Dissertations / Theses on the topic 'Adaptive Material'

Le besoin d'une très grande précision lors du traitement des matériaux par laser a fortement encouragé le développement des études de l'effet des impulsions ultra brèves pour la structuration des matériaux à une échelle micro et nano métrique. Une diffusion d'énergie minimale et une forte non linéarité de l'interaction permet un important confinement énergétique à des échelles les plus petites possibles. La possibilité d'introduire des changements de phases rapides et même de créer de nouveaux états de matière ayant des propriétés optimisées et des fonctions améliorées donne aux impulsions ultra brèves de sérieux arguments pour être utilisées dans des dispositifs très précis de transformation et de structuration des matériaux. L'étude de ces mécanismes de structuration et, en particulier, de leurs caractéristiques dynamiques, est une clé pour l'optimisation de l'interaction laser-matière suivant de nombreux critères utiles pour les procédés laser : efficacité, précision, qualité. Ce mémoire synthétise les travaux de l'auteur sur l'étude statique et dynamique du dépôt d'énergie ultra rapide, avec application aux procédés laser. La connaissance de la réponse dynamique des matériaux après irradiation laser ultra brève montre que les temps de relaxation pilotent l'interaction lumière-matière. Il est alors possible d'adapter l'énergie déposée à la réponse du matériau en utilisant les toutes récentes techniques de mise en forme spatio temporelle de faisceaux. Un couplage optimal de l'énergie donne la possibilité d'orienter la réponse du matériau vers un résultat recherché, offrant une grande flexibilité de contrôle des procédés et, sans doute, la première étape du développement de procédés « intelligents ».

This thesis reports on research to develop the first adaptive learning system for the Arabic language. The research also develops the first robust translation of the Felder-Soloman Index of Learning Styles (ILS) instrument into Arabic. Literal translation of the ILS applied to a pilot study resulted in lower internal validity in the instrument than found in the English language versions. The research discusses the development of a translation protocol undertaken to improve the validity and internal reliability of the Arabic version of the ILS. The new Arabic version of the Felder-Soloman Index of Learning Styles (ILS) instrument has been applied to two Arabic speaking groups in different Faculties at the King Abdul-Aziz University in Saudi Arabia: The Arts and Humanities Faculty and the Economics and Administration Faculty a total of 1204 students. Further analysis indicates that the Arabic version of the Felder-Soloman Index of Learning Styles (ILS) seems to be an appropriate psychometric instrument to identify learning styles in Arabic speaking communities. The second major part of the research was to use the Felder-Soloman Index of Learning Styles (ILS) instrument to develop an adaptive learning styles system and evaluate its effectiveness. The Teacher Assisting and Subject Adaptive Material System (TASAM) was tested out on different cohorts of students. Results showed that students taught using the learning style adaptive system performed significantly better in academic achievement than students taught the same material without adaptation to learning style. The feedback of student’s Survey overall students seemed to have enjoyed using the TASAM system and there seemed to have been a positive impact on learning performance. The thesis also provides guidance on translations of psychometric instrument and developing adaptive learning system.

The ability to distinguish between regions with different material properties is essential when numerically modelling many physical systems. Using a dual control volume mesh that avoids the problem of corner coupling, the HyperC face value scheme is extended to multiple dimensions and applied as a device for material advection on unstructured simplex meshes. The new scheme performs well at maintaining sharp interfaces between materials and is shown to produce small advection errors, comparable to those of standard material advection methods on structured meshes. To further minimise numerical diffusion of material interfaces a total variation bounded flux limiter, UltraC, is defined using a normalised variable diagram. Combining the material tracking scheme with dynamically adapting meshes, the use of a minimally dissipative bounded projection algorithm for interpolating fields from the old mesh to the new, optimised mesh is demonstrated that conserves the mass of each material. More generally, material conservation during the advection process is ensured through the coupling of the material tracking scheme to the momentum and mass equations. A new element pair for the discretisation of velocity and pressure is proposed that maintains the stability of the system while conserving the mass of materials. When modelling multiple materials the use of independent advection algorithms for each material can lead to the problem of non-physical material overlap. A novel coupled flux limiter is developed to overcome this problem. This automatically generalises to arbitrary numbers of materials. Using the fully coupled (and rigorously verified) multi-material model, several geophysically relevant simulations are presented examining the generation of waves by landslides. The model is validated by demonstrating close agreement between model predictions and experimental results of wave generation, propagation and run-up. The simulations also showcase the powerful capabilities of an unstructured, adaptive multi-material model in real world scenarios.

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-126).
One measure of performance in adaptive architecture is its ability the respond effectively to the environment and evolving program. As architects strive to create designs that respond to external change, more and more literally and actively, they are inevitably faced with the challenge of merging the kinetic with what is inherently an "immovable". Yet traditional mechanic devices allowing freedom of movement to an assembly have proven to be very expensive and often unreliable. This is in part due to their incompatibility with a building's use and lifespan. Thus, they are either implemented permanently at great expense or are confined to the temporary and architecturally limited realm of installations. We can thus witness a trend in architecture moving away from the mechanic and towards the use of material behavior and deformation as a cheaper and more durable architectural solution to responsiveness. Responsive materials such as shape memory alloys (SMA's) and electroactive polymers offer new possibilities for architecture. Furthermore, an understanding of the difference between kinetics in architecture and kinetics in mechanical objects has led to investigations into evolving interplays of rigidity and flexibility within structures. This thesis tries to advance the discourse by investigating the limits of elastic material deformation, and framing a niche where it is possible and fruitful for architecture to use material properties to produce adaptable space.
(cont.) The work instantiates these notions into a program of informal performance and exhibition space to test how performance criteria such as acoustical absorption, transmission and reflection, visual transparency and media proliferation at an architectural scale can be mediated by this approach.
by Andrey Dimitrov.
M.Arch.

