Dissertations / Theses on the topic 'Property propagation'

Rapid development in nanofabrication has led to the design of new materials with very unusual properties. The exhibition of negative and zero indices of refraction are among the most striking properties of these materials, which have become the focus of intensive research worldwide. The potential for applications that is possible due to the new light manipulation capabilities of these materials has been the driving force behind this research. Most of the research in this field has primarily been experimental while the theoretical studies have mainly been limited to computer modeling, which in itself is a challenging problem. This research requires considerable computational resources and the development of new computer algorithms.The origin of the unusual properties in these materials comes from the combination of dielectric host materials with metallic nanosructures. These materials are often referred to as nanocomposite metamaterials. The plasmonic resonance in properly engineered metallic nanostructures gives rise to the resonant interaction of the incident electromagnetic field with metamaterials in such a way as to stimulate a magnetic permeability and an electric permittivity with negative real parts. The resonant nature of this phenomenon leads to considerable losses in metamaterials, which has made the study of loss compensation one of the key subjects in this field.The two techniques of loss compensation in metamaterials are considered in this dissertation. One of these techniques consists of doping the host material with active atoms. In the second technique, loss compensation is achieved by embedding these active atomic inclusions directly into the nanostructures. This dissertation presents the derivation of the systems of governing equations and studies the coherent pulse amplification for both cases.

High cycle fatigue tests were carried out on a medium strength continuous casting AA 5754 Al alloy, and new generation high strength AA 2026 and AA 2099 Al alloys. The effect of texture on fatigue properties and short crack behavior were studied. The strengthening mechanisms were also thoroughly investigated for the two high strength alloys.Texture played an important role in the anisotropy of fatigue strength for the AA 5754 Al alloy. Being a solution strengthened alloy, it had a fatigue strength of 120% σy. High strength Al alloys had a strong tendency for planar slip due to the high density of coherent and shearable precipitates in the alloys. Texture was a key factor controlling the crack initiation and propagation. The crack path and the possible minimum twist angles were measured using EBSD and calculated theoretically by a crystallographic model. Based on the micro-texture measured by EBSD, the crack paths were predicted for the AA 2099 alloy and confirmed by the observed values.The excellent balance of superior fatigue properties and high tensile strength of AA 2026 and AA 2099 was attributed to the reduced population of Fe-containing particles, homogeneously distributed precipitates and dislocations. The addition of Zr coupled with the optimized thermo-mechanical treatment strongly restrained the recrystallization, refined the grain structure and promoted the homogenization of the precipitates. Moreover, the retainment of the deformation texture developed during the hot extrusion provided significant orientation strengthening in the high strength Al alloys.Fatigue cracks tended to initiate at coarse second phase particles on sample surfaces and the crack population varied markedly with the applied stresses in the high strength Al alloys. The relationship between of the crack population and the applied stress level was studied and quantified by a Weibull distribution function. Since the measured cracknumbers were associated with the crack initiate sites (i.e., the weakest links) in an alloy, the fatigue weakest-link density, which is defined as the crack population per unit area when stress close to the ultimate tensile stress, and the weakest-link strength distribution can all be calculated and regarded as a property of the studied materials.

En raison du grand nombre de graphes de connaissances et, surtout, de leurs interconnexions encore plus nombreuses à l'aide de la propriété owl:sameas, il est devenu de plus en plus évident que cette propriété est souvent mal utilisée. En effet, les entités liées par la propriété owl:sameas doivent être identiques dans tous les contextes possibles et imaginables. Dans les faits, ceci n'est pas toujours le cas et induit une détérioration de la qualité des données. L'identité doit être considérée comme étant dépendante d'un contexte. Nous avons donc proposé une étude à large échelle sur la présence de la sémantique dans les graphes de connaissances, puisque certaines caractéristiques sémantiques permettent justement de déduire des liens d'identités. Cette étude nous a amenés naturellement à construire une ontologie permettant de donner la teneur en sémantique d'un graphe de connaissances. Nous avons aussi proposé une approche de liage de données fondée à la fois sur la logique permise par les définitions sémantiques, et à la fois sur la prédominance de certaines propriétés pour caractériser la relation d'identité entre deux entités. Nous nous sommes aussi intéressés à la complétude et avons proposé une approche permettant de générer un schéma conceptuel afin de mesurer la complétude d'une entité. Pour finir, à l'aide des travaux précédents, nous avons proposé une approche fondée sur les plongements de phrases permettant de calculer les propriétés pouvant être propagées dans un contexte précis. Ceci permet l'expansion de requêtes SPARQL et, in fine, d'augmenter la complétude des résultats de la requête
Due to a large number of knowledge graphs and, more importantly, their even more numerous interconnections using the owl:sameas property, it has become increasingly evident that this property is often misused. Indeed, the entities linked by the owl:sameas property must be identical in all possible and imaginable contexts. This is not always the case and leads to a deterioration of data quality. Identity must be considered as context-dependent. We have, therefore, proposed a large-scale study on the presence of semantics in knowledge graphs since specific semantic characteristics allow us to deduce identity links. This study naturally led us to build an ontology allowing us to describe the semantic content of a knowledge graph. We also proposed a interlinking approach based both on the logic allowed by semantic definitions, and on the predominance of certain properties to characterize the identity relationship between two entities. We looked at completeness and proposed an approach to generate a conceptual schema to measure the completeness of an entity. Finally, using our previous work, we proposed an approach based on sentence embedding to compute the properties that can be propagated in a specific context. Hence, the propagation framework allows the expansion of SPARQL queries and, ultimately, to increase the completeness of query results

