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Seismic performance evaluations and analyses for composite moment frames with smart SMA PR-CFT connectionsHu, Jong Wan 01 April 2008 (has links)
This thesis investigates the performance of composite frame structures with smart
partially-restrained (PR) concrete filled tube (CFT) column connections through
simplified 2D and advanced 3D computational simulations. It also provides a design
methodology for new types of innovative connections based on achieving a beam hinging
mechanism. These types of connections intend to utilize the recentering properties of
super-elastic SMA tension bars, the energy dissipation capacity of low-carbon steel bars,
and the robustness of CFT columns.
In the first part of this study, three different PR-CFT connection prototypes were
designed based on a hierarchy of strength models for each connection component.
Numerical simulations with refined three dimensional (3D) solid elements were
conducted on full scale PR-CFT connection models in order to verify the strength models
and evaluate the system performance under static loading. Based on system information
obtained from these analyses, simplified connection models were formulated by replacing
the individual connection components with spring elements and condensing their
contributions. Connection behavior under cyclic loads was extrapolated and then
compared with the monotonic behavior.
In the second part of this study, the application of these connections to low-rise
composite frames was illustrated by designing both 2D and 3D, 4 and 6 story buildings
for the Los Angeles region. A total of 36 frames were studied. Pushover curves plotted
as the normalized shear force versus inter story drift ratio (ISDR) showed significant
transition points: elastic range or proportional limit, full yielding of the cross-section,
strength hardening, ultimate strength, and strength degradation or stability limit. Based
on the transition points in the monotonic pushover curves, three performance levels were
defined: Design Point, Yield Point, and Ultimate Point. All frames were stable up to the
yield point level. For all fames, after reaching the ultimate point, plastic rotation
increased significantly and concentrated on the lower levels. These observations were
quantified through the use of elastic strength ratios and inelastic curvature ductility ratios.
The composite frames showed superior performance over traditional welded ones in
terms of ductility and stability, and validated the premises of this research.
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Κατάσκευη και έλεγχος ρομποτικού πολυαρθρωτού εργαλείου με χρήση έξυπνων υλικών / Design and control of a redundant robotic tool using smart materialsΕυαγγελίου, Νικόλαος, Γιαταγάνας, Πέτρος 04 October 2011 (has links)
Ο στόχος αυτής της εργασίας είναι να αποκτήσουμε μία βασική γνώση όλων
των διαφορετικών σχεδιαστικών παραμέτρων που πρέπει να εξεταστούν για να
είναι εφικτή η κατασκευή και ο έλεγχος ενός πολυαρθρωτού εργαλείου.
Επιπλέον, όλες οι αναλυτικές μέθοδοι ελέγχου που βασίζονται στις
ιδιαιτερότητες των SMA παρουσιάζονται λεπτομερώς, ώστε να παραχθεί μία
ικανοποιητική λύση βασιζόμενη στις μεταβολές κατάστασης των κραμάτων και
του συγκεκριμένου βραχίονα. Με άλλα λόγια, μία πλήρης γνώση του πώς
σχεδιάζουμε, κατασκευάζουμε, προσομοιώνουμε, ελέγχουμε και απεικονίζουμε
ένα λειτουργικό μικροσκοπικό πολυαρθρωτό βραχίονα, με τένοντες
βασισμένους σε SMA για ελάχιστα επεμβατική χειρουργική είναι ο στόχος της
παρούσας εργασίας. / The purpose of this work is to acquire a fundamental knowledge of all the
different design parameters, which must be evaluated in order to be able to
fabricate and control a multi-DOF manipulator. Moreover, all the analytical
control techniques based on the particularities of the shape memory alloys will
be shown in details, in order to provide an efficient solution based on the
variations of the alloys and the specific manipulator. In other words, the knowhow
of building, evaluating, controlling and displaying a functional tiny multi-
DOF SMA-based manipulator for minimally invasive surgery is the purpose of
this work.
