NET POWER PRODUCTION AND PERFORMANCE AT DIFFERENT STROKE RATES

Economy in propelling a rowing boat is important in competitive rowing as, for a given power output from the rower, the more effective the rower is the faster the boat will go for a given power output. Velocity cost (average power required to propel the boat for each m s-1) is a measure that will discriminate between effective and ineffective rowers. The purpose of this study was to measure a number of capacity and technique variables (including velocity cost) during on-water rowing of paired boats at 20, 24, 28 and 30 str min-1. Among the four pairs of rowers tested clear differences were found at particular boat velocities in the velocity cost. A number of technique variables were identified as possible causes of these differences. A linear regression analysis included six of these parameters which together explained 97% of the variability in velocity cos

INTRA-STROKE BOAT ORIENTATION DURING SINGLE SCULLING

It has been established that the amount of yaw, pitch and roll induced in the boat by a sculler, will affect the efficiency of boat propulsion. Therefore, the purpose of this study was to analyse the orientation of a rowing boat (Single Scull) in three dimensions and to relate the results to the rowing style of the sculler. The study will examine the relationship between the boat orientation, the seat and the hand position. In rowing, the movement of the seat and the rowers’ body mass influences the pitch of the boat. The roll and yaw of the boat is dependent on the skill level of the athlete and weather conditions. This relationship is a useful indicator for training and performance assessment of athletes

THE RELATIONSHIP BETWEEN SEAT MOVEMENT AND BOAT ACCELERATION DURING SCULLING

Fluctuations in boat velocity during rowing should be minimised in achieving the shortest possible time for the 2000m race. The aim of this study was to examine the relationship between the movement of the major body segments of a rower and the acceleration of the boat. Seat position, seat velocity, boat acceleration, and oar angle were measured for one rower for three stroke rates for at least ten consecutive strokes. Seat position was used to approximate the position of the centre of mass of the trunk and thighs. Maximum seat velocity increased with stroke rate. Differences in acceleration of the boat could be related to changes in the slope of the seat velocity curve

Optimization of energy intensity of machine tools for cutting operations

In this paper, solutions for optimizing energy intensity of machine tools were presented. In the introduction, the concept of energy intensity was explained, along with energy consumption of machining industry and main factors affecting it. In the main part of this work energy consumption of machine tools was discussed on account of their construction features, type of machining processes and energy intensity of ancillary processes and devices. Possibilites for improvements in energy intensity of machine tools a t three product life cycle stages (design, manufacturing and operation) were presented and discussed.W pracy przedstawiono rozwiązania optymalizujące energochłonność obrabiarek skrawających. We wstępie omówione zostało pojęcie energochłonności, zużycie energii przez przemysł wytwórczy oraz wpływające na nie czynniki. W głównej części pracy opisano zużycie energii elektrycznej przez obrabiarkę ze względu na jej cechy konstrukcyjne, rodzaj prowadzonego procesu obróbkowego, a także energochłonność procesów oraz urządzeń pomocniczych. Rozpatrywano również możliwości poprawy energochłonności w trzech fazach cyklu życia obrabiarki (projektowanie, wytwarzanie, eksploatacja)