1,841,826 research outputs found
Effects of run-up velocity on performance, kinematics, and energy exchanges in the pole vault
No full textCopyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.This study examined the effect of run-up velocity on the peak height achieved by the athlete in the pole vault and on the corresponding changes in the athlete's kinematics and energy exchanges. Seventeen jumps by an experienced male pole vaulter were video recorded in the sagittal plane and a wide range of run-up velocities (4.5-8.5 m/s) was obtained by setting the length of the athlete's run-up (2-16 steps). A selection of performance variables, kinematic variables, energy variables, and pole variables were calculated from the digitized video data. We found that the athlete's peak height increased linearly at a rate of 0.54 m per 1 m/s increase in run-up velocity and this increase was achieved through a combination of a greater grip height and a greater push height. At the athlete's competition run-up velocity (8.4 m/s) about one third of the rate of increase in peak height arose from an increase in grip height and about two thirds arose from an increase in push height. Across the range of run-up velocities examined here the athlete always performed the basic actions of running, planting, jumping, and inverting on the pole. However, he made minor systematic changes to his jumping kinematics, vaulting kinematics, and selection of pole characteristics as the run-up velocity increased. The increase in run-up velocity and changes in the athlete's vaulting kinematics resulted in substantial changes to the magnitudes of the energy exchanges during the vault. A faster run-up produced a greater loss of energy during the take-off, but this loss was not sufficient to negate the increase in run-up velocity and the increase in work done by the athlete during the pole support phase. The athlete therefore always had a net energy gain during the vault. However, the magnitude of this gain decreased slightly as run-up velocity increased
Robust pole assignment techniques via state feedback
No full textWe present a unifying computational framework to solve robust pole assignment problems for linear systems using state feedback. The new framework uses Sylvester equation based parametrizations of the pole assignment problems. The non-uniqueness of solutions is exploited by minimizing additionally sensitivity of closed-loop eigenvalues and the norm of the corresponding state feedback matrix. The solution methods rely on using gradient search based minimization techniques on suitably defined cost functions. The discussion of main functional and numerical aspects reveals many desirable features of the underlying algorithms which recommend them to serve as bases for robust numerical software implementations
Robust pole assignment for descriptor systems
No full textBy using a generalized Sylvester equation based parametrization, three minimum norm robust pole assignment problems for descriptor systems are formulated as unconstrained minimization problems for suitably chosen cost functions. The derived explicit expressions of the gradients of the cost functions allow the efficient solution of the minimization problems by using powerful gradient search based minimization techniques. We also discuss how requirements for a particular Jordan structure of the closed-loop state matrix or for partial pole assignment can be accomodated with proposed approach
Controllable forms for stabilising pole assignment design of generalised bilinear systems
No full textBilinear structures are able to represent nonlinear phenomena more accurately than linear models, and thereby help to extend the range of satisfactory control performance. However, closed loop characteristics are typically designed by simulation and stability is not guaranteed. In this reported work, it is shown how bilinear systems are a special case of the more general state dependent parameter (SDP) model, which can subsequently be utilised to design stabilising feedback controllers using a special form of nonlinear pole assignment. To establish the link, however, an important generalisation of the SDP pole assignment method is developed
Robust Pole Assignment via Sylvester Equation Based State Feedback Parametrization
No full textBy using a Sylvester equation based parametrization, the minimum norm robust pole assignment problem for linear time-invariant systems is formulated as an unconstrained minimization problem for a suitably chosen cost function. The derived explicit expression of the gradient of the cost function allows the efficient solution of the minimization problem by using powerful gradient search based minimization techniques. We also discuss how requirements for a particular Jordan structure of the closed-loop state matrix or for partial pole asignment can be accomodated with the proposed approach
Boat
No full textThe launch 'Sea Dog' unloading provisions after the wet - replacement supplies which the shipwrecked boat Chas Pole was on failed to deliver. Daly River Crossing.Jones, Peter.Date:194
Man with pig
No full textMr Turnoff, Evans Deakins (Engineer). Chas Pole was to act as his guide when they arrived at the Daly. The pig was a pet of some Aborigines who turned up in a large canoe.Jones, Peter.Date:194
A numerically reliable approach to robust pole assignment for descriptor systems
No full textWe propose a general, numerically reliable computational approach to solve the pole and eigenstructure assignment problem for descriptor systems. In the multi-input case, the proposed approach addresses the intrinsic non-uniqueness of the pole assignment problem solution by simultaneously minimizing the sensitivity of the feedback gain and of closed-loop eigenvalues. For this purpose, a minimum norm robust pole assignment problem is formulated and solved as an unconstrained minimization problem for a suitably chosen cost function. By using a generalized Sylvester equation-based parameterization, an explicit expression of the gradient of the cost function is derived to allow the efficient solution of the minimization problem by using powerful gradient search-based minimization techniques
Boat
No full textThe supply lugger for Daly River Police and Mission which hit a reef on the mainland side of Peron Island north. After a lot of skill on behalf of the skipper, the boat was beached on the only site of sandy beach on the mainland, not far from the mouth of the Daly. Chas Pole was one of the crew.Jones, Peter.Date:194
Group
No full textGroup of men. Back row: Swanson brothers. Front row L-R: young clerk from the post office or bank; Mr Harris, contactor; the Count; unidentified; Bob Buck. Chas Pole was doing odd jobs for both Mr Harris and Mr O'Shea during the wet. The Swansons took over the railway hotel shortly after.Jones, Peter.Date:194
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