yes / The main purpose of this paper is to assess moment redistribution in continuous concrete beams reinforced with fibre reinforced polymer (FRP) bars. A numerical technique based on equilibrium of forces and full compatibility of strains has been developed to evaluate the moment–curvature relationships and moment capacities of FRP and steel reinforced concrete sections. Moment redistribution has then been assessed by comparing elastic and experimental moments at failure, and moment capacity at critical sections of continuous FRP reinforced concrete beams reported on the literature. The curvature of under reinforced FRP sections was large at FRP rupture but failure was sudden, that would not allow any moment redistribution. On the other hand, FRP over reinforced sections experienced higher curvature at failure than steel over reinforced sections owing to the lower FRP modulus of elasticity. Although the experimental and elastic bending moment distributions at failure are significantly different for many beams tested elsewhere, in particular CFRP reinforced concrete beams, the experimental bending moment over the middle support at failure was far lower than the corresponding moment capacity owing to the de-bonding of FRP bars from concrete in the middle support region. Furthermore, the hogging moment redistribution over the middle support is always larger than that at mid-span by around 66%. It was also shown that the load capacity prediction of continuous FRP reinforced concrete beams using the de-bonding moment at the middle support section was the closest to the experimental failure load.

The "Knuckle-walking Hominin Hypothesis" postulates that there was a knuckle-walking phase during the transition from quadrupedalism to bipedalism. To address this question, previous research has focused on the search for a "signal" within the wrist, and metacarpals of extant knuckle walkers that can be used to infer this locomotor pattern in extinct hominins. To date, the examined features have not yielded a clear, non-contested signal. I explore the Knuckle-walking Hominin Hypothesis in two ways: 1. by examining the hand postures and the manual pressure application of Pan and Gorilla during knuckle walking to determine whether there are species specific differences and 2. by examining the internal and external morphology of the manual phalanges in an attempt to isolate a clear "knuckle-walking signal". Chimpanzees are more variable in their preferred contact digits, and use both hand positions with equal frequency ("palm-in" - palm facing toward the body and "palm-back" - palm facing posteriorly). In contrast, gorillas consistently make contact with all four digits 2-5, maintain a pronated arm, and use the palm-back hand position. In both taxa, hand position affects which digit acts as the final touch-off element and therefore receives maximum pressure in a given step, and digit 5 receives significantly less pressure than the other rays. Gorillas are, in effect, practicing a refined subset of the variety of knuckle-walking postures used by the more arboreal chimpanzees. A clear knuckle-walking signal is seen in both the external and internal morphology of the phalanges. Chimpanzees and gorillas have the same middle phalangeal curvature profile with the greatest curvature found in digit 5 (5 > 2 > 3 > 4), the element that receives the least amount of pressure. This phalangeal curvature profile is a feature not shared with any of the included taxa practicing different modes of locomotion. They also have similar Indices of Relative Curvature (IRC-middle phalangeal curvature/proximal phalangeal curvature) for digits 2-5 that clearly delineate them with "flatter" middle phalanges and more curved proximal phalanges (IRCs = ~0.85), from quadrupeds with more curved middle than proximal phalanges (IRCs > 1), and suspensory primates with higher and more equal curvature values for both elements (IRCs = ~1). This ability to differentiate between locomotor groups holds if the IRCs are composed of elements from different rays of the same manus and from elements of different individuals. Within the trabecular bone structure, knuckle walkers are differentiated from quadrupeds and suspsensory primates in 3 locations: the metacarpal head, and the proximal ends of the middle and proximal phalanges. In particular, the metacarpal head shows distinct differences between the groups: knuckle walkers have a palmar-dorsal alignment of trabeculae and disc-like shape, suspensory taxa have a proximodistal alignment and rod-like shape and quadrupeds have a proximodistal alignment and disc-like shape. The ability to differentiate between locomotor categories using isolated zones increases the applicability of these signals to a fragmentary and limited fossil record. The morphological similarities, specifically the shared curvature profile, and the similar knuckle-walking kinematics employed by chimpanzees and gorillas point to a shared origin of knuckle walking.

