Swimming turn performance: the distinguishing factor in 1500 m world championship freestyle races?

Objective Turn sections represent the second largest part of total race time in 1500 m freestyle races and may substantially affect race results. Therefore, the aim of the study was to investigate individual race strategies and compare the effect of start, swim, and turn performances between short-course and long-course races. Video footages were collected from all 16 male finalists at the 2018 short and 2019 long-course World swimming championships (age 23.06 ± 2.3 years, FINA points 941 ± 42) for subsequently analysis of start, turn, and swim performance. Results The larger number of turns in short-course races resulted in significantly faster race times (p = 0.004), but slower mean turn times compared to long-course races (p < 0.001). Total race velocity closely correlated with swim and turn but not start section velocity in short- (r ≥ 0.80, p ≤ 0.017) and long-course races (r ≥ 0.83, p ≤ 0.011). Analysis of individual race strategies showed that turn performance affected race results in 6 (75%) and 3 (37.5%) of the 8 world-best 1500 m swimmers in short-course and long-course races, respectively. Medal standing was improved for 1st, 3rd, and 4th ranked short- as well as 1st and 2nd ranked long-course finalist. Coaches, athletes, and performance analysts may carefully consider the importance of turn performance additionally to free-swimming skills.

Comparison of Starts and Turns between Individual and Relay Swimming Races

The present study investigated swimmers’ performances on the starting and turning segments between individual and relay races. A total number of 72 race performances of the same swimmers in both relay 4 × 100 m finals (freestyle, medley, and mixed freestyle) and individual 100 m finals or semi-finals (butterfly, breaststroke, and freestyle) from the LEN European Swimming Championships were compared with repeated measures MANOVA. Swimmers performed 5–7% faster starts in the relay than in the corresponding individual events, despite no differences in the flight phase and a lower performance (shorter distances and slower velocities) on the underwater start section. The 15 m turn times were slower in the butterfly relay races although no specific differences in the underwater parameters were observed. These results suggest that specific training of the starting and turning segments should be performed under relay conditions to optimise pacing and performance in the underwater sections.

Swimming turn performance: the distinguishing factor in 1500m World championship freestyle races?

Objective Turn sections represent the second largest part of total race time in 1500 m freestyle races and may substantially affect race results. Therefore, the aim of the study was to investigate individual race strategies and compare the effect of start, swim, and turn performances between short-course and long-course races. Video footages were collected from all male finalists at the 2018 short- (n = 8, age 22.8 ± 2.4 years, FINA points 953 ± 27) and 2019 long-course World swimming championships (n = 8, age 23.3 ± 2.2 years, FINA points 951 ± 23) for subsequently analysis of start, turn, and swim performance. Results The larger number of turns in short-course races resulted in significantly faster race times (p < 0.001), but slower mean turn times compared to long-course races (p < 0.001). Total race time closely correlated with swim and turn but not start section time in short- (r ≥ 0.76, p ≤ 0.030) and long-course races (r ≥ 0.96, p < 0.001). Analysis of individual race strategies showed that turn performance affected race results in 9 of the 16 world-best 1500 m swimmers and improved medal standing of 1st, 3rd, and 4th ranked short- as well as 1st and 2nd ranked long-course finalist. Coaches, athletes, and performance analysts may carefully consider the importance of turn performance additionally to free-swimming skills.

