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.

La simulation multi-agent représente une solution pertinente pour l’ingénierie et l’étude des systèmes complexes dans de nombreux domaines (vie artificielle, biologie, économie, etc.). Cependant, elle requiert parfois énormément de ressources de calcul, ce qui représente un verrou technologique majeur qui restreint les possibilités d'étude des modèles envisagés (passage à l’échelle, expressivité des modèles proposés, interaction temps réel, etc.).Parmi les technologies disponibles pour faire du calcul intensif (High Performance Computing, HPC), le GPGPU (General-Purpose computing on Graphics Processing Units) consiste à utiliser les architectures massivement parallèles des cartes graphiques (GPU) comme accélérateur de calcul. Cependant, alors que de nombreux domaines bénéficient des performances du GPGPU (météorologie, calculs d’aérodynamique, modélisation moléculaire, finance, etc.), celui-ci est peu utilisé dans le cadre de la simulation multi-agent. En fait, le GPGPU s'accompagne d’un contexte de développement très spécifique qui nécessite une transformation profonde et non triviale des modèles multi-agents. Ainsi, malgré l'existence de travaux pionniers qui démontrent l'intérêt du GPGPU, cette difficulté explique le faible engouement de la communauté multi-agent pour le GPGPU.Dans cette thèse, nous montrons que, parmi les travaux qui visent à faciliter l'usage du GPGPU dans un contexte agent, la plupart le font au travers d’une utilisation transparente de cette technologie. Cependant, cette approche nécessite d’abstraire un certain nombre de parties du modèle, ce qui limite fortement le champ d’application des solutions proposées. Pour pallier ce problème, et au contraire des solutions existantes, nous proposons d'utiliser une approche hybride (l'exécution de la simulation est partagée entre le processeur et la carte graphique) qui met l'accent sur l'accessibilité et la réutilisabilité grâce à une modélisation qui permet une utilisation directe et facilitée de la programmation GPU. Plus précisément, cette approche se base sur un principe de conception, appelé délégation GPU des perceptions agents, qui consiste à réifier une partie des calculs effectués dans le comportement des agents dans de nouvelles structures (e.g. dans l’environnement). Ceci afin de répartir la complexité du code et de modulariser son implémentation. L'étude de ce principe ainsi que les différentes expérimentations réalisées montre l'intérêt de cette approche tant du point de vue conceptuel que du point de vue des performances. C'est pourquoi nous proposons de généraliser cette approche sous la forme d'une méthodologie de modélisation et d'implémentation de simulations multi-agents spécifiquement adaptée à l'utilisation des architectures massivement parallèles. / Multi-Agent Based Simulations (MABS) represents a relevant solution for the engineering and the study of complex systems in numerous domains (artificial life, biology, economy, etc.). However, MABS sometimes require a lot of computational resources, which is a major constraint that restricts the possibilities of study for the considered models (scalability, real-time interaction, etc.).Among the available technologies for HPC (High Performance Computing), the GPGPU (General-Purpose computing on Graphics Processing Units) proposes to use the massively parallel architectures of graphics cards as computing accelerator. However, while many areas benefit from GPGPU performances (meteorology, molecular dynamics, finance, etc.). Multi-Agent Systems (MAS) and especially MABS hardly enjoy the benefits of this technology: GPGPU is very little used and only few works are interested in it. In fact, the GPGPU comes along with a very specific development context which requires a deep and not trivial transformation process for multi-agents models. So, despite the existence of works that demonstrate the interest of GPGPU, this difficulty explains the low popularity of GPGPU in the MAS community.In this thesis, we show that among the works which aim to ease the use of GPGPU in an agent context, most of them do it through a transparent use of this technology. However, this approach requires to abstract some parts of the models, what greatly limits the scope of the proposed solutions. To handle this issue, and in contrast to existing solutions, we propose to use a nhybrid approach (the execution of the simulation is shared between both the processor and graphics card) that focuses on accessibility and reusability through a modeling process that allows to use directly GPU programming while simplifying its use. More specifically, this approach is based on a design principle, called GPU delegation of agent perceptions, consists in making a clear separation between the agent behaviors, managed by the processor, and environmental dynamics, handled by the graphics card. So, one major idea underlying this principle is to identify agent computations which can be transformed in new structures (e.g. in the environment) in order to distribute the complexity of the code and modulate its implementation. The study of this principle and the different experiments conducted show the advantages of this approach from both a conceptual and performances point of view. Therefore, we propose to generalize this approach and define a comprehensive methodology relying on GPU delegation specifically adapted to the use of massively parallel architectures for MABS.

