Generation of Multi-Scroll Attractors Without Equilibria Via Piecewise Linear Systems

In this paper we present a new class of dynamical system without equilibria which possesses a multi scroll attractor. It is a piecewise-linear (PWL) system which is simple, stable, displays chaotic behavior and serves as a model for analogous non-linear systems. We test for chaos using the 0-1 Test for Chaos of Ref.12.Comment: Corresponding Author: Eric Campos-Cant\'o

Intermodal Energy Transfer in a Tapered Optical Fiber: Optimizing Transmission

We present an experimental and theoretical study of the energy transfer between modes during the tapering process of an optical nanofiber through spectrogram analysis. The results allow optimization of the tapering process, and we measure transmission in excess of 99.95% for the fundamental mode. We quantify the adiabaticity condition through calculations and place an upper bound on the amount of energy transferred to other modes at each step of the tapering, giving practical limits to the tapering angle.Comment: 29 pages, 17 figure

A METHOD FOR DETERMINING THE INDMDUAL SPORT TECHNIQUE IN JAVELIN

INTRODUCTION. The javelin throwing skill is within the movement pattern which objective is to reach the maximum velocity of human body chain free end at the release instant. It has been proved for numerous researchers that segments reach the maximum speed consecutively and beginning for the proximal segments. This one has done to think that throwing pattern is based in the energy transmission among segments. However, nobody has found until to day quantitative relations among energy exchanges which allow to establish, in an objective way, differences among throws of one subject. Also, the trunk has been considered normally like a bar, that is, no differing thorax, abdomen and pelvis. Finally, to remark that it has not been found any research which calculates the kinetic energy of segments considering them with their six degrees of freedom. Therefore, the main objective of this work will be to develop individual technique patterns based in the energy exchange among segments. This model should allow to assess the performance objectively. The methology has been based in the filming of the movement by mean two highspeed cine-camaras and the latter determination of the 3D coordinates of the body landmarks. DLT algorithm was used. Previously to the experimental phase, a theorical model was develop for the computation of human body kinetic energy. The model considers the body like a solid rigid (six degrees of freedom)system and takes like input the 3D coordinates of body markers. The model determines a local reference system in each segment and after calculates the kinetic energy of the 17 segments which define the human body (included the javelin). The kinetic energy is considered like the addition of a traslational and arotational terms. Two elite thowers were the subjects. 36 throws were analyzed. The energy increments of segments and groups of segments in the registered throws were the variables. Each subject was considered separately. RESULTS. The linear regression study confirmed the energy exchange among segments general pattern in both athletes. The discriminate analysis proved the existence of an individual pattern -mathematical model- for each thrower. The discriminate function allowed to differ objectively between good a bad throws. Also it informed about the technique used for the subject. CONCLUSIONS. A new model for calculating the kinetic energy of segments has been developed. A procedure for a quantitative determination of the individual pattern of movement in throwing, based on the using of discriminant analysis, has been developed REFERENCES. -Bartlett, R.M. y Best,R.J. (1988) The biomechanics of javeling throwing: a review. J. Sports Sci. 6(1), 1-38.-Caldwell, G.E. y Fonester, L.W. (1992)Estimates of mechanical work and energy transfers: demostration of a rigid bodypower model of the recovery leg in gait.Med. Sci. Sports Exerc. 24(12). 1396-1412.-Menzel, H.J. (1987) Transmission ofpartial momenta in javelin throw. EnBiomechanics X-6, (Editado por Jonsson,B.) Human Kinetics Publishers,Champaign, 643-647

Relación entre el tiempo de retraso del segundo apoyo y el impulso ejercido en batida del salto vertical

El propósito de este trabajo ha sido determinar la importancia que tiene el retraso del segundo apoyo en la batida del salto vertical sobre las componentes del impulso total, impulso de frenado e impulso de aceleración. Se han analizado 61 saltos verticales realizados por estudiantes de educación física. Para el registro de los datos se han utilizado dos plataformas de fuerza, (Dinascan – IBV), una para cada apoyo, a una frecuencia de 250 Hz y sincronizadas temporalmente a una cámara de vídeo de alta velocidad (Redlake Motion Space 1000 S). Los resultados han puesto de manifiesto que el retraso del segundo apoyo no afecta a la altura de salto. Cuando se incrementa el tiempo de retraso del segundo apoyo, se reduce el impulso total de componente vertical (r = -0.52; p<0.001), y el impulso vertical durante el periodo de frenado (r = -0.61; p<0.001). No se ha encontrado relación entre el retraso del segundo apoyo y el impulso de aceleración vertical ejercido durante el periodo de aceleración