smart, Ronald S. 13 July 2011 (has links) (PDF) The purpose of this research is to develop and architect a preliminary multidisciplinary design optimization (MDO) tool that creates multiple types of generalized rocket fairing models. These models are sized relative to input geometric models and are analyzed and optimized, taking into account the primary objectives, namely the structural, thermal, and aerodynamic aspects of standard rocket flights. A variety of standard nose cone shapes is used as optimization proof of concept examples, being sized and compared to determine optimal choices based on the input specifications, such as the rocket body geometry and the specified trajectory paths. Any input models can be optimized to their respective best nose cone style or optimized to each of the cone styles individually, depending on the desired constraints. Two proof of concept example rocket model studies are included with varying sizes and speeds. Both have been optimized using the processes described to provide delineative instances into how results are improved and time saved. This is done by optimizing shape and thickness of the fairings while ascertaining if the remaining length downstream on the designated rocket model remains within specified stress and temperature ranges. The first optimized example exhibits a region of high stress downstream on the rocket body model that champions how these tools can be used to catch weaknesses and improve the overall integrity of a rocket design. The second example demonstrates how more established rocket designs can decrease their weight and drag through optimization of the fairing design. Ronald Scott Smart fairing nose cone computer aided design (CAD) optimization finite element analysis (FEA) computation fluid dynamics (CFD) Mechanical Engineering
62	Le mal de dos occupationnel : le rôle de la douleur au dos dans le développement des incapacités au travail Tousignant, Michel 06 1900 (has links) Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal. / Qu'il s'agisse d'économie ou de santé publique, l'étude des incapacités liées au mal de dos occupationnel (MDO) revêt une importance capitale. En effet, les coûts associés au MDO ainsi que le peu de succès observé en matière de prévention font que la recherche en ce domaine demeure une priorité. Ainsi, pour les chercheurs, la pertinence de la présente thèse s'insère dans la nécessité d'améliorer les connaissances sur ce problème de santé publique en pleine croissance que constitue le MDO, afin de mieux comprendre son réseau de causalités et d'augmenter l'efficacité des interventions préventives. Concrètement, dans le cadre d'un objectif général visant à mieux connaître le rôle de la douleur au dos dans le développement des incapacités liées au MDO, nous avons voulu vérifier si la douleur au dos actuelle joue le même rôle dans le développement des incapacités que l'histoire de maux de dos. Nous avons d'abord étudié les interrelations entre la douleur au dos actuelle et l'histoire de maux de dos afin d'améliorer la compréhension de la nature de l'information que ces variables véhiculent. Dans cette optique, nous avons effectué une analyse exploratoire des liens entre les facteurs de risque reconnus comme présentant une évidence suffisante de relation causale avec le MDO en utilisant les données recueillies auprès de travailleurs manuels. L'analyse factorielle nous a permis de dégager deux facteurs : 1) la santé physique et émotionnelle ; 2) la satisfaction au travail. Ce que nous avons appris de nouveau est que l'histoire de maux de dos n'appartient pas à ces deux facteurs alors que la douleur actuelle est incluse dans le construit de santé physique et émotionnelle. Il semble donc que ces deux variables ne véhiculent pas la même information. En deuxième lieu, nous avons abordé le rôle de la douleur au dos actuelle dans le développement des incapacités liées au MDO en étudiant le modèle de Rossignol. Ce modèle spécifie des stades de développement bidirectionnels des incapacités liées au MDO. L'originalité de ce modèle est qu'il suppose que le risque de développer une incapacité complète liée au MDO diffère selon l'état de santé du dos des travailleurs d'une même population. Nous avons dans un premier temps vérifié le risque de développer un MDO au sein d'une population de travailleurs manuels, que nous avons regroupés en quatre catégories selon un gradient de leur état de santé du dos au début de l'étude. Nos résultats ont permis de dégager une tendance : le sous-groupe de travailleurs qui présentent une douleur au dos sans incapacité au travail semble à plus faible risque de MDO que celui des travailleurs ne présentant pas de douleur au dos. Ce résultat inattendu porte à croire que la douleur au dos actuelle joue un double rôle dans le développement des incapacités totales liées au MDO : un rôle préventif des incapacités complètes au travail lorsque la douleur n'engendre pas d'incapacité partielle - vue comme un stimulus favorisant un retour à l'état d'absence de douleur, et un rôle prédictif des incapacités complètes lorsqu'elle est associée à une incapacité partielle au travail. Ce rôle préventif pourrait s'actualiser par l'usage de boucles interactives du travailleur avec son environnement de travail, tel que postulé dans le modèle de Rossignol. Si ce nouveau rôle de la douleur au dos actuelle était démontré par d'autres recherches, nous y verrions un impact direct en santé publique : les travailleurs ne présentant pas de douleur au dos, lesquels ne sont généralement pas les cibles particulières des programmes de prévention, devraient recevoir une attention privilégiée des intervenants en santé et sécurité du travail. Mal de dos occupationnel (MDO) Incapacités Douleur au dos Prévention Santé publique Facteurs de risque Santé physique et émotionnelle Satisfaction au travail Modèle de Rossignol Interventions préventives
