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1
Gasmi, Assia. "Effet de la nanostructuration sur le comportement thermomécanique du Nitinol". Electronic Thesis or Diss., Université de Montpellier (2022-....), 2024. http://www.theses.fr/2024UMONS018.
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La présente thèse s’intéresse à l'alliage à mémoire de forme NiTi, en se concentrant sur l'influence du procédé de nanostructuration superficielle SMAT sur son comportement thermomécanique. À travers quatre chapitres distincts, elle rappelle les principales caractéristiques des alliages à mémoire de forme (AMF), mettant en avant les propriétés exceptionnelles de l'alliage NiTi, et explorant le traitement de nanocristallisation superficielle (SMAT). La caractérisation microstructurale est ensuite approfondie, notamment en étudiant les effets du traitement thermique de recuit et du SMAT sur la transition de phase. Le troisième chapitre se concentre sur les méthodes d'analyse thermomécanique adaptées au NiTi, en examinant les essais de traction et de nanoindentation. Enfin, le quatrième chapitre analyse la caractérisation thermomécanique de l'alliage avant et après le traitement SMAT, mettant en évidence les implications de ces transformations sur son comportement global.La thèse contribue à la compréhension des effets du procédé SMAT sur l'alliage NiTi, révélant des liens entre la microstructure, les phases présentes et les propriétés mécaniques. Les résultats ouvrent des perspectives prometteuses pour la meilleure maîtrise des propriétés de l'alliage NiTi.Les résultats obtenus pour différents traitements SMAT montrent que ce procédé modifie la réponse mécanique du matériau. Elle a aussi une influence sur son état initial, comme l’illustrent les différences dans les courbes de DSC. Les mesures cinématiques (champs de vitesses de déformation) et calorimétriques (champ de source de chaleur) indiquent aussi l’apparition de différences notables dans les réponses en fonction des paramètres de traitement SMAT. L'exploration du comportement lors de cycles de charge/décharge montre une réponse qui se stabiliser après quelques cycles. Les effets de couplage semblent être prépondérants par rapport aux effets dissipatifs. Ces observations devraient être étendues à des chargements en fatigue afin de mieux mettre en évidence les éventuels effets dissipatifs. De même, l’utilisation de modèles d’interprétation plus élaborés permettrait de mieux tenir compte des effets de structure et d’enrichir la compréhension de la relation entre le procédé et les évolutions des propriétésThis thesis focuses on the shape memory alloy NiTi, with a specific emphasis on the influence of the surface nanostructuring process SMAT on its thermomechanical behavior. Through four distinct chapters, it revisits the main characteristics of shape memory alloys (SMAs), highlighting the exceptional properties of the NiTi alloy and exploring the surface nanocrystallization treatment (SMAT). Microstructural characterization is then deeply investigated, particularly by studying the effects of annealing heat treatment and SMAT on phase transition. The third chapter focuses on thermomechanical analysis methods suitable for NiTi, examining tensile tests and nanoindentation. Finally, the fourth chapter analyzes the thermomechanical characterization of the alloy before and after SMAT treatment, highlighting the implications of these transformations on its overall behavior.This thesis contributes to understanding the effects of the SMAT process on the NiTi alloy, revealing links between microstructure, present phases, and mechanical properties. The results offer promising perspectives for better control of the properties of the NiTi alloy.The results obtained for different SMAT treatments show that this process modifies the mechanical response of the material. It also has an influence on its initial state, as illustrated by differences in DSC curves. Kinematic (strain rate fields) and calorimetric (heat source field) measurements also indicate notable differences in responses depending on SMAT processing parameters. Exploration of behavior during load/unload cycles shows a response that stabilizes after a few cycles. Coupling effects seem to be predominant compared to dissipative effects. These observations should be extended to fatigue loading to better highlight any dissipative effects. Similarly, the use of more elaborate interpretation models would allow better consideration of structural effects and enrich the understanding of the relationship between the process and property evolutions
2
Grimslätt, Tove y Sofia Freiholtz. "SMAX : Smart clothing racks". Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-37531.
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Anjum, Sadaf Saad. "Fabrication of smart intercalated polymer-SMA nanocomposite". Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9384.
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Mimicking nature gives rise to many important facets of biomaterials. This study is inspired by nature and reports on the fabrication of an intercalated polymer-NiTi nanocomposite that mimics the structural order of urethral tissue performing micturition. PTFE is chosen due to its hydrophobicity, low surface energy, and thermal and chemical stability. NiTi has been selected as a prime candidate for this research due to its excellent mechanical stability, corrosion resistance, energy absorbance, shape memory and biocompatibility. Nanoscale engineering of intercalated nanocomposites is done by PVD sputtering PTFE and NiTi. FTIR spectroscopy confirms that PTFE reforms as polymer chains after sputtering. Suitable PVD sputtering parameters were selected by investigating their influence on deposition rates, microstructure and properties of PTFE and NiTi thin films. PTFE forms stable nanocomposite coatings with NiTi and displays favourable surface interactions, known as ‘intercalation’. Intercalated PTFE-NiTi films were fabricated as layered and co-sputtered thin films. Co-sputtered nanocomposites contained nearly one-third vacant sites within its internal microstructure because of intercalation while intercalation introduced minute pits in fibrous NiTi columns of layered nanocomposites. These pits allow PTFE to extend their chains and crosslinks, resulting in microstructural and functional changes in the thin films. Intercalated PTFE-NiTi nanocomposites offer a close match to the natural tissue in terms of responding to the fluid contact (wetting angle modifications), and allow the soft and hard matter to incorporate in one framework without any chemical reactions (intercalation). An intercalated microstructure in co-sputtered and layered nanocomposites was verified by EDS-SEM and EDS-TEM techniques. The functional responses were witnessed by changes in water contact angle (WCA) and coefficient of friction (CoF) values measured on the film surface. The WCA (99°) and CoF (0.1 – 0.2) of the intercalated nanocomposite (sample PNT12) were different to the NiTi (top layer). WCA and CoF indicate the internal microstructural interactions because of intercalation. Although the pseudoelastic behaviour of NiTi can provide additional fluid response but the difficulty is an absence of crystallinity in as-deposited NiTi, and the heat treatment that melts PTFE. However, DSC and XRD techniques were employed to find the optimum NiTi composition and transition temperatures for phase transformation related to pseudoelasticity. This study provides the basis to incorporate the shape memory (pseudoelasticity or thermal shape memory effect (shape memory effect)) features of NiTi into the intercalated nanocomposite in future. The intercalated PTFE-NiTi nanocomposite reveals a fascinating research precinct, having the response generating characteristics similar to that of natural tissue.
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Hassan, Mohd Roshdi. "Design, manufacturing and testing of SMA-based smart and cellular structures". Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434620.
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Alazzawi, Sheymaa. "DESIGNING A SMART GREENHOUSE VENTILATION WINDOW BASED ON NITI SMA ACTUATOR". OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1703.
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A multi-functional (sensing -actuating) greenhouse ventilation window heated/cooled naturally by convection was designed to overcome different industry challenges in terms of designing smart applications. This ventilation window design includes a three-pulley system to reduce the load on the NiTi actuator and enhance its long-life time. In addition, using the NiTi actuator allows energy saving due to natural phase transformation induction (i.e. convection) and high force generation compared to the small NiTi wire mass. Structural analysis was used to determine the force generated in the “C-shaped” NiTi wire after loading. Transient thermal and structural analysis also was used to investigate the strain rate effects on the shape memory response of “C shaped” NiTi alloy element under different thermomechanical loadings and boundary conditions. Two types of loading have been applied isothermally or at adiabatic conditions. The results showed a significant effect of the high loading rates on increasing the stress plateau which is caused by the corresponding shift in the transformation temperatures. As a result, it could be expected that the actuator life time could be reduced when a rapid, as opposed to a slow loading rate, is adopted. In addition, the dynamic loading of the NiTi leads to a decrease of the recoverable strain. Experimental work was done to validate the simulation model by testing a commercial NiTi sample dynamically and compare the macroscopic displacement during mechanical loading and the strain recovery process.
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Vouillot, Léna. "Développement des motoneurones chez un modèle amphibien d'amyotrophie spinale généré à l'aide de nucléases". Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0038.