This research consists of two main parts: development of a rock expert system (RES) as an easy-to-use and effective tool for evaluating rock properties, and modification and utilization of the three-dimensional Particle Flow Code (PFC3D) to analyze rock behavior. Because of different reasons, it is often difficult to obtain the rock property values directly. As an alternative, typical values and empirical correlations are often used to evaluate the rock property values. However, the typical values and empirical correlations come in various forms and are scattered in different sources. It is often difficult, time-consuming or even impossible for an engineer to find appropriate information to estimate the required rock properties. So in the first part of the research, the RES was developed as an easy-to-use and effective tool for evaluating rock properties by conducting detailed review and evaluation of well determined values and empirical correlations of rock properties in the published literature, and developing a central database and data application tools. The study of RES demonstrates the storage of rock property values and correlations is strongly applicable and the web based data application tool is effective to use and easy expandable. Considering its granular nature, the discrete element method (DEM) has been widely adopted to analyze the mechanical behavior of rock. The Particle Flow Code (PFC) is one of the most popular DEM softwares. The basic idea of PFC is to treat rock as an assembly of bonded particles that follow the law of motion and consider the model behavior dominated by the formation and interaction of micro cracks developed within the particle-particle cement (bond). Unlike the continuum methods, PFC can deal with the natural process from micro cracking to macro failure, without predefining a failure criterion for the rock. However, there are still issues related to the application of PFC to analyze different rock problems. For example, so far, most of the studies use PFC2D although many of the problems are three dimensional and should be better simulated with PFC3D. It is also found that the simulations using the default PFC parallel bond model extremely underestimate the ratio of unconfined compressive strength to tensile strength (UCS/T). So in the second part of the research, the important aspects related to the application of PFC3D, including model scale, particle size distribution and contact model, were studied, a new contact model was developed for addressing the limitation of the default PFC3D on obtaining unrealistically low UCS/T ratios, and finally the new contact model was used to investigate rock fracture initiation and propagation.

Pour des raisons autant écologiques qu'économiques ou techniques, des huiles de base d'esters naturels ont été utilisées pour remplacer de l'huile minérale dans les appareillages basse et moyenne tensions. Ce travail consiste en étude de caractérisation d'un mélange des esters naturels de faible viscosité (RS50) basant sur l'huile de colza pour les applications dans les transformateurs haute tension. L'influence des facteurs humidité, température, teneur en particules ainsi que vieillissement thermique sur ses propriétés diélectriques telles que : permittivité, conductivité, pertes et rigidité électrique sous tension alternative a été mise en évidence. La RS50 présente une solubilité de l'eau élevée, la conductivité, la permittivité et les pertes plus élevées que celles de l'huile minérale mais ces différences sont réduites dans des huiles vieillies. Sa rigidité électrique en tension alternative est similaire à l'huile minérale, même après le vieillissement. Pourtant, une analyse des phénomènes de préclaquage et de claquage dans des configurations particulières ont montré que les esters naturels sont moins favorables pour les applications à haute tension que l'huile minérale. Parallèlement, des études méthodologiques ont été effectuées. L'intérêt d'une application de la méthode de mesure spectroscopique fréquentielle à la caractérisation des isolants liquides est la mise en évidence et la validité des conditions de mesure de la rigidité électrique du liquide isolant, ce qui est traditionnellement imposé suivant les normes, a été discutée
For the environmental, economic or technical reasons, oils based on natural esters were used to replace mineral oil in electrical equipments in low and medium voltage. This work consists on characterization of a mixture (RS50) of low viscosity natural esters based on rapeseed oil for applications in high voltage transformers. The influence of humidity, temperature, particle content and thermal aging on its dielectric properties such as permittivity, conductivity, losses and electrical strength was highlighted. The RS50 has a high-water solubility, its conductivity, permittivity and losses are both higher than those of mineral oil but these differences are reduced in aged oils. Its electrical strength is similar to mineral oil even after aging. However, an analysis more precise of prebreak down and breakdown phenomena in specific configurations have shown that natural esters are less favorable for high voltage applications than mineral oil. In parallel, a methodological study was carried out. Advantage of using the frequency spectroscopy measuring method for the characterization of insulating liquids is highlighted. The validity of conditions for the dielectric strength measurement in the liquid insulation, which is traditionally imposed following the standards, was also discussed