The purpose of this research was to enhance the methods towards the development of an efficient three dimensional face recognition system. More specifically, one of our aims was to investigate how the use of curvature of the diagonal profiles, extracted from 3D facial geometry models can help the neutral face recognition processes. Another aim was to use a gender classifier employed on 3D facial geometry in order to reduce the search space of the database on which facial recognition is performed. 3D facial geometry with facial expression possesses considerable challenges when it comes face recognition as identified by the communities involved in face recognition research. Thus, one aim of this study was to investigate the effects of the curvature-based method in face recognition under expression variations. Another aim was to develop techniques that can discriminate both expression-sensitive and expression-insensitive regions for ii face recognition based on non-neutral face geometry models. In the case of neutral face recognition, we developed a gender classification method using support vector machines based on the measurements of area and volume of selected regions of the face. This method reduced the search range of a database initially for a given image and hence reduces the computational time. Subsequently, in the characterisation of the face images, a minimum feature set of diagonal profiles, which we call T shape profiles, containing diacritic information were determined and extracted to characterise face models. We then used a method based on computing curvatures of selected facial regions to describe this feature set. In addition to the neutral face recognition, to solve the problem arising from data with facial expressions, initially, the curvature-based T shape profiles were employed and investigated for this purpose. For this purpose, the feature sets of the expression-invariant and expression-variant regions were determined respectively and described by geodesic distances and Euclidean distances. By using regression models the correlations between expressions and neutral feature sets were identified. This enabled us to discriminate expression-variant features and there was a gain in face recognition rate. The results of the study have indicated that our proposed curvature-based recognition, 3D gender classification of facial geometry and analysis of facial expressions, was capable of undertaking face recognition using a minimum set of features improving efficiency and computation.

Pages vi, 34, 68, 158, 208 and 226 are blank and therefore omitted. / <p> To assess the ductility of shear walls under earthquake loading, more experimental evidence is strongly needed. Ductile response can be achieved through the development of a flexural plastic hinge at the base characterized by yielding of the vertical reinforcement. The length of the plastic hinge and the ultimate curvatures within this region are the essential parameters affecting the ductility and ultimate displacements of reinforced masonry shear walls. The discrepancies in existing information regarding the length of plastic hinges and ultimate curvature may be attributed to the effects of many shear wall parameters such as distribution and amount of vertical and horizontal steel, level of axial load, and wall aspect ratio. </p> <p> The focus of this study was to evaluate the effect of different parameters on plastic hinge length, energy dissipation, and on general ductility of masonry shear walls. To address the aforementioned goal, six fully grouted reinforced masonry walls were tested under fully reversed cyclic lateral loading. All walls were designed to experience ductile flexural failure. The test matrix was chosen to investigate the effects of the amount and distribution of vertical reinforcement and the level of applied axial load on the lateral loading response and ductility of reinforced masonry shear walls. To examine the effects of these parameters, measurements of the applied loads, vertical and horizontal displacements as well as strains in the reinforcing bars were used to analyze the behaviour of the walls. Also, from these measurements, other quantities used in analysis were determined, including displacement ductilities, curvature profiles, energy dissipation and equivalent plastic hinge length. </p> <p> The results show high ductile capability in the plastic hinge region and very little degradation of strength for cyclic loading. High levels of energy dissipation in the reinforced concrete masonry shear walls were achieved by flexural yielding of the vertical reinforcement. All walls showed increasing hysteretic damping ratios with increase in displacement. Results showed that displacement ductility and energy dissipation were highly sensitive to increases in amount of vertical reinforcement but were less dependent on the level of applied axial stress. The results of this study also showed that the measured plastic zone length decreases with increase of the amount of reinforcement while it is almost the same for the different levels of axial stress. Based on the test results, it was shown that reinforced concrete masonry shear walls may be utilized in high intensity seismic areas with performance meeting or exceeding current expectations. </p> / Thesis / Master of Applied Science (MASc)