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Les amyotrophies spinales proximales sont des maladies génétiques neuromusculaires caractérisées par la dégénérescence des motoneurones spinaux et une atrophie des muscles squelettiques proximaux. La perte de fonction du gène smn1, un gène essentiel à la survie des motoneurones, entraîne une réduction drastique du niveau de protéine SMN et est, à l’origine des symptômes observés chez les patients. L'amphibien anoure Xenopus tropicalis constitue un très bon petit animal modèle pour étudier cette maladie ainsi que le développement des motoneurones. En effet une diminution de la production de la protéine SMN via l’utilisation de morpholinos a permis de montrer chez les têtards, des défauts de migration des motoneurones ainsi qu’une atrophie des muscles caudaux. Pour développer un modèle héritable de SMA, nous avons utilisé des nucléases tels que les ZFN ou le système CRISPR/Cas pour générer des mutations du gène smn chez Xenopus tropicalis. Nous avons conçu les outils moléculaires pour induire différentes mutations du gène smn avec des ZFN ou le système CRISP/Cas9. Nous avons ensuite validé l'efficacité de ces nucléases dans des embryons in vivo et développé une méthode de recherche de mutations basée sur l’utilisation des endonucléases T7EI et Surveyor. Nous avons obtenu un animal fondateur mutant qui permettra de générer des embryons homozygotes pour la mutation. En parallèle, nous avons développé une lignée transgénique chez Xenopus tropicalis permettant de visualiser les populations de motoneurones spinaux, pour mieux caractériser les animaux mutants smn in vivo. La combinaison de ces deux lignées permettra de mieux comprendre la physiopathologie motoneuronal liée à des mutations de smnSpinal muscular atrophy (SMA) is a neurodegenerative disease characterized by motor neuron loss and skeletal muscle atrophy. In human the loss of function of the smn1 gene, the main supplier of survival motor neuron protein (SMN), leads to reduced levels of SMN and eventually to SMA. The anuran amphibian Xenopus tropicalis is a good animal model for the study of SMA and motor neurons development. Indeed the inhibition of the production of SMN using antisense morpholinos leads to caudal muscular atrophy in tadpoles. To develop an inheritable SMA model, we edited the smn gene in X. tropicalis using zinc-finger nucleases (ZFNs) and CRISPR/Cas system. As a first step, we designed the molecular tools needed to induce mutations of the smn gene using ZFN and CRISPR/cas9. Next we probed the efficiency of these tools and developed a method to identify mutations using T7EI and Surveyor endonucleases. We obtained a mutant frog and thus we will be able to produce homozygous mutant embryos for smn. In parallel we developed a transgenic line of Xenopus tropicalis frogs in which we can image motor neurons populations in vivo. The combination of both lines should enable to increase our knowledge and understanding of motor neuron physiopathology due to smn mutations
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Demény, Maté Agoston. "Analysis of TAF8, a subunit of TFIID and SMAT (smal TAF complex), reveals novel regulation of the assembly of TAF-containing complexes". Université Louis Pasteur (Strasbourg) (1971-2008), 2006. http://www.theses.fr/2006STR13096.
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Alhali, Sara. "Formminneslegeringar : En jämförandestudie mellan en ny typ av förstärkning och traditionella förstärkning av broar". Thesis, Högskolan i Halmstad, Akademin för företagande, innovation och hållbarhet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-45391.
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Den industriella revolutionen kom med behovet av att bygga byggnader och broar, till en början förstod man inte vikten av armering och förstärkning av konstruktion. Men med tiden behövde man komma på någon strategi att göra konstruktionen starkare och mer hållbar, och det var då man började använda sig av förstärkning. I dagens moderna samhälle är det vanligare att bygga med betong, betong är det viktigaste byggmaterialet i världen. Det har flera egenskaper som garanterar en lång livslängd för konstruktionen; dess hållbarhet och styvhet är av störst intresse för att designa betongkonstruktioner. Andra egenskaper såsom täthet och bearbetbarhet är också viktiga. För att utnyttja betongegenskaperna korrekt måste nästan alla strukturer förstärkas på ett eller annat sätt. Därför har man under en lång period gjort stora forskningar på hur man kan göra betong starkt i draghållfasthet och inte bara i tryck. Moderna komplicerade konstruktionsformer kräver nya förstärkningsmetoder, komplexiteten i den nya strukturen både när det gäller höjd och bredd har nödvändiggjort behovet av nya metoder för betongarmering. En metod är användningen av järn-baserade minneslegeringar (Fe-SMA), genom forskning har det visat sig vara en effektiv metod för armering av stål. SMAs har unika egenskaper och det mest speciella är att det återgår till sin ursprungliga form även när det har deformerats. Som ett resultat av detta möjliggör det förstärkning av betong av vilken form och storlek som helst, de goda limegenskaperna hos betong och järn gör installationen komplett. Detta examensarbete resulterade att SMA har väldigt unika egenskaper som kommer att göra stora skillnader i byggbranschen. Detta gäller främst hos broar och är en väldigt aktuell metod som har förmågan att anpassa sig till den omgivande miljön. Utöver det kan den även justera sig själv för att säkerställa optimal och säker drift under normala och svåra belastnings villkor och det minimala kravet för underhåll.
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Hu, Jong Wan. "Seismic performance evaluations and analyses for composite moment frames with smart SMA PR-CFT connections". Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22655.
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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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Henriques, Moreira Daniel. "SimPatrol: um simulador de sistemas multiagentes para o patrulhamento". Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/2248.
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Previous issue date: 2008Conselho Nacional de Desenvolvimento Científico e Tecnológico
Apesar de sistemas multiagentes estarem se tornando cada vez mais comuns no desenvolvimento de software, há ainda que se chegar a um consenso sobre como modelar e comparar diferentes soluções de sistemas multiagentes para um mesmo problema. Em outras palavras, os pesquisadores de tal área ainda estão à procura de benchmarks que sirvam de referência para a comparação de abordagens distintas. Dada a importância do estabelecimento de benchmarks para sistemas multiagentes, uma questão que surge entre os pesquisadores da área de patrulhamento é a possibilidade e o potencial do problema do patrulhamento como um destes benchmarks. Apesar da quantidade de trabalho produzido até este ponto, tem-se encontrado dificuldades para comparar precisamente as soluções propostas para o patrulhamento. Estas dificuldades remetem principalmente à ausência de ferramentas (em especial um simulador unificado) que permitam aos estudiosos se concentrarem na solução do problema em si, e não na sua representação. Partindo deste cenário, este trabalho tem como objetivo discutir o estabelecimento do patrulhamento enquanto um benchmark para sistemas multiagentes. Adicionalmente, como um primeiro passo no sentido de preencher as lacunas que dificultam tal estabelecimento, introduz-se o SimPatrol, um novo simulador voltado para a tarefa de patrulhamento, fortemente inspirado pelos simuladores da RoboCup e TAC. Novos resultados são produzidos a partir de uma avaliação de parte das técnicas propostas pelas pesquisas anteriores frente às novas funcionalidades implementadas pelo simulador, em especial a inédita medida de ociosidade dos vértices, que leva em consideração o tempo de raciocínio gasto pelos patrulheiros
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Paredes, Matta Elizabeth Victoria Adela. "Comportamiento mecánico de las mezclas tipo SMA (STONE MASTIC ASPHALT)". Bachelor's thesis, Universidad Ricardo Palma. Programa Cybertesis PERÚ, 2010. http://cybertesis.urp.edu.pe/urp/2010/paredes_ev/html/index-frames.html.
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Quenum, José Ghislain. "Conception et éxécution d' interactions dans les SMA [Systèmes multi-agents] : spécialisation et sélection de protocoles génériques". Paris 6, 2005. http://www.theses.fr/2005PA066457.
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Jacob, Kiran [Verfasser] y M. [Akademischer Betreuer] Kohl. "Damping of Smart Systems by Shape Memory Alloys (SMAs) / Kiran Jacob ; Betreuer: M. Kohl". Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1231361484/34.
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Yariz, Kemal Oral. "The Chronicles of X-Linked Spinal Muscular Atrophy: The Linkage, The Gene and The SMN Complex". Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/115.