Zur numerischen Simulation piezoelektrischer Probleme mit linearem Materialgesetz wird die adaptive Finite-Element-Methode genutzt. Bei der Lösung der entstehenden Gleichungssysteme vom Sattelpunktstyp wird auf eine Variante des Bramble-Pasciak-CG zurückgegriffen. Die Einbettung von Projektionstechniken in den Löser erlaubt eine Behandlung von verschiedenen Problembesonderheiten, speziell wird hier auf die Fälle konstanten Potentials auf Teilrändern sowie Kontaktprobleme an wachsenden Rissen eingegangen. Erste numerische Ergebnisse werden an einigen Beispielen demonstriert.

Exploring a space with our body is a strong experience; it is not like looking at a pic- ture of a space or listening to a detailed description of it. Being somewhere physically is a fundamental element involved in our unique and personal perception of a room. However, I often feel constrained by social and cultural rules in my bodily explora- tion of spaces. My aim throughout the project is to engage people into sharing their feelings and experiences about space, in order to better understand the relationship between the human body and the architecture in western societies. Through an experimental process I am articulating and reflecting upon a design meth- od to dialogue and engage with a large range of people. By using some tools from the field of interior architecture, I am building physical artefacts used as a means to challenge the bodily engagement of the users. The analysis of the interaction between the user and the artefacts, constituted the basis for me to elaborate on the two design proposals. The process also gives me the opportunity to reflect on my influence and responsibility as an interior architect into promoting, challenging and inviting people to more bodily engagement in space.

The full thesis contains copyrighted material which has been removed in the published version

The main focus of this work lies in the simulation of the deformation of mechanical components which consist of nonlinear elastic, incompressible material and that are subject to large deformations. Starting from a nonlinear formulation one can derive a discrete problem by using linearisation techniques and an adaptive mixed finite element method. This turns out to be a saddle point problem that can be solved via a Bramble-Pasciak conjugate gradient method. With some modifications the simulation can be improved.

The topic of this thesis is the numerical simulation of transversely isotropic 3D structures and laminates by means of the adaptive finite element method. To achieve this goal, the theoretical background of elastic deformation problems, transverse isotropy, plate theory, and the classical laminate theory is recapitulated. The classical laminate theory implies a combination of the membrane problem and the plate problem with additional coupling terms. The focus of this work is the adjustment of two integral parts of the adaptive FE algorithm according to the classical laminate theory. One of these parts is the solution of the FE system; a good preconditioner is needed in order to use the conjugate gradient method efficiently. It is shown via a spectral equivalence bound that the combination of existing preconditioners for the membrane and plate problems poses a capable preconditioner for the combined laminate problem. The other part is the error estimation process; the error estimator determines where the current mesh has to be refined for the next step. Existing results on residual error estimators for the elasticity problem, the biharmonic problem, and the plate problem are combined and extended to obtain a posteriori local residual error indicators for the classical laminate theory problem. The effectiveness of both results is demonstrated by numerical examples.

The ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) was held from 8-10 September 2014 in Newport, Rhode Island. The scope of the Conference covers intelligent, flexible, adaptive materials and systems that respond to changes in the environment to perform in the most profitable way. Scientific strides and technological maturity in the field are linked to the interdisciplinary efforts at universities, government and industry. SMASIS aims at assembling world experts across engineering and scientific disciplines such as mechanical, aerospace, electrical, materials, and civil engineering, as well as biology, physics and chemistry, to discuss the latest findings and trends in this fruitful area of research.

It has been known for decades that fatigue crack propagation in elastic-plastic media is very sensitive to load history since the nonlinear behavior of the material can have a great influence on propagation rates. However, the raw computation of millions of fatigue cycles with nonlinear material behavior on tridimensional structures would lead to prohibitive calculation times. In this respect, we propose a global model reduction strategy, mixing both the a posteriori and a priori approaches in order to drastically decrease the computational cost of these types of problems. First, the small scale yielding hypothesis is assumed, and an a posteriori model reduction of the plastic behavior of the cracked structure is performed. This reduced model provides incrementally the plastic state in the vicinity of the crack front, from which the instantaneous crack growth rate is inferred. Then an additional a priori model reduction technique is used to accelerate even more the time to solution of the whole problem. This a priori approach consists in building incrementally and without any previous calculations a reduced basis specific to the considered test-case, by extracting information from the evolving displacement field of the structure. Then the displacement solutions of the updated crack geometries are sought as linear combinations of those few basis vectors. The numerical method chosen for this work is the finite element method. Hence, during the propagation the spatial discretization of the model has to be updated to be consistent with the evolving crack front. For this purpose, a specific mesh morphing technique is used, that enables to discretize the evolving model geometry with meshes of the same topology. This morphing method appears to be a key component of the model reduction strategy. Finally, the whole strategy introduced above is embedded inside an adaptive approach, in order to ensure the quality of the results with respect to a given accuracy. The accuracy and the efficiency of this global strategy have been shown through several examples; either in bidimensional and tridimensional cases for model crack propagation, including the industrial example of a helicopter structure.

Thesis (Master of Architecture)--University of Cincinnati, 2009.
Advisor: Rebecca Williamson. Title from electronic thesis title page (viewed July 23, 2009). Includes abstract. Keywords: museums; curators; historic preservation; Washington, D.C.; adaptive reuse; commerce; museum display; exhibition design; material culture. Includes bibliographical references.