Design and Implementation of the Stone Elliptical Arc Contour Fitting Algorithm

Elliptical arcs have been widely used in stone contours, but the circular saw of the existing stone bridge cutting machine can only cut stone contours which compose of long lines and large radius arcs. The elliptical arc is often fitted by small line segments or small arc segments, and the circular saw cannot be used to process the stone elliptical arc contour. Therefore, a better choice of fitting the elliptical arc in the stone contour is the four-arc fitting algorithm. The traditional four-arc fitting ellipse algorithm can only fit the whole ellipse, in order to fit elliptical arcs, a new fitting algorithm of four-arc fitting elliptical arc is designed. Firstly, identify the stone contour and analyze the elliptical entities section from the DXF file, and divide the elliptical arc curve into several arcs according to the angular relationship. Then adopting the Chebyshev approximation theory of four-arc fitting ellipse, the preliminary fitting of the elliptical arc is performed, and re-fit the start section and end section of the elliptical arc curve, the elliptical arc fitting algorithm is designed. In addition, the maximum value of fitting error has been calculated. Finally, by using the Visual C++ as the developing software, the stone elliptical arc contour fitting algorithm and its processing trajectory simulation are realized. Testing results show that the fitting algorithm can meet the requirements of the circular saw cutting the stone elliptical arc contour.

Development and Evaluation of a Frequency Related Source Intensity Prediction Model of the Traffic Acoustic Noise

Two expressway sections including the south section of the beltway in Xian and the start section of the Xi'an-Lantian expressway were selected in this study. By monitoring the acoustic noise level at different frequencies and vehicle speeds, a frequency related source intensity prediction model of the traffic acoustic noise was developed. Experimental results show that the spectrum distribution varies greatly among different kind of vehicles. The noise source intensity produced by large vehicles mainly distribute in low-frequency area. Different from large vehicles, medium vehicles mainly produce medium or high frequency noise, especially when the vehicle's speed is above 60 km/h. When the vehicle's speed is below 60 km/h, the acoustic noise intensity produced by the medium vehicles is relatively weak. The accuracy of the source intensity prediction model is further proved by comparing the predicted data, determined data, and the data obtained in the literature under similar experimental conditions.

Trajectory Planning of Mobile Robots Using DNA Computing

DNA computers are attracting increasing attention as next-generation replacements for conventional electronic computers. Computation is realized using the chemical reaction of DNA. This paper presents optimal trajectory planning for mobile robots using DNA computing. The working area of a mobile robot is divided into many sections and the shortest trajectory avoiding obstacles in the work area is calculated by DNA computing. The location of obstacles is known in advance. In DNA computing, Watson-Crick pairing is used to find this trajectory. DNA sequences representing locations of obstacles are removed in this process. The shortest DNA molecule that begins with the start section and terminates with the goal section represents the shortest trajectory avoiding obstacles in the robot’s work area. The proposed algorithm is especially effective with a DNA molecular computer.

Analysis of the Bobsled and Men’s Luge Events at the XVII Olympic Winter Games in Lillehammer

Performance in bobsled and luge events is influenced by several environmental, material/equipment, and team-related factors. This study concentrated on the influences of equipment and athlete on overall performance and compared the luge, 2-man bobsled, and 4-man bobsled competitions at the 1994 Lillehammer Winter Olympic Games. Start time and overall acceleration in the analyzed straight section showed significant correlations with the final time. It was concluded that for the top teams in bobsled and luge, fast start time and high speed at the end of the start section were prerequisites for an excellent overall performance. Driving capacities in the most difficult sections of the track were more statistically important among the top 15 competitors, especially in the luge. The influence of the runners could not be identified in either bobsled or luge competitions.

Sodium Amylobarbitone and Responses to Nonreward*

Three experiments are reported testing two alternative hypotheses concerning the behavioural effects of sodium amylobarbitone (SA): (1) that it blocks the after-effect of nonreward; (2) that it blocks conditioned frustration, elicited by stimuli associated with nonreward. In support of (2) Experiment I showed that SA given in acquisition abolished the partial reinforcement extinction effect (PREE) when rats were run at one trial a day in an alley for food reward on a continuous (CRF) or partial (PRF) reinforcement schedule. Experiment II showed that, in the goal section, the effect of the drug on the PREE was due to its presence during acquisition and was not due to state dependency; but the effect of the drug in the start section was consistent with state dependency of the PREE. In Experiment III, in opposition to (1) and again in support of (2), SA given to rats trained to show patterned running for water reward on a single alternation schedule blocked patterning by increasing running speeds on nonreward trials, not by decreasing running speeds on rewarded trials.