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Spinal Muscular Atrophy (SMA) is an autosomal recessive motor neuron disease. SMA is associated with homozygous mutations in the Survival of Motor Neuron gene I (SMN1). SMN protein does not appear to exist in cells in isolation but associates with several proteins to form a large multi-protein complex. The functions of SMN complex include assembly, metabolism and transport of diverse classes of ribonucleoproteins. X- Linked Spinal Muscular Atrophy is a rare congenital disorder characterized by multiple joint contractures. It is associated with hypotonia, areflexia, chest deformities and congenital joint contractures. A candidate interval was defined for XL-SMA in Xp11.3-Xq11.2 in 1995. The purpose of this study was to refine the XL-SMA gene region and discover the XL-SMA gene. In addition to that, the gene product was investigated to delineate the genotype-phenotype correlation. My studies were focused on single nucleotide polymorphism (SNP) analysis. The candidate gene interval was refined by studying 14 SNPs in the three largest families. This analysis revealed a recombination event which allowed elimination of the NDP gene. Significantly positive LOD scores were obtained from these SNP studies. The exons and exon-intron boundaries of 12 genes were screened. No mutations were found in these genes in affected male samples. In late 2006, UBE1 (Ubiquitin activating enzyme 1) was discovered as the XL-SMA gene. UBE1 protein is responsible for the first step of ubiquitination of proteins in a cell. To investigate a possible common molecular mechanism between SMA and XL-SMA, proteins in the SMN Complex in XL-SMA patient cell lines were studied. SMN and Gemin3 protein levels were found to be consistently lower in XL-SMA patient cell lines (lymphoblasts) compared to healthy cell line. These results imply that there may be a common disease mechanism. To understand if the SMN and Gemin3 RNA levels decrease. RNA expression studies were performed. These studies confirmed that there is no difference of RNA expression of SMN and Gemin3 in XL-SMA cell lines when compared to healthy cell lines. As for UBE1, the same experimental procedure for SMN Complex proteins were repeated with antibodies to UBE1 to determine if there is any decline of UBE1 protein levels in XL-SMA patient cell lines compared to a healthy cell line. There was a decline in protein levels of UBE1 in XL-SMA patients. Two possible models are proposed for a molecular mechanism in XL-SMA: 1) UBE1 involves in degradation of a protein which downregulates SMN Complex (or a protein which stabilizes SMN Complex). When UBE1 is mutated, the protein in question is not degraded and this results in excess downregulation of SMN Complex (maybe via a pathway involving SMN-Gemin3 interaction). 2) UBE1 and UBA6 interact with the proteins of SMN Complex as they monoubiquinate them for different cellular processes. When UBE1 is mutated, UBA6 cannot compensate the deficiency of UBE1, which in turn disrupts normal cellular RNA metabolism required for motor neuron development and survival.
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Miguel-Aliaga, Irene. "Spinal muscular atrophy : of flies, worms and men". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343478.
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Itoh, Fumiko. "Regulation of TGF-β/Smad Signaling Through Smad Interacting Proteins". Doctoral thesis, Uppsala University, Ludwig Institute for Cancer Research, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3690.
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Transforming growth factor-β (TGF-β) superfamily members are multi-functional regulators of cell fate. These factors signal by binding to a limited number of highly conserved transmembrane type I and type II serine/threonine kinase receptors. These receptors initiate signals into the cell via the Smad proteins. Up to date, 8 different mammalian Smads are reported and are divided into three subgroups; receptor regulated Smads (R-Smads), common mediator Smads (Co-Smads) and inhibitory Smads (I-Smads). This thesis investigates the function and regulation of TGF-β/Smad signaling through identification and characterization of Smad interacting proteins.
I-Smads, i.e. Smad6 and Smad7, are potent antagonists of the TGF-β superfamily signaling. We found that Smad7, but not Smad6, inhibits TGF-β1-induced growth inhibition and expression of immediate early response genes. Interestingly, in the absence of ligand, Smad7 was found to be predominantly localized in the nucleus, whereas Smad7 accumulated in the cytoplasm upon TGF-β receptor activation. Moreover, we found that the MH2 domain is important for nuclear export.
To investigate further the role of inhibitory Smads, we have identified AMSH as a Smad6 interacting protein using a yeast two-hybrid screening method. AMSH was previously discovered as the associated molecule with the SH3 domain of STAM. AMSH interacts with I-Smads, but not with R- and Co-Smads upon receptor activation and potentiates BMP-induced activation of transcriptional reporter activity, growth arrest and apoptosis. AMSH was found to prevent Smad6 from binding to activated type I receptors and/or activated R-Smads. Smad anchor for receptor activation (SARA) is critical for Smad2 and Smad3 activation by TGF-β receptors. The present studies show that the localization of SARA in early endosomes is regulated through its FYVE domain. We have found that the FYVE domain of SARA is sufficient and necessary for the early endosomal localization, probably through its interaction with PtdIns(3)P. Moreover, the localization of SARA in early endosomes is required for efficient TGF-β/Smad signaling.
Both Notch and BMP signaling pathways are important for vascular development. We have found that Herp2, which is originally known as one of the Notch target genes, is synergistically induced upon activation of Notch and BMP signaling pathways in endothelial cells (ECs). The critical elements for synergistical activation of Herp2 gene by BMP and Notch pathway were identified. Furthermore, the Notch intracellular domain interacts with Smad5 upon BMP receptor and this interaction becomes stronger in the presence of pCAF. Interestingly, Herp2 was found to antagonize BMP receptor- or Id-mediated EC migration.
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Pachalla, Seshadri Rajagopal. "Analysis of oscillating flow cooled SMA actuator". Texas A&M University, 2004. http://hdl.handle.net/1969.1/2669.
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Shape Memory Alloys (SMA) are a group of metallic alloys that have the ability to return to some previously defined shape or size when subjected to an appropriate thermal cycling procedure. In recent years there has been a lot of research on the development of small, light and, yet, powerful actuators for use in areas like robotics, prosthetics, biomimetics, shape control and grippers. Many of the miniaturized conventional actuators do not have sufficient power output to be useful and SMAs can be used advantageously here.
The widespread use of SMAs in actuators is limited by their low bandwidth. Use of SMAs in two-way actuators requires that they undergo thermal cycling (heating and cooling). While SMAs can be heated quickly by resistive heating, conventional convection cooling mechanisms are much slower as the exothermic austenitic to martensitic phase transformation is accompanied by the release of significant amount of latent heat.
While a number of cooling mechanisms have been studied in SMA actuator literature, most of the cooling mechanisms involve unidirectional forced convection. This may not be the most effective method. Oscillating flow in a channel can sometimes enhance heat transfer over a unidirectional flow. One possible explanation for this heat transfer enhancement is that the oscillatory flow creates a very thin Stokes viscous boundary-layer and hence a large time-dependent transverse temperature gradient at the heated wall. Therefore heat transfer takes place at a large temperature difference, thereby enhancing the heat transfer.
In this work, the heat transfer from an SMA actuator under an oscillating channel is investigated and is compared to steady, unidirectional flow heat transfer.
Oscillating flow is simulated using a finite volume based method. The resulting velocity field is made use of in solving the heat transfer problem using a finite difference scheme. A parametric study is undertaken to identify the optimal flow conditions required to produce the maximum output for a given geometry of the SMA actuator. The latent heat of transformation of the SMA is accounted for by means of a temperature dependent specific heat.
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Dano, Marie-Laure. "SMA-Induced Deformations In general Unsymmetric Laminates". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30390.
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General unsymmetric laminates exhibit large natural curvatures at room temperature. Additionally, inherent to most unsymmetric laminates is the presence of two stable configurations. Multiple configurations and stability issues arise because of the geometric nonlinearities associated with the large curvatures. The laminate can be changed from one stable configuration to the other by a simple snap-through action. This situation offers the opportunity to use shape memory alloys (SMA) attached to the laminate to generate the snap-through forces and change the shape of the laminate on command. Presented is a model which can predict SMA-induced deformations in general unsymmetric laminates and, particularly, the occurrence of the snap through. First, a methodology is developed to predict the deformations of flat general unsymmetric epoxy-matrix composite laminates as they are cooled from their elevated cure temperature. Approximations to the strain fields are used in the expression for the total potential energy, and the Rayleigh-Ritz approach is used to study equilibrium. To further study the laminate deformations, finite-element analyses are performed. Experimental results are presented which confirm the predictions of the developed theory and the finite-element analyses regarding the existence of multiple solutions and the magnitude of the deformations. Results are compared with those of several other investigators. Next, the deformation behavior of general unsymmetric laminates subjected to applied forces is studied. The principle of virtual work is used to derive the equilibrium equations relating the laminate deformations to the applied forces. By solving the equilibrium equations as a function of the force level, relations between the laminate deformations and the applied force are derived, and the force level at which the laminate changes shape is determined. Finally, an existing SMA constitutive model is implemented into the developed theory to predict the deformations of simple structures to SMA-induced forces. Experiments on a narrow aluminium plate with an externally attached SMA actuator are conducted. The experimental results show good agreement with the predictions from the developed theory. Next, the deformation behavior of general unsymmetric laminates subjected to SMA actuators is predicted using the developed theory. Experiments using SMA actuators to generate the snap through of nsymmetric laminates are conducted. Good correlation with the developed theory is obtained.Ph. D.
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Akbulut, Huseyin. "The properties and performance of cellulose fibre reinforced stone mastic asphalt". Thesis, University of Ulster, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342415.
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Chali, Farah. "Innovation physiothérapeutique dans l'amyotrophie spinale infantile : du modèle animal au patient". Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05T075.