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Un cadre méthodologique et une architecture logicielle orientés agents pour la modélisation et la simulation organisationnelles de chaînes logistiques / A methodological framework and a software architecture oriented agents for modeling and organizational simulation of supply chainsMustapha, Karam 20 October 2011 (has links)
Dans la recherche de performance de chaînes logistiques, la modélisation et la simulation de ces chaînes prenant en compte des aspects organisationnels s‘avèrent nécessaire. Dans cette perspective, nous proposons tout d‘abord un nouveau cadre méthodologique de modélisation et simulation orienté agents de chaînes logistiques, prenant en compte explicitement les aspects organisationnels, tant structurels que dynamiques, ainsi que des observables et indicateurs dans la modélisation de ces chaînes. Ce cadre méthodologique est structuré selon deux niveaux d'abstraction principale qui sont : un niveau conceptuel et un niveau opérationnel. Pour chacun de ces niveaux nous avons différents modèles qui sont proposés et décrit en détail. Ensuite, afin de simuler les modèles de simulation de ces chaines logistiques obtenus par ce cadre méthodologique, nous proposons une architecture logicielle multi-paradigmes spécifique. Cette architecture qui supporte l‘intégration de différentes plates-formes de simulation, est basée sur un médiateur, constituant un système multi-agents, et assurant l‘interaction entre les simulateurs. Les agents de ce médiateur sont chargés de collecter les informations permettant de produire les observables, maintenir la structure organisationnelle lorsque des entités organisationnelles (groupes) sont distribués sur différents simulateurs, l‘interopérabilité entre ces simulateurs, et enfin garantir la validité de la simulation d‘un point de vue temporel. Enfin, la mise en œuvre du cadre méthodologique et de l‘architecture logicielle proposés sont illustrées sur un cas industriel réaliste de chaîne logistique. La présentation des phases de conception est détaillée ainsi que la spécification et l‘implémentation du cas industriel au sein de l‘environnement de modélisation et de simulation proposé. / In the search for performance of supply chains, modeling and simulation of these chains, taking into account the organizational aspects are needed. In this perspective, firstly we propose a new methodology for modeling and simulation of supply chains oriented agents, taking into account explicitly the organizational aspects, both structural and dynamic as well as observable indicators in the modeling of these chains. This methodological framework is structured along two main levels of abstraction, conceptual and operational levels. For each level we have models that are proposed and described in details. Then, to simulate the simulation models of supply chains obtained by this methodological framework, we propose a multi-paradigm software architecture specific. This architecture supports the integration of different platforms simulation is based on a mediator, providing a multi-agent system, and ensuring the interaction between the simulators. The agents of this mediator is responsible for collecting required information to produce observables and maintaining the organizational structure while the organizational entities (groups) are distributed over different simulators and interoperability between these simulators, and finally ensuring the validity of the simulation for a temporal point of view. Finally, the implementation of the methodological framework and the proposed software architecture are shown in a realistic industrial case supply chain. The presentation of the design phase is detailed and the specification and implementation of industrial case in environmental modeling and simulation proposed.
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Uma contribuição ao desenvolvimento de manipuladores antropomorficos com enfase na utilização de musculos artificiais / A contribution to the development of anthropomorphic manipulators with emphasis in the use of artificial musclesMendes, Eduardo Felippe Aguiar 26 February 2007 (has links)
Orientadores: Helder Anibal Hermini, Paulo R. G. Kurka / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-10T05:53:08Z (GMT). No. of bitstreams: 1
Mendes_EduardoFelippeAguiar_M.pdf: 4299696 bytes, checksum: d73355f383b74bd0e49b3bc2473e5b6b (MD5)
Previous issue date: 2007 / Resumo: Este trabalho visou o estudo de manipuladores à semelhança do membro superior humano. Após o estudo do membro superior humano e dos robôs antropomórficos disponíveis tanto na industria quanto no meio acadêmico, utilizaram-se teorias de modelagem geométrica, cinemática direta e cinemática inversa para realizar o modelo de um manipulador robótico antropomórfico. A partir desse modelo desenvolveu-se um software em LabVIEW de Cinemática Direta e Cinemática Inversa de operação em tempo real. Com a intenção de verificar os acionadores mais apropriados disponíveis atualmente, um estudo de músculos artificiais se seguiu, onde se observou a maior viabilidade do músculo artificial de SMA ativado eletricamente. Um protótipo de junta acionada por músculos artificiais foi desenvolvido e controlado via computador. Como resultado deste trabalho conclui-se que há ainda muito para ser desenvolvido na área de manipuladores antropomórficos, principalmente no que diz respeito aos músculos artificiais / Abstract: This work sought the study of manipulators to the similarity of the human superior member. After the study of human superior member, and of anthropomorphics robotics available in the industries and in the academic middle, it was used theories of geometric modelling, direct kinematics modelling and inverse kinematics modelling to make the model of a anthropomorphic robotic manipulator. With that model it grew a software in LabVIEW of real time Direct Kinematics and Inverse Kinematics. With the intention of verifying the available most appropriate actuators, a study of artificial muscles was proceeded, where the largest viability of the artificial muscle of SMA activated electrically was observed. A joint prototype actuated by artificial muscles was developed and controlled through computer. As a result of this work it is ended that there is still a lot to be developed in the area of anthropomorphic manipulators, mainly in what it concerns the artificial muscles / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica
