1,723,840 research outputs found
Optimal Skateboard Geometry for Maximizing Ollie Height: a Multi-Phase Direct Collocation Optimization Study
No full textSkateboarding involves a human controlling a four wheeled vehicle that is steered by tilting the standing surface. The riding mechanics of skateboarding have been well reported [2, 3]. The sport also includes aerial maneuvers such as jumping of stairs, flying off ramps and flipping and rotating the skateboard. The most basic aerial trick is called the ollie. The athlete jumps up while pushing down on the back end of the skateboard’s tail, causing a rotation about the back axle. The upward acceleration due to the rotation together with the tail-ground impact cause the skateboard to go airborne. Midair the athlete drags the skateboard up through frictional contact and levels it out to land the trick. The most concrete performance measure of the ollie is height according to the Olympic judging criteria [4]. To reach maximum height the dynamics such as impact, dynamic response, and torque production are dependent on shape, inertia and mass, which gives reason to assume an optimal shape exists. This leads to the research question: What are the optimal geometric and inertial parameters of a skateboard for an Olympic athlete to reach maximal ollie height. The skateboard geometry is optimized through multiphase direct collocation with the objective of maximal ollie height. A parameterized model is created with scaling mass and inertia properties such that the geometry of the skateboard. Modelling the dynamics of the ollie including impact and friction are done with a point mass human controller that is kineticly and kinematicly mapped to a counter movement jump. A simplistic contact implicit impact scheme is made for a higher order optimization. The ollie height is improved by changing the mass and inertia properties of the skateboard. Multiple optimal board shapes are generated for example a skateboard with a smaller wheelbase can reach higher ollie height compared to an industry standard skateboard.https://github.com/mechmotum/ollie-optimization Github repository with code and data https://www.youtube.com/watch?v=jw5DmNnvD7c Video made of found optimization trajectoriesBiomedical Engineerin
Ollie Jones, 2015
No full textOllie Jones shares his experiences growing up and living in Lake County, Tennesse
Ollie Morris Letter
Get PDFA letter sent by Ollie Morris from Fort Bragg, North Carolina on July 12, 1943 to the First Christian Church of Morehead, Kentucky.https://scholarworks.moreheadstate.edu/mfcc_ww2_letters/1104/thumbnail.jp
Ollie M. Lyon Letter
Get PDFA letter sent by Ollie M. Lyon from Fort Bragg, North Carolina on July 12, 1943 to the First Christian Church of Morehead, Kentucky.https://scholarworks.moreheadstate.edu/mfcc_ww2_letters/1012/thumbnail.jp
Ollie M. Lyon Letter
Get PDFA letter sent by Ollie M. Lyon on August 22, 1943 to the First Christian Church of Morehead, Kentucky.https://scholarworks.moreheadstate.edu/mfcc_ww2_letters/1011/thumbnail.jp
Ollie M. Lyon Letter
Get PDFA letter sent by Captain Ollie M. Lyon from Camp Campbell, Kentucky on March 24, 1943 to the First Christian Church of Morehead, Kentucky.https://scholarworks.moreheadstate.edu/mfcc_ww2_letters/1032/thumbnail.jp
Ollie Tysman : Grand Haven veteran and commercial fisherman
No full textOllie (Allie) Tysman was a veteran of World War I and fought in France. Prior to the war, he enlisted in Co. F in 1913 and served on boarder patrol in Texas. In this interview, Ollie tells many stories about his fellow servicemen. He also discusses the birth of the American Legion Post in Grand Haven. After the war, Ollie became a commercial fisherman in the Grand Haven area
Oral History Interview: Ollie Bradshaw
Get PDFThis interview is one of series conducted concerning the Oral History of Appalachia. Ollie Bradshaw was a resident of Ironton, Ohio. In this interview, she discusses her family, community life, courtship, weddings, the Great Depression, the flood of 1937, and rural medicine.https://mds.marshall.edu/oral_history/1216/thumbnail.jp
Letter from Ollie J. Akel, December 4, 1967
No full textLetter from Ollie J. Akel to Fayez Sayegh, December 4, 1967, regarding his appearance on the David Susskind show and the Arab-Israeli conflict
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