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L’amyotrophie spinale infantile (SMA) est une maladie neurodégénérative rare, caractérisée par une perte progressive des motoneurones de la moelle épinière, et pour laquelle aucun traitement curatif n’est disponible. Cette maladie est causée par la mutation du gène SMN1 qui induit une diminution de l’expression de la protéine SMN. Depuis plusieurs des années, notre l’équipe examine les effets de l’exercice sur le développement ou le maintien de l’unité motrice dans des maladies neurodégénératives affectant spécifiquement le motoneurone. Ces études ont notamment permis de mettre en évidence que l’exercice physique pourrait avoir des effets bénéfiques pour l’amyotrophie spinale, dans un modèle de souris SMA de type 2 soumis à un exercice de course sur roue pendant 5 jours (Grondard et al., 2005). Dans notre étude, nous avons comparé les effets de deux programmes d’entraînement différents, d’une durée de 10 mois, basés sur un exercice de course ou sur un exercice de nage, sur des populations de souris SMA de type 3, la forme la moins sévère de la maladie. Dans nos conditions, la course est un exercice de faible intensité et de faible amplitude, mais qui induit plus de lésions musculaires, au contraire de la nage, comme le confirme les mesures de lactate et de créatine kinase circulants. Ces deux paramètres ont des valeurs anormalement hautes chez les souris SMA, suggérant des anomalies métaboliques et de fragilité musculaire, qui sont limitées par les deux programmes d’entraînement. Les analyses du comportement moteur indiquent également que les 10 mois d’entraînement améliorent significativement les capacités motrices des souris SMA, et notamment la résistance à la fatigue avec la nage. Comme attendu, la perte de 46% des motoneurones spinaux enregistrée à 12 mois chez les souris SMA sédentaires est significativement limitée par les deux types d’entrainement, mais avec des efficacités différentes sur les différentes sous‐populations de motoneurones spinaux. En effet, la course protège préférentiellement les motoneurones de faible surface et exprimant ERR‐β, assimilés à des motoneurones lents, et la nage les motoneurones de large surface et exprimant Chodl, assimilés à des motoneurones rapides. De manière surprenante, la neuroprotection induite par l’exercice est indépendante de l’expression de SMN dans la moelle épinière des souris SMA. Une étude de la forme et de la surface des jonctions neuromusculaires dans trois muscles du mollet, le soleus, le plantaris et le tibialis, et une étude du phénotype musculaire de ces mêmes trois muscles confirment le rôle bénéfique de l’entrainement mais aussi les effets différentiels des deux programmes, avec un effet plus important pour la nage. Les améliorations de l’unité motrice, induites par l’exercice, permettent un meilleur fonctionnement neuromusculaire, comme le suggère les mesures électrophysiologiques du muscle plantaire. Pris tous ensemble, ces résultats suggèrent qu’un exercice de nage, à haute intensité, dans des conditions anaérobies, et axé sur le recrutement des muscles extenseurs pourrait être bénéfique pour les patients SMA, notamment pour améliorer les capacités motrices et donc la qualité de vie des patientsObjective: Spinal Muscular Atrophy (SMA) is a group of autosomal recessive neurodegenerative diseases differing in their clinical outcome, characterized by the specific loss of spinal motor‐neurons, caused by insufficient levels of SMN protein expression. No cure is presently available for SMA. While physical exercise might represent a promising approach for alleviating SMA symptoms, the lack of data dealing with the effects of different exercise types on diseased motor‐units still precludes the use of exercise in SMA patients. Methods: We have evaluated the efficiency of two long‐term physical exercise paradigms, either based on high intensity swimming or on low intensity running, in alleviating SMA symptoms in a mild type 3 SMA‐like mouse model. Results: We found that a 10‐month physical training induced significant benefits in terms of resistance to muscle damages, energetic metabolism, muscle fatigue and motor behavior. Both exercise types significantly enhanced motor‐neuron survival, independently of SMN expression, leading to the maintenance of neuromuscular junctions and skeletal muscle phenotypes, particularly in the soleus, plantaris and tibialis of trained mice. Most importantly, both exercises significantly improved neuromuscular excitability properties. Besides, all these training‐induced benefits are quantitatively and qualitatively related to the specific characteristics of each exercise, suggesting that the related neuroprotection is strongly dependent on the specific activation of some motor‐neuron subpopulations. Interpretation: Taken together, the present data show significant long‐term exercise benefits in a mild type 3 SMA context and provide important clues for designing rehabilitation programs in patients
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Pardon, Gaspard. "A feasibility Study of SMA Powder Composite Actuators". Thesis, KTH, Mikrosystemteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91283.
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Aghamaleky, Sarvestany Arwin. "Schwann cell pathology in spinal muscular atrophy (SMA)". Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/15908.
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The childhood neuromuscular disease spinal muscular atrophy (SMA) is caused by low levels of survival motor neuron (SMN) protein. Historically, SMA has been characterised as a disease primarily affecting lower motor neurons. However, recent breakthroughs have revealed defects in other non-neuronal cells and tissues. In vivo analysis of peripheral nerve showed defects in Schwann cells, manifesting as abnormal myelination and delayed maturation of axo-glia interactions. The experiments in this thesis were designed to build on these observations and examine whether Schwann cell defects are intrinsic and occur as a primary result of low levels of SMN in that cell type, or rather represent a secondary consequence of pathology in neighbouring motor neurons. I initially developed a protocol to allow isolation of high-yields of purified, myelination-competent Schwann cells from ‘Taiwanese’ SMA mice. SMA-derived Schwann cells had significantly reduced SMN levels and failed to respond normally to differentiation cues. Increasing SMN levels restored myelin protein expression in Schwann cells from SMA mice. Perturbations in expression of key myelin proteins were likely due to failure of protein translation and/or stability rather than transcriptional defects. Co-cultures of healthy neurons with SMA Schwann cells revealed a significant reduction in myelination compared to cultures where wild-type Schwann cells were used. The presence of SMA Schwann cells also disrupted neurite stability. Perturbations in the expression of key extracellular matrix proteins, such as laminin α2, in SMA-derived Schwann cells suggests that Schwann cells were influencing neurite stability by modulating the composition of the extracellular matrix. Previous studies have demonstrated that low levels of SMN lead to disruption of ubiquitin homeostasis and decreased expression of ubiquitin-like modifier activating enzyme (UBA1) in the neuromuscular system, driving neuromuscular pathology via a beta-catenin dependent pathway. Label-free proteomics analysis of SMA and control Schwann cells identified 195 proteins with modified expression profiles. Bioinformatic analysis of these proteins using Ingenuity Pathway Analysis (IPA) software confirmed that major disruption of protein ubiquitination pathways was also present in Schwann cells from SMA mice. Immunolabeling and proteomics data both revealed that UBA1 levels were significantly reduced in SMA-derived Schwann cells. However, loss of UBA1 in Schwann cells did not lead to downstream modifications in beta-catenin pathways. Pharmacological inhibition of UBA1 in healthy Schwann cells was sufficient to induce defects in myelin protein expression, suggesting that UBA1 defects contribute directly to Schwann cell disruption in SMA. I conclude that low levels of SMN induce intrinsic defects in Schwann cells, mediated at least in part through disruption to ubiquitination pathways.
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Dano, Marie-Laure. "SMA-induced deformations in unsymmetric cross-ply laminates". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09122009-040504/.
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Aphanuphong, Sutha. "Embedded heaters and sensors for micro SMA actuators". Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1458441.
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Acuna, Subia Luis Carlos. "Vlastnosti asfaltových směsí typu SMA s R-materiálem". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371816.
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The aim of the diploma thesis is to verify and compare the properties of bituminous stone mastic asphalt, namely SMA 11S with modified PMB 45 / 80-55 asphalt binder or 50/70 road bitumen binder with rubber granulate. Comparison of properties is performed using functional tests. The thesis is divided into the theoretical and practical part. The theoretical part deals with the familiarization with the use of the SMA mixture, the selected concepts concerning recycling of non-leveled roads are described and described. Attention is paid especially to the recycling of roads in the Czech Republic with an emphasis on hot recycling on the incinerator, which allows increased dosing of Reclaimed Asphalt into asphalt mixtures. In the practical part, the results of the functional tests of the SMA 11S mixture, which have been taken from the test section, are processed and evaluated.
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Gregersen, Petra. "Etikettdesign som förmedlar smak". Thesis, Linköpings universitet, Medie- och Informationsteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139009.
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Följande studie syftar till att undersöka hur en rödvinsflaskas etikett kan designas för att attrahera målgruppen millennials och samtidigt förmedla vinets smak. För att göra detta gjordes en undersökning av målgruppens preferenser genom en kvantitativ inledande studie, följt av en förstudie som undersökte tidigare studier och även designteori. I designprocessen användes den insamlade informationen från den inledande studien och förstudien för att ta designbeslut. Tre etikettalternativ togs fram som sedan validerades med målgruppen i form av en fokusgrupp. Fokusgruppen innefattade delar med kvantitativa enkäter samt smaktest. Resultatet av studien visar att ett av de tre alternativen tenderar att attrahera målgruppen mer och samtidigt förmedla vinets smak mer än de andra. Detta alternativ heter Text över hela och har vit text på en svart bakgrund över hela etiketten. Texten är vinets smaknoter, varumärkesnamn, sort, ursprung samt årtal. All text är lika stor med lika marginaler, dock är vissa ord satt i en högre vikt för att öka läsbarheten. Varumärket är även rött för att det ska bli tydligt vad som är namnet på vinet.
