Sprint acceleration training has been highly researched and found that resistance sleds are one of the most effective tools for maximizing training adaptations. The resistance sled is being used by many of the world leaders in athletic training but has yet to be researched for the kinetic and kinematic effects some of its key components cause. The aim of this study was to better understand the effects of the attachment height on the sled and sled rail material on the user's trunk lean and jerking effect caused by the sled. This was done because it was hypothesized that the attachment height has a direct impact on trunk lean and sled rail material has a direct impact on jerk caused by the sled. To test these assumptions, experimental and theoretical data was collected using a single subject study analyzing trunk lean and acceleration values of the sled. The results presented a significant decrease in trunk lean (more horizontal line of action) when the attachment height was raised. Additionally, no significant values were attained to support the assumption that by modifying the sled rail material, jerking effects will decrease. The results indicate that there is a direct correlation between attachment height and trunk lean. More research is needed to better understand the relationship between sled rail material and jerk.

The ability to control head orientation relative to the body is a multi-sensory process that mainly depends on three sensory pathways namely, proprioceptive, vestibular, and visual. A system to study the sensory integration of head orientation was developed and tested. A test seat with five-point harness was assembled to provide the passive postural support. A light-weight head-mount display (HMD) was designed for mounting multi-axis accelerometers and a mini- CCD camera to provide the visual input to virtual reality (VR) goggles with 39° horizontal field of view. A digitally generated sinusoidal signal was delivered to a motor-driven computer-controlled sled on a 6m linear railing system. A data acquisition system was designed to collect acceleration data. A pilot study was conducted to test the system. Four young healthy subjects were seated with their trunks fixed to the seat. Subjects received a sinusoidal anterior-posterior translation with peak acceleration of 0.06g at 0.1Hz and 0.12g at 0.2Hz, 0.5Hz and 1.1Hz. Four sets of visual conditions were randomly presented along with the translation. These conditions included eyes open looking forward, backward, and sideways, and also eyes closed. Linear acceleration data were collected from linear accelerometers placed on the head, trunk and seat and were processed using Matlab. The head motion was analyzed using Fast Fourier Transform (FFT) to derive gain and phase of head pitch acceleration relative to seat linear acceleration. A randomization test for two independent variables was used to test significance of visual and inertial effects on response gain and phase shifts. Results show that the gain was close to one with no significant difference among visual conditions across frequencies. The phase was shown to be dependent on the head strategy each subject used. The ability to control head orientation relative to the body is a multi-sensory process that mainly depends on three sensory pathways namely, proprioceptive, vestibular, and visual. A system to study the sensory integration of head orientation was developed and tested. A test seat with five-point harness was assembled to provide the passive postural support. A light-weight head-mount display (HMD) was designed for mounting multi-axis accelerometers and a mini- CCD camera to provide the visual input to virtual reality (VR) goggles with 39° horizontal field of view. A digitally generated sinusoidal signal was delivered to a motor-driven computer-controlled sled on a 6m linear railing system. A data acquisition system was designed to collect acceleration data. A pilot study was conducted to test the system. Four young healthy subjects were seated with their trunks fixed to the seat. Subjects received a sinusoidal anterior-posterior translation with peak acceleration of 0.06g at 0.1Hz and 0.12g at 0.2Hz, 0.5Hz and 1.1Hz. Four sets of visual conditions were randomly presented along with the translation. These conditions included eyes open looking forward, backward, and sideways, and also eyes closed. Linear acceleration data were collected from linear accelerometers placed on the head, trunk and seat and were processed using Matlab. The head motion was analyzed using Fast Fourier Transform (FFT) to derive gain and phase of head pitch acceleration relative to seat linear acceleration. A randomization test for two independent variables was used to test significance of visual and inertial effects on response gain and phase shifts. Results show that the gain was close to one with no significant difference among visual conditions across frequencies. The phase was shown to be dependent on the head strategy each subject used. / Mechanical Engineering

Dans cet article, nous proposons une nouvelle bibliothèque de techniques non linéaires pour accélérer l’équation de transport en ordonnées discrètes. Deux nouveaux types de méthodes d'accélération non linéaire appelées méthode de rééquilibrage spatialement variable (SVRM) et accélération de matrice de réponse (RMA), respectivement, sont proposées et étudiées. La première méthode, SVRM, est basée sur le calcul de la variation spatiale de premier ordre de l'équation de la balance des neutrons. RMA, est une méthode DP0 qui utilise la connaissance de l'opérateur de transport pour former une relation cohérente. Deux variantes distinctes de RMA, appelées respectivement Explicit-RMA (E-RMA) et Balance (B-RMA), sont dérivées. Les propriétés de convergence des deux méthodes d'accélération sont étudiées pour deux schémas d'itération différents de l'opérateur de transport de la méthode des caractéristiques (MOC) pour une dalle 1D, en utilisant une analyse spectrale et une analyse de Fourier. Sur la base des résultats de la comparaison 1D, seuls les outils RMA et CMFD ont été implémentés dans la bibliothèque. Les performances de RMA sont comparées à celles de CMFD en utilisant les tests 3D C5G7, ZPPR et UH12. Les schémas de résolution parallèles et séquentiels sont considérés. L'analyse des résultats indique que les deux variantes de RMA ont une efficacité et une stabilité améliorées par rapport au CMFD, pour les matériaux à diffusion optique. De plus, le RMA montre une amélioration importante de la stabilité et de l'efficacité lorsque la géométrie est décomposée spatialement. Pour obtenir des performances numériques optimales, une combinaison de RMA et de CMFD est suggérée. Une enquête plus approfondie sur l'utilisation et l'amélioration de la RMA est proposée. De plus, de nombreuses idées pour étendre les fonctionnalités de la bibliothèque sont présentées. / In this paper we propose a new library of non-linear techniques for accelerating the discrete-ordinates transport equation. Two new types of nonlinear acceleration methods called Spatially Variant Rebalancing Method (SVRM) and Response Matrix Acceleration (RMA), respectively, are proposed and investigated. The first method, SVRM, is based on the computation of the zeroth and first order spatial variation of the neutron balance equation. RMA, is a DP0 method that uses knowledge of the transport operator to form a consistent relationship. Two distinct variants of RMA, called Explicit-RMA (E-RMA) and Balance (B-RMA), respectively, are derived. The convergence properties of both acceleration methods are investigated for two different iteration schemes of the method of characteristics (MOC) transport operator for a 1D slab, using spectral and Fourier analysis. Based off the results of the 1D comparison, only RMA and CMFD were implemented in the library. The performance of RMA is compared to CMFD using the C5G7, ZPPR, and UH12 3D benchmarks. Both parallel and sequential solving schemes are considered. Analysis of the results indicates that both variants of RMA have improved effectiveness and stability relative to CMFD, for optically diffusive materials. Moreover, RMA shows great improvement in stability and effectiveness when the geometry is spatially decomposed. To achieve optimal numerical performance, a combination of RMA and CMFD is suggested. Further investigation into the use and improvement of RMA is proposed. As well, many ideas for extending the features of the library are presented.

No description available.