Spinal muskelatrofi (SMA) är en ärftlig sjukdom där nedbrytning av nervceller leder till muskelförtvining. I Sverige föds fyra till åtta barn varje år med SMA Typ 1. Tidigare forskning har varit inriktad på palliativ vård då barnen inte överlevt sin tvåårsdag. Ett nytt läkemedel har nu utvecklats som förlänger barnens liv. Detta ger familjer hopp samtidigt som de ställs inför nya utmaningar. Det saknas forskning om hur föräldrar till ett barn med SMA Typ 1 som behandlas med det nya läkemedlet nusinersen upplever sin vardag, därför är det viktigt att uppmärksamma detta ämne. Syftet med studien var att belysa vardagslivet för två mammor till barn med SMA Typ 1. Studien genomfördes genom narrativ analys av en podcast. Resultatet mynnade ut i fem teman: Ögonblicket när livet förändras, Att bli expert på sitt barns komplexa omsorgsbehov, Hemmet som arbetsplats, En vardag som pendlar mellan ljus och mörker och En vardag som präglas av en oviss framtid. Från resultatet framkom det att föräldrar som har ett barn med SMA Typ 1 lever i en emotionell och krävande vardag. Det är av vikt att föräldrar får stöd och avlastning för att bibehålla sin hälsa och orka hålla hela livet. Sjuksköterskans kunskap om sjukdomen behöver ökas. Ett bra bemötande av sjuksköterskan anses viktigt för att undvika frustration och skapa en förtroendefull vårdrelation. Det finns ett behov av att utveckla ett journalsystem med gemensamma och lättåtkomliga journaler för alla vårdinstanser som kan underlätta för sjuksköterskan i mötet med dessa föräldrar. Föräldrar har ett behov av att veta mer om sina barns framtidsutsikter varpå vidare studier föreslås.

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Shape memory alloys (SMAs) possess the unique ability to change their shape by undergoing a solid-state phase transformation at a particular temperature. The shape change is associated with a large strain recovery as the material returns to its "remembered" shape. Their ability to act as both sensor and actuator has made them an attractive subject of study for numerous applications. SMAs have many characteristics which are advantageous in space-related applications, including generation of large forces associated with the strain recovery, smooth and controlled movements, large movement to weight ratio, high reliability, and spark-free operation. The objective of this work is the further development and testing of a cryogenic thermal conduction switch as part of NASA funded projects. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the methane temperature. Development of the switch concept has been continued in this work by utilizing Ni-Ti-Fe as the active SMA element. Ni-Ti-Fe exhibits the shape memory effect at cryogenic temperatures, which makes it well suited for low temperature applications. This alloy is also distinguished by an intermediate phase change known as the rhombohedral or R-phase, which is characterized by a small hysteresis (typically 1-2 deg C) and offers the advantage of precise control over a set temperature range. For the Ni-Ti-Fe alloy used, its thermomechanical processing, subsequent characterization using dilatometry and differential scanning calorimetry and implementation in the conduction switch configuration are addressed. This work was funded by grants from NASA KSC (NAG10-323) and NASA GRC (NAG3-2751).