<p> A research programme is presented for assessing the capability of Hollow Structural Sections in Plastic Design. This investigation attempts to relate the flange slenderness and yield stress to the rotation capacity of Hollow Structural Sections subjected to both constant moment regions and to moment gradients. </p> <p> An experimental programme was performed on 31 different cross sections to evaluate the moment-curvature relationship which is of fundamental importance in Plastic Methods. The occurrence of local buckling for some sections in the compression flange and the consequent reduction in moment resistance is the critical factor which separates members into compact and non compact categories. </p> <p> The moment-curvature relations from tests are compared with analytical predictions. The plastic hinge rotations delivered by the present test sections are compared with the maximum practical requirements for plastically designed continuous beams. Theoretical elastic and inelastic buckling solutions of plate elements are also presented to relate to possible local buckling of the flats of square and rectangular hollow structural sections. </p> <p> Plate ratios of compression flanges are then selected for use in plastic design of hollow structural sections. Such a separation permits segregation into compact and non compact categories and can be used in working stress or elastic design methods. </p> / Thesis / Master of Engineering (ME)

In absence of external fields, vibrational modes of periodic systems are usually considered as linearly polarized and, as such, they do not carry angular momentum. Our work proves that non-adiabatic effects due to the electron-phonon coupling are time-reversal symmetry breaking interactions for the vibrational field in systems with non-collinear magnetism and large spin-orbit coupling. Since in these systems the deformation potential matrix elements are necessarily complex, a nonzero synthetic gauge field (Berry curvature) arises in the dynamic equations of the ionic motion. As a result, phonon modes are elliptically polarized in the non-adiabatic framework and intrinsic vibrational angular momenta occur even for non-degenerate modes and without external probes. These results are validated by performing fully relativistic ab-initio calculations on two insulating platinum clusters and a metallic manganese compound, with non-collinear magnetism. In both cases, non-adiabatic vibrational modes carry sizeable angular momenta comparable to the orbital electronic ones in itinerant ferromagnets.

