Wheel slip is a common problem in planetary rover exploration tasks. During the current Mars Exploration Rover (MER) mission, the Spirit rover almost became trapped on a dune because of wheel slip. As rover missions on harsh terrains expand in scope, mission success will depend not only on rover safety, but also alacrity in task completion. Speed combined with exploration of varied and difficult terrains, the risk of slip increases dramatically. We first characterize slip performance of a rover on harsh terrains by implementing a novel High Fidelity Traversability Analysis (HFTA) algorithm in order to provide slip prediction and detection capabilities to a planetary rover. The algorithm, utilizing path and energy cost functions in conjunction with simulated navigation, allows a rover to select the best path through any given terrain by predicting high slip paths. Integrated software allows the rover to then accurately follow a designated path while compensating for slippage, and reach intended goals independent of the terrain over which it is traversing. The algorithm was verified using ROAMS, a high fidelity simulation package, at 3.5x real time speed. We propose an adaptive path following algorithm as well as a human-trained neural network to traverse multiple harsh terrains using slip as an advantage. On a near-real-time system, and at rover speeds 15 times the current average speed of the Mars Exploration Rovers, we show that the adaptive algorithm traverses paths in less time than a standard path follower. We also train a standard back-propagation neural network, using human and path following data from a near-real-time system. The neural network demonstrates it ability to traverse new paths on multiple terrains and utilize slip to minimize time and path error.

Thesis (M.A. Sc.)--University of Toronto, 2004. / Adviser: G.M.T. D'Eleuterio.

Thesis (Ph. D.)--University of California, San Diego, 2008. / Title from first page of PDF file (viewed September 22, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 202-225).

In this work I redesign a device used in the fiberglass sheet molding with roving. The device cuts the roving in pieces of approximately six or seven centimeters and lays them on the mold of the part to be made. Today these cutters have to be attached to the chuck of a regular handheld electric drill. The description of this task from an ergonomic standpoint revealed several points that deserved to be studied and improved. One of the most significant problems concerns the operator s position during sheet molding, which involves muscular and bone injury risk. This analysis serves as a basis for the designing of a new roving cutter that improves the operating conditions. The main goal of this work is to create alternatives for the development of fiberglass roving cutters. Such a study is relevant because it is based on the following three main aspects: (i) a better understanding of the operator s role in the work of machinery like hand-held electric drills; (ii) the implementation of an interdisciplinary project bringing together the areas of Mechanical Engineering, Industrial Designing, Production Engineering, and Materials Engineering; (iii) the opening for new research on industrial tools and development of new product designs. / O estudo que aqui se apresenta é um redesenho de um dispositivo que hoje é utilizado nos trabalhos e nos processos de laminação de peças em fibras de vidro, onde utilizam-se os fios de fibra de vidro, chamados de roving . Este dispositivo faz o corte dos fios em pedaços de tamanho aproximado de seis a sete centímetros, e joga estes em cima do molde da peça a ser laminada. Atualmente o dispositivo para ser utilizado, deve ser acoplado ao mandril de uma furadeira elétrica manual comum. A descrição das tarefas a partir de uma abordagem ergonômica apontou diversos problemas que mereciam ser estudados. Um dos mais significantes problemas está relacionado com a posição com que o operador trabalha durante o processo de laminação, e isso traz a ele sérios riscos de lesões músculo-esqueléticas. Tal pesquisa descritiva embasou a formulação da hipótese de melhoria da execução da tarefa do operador do dispositivo através do desenho de uma nova máquina destinada para a laminação com fios de fibra de vidro (roving). O objetivo do presente estágio do trabalho, portanto, é a geração de alternativas formais para o desenvolvimento da máquina para o corte do roving . A relevância do presente estudo repousa em três aspectos principais: (i) um maior conhecimento dos aspectos humanos no trabalho com máquinas do tipo de furadeiras elétricas manuais; (ii) a implementação de um projeto interdisciplinar que reúne diferentes áreas de atuação como a Engenharia Mecânica, Desenho Industrial, Engenharia de Produção e Engenharia de Materiais. (iii) a abertura de um campo de pesquisa e desenvolvimento para projetos de ferramentas industriais e desenho de produtos.

No description available.

