4 resultados para Stochastics, Brownian Motion, Polymer Physics, Computational Physics, Hydrodynamics

em Deakin Research Online - Australia


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This project uses methods of terrain representation, creation and realism described in literature. We find that using a combination of Fractional Brownian Motion and procedural formation of rivers via squig curves to form initial terrain, with hydraulic erosion for post processing, we have full control over the style of terrain: from jagged mountains to flat regions; and the phase of river from tightly rock controlled to flood plain regions.

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Geometric object detection has many applications, such as in tracking. Particle tracking microrheology is a technique for studying mechanical properties by accurately tracking the motion of the immersed particles undergoing Brownian motion. Since particles are carried along by these random undulations of the medium, they can move in and out of the microscope's depth of focus, which results in halos (lower intensity). Two-point particle tracking microrheology (TPM) uses a threshold to find those particles with peak, which leads to the broken trajectory of the particles. The halos of those particles which are out of focus are circles and the centres can be accurately tracked in most cases. When the particles are sparse, TPM will lose certain useful information. Thus, it may cause inaccurate microrheology. An efficient algorithm to detect the centre of those particles will increase the accuracy of the Brownian motion. In this paper, a hybrid approach is proposed which combines the steps of TPM for particles in focus with a circle detection step using circular Hough transform for particles with halos. As a consequence, it not only detects more particles in each frame but also dramatically extends the trajectories with satisfactory accuracy. Experiments over a video microscope data set of polystyrene spheres suspended in water undergoing Brownian motion confirmed the efficiency of the algorithm.

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 The last 20 years have been exciting times for scientists working with charismatic marine mega-fauna. Here recent advances are reviewed. There have been advances in both data gathering and data-analysis techniques that have allowed new insights into the physiological and behavioural ecology of free-ranging mega-faunal species; some marine mega-faunal species have now become model organisms for cutting edge approaches to identify the underlying mathematical properties of animal search patterns and hence the underlying behavioural processes (e.g. Levy flight versus Brownian motion); the implications of climate change have started to become more apparent with extended time-series of animal movements, abundance and performance; conservation issues have become integrated into marine planning and have resulted in the advent of extended networks of marine protected areas (MPAs) as well as large MPAs that span many 100,000 km2; and collaborative crossdisciplinary teams have started to reveal the importance of ocean currents in animal dispersal, the ontogeny of migration and population genetic structure. Looking to the future, increased data availability (e.g. through data sharing) will likely allow more holistic across-taxa analyses to become routine.
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