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Segelod, Anton. "Ingen debatt om smak?" Thesis, Umeå universitet, Juridiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-117956.
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Giles, Adam R. "Deflection and shape change of smart composite laminates using shape memory alloy actuators". Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7698.
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Shape memory materials have been known for many years to possess the unique ability of memorising their shape at some temperature. If these materials are pre-strained into the plastic range, they tend to recover their original un-strained shapes via phase transformation when subjected to heat stimulation. In recent years, this shape memory effect (SME) or strain recovery capability has been explored in aerospace structures for actuating the real-time movement of structural components. Among all the shape memory materials, the nickel-titanium based shape memory alloy (SMA) has by far received the most attention because of its high recovery capabilities. Since SMAs are usually drawn into the form of wires, they are particularly suitable for being integrated into fibre-reinforced composite structures. These integrated composite structures with SMA wires are thus called smart adaptive structures. To achieve the SME, these wires are normally embedded in the host composite structures. In returning to their unstrained shape upon heat application, they tend to exert internal stresses on the host composite structures in which they are embedded. This action could result in a controlled change in shape of the structural components. Although there has been a significant amount of research dedicated to characterising and modelling the SME of SMA wires, little experimental work had been done to offer an in-depth understanding of the mechanical behaviour of these smart adaptive polymeric composite structures. This project examined the deflection and shape change of carbon/epoxy and glass/epoxy cantilever beams through heating and cooling of internal nitinol SMA wires/strips. The heat damage mechanism and cyclic behaviour are major factors in the operation of such a system and need to be clearly understood in order to develop and gain confidence for the possible implementation of future smart actuating systems. Therefore, the objectives of the proposed research were to investigate (i) effect of embedding SMA, wires on mechanical properties of host composite, (ii) assessment of single-cycle and multiple-cycle actuation performance of smart beams, and (iii) thermal effects of excessive heat on the surrounding composite matrix.
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Funestig, Tobias y Jonas Wiklund. "Kan SMAT protokollet tillämpas för att mäta den aeroba effekten på vuxna ishockeyspelare? : En experimentell studie med Skating Multistage Aerobic Test (SMAT)". Thesis, Högskolan i Gävle, Idrottsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-24385.
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Introduktion: Vikten av att testa idrottares aeroba effekt idrottsnära har länge varit känd. Skating Multistage Aerobic Test (SMAT) är ett idrottsspecifikt test för ishockeyspelare som utvecklades med unga individer men som idag används på vuxna ishockeyspelare utan att någon validering har skett med den vuxna åldersgruppen. Syfte och frågeställning: En experimentell pilotstudie utfördes med syftet att validera SMAT-protokollet på vuxna ishockeyspelare samt undersöka vilken tillförlitlighet SMAT-protokollet har för att uppskatta testvärdet hos vuxna ishockeyspelare jämfört med det uppmätta värdet. Metod: 6 aktiva ishockeyspelare i division 2 (Ålder: 27,6 ± SD 7,2 år) deltog i studien. Syreupptagningen mättes konstant under utförandet av SMAT med Jaeger Oxycon Mobile system och jämfördes med SMAT protokollets erhållna värden. VO2 platå, blodlaktat, respiratoriska kvot (RER) och % av maxpuls granskades för att undersöka om testet var tillförlitligt. Resultat: På nivå ett var medelvärdet på samtliga 6 deltagares testvärde 24,52 ml syre/min/kg i jämförelse med SMAT protokollets erhållna testvärde på 27,7 ml syre/min/kg. Medeltestvärdet för deltagarna visade en stigande skillnad med SMAT protokollets värden i och med nivåökningarna, på nivå 13 var skillnaden 53,37 (Jaeger systemet) kontra 71,6 ml syre/min/kg (SMAT-protokollet). Samma trend sågs på individuell nivå. 5 av 6 deltagare uppnådde en VO2 platå och ≥95% av maxpuls. Laktatnivåerna innan testet var 0,7 till 1,7 och efter testet 5,6 till 13,6 varav 2 deltagare uppnådde gränsvärdet (≥8 mmol/L-1). 4 av 6 uppnådde RER gränsen på ≥1.10. Diskussion: Skillnaderna i testvärdena mellan SMAT och det uppmätta värdet tros blivit påverkat av ungas arbetsekonomi (skridskoteknik), på grund av sämre arbetsekonomi så kräver unga en högre syreförbrukning för ett givet arbete. Den anaeroba kapaciteten kan också ha påverkat då vuxna har en större förmåga att utnyttja det anaeroba systemet. Slutsats: Resultatet tyder på att SMAT protokollet inte är tillförlitligt för att mäta testvärdet hos vuxna ishockeyspelare.
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Idini, Ilaria. "Polymer stabilised phospholipid nanodiscs". Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629677.
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Membrane proteins are involved in several fundamental biological processes such as transport or signal transduction. Most of them are enzymes, receptors or other important biological macromolecules representing up to 70% of therapeutic targets. Despite the interest in understanding their structures and behaviour the scientific knowledge is still very limited due to several practical difficulties. In 2009 a new platform for membrane protein studies called SMALP (Styrene-Maleic Acid Lipid Particles) nanodiscs was introduced. SMALPs are self-assembled structures formed by a bilayer of phospholipids controlled in diameter by a polystyrene maleic acid (SMA) copolymer belt. The purpose of this research project herein presented was to structurally characterise SMALPs, with analyses aimed to understand the role of both the polymeric and lipid parts in the self-assembly process. A series of investigations were carried out to elucidate the specific copolymer characteristics that allow the assembly into such well-defined, stable and reproducible structures. Experiments performed via small angle X-ray (SAXS) and neutron (SANS) scattering together with nuclear magnetic resonance (NMR), gel-filtration chromatography (GPC), dynamic light scattering (DLS), allowed identification of the specific polymeric characteristics of the copolymer architecture which were revealed to be crucial for the SMALPs assembly process. Investigations performed also addressed the question whether it was possible to assemble nanodiscs with the use of different phospholipids (with different chain length and charged or non-charged heads) and what the impact of the different lipids had on the structures. Finally, further analyses were made to test the physical chemical behaviour of the SMALPs when important environmental parameters such as temperature, pH and salt concentration of the buffer were changed.
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Crothers, Chelsea. "Performer training evolutions: NSP the firstborn son of SMAT". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2414.
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This study examined the Nobbs Suzuki Praxis (NSP), a performer training that evolved as an Australian variant of the Japanese Suzuki Method of Actor Training (SMAT). There has been little research on NSP up until now and this study seeks to establish its importance as a training approach that has the potential to be transformative for the performers who practice it. The study utilised a multi-modal approach that included traditional and practice as research methodologies. The origins of NSP in SMAT were traced to identify similarities and differences, and reveal NSP’s inspirations and the reasons for its subsequent divergent evolution. NSP diverged as the result of an attempt by John Nobbs to clarify misconceptions about SMAT: that it is ‘movement-training’ as opposed to actor-training, that it is an exclusively Japanese theatre form as opposed to a method that could travel and transcend cultural boundaries, and that it is a directorial aesthetic or style of performance rather than a wholistic performer-training. NSP divergences were identified as alterations or additions, depending on their degree of separation from SMAT. This exegesis argues that NSP is more accessible to a broader participant group than SMAT. ‘Broader’ here means the training is more accessible to different ages, levels of experience and physical capacity. The study highlighted the particular intention in NSP of awakening a performer’s personal mythology, a uniquely individual performative state. Workshops and interviews were conducted with beginners to the training to explore the effects of NSP, revealing that it creates more formats for performers to awaken and unleash the potential of their personal mythology. While an experienced and perceptive facilitator is invaluable to a performer’s development, the performer’s access to revelatory experience was evidenced to be independent of what might be characterised as a ‘hierarchical master-student’ relationship. NSP is just one possible permutation of SMAT but this study demonstrates how NSP empowers advanced practitioners to, in turn, develop their own variations on SMAT and NSP as they respond to the individual and specific needs of their context.
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Pinto, Leandro. "Spektakulärt dålig smak : Om representation av smak, status och klass i svensk reality-TV". Thesis, Stockholms universitet, Institutionen för mediestudier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-87010.
