On the impact of receiver quantization on the performance of wireless communication systems

[摘要] The overall objective of this dissertation was to determine the influence of footwear sole hardness on slip initiation and falls. To achieve this goal, three separate studies were undertaken. The purpose of the first study was to determine the influence of sole hardness on peak utilized coefficient of friction (COFu) during walking. Ground reaction forces, full body kinematics, and subjective ratings of footwear slipperiness were obtained from 56 young adults while wearing hard and soft soled shoes. Peak COFu was significantly less when wearing hard soled shoes compared to when wearing soft soled shoes. The decrease in peak COFu was attributed to a decrease in total body center of mass (COM) acceleration prior to and immediately following initial contact. The purpose of the second study was to determine the influence of sole hardness on the probability of slip initiation. Forty young adults were randomized into hard and soft sole groups. Peak COFu was obtained during a non-slippery floor condition while slip probability was assessed during a slippery floor condition. Despite the lower COFu in the hard sole group, the proportion of slip events was found to be greater than the soft sole group. The purpose of third study was to investigate the influence of sole hardness on the probability of slip-induced falls. Slip characteristics and fall probability during a slippery floor trial were compared between hard and soft sole groups. The proportion of fall events in the hard sole group was not statistically different than the proportion of fall events in the soft sole group. In addition, no differences were observed between shoe groups for slip distance, average heel and COM slipping velocity. Collectively, the results of this dissertation support the premise that individuals wearing shoes with hard soles are at greater risk for slip initiation, but not greater risk of falls. Although individuals demonstrate gait adaptations to reduce the friction demand when wearing hard soled shoes that are perceived to be more slippery, these behavioral adaptations do not appear to decrease the risk of slips.

[发布机构] Rice University

[效力级别] Electrical engineering