A new approach to the computation of the Limit load of a Von Mises rigid-plastic material structure modelled in plane stress is assessed. Most international design codes require the engineer to establish the safety of a structure for a given set of design loads under the so-called limit state conditions. The limit state represents the failure point at which the structure begins to exhibit unbounded deformations. Under limit state conditions, the deformation of the solids tend to concentrate on thin failure bands, known as slip-lines. This makes the finite element analysis a challenging task as the mesh needs to be adapted to capture these bands accurately. In order to achieve this, an adaptive technique is required whereby the error produced in each finite element is measured and if required the element is subdivided automatically. In order to measure this error both an upper and lower bound of the exact solution need to be evaluated. In this thesis, a novel technology to obtain the lower bound is derived and implemented together with mesh adaptivity technology. A lower bound is found from a state of stresses in equilibrium with the external forces. The proposed technique obtains such equilibrated state using the stresses obtained during the upper bound evaluation. These stresses, although not strictly in equilibrium, can be balanced using procedures available in the literature. The present aim of the research project is to develop numerical technology based on the finite element method to calculate the limit state of two-dimensional solids in plane stress. The upper bound theorem of limit analysis is implemented by means of a Lagrangian optimization technique solved by the Newton-Raphson method with Line Search. A control parameter to deal with the singularity of the tangent stiffness matrix due to the yielding condition is used along the range of admissible rate of deformations for a rigid-plastic material. The lower bound theorem is then applied by performing a technique to equilibrate the interelement tractions, kinematically solving a sequence of local problems using the equilibrated tractions as an updated load input, which lets us determine the elementwise contribution to both the upper and lower bounds. An adaptive technique is then implemented, based on the elemental contributions to the difference between the upper bound and the lower bound of the collapse multiplier. Both non-adaptive and adaptive results are evaluated. Results show a good performance of the solution technique, both in comparison with well known plane stress bound values and also in the graphical output obtained in the form of refined regions which describe the occurrence of slip-line patterns and/or localized yielding regions.

The application of static shape control was investigated in this thesis particularly for a composite plate configuration using piezoelectric actuators. A new electro-mechanically coupled mathematical model was developed for the analysis and is based on a third order displacement field coupled with a layerwise electric potential concept. This formulation, TODL, is then implemented into a finite element program. The mathematical model represents an improvement over existing formulations used to model intelligent structures using piezoelectric materials as actuators and sensors. The reason is TODL does not only account for the electro-mechanical coupling within the adaptive material, it also accounts for the full structural coupling in the entire structure due to the piezoelectric material being attached to the host structure. The other significant improvement of TODL is that it is applicable to structures which are relatively thick whereas existing models are based on thin beam / plate theories. Consequently, transverse shearing effects are automatically accounted for in TODL and unlike first order shear deformation theories, shear correction factors are not required. The second major section of this thesis uses the TODL formulation in static shape control. Shape control is defined here as the determination of shape control parameters, including actuation voltage and actuator orientation configuration, such that the structure that is activated using these parameters will conform as close as possible to the desired shape. Several shape control strategies and consequently algorithms were developed here. Initial investigations in shape control has revealed many interesting issues which have been used in later investigations to improve shape controllability and also led to the development of improved algorithms. For instance, the use of discrete actuator patches has led to greater shape controllability and the use of slopes and curvatures as additional control criteria have resulted in significant reduction in internal stresses. The significance of optimizing actuator orientation and its relation to piezoelectric anisotropy in improving shape controllability has also been presented. Thus the major facets of shape control has been brought together and the algorithms developed here represent a comprehensive strategy to perform static shape control.