Increasing societal demand for automation has led to considerable efforts to control large-scale complex systems, especially in the area of autonomous intelligent control methods. The control system of a large-scale complex system needs to satisfy four system level requirements: robustness, flexibility, reusability, and scalability. Corresponding to the four system level requirements, there arise four major challenges. First, it is difficult to get accurate and complete information. Second, the system may be physically highly distributed. Third, the system evolves very quickly. Fourth, emergent global behaviors of the system can be caused by small disturbances at the component level. The Multi-Agent Based Control (MABC) method as an implementation of distributed intelligent control has been the focus of research since the 1970s, in an effort to solve the above-mentioned problems in controlling large-scale complex systems. However, to the author's best knowledge, all MABC systems for large-scale complex systems with significant uncertainties are problem-specific and thus difficult to extend to other domains or larger systems. This situation is partly due to the control architecture of multiple agents being determined by agent to agent coupling and interaction mechanisms. Therefore, the research objective of this dissertation is to develop a comprehensive, generalized framework for the control system design of general large-scale complex systems with significant uncertainties, with the focus on distributed control architecture design and distributed inference engine design. A Hybrid Multi-Agent Based Control (HyMABC) architecture is proposed by combining hierarchical control architecture and module control architecture with logical replication rings. First, it decomposes a complex system hierarchically; second, it combines the components in the same level as a module, and then designs common interfaces for all of the components in the same module; third, replications are made for critical agents and are organized into logical rings. This architecture maintains clear guidelines for complexity decomposition and also increases the robustness of the whole system. Multiple Sectioned Dynamic Bayesian Networks (MSDBNs) as a distributed dynamic probabilistic inference engine, can be embedded into the control architecture to handle uncertainties of general large-scale complex systems. MSDBNs decomposes a large knowledge-based system into many agents. Each agent holds its partial perspective of a large problem domain by representing its knowledge as a Dynamic Bayesian Network (DBN). Each agent accesses local evidence from its corresponding local sensors and communicates with other agents through finite message passing. If the distributed agents can be organized into a tree structure, satisfying the running intersection property and d-sep set requirements, globally consistent inferences are achievable in a distributed way. By using different frequencies for local DBN agent belief updating and global system belief updating, it balances the communication cost with the global consistency of inferences. In this dissertation, a fully factorized Boyen-Koller (BK) approximation algorithm is used for local DBN agent belief updating, and the static Junction Forest Linkage Tree (JFLT) algorithm is used for global system belief updating. MSDBNs assume a static structure and a stable communication network for the whole system. However, for a real system, sub-Bayesian networks as nodes could be lost, and the communication network could be shut down due to partial damage in the system. Therefore, on-line and automatic MSDBNs structure formation is necessary for making robust state estimations and increasing survivability of the whole system. A Distributed Spanning Tree Optimization (DSTO) algorithm, a Distributed D-Sep Set Satisfaction (DDSSS) algorithm, and a Distributed Running Intersection Satisfaction (DRIS) algorithm are proposed in this dissertation. Combining these three distributed algorithms and a Distributed Belief Propagation (DBP) algorithm in MSDBNs makes state estimations robust to partial damage in the whole system. Combining the distributed control architecture design and the distributed inference engine design leads to a process of control system design for a general large-scale complex system. As applications of the proposed methodology, the control system design of a simplified ship chilled water system and a notional ship chilled water system have been demonstrated step by step. Simulation results not only show that the proposed methodology gives a clear guideline for control system design for general large-scale complex systems with dynamic and uncertain environment, but also indicate that the combination of MSDBNs and HyMABC can provide excellent performance for controlling general large-scale complex systems.

La quantification et la propagation des incertitudes dans les modèles physiques apparaissent comme des voies essentielles vers l'amélioration de la prédiction de leur réponse. Le développement d'outils de modélisation des incertitudes et d'estimation de leur impact sur la réponse d'un modèle a constitué un axe de recherche privilégié dans de nombreux domaines scientifiques. Cette dernière décennie, un intérêt croissant a été porté à des méthodes numériques basées sur une vision fonctionnelle des incertitudes. Ces méthodes, couramment baptisées ``méthodes spectrales stochastiques'', sont issues d'un mariage fructueux de l'analyse fonctionnelle et de la théorie des probabilités.

