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Ray tracing large distributed datasets using ray cachesLittle, Christopher 09 March 2012 (has links)
Many large scale simulations now produce datasets that are signi cantly
larger than can typically be stored in memory on a visualization system. Visualization
algorithms then become ine ective and stall since the data must be
paged to disk. Recently, in-situ visualization has received renewed attention
for visualizing large datasets that are distributed among many processors during
a simulation. It takes advantage of the fact that the full dataset is already
in main memory, distributed among multiple processors. Visualization in this
environment then requires communication which can be more expensive than
disk access. The goal of this thesis was to develop an in-situ visualization
technique using ray tracing that employs ray caches to reduce communication
overhead. Ray caches attempt to replace a communication operation with a
less expensive cache search operation. A prototype implemented on Sharcnet
shows ray caching can signi cantly improve overall performance at a small cost
to image quality. / UOIT
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State of Charge and Range Estimation of Lithium-ion Batteries in Electric VehiclesKhanum, Fauzia January 2021 (has links)
Switching from fossil-fuel-powered vehicles to electric vehicles has become an international focus in the pursuit of combatting climate change. Regardless, the adoption of electric vehicles has been slow, in part, due to range anxiety. One solution to mitigating range anxiety is to provide a more accurate state of charge (SOC) and range estimation. SOC estimation of lithium-ion batteries for electric vehicle application is a well-researched topic, yet minimal tools and code exist online for researchers and students alike. To that end, a publicly available Kalman filter-based SOC estimation function is presented. The MATLAB function utilizes a second-order resistor-capacitor equivalent circuit model. It requires the SOC-OCV (open circuit voltage) curve, internal resistance, and equivalent circuit model battery parameters. Users can use an extended Kalman filter (EKF) or adaptive extended Kalman filter (AEKF) algorithm and temperature-dependent battery data. A practical example is illustrated using the LA92 driving cycle of a Turnigy battery at multiple temperatures ranging from -10C to 40C.
Current range estimation methods suffer from inaccuracy as factors including temperature, wind, driver behaviour, battery voltage, current, SOC, route/terrain, and much more make it difficult to model accurately. One of the most critical factors in range estimation is the battery. However, most models thus far are represented using equivalent circuit models as they are more widely researched. Another limitation is that any machine learning-based range estimation is typically based on historical driving data that require odometer readings for training.
A range estimation algorithm using a machine learning-based voltage estimation model is presented. Specifically, the long short-term memory cell in a recurrent neural network is used for the battery model. The model is trained with two datasets, classic and whole, from the experimental data of four Tesla/Panasonic 2170 battery cells. All network training is completed on SHARCNET, a resource provided by Canada Compute to researchers. The classically trained network achieved an average root mean squared error (RMSE) of 44 mV compared to 34 mV achieved by the network trained on the whole dataset. Based on the whole dataset, all test cases achieve an end range estimation of less than 5 km with an average of 0.29 km. / Thesis / Master of Applied Science (MASc)
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