Exploring Topological Environments

Simultaneous localization and mapping (SLAM) addresses the task of incrementally building a map of the environment with a robot while simultaneously localizing the robot relative to that map. SLAM is generally regarded as one of the most important problems in the pursuit of building truly autonomous mobile robots. This thesis considers the SLAM problem within a topological framework, in which the world and its representation are modelled as a graph. A topological framework provides a useful model within which to explore fundamental limits to exploration and mapping. Given a topological world, it is not, in general, possible to map the world deterministically without resorting to some type of marking aids. Early work demonstrated that a single movable marker was sufficient but is this necessary? This thesis shows that deterministic mapping is possible if both explicit place and back-link information exist in one vertex. Such 'directional lighthouse' information can be established in a number of ways including through the addition of a simple directional immovable marker to the environment. This thesis also explores non-deterministic approaches that map the world with less marking information. The algorithms are evaluated through performance analysis and experimental validation. Furthermore, the basic sensing and locomotion assumptions that underlie these algorithms are evaluated using a differential drive robot and an autonomous visual sensor

Grouping-Enabled and Privacy-Enhancing Communications Schemes for VANETs

Open Access Bookpublished_or_final_versio

Effects of a brief action and coping planning intervention on completion of preventive exercises prescribed by a physiotherapist among people with knee pain

Objectives: The present study aimed to test the efficacy of action and coping planning in promoting engagement with preventive exercises among a sample of people with knee pain. Design: Experimental trial. Methods: Individuals who presented to a physiotherapist with knee pain (N = 373, 57% female; M age = 31.54, SD = 10.06, age range = 18-69 years) completed two assessments separated by 14 days. At baseline, participants completed measures of severity of problems associated with the knee (e.g., pain, symptoms) and past behavior. Subsequently, participants were randomly assigned to an action and coping planning or control group. Two weeks later, participants retrospectively reported their preventive exercise behavior over the past 14 days. Analyses revealed that the experimental group reported a higher number of preventive exercise sessions over the 14. day period when compared with the control group. Results: Participants who planned action and coping strategies reported a greater frequency of completed preventive exercises over a 2-week period than people who did not. Conclusions: The results of this study underscore the importance of action and coping planning for the enactment of preventive exercises that are designed to manage or prevent knee pain

Interfacial properties between CoO (100) and Fe(3)O(4) (100)

Using molecular beam epitaxy 1-20 ML thick CoO (100) films were grown monolayer by monolayer on Fe(3)O(4) (100) substrates. The stoichiometry of the films was verified by low-energy-electron diffraction and reflection-high-energy-electron diffraction patterns, as well as x-ray photoelectron spectroscopy. Auger measurements as a function of CoO film thickness indicated a layer-by-layer growth mode. Ultraviolet photoelectron spectroscopy (UPS) was used to monitor the thin film electronic properties. The evolution of the density of states in the O 2p/Fe 3d and O 2p/Co 3d bands exhibits a shift in the position of the CoO valence band for ultrathin films relative to bulklike thick films. The measured spectra (when aligned to cancel the band shift) are compared to models of the spectra that would be expected based on the bulk compounds, with and without additional interfacial electronic states. Electronic states at the Fe(3)O(4)-CoO interface have been identified, and their UPS spectrum has been determined

Control of Formation-Flying Multi-Element Space Interferometers with Direct Interferometer-Output Feedback

The long-baseline space interferometer concept involving formation flying of multiple spacecrafts holds great promise as future space missions for high-resolution imagery. A major challenge of obtaining high-quality interferometric synthesized images from long-baseline space interferometers is to accurately control these spacecraft and their optics payloads in the specified configuration. Our research focuses on the determination of the optical errors to achieve fine control of long-baseline space interferometers without resorting to additional sensing equipment. We present a suite of estimation tools that can effectively extract from the raw interferometric image relative x/y, piston translational and tip/tilt deviations at the exit pupil aperture. The use of these error estimates in achieving control of the interferometer elements is demonstrated using simulated as well as laboratory-collected interferometric stellar images