The objective of this thesis is to prove, theoretically and empirically, the influence of the perceived quality of the building materials for residential use, in the determination of its estimated real estate value, for future calculation utilizing a comparison technique. To achieve this goal,we intend to develop an initial estimate to the synthetic index of the perceived quality of the building materials used in residencial , which will serve as a tool to facilitate and improve the actual calculation utilizing the comparison method in the real estate context. Currently, the valuation sciences don't consider a multidimensional indicator of materials in its calculations. This problem has a special impact when obtaining that valuation, making it difficult to evaluate if the objective quality of the materials and the subjective perception of the material's intrinsic quality are determinants of the real estate value. From this approach,the main hypothesis establishes preliminarily that the perceived quality of the material,as determined by suppliers and buyers, is a variable factor dependant of the complex interrelation of its aesthetical appeal,considering the acceptance level of the materials by the general public, and the technical level of the same, being the latter a factor dependant of its location in the dwelling. From this point of view, the investigation has been structured in two parts. In the first one, the bibliography section documents reference information found in articles ,thesis, magazines, related books and previous studies about the issue. With this material,the starting point is established for the development of this research work, addressing the theoretical argumentation,where the theory of value-utility is explained from the objective and subjective perspectives of the estimation of the real estate value. The second part has 2 stages: The first one tries to calculate the synthetic index of the perceived quality of interior finish materials utilizing the model of multi-variable Statistical Package for Social Sciences. Following this methodology, two different questionnaires have being designed, one for a sample of 400 users and another one for 35 building professionals, both performed during 2009 in Spain, specifically in the province of Alicante (Comunidad Valenciana). The second phase is focused in making a validation of the approximation to the synthetic index perceived during 2011. In this regard, it was considered appropriated start from a simple of 108 surveys for users and 101 surveys for experts in construction,both in the same location where the second part of the study was conducted.lt is important to remember that the method used for this last phase of the research was the Adaptative Conjoint Analys is with the propose of getting the general standardized valuation of partial utilities of the attributes associated with perception of the house's construction, when using the materials in floorings and vertical finishes based on maximization of demand preference. The two methodologies used in this second part are intended to find the distribution pattern of the perceived quality of building materials in residential use and see what the implicit weighs of the aesthetic appeal are as well as the technical quality of the material. This Doctoral Thesis allows the combination of two major lines of research,such as the discipline of building and the valuation sciences of real estate. For this reason, this Doctoral Thesis could be considered a pioneer study regarding to analysis of perception about the quality of the interior finish materials in residential use, for its subsequent application to the calculation of the estimate of the real estate value. In the case of our country, and especially in the province of Alicante, the results of this study can be considered as a channel of actualized information for the use of the building materials in the Levantine Architecture.
Esta tesis tiene como objeto fundamentar teórica y empíricamente la influencia de la calidad percibida de los materiales de construcción del uso residencial en la determinación de la estimación del valor de mercado, para su utilización posterior en la técnica de comparación.Para ello, se pretende diseñar una primera aproximación al índice sintético de la calidad percibida de los materiales en la edificación residencial,que sirva como herramienta para facilitar y mejorar la realidad de cálculo del método de comparación en el ámbito inmobiliario. Actualmente, la disciplina de la valoración no contempla en sus cálculos un indicador multidimensional de los materiales. Este problema tiene una especial incidencia en su obtención al imposibilitar evaluar si la calidad objetiva de los materiales y la percepción subjetiva de dicha calidad intrínseca, determinan el valor de mercado de los inmuebles. A partir de este planteamiento ,la hipótesis central postula de manera preliminar que la calidad percibida del material,tanto por oferentes como por demandantes, es un factor que depende de la interrelación compleja de su atractivo estético, teniendo en cuenta el nivel de aceptación de los materiales por la sociedad y la calidad técnica del mismo, siendo este último un factor dependiente de su localización en la vivienda. La investigación se ha estructurado en 2 apartados. En el primero, se establece la fase documental en donde se recopila la información encontrada en artículos, tesis, revistas, libros relacionados con el tema y estudios previos relacionados con el planteamiento del problema. De esta manera, se marca el punto de partida para el desarrollo de este trabajo de investigación y se aborda la argumentación teórica, en donde se expone la teoría del valor- utilidad des de la perspectiva objetiva y subjetiva de la estimación del valor de mercado. El segundo apartado se encuentra divido en dos etapas: En la primera, se trata de conseguir una aproximación al índice sintético de la calidad percibida respecto a los materiales en la edificación,siendo la técnica estadística multivariante con Statistical Package for Social Sciences la metodología utilizada para la investigación. A tales efectos ,se han diseñado 2 encuestas a partir de una muestra de 400 usuarios y 35 expertos en edificación durante el 2009, implementándose la investigación en España y más concretamente en la provincia de Alicante (Comunidad Valenciana). La segunda etapa se centra en realizar una validación de dicha aproximación al índice sintético de la calidad percibida durante el 2011. En este sentido, se consideró oportuno partir de una muestra de 108 encuestas para usuarios y 101 encuestas para expertos en edificación, realizadas ambas en la misma localización geográfica en donde se lleva a cabo la segunda parte del estudio. Cabe señalar que la metodología utilizada para esta última parte de la investigación ha sido la Adaptative Conjoint Analysis con el objetivo de obtener la valoración estandarizada general de las utilidades parciales de los atributos asociados a la percepción sobre los materiales de construcción del bien vivienda ,para uso de pavimentos y revestimientos verticales interiores, en base a la maximización de las preferencias de la demanda. Las 2 metodologías utilizadas tienen como finalidad el encontrar el patrón de distribución de la calidad percibida de los materiales de construcción en el uso residencial y ver cuáles son los pesos implícitos del atractivo estético y de la calidad técnica del material. En síntesis, la investigación permite aunar dos grandes líneas de investigación, como son la disciplina de los materiales de construcción y la disciplina de la valoración inmobiliaria.
La tesi di Dottorato che di seguito è presentata è stata sviluppata presso il Departamento de Tecnología de la Arquitectura (TA), della Escuela Técnica Superior de Arquitectura de Barcelona, nel programma di Dottorato in Gestión y Valoración Urbana y Arquitectónica presso la Universidad Politécnica de Cataluña. Questa tesi si propone di dimostrare, teoricamente ed empiricamente, l’influenza della qualità percepita dei materiali da costruzione ad uso residenziale nella determinazione della stima del valore di mercato, per un suo successivo utilizzo all’interno della stima comparativa. A questo fine è stato, prima di tutto, costruito un indice sintetico della qualità percepita dei materiali ad uso residenziale, che è servito come strumento per facilitare e migliorare la procedura estimativa basata sul principio comparativo in campo immobiliare. Attualmente, la disciplina della valutazione non include, all’interno delle sue procedure, un indicatore multidimensionale relativo alla qualità dei materiali. Questa mancanza ha un impatto notevole durante il processo di determinazione del valore di mercato di un immobile, sia da un punto di vista più oggettivo, sia dal lato della percezione soggettiva del consumatore. Coerentemente a questo primo obiettivo, l’ipotesi fondamentale è che la qualità percepita dei materiali di finitura sia, per i venditori come per gli acquirenti, un fattore che dipende – tenuto conto del livello di accettazione di un certo materiale da parte della società – dalla complessa interazione dell’aspetto estetico e della qualità tecnica, essendo quest’ultima un fattore legato, a sua volta, alla posizione di un materiale all’interno di un determinato ambiente, come, ad esempio, è quello domestico. La ricerca è stata strutturata in due principali sezioni. Nella prima, si stabilisce lo stato dell’arte e l’avanzamento della disciplina su questo argomento attraverso una documentazione costituita da articoli, lavori di tesi, riviste e testi relativi al contesto nazionale e internazionale. In questo modo, si pongono le basi per lo sviluppo del lavoro di ricerca e si affronta l’argomento da un punto di vista più teorico, rifacendosi alla teoria del valore-utilità in una prospettiva oggettiva/soggettiva La seconda sezione è suddivisa, a sua volta, in due parti: nella prima, si è cercato di ottenere un indice sintetico della qualità percepita dei materiali da costruzione attraverso una tecnica statistica multivariata, implementata per mezzo del software IBM-SPSS Statistics 20. A tal fine, si sono progettate due indagini, la prima basata su un campione di 400 utenti e 35 esperti in costruzioni, intervistati nel corso del 2009, implementando la ricerca in Spagna e in particolare nella provincia di Alicante (Comunità Valenciana); la seconda si è invece concentrata sulla validazione di questo primo approccio ed è stata sviluppata nel corso del 2011. A questo proposito, si è ritenuto opportuno partire da un campione di 108 interviste di utenti e da 101 interviste di esperti in costruzioni, entrambi localizzati nella stessa posizione geografica dell’analisi precedente. Questa volta, la metodologia utilizzata è stata tuttavia differente; si è scelto di impiegare la Adaptive Conjoint Analysis, che ha lo scopo di ottenere una valutazione standardizzata globale delle utilità parziali degli attributi associati alla percezione dei materiali da costruzione ad uso residenziale, per pavimentazione e finiture d’interni, basata sull’analisi delle preferenze dei consumatori. Le due metodologie utilizzate, in questa seconda fase, sono state scelte al fine di pervenire a un modello idoneo di valutazione della qualità percepita dei materiali da costruzione ad uso residenziale, calcolando i pesi impliciti del fattore estetico e della qualità tecnica dei singoli tipi di rivestimento. In sintesi, la ricerca consente di porre a confronto due aree disciplinari differenti, come la scienza dei materiali da costruzione e la valutazione immobiliare. Pertanto, essa potrebbe essere considerata come uno studio pilota con lo scopo di incentivare successive applicazioni basate sulla stima comparativa del valore di mercato. Nel caso del nostro paese e in particolare nel caso della provincia di Alicante, i risultati di questo studio potrebbero costituire una fonte di informazione aggiornata per l’utilizzo dei nuovi materiali da costruzione nell’architettura levantina.

