The Determinants of Soccer Player Substitutions: a Survival Analysis of the Spanish Soccer League

This paper analyzes the pattern of player substitutions during a soccer match, using data from the First Division (Primera División) of the Spanish National Soccer League in the 2004-2005 season. To do so, an inverse Gaussian hazard model is adopted to analyze the first substitutions of each team that take place at half-time and in the second half of matches. The results show that the most important factor is the score as it stands prior to the time of the player substitution. Furthermore, defensive substitutions are made later in the match than offensive substitutions. We also find some evidence that the home team makes more substitutions than the visiting team in the halftime interval.hazard model; soccer substitutions; strategy.

Aproximación de homeomorfismos continuos Hölder por homeomorfismos afines a trozos

En esta comunicación tratamos el problema de la aproximación de homeomorfismos por homeomorfismos afines a trozos. El resultado principal es el siguiente: cualquier homeomorfismo continuo H¨older de exponente α ∈ (0, 1] definido en un dominio de R2 con frontera poligonal, y cuyo inverso tambi´en es continuo H¨older de exponente α, puede ser aproximado en la norma H¨older de exponente β, para un cierto β < α, por homeomorfismos afines a trozos sobre triangulaciones

Asymptotic description of maximum mistuning amplification of bladed disk forced response

The problem of determining the maximum forced response vibration amplification that can be produced just by the addition of a small mistuning to a perfectly cyclical bladed disk still remains not completely clear. In this paper we apply a recently introduced perturbation methodology, the Asymptotic Mistuning Model (AMM), to determine which are the key ingredients of this amplification process are, and to evaluate the maximum mistuning amplification factor that a given modal family with a particular distribution of tuned frequencies can exhibit. A more accurate upper bound for the maximum forced response amplification of a mistuned bladed disk is obtained from this description, and the results of the AMM are validated numerically using a simple mass-spring model