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E. Fraś, M. Górny and H. Lopez

Abstract

The paper discusses the reasons behind current trends for substituting cast iron castings by aluminum alloys. In particular it is shown that it is possible to produce thin wall castings (control arms, cantilevers and rotors) made of ductile iron without the development of chills, cold laps or misruns, and with a strength to weight ratio of up 87 MPa cm3/g. In addition, austenitizing at 900 °C for 20 minutes and then austempering in a salt bath at 350 °C for 15 minutes promotes the development of a fully ausferritic matrix in thin wall castings with a the strength to weight ratio increase of up to 154 MPa cm3/g. Finally, it is shown that thin wall castings made of ductile or austemperded cast iron can be lighter and with superior mechanical properties then their substitutes made of aluminum alloy.

Open access

G.Y. Perez-Medina, H.F. Lopez, F.A. Reyes-Valdés, A. Garza-Gomez and Luis M. López-Ochoa

Abstract

In this work a strip of a transformation induced plasticity (TRIP) steel was welded using gas metal arc welding (GMAW) and Laser CO2 welding (LBW) processes and the resultant strength and ductility of the welded joints evaluated. It was found that LBW lead to relatively high hardness in the fusion zone, FZ where the resultant microstructure was predominantly martensite. The relative volume fractions of phases developed in the welded regions were quantitatively measured using color metallography combined with X-ray diffraction analyses. It was found that the heat affected zone, HAZ developed the maximum amount of martensite (up to 32%) in the steel welded using LBW besides a mixture of bainite, retained austenite and ferrite phases. In contrast, a relatively low percent of martensite (10.8%) was found in the HAZ when the GMAW process was implemented.

Open access

Ciro José Brito, Bianca Miarka, Alfonso López Díaz de Durana and David H. Fukuda

Abstract

Previous studies indicate positive home advantage in judo; however, the factors that influence home advantage have yet to be fully explored. This study investigated the potential differences in technical-tactical variables between home and visiting athletes. A total of 1411 video recorded matches were analyzed (123 home, 1288 away) from 36 international judo competitions contested in 2011-12. The matches were analyzed by the following criteria: combat phases (approach, gripping, attack, defense, groundwork and pause), penalties (by the athlete or the opponent) and the types of attacks (with or without a score). Elite judo athletes competing in their home country attacked more frequently using trunk/leg couple techniques (p < 0.011) and scored more frequently with arm/leg couple techniques (p < 0.001), while visiting judo athletes received fewer scores from penalties (p < 0.001) and engaged in more frequent pauses during competition (p < 0.01). The results of this study provide an outline of technical-tactical differences that may contribute to home advantage in judo.

Open access

A. Vales-Vázquez, C. Casal-López, P. Gómez-Rodríguez and H. Blanco-Pita

Abstract

The purpose of this study was to compare the competitive profiles across the Spanish football leagues at the present time. The final standings (n=32) and results of the matches played (n=11,122) in the 2015/2016 season were analysed. Four categories of analysis were selected: Level of competitive balance of matches, Level of compactability of team standings, Magnitude of home-field advantage effect, and Degree of openness of the matches. Using statistical procedures for the comparison of means by analysis of variance (ANOVA) and the Chi-Squared test, it was concluded that in the panorama of Spanish football, the men's 2nd division stands out as the Championship that corresponds to a competitive profile with greater equality and that the women's 1st division presents the most unbalanced competitive profile (p < .05). A trend was also observed that indicated that the more professionalized Championships present a higher level of competitive balance of the matches, a higher level of compactability of the team standings, and a lower degree of openness of the matches with respect to the less professionalized Championships, due to the presence of statistically significant differences (p < .05) in the set of categories analysed.

Open access

J. Musial, J.E. Pecero, M.C. Lopez-Loces, H.J. Fraire-Huacuja, P. Bouvry and J. Blazewicz

Abstract

The Internet shopping optimization problem arises when a customer aims to purchase a list of goods from a set of web-stores with a minimum total cost. This problem is NP-hard in the strong sense. We are interested in solving the Internet shopping optimization problem with additional delivery costs associated to the web-stores where the goods are bought. It is of interest to extend the model including price discounts of goods.

The aim of this paper is to present a set of optimization algorithms to solve the problem. Our purpose is to find a compromise solution between computational time and results close to the optimum value. The performance of the set of algorithms is evaluated through simulations using real world data collected from 32 web-stores. The quality of the results provided by the set of algorithms is compared to the optimal solutions for small-size instances of the problem. The optimization algorithms are also evaluated regarding scalability when the size of the instances increases. The set of results revealed that the algorithms are able to compute good quality solutions close to the optimum in a reasonable time with very good scalability demonstrating their practicability.