The application of static shape control was investigated in this thesis particularly for a composite plate configuration using piezoelectric actuators. A new electro-mechanically coupled mathematical model was developed for the analysis and is based on a third order displacement field coupled with a layerwise electric potential concept. This formulation, TODL, is then implemented into a finite element program. The mathematical model represents an improvement over existing formulations used to model intelligent structures using piezoelectric materials as actuators and sensors. The reason is TODL does not only account for the electro-mechanical coupling within the adaptive material, it also accounts for the full structural coupling in the entire structure due to the piezoelectric material being attached to the host structure. The other significant improvement of TODL is that it is applicable to structures which are relatively thick whereas existing models are based on thin beam / plate theories. Consequently, transverse shearing effects are automatically accounted for in TODL and unlike first order shear deformation theories, shear correction factors are not required. The second major section of this thesis uses the TODL formulation in static shape control. Shape control is defined here as the determination of shape control parameters, including actuation voltage and actuator orientation configuration, such that the structure that is activated using these parameters will conform as close as possible to the desired shape. Several shape control strategies and consequently algorithms were developed here. Initial investigations in shape control has revealed many interesting issues which have been used in later investigations to improve shape controllability and also led to the development of improved algorithms. For instance, the use of discrete actuator patches has led to greater shape controllability and the use of slopes and curvatures as additional control criteria have resulted in significant reduction in internal stresses. The significance of optimizing actuator orientation and its relation to piezoelectric anisotropy in improving shape controllability has also been presented. Thus the major facets of shape control has been brought together and the algorithms developed here represent a comprehensive strategy to perform static shape control.

BACKGROUND:The origin of complex adaptations is one of the most controversial questions in biology. Environmental induction of novel phenotypes, where phenotypic retention of adaptive developmental variation is enabled by organismal complexity and homeostasis, can be a starting point in the evolution of some adaptations, but empirical examples are rare. Comparisons of populations that differ in historical recurrence of environmental induction can offer insight into its evolutionary significance, and recent colonization of North America by the house finch (Carpodacus mexicanus) provides such an opportunity.RESULTS:In both native (southern Arizona) and newly established (northern Montana, 18 generations) populations, breeding female finches exhibit the same complex adaptation - a sex-bias in ovulation sequence - in response to population-specific environmental stimulus of differing recurrence. We document that, in the new population, the adaptation is induced by a novel environment during females' first breeding and is subsequently retained across breeding attempts. In the native population, first-breeding females expressed a precise adaptive response to a recurrent environmental stimulus without environmental induction. We document strong selection on environmental cue recognition in both populations and find that rearrangement of the same proximate mechanism - clustering of oocytes that become males and females - can enable an adaptive response to distinct environmental stimuli.CONCLUSION:The results show that developmental plasticity induced by novel environmental conditions confers significant fitness advantages to both maternal and offspring generations and might play an important role not only in the successful establishment of this invasive species across the widest ecological range of extant birds, but also can link environmental induction and genetic inheritance in the evolution of novel adaptations.

