acceleration zone
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Author(s):  
Sarah da Glória Teles Bredt ◽  
Daniel de Souza Camargo ◽  
Bernardo Vidigal Borges Mortoza ◽  
André Gustavo Pereira de Andrade ◽  
Leopoldo Augusto Paolucci ◽  
...  

Small-sided games are used to improve tactical-technical and physical performances in team sports. This study compared the physical, physiological, and tactical-technical responses during 3 versus 3 basketball small-sided games performed in full and half-court: numerical equality (3 vs. 3), numerical superiority (4 vs. 3), and with a non-scorer floater (3 vs. 3  +  1). A total of 45 U-14 and U-15 male athletes participated in the study. They were divided into three-player teams and played one 4-minute bout of each small-sided game type. Heart rate and the time spent in four acceleration zones (0.0–0.5, 0.5–1.0, 1.0–1.5, and 1.5–2.0 g) were recorded using heart rate monitors and triaxial accelerometers. Small-sided games were filmed for the analysis of tactical-technical behavior. Results showed a higher frequency of space creation without the ball, and a mean number of passes per offense in the formats 4 versus 3 and 3 versus 3  +  1, and a lower frequency of space creation with the ball dribbled in 3 versus 3  +  1 compared with 3 versus 3. Physical and physiological responses were higher in the full-court regardless of format and in numerical equality regardless of court area; only the time spent in the highest acceleration zone was higher in half-court small-sided games. We concluded that additional players increase group tactical actions and decrease physical and physiological responses in 3 versus 3 basketball small-sided games.


Author(s):  
K. Harish Kiri Sivakumar ◽  
Kannan Aravamudan

Abstract The importance of the axial catalyst holdup on the accurate prediction of reaction yields from Fluidized Catalytic Cracking Unit (FCCU) risers was explored in this study. The Kunii and Levenspiel model was incorporated in the FCCU riser simulations for predicting the solid holdup. Two approaches were compared – the popular one assuming Constant Holdup (CH) and the other incorporating Variable Holdup (VH) in the reaction kinetics models. Simulation predictions using these two approaches were fitted to the yield profiles obtained from industrial plant data reported in the literature. The kinetic parameter estimates, including frequency factors and coking parameters obtained from these two approaches, were quite similar, indicating insensitivity to catalyst holdup. However, the kinetic model incorporating VH expression could predict the plant conversion and yield to within ±10% error throughout the riser. In contrast, the CH model led to predictions that were rather erroneous (>±25%) at the riser bottom as the catalyst particle acceleration zone was neglected. Temperature, gas density, catalyst particle, and gas phase velocity profiles obtained from the VH approach were considerably different from those obtained using the CH approach. The VH approach showed that the slip factor, especially, was quite distinct as it reached a peak value before decaying exponentially. On the other hand, the CH model showed a monotonic increase in slip factor along the riser.


2021 ◽  
pp. 142-148
Author(s):  
Phillip M. Bellinger ◽  
Timothy Newans ◽  
Mitchell Whalen ◽  
Clare Minahan

Effective time-motion analysis can provide information directly applicable to the design of physical conditioning and testing programmes. The aim of the present study was to determine the external output of female beach volleyball players during tournament match-play and to assess the effect of competition level, margin of score differential and alterations of external output within matches. The external output profile of ten adult level (age 27 ± 3 y) and ten under 23 (‘U23’; age 19 ± 2 y) female beach volleyball players were determined using GPS technology (10 Hz) during 60 matches (n = 50 first and second sets and 20 third sets files) played during their respective Australian Beach Volleyball Championship tournaments. Comparisons between groups and the influence of contextual factors on the external output within matches were analysed using linear mixed models. Adult beach volleyball players covered a greater relative distance (i.e., m·min-1) in speed zone 2 (1.0-1.99 m·s-1; 42.0% of total relative distance) and zone 3 (≥2.0 m·s-1; 10.9% of total relative distance) compared to U23 players. Relative distance, mean acceleration/deceleration and the relative distance covered in acceleration zone 2 and deceleration zone 2 and 3 was greater in set 1 compared to set 2. Sets that were decided by smaller score margins (<6-point score differential) were comprised of a greater relative distance, peak speed, greater mean acceleration and deceleration output and a greater relative distance in speed zone 1 and 3 compared to sets decided by larger score margins (>5-point score differential). The findings from this study suggest that there are contextual factors that influence the speed and acceleration/deceleration profile of female beach volleyball players such as tournament level, score margin and set-to-set variations that may have implications for the physiological and mechanical requirements of female players preparing for competition.


