scholarly journals Snow machining and side slipping in alpine skiing

2020 ◽  
Author(s):  
Serguei Komissarov
Keyword(s):  
Laboratory Experiments ◽  
Approximate Theory ◽  
Alpine Skiing

A simple approximate theory of snow machining is developed and tested against the results of past laboratory experiments. It is also applied to side-slipping and traversing in alpine skiing, and yields realistic predic- tions which can be tested experimentally on real ski slopes. Eventually, the theory could be used in modelling of skiing turns involving the phaseof skidding.

scholarly journals Mechanics of side-slipping in alpine skiing: theory of machining snow and ice

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Serguei S. Komissarov
Keyword(s):  
Laboratory Experiments ◽  
Approximate Model ◽  
Alpine Skiing ◽  
Snow And Ice

AbstractSide-slipping (or skidding) is a feature of several manoeuvres in alpine skiing, including a few types of skiing turns. On hard snow, side-slipping involves removal of a thin top layer of snow, that makes it similar to machining of materials in manufacturing. In this paper, we briefly review the theory of machining and then propose an approximate model that can be used to describe side-slipping in skiing. We test this model against published results of laboratory experiments in machining of ice and snow and find agreement.

scholarly journals Mechanics of side-slipping in alpine skiing. Braking and skidded traversing

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Serguei S. Komissarov
Keyword(s):  
Field Studies ◽  
Approximate Theory ◽  
Alpine Skiing ◽  
Rigorous Testing ◽  
Fall Line

AbstractA recently proposed simple approximate theory of snow machining is applied to modelling of several basic manoeuvres of alpine skiing: fall-line side-slipping, traversing, and hockey stop. The results agree with the skiing practice and explain the abnormally high friction reported in previous field studies. They also prepare foundation for future rigorous testing of the theory, which will determine its accuracy and limits of applicability.

scholarly journals Laboratory experiments on whirlpools

1948 ◽  
Vol 194 (1038) ◽  
pp. 398-415 ◽  
Keyword(s):  
Laboratory Experiments ◽  
Tangential Velocity ◽  
Approximate Theory ◽  
Open Circular ◽  
Different Shapes

Two vertical pipes, placed on the axis of an open circular tank and fitted with trumpet entries of different shapes, were used in turn as overflows. Water was led into the tank in such a way that the stream approaching the trumpet under test possessed tangential velocity, which caused a vortex to appear in and above the trumpet. The relations between head and discharge were determined under various conditions of tangential supply. The formation of a vortex greatly reduced the discharge, the decrease being even more marked with the shallow than with the deep trumpet. At low heads, where the flow was controlled by the weir action of the trumpet crest, the discharge varied with the shape of the crest as well as with the irrotational constant c and the head, therefore (as with purely radial supply) it must be determined by experiment. At high heads with the trumpet flooded, the throat controlled the flow; within certain limits, the discharge was dependent chiefly upon c and the head measured with the throat as datum, and an approximate theory which ignores friction was verified. Two types of instability, ‘surging’ at low heads and ‘spluttering’ at high heads, were examined. Both were due to the collapse and subsequent re-formation of feeble vortices, which caused the discharge to vary with time in a periodic manner.

The runup of solitary waves

1987 ◽  
Vol 185 ◽  
pp. 523-545 ◽  
Author(s):  
Costas Emmanuel Synolakis
Keyword(s):  
Solitary Wave ◽  
Linear Theory ◽  
Solitary Waves ◽  
Nonlinear Theory ◽  
Laboratory Experiments ◽  
Breaking Waves ◽  
Asymptotic Result ◽  
Approximate Theory ◽  
Sloping Beach

This is a study of the runup of solitary waves on plane beaches. An approximate theory is presented for non-breaking waves and an asymptotic result is derived for the maximum runup of solitary waves. A series of laboratory experiments is described to support the theory. It is shown that the linear theory predicts the maximum runup satisfactorily, and that the nonlinear theory describes the climb of solitary waves equally well. Different runup regimes are found to exist for the runup of breaking and non-breaking waves. A breaking criterion is derived for determining whether a solitary wave will break as it climbs up a sloping beach, and a different criterion is shown to apply for determining whether a wave will break during rundown. These results are used to explain some of the existing empirical runup relationships.