The ability to programme and manipulate small changes at the molecular level to elicit a dramatically enhanced macroscopic response makes “stimuli-responsive” materials a fascinating topic of study. This work seeks to manipulate the solubility switch associated with polymers exhibiting a Lower Critical Solution Temperature without a temperature change (‘isothermally’). This concept, as overviewed in Chapter 1, has attractive applications in biological settings where variations in in vivo microenvironments may be used to produce increasingly targeted delivery vehicles, and to mediate cell membrane interactions. Using controlled radical polymerisation, pre-designed backbones, end-group(s) or side-chains can be targeted to control the hydrophilic-hydrophobic balance of a thermo-responsive system. Chapters 2 and 3 investigate this concept, using the chemical reduction of a functional polymer backbone or end-group to trigger isothermal polymer precipitation or solubilisation in linear and nanoparticle systems respectively. Chapter 4 applies a metal-ligand binding motif, prevalent in bacteria, to end-functional polymers as an alternative means of promoting isothermal polymer precipitation. This binding motif is then transferred to a nanoparticle system in Chapter 5, and used for the first time to prepare an optical, particle-based biosensor for the detection of physiologically relevant iron concentrations. Finally, Chapter 6 describes the enzymatic degradation of a polymer side-chain as a means of triggering isothermal precipitation and considers its potential to mediate cellular uptake. In summary, a series of functionalised polymers and nanoparticles have been synthesised and their (isothermal) responses characterised. These materials may have exciting potential in the emerging field of nanomedicine.

Adhesion between different objects is happening everywhere. Without it, simple procedures like walking or holding something in a hand or attaching a postage stamp would be impossible. The life itself depends on adhesion on all levels, starting from the interactions between the living cells. Adhesion between two substrates is a complex phenomenon, which at present is still not well understood. There are several factors determining the strength of adhesion: (i) molecular interactions at interface, (ii) mechanical properties of adhesive, and (iii) area of contact between adhesive and probing surface. Two surfaces are tacky when they possess the right balance between these factors. Controlling the adhesion of materials is important in many fields ranging from industrial purposes to biomedical applications and everyday usage. There is a demand for “smart” materials with integrated functionalities that make them responsive, switchable, biocompatible, anti-bacterial, more energy efficient, or autonomous. In particular, materials for such cutting-edge applications like cell culture, drug delivery, tissue engineering, biosensors, anti/biofouling, microfluidics, climbing robots, sport equipment and many others require adjustable/tuneable adhesive properties. Many efforts were directed towards fabrication of materials with either weak or strong adhesion depending on the field of application. However, design of “smart” surfaces with reversibly switchable/controllable adhesion is still a highly challenging task. Therefore, the thesis aims on design of smart polymeric materials with responsive / adaptive adhesion properties. For this, fabrication and investigation of two types of switchable polymer layers based on stimuli-responsive polymer brushes will be performed. The first group is dealing with thermoresponsive polymer brushes: poly-(N-isopropylacrylamide) and two types of biocompatible polyethylene glycol-based systems. These polymer layers undergo phase transition below and above LCST between hydrophilic and hydrophobic states. The second part of the work is related to solvent-responsive comb-like and block copolymer brushes consisted of hydrophilic PEG and hydrophobic PDMS biocompatible and biodegradable polymers.

A lack of separation of scales is the major hurdle hampering predictive and computationally tractable simulations of fracture over multiple scales. In this thesis an adaptive multiscale method is presented in an attempt to address this challenge. This method is set in the context of FE2 Feyel and Chaboche [2000] for which computational homogenisation breaks down upon loss of material stability (softening). The lack of scale separation due to the coalescence of microscopic cracks in a certain zone is tackled by a full discretisation of the microstructure in this zone. Polycrystalline materials are considered with cohesive cracks along the grain boundaries as a model problem. Adaptive mesh refinement of the coarse region and adaptive initiation and growth of fully resolved regions are performed based on discretisation error and homogenisation error criteria, respectively. In order to follow sharp snap-backs in load-displacement paths, a local arc-length technique is developed for the adaptive multiscale method. The results are validated against direct numerical simulation.

Nowadays, there is a growing demand for personalization and the "one-size-fits-all" approach for hypermedia systems is no longer applicable. Adaptive hypermedia (AH) systems adapt their behavior to the needs of individual users. However due to the complexity of their authoring process and the different skills required from authors, only few of them have been proposed. These last years, numerous efforts have been put to propose assistance for authors to create their own AH. However, as explained in this thesis some problems remain.In this thesis, we tackle two particular problems. A first problem concerns the integration of authors' materials (information and user profile) into models of existing systems. Thus, allowing authors to directly reuse existing reasoning and execute it on their materials. We propose a semi-automatic merging/specialization process to integrate an author's model into a model of an existing system. Our objectives are twofold: to create a support for defining mappings between elements in a model of existing models and elements in the author's model and to help creating consistent and relevant models integrating the two models and taking into account the mappings between them.A second problem concerns the adaptation specification, which is famously the hardest part of the authoring process of adaptive web-based systems. We propose an EAP framework with three main contributions: a set of elementary adaptation patterns for the adaptive navigation, a typology organizing the proposed elementary adaptation patterns and a semi-automatic process to generate adaptation strategies based on the use and the combination of patterns. Our objectives are to define easily adaptation strategies at a high level by combining simple ones. Furthermore, we have studied the expressivity of some existing solutions allowing the specification of adaptation versus the EAP framework, discussing thus, based on this study, the pros and cons of various decisions in terms of the ideal way of defining an adaptation language. We propose a unified vision of adaptation and adaptation languages, based on the analysis of these solutions and our framework, as well as a study of the adaptation expressivity and the interoperability between them, resulting in an adaptation typology. The unified vision and adaptation typology are not limited to the solutions analysed, and can be used to compare and extend other approaches in the future. Besides these theoretical qualitative studies, this thesis also describes implementations and experimental evaluations of our contributions in an e-learning application.