Retos ◽  
2020 ◽  
pp. 18-26
Author(s):  
Vitor Ayres Principe ◽  
Ignácio Antônio Seixas-da-Silva ◽  
Rodrigo Gomes de Souza Vale ◽  
Rodolfo De Alkmim Moreira Nunes

Abstract. This study aimed to determine the external load demands of elite Brazilian soccer players by position and playing time, using data from global positioning technology (GPS) at a data acquisition frequency of 10Hz from a Polar Team Pro. Twenty-three professional players from a top-flight Brazilian women's soccer team participated in the study. The women were 27.65 ± 4.66 years, 165.35 ± 5.82 cm and 60.91 ± 5.34 kg. Data were collected during two competitions disputed simultaneously, the The São Paulo State Championship and the Brazilian Championship A1 series of 2019. Nine variables related to the external locomotor demand performed by the players in the disputed matches were analyzed. The statistical procedures used were the two-way ANOVA with Bonferroni post hoc for data adjustment, and Cohen’s effect size (d), with a p-value < .05 adopted to demonstrate statistical significance. The significant differences in the variables total distance, walking distance, jogging distance, running distance, Sprinting distance, acceleration zone 1, acceleration zone 2, deceleration zone 1 and deceleration zone 2 were analyzed, and the results showed a decrease in the external locomotor demand of the loads during the matches played by these athletes. These results should be used to improve load control and adapt training practices in women's soccer teams.  Resumen. Este estudio tuvo como objetivo determinar el comportamiento de las demandas de carga externa de los jugadores de fútbol brasileños de élite por posición y tiempo de juego, utilizando datos de la tecnología de posicionamiento global (GPS) a una frecuencia de adquisición de datos de 10Hz de un Polar Team Pro. Veintitrés jugadoras profesionales de un equipo de fútbol femenino brasileño de primer nivel participaron en el estudio. Las mujeres tenían 27.65 ± 4.66 años, 165.35 ± 5.82 cm y 60.91 ± 5.34 kg. Los datos fueron recolectados durante dos competencias disputadas simultáneamente, el Campeonato del Estado de São Paulo y el Brasileño de la serie A1 de 2019. Se analizaron nueve variables relacionadas con la demanda externa de locomotoras realizadas por los jugadores en los partidos disputados. Los procedimientos estadísticos utilizados fueron el ANOVA de dos vías con Bonferroni post hoc para el ajuste de datos, y el tamaño del efecto de Cohen (d), con un valor de p < .05 adoptado para demostrar la significación estadística. Se analizaron las diferencias significativas en las variables distancia caminando, distancia de trote, distancia corriendo, distancia de sprint, zona de aceleración 1, zona de aceleración 2, zona de desaceleración 1 y zona de desaceleración 2, y los resultados mostraron una disminución en la demanda locomotora externa de las cargas durante los partidos jugados por estos Atletas. Estos resultados deberían usarse para mejorar el control de carga y adaptar las prácticas de entrenamiento en los equipos de fútbol femenino.


2020 ◽  
Vol 891 (1) ◽  
pp. 33 ◽  
Author(s):  
Shlomi Hillel ◽  
Ron Schreier ◽  
Noam Soker

Author(s):  
Вячеслав Сергеевич Долгих

The paper represents the analysis intended to optimize the fuselage nose section with regard to aircraft aerodynamics in the process of development of an unmanned transport aircraft (UTA). The article deals with provisions of high aerodynamic efficiency that cannot be achieved without proper selection of the shape and optimal fuselage parameters that determine mutual interference of aircraft components and units. When analyzing the flow improvement around the fuselage nose in flight, three fuselage versions were considered listed further: 1) a prototype for testing automatic flight control systems with participation of pilots; 2) a nose symmetrical relative to the fuselage rocket type cylinder axis; 3) a supposedly optimal variant based on the results of previous calculations. The aerodynamic characteristics of 3D fuselage models for positive integer Reynolds numbers (full-scale model) were calculated using the ANSYS software package. Three computational grids were built for these models in ANSYS ICEM CFD. The given version of the fuselage nose section intended for testing automatic flight control systems with participation of pilots initially has the greatest resistance among the considered variants. That is, first variant of the fuselage nose gives substantial braking zone as well as significant flow acceleration zone exists in place where fuselage is transformed into cylindrical part. The variant with the nose section symmetrical relative to the rocket type cylinder axis has smaller braking zone and less dispersed flow in place where fuselage is transformed into cylindrical part and, therefore, it has lower resistance in comparison with the first version. The fuselage execution developed on the basis of the results of previous calculations, despite the extensive acceleration zone at the junction of the nose to the cylindrical part, has shown the least resistance, respectively, and is the best of the considered variants. This is also confirmed by a comparison of streamlines over the nose surface. The streamlines are given for calculations at angle of attack of 8°; at this angle of attack, the difference in the coefficient Cx is clearly visible.