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I denna studie undersöks hur smak, status och klass uttrycks i reality-TV-programmen Färjan (Kanal 5) och Danspalatset Playa del Sol (TV3). I program som dessa får vi följa människor som åker på kryssningar, semestrar och shoppar, alltmedan vi förväntas skratta åt dem. De ämnen som dessa program behandlar är tätt förbundna med en förståelse av klass. Syftet med denna uppsats är således att belysa klassaspekter och smakhierarkier. Vidare kommer representationen av smak diskuteras i relation till klass och status. Utifrån denna förståelse av klass som relaterat till smak och status skall sedan klasspositionering i programmen undersökas. Uppsatsens frågeställningar lyder således: Vilka diskurser är framträdande i programmen och hur är de artikulerade? Hur uttrycks markörer för smak, status och klass inom programmen? Hur positioneras och rangordnas smak- och stilmarkörer i programmen? Hur kan dessa tillskrivas samhällsklasser? Den teoretiska ramen domineras av sociologerna Pierre Bourdieu och Beverley Skeggs teorier kring klass. Framförallt Bourdieus teorier kring det sociala rummet och kulturellt kapital appliceras på materialet för att belysa underliggande värderingar och klassaspekter. Det metodologiska tillvägagångssättet är uteslutande baserat på Norman Faircloughs kritiska diskursanalys. Framförallt kommer studien att tillämpa Faircloughs tredimensionella modell för analys av en kommunikativ händelse. Studien visar på hur en semesterdiskurs präglar de båda programmen. Inom semesterdiskursen positioneras val av resmål och fritidsaktiviteter på semestern som något värdeladdat och som kan klassificeras i termer av ”god” och ”dålig” smak. Genom representation av festande som praktik samt av stereotypa kvinnoroller konstruerar programmen en normativ diskurs kring vad som konstituerar smakfullt och smaklöst semestrande. Detta har en tydlig koppling till klass, där klass i programmen formuleras som status. Studien har funnit att programmen bidrar, medvetet eller omedvetet, till att reproducera maktojämlikheter mellan klasserna. Slutsatsen är att klassbegreppet är ständigt närvarande i dessa program, inbäddat i ett klassperspektiv.
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Hariri, Mohammed y not supplied. "Control of Structures Using SMA Wires and Piezoelectric Patches". RMIT University. Aerospace, Mechanical & Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091001.154507.
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Smart materials and structures systems are increasingly being developed to handle more complex problems. One of the main research schemes is the augmentation of the control authority of the smart actuators used in such systems. The augmentation can be obtained by constructing hybrid and multi- smart materials actuator systems and/or by the optimization of the location and orientation of those actuators. In the first part of this study, the alteration of the natural frequency of composite structures using Nitinol-based Shape Memory Alloy (SMA) wires will be presented using the analyses of strain energy perturbations on a plate. These governing strain equations were solved analytically and numerically to show the effect of point forces acting in a distributive manner and the subsequent effect it has on the plate's stiffness and hence it's natural frequency. In the second part of the thesis, a more complex loading condition is considered to investigate piezoceramic actuator control authority in relation to wing flutter control. The advancement in the application of active material induced-strain actuation such as piezoelectric materials in suppression of structural vibrations drew wide interest in its use for wing flutter control. Higher flutter speed and hence wider operating envelope was achieved by delaying the coalescence of the eigenvalues for plunge and twist modes. . This delay is obtained by adding more strain energy to the system as a result of the activation of the piezoelectric actuators. Most of the studies done were by controlling the plunge/bending motion, where the piezoelectric actuators are bonded longitudinally to produce bending moments. In this study, the control of the pitch/twisting motion was investigated and it showed better control of flutter by using simultaneous multi-actuations compared to single piezo actuations. It was shown that within the scope of the angular orientations of the piezoelectric patches investigated in this study, piezoelectric patches oriented about +150 from the beam's longitudinal ax is resulted in the most optimal piezo-configuration. This was corroborated by both the numerical flutter speed and actuator moment evaluations. In addition, the orientation of the piezoelectric patches was shown to significantly affect the pitch angle of the beam relative to each other. The damping ratio was also investigated and this showed greater instability for piezoelectric patches oriented at negative angles, thus further supporting the finding of the aforementioned optimal orientation of +150. These findings confirmed the dominance of the base (closest to the fixed portion of the beam) piezo when actuated with other piezos.
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Sitnikova, Elena. "Dynamic behaviour of an impact system with SMA restraint". Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202764.
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The interest in use of SMAs in vibrational systems is stimulated by their ability to dissipate energy and consequently their potential to control the dynamic behaviour of the system. In this thesis nonlinear dynamics of an impact oscillator with one sided motion constraint made of a shape memory alloy (SMA) is investigated. The pseudoelastic behaviour of SMAs is characterized by high non-linear recovery deformations and energy dissipation due to the occurrence of hysteresis. The thermo-mechanical description of the SMA element follows the formulation proposed by Bernardini et al. [1,2]. Extensive numerical investigations into the influence of the forcing parameters, which characterize the intensity of the load acting on the SMA has been carried out. They suggest that the system can exhibit complex dynamic responses, which if appropriately controlled can be used for vibration reduction. The comparison with the equivalent elastic oscillator response has shown that the use of the SMA can significantly change the dynamic response of the system. Whereas low amplitude regimes are not affected by the SMA element, at resonances when the response amplitudes are large, a significant vibration reduction is achieved due to the phase transformation hysteresis loop. Two types of periodic response co-existence is also revealed in these regions. At the same time, in other frequency ranges the existence of additional modes of motion in the pseudoelastic oscillator can cause new large amplitude responses (both periodic and chaotic) to be generated, as well as eliminate some of the co-existing responses. Various bifurcation scenarios are constructed and the influence of the SMA element is discussed. To verify the obtained theoretical predictions, an experimental rig was designed and limited experimental studies have been conducted. The substantial response amplitude reduction at resonances has been captured, as well as the jumps to higher amplitude responses due to the softening behaviour of SMA. The numerical results appeared to be in a good agreement with the experimental data.
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Moreira, Maria Isabel Giusti. "Um modelo de sistema AVA-SMA orientado à legislação". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/171382.
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Dentro da Educação a Distância (EaD), os softwares de apoio como os Ambientes Virtuais de Aprendizagem (AVA) são considerados recursos que favorecem a comunicação entre os atores envolvidos, permitindo a troca de informação. Atribuir Inteligência Artificial a esses AVAs, utilizando Sistemas Multiagentes (SMA) e uma forma de procurar que os mesmos tenham um bom desempenho e que seus recursos facilitem o processo de aprendizagem. Esse trabalho cont em um estudo sobre os principais AVAs existentes e sobre os métodos alternativos de integração de AVA com SMA. Ao analisar o estado da arte dos AVAs pode-se observar que todos trabalham como ferramentas de auxílio ao aluno, por em nenhum deles trabalha aspectos da gestão da EaD dando suporte aos aspectos relevantes da legislação dessa modalidade. Por esse motivo, essa Tese tem por objetivo a criação de um modelo de integração AVA-SMA que possa tornar o AVA MOODLE capaz de auxiliar os gestores da EaD em suas diferentes tarefas, com base na incorporação, ao mesmo, de um modelo de representação de legislação. Para realizar essa integração do modelo AVA-SMA orientado a Legislação foi desenvolvido um espec co modelo organizacional de Sistema Multiagente. Por m com base em um estudo de caso, ser a realizado simulações para veri car as funcionalidades do Modelo de Sistema AVA-SMA orientado a Legislação, proposto nesta Tese.In Distance Learning (EaD), supporting software such as Virtual Learning Environments (VLE) are considered resources that favor communication between the actors involved, allowing the exchange of information. Assigning Arti cial Intelligence to these VLEs, using Multi-Agent Systems (MAS) is a way of ensuring they have a good performance and that its resources facilitate the learning process. This work contains a study on the major existing VLEs and on alternative methods to integrate VLE with MAS. When analyzing the state of the art of the VLEs it is possible to see that all of them work as aid tools for students, but none of them work on management aspects of distance learning that support the relevant aspects of the legislation for this type of education. Therefore, this thesis aims to create a VLE-MAS integration model that can make the VLE MOODLE able to help distance learning managers in their di erent tasks, based on incorporating a legislation representation model to it. To accomplish this integration of the legislation-oriented VLE-MAS model, a speci c Multi-Agent System organizational model was developed. At last, based on a case study, simulations will be conducted to verify the functionalities of the VLE-MAS System Model oriented to legislation, proposed in this thesis.
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Paine, Jeffrey S. "Multi-functional SMA hybrid composite materials and their applications". Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/38219.
