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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Design of an autonomous navigation system for a mobile robot

Paul, André. January 2005 (has links)
An autonomous navigational system for a mobile robot was developed based on a Laser-Range-Finder-based path planning and navigational algorithms. The system was enhanced by incorporating collision avoidance algorithms using data from a sonar sensor array, and further improved by establishing two virtual regions in front of the robot for obstacle detection and avoidance. Several virtual detector bands with varying dimensions were also added to the sides of the robot to check for rotational clearance safety and to determine the direction of rotation. The autonomous navigational system was tested extensively under indoor environment. Test results showed that the system performed satisfactorily in navigating the mobile robot in three structured mazes under indoor conditions. / An artificial landmark localization algorithm was also developed to continuously record the positions of the robot whilst it was moving. The algorithm was tested on a grid layout of 6 m x 6 m. The performance of the artificial landmark localization technique was compared with odometric and inertial measurements obtained using a dead-reckoning method and a gyroscope-corrected dead-reckoning method. The artificial landmark localization method resulted in much smaller root mean square error (0.033 m) of position estimates compared to the other two methods (0.175 m and 0.135 m respectively).
62

A HIGH PRECISION STUDY OF LI-ION BATTERIES

Smith, Aaron 02 April 2012 (has links)
Undesired reactions in Li-ion batteries, which lead to capacity loss, can consume or produce charge at either the positive or negative electrode. For example, the formation and repair of the solid electrolyte interphase consumes Li+ and e- at the negative electrode. Electrolyte oxidation at the positive electrode allows extra electrons (with corresponding electrolyte decomposition products) to be extracted at the electrode compared to the number which could be extracted in the absence of electrolyte oxidation. High purity electrolytes, various electrolyte additives, electrode coatings and special electrode materials are known to improve cycle life and therefore must impact coulombic efficiency. Careful measurements of coulombic efficiency are needed to quantify the impact of different battery materials on cell life time in only a few charge-discharge cycles and in a relatively short time. In order to make an impact on Li-ion cells for automotive and energy storage applications, where thousands of charge-discharge cycles are required, coulombic efficiency must be measured to an accuracy and precision of at least 0.01%. An instrument designed to make high-precision coulombic efficiency measurements on Li ion batteries is described in this thesis. Such measurements can be used to detect the influence of different electrode materials, voltage ranges, cell temperature, etc. on the performance of a cell. The effects of cycle induced and time-related capacity loss can be probed using experiments carried out at different C-rates. Precision differential voltage and capacity measurements can also be used to identify the different failure mechanisms that occur in full cells.
63

Improving Precision and Accuracy in Coulombic Efficiency Measurements of Lithium Ion Batteries

Bond, Toby Mishkin 02 October 2012 (has links)
Lithium-ion batteries have been used extensively over the past two decades in the portable consumer electronics industry. More recently, Li-ion batteries have become candidates for much larger-scale applications such as electric vehicles and energy grid storage, which impose much more stringent requirements on batteries, especially in terms of cell lifetime. In order to develop batteries with improved lifetimes, a means of quickly and accurately evaluating battery life is required. The use of coulombic efficiency (CE) is an important tool in this regard, which provides a way to quantify parasitic reactions occurring within the cell. As more stable battery chemistries are developed, the rates of parasitic reactions occurring in the cell become reduced, and differences in CE among cells become increasingly smaller. In order to resolve these differences, charger systems must be developed which can measure CE with increased precision and accuracy. This thesis investigates various ways to improve the precision and accuracy of CE measurements. Using the high-precision charger (HPC) at Dalhousie University (built in 2009) as a starting point, a new prototype charger was built with several modifications to the design of the existing HPC. The effect of each of these modifications is investigated in detail to provide a blueprint for the development of next-generation charger systems. This prototype charger shows greatly improved precision and accuracy, with CE results that are approximately four times more precise than those of the existing HPC and over an order of magnitude more precise than high-end commercially available charger systems
64

