scholarly journals Truncated Estimation of Skating Force-Velocity Profiling When Using High-Speed Video-Based Methods Compared to Radar-Derived Processing

2021 ◽  
Vol 9 ◽  
Author(s):  
Jerome Perez ◽  
Gaël Guilhem ◽  
Franck Brocherie
Keyword(s):  
High Speed ◽  
Ice Hockey ◽  
Time Shift ◽  
Maximal Velocity ◽  
High Speed Video ◽  
Lower Accuracy ◽  
Force Velocity ◽  
Linear Slope ◽  
Mean Differences ◽  
The Cost

This study aimed to compare the force-velocity mechanical variables derived from high-speed video- and radar-based method during forward skating sprint in ice hockey. Thirteen elite female ice hockey players performed two 40-m forward skating sprints to determine, in the horizontal plane, maximal velocity reached (Vmax), relative maximal theoretical force (F0), maximal theoretical velocity (V0), relative maximal power (Pmax), linear slope of the force-velocity relationship (FV slope), maximal value of the ratio of force (RFmax) and index of force application technique (Drf). Two different high-speed video-based methods adding a time shift (ST-TS) or not (ST) were used and independently compared to the radar-derived method. ST and ST-TS showed significant mean differences (all p < 0.002) compared to radar-derived processing for all variables except for V0 (p = 0.26) and Vmax (p = 0.13) inferred from ST. In reference to radar-derived variables, ST-TS significantly induced larger lower values compared to radar of the main forward skating sprint determinants (Pmax, F0, RFmax and Drf) and moderate-to-large overestimation for velocity variables (V0 and Vmax). Correlations between ST or ST-TS and radar-derived methods ranged from trivial for velocity variables to very large for force and power variables. Consequently, practitioners must be aware that using such high-speed video-based methods would permit to determine mechanical variables at the cost of much lower accuracy and reliability than the radar-derived method.

Force–Velocity–Power Profile in High-Elite Boulder, Lead, and Speed Climber Competitors

2020 ◽  
Vol 15 (7) ◽  
pp. 1012-1018
Author(s):  
Guillaume Levernier ◽  
Pierre Samozino ◽  
Guillaume Laffaye
Keyword(s):  
External Force ◽  
Coefficient Of Variation ◽  
High Speed ◽  
Intraclass Correlation ◽  
Force Production ◽  
Maximal Velocity ◽  
Mean Power ◽  
Power Profile ◽  
Force Velocity ◽  
The Difference

Purpose: To compare the force-production capacities among boulderers, lead climbers, and speed climbers during a pull-up test using a force–velocity–power profile. Methods: In total, 24 high-elite climbers (11 boulderers, 8 lead climbers, and 5 speed climbers) did 2 pull-ups at different percentages of their body mass (0%, 30%, 45%, 60%, and 70%). Force–velocity–power profile analyses were performed with the use of an accelerometer for each load. The intraclass correlation and coefficients of variation were calculated. A 1-way analysis of variance was performed with a Tukey post hoc test to assess the difference between the groups. Results: Regarding force, the coefficient of variation ranged from 1.00% to 6.18% and the intraclass correlation ranged from .98 to .99. For velocity, the coefficient of variation ranged from 2.75% to 6.62% and the intraclass correlation ranged from .84 to .95. The linear regression slope showed R2 to be between .93 and .99, confirming the high quality of the linear relationship between velocity and the external force produced during a pull-up. Boulderers presented significantly higher (P < .05) maximal power (+22.30% and +26.29%), mean power for the pull-up at body weight (+23.49% and +25.35%), and theoretical maximal velocity at zero force (+23.92% and +21.53%) than lead and speed climbers and a more significant curve increase (+35.21% compared with lead climbers). Conclusions: The reliability of the method was shown to be high. Moreover, boulderers were able to develop an important external force and had the capacity to maintain high speed when force production increased.

ANALISA PERBANDINGAN DALAM RANGKA PEMILIHAN BEBERAPA IP UPSTREAM PROVIDER DI PT. INDOSAT

2018 ◽  
Vol 4 (1) ◽  
pp. 57
Author(s):  
Yuli Anwar ◽  
Dahlar .
Keyword(s):  
Business Strategy ◽  
High Speed ◽  
Human Life ◽  
Sustainable Growth ◽  
The Internet ◽  
Network Service Provider ◽  
High Speed Data ◽  
Telecommunications Services ◽  
The Cost ◽  
Internet Network