Reposant sur des bases mathématiques fortes, les méthodes spectrales de type Galerkin semblent constituer une voie prometteuse pour l'obtention de prédictions numériques fiables de la réponse de modèles régis par des équations aux dérivées partielles stochastiques (EDPS). Plusieurs inconvénients freinent cependant l'utilisation de ces techniques et leur transfert vers des applications de grande taille : le temps de calcul, les capacités de stockage mémoire requises et le caractère ``intrusif'', nécessitant une bonne connaissance des équations régissant le modèle et l'élaboration de solveurs spécifiques à une classe de problèmes donnée. Un premier volet de mes travaux de recherche a consisté à proposer une stratégie de résolution alternative tentant de lever ces inconvénients. L'approche proposée, baptisée méthode de décomposition spectrale généralisée, s'apparente à une technique de réduction de modèle a priori. Elle consiste à rechercher une décomposition spectrale optimale de la solution sur une base réduite de fonctions, sans connaître la solution a priori.

Un deuxième volet de mes activités a porté sur le développement d'une méthode de résolution d'EDPS pour le cas où l'aléa porte sur la géométrie. Dans le cadre des approches spectrales stochastiques, le traitement d'aléa sur l'opérateur et le second membre est en effet un aspect aujourd'hui bien maîtrisé. Par contre, le traitement de géométrie aléatoire reste un point encore très peu abordé mais qui peut susciter un intérêt majeur dans de nombreuses applications. Mes travaux ont consisté à proposer une extension de la méthode éléments finis étendus (X-FEM) au cadre stochastique. L'avantage principal de cette approche est qu'elle permet de traiter le cas de géométries aléatoires complexes, tout en évitant les problèmes liés au maillage et à la construction d'espaces d'approximation conformes.

Ces deux premiers volets ne concernent que l'étape de prédiction numérique, ou de propagation des incertitudes. Mes activités de recherche apportent également quelques contributions à l'étape amont de quantification des incertitudes à partir de mesures ou d'observations. Elles s'insèrent dans le cadre de récentes techniques de représentation fonctionnelle des incertitudes. Mes contributions ont notamment porté sur le développement d'algorithmes efficaces pour le calcul de ces représentations. En particulier, ces travaux ont permis la mise au point d'une méthode d'identification de géométrie aléatoire à partir d'images, fournissant une description des aléas géométriques adaptée à la simulation numérique. Une autre contribution porte sur l'identification de lois multi-modales par une technique de représentation fonctionnelle adaptée.

Dans une modélisation intégrée des impacts, l'objectif est de tester plusieurs scénarios d'entrées de modèle et/ ou d'identifier l'effet de l'incertitude des entrées sur les sorties de modèle. Dans les deux cas, un grand nombre de simulations de modèle sont nécessaires. Cela reste bien évidemment infaisable avec un modèle de Chimie-Transport à cause du temps CPU demandé. Pour surmonter cette difficulté, deux approches ont été étudiées dans cette thèse. La première consiste à construire un modèle réduit. Deux techniques ont été utilisées : la première est la méthode POD (Proper Orthogonal Decomposition) liée au comportement statistique du système. La seconde méthode est une méthode efficace de prétabulation fondée sur la troncature d'un développement multivariables de la relation Entrées/ sorties associé au modèle. La seconde est relative à la réduction du nombre de simulations demandé par la méthode Monte-Carlo classique de propagation d'incertitude. La technique utilisée ici est basée sur une représentation d'une sortie de modèle incertaine comme un développement de polynômes orthonormaux de variables d'entrées. Un autre point clé dans la modélisation intégrée d'impacts est de développer des stratégies de réduction des émissions en calculant des matrices de transfert sur plusieurs années de simulation. Une méthode efficace de calcul de ces matrices a été ainsi développée, notamment en définissant des scénarios "chimiquement" représentatifs. L'ensemble de ces méthodes a été appliqué au modèle POLAIR3D, modèle de Chimie-Transport développé dans le cadre de cette thèse

Dans une modélisation intégrée des impacts, l'objectif est de tester plusieurs scénarios d'entrées de modèle et/ ou d'identifier l'effet de l'incertitude des entrées sur les sorties de modèle. Dans les deux cas, un grand nombre de simulations de modèle sont nécessaires. Cela reste bien évidemment infaisable avec un modèle de Chimie-Transport à cause du temps CPU demandé. Pour surmonter cette difficulté, deux approches ont été étudiées dans cette thèse : La première consiste à construire un modèle réduit. Deux techniques ont été utilisées : la première est la méthode POD (Proper Orthogonal Decomposition) liée au comportement statistique du système. La seconde méthode est une méthode efficace de prétabulation fondée sur la troncature d'un développement multivariables de la relation Entrées/ sorties associé au modèle.
La seconde est relative à la réduction du nombre de simulations demandé par la méthode Monte-Carlo classique de propagation d'incertitude. La technique utilisée ici est basée sur une représentation d'une sortie de modèle incertaine comme un développement de polynômes orthonormaux de variables d'entrées. Un autre point clé dans la modélisation intégrée d'impacts est de développer des stratégies de réduction des émissions en calculant des matrices de transfert sur plusieurs années de simulation. Une méthode efficace de calcul de ces matrices a été ainsi développée, notamment en définissant des scénarios "chimiquement" représentatifs.
L'ensemble de ces méthodes a été appliqué au modèle POLAIR3D, modèle de Chimie-Transport développé dans le cadre de cette thèse.

