ASSESSMENT OF NORMALIZED DISTANCE PER STROKE AND SWIMMING EFFICIENCY IN THE 2000 OLYMPIC GAMES

Stroke length has been viewed as an important determinant in swimming speed and performance. However, recent studies of elite level athletes have shown that stroke length (SL) typically does not correlate with swimming speed in elite athletes. These studies have focused on absolute stroke length and have not taken into consideration the size of the athletes. The noted lack of correlation may be due to the variability introduced by differences in athlete size. This study looks at athlete SL normalized to body height and introduces the concept of using normalized SL (NSL) as a measure of efficiency. Pearson correlation coefficients were computed to relate NSL to swimming speed and analyses of variance were conducted to examine differences between finalists and semifinalists at the 2000 Olympic Games. Significant findings and their relationship to performance are discussed

ANALYSIS OF A SWIMMERS HAND AND ARM IN STEADY FLOW CONDITIONS USING COMPUTATIONAL FLUID DYNAMICS

As an alternative to the experimental determination of the hand and arm propulsive forces generated by swimmers, the numerical technique of computational fluid dynamics (CFD) has been used to calculate the steady flow around a swimmer's hand and arm at various angles of attack. Significant boundary layer separation was seen, ruling out the use of Bernoulli's equation to mathematically describe the lift generated by a swimmer. Computation of 3D lift is necessary to describe the propulsion generated by the arm at all angles of attack and the hand near angles of attack of 90 degrees. Force coefficients computed for the hand and arm compared well with steady-state coefficients determined experimentally. Such comparisons validate the chosen CFD techniques, and are an important first step toward the use of CFD for determining swimming hydrodynamic forces in more realistic unsteady flow conditions

CFD ANALYSIS OF A SWIMMER'S ARM AND HAND, ACCELERATION AND DECELERATION

The numerical technique of computational fluid dynamics (CFD) has been used to determine the effect of arm and hand acceleration and deceleration on the propulsive forces generated by swimmers. Relationships developed to predict hand and arm forces as a function of both velocity and acceleration show these forces can be significantly different from those calculated using the quasi-steady approach. Simple equations that provide a correction factor to forces calculated using the quasi-steady approach are provided. The analyses showed that drag and axial forces (along length of the arm) were affected more by unsteady flow than were the lift forces. Also, arm forces were affected more than were hand forces. And finally, maximum propulsion was obtained from the hand when it faced directly backwards towards the feet, even though the stroke itself may be moving diagonally

Deformation and Fracture of MnTe and MnSe-MnTe Solid Solutions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65773/1/j.1151-2916.1970.tb12074.x.pd

EFFECTS OF HANDLE AND BLOCK CONFIGURATION ON SWIM START PERFORMANCE

The purpose of this study was to quantify differences in swimming track start performances using side handle and front handle grip techniques and using an inclined platform at the rear of the starting platform. An instrumented starting block system was designed to allow front grip and side grip starting techniques and inclusion of a rear incline. Thirty male and 20 female junior elite swimmers completed three starts in each of four start block configurations: (1) Flat (traditional) block, front handle grip; (2) Flat (traditional) block, side handle grip; (3) Incline (new) block, front handle grip; (4) Incline (new) block, side handle grip. Force and video data were used to quantify parameters related to starting performance. Results indicated that use of side handles had a substantial impact on start performance while the effects of the rear incline were less pronounced. Compared to using a front grip technique, use of the side handles increased horizontal velocity at takeoff up to 18%, resulted in a more horizontal takeoff angle by up to 2°, increased contribution to horizontal impulse from arms up to 12%, increased peak horizontal power up to 28%, decreased time to 6 m by 4% and increased velocity at 6 m by 2.5%. These advantages were achieved at a cost of an 8% increase in propulsion time. Based on this study, we recommend swimmers develop familiarity with the use of side handles when performing a track start and to use this technique if handles are available on a starting block

MODELLING COMPETITIVE SWIMMING IN DIFFERENT STROKES AND DISTANCES UPON REGRESSION ANALYSIS: A STUDY OF THE FEMALE PARTICIPANTS OF SYDNEY 2000 OLYMPIC GAMES

The purpose of the study was to obtain the slope and y-intercept of the regression between race component times and race time for a group of top level female swimmers (the best 16 times) in the 2000 Sydney Olympic Games. All the 50, 100 and 200 rn events were analyzed in this study. A multi-camera video recording system (7 cameras) was located on the catwalk 18m above the center lanes of the pool. The regression and correlation coefficients were significant in 78% of the races analyzed, excluded stroke frequency, stroke length and stroke index. The quality of the swimmers analyzed enabled the calculation of the recommended times in each phase in relation to race time. This information may allow top level swimmers to train specifically in their weakest race component

RELATIONSHIPS BETWEEN STROKE EFFICIENCY MEASURES AND FREESTYLE SWIMMING PERFORMANCE: AN ANALYSIS OF FREESTYLE SWIMMING EVENTS AT THE SYDNEY 2000 OLYMPICS

The purpose of this study was to investigate the relationships between measures of stroke efficiency and performance in the freestyle swimming events of the Sydney 2000 Olympics. Measures of variables describing swimming performance were determined from overhead video of the races according to the Australian Institute of Sport protocol. All performances by swimmers in the finals and semifinals were included in the analysis for the 50, 100 and 200 m events and performances for finalists only were analyzed for longer events. A within subjects, repeated measures linear-regression analysis was used to determine relationships. The lack of relationships determined for SI with either swim velocity or performance time in the longer events indicated that the SI was not a good indicator of swimming efficiency for women's freestyle events. In contrast, a predominance of these relationships in the longer events indicated that the SI was possibly an indicator of swimming efficiency for men's freestyle events. SL was not found to be a good predictor of swimming speed or an indicator of swimming efficiency for the freestyle events

The LiNiO2_{2} Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties Part II. Morphology

A better understanding of the cathode active material (CAM) plays a crucial role in the improvement of lithium-ion batteries. We have previously reported the structural properties of the model cathode material LiNiO$_{2}$ (LNO) in dependence of its calcination conditions and found that the deviation from the ideal stoichiometry in LiNiO2 (Ni excess) shows no correlation to the 1st cycle capacity loss. Rather, the morphology of LNO appears to be decisive. As CAM secondary agglomerates fracture during battery operation, the surface area in contact with the electrolyte changes during cycle life. Thus, particle morphology and especially the primary particle size become critical and are analyzed in detail in this report for LNO, using an automated SEM image segmentation method. It is shown that the accessible surface area of the pristine CAM powder measured by physisorption is close to the secondary particle geometric surface area. The interface area between CAM and electrolyte is measured by an in situ capacitance method and approaches a value proportional to the estimated primary particle surface area determined by SEM image analysis after just a few cycles. This interface area is identified to be the governing factor determining the 1st cycle capacity loss and long-term cycling behavior