63	Quishing i Sikte:Försvarsstrategier och Verktyg : -En Studie om medarbetares Medvetenhet om QR-kod Phishing och En Undersökning av Anti-Phishing-Verktyg Ivarsson, Anton, Stefanescu, Adrian January 2024 (has links) Denna studie undersöker det växande fenomenet quishing (QR-kod phishing) i ljuset av den ökande användningen av QR-koder under COVID-19-pandemin. QR-koder, som är en lösning för beröringsfri interaktion, har blivit allt vanligare och utnyttjas alltmer frekvent i skadliga phishing-attacker mot företag och deras anställda. Under 2023 observerades en dramatisk ökning på över 2 400 procent i en omfattande quishing-kampanj. Undersökningen granskar tidigare studier och forskning om quishing och framhäver behovet av att öka medvetenheten bland anställda och hur man kan implementera effektiva skyddsåtgärder. En central del av studien inkluderar en enkätundersökning och en Attack Simulation Training (AST) som genomförs i samarbete med en Managed Security Service Provider (MSSP). Målet med undersökningen är att belysa anställdas medvetenhet om quishing, deras reaktioner och vad som ligger till grund för de anställdas agerande. Vidare inkluderar studien ett experiment rörande hur effektivt MDO (Microsoft Defender for Office) och andra säkerhetslösningar upptäcker inbäddade QR-koder i olika bildformat och rörliga animationer i epost. Resultaten från enkätundersökningen och ASTn ger insikter som stärker förståelsen för företagens och de anställdas handlande i förhållande till en av många varianter av phishing.Utifrån detta kan rekommendationer för förbättringar, verktyg och policys för att motverka hotet utvecklas och anpassas till hur det verkliga förhållandet är i dagsläget. Studien strävar efter att bidra till en mer omfattande förståelse av quishing och främja framtidens säkerhetskultur inom företagsmiljöer. / This study explores the rising trend of quishing (QR code phishing) in the context of the increased use of QR codes during the COVID-19 pandemic. QR codes, which facilitate contactless interactions, have become more prevalent and are increasingly exploited in malicious phishing attacks targeting companies and their employees. In 2023, a significant surge of over 2,400 percent was observed in a major quishing campaign. The research reviews previous studies on quishing and underscores the necessity of raising employee awareness and implementing effective protective measures. A key component of the study involves a survey and an Attack Simulation Training (AST) conducted in partnership with a Managed Security Service Provider (MSSP). The objective is to assess employees' awareness of quishing, their responses, and the factors influencing their behavior. Additionally, the study includes an experiment to evaluate how effectively Microsoft Defender for Office (MDO) and other security solutions detect embedded QR codes in various image formats and animations in emails. The findings from the survey and AST provide valuable insights into how companies and employees respond to different types of phishing attacks. Based on these insights, recommendations for improvements, tools, and policies can be developed and tailored to the current threat landscape. The study aims to enhance the overall understanding of quishing and promote a stronger security culture within corporate environments. Quishing QR codes Survey Attack Simulation Training Experiment MDO (Microsoft Defender for Office 365) Information security Least privilege Zero trust Quishing QR-koder Enkätundersökning Säkerhetsträning Experiment MDO (Microsoft Defender for Office 365) Informationssäkerhet Least privilege Zero trust Computer and Information Sciences Data- och informationsvetenskap
64	Metamodel-Based Multidisciplinary Design Optimization of Automotive Structures Ryberg, Ann-Britt January 2017 (has links) Multidisciplinary design optimization (MDO) can be used in computer aided engineering (CAE) to efficiently improve and balance performance of automotive structures. However, large-scale MDO is not yet generally integrated within automotive product development due to several challenges, of which excessive computing times is the most important one. In this thesis, a metamodel-based MDO process that fits normal company organizations and CAE-based development processes is presented. The introduction of global metamodels offers means to increase computational efficiency and distribute work without implementing complicated multi-level MDO methods. The presented MDO process is proven to be efficient for thickness optimization studies with the objective to minimize mass. It can also be used for spot weld optimization if the models are prepared correctly. A comparison of different methods reveals that topology optimization, which requires less