This thesis investigates and implements the sensor fusion necessary to autonomously reverse a full size truck and trailer system. This is done using a LiDAR mounted on the rear of the truck along with a RTK-GPS. It is shown that the relative angles between truck-dolly and dolly-trailer can be estimated, along with global position and global heading of the trailer. This is then implemented in one of Scania's test vehicles, giving it the ability to continuously estimate these states. A controller is then implemented, showing that the full scale system can be stabilised in reverse motion. The controller is tested both on a static reference path and a reference path received from a motion planner. In these tests, the controller is able to stabilise the system well, allowing the truck to do complex manoeuvres backwards. A small lateral tracking error is present, which needs to be further investigated.

In this thesis we investigate the existence and stability of periodic solutions of Hamiltonian systems with a discrete symmetry. The global existence of periodic motions can be proven using the classical techniques of the calculus of variations; our particular interest is in how the stability type of the solutions thus obtained can be determined analytically using solely the variational problem and the symmetries of the system -- we make no use of numerical or perturbation techniques. Instead, we use a method introduced in [41] in the context of a special case of the three-body problem. Using techniques from symplectic geometry, and specifically the Maslov index for curves of Lagrangian subspaces along the minimizing trajectories, we verify conditions which preclude the existence of eigenvalues of the monodromy matrix on the unit circle. We study the applicability of this method in two specific cases. Firstly, we consider another special case from celestial mechanics: the hip-hop solutions of the 2N-body problem. This is a family of Z_2-symmetric, periodic orbits which arise as collision-free minimizers of the Lagrangian action on a space of symmetric loops [14, 53]. Following a symplectic reduction, it is shown that the hip-hop solutions are brake orbits which are generically hyperbolic on the reduced energy-momentum surface. Secondly we consider a class of natural Hamiltonian systems of two degrees of freedom with a homogeneous potential function. The associated action functional is unbounded above and below on the function space of symmetric curves, but saddle points can be located by minimization subject to a certain natural constraint of a type first considered by Nehari [37, 38]. Using the direct method of the calculus of variations, we prove the existence of symmetric solutions of both prescribed period and prescribed energy. In the latter case, we employ a variational principle of van Groesen [55] based upon a modification of the Jacobi functional, which has not been widely used in the literature. We then demonstrate that the (constrained) minimizers are again hyperbolic brake orbits; this is the first time the method has been applied to solutions which are not globally minimizing. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2013-09-25 10:47:53.257

Multilevel inverters offer many well-known advantages for use in high-voltage and high-power applications, but they are also well suited for low-power applications. A single phase inverter is developed in this paper to deliver power from a residential-scale system of Photovoltaic panels to the utility grid. The single-stage inverter implements a novel control technique for the reversing voltage topology to produce a stepped output waveform. This approach increases the granularity of control over the PV systems, modularizing key components of the inverter and allowing the inverter to extract the maximum power from the systems. The adaptive controller minimizes harmonic distortion in its output and controls the level of reactive power injected to the grid. A computer model of the controller is designed and tested in the MATLAB program Simulink to assess the performance of the controller. To validate the results, the performance of the proposed inverter is compared to that of a comparable voltage-sourced inverter.

This thesis investigates the design of a local planning method for a reversing single joint tractor-trailer system that can be used in a sampling-based motion planner. The motion planner used is a Rapidly-exploring Random Tree (RRT) developed by Scania. The main objective of a local planning method is to generate a feasible path between two poses, which is needed when expanding the search tree in an RRT. The local planning method described in this thesis uses a set of curves, similar to Reeds-Shepp curves, feasible for a single joint tractor-trailer system. The curves are found by solving a constrained optimization problem that adheres to the kinematic model of the system. The reference for the tractor is generated by discretizing the path between curves. The reference for the trailer is generated by simulating the mission backwards where the curve radiuses are used as input. Simulating the mission backwards circumvents the instability of the system when reversing. The generated references are then compared to references generated by a lattice-based motion planner. The length of the references generated by the RRT are smaller than those generated by the lattice-based motion planner in simple open environments. The RRT had issues finding a path in cases where the environment was complex while the lattice-based motion planner found a path in every scenario. The computational time was significantly lower for the RRT in all simulations. The RRT generates all references between any two given poses while the lattice-based motion planner approximate the start and goal poses to the closest vertex in the search-space.  The references generated by the RRT did not perform optimally when small turns were needed along the curves due to the distance needed for maneuvering the tractor. Therefore, a new optimization problem has to be defined for which the small turns are considered.

Der Zusammenhang zwischen Lohnhöhe einerseits und Profit bzw. Profitrate andererseits gehört traditionell zur Grundlagenforschung der ökonomischen Theorie. In der kapitaltheoretischen Kontroverse der jüngeren Vergangenheit spielen Kurven, die diesen Zusammenhang wiedergeben, eine bedeutende Rolle. Hier geht es indes weniger um deren formale Eigenschaften, sondern eher darum, ihren ökonomischen Gehalt freizulegen und auf offene Fragen hinzuweisen.