The aim of this work is the development of mechanical models on a mesoscopic level for the analytical description of the material properties of textile reinforced concrete (TRC). For the modelling of the heterogeneous structure of TRC the concept of representative volume elements (RVE) is used. RVEs are representative for the mesoscopic structure. The overall material behaviour on the macroscopic level is obtained by means of homogenisation of the heterogeneous material behaviour on the mesoscopic level. Based on the micro mechanical solution of the elastic field of an ellipsoidal inclusion according to Eshelby a model for the determination of the material behaviour for multi-directional reinforced finegrained concrete is developed. An effective field approximation considers the interaction of the differentially orientated reinforcements in an averaged sense. Microcracks are included by additional strains in the representative volume element. The average interaction between the microcracks and the reinforcements is considered by an effective field approximation. As a criteria for the initiation of the macro cracking a critical microcrack density parameter is implemented in the mechanical model. The microcracks accumulate to macrocracks if the microcrack density parameter in the RVE exceeds this critical value. For the mechanical modelling of the bond behaviour between roving and matrix after macro cracking a multiple linear shear stress-slip relation is used. This shear stress-slip relation considers adhesion, damage and failure of the interface between roving and matrix. Hence experimentally measured pullout force-displacement curves can be simulated realistically. / Gegenstand dieser Arbeit ist die Entwicklung mechanischer Modelle auf der Mesoebene zur analytischen Beschreibung des makroskopischen Materialverhaltens von textilbewehrtem Feinbeton. Für die Modellierung der heterogenen Struktur wird das Konzept der repräsentativen Volumenelemente (RVE), die für die Mesostruktur des betrachteten Verbundwerkstoffes repräsentativ sind, verwendet. Der Übergang von dem heterogenen Materialverhalten auf der Mesoebene zum mittleren Materialverhalten auf der Makroebene erfolgt mittels Homogenisierung. Auf Basis der mikromechanischen Grundlösung für ellipsoidförmige Einschlüsse nach Eshelby wird ein Modell entwickelt, das die Ermittlung des Materialverhaltens von multidirektional bewehrtem Feinbeton ermöglicht. Durch die Anwendung einer Effektive-Feld-Theorie wird die gegenseitige Beeinflussung der unterschiedlich orientierten Bewehrungen in einem gemittelten Sinn betrachtet. Die ab einer bestimmten makroskopischen Beanspruchung entstehenden Mikrorisse berücksichtigt das mechanische Modell über einen durch die Mikrorisse hervorgerufenen zusätzlichen Verzerrungsanteil im RVE. Mittels der verwendeten Effektive-Feld-Theorie kann eine mittlere Beeinflussung zwischen den Mikrorissen und der Rovingbewehrung erfasst werden. Für den Übergang von der Mikrorissbildung zur Makrorissbildung wird für das mechanische Modell der Begriff einer maximalen Mikrorissdichte eingeführt. Überschreitet die Mikrorissdichte im RVE diesen maximalen Wert, vereinigen sich die Mikrorisse zu Makrorissen. Zur Beschreibung des mechanischen Verbundverhaltens zwischen Roving und Matrix beim Rovingauszug am Makroriss wird eine multilineare Schubspannungs-Schlupf-Beziehung verwendet, welche die Schädigung des Roving-Matrix-Verbundes bis hin zum vollständigen Versagen erfasst. Damit lassen sich experimentell ermittelte Kraft-Verformungskurven an Zugproben wirklichkeitsnah abbilden.

