Quadruped robots can traverse a multitude of terrains with greater ease when compared to wheeled robots. Traditional rigid quadruped robots possess severe limitations as they lack structural compliance. Most of the existing soft quadruped robots are tethered and are actuated using pneumatics, which is a low grade energy source and lacks viability for long endurance robots. The work in this thesis proposes the development of a continuum actuator driven quadruped robot which can provide compliance while being un-tethered and electro-mechanically driven. In this work, continuum actuators are developed using mostly 3D printed parts. Additionally, the closed loop control of continuum actuators for walking is developed. Linear Quadratic Regulator (LQR) and pole placement based methods for controller synthesis were evaluated and LQR was determined to be better when minimizing the actuator effort and deviation from set-point. These continuum actuators are composed together to form a quadruped. Gait analyses on the quadruped were conducted and legs of the quadruped were able to trace the gaits for walking and galloping. / Fyrfotarobotar kan lättare korsa en mängd olika terränger jämfört med hjulrobotar. Traditionella styva fyrfotarobotar har kraftiga begränsningar då de saknar strukturell följsamhet. De flesta befintliga mjuka fyrbenta robotar är kopplade till en eller flera kablar och drivs av pneumatik, vilket är en lågkvalitativ energikälla och lämpar sig inte för robotar med lång uthållighet. Arbetet i denna avhandling föreslår utvecklingen av en continuum ställdonsdriven fyrfotarobot, som ger följsamhet samtidigt som den ¨ar frånkopplad och elektromekaniskt driven. I detta arbete framställs continuum ställdon med mestadels 3D-printade delar. Dessutom utvecklas dessa ställdons slutna kontrolloop för gång. Linjärkvadratisk regulator (LQR) och metoder baserade på polplacering utvärderades för styrsyntes, och det fastställdes att LQR presterade bättre när man minimerar ställdonets ansträngning samt avvikelse från referensvärde. Continuum ställdon sammansattes för att bilda en fyrbent robot. Gånganalyser utfördes på roboten och dess ben kunde följa gång- och galopprörelser.

Dans ce mémoire, j’analyse les trois pièces composées dans le cadre de ma maîtrise en musique, option composition et création sonore, à l’Université de Montréal. J’y décris mon processus de création et j’y présente les enjeux au cœur de ma démarche, notamment en ce qui concerne le volet narratif de mes œuvres et les impacts polystylistiques de cette narrativité. J’explique notamment comment je réconcilie la pluralité des sources d’inspirations puisées selon les besoins narratifs avec un désire d’uniformité esthétique et de cohérence formelle au sein de mes œuvres. Celles-ci sont donc présentées en ordre chronologique et vont comme suit : 1 : La prison de glace. Cycle de quatre poèmes pour baryton et piano d’une durée d’environ 15 minutes. 2 : L’épinette noire. Pièce narrativement abstraite écrite pour quatuor à corde d’une durée d’environ 5 minutes. 3 : La Dame blanche. Ballet pour orchestre symphonique inspiré de la légende de La Dame blanche de la chute Montmorency d’une durée d’environ 55 minutes. / In this thesis, I analyze the three pieces composed as part of my master's degree in music, option composition and sound creation, at Université de Montréal. I describe my creative process and I present the challenges that I faced throughout, especially regarding the narrative side of my pieces and its polystylistics impacts. I especially explain how I reconcile the plurality of inspirations drawn accordingly to my narrative needs despite a desire for aesthetic uniformity and formal coherence within each piece. They are therefore presented in chronological order and go as follows: 1: La prison de glace. A 15 minutes cycle of four poems for baritone and piano 2: L’épinette noire. Narratively abstract piece written for string quartet of about 5 minutes. 3: La Dame blanche. A 55 minutes ballet for symphonic orchestra inspired by the La Dame blanche de la chute Montmorency legend, lasting about 55 minutes. Keywords: Polyscalar Continuum, narrativity, composition, polystylism, ballet, quartet, poem, music