A Microclimate Analysis of a Niagara Peninsula Vineyard Using Solar Aspect as a Variable

Dixon, Philip G. 09 May 2012 (has links)
This study, based on data collected in 2006, examined the effect of microclimate, as solar aspect, on yield and quality parameters of Riesling vines of a vineyard in the Niagara Peninsula, Thirty Bench Winery, Beamsville, Ontario. Precision viticulture practices including GPS (Global Positioning System), GIS (Geographic Information System) and LIDAR (Laser Range Finder) were used to delineate the microclimate and categorize variations within the vineyard. Within GIS, slope and aspect analysis tools generated solar aspect data. Two different zones were identified and compared for yield and quality data. Monoterpene concentrations in grapes differed by solar aspect, with vines receiving elevated solar radiation showing increased monoterpene concentrations. Since monoterpenes are important to the aroma and flavour of Riesling wines, a difference could impact the quality of the wine produced. Overall, this work shows the potential of precision viticulture in the development of terroir –specific wine in the Niagara region.
65

Effect of fluid motion on movement performance and finger-force pattern during manipulation of Containers/Cups filled with Liquid

RAVALA, KALPANA 06 September 2011 (has links)
The purposes of this study were to: 1) evaluate how movement performance of the thumb and fingers were modified during manipulation of objects with and without fluids and 2) to quantify movement performance and accuracy during manipulation of objects, in two different modes of manipulation, i.e., pendulum and inverted pendulum. Twenty young healthy adults (age 24-35) were recruited and performed two predictable cyclic tracking tasks and episodic short-duration precision movement task. No change in movement performance observed in open-loop or episodic tasks. However, in closed-loop task, mode of manipulation (IP versus P) had a significant effect on amplitude consistency (P<0.001), and temporal accuracy (P<0.050).Fluid motion had a significant effect on RMS of index finger contact forces (p < 0.01) in episodic task. In conclusion, fluid motion had no significant effect on movement performance and accuracy. The quality of movement was better in pendulum mode than inverted pendulum movement.
66

Effect of fluid motion on movement performance and finger-force pattern during manipulation of Containers/Cups filled with Liquid

RAVALA, KALPANA 06 September 2011 (has links)
The purposes of this study were to: 1) evaluate how movement performance of the thumb and fingers were modified during manipulation of objects with and without fluids and 2) to quantify movement performance and accuracy during manipulation of objects, in two different modes of manipulation, i.e., pendulum and inverted pendulum. Twenty young healthy adults (age 24-35) were recruited and performed two predictable cyclic tracking tasks and episodic short-duration precision movement task. No change in movement performance observed in open-loop or episodic tasks. However, in closed-loop task, mode of manipulation (IP versus P) had a significant effect on amplitude consistency (P<0.001), and temporal accuracy (P<0.050).Fluid motion had a significant effect on RMS of index finger contact forces (p < 0.01) in episodic task. In conclusion, fluid motion had no significant effect on movement performance and accuracy. The quality of movement was better in pendulum mode than inverted pendulum movement.
67

Factors influencing adoption and use of precision agriculture

Adrian, Anne Mims Rainer, R. Kelly January 2006 (has links) (PDF)
Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.
68

Precision agriculture realizing increased profit and reduced risk through cost map and lightbar adoption /

Kayrouz, Benjamin Michael, January 2008 (has links)
Thesis (M.S.)--University of Kentucky, 2008. / Title from document title page (viewed on November 3, 2008). Document formatted into pages; contains: ix, 58 p. : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 55-57).
69

Wheat yield prediction modeling for localized optimization of fertilizer and herbicide application

Wagner, Nicole Catherine. January 2004 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Bruce D. Maxwell. Includes bibliographical references.
70

Three-dimensional photoelastic stress analysis of a free-end partial denture with a bottomed-out and non-bottomed-out parallel precision attachment

Arfaei, A. Hamid. January 1976 (has links)
Thesis (M.S.)--University of Michigan, Ann Arbor, 1976. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 128-134).

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