This Thesis is devoted to the study of two different aspects of electron behavior in two-dimensional materials, namely hydrodynamic electron transport and plasmon propagation. The Thesis is structured as follows. In Chapter 1 the main experimental facts that motivated our work on electron hydrodynamics and plasmonics are presented and critically discussed. Chapter 2 contains our main results on hydrodynamic electron transport. After deriving the basic equations of the electron hydrodynamics and discussing their limit of applicability, we use them to quantify the impact of two different transport coffcients, the shear and Hall viscosities of the electron liquid, on steady-state transport. Our results are used to propose experimental protocols that allow an experimental determination of these transport coeffcients. Chapter 3 deals with plasmon propagation through inhomogeneous media. We consider three dfferent geometries: an interface between two dfferent materials, a one dimensional perturbation, and a zero dimensional perturbation in an otherwise uniform electron system. We calculate scattering observables for plasmons in these geometries. For the interface geometry we also investigated the presence of plasmonic bound states localized near the interface, while for the second and third geometries we quantify the impact of non-local fects. Chapter 4 presents a theory of chiral plasmons in materials with a non-trivial Berry curvature in the electronic band structure. We firstly employ the results of Chapter 3 to obtain a semi-classical theory of Chiral Berry Plasmons (CBPs) at a generic interface between two materials having different Berry uxes across the Fermi surface. We then test the impact of different types of screened electron-electron interaction, and of a finite damping rate on the dispersion and lifetime of CBPs.

