Analysis of V1 Skating Technique of Olympic Cross-Country Skiers

1989 ◽  
Vol 5 (2) ◽  
pp. 185-207 ◽  
Author(s):  
Gerald A. Smith ◽  
Richard C. Nelson ◽  
Adam Feldman ◽  
Jeffrey L. Rankinen
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Lateral Motion ◽  
Kinematic Analyses ◽  
Cycle Lengths ◽  
Cross Country ◽  
Temporal Proportions ◽  
Mean Cycle ◽  
Relationship Of ◽  
The Relationship

The alternate stride or V1 skate technique was the predominant skiing method used in the free technique races of the 1988 Calgary Games. High-speed films were recorded of two free technique races: the Men’s 50 K and the Ladies' 20 K. A moderate and a steep uphill were sites of the filming, and both temporal and kinematic analyses were made. Times for a complete skating cycle tended to decrease on the steep hill (cycle rate increased). Cycle temporal proportions shifted to longer poling and recovery phases while the skating phases shortened on the steeper terrain. Mean cycle velocities (CV), cycle lengths (CL), and cycle rates (CR) were determined. Differences in kinematic relationships were noted: Male skiers included both those who emphasized CL to maximize CV and those who emphasized CR; females were relatively more consistent in emphasis on CR. In either case, center of mass (CM) motions were related to CR and CL. Increased lateral motion of CM tended to increase CL while decreasing CR. Ski edging angles were negatively correlated; a sharply edged ski on one side was usually associated with the other ski being relatively flat. The relationship of glide to ski flatness suggests that many skiers might benefit from skating with both skis relatively flat.

Kinematic Analysis of Alternate Stride Skating in Cross-Country Skiing

1988 ◽  
Vol 4 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Gerald A. Smith ◽  
Jill McNitt-Gray ◽  
Richard C. Nelson
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Rapid Evolution ◽  
Three Dimensional ◽  
Forward Direction ◽  
Double Poling ◽  
Cycle Lengths ◽  
Cross Country Skiing ◽  
Weak Side ◽  
Cross Country

Cross-country ski technique is undergoing rapid evolution. Alternate stride skating was the dominant technique during the 1985–86 racing season (double poling is synchronized with the “strong” side skate; no poling occurs with the “weak” side skate). High-speed films were made of elite male racers at the Holmenkollen World Cup races, Oslo, Norway (March 1986), skating up a 7° hill. Digitized data were filtered and processed to determine three-dimensional coordinates throughout a complete skating cycle. Ten skiers were analyzed, representing a range of performances. Over the 10-km race length, cycle rates for all skiers were similar; however, cycle lengths were significantly related to cycle velocity. The correlation between cycle velocity and length was r = 0.85. Ski angles were found to be asymmetrical. Weak-side ski angles were negatively related to cycle velocity; strong-side ski angles were similar for all skiers. Center of mass (CM) position throughout the cycle exhibited characteristic differences between faster and slower skiers. CM velocity vector direction was related to cycle velocity. Thus, faster skiers tended to maintain CM motion more nearly aligned with the forward direction.

Roller–rail parameters on the transverse vibration characteristics of super-high-speed elevators

2019 ◽  
Vol 43 (4) ◽  
pp. 535-543 ◽  
Author(s):  
Shunxin Cao ◽  
Ruijun Zhang ◽  
Shuohua Zhang ◽  
Shuai Qiao ◽  
Dongsheng Cong ◽  
...  
Keyword(s):  
High Speed ◽  
Relative Displacement ◽  
Guide Rail ◽  
Coupled Vibration ◽  
Vibration Acceleration ◽  
Vibration Model ◽  
Vibration Problems ◽  
Equivalent Method ◽  
Relationship Of ◽  
The Relationship

Interaction and wear between wheel and rail become increasingly serious with the increase in elevator speed and load. Uneven roller surface, eccentricity of rollers, and the looseness of rail brackets result in serious vibration problems of high-speed and super-high-speed elevators. Therefore, the forced vibration differential equation representing elevator guide rails is established based on Bernoulli–Euler theory, and the vibration equation of the elevator guide shoes and the car is constructed using the Darren Bell principle. Then, the coupled vibration model of guide rail, guide shoes, and car can be obtained using the relationship of force and relative displacement among these components. The roller–rail parameters are introduced into the established coupled vibration model using the model equivalent method. Then, the influence of roller–rail parameters on the horizontal vibration of super-high-speed elevator cars is investigated. Roller eccentricity and the vibration acceleration of the car present a linear correlation, with the amplitude of the car vibration acceleration increasing with the eccentricity of the roller. A nonlinear relationship exists between the surface roughness of the roller and the vibration acceleration of the car. Increased continuous loosening of the guide rail results in severe vibration of the car at the loose position of the support.

Aerodynamic Characteristics Analysis of High-Speed Train on Cutting under Crosswinds

2013 ◽  
Vol 300-301 ◽  
pp. 62-67
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Cutting Depth ◽  
Cutting Slope ◽  
Characteristics Analysis ◽  
Relationship Of ◽  
The Relationship

Cutting is an effective device to reduce crosswind loads acting on trains. The cutting depth, width and gradient of slope are important factors for design and construction of cutting. Based on numerical analysis methods of three-dimensional viscous incompressible aerodynamics equations, aerodynamic side forces and yawing moments acting on the high-speed train, with different depths and widths of cutting，are calculated and analyzed under crosswinds，meanwhile the relationship of the gradient of cutting slope and transverse aerodynamic forces acting on trains are also studied. Simulation results show that aerodynamic side forces and yawing moments acting on the train（the first, middle and rear train）decrease with the increase of cutting depth. The relationship between transverse forces (moments) coefficients acting on the three sections and the cutting depth basically is the three cubed relation. The bigger is cutting width，the worse is running stability of train. The relationship between yawing moments coefficients acting each body of the train and the cutting width approximately is the three cubed relation. The transverse Aerodynamic forces decreased gradually with the increase of the gradient of cutting slope, the relationship between yawing moments coefficients acting each body of the train and the gradient of cutting slope basically is the four cubed relation.

