This work includes brief overview of the theory behind two-dimentional languages which was the main theme examined in previous work. Based upon this theory there are next chapters introducing a new concept of three-dimentional and multi-dimentional languages. For each type of language there is a definition of corresponding type of strings and string operations. Finally, for each type of language there are definitions of developed formal gramatics and automata. Along with theory, in work there is an demonstration of developed program, which provides simulation of introduced multidimensional automata.

Στην μεταπτυχιακή εργασία ειδίκευσης περιγράφεται η σύνθεση και ο χαρακτηρισμός νέων υβριδικών ανόργανων-οργανικών χαμηλοδιάστατων ημιαγωγών βασισμένων σε αλογονίδια του μολύβδου και διαφόρων χαλκογενιδίων μετάλλων για οπτικές και οπτικοηλεκτρονικές εφαρμογές. Για να γίνουν κατανοητές οι σχετικές έννοιες των χαμηλοδιάστατων ημιαγωγών αρχικά αναφερόμαστε στην κρυσταλλική δομή των στερεών, τη σχετική θεωρία των ενεργειακών ζωνών και ειδικότερα στους ημιαγωγούς. Με βάση αυτά αναπτύσσεται η θεωρία για τα χαμηλοδιάστατα ημιαγώγιμα συστήματα και ερμηνεύονται τα σχετικά κβαντικά φαινόμενα. Ειδικότερα, εξηγείται πως οι ιδιότητες που υπάρχουν στους τρισδιάστατους ημιαγωγούς αλλάζουν όταν το μέγεθος αυτών τροποποιηθεί και αποκτήσουν κάποια από τις τρεις διαστάσεις στην κλίμακα του νανομέτρου. Γίνεται αναφορά στους διάφορους τρόπους σύνθεσης νέων χαμηλοδιάστατων συστημάτων, στη μορφολογία τους καθώς και στις ιδιότητες και μεθόδους χαρακτηρισμού με έμφαση στις οπτικές και ηλεκτρονικές ιδιότητές τους. Τέλος, δίνονται πρώτα αποτελέσματα διαφόρων χαμηλοδιάστατων ημιαγώγιμων συστημάτων μαζί με τη φασματοσκοπική και ηλεκτρική ανάλυση τους. Επίσης, αναλύονται οι ιδιότητες τους σε σχέση με απλά μοντέλα και συζητείται η εφαρμογή των συγκεκριμένων σε πιθανές εφαρμογές με βάση τις οπτικές ιδιότητες τους. / In this master thesis it is described the synthesis and the characterization of hybrid inorganic - organic low dimensional semiconductors based on lead halides and various metal chalcogenides for optical and optoelectronics applications. In order to become more comprehensive, the relative notions of low dimensional semiconductors, we initially report on the theory of energy bands for crystalline solids and more specifically for semiconductors. In such a context, the theory for the low dimensional semiconductor systems is presented and is interpreted in terms of the quantum theory. More specifically, we explain that properties that exist in the three-dimensional semiconductors change when these formed in such a way that one of their dimensions are in the nanometric scale. Also, report is being given in the various methods of synthesis of new low dimensional systems, in their morphology as well as in the attributes and methods of characterization with emphasis in the optical and electronic attributes. Finally, first results of new low dimensional semiconductors systems are presented along with their optical and electric characterization. Also, their attributes are analyzed concerning simple models as well as their application is discussed in possible applications with basis their optical attributes.