Tissue healing is in general a complex process, which involves both local and systemic responses, and bone regeneration in particular is much slower than repair in any other human tissue. Thus, it exhibits a great challenge in clinical practice and in the field of research. Bone regeneration is comprised of a series of biological events, involving a number of cell types and intracellular and extracellular molecular- signaling pathways, with a definable temporal and spatial sequence, in an effort to optimize the skeletal repair and restore its functionality. Photobiomodulation (PBM) therapy has been shown to be effective in modulating both local and systemic responses, by enhancing cellular activities resulting in an increase in function, especially in injured tissues, leading to optimization of tissue repair and regeneration. In bone tissue, application of the photonic energy leads to bone healing by the activation of osteoblasts, leading to proliferation and differentiation, as well as osteoclast inhibition and, consequently, neoformation of bone matrix. The process of the in vitro pre-osteoblasts maturation, mimicking their in vivo behavior, passes through three distinct stages of development: proliferation, early differentiation (maturation) and late differentiation (mineralization). Despite the extensive research on the effects of photobiomodulation (PBM) light on bone regeneration, the current outcomes ranging from positive to negative effect remain controversial. These contradictory data are thought to be due to; incomplete knowledge and understanding of the mechanistic effects of laser light on cells, lack of standardized laser dosimetry, inefficient laser beam profile, improper study design and varied methods of investigation. The literature is hindered by a considerable heterogeneity of the irradiation parameters of PBM, as well as, the methods utilized to evaluate the results and the type of osteoblast-like cells irradiated. This has led to a need of standardization. Moreover, heterogeneity of the current studies and their limitations could be due to study designs and inefficient beam profile, resulting in undesirable effects and accounting for negative and inconclusive outcomes. Ultimately, lack of intimate knowledge and understanding of the PBM light behavior impinging on the target tissue, as well as the optical tissue properties, can compromise optimization of the therapeutic outcomes. Thus, an evidence-based decision for definite therapeutic application of PBM in bone regeneration is required. In this thesis, we addressed the above issues and challenges via two elements, the electromagnetic (EM) modeling experiments and the molecular and cellular impact of PBM on bone regeneration (In vitro studies). The Electromagnetic models In my PhD proposal, I intended to both create an EM model, for the first time, and examine the mechanism of interaction of the electromagnetic fields (EMFs) with cells/tissues and establish the link that can be utilized in my cellular experiments. As the project evolved, it became clear this work was breaking new grounds and was significantly more complex than initially envisaged. As it is a small part of a much larger exciting project undertaken by University of Genoa, it has meant that I need to coordinate my work with the overall timetable of this larger project. As a result, I decided to defer, the interaction of the EMF with cells of interest part, to my Post doctorate study. We developed, for the first time, a set of simple models to examine the behavior of the local electromagnetic field (EMF), determining the PBM effects on mitochondria. This set of models was tested and crosschecked for its validity by evaluating various variables in terms of, polarization, absorption and scattering coefficient, dissipated energy density and irradiance, as well as the refractive index. Ultimately, our model and preliminary data are the first stepping-stone for further experiments, in order to understand the mechanism of interaction between electromagnetic fields and cells or tissues. Our conclusions showed that when these set of models are utilized, for the phenomenon of interest, the incident field polarization had small effects on the electromagnetic field and negligible consequences on the average energy, as well as, on the dissipated power densities. The same was shown to hold true for different orientations that the mitochondria can assume. The analogous conclusions were obtained by taking into account the possible changes in the dimensions or of the real part of the refractive index of the considered organelles. The variations of the absorption coefficient were shown to have significant effects on the average dissipated power density in the mitochondria but these effects can be predicted in a surprisingly simple way. It was proved that the numerical analysis, of the problems of interest, could be computed by using three-dimensional models, involving only a few mitochondria in the plane, which was transverse to the direction of propagation of the illuminating light that generated a uniform distribution of the energy over 1cm2 area. The one- dimensional models provided significant information on the EMF, utilized to stimulate the mitochondria. Mitochondria behaved like weak scatterers. Therefore, it was not necessary to analyze large extension of such organelles to understand what happen inside one of them. The molecular and cellular impact of 980nm PBM on osteoblast maturation: in vitro studies Our pilot study data, on the bone marrow stromal cells (BMSCs), strongly suggested that the high fluence concept (over 60J/cm2 in continuous emission mode (CW)) delivered by flattop beam profile device (FT) can promote BMSCs differentiation towards osteogenesis. Moreover, the results showed an increase in cytokines synthesis with potent anti-inflammatory properties and a decrease in the release of proinflammatory mediators. This provided me with a platform, demonstrating the validity of high fluence in facilitating osteoblasts differentiation through BMSCs. Based on this; I formulated three PBM protocols for 980nm to be tested on pre- osteoblast cell line in my definitive in vitro studies. The first phase of in vitro studies aimed to evaluate the 980nm bio-stimulatory effects on osteoblasts maturation, optimise the PBM effects on bone healing with various beam profiles delivery devices, and