Survey of the fatty acid composition of Canadian beef: Backfat and longissimus lumborum muscle

[EN]A survey of Canadian retail beef was undertaken with emphasis on the trans fatty acid (TFA) and conjugated linoleic acid (CLA) isomers, and compared with current health recommendations. Thirty striploin steaks were collected in the winter and summer from major grocery stores in Calgary (Alberta, Canada). Steak fatty acid compositions (backfat and longissimus lumborum muscle analysed separately) showed minor seasonal differences with lower total saturates (PB0.05) and higher total monounsaturates (PB 0.01) in winter, but no differences in total polyunsaturated fatty acids. The ratio of n-6 and n-3 polyunsaturated fatty acid in longissimus lumborum averaged 5.8. The average TFA content in longissimus lumborum was 0.128 g 100 g_1 serving size, and 10t-18:1 was found to be the predominant isomer (32% of total trans), while vaccenic acid was second most abundant (15% of total trans). The CLA content in longissimus lumborum was similar to that of backfat, ranging from 0.43 to 0.60% of total fatty acids and rumenic acid represented 60% of total isomers. Overall, there is still room for improvement in the saturated, mono- and polyunsaturated fatty acid composition of Canadian beef to meet general dietary guidelines for human consumption and additional targets should include reducing 10t-18:1 while increasing both rumenic and vaccenic acids.

Dynamic optimization of track components to minimize rail corrugation

In this paper, the influence on corrugation of the most significant track parameters has been examined. After this parametric study, the optimization of the track parameters to minimize the undulatory wear growth has been achieved. Finally, the influence of the dispersion of the track and contact parameters on corrugation growth has been studied. A method has been developed to obtain an optimal solution of the track parameters which minimizes corrugation growth, thus ensuring that this solution remains optimum despite dispersion of track parameters and wheel-rail contact uncertainties. This work is based on the computer application RACING (RAil Corrugation INitiation and Growth) which has been developed by the authors to predict rail corrugation features.

Design of an optimised wheel profile for rail vehicles operating on two track gauges

This paper sets out an optimum synthesis methodology for wheel profiles of railway vehicles in order to secure good dynamic behaviour with different track configurations. Specifically, the optimisation process has been applied to the case of rail wheelsets mounted on double gauge bogies, that move over two different gauges, which also have different types of rail: the Iberian gauge (1668 mm) and the UIC gauge (1435 mm). Optimisation is performed using Genetic Algorithms and traditional optimisation methods in a complementary way. The objective function used is based on an ideal equivalent conicity curve which ensures good stability on straight sections and also proper negotiation of curves. To this end the curve is constructed in such a way that it is constant with a low value for small lateral wheelset displacements (with regard to stability), and increases as the displacements increase (to facilitate negotiation of curved sections). Using this kind of ideal conicity curve also enables a wheel profile to be secured where the contact points have a larger distribution over the active contact areas, making wear more homogeneous and reducing stresses. The result is a wheel profile with a conicity that is closer to the target conicity for both gauges studied, producing better curve negotiation while maintaining good stability on straight sections of track. The paper shows the resultant wheel profile, the contact curves it produces, and a number of dynamic analyses demonstrating better dynamic behaviour of the synthesised wheel on curved sections with respect to the original wheel.

Modelling rail corrugation with specific track parameters focusing on ballasted track and slab track

The objective of this paper is to compare 3 types of track (high performance ballasted track, STEDEF and AFTRAV) from the corrugation growth point of view. This work has considered different vehicle speeds and track radii, and the results have taken into account the four wheels of a bogie. These tracks have been studied using Finite Elements with Nastran-Patran and RACING, a tool developed in Matlab by the authors which estimates the corrugation growth tendency. The tracks are studied using the Finite Strip Method and the Periodic Structure Theory. Lateral and vertical receptances for track and vehicle have been obtained, as well as the corrugation growth functions. In the paper the tracks are ranked according to corrugation development.

Suspensión trasera regulable para un a moto de competición: alternativa Uni-Track

En el presente trabajo se realiza el diseño de una suspensión trasera regulable para una moto de competición. Se realizan una serie de estudios cinemáticos de diferentes modelos de suspensión (suspensión clásica, y suspensión de bieletas o progresivo) con el fin de comprender el comportamiento del mecanismo en las diferentes situaciones de servicio y definir la relación que existe entre las fuerzas, la geometría y la rigidez. Posteriormente se realiza el diseño de la geometría de un modelo de suspensión de bieletas específico (Uni-Track), el cual cumple con los requisitos establecidos y con una serie de parámetros que garantizan que el comportamiento del mecanismo sea competitivo y que mantenga una relación óptima entre servicio y confort. Se estudian las diferentes alternativas de variaciones geométricas que se pueden dar en el modelo, para diseñar una suspensión regulable. Finalmente se diseña cada elemento que compone la suspensión por el Método de Elementos Finitos y se seleccionan los elementos de unión, así como los procesos de fabricación de aquellas piezas que deban de ser fabricadas en el taller.

The Health Effects of Climate Change: A Survey of Recent Quantitative Research

44 p.