model preparation and computational effort, is an alternative if load cases involving simulations of linear systems are judged to be of major importance. A technical challenge when performing metamodel-based design optimization is lack of accuracy for metamodels representing complex responses including discontinuities, which are common in for example crashworthiness applications. The decision boundary from a support vector machine (SVM) can be used to identify the border between different types of deformation behaviour. In this thesis, this information is used to improve the accuracy of feedforward neural network metamodels. Three different approaches are tested; to split the design space and fit separate metamodels for the different regions, to add estimated guiding samples to the fitting set along the boundary before a global metamodel is fitted, and to use a special SVM-based sequential sampling method. Substantial improvements in accuracy are observed, and it is found that implementing SVM-based sequential sampling and estimated guiding samples can result in successful optimization studies for cases where more conventional methods fail. metamodel artificial neural network (ANN) support vector machine (SVM) sequential sampling crashworthiness automotive structure spot weld optimization Mechanical Engineering Maskinteknik Applied Mechanics Teknisk mekanik Vehicle Engineering Farkostteknik
65	Multidisciplinary design and optimisation of liquid containers for sloshing and impact Kingsley, Thomas Charles 24 January 2006 (has links) The purpose of this study is to perform an investigation of the numerical methods that may contribute to the design and analysis of liquid containers. The study examines several of these methods individually, namely Computational Fluid Dynamics (CFD) analysis of sloshing and Finite Element Methods (FEM) analysis of impact, to evaluate their contribution to the design cycle. Techniques that enhance the use of the various methods are presented and examined to demonstrate effectiveness. In the case of sloshing analysis, experimental tests performed add to the understanding of the phenomena at hand and qualifies the validity of the numerical method used (CFD). As a final contribution, the study presents a method of utilising impact analysis tools, FEM, and CFD in a Multidisciplinary Design Optimisation (MDO) environment. This is an introductory attempt at demonstrating a single coupled multidisciplinary method of designing liquid containers. The results of the study demonstrate a number of valuable numerical techniques that may be used in the design of liquid containers. The presented Total Deviation Value (TDV) proves to be an effective single quantification of sloshing performance and the CFD tools used to determine the value demonstrate sufficient ability to reproduce the sloshing event itself. More advanced experimental facilities would provide a more in-depth understanding of the limitations of the CFD analysis. The use of numerical optimisation adds a valuable dimension to the use of numerical simulations. Significant design improvements are possible for several design variables without performing exhaustive studies and provide interesting information about design trends. Finally, the use of multiple disciplines, FEM and CFD, in conjunction with the available numerical optimisation routines offers a powerful multidisciplinary design tool that can be adapted to any base geometry and is capable of finding optimal trade offs between the two disciplines according to the designer’s needs. This study provides a platform for further investigations in the use and coupling of sloshing and impact analysis in the design of industrial liquid container applications. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted Fluid structure interaction (FSI) Computational fluid dynamics (CFD) Volume of fluids (VOF) Impact analysis Total deviation value (TDV) Finite element methods (FEM) Multidisciplinary optimisation (MDO) Liquid sloshing Mathematical optimisation UCTD
66	Parametric Optimization Design System for a Fluid Domain Assembly Fisher, Matthew Jackson 22 April 2008 (has links) (PDF) Automated solid modeling, integrated with computational fluid dynamics (CFD) and optimization of a 3D jet turbine engine has never been accomplished. This is due mainly to the computational power required, and the lack of associative parametric modeling tools and techniques necessary to adjust and optimize the design. As an example, the fluid domain of a simple household fan with three blades may contain 500,000 elements per blade passage. Therefore, a complete turbine engine that includes many stages, with sets of thirty or more blades each, will have hundreds of millions of elements. The fluid domains associated with each blade creates a nearly incomprehensible challenge. One method of organizing and passing geometric and non-geometric data is through the utilization of knowledge based engineering (KBE). The focus of this thesis will be the development of a set of techniques utilizing KBE principles to analyze an assembly which includes multiple fluid domains. This comprehensive system will be referred to as the Parametric Optimization Design System (PODS). parametric associative modeling airfoil axial compressor optimization fluid multi-disciplinary optimization MDO analysis jet turbine engine computational fluid dynamics CFD Knowledge-centric CAD-centric DB-centric finite element analysis FEA 3D Mechanical Engineering