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Improved Release Mechanisms for Aerospace Applications / Förbättrade Releasemekanismer för Flyg- och RymdtillämpningarHamad, Baran, Englund, Markus January 2021 (has links)
Hold down release mechanisms (HDRMs) are used for tightly attaching segments of bodies together when it is desired to release them rapidly at some point. When transporting sensitive payloads on launch vehicles, the challenge arises of releasing the fastened segments of the spacecraft without risking damage to the costly equipment. Non-explosive HDRMs are favourable from a safety perspective as there is a lower risk of producing potentially destructive shock-waves throughout the structure. One variant of a non-explosive HDRM uses a so called 'split spool initiator'. This initiator can only be used once in the actuator mechanism and to reuse the HDRM the initiator must be replaced. The purpose of this thesis is to design an improved split spool initiator which can be reusable while conserving the functionality aspects of the existing design. To achieve this, different ideas were considered and ultimately a solution using shape memory alloys (SMAs) was explored. A prototype was constructed to demonstrate the functionality of the design and simulations are done to determine the forces acting on different parts of the mechanism. / Hold down release-mekanismer (HDRM) används för att säkert kunna fästa samman delar av strukturer för att sedan kunna lossa dessa vid rätt tillfälle. När det transporteras känslig last på exempelvis rymdfarkoster uppkommer utmaningen att göra så på ett sätt som inte riskerar att skada den ofta dyra utrustningen. Det finns en mängd olika HDRM, dessa kan delas upp i två typer som är icke explosiva release-mekanismer och pyrotekniska release-mekanismer. Icke explosiva release-mekanismer har en fördel över pyrotekniska som är att de inte producerar potentiellt destruktiva chock-vågor som sprids genom strukturen. En typ av icke-explosiva release-mekanismer är den så kallade split spool-initieraren. Denna kan endast användas en gång när fästelementet är aktiverat och för att kunna använda fästelementet igen måste hela initieraren bytas ut. Syftet med denna studie har varit att att designa en förbättrad split spool-initierare som är återanvändbar, medan funktionaliteten hos den ursprungliga designen är bevarad. För att åstadkomma detta övervägdes olika idéer och slutligen valdes en lösning som använder minnesmetaller eller Shape memory alloys på engelska (SMA). En prototyp konstruerades för att demonstrera funktionaliteten hos designen. Simuleringar gjordes även för att bestämma krafter som agerade på split spool-strukturen och för att få en överblick över spänningsfördelningen genom initieraren.
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A Study on NiTiSn Low-Temperature Shape Memory Alloys and the Processing of NiTiHf High-Temperature Shape Memory AlloysYoung, Avery W 05 1900 (has links)
Shape memory alloys (SMAs) operating as solid-state actuators pose economic and environmental benefits to the aerospace industry due to their lightweight, compact design, which provides potential for reducing fuel emissions and overall operating cost in aeronautical equipment. Despite wide applicability, the implementation of SMA technology into aerospace-related actuator applications is hindered by harsh environmental conditions, which necessitate extremely high or low transformation temperatures. The versatility of the NiTi-based SMA system shows potential for meeting these demanding material constraints, since transformation temperatures in NiTi can be significantly raised or lowered with ternary alloying elements and/or Ni:Ti ratio adjustments. In this thesis, the expansive transformation capabilities of the NiTi-based SMA system are demonstrated with a low and high-temperature NiTi-based SMA; each encompassing different stages of the SMA development process. First, exploratory work on the NiTiSn SMA system is presented. The viability of NiTiSn alloys as low-temperature SMAs (LTSMAs) was investigated over the course of five alloy heats. The site preference of Sn in near-equiatomic NiTi was examined along with the effects of solution annealing, Ni:Ti ratio adjustments, and precipitation strengthening on the thermomechanical properties of NiTiSn LTSMAs. Second, the thermomechanical processability of NiTiHf high-temperature SMA (HTSMA) wires is presented. The evolution of various microstructural features (grain size reduction, oxide growth, and nano-precipitation) were observed at incremental stages of the hot rolling process and linked to the thermal and mechanical responses of respective HTSMA rods/wires. This work was carried out in an effort to optimize the rolling/drawing process for NiTiHf HTSMAs.