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This thesis analyzes the economic health of the dining establishments in Downtown San Diego, CA, specifically in the vicinity of Petco Park. Opened in 2004, Petco Park is home to the San Diego Padres, a Major League Baseball franchise. In addition, it serves as a venue for outdoor concerts and shows. The venue is used for most of the year due to an expanded Major League Baseball schedule, especially compared to other professional sports. Much of the transformation of San Diego’s Downtown can be attributed to the late 1990’s East Village Revitalization Plan, which included municipal anchors like the San Diego Central Library, the San Diego Convention Center, and Petco Park. By looking at the restaurant industry as of 2019, this thesis strives to provide a better understanding of how an urban entertainment anchor provides grounds for mutually beneficial conditions to small businesses. Additionally, this thesis integrates the concept of economic health into the larger field of knowledge around urban professional sports stadia. Further, this thesis aims to burgeon a framework for taxonomic research of professional sports stadia.

Polarity-reversing affirmative particles are a phenomenon that has largely been overlooked in previous research. A polarity-reversing affirmative particle is used to express disagreement with the polarity of a preceding negative statement. It is a typical answer strategy in Swedish, German, Dutch as well as in French. In fact, findings from previous cross-linguistic studies suggest, though without further detail, that polarity-reversing affirmative particles are a phenomenon predominantly found in European and more specifically in Germanic languages (Da Milano 2004; Roelofsen & Farkas 2015; Moser 2018). The aim of this study is to examine the hypotheses presented in Moser (2018). The goals are to investigate the distribution of polarity-reversing affirmative particles in Europe on the one hand, and to examine the phenomenon in Swedish, German, Dutch and French from a diachronic perspective on the other hand. On the basis of these endeavors, this study is embedded in the framework of areal typology. This study brings forth highly interesting findings in view of the discussion of Standard Average European and the Charlemagne Sprachbund. / Polarity-reversing affirmative particles (sv. polaritetsomvändande affirmativa partiklar) är ett fenomen som har förbisetts i tidigare forskning. En polarity-reversing affirmative particle används för att uttrycka oenighet med ett negativt påstående. Det är en vanlig strategi i svenska, tyska, nederländska samt franska. Tidigare resultat från tvärspråkliga studier visar att polarity-reversing affirmative particles oftast förekommer i europeiska, mer specifikt germanska språk (Da Milano 2004; Roelofsen & Farkas 2015; Moser 2018). Denna studie ämnar undersöka resultaten från de ovannämnda studierna. Målet är således att undersöka distributionen av polarity-reversing affirmative particles i Europa samt att undersöka fenomenet i svenska, tyska, nederländska och franska från ett diakroniskt perspektiv. Denna studie anknyter till ett arealtypologiskt perspektiv. Resultaten påvisar intressanta rön med direkt relevans för Standard Average European och i den så kallade Charlemagne-arean.

Na análise global e local de sistemas dinâmicos assumimos, em geral, que as equações estão numa forma normal. Em presença de simetrias, as equações e o domínio do problema são invariantes pelo grupo formado por estas simetrias; neste caso, o campo de vetores é equivariante pela ação deste grupo. Quando, além das simetrias, temos também ocorrência de anti-simetrias - ou reversibilidades - as equações e o domínio do problema são ainda invariantes pelo grupo formado pelo conjunto de todas as simetrias e anti-simetrias; neste caso, o campo de vetores é reversível-equivariante. Existem muitos modelos físicos onde simetrias e anti-simetrias aparecem naturalmente e cujo efeito pode ser estudado de uma forma sistemática através de teoria de representação de grupos de Lie. O primeiro passo deste processo é colocar a aplicação que modela tal sistema numa forma normal e isto é feito com a dedução a priori da forma geral dos campos de vetores. Esta forma geral depende de dois componentes: da base de Hilbert do anel das funções invariantes e dos geradores do módulo das aplicações reversíveis-equivariantes. Neste projeto, nos concentramos principalmente na aplicação de resultados recentes da literatura para a construção de uma lista de formas gerais de aplicações reversíveisequivariantes sob a ação de diferentes grupos. Além disso, adaptamos ferramentas algébricas da literatura existentes no contexto equivariante para o estudo sistemático de acoplamento de células idênticas no contexto reversível-equivariante / In the global and local analysis of dynamical systems, we assume, in general, that the equations are in a normal form. In presence of symmetries, the equations and the problem domain are invariant under the group formed by these symmetries; in that case, the vector field is equivariant by the action of this group. When, in addition to the symmetries, we have the occurrence of anti-symmetries - or reversibility - the equations and the problem domain are still invariant by the group formed by the set of all symmetries and anti-symmetries; in this case, the vector field is reversible-equivariant. There are many physical models where both symmetries and anti-symmetries occur naturally and whose effect can be studied in a systematic way through group representation theory. The first step of this process is to put the mapping that model the system in a normal form, and this is done with the deduction of the general form of the vector field. This general form depends on two components: the Hilbert basis of the invariant function ring and also the generators of the module of the revesible-equivariants. In this work, we mainly focus on the applications of recent results of the literature to build a list of general forms of reversible-equivariant mappings under the action of different groups. We also adapt algebraic tools of the existing literature in the equivariant context to the systematic study of coupling of identical cells in the reversible-equivariant context