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Shape memory alloy (SMA) materials such as nitinol have unique properties associated with the shape recovery effect and the material’s phase changes that have been used in a variety of actuator and sensing applications. By embedding SMA elements into host composite materials, control or modification of the SMA hybrid composite’s structural properties can be accomplished inservice, thereby increasing the hybrid composite’s structural functionality. Previous studies addressed increasing composite materials’ functionality by enabling in-service control of their dynamic response. Utilizing the SMA’s substantial recovery stress and capacity to dissipate strain energy to increase the hybrid composite’s static functionality is addressed herein. Specific applications for SMA hybrid composites include improving composite material’s impact damage resistance and composite cylinder stress and deflection control.
In stress and deflection control of cylindrical structures, SMA actuators are placed within the composite cylinder to form an active compound cylinder. The active SMA elements can significantly reduce the internal pressure-induced radial dilation and creep so that under severe loading, piston to cylinder tolerances may be maintained. Similar to a conventional metallic compound cylinder, the active compound cylinder also reduces peak cylinder hoop stresses. Hybridizing composites with nitinol improves their impact resistance because of nitinol’s tremendous capacity to absorb impact strain energy through the stress-induced martensitic phase transformation. The amount of impact damage is reduced and the material’s resistance to impact perforation at various velocities is improved. The experimental response of nitinol hybrid composites and the associated mechanics are presented. The unique toughness and resistance to permanent deformation that is a result of the stress-induced martensitic phase transformation enables the nitinol to absorb on the order of 4 times the strain energy of high alloy steel and 16 times that of many graphite/epoxy composites.
In most static applications where SMA elements are used for reinforcement, maintaining the integrity of the interface between the SMA elements and the host polymeric matrix composite material is critical to operation. The relationship between preparation of SMA elements for hybrid composite fabrication and interfacial bond strength is presented to address this issue. The mechanics of interfacial shear failure between SMA element and composite is also presented.Ph. D.
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Zhu, Shijie. "3D SMA Foams : Geometrical Reconstitution, Modelling and Numerical Simulation". Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0021.
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Un nouveau type de matériau cellulaire en Alliages à Mémoire de Forme possédant des caractéristiques intéressantes dues à la structure légère, super-élasticité et effet de mémoire de forme fait l’objet d’un intérêt croissant. L’objectif de la thèse est de concevoir la structure 3D de mousses en NiTi en utilisant des unités de cellules les plus représentatives de la microstructure du volume représentatif. Trois méthodes de reconstruction sont proposées : une reconstruction utilisant la méthode de Conception Assistée par Ordinateur, une reconstruction utilisant la méthode de tomodensitométrie et une méthode mixte. Des algorithmes de reconstruction intégrant les caractéristiques géométriques et les distributions aléatoires des cellulaires sont développés et intégrés dans une démarche de conception-modélisation avec adaptation de maillage. Les analyses numériques effectuées utilisent un modèle de comportement thermomécanique des AMF incluant l’effet de la transformation de phase, l’orientation martensitique et les mécanismes d’accommodation de macles afin de décrire la super-élasticité et l’effet mémoire de forme. Les effets de porosité, de taille, d’orientation et de dimensions des cellules à pores ouverts ou fermés sont étudiés. La technique d’homogénéisation basée sur le modèle de Mori-Tanaka est proposée. Des comparaisons avec les modèles CAO en terme de raideur et de transformation pour des mousses de porosité relativement faible <40% sont effectuéesCellular foams structures in Shape Memory Alloys (SMAs) are particularly interesting for their potential to provide superelasticity and shape memory effect in a lightweight material. The objective of the thesis is to design the 3D structure of NiTi foams using cell units most representative of the microstructure of the representative volume element. Three reconstruction methods are proposed: A reconstruction using the Computer Aided Design (CAD) method; a reconstruction using the tomodensitometry (CT) method and a mixed method CT-CAD. Reconstruction algorithms integrating random geometric characteristics and cell distributions are developed and integrated into a design-modeling approach with adaptive mesh. The numerical analyzes are performed on the reconstructed porous structure by using thermomechanical model of SMAs including phase transformation, martensitic orientation, and twin accommodation mechanisms describing superelasticity and Shape Memory Effect. The effects of porosity, size, orientation and cell dimensions on the super-elasticity of open and closed foams SMAs are studied numerically. The homogenization technique based on the Mori-Tanaka model is proposed to simulate the superelasticity behavior of homogeneous material. Comparisons with CAD models in terms of stiffness and transformation for relatively low porosity foams < 40% are performed
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Paine, Jeffrey Steven Nelson. "Multi-functional SMA hybrid composite materials and their applications /". This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-162936/.
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Liljeqvist, Björn. "StockholmsOperan, Galärvarvet : En smal sak". Thesis, KTH, Arkitektur, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37316.
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Galärvarvet är på många sätt en utmärkt plats för en ny och framträdande kulturbyggnad i Stockholm. Samtidigt utgöt operans komplexa och omfattande program en stor utmaning. I detta projekt löses konflikten mellan program och plats meddels en långsmal byggnad som bevarar naturvärden och rörelsemönster.Galarvarvet is in many ways an great site for a new and prominent cultural building in Stockholm. At the same time the complexity and size of the program of an opera poses a great challenge. In this project the conflict between program and site is solved with a stretched out building that preserves environmental values and movements.
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Hjalmarsson, Mariel y Mira Pavlovic. "Döden - En smak av livet". Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25949.
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Studiens syfte var att undersöka vad sjuksköterskorna på Hospice hade för uppfattningar om sin egen och patienternas död, samt om deras syn på döden förändrats genom yrkesgången. Undersökningen är en kvalitativ empirisk studie med inspiration av den fenomenografiska ansatsen som analysmodell. Fem semistrukturerade djupintervjuer har gjorts, som därefter transkriberats ordagrant. Utfallsrummet utgjorde åtta beskrivningskategorier. Studiens resultat visar att sjuksköterskornas uppfattningar om döden mest relateras till livet, hur de lärt sig att uppskatta sitt liv och hur de klarar av att arbeta med något så ångestladdat som döden.The purpose of this study was to examine the Hospice nurses perception of their own and the patients death and whether their work and perception of death have changed through the years. The study is qualitative empiric and is based on phenomenoraphy. Five semistructured interviews were conducted and transcribated verbatim. The outcome resulted into eight descriptive cathegories. The result shows that the nurses perception of death is mostly related to life, how they learned to appreciate their life and how they manage to work close to something as anxiety-ridden as death.
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Lindahl, Alexander y Joel Gustafsson. "Business Intelligence för små företag". Thesis, Uppsala universitet, Institutionen för informatik och media, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-386497.
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Globaliseringen av ekonomin har genererat globaliseringen av information som varje chef har att hantera snabbt och effektivt i beslutsprocessen. Små företag är mer sårbara för att ändra affärsvillkor än större konkurrenter. För att överleva i den instabila ekonomiska miljön där de är verksamma måste småföretag kunna monitorera sina affärer och använda alla sina resurser effektivt, särskilt informationsresurser. Under det senaste decenniet har användningen av business intelligence vuxit fram som ett måste för att inte tappa marknadsfördelar. Huvudsyftet med denna uppsats är att utvärdera hur business intelligence kan tas fram och implementeras i små företag. För att göra detta genomfördes ett design science research projekt där en IT- artefakt utvecklades med CRISP-DM som metod. Både IT-artefakten och metoden CRISP-DM utvärderas i uppsatsens analys. Arbetat mynnar ut i slutsatsen att CRISP-DM inte är lämpad som metod för denna typ av projekt. Slutligen kommer vi fram till de faktorer som härstammar från ett företags storlek som påverkar framtagningen av BI-system.
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Fuhnwi, Godwin Fonguh. "Computational modelling of a smart impeller actuated by shape memory alloys". Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1288.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011Smart (SMA-Shape Memory Alloy) Technology continues to advance rapidly as engineers move closer to and understand better the industrial and commercial needs for SMA. As a matter of fact, all types of products, which exercise some type of control over their function, are rapidly making their way into the marketplace [36] Nonetheless, nowhere has been evidence in the development of a SMA impeller. Unlike traditional impellers with no control over their function and sometimes fixed angle of attack, this paper demonstrates numerical investigations using analytical algorithms (Matrix laboratory programming and excel spread sheet) and advanced computer simulation package, Engineering Fluid dynamics (EFD) into the feasibility of using a smart impeller to study the performance of a pumping system and the best angle of attack for a Shape Memory Impeller. Primarily, Bench mark data and dimensions are obtained from a standard centrifugal pump run on a FM21 demonstration unit. Using the same standard centrifugal pump, and keeping all other dimensions the same but altering the angle of attack, EFD simulations where made. From analytical algorithm and EFD comparison, it was evident that the best angle of attack is 12 degree at the outlet angle with respect to the inlet angle. From EFD results, it is palpable that, by increasing the angle of attack from 35 degree to 45 degree at the outlet there will be huge increase in flow rate by 63.47% There is also a slight decrease in the impeller Torque from 35 degrees to 42 degrees by 0.72%. It is economically feasible to work at an outlet angle of 42 degrees due to increase in efficiency of 62.1% and a drop in torque of 0.72% by varying the outlet angle from 35 degrees to 42 degree. Understanding how critical actuator design is, it should be suggested that any shape memory impeller should never be used in critical components without a prior history of thermal and mechanical loading. Therefore, a NiTi impeller constitutive model can be designed, with impeller blades made from NiTi plates, trained to remember its best angle of attack (Martensitic phase). NiTi shape memory metal alloy (plates-blades) can exist in a two different temperature-dependent crystal structures (phases) called martensite [9](lower temperature-normal pumping condition) and austenite [9] (higher temperature or parent phase-trained best angle of attack.)
