tailieunhanh - Recent Advance in Modelling and Simulation_2

This book collects original and innovative research studies concerning modeling and simulation of physical systems in a very wide range of applications, encompassing micro-electro-mechanical systems, measurement instrumentations, catalytic reactors, biomechanical applications, biological and chemical sensors, magnetosensitive materials, silicon photonic devices, electronic devices, optical fibers, electro-microfluidic systems, composite materials, fuel cells, indoor air-conditioning systems, active magnetic levitation systems and more. Some of the most recent numerical techniques, as well as some of the software among the most accurate and sophisticated in treating complex systems, are applied in order to exhaustively contribute in knowledge advances | 19 New Methods to Model and Simulate Both Air Exchange and Particle Contamination of Portable Devices Markus Olin1 Lauri Laakso2 Jukka Hannula3 Timo Galkin4 Kyosti Vakevainen5 Kari Hartikainen6 and Eini Puhakka1 1 VTT Technical Research Centre of Finland 2 University of Helsinki Department of Physical Sciences 3 Nokia Corporation 4 Nokia Siemens Networks 5 Metso Automation 6 Ambertec Ltd Finland 1. Introduction Developed countries have made great efforts to improve air quality through adopting clean air plans which have included measures such as demanding emission and air quality regulations continuous air quality monitoring in urban industrial centres and use of cleaner fuels such as natural gas. Meanwhile in developing countries there is a clear phenomenon of migration from the countryside to the city which has brought with it greater emissions into the atmosphere mainly produced by biofuels used in cooking and heating and increasing traffic Scholorling 2000 Laakso et al. 2006 with the additional difficulty that in these countries the tendency is to have a stock of old badly maintained vehicles. These factors have produced far-reaching changes in air quality in urban contexts especially in the 1990s when the majority of clean air plans were tightened up Baldasano et al. 2003 . At the same time markets for mobile devices have grown strongly in areas with high particle and pollutant concentrations . Asia Africa and South America . Exposure to a high amount of fine particles and the resulting contamination and corrosion is a potential future reliability risk. To avoid this risk one must understand the basic physics of particle drifting and in addition know the chemical and physical properties of the atmospheric aerosol particles. This includes the mapping and investigation of atmospheric measurements. Telecommunication equipment is exposed to various kinds of stresses in the course of its life Roberge et al. 2002 Hannula 2001 Ojala Vakevainen 2001 Vakevainen et .