Call number: LD2668 .T4 1985 K57 / Master of Science

Doctor of Philosophy / Department of Biology / Ari M. Jumpponen / Dark septate endophytes (DSE) are darkly pigmented microfungal ascomycetes commonly observed in the healthy plant roots. Studying the functional roles of DSE is challenging as fundamental information about their identity, nutritional requirements, host range or host preference are lacking. Objective 1: root colonizing fungi were isolated from Konza plants roots and DSE fungi were identified by testing Koch’s postulates using leek plants. Periconia macrospinosa and Microdochium sp., were identified as DSE as they produced microsclerotia and chlamydospores in the root cortex. Select DSE were tested for their enzymatic capabilities and ability to utilize nitrogen sources: fungi tested positive for amylase, cellulase, polyphenol oxidases and gelatinase. Periconia isolates utilized organic and inorganic nitrogen suggesting facultative biotrophic and saprotrophic habits. Objective 2: a Microdochium isolate and three Periconia isolates were screened on 16 plant species (six native grasses and forbs, four crops) in a resynthesis system to test host range. DSE colonized all plant species, albeit to varying degrees. Host biomass and nutritional levels to DSE colonization varied within and among host species confirming the broad host range. Based on % responsiveness to DSE colonization, a metric similar to ‘mycorrhizal dependency’, grasses responded positively, while forbs and crops responded negatively. To test this observed ‘host preference’ under natural conditions, Konza roots from seven grass and nine forb species were surveyed for DSE colonization. Grasses hosted 50% greater DSE than forbs, supporting the broad host range and host preference of DSE fungi. Objective 3: three conspecific Arabidopsis ecotypes, Col-0, Cvi-0 and Kin-1 were inoculated with 25 P. macrospinosa isolates in resynthesis system. The three ecotypes responded differently to inoculation: Col-0 and Cvi-0 responded negatively, while Kin-1 response was neutral. Despite the negative or neutral response, each ecotype responded positively to one or two isolates. The outcomes were along the mutualism-parasitism continuum precluding an unambiguous assignment to any particular life-style. This study shows that the outcomes along this continuum are dictated by host and fungal genotypes. However, the more important question about their function remains. Additional studies with Arabidopsis microarrays are likely to provide unique insights into the potential roles of DSE.

The main objective of this thesis is to obtain critical insight on the role of crystalline incompatibilities in strain and curvature, induced in presence of line defects i.e. dislocations and disclinations, on the energy and geometry of specific features of the local microstructure, and on the bulk mechanical response of nanocrystalline/ultra-fine grained materials. To that end, studies are performed at the (1) inter-atomic and fine scale, and (2) at the mesoscale. The modelling approach is based on the field dislocation and disclination mechanics theory of continuously representated dislocations and disclinations. New, thermodynamically rigorous, multi-scale elastic constitutive laws based on the couple stress theory are developed to capture the effect of strain and curvature incompatibilities on the Cauchy and couple stresses. A new meso-scale elasto-viscoplastic constitutive model of defect incompatibilities based on a fast Fourier transform technique is developed. The desired scale transitioning is achieved via novel phenomenological defect density transport equations and the newly developed elastic constitutive laws. At the fine scale, the model is applied to study energetic interactions between strain and curvature incompatibilities associated with grain boundaries and their influence on triple line energies. Results reveal that incompatible lattice strains have the most significant contribution to the energy. Incompatible lattice curvatures have negligible energetic contributions but are necessary to characterize the geometry of grain boundaries. Finally, both incompatible lattice strains and curvatures are necessary to capture the structure sensitive mechanical behavior of grain boundaries. At the mesoscale, deformation of nanocrystalline aggregates characterized by residual curvatures is studied to identify the impact of the latter's presence on the local and bulk mechanical response of the aggregate. Relaxation of local stresses generated from residual curvatures reproduces the effect of GB dislocation emission. Uniaxial tensile loading of nanocrystalline microstructures containing residual curvatures reveals a softening in the yield stress which could explain the breakdown in Hall-Petch law in the nanocrystalline regime. Next, the possibility of characterizing incompatibilities using X-ray or neutron diffraction techniques is tested. Results reveal that only strains and their gradients contribute to the broadening of diffraction peaks; curvatures and their gradients have no contribution. This study leads to the development of a new multi-scale averaged strain based Fourier technique for generating virtual diffraction peaks.