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Contribution à la modélisation et à la vérification des systèmes multi agents / Contribution to Modeling and to Verification of Multi Agent SystemsMarzougui, Borhen 12 June 2014 (has links)
Les Réseaux de Petri (RdP) sont actuellement les approches les plus prometteuses pour modéliser et vérifier les systèmes complexes tels que les Systèmes Multi Agents (SMA). De nombreuses solutions ont été proposées pour remédier aux problèmes de communication, de coordination et d’interaction entre les Agents. Cependant, il n’existe aucune en mesure de traiter, à la fois les aspects structurels et comportementaux, du moins à notre connaissance. La thèse s'intéresse à la problématique de modélisation formelle et de vérification automatique et semi-automatique de propriétés pour les Systèmes Multi Agents. Plus précisément, l'objectif consiste à proposer un nouveau modèle formel original basé sur les réseaux de Petri, les Réseaux de Petri à Agents (RdPA), qui permettent d’exprimer de manière consistante et plus précise les systèmes Multi Agents. Il s’intéresse de plus à l’extension de ce modèle aux fins de modéliser la migration des agents dans le cadre des systèmes à agents mobiles. Cette classe de modèle permet de s’intéresser à la vérification formelle de propriétés classiques comme notamment la vivacité ou l’absence d’interblocage dans le cadre des Systèmes Multi-Agent. / Petri nets (PN) are currently the most promising approaches to model and to verify complex systems such as Multi Agent Systems (MAS). Several solutions have been proposed to solve the problems of communication, coordination and interaction among Agents. However, to best of our knowledge, none of this solution has able to handle both aspects: structural and behavioral. The thesis focuses on the problem of formal modeling and automatic and semi-automatic verification of properties in Multi Agent Systems. More specifically, the objective is to propose a new original formal model based on Petri nets, Agents Petri nets (APN), which express consistently more accurate a Multi Agent Systems. There is growing interest in the extension of this model for modeling the migration of Agents within the mobile Agent systems. This class of model allows focusing on the formal verification of classical properties such as alertness or absence of deadlock in the context of Multi Agent Systems.
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Použití R-materiálu do asfaltových směsí typu asfaltový koberec mastixový / Usage of reclaimed asphalt pavement in stone mastic asphaltCoufalíková, Iva January 2019 (has links)
The dissertation deals with the possibilities of adding recycled asphalt pavement (RAP) to the stone mastic asphalt (SMA), which is increasingly being promoted due to its good resistance to permanent deformations and high traffic load. Thanks to the use of high-quality input materials in production, this is a valuable material source. The theoretical part describes composition of SMA mixture and problems of pavement recycling. The practical part deals with SMA 11S laboratory designs with RAP ratio of 0 to 50%. Based on these suggestions, a trial section with 17 variants was placed, which varied with the content and quality of the RAP and the used additives. All variants have been subjected to functional testing not only on mixtures but also on recovered binders. The results obtained during the dissertation were used to build a certified methodology named "Methodology of application RAP to Stone Mastic Asphalt." In conclusion, the results of the dissertation are summarized.
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Development, Characterization, and Application of Ni<sub>19.5</sub>Ti<sub>50.5</sub>Pd<sub>25</sub>Pt<sub>5</sub> High-Temperature Shape Memory Alloy Helical ActuatorsStebner, Aaron P. January 2007 (has links)
No description available.
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A Comparison of Microarray Analyses: A Mixed Models Approach Versus the Significance Analysis of MicroarraysStephens, Nathan Wallace 20 November 2006 (has links) (PDF)
DNA microarrays are a relatively new technology for assessing the expression levels of thousands of genes simultaneously. Researchers hope to find genes that are differentially expressed by hybridizing cDNA from known treatment sources with various genes spotted on the microarrays. The large number of tests involved in analyzing microarrays has raised new questions in multiple testing. Several approaches for identifying differentially expressed genes have been proposed. This paper considers two: (1) a mixed models approach, and (2) the Signiffcance Analysis of Microarrays.
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