The purpose of this study was to investigate the effect of variations in the alignment of the feet on scrum kinetics during machine scrummaging. Twenty nine rugby forwards from amateur-level teams completed maximal scrum efforts against an instrumented scrum machine, with the feet in parallel and non-parallel positions. Three-dimensional forces, the moment about the vertical axis and sagittal plane joint angles were measured during the sustained pushing phase. There was a decrease in the magnitude of the resultant force and compression force in both of the non-parallel conditions compared to parallel and larger compression forces were associated with more extended hip and knee angles. Scrummaging with the left foot forward resulted in the lateral force being directed more towards the left and the turning moment becoming more clockwise. These directional changes were reversed when scrummaging with the right foot forward. Scrummaging with the right foot positioned ahead of the left may serve to counteract the natural clockwise wheel of the live scrum and could be used to achieve an anti-clockwise rotation of the scrum for tactical reasons. However, this would be associated with lower resultant forces and a greater lateral shear force component directed towards the right.

Systematic review and meta-analysis.

-Engineers and scientists are often faced with the problem of objectively comparing time histories of measured and/or simulated data. This paper presents a reliable and intuitive validation metric for use in the validation process. The proposed validation metric is able to quantify the agreement/disagreement between deterministic system response quantities of interest obtained from measurements on a physical system and predictions from a mathematical model. The validation metric is based on the relative error and the challenges concerning the use of the relative error on periodic signals are addressed. The validation metric is compared to similar metrics and their advantages and limitations are discussed. The results show that the proposed validation metric gives a comprehensive error that is able to quantify the agreement between two periodic signals and is easily interpretable.

Stability of the resulting construct should be considered when selecting an implant. Our results provide evidence that fixation via pin-PMMA or SOP provide similar stability for L7-S1 fracture-luxation. In this context, other factors become more important in selecting the fixation method.

This article considers the mathematical modelling of the spring force of three interconnected rolling diaphragm type air springs used on a 40-ton tri-axle semi-trailer. The aim of the air spring model is to obtain a validated mathematical model that can be used in full vehicle multi-body dynamic simulations. The model considers the flow effects in the pipes connecting the three air springs as well as the mass transfer between them. Comparisons with experimental results show that the proposed mathematical model of the interconnected air springs is indeed able to accurately predict the pressures and forces of the air springs.