<p> Two-dimensional C-H chemical shift correlation spectroscopy provides a large amount of information in a two dimensional matrix. Many variations of these experiments have been in an effort to enhance the information content of these experiments. Decoupling of multiplet signals is one method used to increase the sensitivity of an NMR experiment. Simple broadband decoupling in ω2 is done by irradiating the correlated channel during acquisition. Decoupling in ω1 must be done using less direct methods, one of which is to use bilinear rotation decoupling. The traditional description of the effect that a BIRD pulse has on the spin systems is based on a simple AX system which is at equilibrium at the beginning of the pulse, which does not apply in many real systems.</p> <p> This study uses the Superspin formalism to show in more detail the behaviour of more complex spin systems during the BIRD sequence, and the effect of varying parameters within the BIRD sequence. This treatment involved the derivation of complete spherical tensor descriptions of AX, AX2, and AX3 spin systems. This allowed the derivation of a mathematical description of an INEPT style pulse sequence, where the refocussing pulse in INEPT was replaced with the BIRD sequence. The derivation of the general evolution transformations of the spherical tensors in Liouville space also allowed the theoretical treatment to be done in a single basis, where earlier implementations of the Superspin formalism converted between a spherical tensor basis for the treatment of pulses and a Hamiltonian basis for the treatment of delays. This theoretical treatment allows the derivation of a functional form for the dependence of the carbon signal intensity on the variation of the interpulse delay in the BIRD sequence.</p> <p> This formalism was also used to analyze the occurrence of artifacts in two dimensional heteronuclear shift correlation spectra, due to strong coupling between methylene protons. These artifacts were studied in experiments that attempt broadband homonuclear decoupling in ω1 through the use of constant evolution time between the initial excitation pulse and polarization transfer. Two experiments were analyzed, the COLOC experiment and the HETRES experiment. The superspin formalism was used to deduce a functional form for the intensity of the artifact as a function of the strength of the coupling between the methylene protons.</p> / Thesis / Master of Science (MSc)

<p>This thesis focuses on the fluctuation in the switching current $I_s$ of superconducting Al nanowires. We discovered that the maximum current which nanowires can support is limited by a single phase slip at low temperature. </p><p>Al superconducting nanowires less than 10 nm wide were fabricated based on a MBE grown InP ridge template in an edge-on geometry. The method utilizes a special substrate featuring a high standing 8nm-wide InP ridge. A thin layer of Al was evaporated on the substrate and Al on the ridge formed nanowires.</p><p>The fluctuation effects starts to dominate in the nanowire due to reduced energy barrier. One of such effects is the phase slip. The phase slip is a topological event, during which the superconducting phase between two superconducting electrodes changes by $2\pi$. The phase slip broadens the normal-superconducting transition. Part of the nanowire becomes normal during the phase slip and forms a normal core. The normal core generates heat and causes the premature switching in superconducting nanowires.</p><p></p><p>The nanowire becomes superconducting below the critical temperature $T_c$. The superconducting-normal transition was studied in the thesis. The transition of nanowires with superconducting leads qualitatively fits the thermally activated phase slip (TAPS) theory. On the other hand, the transition of the nanowires with normal leads showed a resistive tail due to the inverse-proximity effect.</p><p>The nanowire switches from the superconducting state to the normal state as the current is increased. Ideally, the maximum current is set by a pair-breaking mechanism, by which the kinetic energy of quasi-particles exceeds the bonding energy of Cooper pairs. This is called the critical current, $I_c$. In practice, the measured maximum current, called the switching current $I_s$, cannot reach $I_c$ because of the phase slip.</p><p>$I_s$ shows stochasticity due to the phase slip. For the nanowires with superconducting leads, the average $I_s$ approximately follows but falls below $I_c$. The fluctuation in $I_s$ shows non-monotonic behavior, in contrast to other studies. The fluctuation first increases and then decreases rapidly with increasing temperature. The fluctuation behavior is consistent with a scenario where the switch is triggered by a single phase slip at low temperature while by multiple phase slips at higher temperature. Thermal activation of phase slips appears dominant at most temperatures. However, in the thinnest nanowire, the saturation of the fluctuation at low temperature indicates that the phase slips by macroscopic quantum tunneling.</p><p>The superconducting nanowires with normal leads were also studied. One of the distinctive properties of our nanowire (the critical field of 1D nanowire is 10 times larger than that of a 2D superconducting film) allowed us to study the same nanowire with different leads (superconducting or normal). Both the average $I_s$ and the fluctuation in $I_s$ differed qualitatively depending on whether the leads were superconducting or normal. The temperature dependence of the average $I_s$ followed the $I_c$ of the Josephson junction instead of the phenomenological pair-breaking $I_c$. The difference was found to depend on both the temperature (close to $T_c$ or 0) and the length (shorter or longer than the charge imbalance length). Our study also showed that nonlinear current-voltage (IV) curves were observed due to the inverse-proximity effect.</p> / Dissertation