This thesis consists of two parts. The first part explores a 2-d edge dislocation model to demonstrate characteristics of Field Dislocation Mechanics (FDM) in modeling single and collective behavior of individual dislocations. The second work explores the possibility of modelling adiabatic shear bands propagation within the timespace averaged framework of Mesoscopic Field Dislocation Mechanics (MFDM). It is demonstrated that FDM reduces the study of a significant class of problems of discrete dislocation dynamics to questions of the modern theory of continuum plasticity. The explored questions include the existence of a Peierls stress in translationally-invariant media, dislocation annihilation, dislocation dissociation, finite-speed-of-propagation effects of elastic waves vis-a-vis dynamic dislocation fields, supersonic dislocation motion, and short-slip duration in rupture dynamics. A variety of dislocation pile-up problems are studied, primarily complementary to what can be dealt by existing classical pile-up models. In addition, the model suggests the possibility that the tip of a shear band can be modelled as a localized spatial gradient of elastic distortion with the dislocation density tensor in continuum dislocation mechanics; It is demonstrated that the localization can be moved by its theoretical driving force and forms a diffuse traveling band tip, thereby extending the thin layer of the deformation band. A 3-d, parallel finite element framework of MFDM is developed in a geometrically nonlinear context for the purpose of modelling shear bands. The numerical formulations and algorithm are presented in detail. Constitutive models appropriate for single crystal plasticity response and J2 plasticity with thermal softening are implemented.

The purpose of this thesis is the theoretical study of interference and correlation effects in multimode and continuum mode quantum systems. We are concerned with interference effects in multiport devices which in a sense are generalised Mach-Zehnder interferometers. It is shown how these multimode devices can be employed for the study of negative result and interaction free measurements. Interference and coherence effects are also studied in relation to the radiation fields generated by atoms through the process of spontaneous emission. Besides first order interference, higher order coherence effects are investigated with the aid of Glauber's photodetection theory and it is found that detectors that lie in spacelike regions may display nonclassical correlations under certain conditions. It is well known that the vanishing of field commutators between regions that cannot be connected by subluminal signals reflects the locality of quantum field theory. But is it possible that these spacelike regions exhibit correlations that violate Bell type inequalities? This is the main question and principal concern of the thesis and the answer is affirmative, nonclassical correlations between spacelike regions are indeed possible. A scheme of four detectors that lie in spacelike points was also studied. In this case we do not consider the radiation field but a free scalar field in vacuum state. Nevertheless the virtual quanta of this field may induce nonclassical correlations if the intervals between the detectors are spacelike but small enough. The fundamental reason for this fact is the nonvanishing of the Feynman propagator outside the light cone. Since this propagator is decaying expotentially with the distance it is demonstrated that for large spacelike intervals field correlations obey classical inequalities. We should also note that different inertial observers will agree on the violation or not of these inequalities since the results are manifestly Lorentz invariant.

It has become clear in recent years that the study of interacting/merging galaxies plays an important role in understanding important astrophysical phenomena. This thesis presents an observational study of interacting/merging galaxies at radio frequencies. The observations have been carried out at extremely high resolution using very long baseline interferometry. The observations described here include: (1) A study of the high velocity Hi absorption associated with the peculiar galaxy NGC 1275; (2) A study of the radio continuum and Hi absorption of the ULIRG IRAS 172080014; (3) A study of the radio continuum and Hi absorption of the LIRG NGC 7674. Some of the most prominent results of these observations include: Detection of several narrow Hi absorption features in the high velocity system associated with NGC 1275. These Hi absorption lines were observed toward the strong radio nucleus 3C 84. The results indicate the existence of several Hi clouds with velocity differences and widths similar to those seen in Galactic neutral hydrogen absorption and similar to some of the Hi absorption seen in the Large Magellanic Cloud. The discovery of an extreme nuclear starburst region in the advanced merger system IRAS 172080014. Our results suggest a star formation rate of 84 M yr-1, and a supernova rate of 4 yr-1. Hi absorption is detected in multiple components with optical depths ranging between 0.3 and 2.5, and velocity widths between 58 and 232 km s-1. The detection of complex jet structures in the inner 1 kpc region of the galaxy NGC 7674. At full resolution, several compact sources are observed with brightness temperatures on the order of 107 K. While it is possible that one of these compact structures could host an AGN, they could also be shock-like features formed by the interaction of the jet with compact interstellar clouds in the nuclear region of this galaxy. At least eight Hi absorption lines are detected toward some of the continuum emission regions in NGC 7674. If the widest Hi feature in our observations is rotationally broadened by a central supermassive black hole, the implied dynamical mass is about 107 M.

