189 research outputs found
A Unified Task Priority Control Framework Design for Autonomous Underwater Vehicles
Get PDFIn this thesis, we investigate the problem of bringing various behaviours of Autonomous Underwater Vehicles under a common control framework. Thereby, we propose a unified guidance and control framework for AUVs based on the task priority control approach. This incorporate various behaviors such as path following, terrain following, obstacle avoidance, as well as homing and docking to stationary and moving docking stations. The integration of homing and docking maneuvers into the task priority framework is thus a novel contribution of this thesis. This integration allows, for example, to execute homing maneuvers close to uneven seafloor or obstacles, ensuring the safety of the AUV by giving the highest priority to the safety tasks. Furthermore, the proposed approach tackles a wide range of scenarios without ad hoc solutions. Indeed, the proposed approach is well suited for both the emerging trend of resident AUVs, which stay underwater for a long period inside garage stations, exiting to perform inspection and maintenance missions and homing back to them, and for AUVs that are required to dock to moving stations such as surface vehicles, or towed docking stations. The proposed techniques are further studied in a simulation setting, taking into account the rich number of aforementioned scenarios
An observation of ritual painting in Bali and its implications for the teaching and learning of art
Get PDFThe traditional painters of Kamasan, Bali, Indonesia, have a precise schema for the paintings they produce. They live in a close community, which seems to outsiders to be peaceful and cohesive. Painting technique has been taught by parents to children, and preserved relatively unchanged for centuries. What can be learned by an artist from another culture, about Balinese technique and lifestyle, that could be of use to painting and educational practise? As an artist/educator who had, to some degree, learned to abhor ritual, became bored easily with repetition, and saw self-expression as the main reason for art production, I was personally challenged by going to Kamasan and working with a painting family there. Throughout the process of working in Bali, and reflecting on ritual, my philosophy has changed. This thesis describes some of my experiences as a student in Bali. Based on my subsequent reflections upon return to Canada proposes that increased acceptance of ritual may be beneficial for art education practise
Graph Theoretic Analysis of Brain Connectomics in Multiple Sclerosis: Reliability and Relationship to Cognition
Get PDFResearch suggests that disruption of brain networks might explain cognitive deficits in multiple sclerosis (MS). The reliability and effectiveness of graph-theoretic network metrics as measures of cognitive performance were tested in 37 people with MS and 23 controls. Specifically, relationships to cognitive performance (linear regression against the Paced Auditory Serial Addition Test [PASAT-3], Symbol Digit Modalities Test [SDMT] and Attention Network Test [ANT]) and one-month reliability (using the intra-class correlation coefficient [ICC]) of network metrics were measured using both resting-state functional and diffusion MRI data. Cognitive impairment was directly related to measures of brain network segregation and inversely related to network integration (prediction of PASAT-3 by small-worldness, modularity, characteristic path length, R2=0.55; prediction of SDMT by small-worldness, global efficiency and characteristic path length, R2=0.60). Reliability of the measures over one month in a subset of 9 participants was mostly rated as good (ICC>0.6) for both controls and MS patients in both functional and diffusion data but was highly dependent on the chosen parcellation and graph density, with the 0.2-0.5 density range being the most reliable. This suggests that disrupted network organisation predicts cognitive impairment in MS and its measurement is reliable over a 1-month period. These new findings support the hypothesis of network disruption as a major determinant of cognitive deficits in MS and the future possibility of the application of derived metrics as surrogate outcomes in trials of therapies for cognitive impairment
A visible-infrared imaging spectrometer for planetary missions
Get PDFThis final report summarizes the design effort for the construction of a visible-infrared imaging spectrometer for planetary missions, funded by NASA under the Planetary Instrument Definition and Development Program. The goal was to design and develop a prototype brassboard pushbroom imaging spectrometer covering the 0.35 gm to 2.5 gm spectral region using a simplified optical layout that would minimize the size, mass and parts count of the instrument by using a single holographic grating to disperse and focus light from a single slit onto both the infrared and visible focal plane arrays. Design approaches are presented and analyzed, along with problems encountered and recommended solutions to those problems. In particular, a new type of grating, incorporating two sets of rulings and a filter in a layered structure, is presented for further development
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