A family of concave penalties, including the smoothly clipped absolute deviation (SCAD) and minimax concave penalties (MCP), has been shown to have attractive properties in variable selection. The computation of concave penalized solutions, however, is a difficult task. We propose a majorization minimization by coordinate descent (MMCD) algorithm to compute the solutions of concave penalized generalized linear models (GLM). In contrast to the existing algorithms that uses local quadratic or local linear approximation of the penalty, the MMCD majorizes the negative log-likelihood by a quadratic loss, but does not use any approximation to the penalty. This strategy avoids the computation of scaling factors in iterative steps, hence improves the efficiency of coordinate descent. Under certain regularity conditions, we establish the theoretical convergence property of the MMCD algorithm. We implement this algorithm in a penalized logistic regression model using the SCAD and MCP penalties. Simulation studies and a data example demonstrate that the MMCD works sufficiently fast for the penalized logistic regression in high-dimensional settings where the number of covariates is much larger than the sample size. Grouping structure among predictors exists in many regression applications. We first propose an l2 grouped concave penalty to incorporate such group information in a regression model. The l2 grouped concave penalty performs group selection and includes group Lasso as a special case. An efficient algorithm is developed and its theoretical convergence property is established under certain regularity conditions. The group selection property of the l2 grouped concave penalty is desirable in some applications; while in other applications selection at both group and individual levels is needed. Hence, we propose an l1 grouped concave penalty for variable selection at both individual and group levels. An efficient algorithm is also developed for the l1 grouped concave penalty. Simulation studies are performed to evaluate the finite-sample performance of the two grouped concave selection methods. The new grouped penalties are also used in analyzing two motivation datasets. The results from both the simulation and real data analyses demonstrate certain benefits of using grouped penalties. Therefore, the proposed concave group penalties are valuable alternatives to the standard concave penalties.

Indiana University-Purdue University Indianapolis (IUPUI) / The luting agent is a crucial factor in the outcome of cemented fixed restorations. A new water-based cement, Ceramir C&B (CM), approved to be marketed in the US, is composed of calcium aluminate and glass ionomer. CM is a luting agent indicated for permanent cementation of cast restorations, all-zirconia or all-alumina crowns, and prefabricated metal and cast dowel and cores. The manufacturer claims that the cement has demonstrated favorable biocompatibility properties when tested in vitro and in vivo and has proven to be bioactive. The objective of this study was to evaluate volumetric dimensional changes and the amount of Ca2+ released by the new luting agent. Twenty specimens of each material, namely calcium aluminate glass ionomer, resin-modified glass ionomer, and two resin luting agents, were fabricated and weighed. The 20 specimens for all materials were divided into four groups (five samples in each group) based on storage conditions: silicone oil at 22°C and 37°C and distilled water at 22°C and 37°C. Using the manufacturers’ instructions for each material, cylindrical specimens were prepared with dimensions of 7 +0.1 mm in diameter and 2 +0.1 mm in height. A 0.01-mg resolution balance was used to determine volumetric dimensional change using an Archimedean equation. Measurements were made 30 minutes after mixing, and at the time intervals of 7 days, 14 days, 21 days, and 30 days, and after total dehydration of the specimen. Chemical analyses of the solutions were performed using atomic absorption spectroscopy to determine the Ca+2 ion concentration. Moreover, the pH values were measured to determine the OH–concentration in the solutions. The results showed that CM had the most expansion among the tested luting agents in distilled water at 22°C and 37°C, and significantly increased at higher temperature. In silicone oil, resin-modified glass ionomer shrank the most and also shrank more with the high temperature. The result of the ion concentration analysis indicated that Ca+2 and OHion release increased with increasing time and also significantly with temperature rise. In conclusion, calcium aluminate-glass ionomer exhibited the most significant dimensional change when stored in water storage. The solubility of the tested luting agents should be evaluated in the future because they were not evaluated in this study. Furthermore, to evaluate the clinical effect of the dimensional changes, the impact on the gap formation at tooth-crown margins should be determined in future work.