Abstract. One of the advances in information technology that now has changed the outlook and human life, business process and business strategy of an institution is the internet. The internet is a very large networks that connected to computers and serves throughout the world in one centralized network. With the internet we can access data and information anytime and anywhere.    As one provider of high-speed data communications services and the pioneer of the internet network service provider in Indonesia that provides integrated services, as well as one of the pioneer development of internet services that provide extensive services in the building and apply it throughout Indonesia. Indosat ready to seize opportunities for sustainable growth of business spectrum are still sprawling Indonesia.    Therefore, Indosat continues to focus on the development of increased efforts to provide the best service for customers of Indosat. Indosat will continue to develop and expand network coverage and a larger investment that the company will achieve excellence in the field of integrated telecommunications services.    Ranking by region of the IP Providers can be seen by grouping IP Providers, and management over IP Providers prefer to choose providers based on where it orginates as an example for the region of the U.S if it will be preferred providers that come from U.S. providers.With the commencement of the internet network optimization start early in 2008 with the selection of the appropriate IP Upstream Provider criteria, it is up to date according to data obtained from Indosat, seen any significant changes to the cost of purchasing capacity of the IP Upstream.    Based on the data obtained that until Q3 or September 2008, the number of IP Upstream Providers that previously there were 20 to 10 IP Upstream Provider, IP Transit Price total decrease of 11% to the price of IP Transit Price / Mbps there is a decrease of 78%, while from the capacity bandwith an increase of 301% capacity from 2008.

APPLICATION OF THE EARLY DAMAGE DIAGNOSTICS TECHNIQUE TO EXAMINATION OF THE AVIATION PANEL

2019 ◽  
Vol 85 (6) ◽  
pp. 53-63 ◽  
Author(s):  
I. E. Vasil’ev ◽  
Yu. G. Matvienko ◽  
A. V. Pankov ◽  
A. G. Kalinin
Keyword(s):  
Acoustic Emission ◽  
Damage Detection ◽  
High Speed ◽  
Early Stage ◽  
Video Data ◽  
High Speed Video ◽  
Damage Diagnostics ◽  
Subsurface Defect ◽  
Sensitive Coating ◽  
Early Damage

The results of using early damage diagnostics technique (developed in the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) for detecting the latent damage of an aviation panel made of composite material upon bench tensile tests are presented. We have assessed the capabilities of the developed technique and software regarding damage detection at the early stage of panel loading in conditions of elastic strain of the material using brittle strain-sensitive coating and simultaneous crack detection in the coating with a high-speed video camera “Video-print” and acoustic emission system “A-Line 32D.” When revealing a subsurface defect (a notch of the middle stringer) of the aviation panel, the general concept of damage detection at the early stage of loading in conditions of elastic behavior of the material was also tested in the course of the experiment, as well as the software specially developed for cluster analysis and classification of detected location pulses along with the equipment and software for simultaneous recording of video data flows and arrays of acoustic emission (AE) data. Synchronous recording of video images and AE pulses ensured precise control of the cracking process in the brittle strain-sensitive coating (tensocoating)at all stages of the experiment, whereas the use of structural-phenomenological approach kept track of the main trends in damage accumulation at different structural levels and identify the sources of their origin when classifying recorded AE data arrays. The combined use of oxide tensocoatings and high-speed video recording synchronized with the AE control system, provide the possibility of definite determination of the subsurface defect, reveal the maximum principal strains in the area of crack formation, quantify them and identify the main sources of AE signals upon monitoring the state of the aviation panel under loading P = 90 kN, which is about 12% of the critical load.

Design of Electrolytic Strengthening Machine for Cutting Edge of Cutter

2016 ◽  
Vol 693 ◽  
pp. 1585-1590
Author(s):  
Yi Zhuo Guo ◽  
Xian Guo Yan ◽  
Shu Juan Li ◽  
Hong Guo
Keyword(s):  
Service Life ◽  
Calculation Method ◽  
High Speed ◽  
High Speed Steel ◽  
Cutting Edge ◽  
The Cost ◽  
Electric Quantity

Many studies have proved the service life of cutter can be prolonged by electrolytic strengthening. Based on the theory of electrolytic strengthening technology, this paper introduced and developed prototype equipment for strengthening cutting edge of rotary cutter and put forward a calculation method of total electric quantity consumption during the electrolysis suitable for microcontroller. The M8 high-speed steel tap is taken as a strengthening example. After finished the strengthening process that it clearly see the results of the surface of tap was obviously polished by observing the micrograph. This equipment improves the reliability of electrolytic strengthening and the cost is relatively cheap.

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

A High Speed Video/Audio Stream Splitter for 4K Digital-Cinema

2006 ◽  
Author(s):  
Hirokazu Takahashi ◽  
Takahiro Murooka ◽  
Kan Toyoshima ◽  
Hitoshi Uematsu ◽  
Tetsuro Fujii
Keyword(s):  
High Speed ◽  
Digital Cinema ◽  
High Speed Video
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