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This work present lap welding of zinc coated sheets and leads to the realization of an industrial process. The difficulty comes from the fact that the zinc boiling point (1180K) is lower than the steel melting point (1800K) leading to violent boiling of zinc in steel. We choose a two-spots process: first one concerns the zinc coating vaporization; second one allows welding. Previously, we develop a numerical modelling that permits a process parameters choice and limits the plan of experimentations. Scanning speed, laser power, size and shape of the two spots were optimised. Our numerical software leads to the choice of a zinc vaporization elliptic spotlight. Experimentations confirm the predicted tendency.

Interest has been growing in many countries in the potential use of diesel particulate filters (DPF). This type of after treatment technology has been shown to make very significant reductions in both the mass of particulate emitted in diesel exhaust gas, and also in the number of fine particulates, which have been linked in recent years with concerns for human health. Work carried out during a development programme investigating the capability of fuel soluble metallic additives to assist DPF regeneration, indicated superior performance from a novel combination of metals in fuel soluble form. Earlier work showed that a fuel soluble combination of organo-metallic additives based on sodium and strontium gave very effective regeneration characteristics, and was capable of burning out carbon at temperatures from about 160°C.

The particulate matter emitted by transports, in particular Diesel vehicles, has been considered toxic for many years, and is subject to world-wide emission standards. Recently, size distribution and particulate number has emerged as influential parameters of particulate toxicity. Over the past twenty years, many technologies have been studied for the removal of Diesel particulates. These technologies include numerous kind of traps, that are efficient mainly for solid particles. The work presented here has been devoted to the study of the influence of various traps on particulate size distribution and number, by means of SMPS (Scanning Mobility Particle Sizer) technique, in the exhaust of a VW 1.9 I TDI engine set in an engine test cell. The candidates tested are the well known Corning wall-flow monolith, the 3M wound ceramic fibre cartridge, the Buck knitted fibre cartridge and the HJS/SHW sintered metal trap.

One of the most promising ways to insure the periodic regeneration of a particulate trap, consists of additising the fuel with organo-metallic compounds. The present paper deals with a novel alkali product, able to promote natural regenerations, for exhaust temperatures as low as 200 °C, and treatment rates as low as 5 ppm metal. Tests have been carried out on a soot reactor and on an engine bench, with various trap locations in the exhaust, showing that the regeneration occurrence depends on temperature, soot mass loaded inside the porous structure and engine conditions. A complete trap cleaning still needs gas temperatures up to 400 °C, which can be encountered for high load conditions of the engine.