This thesis aims to theoretically explore the geometrical effects on spin waves, the fundamental low-energy excitations of ferromagnets, propagating in curved magnetic shells. Supported by an efficient numerical technique developed for this thesis, several aspects of curvilinear spin-wave dynamics involving magnetic pseudo-charges, the topology of curved magnets, symmetry-breaking effects, and dynamics of spin textures are studied. In recent years, geometrical and curvature effects on mesoscale ferromagnets have attracted the attention of fundamental and applied research. Exciting curvature-induced phenomena include chiral symmetry breaking, the stabilization of magnetic skyrmions on Gaussian bumps, or topologically induced domain walls in Möbius ribbons. Spin waves in vortex-state magnetic nanotubes exhibit a curvature-induced dispersion asymmetry due to geometric contributions to the magnetic volume pseudo-charges. However, previous theoretical studies were limited to simple and thin curved shells due to the complexity of analytical models and the time-consuming nature of existing numerical techniques. For a systematic study of spin-wave propagation in curved shells, the first of five thematic parts of this thesis deals with developing a numerical method to calculate spin-wave spectra in waveguides with arbitrarily shaped cross-sections efficiently. For this, a finite-element/boundary-element method to calculate dynamic dipolar fields, the Fredkin-Koehler method, was extended for propagating waves. The technique is implemented in the micromagnetic modeling package TetraX developed and made available as open source to the scientific community. Equipped with this method, the second part of the thesis studies the influence of geometric contributions to the magnetic charges leading to nonlocal chiral symmetry breaking. Introducing the toroidal moment to spin-wave dynamics allows us to predict whether this symmetry breaking is present even in complicated systems with spatially inhomogeneous equilibria or shells with gradient curvatures. The theoretical study of curvilinear magnetism is extended to thick shells, uncovering a curvature-induced nonreciprocity in the spatial mode profiles of the spin waves. Consequently, nonreciprocal dipole-dipole hybridization between different modes leads to asymmetric level gaps enabling spin-wave diode behavior. Besides unidirectional transport, curvature modifies the weakly nonlinear spin-wave interactions. The third part of this thesis focuses on topological effects. A topological Berry phase of spin waves in helical-state nanotubes is studied and connected to a local curvature-induced chiral interaction of exchange origin. The topology of more complicated systems, such as magnetic Möbius ribbons, is shown to impose selection rules on the spectrum of possible spin waves and split it into modes with half and full-integer indices. To understand the effects of achiral symmetry breaking, the fourth part of this thesis focuses on the deformation of symmetric shells, here, cylindrical nanotubes, to polygonal and elliptical shapes. Lowering rotational symmetry leads to splitting spin-wave dispersions into singlet and doublets branches, which is explained using a simple group theory approach and is analogous to the electron band structure in crystals. Apart from mode splitting, this symmetry breaking allows hybridization between different spin-wave modes and modifies their microwave absorption. While this hybridization appears discretely in polygonal tubes, tuning the eccentricity of elliptical tubes allows controlling the level gaps appearing from hybridization. Finally, the last part focuses on the dynamics of spin waves in the vicinity of spin textures in curvilinear systems. The dynamics of topological meron strings are shown to exhibit dipole-induced chiral symmetry breaking like spin waves in curved shells. Moreover, modulational instability is predicted from the softening of their gyrotropic modes, similar to the formation of stripe domains in flat systems. This stripe domain formation can also be observed in curved shells but leads to tilted or helix domains. Overall, this thesis contributes to the fundamental understanding of spin-wave dynamics on the mesoscale but also advertises these for possible magnonic applications.:Abstract Acknowledgements Contents 1 Introduction Theoretical Foundations 2 Micromagnetic continuum theory 3 Spin waves Numerical methods in micromagnetism 4 Overview 5 Finite-element dynamic-matrix method for propagating spin waves 6 Numerical reverse-engineering of spin-wave dispersions 7 TetraX: A micromagnetic modeling package Aspects of curvilinear magnetization dynamics 8 Magnetic charges 9 Topology 10 Achiral symmetry breaking 11 Spin textures Closing remarks 12 Summary and outlook 13 Publications and conference contributions Appendix A Extended derivations and proofs B Supplementary data and discussion List of Figures List of Tables Bibliography Alphabetical Index / Ziel dieser Arbeit ist es, die geometrischen Effekte auf Spinwellen (Magnonen), die fundamentalen niederenergetischen Anregungen von Ferromagneten, die sich in gekrümmten magnetischen Schalen ausbreiten, theoretisch zu untersuchen. Unterstützt durch ein effizientes numerisches Verfahren, das für diese Arbeit entwickelt wurde, werden verschiedene Aspekte der krummlinigen Spinwellen-Dynamik untersucht: magnetische Pseudoladungen, die Topologie gekrümmter Magnete, Symmetriebrechungseffekte und die Dynamik von Spin-Texturen. In den letzten Jahren haben Geometrie- und Krümmungseffekte auf mesoskaligen