Inledning: Bandy är en vinterlagsport som innehåller både fysiska och tekniska krav. Till författarnas kännedom finns begränsat med vetenskaplig forskning om bandyspelares fysiska krav under match. Syfte: Syftet med denna studie var att beskriva manliga elitbandyspelares rörelseprofiler utifrån total distans, maximal hastighet, medelhastighet, speltid, hastighetszoner och acceleration under matchsituation mellan olika spelarpositioner. Metod: Datainsamlingen utfördes med tio hertz GPS-enheter på ett elitserielag i bandy från mellersta Sverige under säsongen 2014/15. Sex till åtta manliga elitbandyspelare studerades under elva matchtillfällen. Data analyserades både deskriptivt och genom envägs variansanalys (ANOVA) för att se signifikanta skillnader mellan spelarpositioner. Resultat: Mätningarna visade att spelarpositionen halv uppnådde den längsta totala distansen. Anfall hade den högsta medelhastigheten och utförde flest antal accelerationer per spelad minut. Spelarpositionen libero, back och halv hade den högsta speltiden och det var signifikanta skillnader till mittfält och anfall. Libero och back hade i de två långsammaste hastighetszonerna högst procent av total distans och utförde flest antal aktioner. Halv, mittfält och anfall hade i de två snabbaste hastighetszonerna högst procent av total distans och utförde flest antal aktioner. Slutsats: Detta indikerade att halv, mittfält och anfall hade likande resultat och hade de största fysiska kraven under match jämfört mot libero och back. / Introduction: Bandy is a team winter sport that contains both physical and technical demands. To the authors knowledge there is a limited scientific research on bandy player’s physical demands during the matches. The Aim: The aim of this study was to describe the male elite bandy players movement profiles based on total distance, maximum velocity, mean velocity, game time, velocity zones and acceleration during the match between different playing positions. Method: Data was collected with ten hertz GPS-units in an elite league team in bandy from middle of Sweden during the season 2014/15. Six to eight male elite bandy players were examined during eleven matches. Data were analyzed both descriptive and with one-way analysis of variance (ANOVA) to see significant differences between playing positions. Results: The measurements showed that the playing position half preformed the longest total distance. Forward preformed the highest mean velocity and performed the most number of accelerations per played minute. The playing positions libero, back and half had the highest game time and had significant differences to midfield and forward. Libero and back had the highest percent of the total distance, and performed the highest number of efforts in the two slowest velocity zones. Half, midfield and forward had the highest percent of the total distance and performed the highest number of efforts in the two fastest velocity zones. Conclusion: This indicated that half, midfield and forward had similar results and had the highest physical demands during the game compared to libero and back.

Laboratory experiments concerning stage-discharge, flow resistance, bedforms, sediment transport and flow structures have been carried out in a meandering channel with simulated non-vegetated and vegetated floodplains for overbank flow. The effect of placing solid blocks in different arrangements as a model of rigid, unsubmerged floodplain vegetation on a floodplain adjacent to a meandering channel is considered. The aim was to investigate how density and arrangements of floodplain vegetation influence stage-discharge, flow resistance, sediment transport and flow behaviours. Stage-discharge curves, Manning's n and drag force FD are determined over 165 test runs. The results from the laboratory model tests show that the placing of solid blocks along some part of the bend sections has a significant effect on stage-discharge characteristics. The change in stage-discharge by the blocks is compared using different arrangements, including the non-vegetated floodplains case. The experimental results show that the presence of energy losses due to momentum exchange between the main channel and the floodplain as well as the different densities of the blocks on a floodplain induce additional flow resistance to the main channel flow, particularly for shallow overbank flows. In general, the results show that the density and arrangement of blocks on the floodplains are very important for stage-discharge determination and, in some cases, for sediment transport rates, especially for a mobile main channel. Also, the correction parameter, a is introduced in order to understand the effects of blocks and bedforms on the force balance equation. By applied the correction factor c; a stagedischarge rating curve can be estimated when the avalue is calibrated well. Telemac 2D and 3D were applied to predict mean velocity, secondary flow and turbulent kinetic energy. Telemac computations for non-vegetated and vegetated floodplain cases in a meandering channel generally give reasonably good predictions when compared with the measured data for both velocity and boundary shear stress in the main channel. Detailed analyses of the. predicted flow variables were therefore carried out in order to understand mean flow mechanisms and secondary flow structures in compound meandering channels. The non-vegetated and two different cases of vegetated floodplain for different relative depths were considered. For the arrangement on a non-vegetated floodplain shows how the shearing of the main channel flow as the floodplain flow plunges into and over the main channel influences the mean and turbulent flow structures, particularly in the cross-over region. While applying vegetated floodplain along a cross-over section confirmed that the minimum/reduction shearing of the main channel flow by the floodplain flow plunging into and over the main channel is observed from the cross-sectional distributions of the streamwise velocity (U), lateral velocity (V), and secondary flow vectors. In addition to that, the vegetated floödplain along the apex bend region shows a small velocity gradient within the bend apex region. However, strong secondary flow in the cross-over section suggested that the flow interaction was quite similar to the non vegetation case in the cross-over section region.