Adaptive control of cutting process using as initial data information signals of various physical natures, characterizing indirectly quality of part cutting. The article demonstrates that among a variety of information signals the cutting sound is the most informative. Firstly, it is registered in a contactless manner, making it noise-resistant to spurious signals generated by operating of a metalcutting tool, and secondly, the cutting sound originating at the point of contact of the tool and the workpiece, has high sensitivity to tool wear and roughness of the machined surface. Further research should focus on the development of processing quality-forecasting methods to promptly change the cutting modes and therefore prolong the period of the defect-free part processing.

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第13930号
人博第403号
新制||人||99(附属図書館)
19||人博||403(吉田南総合図書館)
UT51-2008-C846
京都大学大学院人間・環境学・環境学研究科相関環境学専攻
(主査)教授 加藤 真, 教授 松井 正文, 准教授 市岡 孝朗, 教授 堀 道雄
学位規則第4条第1項該当

An optical computer which performs the classification of an input object pattern into one of two learned classes is designed and demonstrated. The classifier is an optical implementation of a neural network model of computation featuring learning, self-organization, and decision-making competition. Neural computation is discussed including models for learning networks and motivation for optical implementation. A discussion of photorefractive crystal holographic storage and adaptation is presented followed by experimental results of writing and erasing gratings in several different crystals. The optical network features a photorefractive crystal to store holographic interconnection weights and an opto-electronic circuit to provide a means of competitive decision making and feedback. Results of the optical learning network and its operation as an associative memory are followed by extensions of the architecture to allow improved performance and greater flexibility.

With the variability in performance of the multitude of parallel environments available today, the conceptual overhead created by the need to anticipate runtime information to make design-time decisions has become overwhelming. Performance-critical applications and libraries carry implicit assumptions based on incidental metrics that are not portable to emerging computational platforms or even alternative contemporary architectures. Furthermore, the significance of runtime concerns such as makespan, energy efficiency and fault tolerance depends on the situational context. This thesis presents a case study in the application of both Mattson’s prescriptive pattern-oriented approach and the more principled structured parallelism formalism to the computational simulation of inelastic neutron scattering spectra on hybrid CPU/GPU platforms. The original ad hoc implementation as well as new patternbased and structured implementations are evaluated for relative performance and scalability. Two new structural abstractions are introduced to facilitate adaptation by lazy optimisation and runtime feedback. A deferred-choice abstraction represents a unified space of alternative structural program variants, allowing static adaptation through model-specific exhaustive calibration with regards to the extrafunctional concerns of runtime, average instantaneous power and total energy usage. Instrumented queues serve as mechanism for structural composition and provide a representation of extrafunctional state that allows realisation of a market-based decentralised coordination heuristic for competitive resource allocation and the Lyapunov drift algorithm for cooperative scheduling.

Composite materials are increasingly being used in advanced structural ap- plications. Debonding of adjacent laminate layers, also known as delamination, is considered to be one of the most dominant damage mechanisms affecting the behavior of composite laminates. Various numerical methods for simulating delamination in composite materials do exist, but they are generally limited to small-scale structures due to their complexity and high numerical cost. In this thesis, a novel technique aimed to allow efficient simulation of delamination in large-scale laminated composite structures is presented. During the transient analysis, continuum elements within regions where delamination has the potential to initiate are adaptively split through their thickness into two shell elements sandwiching a cohesive element. By elimi- nating the a priori requirement to implant cohesive elements at all possible spatial locations, the computational efforts are reduced, thus lending the method suitable for treatment of practical size structures. The methodol- ogy, called the local cohesive zone method (LCZ), is verified here through its application to Mode-I, Mode-II and Mixed-Mode loading conditions, and is validated using a dynamic tube-crushing loading case and plate impact events. Good agreement between the numerical results and the available experimental data is obtained. The results obtained using the LCZ method are compared favourably with the numerical results obtained using the con- ventional cohesive zone method (CZM). The numerical performance of the method and its efficiency is investi- gated. The efficiency of the method was found to be superior compared to that of the conventional CZM, and was found to increase with increasing model size. The LCZ method is shown to have a lower effect on reducing the structural stiffness of the structure, compared to the conventional CZM. The results obtained from the application of the LCZ method to the various cases tested are encouraging, and prove that the local and adaptive insertion of cohesive zones into a finite element mesh can effectively capture the delamination crack propagation in laminated composite structures. It is expected that further improvements in speed and accuracy will be attained once the algorithm is embedded within commercial finite element solvers as a built-in feature.
Applied Science, Faculty of
Graduate