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Lequay, Victor. "Une approche ascendante pour la gestion énergétique d'une Smart-Grid : modèle adaptatif et réactif fondé sur une architecture décentralisée pour un système générique centré sur l'utilisateur permettant un déploiement à grande échelle". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1304.
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Le domaine de la gestion de l'énergie dans les smart grids a été largement exploré ces dernières années, de nombreuses approches différentes étant proposées dans la littérature. En collaboration avec notre partenaire industriel Ubiant, qui déploie des solutions d'optimisation énergétique du bâtiment, nous avons mis en évidence le besoin d'un système vraiment robuste et évolutif exploitant la flexibilité de la consommation résidentielle pour optimiser l'utilisation de l'énergie au sein d'une smart grid. Dans le même temps, nous avons observé que la majorité des travaux existants se concentraient sur la gestion de la production et du stockage et qu'aucune des architectures proposées n'étaient véritablement décentralisées. Notre objectif était alors de concevoir un mécanisme dynamique et adaptatif permettant de tirer parti de toute la flexibilité existante tout en garantissant le confort de l'utilisateur et une répartition équitable des efforts d'équilibrage ; mais aussi de proposer une plate-forme ouverte et modulaire avec laquelle une grande variété d'appareils, de contraintes et même d'algorithmes pourraient être interfacés. Dans cette thèse, nous avons réalisé (1) une évaluation des techniques actuelles de prévision de la consommation individuelle en temps réel, dont les résultats nous ont amenés à suivre (2) une approche ascendante et décentralisée pour l'ajustement diffus résidentiel reposant sur un mécanisme de compensation pour assurer un effacement stable. Sur cette base, nous avons ensuite construit (3) une plate-forme générique centrée sur l'utilisateur pour la gestion de l'énergie dans les réseaux intelligents, permettant une intégration aisée de plusieurs périphériques, une adaptation rapide à l'évolution de l'environnement et des contraintes, ainsi qu'un déploiement efficaceThe field of Energy Management Systems for Smart Grids has been extensively explored in recent years, with many different approaches being described in the literature. In collaboration with our industrial partner Ubiant, which deploys smart homes solutions, we identified a need for a highly robust and scalable system that would exploit the flexibility of residential consumption to optimize energy use in the smart grid. At the same time we observed that the majority of existing works focused on the management of production and storage only, and that none of the proposed architectures are fully decentralized. Our objective was then to design a dynamic and adaptive mechanism to leverage every existing flexibility while ensuring the user's comfort and a fair distribution of the load balancing effort ; but also to offer a modular and open platform with which a large variety of devices, constraints and even algorithms could be interfaced. In this thesis we realised (1) an evaluation of state of the art techniques in real-time individual load forecasting, whose results led us to follow (2) a bottom-up and decentralized approach to distributed residential load shedding system relying on a dynamic compensation mechanism to provide a stable curtailment. On this basis, we then built (3) a generic user-centered platform for energy management in smart grids allowing the easy integration of multiple devices, the quick adaptation to changing environment and constraints, and an efficient deployment
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Fernández, Villalba Omar A. y Salinas Edgardo G. Cáceres. "Evaluación del comportamiento mecánico de mezclas SMA y Superpave empleando asfalto modificado con Polímero SBS (Estireno-Butadieno-Estireno)". Bachelor's thesis, Universidad Ricardo Palma. Programa Cybertesis PERÚ, 2007. http://cybertesis.urp.edu.pe/urp/2007/fernandez_oa/html/index-frames.html.
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Filho, Cláudio Luiz Dubeux Neves. "Avaliação laboratorial de misturas asfálticas SMA produzidas com ligante asfalto-borracha". Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-18122015-105039/.
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As misturas asfálticas do tipo SMA apresentam granulometria descontínua, composta por uma maior fração de agregados graúdos, uma rica massa de ligante/fíler (mastique) e aproximadamente 4% de volume de vazios. Possuem um esqueleto pétreo de alta estabilidade devido ao contato pedra-pedra, que proporciona uma maior resistência à deformação permanente. Geralmente o teor de ligante asfáltico é superior a 6%, formando uma película asfáltica mais espessa. São utilizadas fibras para evitar o escorrimento do ligante durante as etapas de produção e lançamento e, geralmente, são usados asfaltos modificados por polímero. Esta pesquisa tem por objetivo avaliar se o ligante asfalto-borracha possibilita misturas asfálticas SMA capazes de atender aos valores limites de aceitação e, por meio de ensaios de laboratório (resistência à tração, módulo de resiliência, fadiga e deformação permanente em simulador de tráfego), comparar o comportamento de misturas SMA com diferentes tipos de ligante (asfalto convencional CAP 20, modificado por polímero e asfalto-borracha) com um concreto asfáltico convencional de granulometria contínua (Faixa C do DNER). Os resultados obtidos apresentam o comportamento de uma mistura SMA com asfalto-borracha muito mais próximo de misturas SMA produzidas com um ligante modificado por polímero do que com um asfalto convencional.SMA is a gap-graded asphalt mixture with a large proportion of high quality coarse aggregate, a high content of mastic (binder/filler), and approximately 4% of air voids. The larger proportion of coarse aggregate provides a greater stone-to-stone contact, which results in a mixture more resistant to permanent deformation than the conventional Hot Mix Asphalt (HMA). The asphalt content is typically greater than 6.0 percent, which increases the film thickness. Fibers are used to prevent drainage of the asphalt binder during the HMA production and placement, and polymer-modified asphalt cements are usually used. This research aims to evaluate if an asphalt-rubber binder produces SMA mixtures able to meet the technical requirements. The behavior of SMA mixtures produced with different binders (conventional AC-20, polymermodified, and asphalt-rubber) is analyzed based on laboratory tests (tensile strength, resilient modulus, fatigue, and permanent deformation in a traffic simulator) and compared to the behavior of a conventional dense-graded HMA The results show that the behavior of SMA mixtures produced with asphalt-rubber is much closer to SMA mixtures produced with polymer-modified binder than conventional asphalts.
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Chan, Y. B. "Molecular study of spinal muscular atrophy (SMA) using Drosophila melanogaster". Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270342.
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Pal, Anamitra. "Coordinated Control of Inter-area Oscillations using SMA and LMI". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/41229.
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The traditional approach to damp inter-area oscillations is through the installation of Power System Stabilizers (PSSs) which provide damping control action through excitation control systems of the generating units. However, study of recent blackouts has shown that the control action provided by a PSS alone is not sufficient for damping oscillations in modern power systems which operate under stressed conditions. An integrated form of control using remote measurements to coordinate the different control elements present in the system is the need of the hour.
One way of implementing such a coordinated control is through the development of a Linear Matrix Inequality (LMI)-based polytopic model of the system that guarantees pole placement for a variety of operating conditions. The size of the polytopic formulation is an issue for application of LMIs to large systems. The use of Selective Modal Analysis (SMA) alleviates this problem by reducing the size of the system. The previous attempts have used a model containing all the and modes, with SMA being used to eliminate all the other states. In practical applications the resulting system was still found to be too large to use in a polytopic model. This thesis presents an algorithm to reduce the size of the system to the relevant modes of oscillations.
A 16 machine, 68 bus equivalent model of the New England-New York interconnected power system is used as the test case with DC lines and SVCs acting as the control. The algorithm is then applied to a 127-bus equivalent model of the WECC System. The use of ESDs as a form of control is also demonstrated. The results indicate that the proposed control successfully damps the relevant modes of oscillations without negatively damping the other modes. The control is then transferred to a more detailed 4000+ bus model of the WECC system to realize its performance on real-world systems.Master of Science
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Li, Yinan. "Design and Analysis of Energy Harvesting with Shape Memory Alloy". University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1354872782.
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Billing, Mischa. "Spanska bubblor med smak av sommar". Örebro universitet, Restaurang- och hotellhögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-29873.
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Billing, Mischa. "Komplex smak av mörka mogna bär". Örebro universitet, Restaurang- och hotellhögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-29892.
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