No description available.

This dissertation presents results from a thorough study of the tip-gap turbulent flow structure in a low-speed linear compressor cascade wind tunnel at Virginia Tech that includes a moving belt system to simulate the relative motion between the tip and the casing. The endwall pressure measurements and the surface oil flow visualizations were made on a stationary endwall to obtain the flow features and to determine the measurement profiles of interest. A custom-made miniature 3-orthogonal-velocity-component fiber-optic laser-Doppler velocimetry (LDV) system was used to measure all three components of velocity within a 50 mm spherical measurement volume within the gap between the endwall and the blade tip, mainly for the stationary wall with 1.65% and 3.30% tip gaps as well as some initial experiments for the moving wall. Since all of the vorticity in a flow originates from the surfaces under the action of strong pressure gradient, it was very important to measure the nearest-wall flow on the endwall and around the blade tip. The surface skin friction velocity was measured by using viscous sublayer velocity profiles, which verified the presence of an intense lateral shear layer that was observed from surface oil flow visualizations. All second- and third-order turbulence quantities were measured to provide detailed data for any parallel CFD efforts. The most complete data sets were acquired for 1.65% and 3.30% tip gap/chord ratios in a low-speed linear compressor cascade. This study found that tip gap flows are complex pressure-driven, unsteady three-dimensional turbulent flows. The crossflow velocity normal to the blade chord is nearly uniform in the mid tip-gap and changes substantially from the pressure to suction side. The crossflow velocity relies on the local tip pressure loading that is different from the mid-span pressure loading because of tip leakage vortex influence. The tip gap flow is highly skewed three-dimensional flow throughout the full gap. Normalized circulation within the tip gap is independent of the gap size. The tip gap flow interacts with the primary flow, separates from the endwall, and rolls up on the suction side to form the tip leakage vortex. The tip leakage vortex is unsteady from the observation of the TKE transport vector and oil flow visualizations. The reattachment of tip separation vortex on the pressure side strongly depends on the blade thickness-to-gap height ratio after the origin of tip leakage vortex but is weakly related to it before the origin of tip leakage vortex for a moderate tip gap. Other than the nearest endwall and blade tip regions, the TKE does not vary much in tip gap. The tip leakage vortex produces high turbulence intensities. The tip gap flow correlations of streamwise and wall normal velocity fluctuations decrease significantly from the leading edge to the trailing edge of the blade due to flow skewing. The tip gap flow is a strongly anisotropic turbulent flow. Rapid distortion ideas can not apply to it. A turbulence model based on stress transport equations and experimental data is necessary to reflect the tip gap flow physics. For the moving endwall, relative motion skews the inner region flow and is decorrelated with the outer layer flow. Hence, the TKE and correlations of streamwise and wall normal velocity fluctuations decrease. / Ph. D.

No description available.