Les propriétés thermomécaniques étonnantes des alliages à mémoire de forme (AMF) sont mises à profit dans de nombreux domaines. Ce matériau est capable de mettre en mouvement une structure suite à un changement de température. Or les façades de bâtiments contemporains, pour s’adapter à des conditions climatiques variables, doivent réguler le passage de la lumière et de l’énergie thermique, par exemple au moyen de systèmes motorisés. Le potentiel de fils AMF pour l’actionnement de protections solaires en façade est exploré ici. La modélisation du couplage mécanique induit par l’introduction de tels matériaux dans une structure a été peu étudiée : l’AMF agit sur la structure qui en retour modifie le comportement de l’AMF. La première étape de ce travail a consisté en une contribution à la modélisation du comportement thermomécanique de ce matériau reposant sur le choix d’une énergie libre, d’un potentiel de dissipation et de plusieurs variables internes. Deux modèles unidimensionnels ont été proposés : un premier modèle monocristallin reproduit de façon simplifiée le comportement du matériau, et un second modèle polycristallin propose une description plus fidèle. En parallèle un dispositif d’essai original à température contrôlée a été développé, il a permis une caractérisation fiable de fils Nickel-Titane et l’identification des paramètres des modèles. Dans un second temps ces modèles ont permis de résoudre des cas de couplage élémentaires (fil AMF + ressort, lame élastique + fil AMF noyé) pour des chargements thermomécaniques simples, et des solutions analytiques ont été établies. Les modèles ont été implémentés numériquement via un script matériau utilisateur (UMAT) pour le logiciel éléments finis ABAQUS et au moyen d’un algorithme d’optimisation sous contraintes. Ceci permet de simuler la réponse couplée de systèmes structuraux a priori quelconques intégrant des AMF, connectés à ou noyés dans, une structure. Dans un troisième temps, divers actionneurs ont été conçus, réalisés et testés dans le cadre de l’occultation solaire des façades. Le principe est d’utiliser un cycle de température permettant à l’AMF de déformer la structure, puis à l’énergie élastique de déformation de la structure d’assurer le retour à la forme originale. Le comportement réel de ces actionneurs a été comparé aux calculs analytiques et éléments finis. Des tests cycliques ont également été réalisés
The surprising thermomechanical properties of shape memory alloys (SMA) are harnessed in many engineering fields. This material is able to set a structure in motion upon a temperature change. Today, contemporary building facades must adapt to variable climate conditions as well as to evolving building use and occupancy. In particular, they must regulate light and thermal energy passing through the facade, with motorized systems, for example. We explore the potential of SMA wires for putting in motion solar shading devices in facades. The modelling of the mechanical coupling induced by the introduction of such materials in a structure has received little attention as of now. The SMA acts on the structure which in return modifies the SMA behavior. The first step of this work is a contribution to modelling the thermomechanical behavior of this material through the choice of a free energy, a dissipation potential and internal variables. We propose two one-dimensional models: a first monocrystalline model reproduces the material behavior in a simplified way, and a second polycrystalline model offers a more accurate description of it. An original temperature-controlled testing apparatus was developed in parallel. This led to a reliable characterization of Nickel-Titanium wires and the identification of the model parameters. In a second stage, these models allowed to solve elementary coupling cases (SMA wire + Spring, Elastic plate + Embedded SMA wire) for simple thermomechanical loadings and we established analytical solutions. The models were then numerically implemented via a user-material script (UMAT) for the finite elements software ABAQUS, by using a constrained optimization algorithm. This enables the simulation of the coupled response of, in principle, any structural system including SMA wires, connected or embedded in the structure. Finally, we designed, fabricated and tested different actuators in the context of sunlight control in facades. The working principle lies in using a temperature cycle which allows the SMA to deform the structure, and then allows the elastic strain energy in the structure to ensure the return to the original shape. The real behavior of these actuators have been compared to analytical and finite element calculations. We also performed cyclic tests

This research addresses the issues of adaptation and personalisation of the computer interface for Web-based learning materials taking into consideration key characteristics of learners and particularly their cognitive style. The thesis examines main concerns driving learning towards individualisation. Different approaches to adaptation and personalisation are analysed, as are a range of adaptive systems. The need for further research regarding individual differences is identified; it is argued that cognitive styles should be allowed for in designing adaptive learning materials. A comprehensive review of cognitive style classifications is presented, from which key defining attributes and advantageous instructional conditions are identified and a number of adaptive variables derived. LEARNINT, a prototype based on these variables was developed and used in two experimental studies. Results show a relationship between Interface Affect and learning outcomes and also between the variables underpinning the interface style used and variation in user reactions and performance; however, little interaction is observed between these variables and cognitive style. It is suggested that for most learners using Web-based learning materials performance may improve if they experience positive affect towards the interface; also, that the proposed variables stand as good candidates for providing adaptivity. A methodological approach is presented that extends the functionality of LEARNINT. The generic aspects of the research are further elaborated offering guidance on future directions for the design of adaptive Web-based learning materials.

The 2015 ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS) was held from 21 to 23 September 2015, in Colorado Springs, Colorado. The scope of the conference covers intelligent, flexible, adaptive materials and systems that respond to changes in the environment to perform in the most profitable way. Scientific strides and technological maturity in the field are linked to the interdisciplinary efforts at universities, government and industry. SMASIS aims at assembling world experts across engineering and scientific disciplines such as mechanical, aerospace, electrical, materials, and civil engineering, as well as biology, physics and chemistry, to discuss the latest findings and trends in this fruitful area of research.

An adaptive arbitrary-order curvilinear progressive 2D crack growth algorithm is presented. The method uses the ZFEM hypercomplex finite element program to compute arbitrary order derivatives of strain energy with respect to self-similar or perpendicular crack extensions, and then constructs a family of Taylor series functions of strain energy versus crack growth direction. An adaptive algorithm automatically selects the best high-degree polynomial to extrapolate a curvilinear crack path, and adjusts the length of the crack growth increment added during each simulation step to maintain the crack path and model energy within desired tolerances. The method is automated such that the full crack path from inception to failure is computed with multiple FE analyses. Numerical examples up to fifth order are presented and compared against experiments.