<p>The equivalent continuum approach uses equivalent propertiesof rock mass as the input data for a continuum analysis. Thisis a common modeling method used in the field of rock mechanicsand hydrogeology. However, there are still unresolvedquestions; how can the equivalent properties be determined andis the equivalent continuum approach suitable for modeling thediscontinuous fractured rock mass.</p><p>The purpose of this paper is to establish a methodology todetermine the equivalent hydraulic and mechanical properties offractured rock masses by explicit representations of stochasticfracture systems, to investigate the scale-dependency of theproperties, and to investigate the conditions for theapplication of the equivalent continuum approach for thefractured rock masses. Geological data used for this study arefrom the site characterization of Sellafield, Cumbria, UK. Aprogram for the generation of stochastic Discrete FractureNetwork (DFN) is developed for the realization of fractureinformation and ten parent DFN models are constructed based onthe location, trace length, orientation and density offractures. Square models with the sizes varying from 0.25 m× 0.25 m to 10 m × 10 m are cut from the center ofthe each parent network to be used for the scale dependencyinvestigation. A series of the models in a parent network arerotated in 30 degrees interval to be used for investigation oftensor characteristic. The twodimensional distinct elementprogram, UDEC, was used to calculate the equivalentpermeability and compliance tensors based on generalizedDarcy’s law and general theory of anisotropic elasticity.Two criteria for the applicability of equivalent continuumapproach were established from the investigation: i) theexistence of properly defined REV (Representative ElementaryVolume) and ii) existence of the tensor in describing theconstitutive equation of fractured rock The equivalentcontinuum assumption cannot be accepted if any one of the abovetwo criteria is not met. Coefficient of variation and meanprediction error is suggested for the measures toquantitatively evaluate the errors involved in scale dependencyand tensor characteristic evaluation.</p><p>Equivalent permeability and mechanical properties (includingelastic modulus and Poisson’s ratios) determined onrealistic fracture network show that the presence of fracturehas a significant effect on the equivalent properties. Theresults of permeability, elastic moduli and Poisson's ratioshow that they narrow down with the increase of scale andmaintain constant range after a certain scales with someacceptable variation. Furthermore, Investigations of thepermeability tensor and compliance tensor in the rotated modelshow that their tensor characteristics are satisfied at acertain scale; this would indicate that the uses of theequivalent continuum approach is justified for the siteconsidered in this study.</p><p>The unique feature of the thesis is that it gives asystematic treatment of the homogenization and upscaling issuesfor the hydraulic and mechanical properties of fractured rockswith a unified approach. These developments established a firmfoundation for future application to large-scale performanceassessment of underground nuclear waste repository byequivalent continuum analysis.</p><p><b>Keywords :</b>Equivalent continuum approach, Equivalentproperty, Representative Elementary Volume (REV), DistinctElement Method, Discrete Fracture Network (DFN)</p>

The general principles of continuum mechanics such as conservation of mass, conservation of momenta, first and second law of thermodynamics are applicable to all materials irrespective of their internal constitutions. These principles alone do not provide sufficient equations to obtain solutions for any boundary value problems. The additional equations are provided by the constitutive laws. There are many groups of constitutive theories. Of them, the theory of plasticity describes rate independent nonlinear and inelastic behavior of materials. A plasticity-based constitutive law is proposed herein for geological materials. The model, however, may also be used for other frictional materials. A generalized approach is followed in formulating the proposed constitutive model. The technique can be used to construct plasticity-based constitutive models for any other materials. A series of laboratory tests are performed on cubical soil specimens using a truly triaxial testing device. The testing device is such that the samples can be subjected to a general three-dimensional state of stress. The test data is used to determine the material constants associated with the proposed constitutive model. The model is then verified by back-predicting the stress-strain curves obtained from the laboratory. As a final step, the proposed constitutive model is implemented into a three-dimensional finite element procedure. A number of boundary value problems are analyzed using the proposed model. The results are compared with the observation. It is found that the proposed model can effectively characterize the nonlinear and inelastic response of frictional materials. Although the proposed model is investigated with respect to soils, it can also be applied for concrete, rocks, etc.