establish protocol/protocols of 980nm PBM in bone regeneration. The primary objective was to determine the optimal 980nm dosimetry, which exerts bio- stimulatory effects to accelerate and enhance the bone regenerative process. The secondary objective was to evaluate the intra-cellular pathways of the photon-cell interaction across the metabolic proliferative and differentiation changes, which ultimately lead to bone healing and repair. The results of this study validated the contribution of PBM in bone regeneration and elucidated the biochemical effects at a cellular level. Moreover, the role of different dosages of 980nm PBM irradiation delivered by FT; in comparison to the Gaussian beam profiles (Standard (ST)) on bone regeneration were highlighted. The setup of the power outputs on the laser device was 1.1Watt (W) for the ST and 1W for the FT. However, the real (the threshold) power output reaching the target, measured by power meter, was as ∼0.9 W, (Irradiance ∼ 0.9W/cm2, Exposure time 60 seconds, energy ∼55 J (Joule), fluence ∼55 J/cm2) delivered with the FT beam profile in CW in comparison to the ST, on MC3T3-E1 pre-osteoblast maturation. The protocol was based on 60 seconds exposure time for two consecutive weeks, which employed for all the groups. The laser grouping and their associated irriadtied energies were as follows: Group 1- Irradiation once per week (Total enrgy 110J). Group 2- Irradiation three times per week (Alternate day) (Total energy 330J). Group 3 - irradiation five- times per week (Total energy 550 J). The control cultures were processed in identical conditions except that the laser device was kept off all the time. The total energy was 0J.
The metabolic activity and the osteoblasts maturation were analyzed by alkaline phosphatase assay, alizarin red S histological staining, immunoblot and/or double immunolabeling analysis for Bcl2, Bax, Runx-2, Osx, Dlx5, osteocalcin, and collagen Type 1. Our data, for the first time, prove that laser irradiation of 980 nm wavelength with flattop beam profile delivery system, compared to standard-Gaussian profile, has improved photobiomodulatory efficacy on pre-osteoblastic cells differentiation. Mechanistically, the irradiation enhances the pre-osteoblast differentiation through activation of Wnt signaling as well as the Smads 2/3-βcatenin pathway. Our results indicated and valued the intra-cellular pathways of the photon-cell interaction across the metabolic, proliferative and differentiation changes in the cells. Additionally, our data showed that the cells irradiated THREE times a week (Total energy of 330 J) and ONCE a week (Total energy of 110 J) for two consecutive weeks protocols have increased the proliferation and differentiation of the osteoblasts in both ST & FT hand-pieces but the data showed increasingly statistical significant in the FT group. The only Runx2 was detected when the cells were irradiated with the ST hand-piece. Therefore, total energy of 110 J when either of the hand-pieces utilized, has influenced early differentiation markers. Interestingly, when the process was carried out, until the mineralization and maturation (Late osteogenesis), the ST hand-piece irradiation failed to induce an effective process, and did not lead to matrix deposition, while the FT profile showed a significant effect. In conclusion, our data, for the first time, prove that laser irradiation of 980 nm wavelength with the FT beam profile delivery system in comparison to the ST profile has a great photobiomodulatory efficacy on pre-osteoblastic cells differentiation, which would assist in accelerating bone regeneration, due to its homogeneous energy distribution at each point of its cross-section. Moreover, the irradiation protocols of three times a week and once a week for two consecutive weeks were able to increase the pre-osteoblasts and osteoblasts transcription factors, which were strongly and statistically significantly increased when the FT hand-piece was utilized. Therefore, the 980 nm laser irradiation protocol was able to promote the MC3T3-E1 cell differentiation. Researchers have demonstrated that the major barrier for an effective biological healing is insufficient laser photonic energy delivered to the injured site. PBM can modify the cell metabolism by increasing the mitochondria's ATP production. Currently, the challenge is to understand the target tissues optical properties and its cellular pathway when irradiated with laser phonic energy. In this way, modification of various energy exposure values can influence clinical outcomes predictability. Therefore, in the second phase of my in vitro study, we evaluated the effect of 980nm irradiation delivered with ST and FT beam profile hand-pieces on monolayer cell, at various power outputs; 0.8W, 0.5W and 0.25W. However, the exact power output values reaching the target, measured by power meter, were as follows: 0.75W, 0.45W, and 0.20W respectively. The MC3T3-E1 cells irradiated for two consecutive weeks, according to the following protocols: once a week (Total energy 90, 54, 24 J), respectively); three times a week (total energy 270, 162, 72J, respectively); five times a week (total energy 450, 270, 120 J, respectively). Metabolic activity of viable cells evaluated as follows: Hoechst staining; Western blotting for Runx-2, Bcl2, Bax, Osx, Dlx5, β-catenin, Smads 2/3, TGFβ, p.PI3K, PI3K, p.AKt, AKt, and p.ERK. Our data, for the first time, prove that the 980 nm irradiation at power output setting at 0.75W (0.75W/cm2) for 60 seconds in CW stimulated the MC3T3-E1 pre- osteoblasts viability, by affecting the critical pre-survival markers such as p.PI3K, p.Akt, Bcl2 and Bclxl. Moreover, we concluded that 980nm PBM delivered with FT at 0.75W power output was comparable to results with the ST. However, 0.45W and 0.20W did not modulate the cell metabolic features. Additionally, none of the laser protocols delivered with FT or ST had any influence on the cell differentiation process. In summary, our in vitro studies data, for the first time, have demonstrated the potential of utilizing the FT beam profile with our established protocols in bone regeneration, as a therapeutic tool for future pre-clinical and clinical applications. Moreover, these studies have shown the mechanistic effects of the PBM light on intracellular pathway across the metabolic and differentiation of the osteoblasts towards bone regeneration.