Signal Integrity Analysis of High-Speed Signal Connector USB3.0

2013 ◽  
Vol 760-762 ◽  
pp. 320-324
Author(s):  
Shi Lei Zhou ◽  
Ya Lin Guan ◽  
Xin Kun Tang
Keyword(s):  
Transmission Lines ◽  
High Speed ◽  
Signal Integrity ◽  
Signal Transmission ◽  
Simulation Software ◽  
Key Factor ◽  
Transmission Quality ◽  
Integrity Analysis ◽  
Relationship Of ◽  
The Relationship

High-speed signal connector has become a key factor of the signal transmission quality in telecommunications and data communications system. Signal integrity of connector is an inevitable problem. This paper based on the theory of differential transmission lines and Multimode S-Parameters, analyzed the USB3.0 connector signal integrity. And use 3D simulation software CST to build model and analyze the relationship of signal integrity and connectors geometry.

scholarly journals FORMING IDEAL 30 METER RUNNING TECHNIQUE IN 12-YEAR-OLD SCHOOLCHILDREN

2020 ◽  
Vol 20 (2) ◽  
pp. 108-115
Author(s):  
R Gimazov ◽  
G Bulatova
Keyword(s):  
High Speed ◽  
Structural Phase ◽  
Video Recording ◽  
Biomechanical Analysis ◽  
Second Stage ◽  
Group A ◽  
Relationship Of ◽  
The Relationship ◽  
Experimental Group ◽  
Parametric And Nonparametric Statistics

Aim. The article aims to achieve the accuracy of space-time characteristics of a running step in 11–12-year-old schoolchildren. Materials and methods. The article provides a comparative analysis of the results of training and improving the running step in the control and experimental groups. For an objective instrumental assessment of the second stage of training, a structural phase biomechanical analysis of movements based on data from high-speed digital video recording with a frequency of 240 frames per second was used. Changes in the technique of the running step in schoolchildren were analyzed in the take-off phase (when the supporting leg pushed away from the surface of the treadmill), in the float phase and in the amortization phase. Methods of parametric and nonparametric statistics were used. Results. In schoolchildren from the experi­mental group, a statistically significant positive increase in the coefficients of the relationship of the angular characteristics of the running step with the model indicators of the American sprinter Ryan Bailey was achieved, which objectively reflects a significant increase in 30 meter running speed. Conclusion. Taking into account the natural rules of nervous system mechanisms made it possible to objectively increase the efficiency of running technique in the experimental group.

Development of a Multi-Ball-Cantilever AFM for Measuring Resist Surface

2006 ◽  
Vol 18 (6) ◽  
pp. 698-704 ◽  
Author(s):  
Shujie Liu ◽  
◽  
Shuichi Nagasawa ◽  
Satoru Takahashi ◽  
Kiyoshi Takamasu
Keyword(s):  
High Speed ◽  
Surface Deformation ◽  
Surface Profile ◽  
Displacement Curve ◽  
The Finite Element Method ◽  
Measuring Surface ◽  
Surface Profiles ◽  
Relationship Of ◽  
The Relationship ◽  
Force Displacement

Semiconductor processing must be fast and highly accurate when measuring the surface profile of soft thin films such as photoresists. We propose doing so using a multi-ball-cantilever AFM, which covers a wide area at high speed. Each cantilever has a ball stylus with a diameter that does not plastically deform measured surfaces. We studied resist profiles and the influence of the AFM stylus on the resist surface. To verify our proposal’s feasibility, we simulated the relationship of the indenter shape, size, and load and resist surface deformation using the finite element method (FEM). We discuss the influence of the AFM stylus based on the force-displacement curve. Experiments using the multi-ball-cantilever AFM confirmed its feasibility for measuring surface profiles highly accurately.

The Research Progress of Melanin

2011 ◽  
Vol 204-210 ◽  
pp. 2057-2060
Author(s):  
Jian Ming Wang ◽  
Ai Hua Ao ◽  
Chang Sheng Qiao ◽  
Yu Zhong ◽  
Yuan Yuan Zhang
Keyword(s):  
High Speed ◽  
High Performance ◽  
Analytical Techniques ◽  
Research Progress ◽  
Countercurrent Chromatography ◽  
New Techniques ◽  
Wide Range ◽  
High Performance Capillary Electrophoresis ◽  
Relationship Of ◽  
The Relationship

The sources of melanin and the sorts of melanin are introduced. New techniques for extraction and analysis of natural melanin were introduced. New analytical techniques are high performance liquid chromatography, high-speed countercurrent chromatography, high performance capillary electrophoresis and chromatography-mass spectrometry. The relationship of polyketide melanogenesis molecular biology to that of nonmelanin-producing pathways in a wide range of fungi and other organisms is discussed. The applications of melanin are introduced.

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