Ferromagneten die Aufmerksamkeit der Grundlagen- und angewandten Forschung auf sich gezogen. Zu den spannenden krümmungsinduzierten Phänomenen gehören chirale Symmetriebrechung, die Stabilisierung magnetischer Skyrmionen auf Gaußschen Unebenheiten oder topologisch induzierte Domänenwände in Möbiusbändern. Spinwellen in magnetischen Nanoröhren im Vortex-Zustand zeigen eine krümmungsinduzierte Dispersionsasymmetrie aufgrund geometrischer Beiträge zu den magnetischen Volumen-Pseudoladungen. Bisherige theoretische Studien beschränkten sich jedoch auf einfache und dünne gekrümmte Schalen, da die analytischen Modelle zu komplex und die bestehenden numerischen Verfahren zu zeitaufwändig waren. Für eine systematische Untersuchung der Spinwellenausbreitung in gekrümmten Schalen befasst sich der erste von fünf thematischen Teilen dieser Arbeit mit der Entwicklung einer numerischen Methode zur effizienten Berechnung von Spinwellenspektren in Wellenleitern mit beliebig geformten Querschnitten. Dazu wurde eine Finite-Elemente/Grenzelement-Methode zur Berechnung dynamischer Dipolfelder, die Fredkin-Köhler-Methode, für propagierende Wellen erweitert. Die Technik ist in dem mikromagnetischen Modellierungspaket TetraX implementiert, das während dieser Arbeit entwickelt und der wissenschaftlichen Gemeinschaft als Open Source zur Verfügung gestellt wurde. Ausgestattet mit dieser Methode untersucht der zweite Teil der Arbeit den Einfluss von geometrischen Beiträgen zu den magnetischen Ladungen, die zu nichtlokaler chiraler Symmetriebrechung führen. Durch die Einführung des toroidalen Moments in die Spin-Wellen-Dynamik lässt sich vorhersagen, ob diese Symmetriebrechung auch in komplizierten Systemen mit räumlich inhomogenen Gleichgewichtszuständen oder magnetischen Schalen mit Gradientenkrümmungen vorhanden ist. Die theoretische Untersuchung des krummlinigen Magnetismus wird auf dicke Schalen ausgedehnt, für die eine krümmungsbedingte Nichtreziprozität in den räumlichen Modenprofilen der Spinwellen gefunden wird. Als Konsequenz führt nicht-reziproke Dipol-Dipol-Hybridisierung zwischen verschiedenen Moden zu asymmetrischen Niveaulücken, die die Konstruktion von Spinwellen-Dioden ermöglichen. Neben unidirektionalem Transport modifiziert die Krümmung auch die schwach nichtlinearen Spin-Wellen-Wechselwirkungen. Der dritte Teil dieser Arbeit befasst sich mit topologischen Effekten. So wird eine topologische Berry-Phase von Spinwellen in Nanoröhren im Helix-Zustand untersucht, die mit einer lokalen krümmungsinduzierten chiralen Wechselwirkung in Verbindung gebracht wird. Es wird gezeigt, dass die Topologie komplizierterer Systeme, wie z.B. magnetischer Möbiusbänder, dem Spektrum möglicher Spinwellen Auswahlsregeln auferlegt, das damit in Moden mit halb- und ganzzahligen Indizes aufspaltet. Um die Auswirkungen der achiralen Symmetriebrechung zu verstehen, konzentriert sich der vierte Teil dieser Arbeit auf die Verformung symmetrischer Schalen, hier zylindrischer Nanoröhren, zu polygonalen und elliptischen Formen. Die Verringerung der Rotationssymmetrie führt zu einer Aufspaltung der Spin-Wellen-Dispersionen in Singlets Dublets, was mit einem einfachen gruppentheoretischen Ansatz erklärt wird und analog zur Elektronenbandstruktur in Kristallen ist. Abgesehen von der Modenaufspaltung ermöglicht diese Symmetriebrechung eine Hybridisierung zwischen verschiedenen Spin-Wellen-Moden und verändert zudem deren Mikrowellenabsorption. Während diese Hybridisierung in polygonalen Röhren diskret auftritt, kann die Exzentrizität elliptischer Röhren genutzt werden um die durch Hybridisierung entstehenden Niveaulücken kontinuierlich einzustellen. Schließlich konzentriert sich der letzte Teil auf die Dynamik von Spinwellen in der Umgebung von Spinstrukturen in krummlinigen Systemen. Es wird gezeigt, dass die Dynamik topologischer Meron-Strings dipol-induzierte chirale Symmetriebrechungen wie Spinwellen in gekrümmten Schalen aufweist. Darüber hinaus wird eine Instabilität der gyrotropen Mode vorhergesagt, ähnlich der Bildung von Streifendomänen in flachen Systemen. Diese Bildung von Streifendomänen kann auch in gekrümmten Schalen beobachtet werden, führt aber zu gekippten oder spiralförmigen Domänen. Insgesamt trägt diese Arbeit zum grundlegenden Verständnis der Spinnwellen-Dynamik auf der Mesoskala bei, aber diskutiert auch mögliche magnonische Anwendungen.:Abstract Acknowledgements Contents 1 Introduction Theoretical Foundations 2 Micromagnetic continuum theory 3 Spin waves Numerical methods in micromagnetism 4 Overview 5 Finite-element dynamic-matrix method for propagating spin waves 6 Numerical reverse-engineering of spin-wave dispersions 7 TetraX: A micromagnetic modeling package Aspects of curvilinear magnetization dynamics 8 Magnetic charges 9 Topology 10 Achiral symmetry breaking 11 Spin textures Closing remarks 12 Summary and outlook 13 Publications and conference contributions Appendix A Extended derivations and proofs B Supplementary data and discussion List of Figures List of Tables Bibliography Alphabetical Index

The goal of this thesis is to identify differences and consistencies in the trajectories taken by foraging agents before and after they have learned the location of a target. The challenge is that these agents do not go directly towards the target after learning and keep a certain amount of randomness in their paths. We use different versions of discrete curvature and head angle as tools in this analysis. We also build models of foraging agents using stochastic processes with data supported parameters.

No description available.

No description available.