Options for tracking dynamic underwater targets using optical methods is currently limited. This thesis examines optical reflectance intensities utilizing Lambert’s Reflection Model and based on a proposed underwater laser tracking system. Numerical analysis is performed through simulation to determine the detectable light intensities based on relationships between varying inputs such as angle of illumination and target position. Attenuation, noise, and laser beam spreading are included in the analysis. Simulation results suggest optical tracking exhibits complex relationships based on target location and illumination angle. Signal to Noise Ratios are a better indicator of system capabilities than received intensities. Signal reception does not necessarily confirm target capture in a multi-sensor network. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Leakage and blockage of oil and gas pipeline systems, water pipelines, pipe-work of process plants and other pipe networks can cause serious environmental, health and economic problems. There are a number of non-destructive testing (NDT) methods for detecting these defects in pipeline systems such as radiographic, ultrasonic, magnetic particle inspection, pressure transient and acoustic wave methods. In this study, the acoustic wave method and a modal frequency technique, which based on a roving mass method, are used. The aim of the thesis is to employ acoustic wave propagation based methods in conjunction with stationary wavelet transform (SWT) to identify leakage and blockage in pipe systems. Moreover, the research is also aimed at using the difference of modal frequencies of fluid-filled pipes with and without defects and a roving mass, and consequently, to develop a roving mass-based defect detection method for pipelines. In the study, the acoustic finite-element analysis (AFEA) method is employed to simulate acoustic wave propagation in small and large air-filled water-filled straight pipe and pipe networks with leakage and blockage but without flow. Computational fluid dynamics (CFD) analysis was also employed to simulate acoustic wave propagation in air-and water-filled pipes with flow, leakage and blockage. In addition, AFEA was used to predict the modal frequencies of air- and water-filled pipes with leakage and blockage in the presence of a roving mass that was traversed along the axis of the pipes. Experimental testing was conducted to validate some of the numerical results. Two major experiments were performed. The first set of experiments consisted of the measurement of acoustic wave propagation in a straight air-filled pipe with leakage and blockage. The second set of experiments concerned the measurement of acoustic wave propagation in an air-filled pipe network comprising straight pipe, elbows and T-piece and flange. The AFEA and CFD analysis of fluid-filled pipe can be used to simulate the acoustic wave propagation and acoustic wave reflectometry of a fluid-filled pipe with leakage and blockage of different sizes down to a small leakage size of 1mm diameter and a blockage depth of 1.2mm in a pipe. Similarly, the AFEA method of a static fluid-filled pipe can be used to simulate acoustic wave modal frequency analysis of a fluid-filled pipe with leakage and blockage of different sizes down to a leakage of 1mm diameter and a blockage depth of 1.2mm. Moreover, the measured signal of acoustic wave propagation in an air-filled can be successfully decomposed and de-noised using the SWT method to identify and locate leakages of different sizes down to 5mm diameter, and small blockage depth of 1.2mm. Also, the SWT approximation coefficient, detail and de-noised detail coefficient curves of an air-filled pipe with leakage and blockage and a roving mass give leakage and blockage indications that can be used to identify, locate and estimate the size of leakage and blockage in a pipe.

The hereby presented thesis pursues the occupations of puppeteers, gymnasts, vendors, blade sharpeners and changes of life strategies of itinerant lineages between the late 18th and early 20th Centuries. Above all, the research was anchored at various registers - firstly comprising registry offices, censuses, registers of homestead participants or residence applications. These were supplemented by the then public press, remembrances of contemporaries and other sources. The historical and demographical analyses based upon genealogical outputs were the dominant methodological background, the subject of which primarily became the characteristics of itinerant individuals and their place within society. The author also inquired into their ethnic origins and specific ways of earning one´s living. The pivot of this treatise, nonetheless, was to reveal true historical circumstances having once brought into life a number of widespread clan legends. Neither marriage strategies were omitted as they provided proof of certain behavioural patterns of both the itinerant and settled individuals. Last but not the least, attention was paid to the sojourn and life en route within this roving peripheral community, the presupposed uniqueness of which was fully proved in every respect.

Für die elektrochemische Mikrobearbeitung superharter Werkstoffe, die Herstellung von faserbasierten Sensoren und die komplexe Funktionalisierung von faserverstärkten, polymeren Verbundwerkstoffen werden endlose Kohlenstoffeinzelfasern benötigt. Kohlenstofffasern werden in den jeweiligen Herstellungsprozessen (PAN und Pech) immer nur im Bündel gefertigt und angeboten. Einzelne Kohlenstofffasern sind nicht verfügbar. Für die Vereinzelung von Kohlenstofffasern aus dem Bündel wurden verschiedene Verfahren voruntersucht. Anschließend wurde auf Basis der Verfahren mit dem höchsten Vereinzelungspotenzial eine Vereinzelungsanlage aufgebaut. Die ersten Untersuchungen mit Hilfe der Vereinzelungsanlage zielten auf die Teilung von Faserbündeln als Vorstufe zu einer Einzelfaser ab. Die kontinuierliche Teilung von Bündeln konnte auf diese Weise erfolgreich durchgeführt werden. Die weitere Teilung halbierter Bündel wird aktuell untersucht. Halbierte Bündel können bereits in textilen Prozessen weiterverarbeitet oder für die Beschichtung genutzt werden. Auf diese Weise ist es möglich die Garnfeinheit der Rovings zu verringern und feinere Rovings als derzeit am Markt verfügbar anzubieten.