2019 ◽  
Vol 59 (2) ◽  
pp. 118-128
Author(s):  
Ladislava Doležajová ◽  
Tatiana Gallová ◽  
Anton Lednický

Summary Basketball is a complex team sport, which combines cyclic and acyclic motion structures consisting mainly of fast and dynamic moves with or without a ball. The puberty is characterized by considerable variability that may occur earlier (developmental acceleration, early maturing) or later (developmental retardation, late maturing): an example can be a 12-year-old girl whom biological age could range from 9.5 to 14.5 years. For this study we selected 6 girls-players from the whole team. Two players were according to the norms from the zone of developmental retardation (BioRet), two players whose decimal and biological age i.e. bone age was identical (DC = BV), and the other two were in the biological acceleration zone (BioAkc.). All players were 13-years old and competed in the U14 category. We have confirmed that there are great differences in biological age in a group of 13-years old girls – in our research it has shown almost four years difference. We did not confirm the author's conclusions that biologically accelerated individuals achieved better results than the retarded ones in the speed and strength tests.


2019 ◽  
Vol 631 ◽  
pp. A44 ◽  
Author(s):  
T. Giannini ◽  
B. Nisini ◽  
S. Antoniucci ◽  
K. Biazzo ◽  
J. Alcalá ◽  
...  

Context. The mechanism for jet formation in the disks of T Tauri stars remains poorly understood. Observational benchmarks to launching models can be provided by tracing the physical properties of the kinematic components of the wind and jet in the inner 100 au of the disk surface. Aims. In the framework of the GIARPS High-resolution Observations of T Tauri stars (GHOsT) project, we aim to perform a multi-line analysis of the velocity components of the gas in the jet acceleration zone. Methods. We analyzed the GIARPS-TNG spectra of six objects in the Taurus-Auriga complex (RY Tau, DG Tau, DL Tau, HN Tau, DO Tau, RW Aur A). Thanks to the combined high-spectral resolution (ℜ = 5°0 000−115 000) and wide spectral coverage (~400−2400 nm) we observed several O 0, S +, N 0, N +, and Fe + forbidden lines spanning a large range of excitation and ionization conditions. In four objects (DG Tau, HN Tau, DO Tau, RW Aur A), temperature (Te), electron and total density (ne, nH), and fractional ionization (xe) were derived as a function of velocity through an excitation and ionization model. The abundance of gaseous iron, X(Fe), a probe of the dust content in the jet, was derived in selected velocity channels. Results. The physical parameters vary smoothly with velocity, suggesting a common origin for the different kinematic components. In DG Tau and HN Tau, Te, xe, and X(Fe) increase with velocity (roughly from 6000 K, 0.05, 10%X(Fe)⊙ to 15 000 K, 0.6, 90%X(Fe)⊙). This trend is in agreement with disk–wind models in which the jet is launched from regions of the disk at different radii. In DO Tau and RW Aur A, we infer xe < 0.1, nH ~ 106−7 cm−3, and X(Fe) ≲ X(Fe)⊙ at all velocities. These findings are tentatively explained by the formation of these jets from dense regions inside the inner, gaseous disk, or as a consequence of their high degree of collimation.


2019 ◽  
Vol 627 ◽  
pp. A89 ◽  
Author(s):  
B. Boccardi ◽  
G. Migliori ◽  
P. Grandi ◽  
E. Torresi ◽  
F. Mertens ◽  
...  

Context.In March 2018, the detection by VERITAS of very-high-energy emission (VHE >  100 GeV) from 3C 264 was reported. This is the sixth, and second most distant, radio galaxy ever detected in the TeV regime.Aims.In this article we present a radio and X-ray analysis of the jet in 3C 264. We determine the main physical parameters of the parsec-scale flow and explore the implications of the inferred kinematic structure for radiative models of thisγ-ray emitting jet.Methods.The radio data set is comprised of VLBI observations at 15 GHz from the MOJAVE program, and covers a time period of about two years. Through a segmented wavelet decomposition method (WISE code), we estimated the apparent displacement of individual plasma features; we then performed a pixel-based analysis of the stacked image to determine the jet shape. The X-ray data set includes all available observations from theChandra, XMM, andSwiftsatellites, and is used, together with archival data in the other bands, to build the spectral energy distribution (SED).Results.Proper motion is mostly detected along the edges of the flow, which appears strongly limb brightened. The apparent speeds increase as a function of distance from the core up to a maximum of ∼11.5 c. This constrains the jet viewing angle to assume relatively small values (θ ≲ 10°). In the acceleration region, extending up to a de-projected distance of ∼4.8 × 104Schwarzschild radii (∼11 pc), the jet is collimating (r ∝ z0.40 ± 0.04), as predicted for a magnetically-driven plasma flow. By assuming that the core region is indeed magnetically dominated (UB/Ue >  1), the SED and the jet power can be well reproduced in the framework of leptonic models, provided that the high-energy component is associated to a second emitting region. The possibility that this region is located at the end of the acceleration zone, either in the jet layer or in the spine, is explored in the modeling.


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