Design techniques for heterogeneous three-dimensional (3-D) integrated circuits are developed in this thesis. Heterogeneous 3-D integration is a platform for multifunctional, high performance, and low power electronics. For the advancement of heterogeneous 3-D ICs, contactless solutions are investigated to implement inter-tier communication between tiers manufactured with disparate processes and heterogeneous technologies. Two challenges for the development of contactless inter-tier communication are addressed, the design of energy efficient, heterogeneous inductive link transceivers and the impact of crosstalk noise due to the on-chip spiral inductors. Inter-tier communication between circuits fabricated with disparate technologies requires transceivers capable of operating at dissimilar voltages. A low power transceiver design methodology is proposed exploiting the difference in the core voltage between disparate manufacturing processes in a 3-D system in package. A transceiver is designed to provide inter-tier communication between a sensing layer, designed in a commercial 0.35 Âμm process and a processing layer, designed in an advanced 65 nm process. A significant gain in the power consumed by the transceiver is shown compared to equivalent state-of-the-art prototypes, profiting by the tradeoff between the core voltage and sensing ability of the transceiver circuit in each process. Due to their wireless nature, however the use of inductive links introduces crosstalk noise due to the coupling between the on-chip inductor and on-chip interconnects in the vicinity of the inductor. The noise caused by the inductor on the power distribution network of an integrated system is explored, analysed, and modelled through electromagnetic simulations. The spatial distribution of the noise is described for several power distribution topologies to determine the preferred placement solution for the power and ground network in the vicinity of the inductor, considering the impact on other sources of noise, such as the resistive drop. Depending upon the power distribution network topology, the induced noise can be reduced up to 70% when the additional noise caused by the inductive link is considered by the routing algorithm. Additionally, a methodology utilising an analytic model is proposed for the evaluation of the crosstalk noise without resorting to electromagnetic simulations. A closed-form magnetostatic model is developed to assess the mutual inductance between the on-chip inductor and the power distribution network. Utilising the mutual inductance model, the crosstalk noise is evaluated with SPICE simulations. A signifcant benefit in speedup is achieved, up to four orders of magnitude for determining the mutual inductance and up to 4.7× for the assessment of the crosstalk noise. The accuracy of the model is within 10% of the electromagnetic simulation.

京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第22837号 / 人健博第79号 / 新制||人健||6(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 岡 昌吾, 教授 藤井 康友, 教授 萩原 正敏 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DGAM

No description available.

No / Both prominent feature points and geodesic distance are key factors for mesh segmentation. With these two factors, this paper proposes a graph cut based mesh segmentation method. The mesh is first preprocessed by Laplacian smoothing. According to the Gaussian curvature, candidate feature points are then selected by a predefined threshold. With DBSCAN (Density-Based Spatial Clustering of Application with Noise), the selected candidate points are separated into some clusters, and the points with the maximum curvature in every cluster are regarded as the final feature points. We label these feature points, and regard the faces in the mesh as nodes for graph cut. Our energy function is constructed by utilizing the ratio between the geodesic distance and the Euclidean distance of vertex pairs of the mesh. The final segmentation result is obtained by minimizing the energy function using graph cut. The proposed algorithm is pose-invariant and can robustly segment the mesh into different parts in line with the selected feature points.