On an Integrated Transfer Matrix method for multiply connected mufflers

The commercial automotive mufflers are generally of a complicated shape with multiply connected parts and complex acoustic elements. The analysis of such complex mufflers has always been a great challenge. In this paper, an Integrated Transfer Matrix method has been developed to analyze complex mufflers. Integrated transfer matrix relates the state variables across the entire cross-section of the muffler shell, as one moves along the axis of the muffler, and can be partitioned appropriately in order to relate the state variables of different tubes constituting the cross-section. The paper presents a generalized one-dimensional (1-D) approach, using the transfer matrices of simple acoustic elements, which are available from the literature. The present approach is robust and flexible owing to its capability to construct an overall matrix of the muffler with the transfer matrices of individual acoustic elements and boundary conditions, which can then be used to evaluate the transmission loss, insertion loss, etc. Results from the present approach have been validated through comparisons with the available experimental and three-dimensional finite element method (FEM) based results. The results show good agreement with both measurements and FEM analysis up to the cut-off frequency. (C) 2011 Elsevier Ltd. All rights reserved.

A rational fraction polynomials model to study vertical dynamic wheel-rail interaction

This paper presents a model designed to study vertical interactions between wheel and rail when the wheel moves over a rail welding. The model focuses on the spatial domain, and is drawn up in a simple fashion from track receptances. The paper obtains the receptances from a full track model in the frequency domain already developed by the authors, which includes deformation of the rail section and propagation of bending, elongation and torsional waves along an infinite track. Transformation between domains was secured by applying a modified rational fraction polynomials method. This obtains a track model with very few degrees of freedom, and thus with minimum time consumption for integration, with a good match to the original model over a sufficiently broad range of frequencies. Wheel-rail interaction is modelled on a non-linear Hertzian spring, and consideration is given to parametric excitation caused by the wheel moving over a sleeper, since this is a moving wheel model and not a moving irregularity model. The model is used to study the dynamic loads and displacements emerging at the wheel-rail contact passing over a welding defect at different speeds.

Reviews: making mathematics with needlework

Review of Making Mathematics with Needlework, edited by Sarah-Marie Belcastro and Carolyn Yackel, published by AK Peters Ltd, 2007 (ISBN 978-1-56881-331-8).

Vías y escenarios de la transformación laboral: aproximaciones teóricas y nuevos problemas

Los procesos de globalización y de reestructuración empresarial apuntan a transformaciones en las formas de trabajo, en las relaciones laborales, en las identidades de los trabajadores y en las profesiones. Investigar y reflexionar sobre estos campos del saber se hace más acuciante hoy en día debido a que dichos cambios no apuntan necesariamente a mejoras en la calidad de vida de los trabajadores ni a la institucionalización de la negociación de las relaciones laborales en el espacio empresarial.Reconstruir el mundo del trabajo desde diversos puntos de vista teóricos y desde abordajes empíricos, tanto nacionales como internacionales, es el esfuerzo del libro. Problemáticas como la construcción social del trabajo en categoría de empleo; las relaciones laborales en España, Venezuela, México y Colombia; la transformación productiva vinculada a la introducción de tecnologías de la información y la comunicación (TIC´s) y la configuración de redes empresariales; la informalidad; las identidades profesionales y la educación como mecanismo de movilidad social, hacen parte del complejo y cambiante mundo del trabaja, expuestos en este libro.

Condicions de treball al món, alternatives de canvi : organització dels treballadors i comerç just. 'Condiciones de trabajo en el mundo, alternativas de cambio : organización de los trabajadores y comercio justo'.

Resumen del documento en catalán. También disponible en castellano

Globalitzar els drets laborals. 'Globalizar los derechos laborales'.

El vídeo ofrece una explicación de qué es la globalización económica, de los problemas que genera aplicada desde las doctrinas neoliberales y de cómo afecta a los derechos laborales de los trabajadores alrededor del mundo.

Quantificação de microrganismos ruminais de novilhos alimentados com cana-de-açúcar ou feno de tifton com diferentes relações volumoso:concentrado

Pós-graduação em Zootecnia - FCAV

Evolution of sleep and sleep EEG after hemispheric stroke

The evolution of subjective sleep and sleep electroencephalogram (EEG) after hemispheric stroke have been rarely studied and the relationship of sleep variables to stroke outcome is essentially unknown. We studied 27 patients with first hemispheric ischaemic stroke and no sleep apnoea in the acute (1-8 days), subacute (9-35 days), and chronic phase (5-24 months) after stroke. Clinical assessment included estimated sleep time per 24 h (EST) and Epworth sleepiness score (ESS) before stroke, as well as EST, ESS and clinical outcome after stroke. Sleep EEG data from stroke patients were compared with data from 11 hospitalized controls and published norms. Changes in EST (>2 h, 38% of patients) and ESS (>3 points, 26%) were frequent but correlated poorly with sleep EEG changes. In the chronic phase no significant differences in sleep EEG between controls and patients were found. High sleep efficiency and low wakefulness after sleep onset in the acute phase were associated with a good long-term outcome. These two sleep EEG variables improved significantly from the acute to the subacute and chronic phase. In conclusion, hemispheric strokes can cause insomnia, hypersomnia or changes in sleep needs but only rarely persisting sleep EEG abnormalities. High sleep EEG continuity in the acute phase of stroke heralds a good clinical outcome.

Orchestration of gene expression across the seasons : Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster

Funding for work in the laboratory of PB was supported by Scottish Government Rural and Environment Science and Analytical Services Division, BBSRC (grant BB/M001504/1), British Society for Neuroendocrinology (research visit grant to IP). Work in the laboratory of SS was supported by a grant from the DFG (Ste 331/8-1). We thank Siegried Hilken, Marianne Brüning, Dr. Esther Lipokatic-Takacs and Dr. Frank Scherbarth at UVMH for technical assistance. We thank Graham Horgan of Bioinformatics, Statistics Scotland for assistance with some of statistical tests.