碩士
國立交通大學
應用數學系數學建模與科學計算碩士班
102
In the case of singly connected graph, the computational complexity for calculating beliefs can be reduced by using the belief propagation. But in the case of loopy graph, it would cause some problem if we use the belief propagation to evaluate beliefs. There are some results for correcting those problems in the case of single loop, and those results were made by Weiss in [11]. In this paper, we use those results in [11] to solve another case, which has two single loops connected by a singly connected sub-graph. In the end, we attempt to apply Loopy belief propagation to an experiment of pose estimation in the face image. In this experiment, a face image can be composed by eyes, nose and mouth. Our purpose is to find the most likely pose of those parts in the face image. Those unknown poses of parts will be unobserved variables of a joint distribution, and the graph of this distribution has a loop. We then use belief propagation to compute the beliefs for this joint distribution so that we can find those poses and plot the locations on the face image.

碩士
大葉大學
電信工程學系碩士班
94
For recognizing the EM characteristics of mediums, the simulation is developed in this thesis. Using the simulated results of S parameters, the dielectric constant and loss tangent of medium can be calculated by EM formulas. Generally, the transmitting antennas in test ranges are consist of various narrow band antennas for wide band applications. The drawback are higher cost for purchasing the probe antennas, time consuming for changing and uncertainty of the antenna patterns; therefore, a novel transmitter antenna constructed with low directivity wideband horn and wideband balun will be developed in this thesis and applied for the Near-field antenna measurement system. The operating frequency from 1 GHz to 18 GHz, low directivity and symmetry antenna pattern are achieved. Meanwhile, a ultra-wideband bow-tie receiving antenna is designed and applied in the water from 3GHz to 12.5 GHz. Both S-parameters and radiation patterns are measured by the network analyzer and impulse time domain antenna measurement system respectively. The EM wave propagation for various media is analyzed

碩士
大同大學
光電工程研究所
92
In this thesis , we will discuss the variation by of the characteristics simulating the LiNbO3/Buffer/Si structures to gain the phase velocity and electromechanical coupling coefficient. LiNbO3 was used popularly in a lot kinds of cut and modulus, because there are many different phase velocity and electromechanical coupling coefficient combinations in different cut and modulus. So in this thesis , we will focus on the LiNbO3 thin film. By the references [4-55], we will select four different kinds of buffer layer materials which is AlN、ZnO for the piezoelectric materials and Al2O3、SiO2 for the non-piezoelectric materials to get the better characteristics for the growing high-quality LiNbO3 thin films. We will use the silicon substrate for the integration of SAW with the maturing Si-based semiconductor devices.

碩士
大同大學
資訊工程學系(所)
96
Artificial intelligence technology has been extensively used in various applications. It is also used as an auxiliary tool for medical policy decision making. The application of back-propagation network in this research builds the assortment model from the history of kidney transplant patients who took the cyclosporine. About 66.29% of patients can be correctly identified by doctor’s personal experience to differentiate the results from using cyclosporine, while 86.81% of correctness is achieved by the application of back-propagation neural network strategy. We hope the results could help the medical personnel master the effectiveness of cyclosporine and improve the drug safety, the quality of using medicine, and the survival rate of kidney transplant patients.

Inverse problems are very challenging as these problems involve, finding the cause by analyzing the effects. In structural dynamics problems, the effects are normally measured in terms of dynamic responses in structures. These responses which are used to find the cause generally have partial data, embedded with measurement noise, and are truncated. Due to these problems, inverse problems are generally ill-posed in most cases as against forward problems. In this dissertation, we solve five different types of inverse problems involving high-frequency transient loads. All these problems are solved using the time-domain spectral element method (TSFEM) along with experimental or numerically simulated responses. The dissertation starts with the formulation of the forward problem, which is obtaining the responses from known input forces. The general formulation of TSFEM of composite Timoshenko beam is derived. The isotropic beam formulation is shown as a special case in this formulation. Five different inverse problems solved in the thesis are: 1. Force identification problem: A new algorithm is developed using a 1-D waveguide, involving an eight noded spectral finite element. The force identification is carried out, using a few measured responses on the structure, and using TSFEM we reconstruct the input force. This is followed by a portal frame example to demonstrate the wave reflection complexities. New procedures are developed to use various types of response data like displacement, velocity, acceleration, and strain to identify the force. 2. Material identification problem: A new procedure making use of the developed TSFEM, few responses, and nonlinear least square techniques are used to determine the material properties. Also, we show the case, in which we derive the material properties without force input consideration. 3. Crack location detection problem: A new procedure is developed using TSFEM and mechanics of crack. Three methods are described, in which the first method uses only responses and wave speeds to determine the location of the crack. In the second method, force reconstruction using the measured responses is carried out and this, in turn, is used to determine the location of the crack. The third method uses the residues of the actual force and the reconstructed forces using the healthy beam matrices and cracked beam responses. A new procedure to identify the crack location using a general force input pulse having many frequency components is also developed. 4. Material defect identification: Material defects like voids or density changes are identified using TSFEM. Location and magnitude of defect are identified using response computation and using the method of residues. 5. Porous location and identification in a composite material: TSFEM is used to construct a porous element and this is used along with a healthy beam to generate the responses. A force reconstruction algorithm is used to identify the location of the porous element. The Force residue method to identify the location of the defect is also demonstrated. Further, we make use of the material identification algorithm with a few modifications to evaluate all the parameters for the porous element.

The specialized myocytes of the ventricular conduction system (VCS) coordinate ventricular contraction and are critical for efficient pumping by the heart. Impaired VCS conduction is characteristic of inherited forms of cardiac conduction disorders. Here we show that the Iroquois homeobox 3 (Irx3) transcription factor is preferentially expressed in the developing and mature VCS. Loss of Irx3 in mice results in slowed VCS conduction and prolonged QRS duration with right bundle branch block, caused by reduction (42%) in VCS-specific connexin 40 (Cx40) expression and VCS fiber hypoplasia, absent in littermate controls. Therefore, we show that the role of Irx3 in the heart is two-fold, whereby Irx3 (1) indirectly regulates Cx40 gene expression, by repressing a repressor of Cx40 transcript, and (2) controls VCS maturation, possibly in an Nkx2-5-dependent manner. To our knowledge, this is the first report of a role for Irx3 in regulating the development and function of the VCS.