67	Parametric CAD Modeling to aid Simulation-Driven Design : An evaluation and improvement of methods used at Scania Grandicki, Andreas, Lokgård, Mattias January 2017 (has links) This report documents a thesis conducted at Scania CV AB in Södertälje, Sweden. The main purpose of the thesis has been to examine and improve upon current practices of parametric CAD-modeling at Scania, with the ultimate goal of increased design automation and simulation-driven design. The thesis was initiated with a literature study, mainly covering the fields of parametric CAD-modeling, design automation and knowledge-based engineering. Furthermore, a questionnaire and multiple interviews were conducted to assess the awareness and mind-set of the employees. Finally, a case-study was carried out to follow current methodologies, and address any deficiencies found. Some of the most important findings were that while parametric modeling has considerable potential in enabling design automation, it is crucial, and most beneficial in terms of automation efficiency, to start with the fundamentals, namely achieving a uniform modeling practice. With these findings, a new proposed methodology has been introduced, as well as a recommended plan for a widespread implementation of parametric modeling at Scania. Such implementation would allow for shorter lead-times, faster adaptation to changing conditions, and reduced development expenditures. CAD CAE parameter parametric simulation MDO DOE simulation-driven design KBE knowledge-based knowledge-based engineering knowledgeware kwa kwe engineering mechanical scania methodology method evaluation model modeling modelling parametrization CATIA vba automation da pdm plm knowledge design intent exploration optimization flexible robust morphological topological Mechanical Engineering Maskinteknik
68	A plm implementation for aerospace systems engineering-conceptual rotorcraft design Hart, Peter Bartholomew 08 April 2009 (has links) The thesis will discuss the Systems Engineering phase of an original Conceptual Design Engineering Methodology for Aerospace Engineering-Vehicle Synthesis. This iterative phase is shown to benefit from digitization of Integrated Product&Process Design (IPPD) activities, through the application of Product Lifecycle Management (PLM) technologies. Requirements analysis through the use of Quality Function Deployment (QFD) and 7 MaP tools is explored as an illustration. A "Requirements Data Manager" (RDM) is used to show the ability to reduce the time and cost to design for both new and legacy/derivative designs. Here the COTS tool Teamcenter Systems Engineering (TCSE) is used as the RDM. The utility of the new methodology is explored through consideration of a legacy RFP based vehicle design proposal and associated aerospace engineering. The 2001 American Helicopter Society (AHS) 18th Student Design Competition RFP is considered as a starting point for the Systems Engineering phase. A Conceptual Design Engineering activity was conducted in 2000/2001 by Graduate students (including the author) in Rotorcraft Engineering at the Daniel Guggenheim School of Aerospace Engineering at the Georgia Institute of Technology, Atlanta GA. This resulted in the "Kingfisher" vehicle design, an advanced search and rescue rotorcraft capable of performing the "Perfect Storm" mission, from the movie of the same name. The associated requirements, architectures, and work breakdown structure data sets for the Kingfisher are used to relate the capabilities of the proposed Integrated Digital Environment (IDE). The IDE is discussed as a repository for legacy knowledge capture, management, and design template creation. A primary thesis theme is to promote the automation of the up-front conceptual definition of complex systems, specifically aerospace vehicles, while anticipating downstream preliminary and full spectrum lifecycle design activities. The thesis forms a basis for additional discussions of PLM tool integration across the engineering, manufacturing, MRO and EOL lifecycle phases to support business management processes. Teamcenter systems engineering Teamcenter community Teamcenter unified Teamcenter engineering Teamcenter manufacturing CATIA V5 Rotorcraft design Boeing AHS Joint heavy lift VPLM MBOM EBOM Product change control Product definition Configuration management Product structure architecture Design engineering Aerospace engineering System engineering PLM CIE IDE SE Affordability Cost savings Executive helicopter Joint chiefs of staff Marine CAE CAD CAM CAA MDO RSM DOE Consulting Engineering management Perfect storm Engineering software Requirements data management CATIA V4 NX Engineering communications RFP Digitization Air Force Navy Army BAMS FIPER ACSYNT Sikorsky Bell Georgia Tech Engineering methodology Requirements engineering System engineering Search Rescue IDE Integrated digital environment Kingfisher Search and rescue Helicopter Helicopter engineering QFD Legacy design IPPD Quality engineering Defense systems acquisition Coast Guard Decision support systems Rotors (Helicopters) Design Concurrent engineering

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