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升级   47.37% TA的每日心情 | 难过 2015-2-4 10:21 |
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签到天数: 2 天 [LV.1]初来乍到
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2#
发表于 2015-2-3 20:20
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lzp01
:Our basic model has two parts: to find a half-pipe shape that can maximize
vertical air, and to adapt the shape to maximize the possible total angle of
rotation. In an extended model, we analyze the snowboarder’s effect on
vertical air and on rotation. Finally, wediscuss the feasibility and the tradeoffs
of building a practical course.
The major assumption is that resistance includes the friction of snow plus
air drag, with the former proportional to the normal force. We find air drag
negligible.
We first obtain and solve a differential equation for energy lost to friction
and drag based on force analysis and energy conservation. We calculate
vertical air by analyzing projectile motion. We then calculate the angular
momentumbefore the flight and discuss factors influencing it. In an extended
model, we take the snowboarder’s influence into account.
We compare analytical and numerical results with reality, using default
parameters; wevalidate that our method is correct and robust. We analyze the
effects on vertical air of width, height, and gradient angle of the half-pipe. We
find that a wider, steeper course with proper depth and the path of a skilled
snowboarder are best for vertical air. Using a genetic algorithm, we globally
optimize the course shape to provide either the greatest vertical air or maximal
potential rotation; there is a tradeoff. Implementing a hybrid scoring system
as the objective function, we optimize the course shape to a “half-blood”
shape that would provide the eclectically best snowboard performance.
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