In NiTi, a reversible thermoelastic martensitic transformation can be induced by temperature or stress between a cubic (B2) austenite phase and a monoclinic (B19') martensite phase. Ni-rich binary compositions are cubic at room temperature (requiring stress or cooling to transform to the monoclinic phase), while Ti-rich binary compositions are monoclinic at room temperature (requiring heating to transform to the cubic phase). The stress induced transformation results in the superelastic effect, while the thermally induced transformation is associated with strain recovery that results in the shape memory effect. Ternary elemental additions such as Fe can additionally introduce an intermediate rhombohedral (R) phase between the cubic and monoclinic phase transformation. This work was initiated with the broad objective of connecting the macroscopic behavior in shape memory alloys with microstructural observations from transmission electron microscopy (TEM). Specifically, the goals were to examine (i) the effect of mechanical cycling and plastic deformation in superelastic NiTi; (ii) the effect of thermal cycling during loading in shape memory NiTi; (iii) the distribution of twins in martensitic NiTi-TiC composites; and (iv) the R-phase in NiTiFe. Both in situ and ex situ lift out focused ion beam (FIB) and electropolishing techniques were employed to fabricate shape memory alloy samples for TEM characterization. The Ni rich NiTi samples were fully austenitic in the undeformed state. The introduction of plastic deformation (8% and 14% in the samples investigated) resulted in the stabilization of martensite in the unloaded state. An interlaying morphology of the austenite and martensite was observed and the martensite needles tended to orient themselves in preferred orientations. The aforementioned observations were more noticeable in mechanically cycled samples. The observed dislocations in mechanically cycled samples appear to be shielded from the external applied stress via mismatch accommodation since they are not associated with unrecoverable strain after a load-unload cycle. On application of stress, the austenite transforms to martensite and is expected to accommodate the stress and strain mismatch through preferential transformation, variant selection, reorientation and coalescence. The stabilized martensite (i.e., martensite that exists in the unloaded state) is expected to accommodate the mismatch through variant reorientation and coalescence. On thermally cycling a martensitic NiTi sample under load through the phase transformation, significant variant coalescence, variant reorientation and preferred variant selection was observed. This was attributed to the internal stresses generated as a result of the thermal cycling. A martensitic NiTi-TiC composite was also characterized and the interface between the matrix and the inclusion was free of twins while significant twins were observed at a distance away from the matrix-inclusion interface. Incorporating a cold stage, diffraction patterns from NiTiFe samples were obtained at temperatures as low as -160ºC. Overall, this work provided insight in to deformation phenomena in shape memory materials that have implications for engineering applications (e.g., cyclic performance of actuators, engineering life of superelastic components, stiffer shape memory composites and low-hysteresis R-phase based actuators). This work was supported in part by an NSF CAREER award (DMR 0239512).

In the range of 25°C - 80°C (ultra-low grade heat), a large quantity of waste heat from various processes is available unused. Special alloys made of nickel and titanium, so-called Shape Memory Alloys (SMA), could be an alternative technology to Organic Rankine Cycles to make this energy usable in the low power range. The 'THEAsmart 2' research project is therefore investigating the service life and energy lifecycle of this material to test the benefits of shape memory alloys in energy recovery and the efficiency levels that can be achieved. To this end, a demonstration prototype is being built that converts thermal energy into rotary motion. The next step is to link the demonstration prototype with a conventional fluid pump to create an SMA fluid pump that is driven by the thermal energy of the fluid to be pumped. The advantage of such a pump would be that it would be energy-independent, i.e. it would be operated solely by the thermal energy of the fluid without an electrical connection. Furthermore, such a pump could contribute to energy savings if it is used in cooling circuits in which the thermal energy of the fluid is the waste product from another process. In this case, it replaces an electric pump and utilizes the 'waste product' heat. The aim of the project is to investigate how and whether coil springs made of shape memory alloy are suitable for energy recovery. This is considered via the energy lifecycle: if more energy is required to manufacture a spring than this spring can convert kinetic energy from thermal energy in its lifecycle, then its use for energy recovery does not make sense in principle. As a secondary result of this research, statements about the efficiency of shape memory alloy coil springs and statements about their service life are expected.

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