scholarly journals Mechanics of wedge turns in alpine skiing

2020 ◽  
Author(s):  
Serguei Komissarov
Keyword(s):  
Coefficient Of Friction ◽  
Experimental Investigations ◽  
Approximate Theory ◽  
Alpine Skiing ◽  
The Coefficient Of Friction

A simple approximate theory of snow machining is applied to modelling successive wedge turns of alpine skiing. The results are in agreement with available experimental investigations of such turns. In particular, the model explains the abnormally high values for the coefficient of friction reported in these studies.

scholarly journals ON THE MAXIMUM RUNUP OF CNOIDAL WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 39
Author(s):  
Costas Emmanuel Synolakis ◽  
Manas Kumar
Keyword(s):  
Solitary Waves ◽  
Nonlinear Theory ◽  
Laboratory Experiments ◽  
Laboratory Data ◽  
Numerical Results ◽  
Asymptotic Result ◽  
Approximate Theory ◽  
Cnoidal Waves ◽  
Linear And Nonlinear ◽  
Monochromatic Waves

This is a study of the maximum runup of cnoidal waves on plane beaches. An approximate theory is described for determining the maximum runup of nonbreaking cnoidal waves. It is shown that the linear and nonlinear theory predict mathematically identical maximum runup heights. An asymptotic result is derived for the maximum runup of solitary waves, which are one limiting form of cnoidal waves. A series of laboratory experiments is described to support the theory. Other numerical results are presented that suggest that the runup of cnoidal waves is significantly higher than the runup of monochromatic waves with the same waveheight and wavelength. Preliminary laboratory data are also presented which suggest that, for certain cnoidal waves, the maximum runup is not a monotonically varying function of the normalized wavelength.

Covering of cometary nucleus by refractory crust and its evolution into asteroid-like body

1999 ◽  
Vol 173 ◽  
pp. 365-370
Author(s):  
Kh.I. Ibadinov
Keyword(s):  
Laboratory Experiments ◽  
Cometary Nucleus ◽  
Sublimation Rate ◽  
Cometary Nuclei ◽  
Short Period Comet ◽  
Short Period ◽  
Brightness Decrease ◽  
Crust Thickness ◽  
Ice Sublimation ◽  
Period Comet

AbstractFrom the established dependence of the brightness decrease of a short-period comet dependence on the perihelion distance of its orbit it follows that part of the surface of these cometary nuclei gradually covers by a refractory crust. The results of cometary nucleus simulation show that at constant insolation energy the crust thickness is proportional to the square root of the insolation time and the ice sublimation rate is inversely proportional to the crust thickness. From laboratory experiments resulted the thermal regime, the gas productivity of the nucleus, covering of the nucleus by the crust, and the tempo of evolution of a short-period comet into the asteroid-like body studied.

When Does Voice Have to be More Than Only Listening? Procedural Justice Effects as a Function of Confident Leadership

2010 ◽  
Vol 9 (2) ◽  
pp. 69-78 ◽  
Author(s):  
David De Cremer ◽  
Maarten Wubben
Keyword(s):  
Procedural Justice ◽  
Interaction Effect ◽  
Laboratory Experiments ◽  
Negative Emotions

The present research examined how voice procedures and leader confidence affect participants’ negative emotions and willingness to withdraw. It was predicted that receiving voice would be valued out of instrumental concerns, but only when the enacting leader was high in confidence. Two laboratory experiments indeed showed an interaction between type of voice (pre-decisional vs. post-decisional) and leader’s confidence (low vs. high) on participants’ negative emotions and willingness to withdraw. In particular, post-decision voice only led to more negative responses than did pre-decision voice when the enacting leader was high in confidence. Negative emotions mediated this interaction effect of type of voice on willingness to withdraw. Implications for integrating the leadership and procedural justice literatures are discussed.

Review of Laboratory Experiments in Psychology.

1968 ◽  
Vol 13 (10) ◽  
pp. 536-536
Author(s):  
Peter G. Polson
Keyword(s):  
Laboratory Experiments
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