In this paper, based on flame propagation a mathematical model of formation and desorption of unburned hydrocarbon in top-land crevice of spark ignition engines has been established.

基于火焰传播过程建立了火花点火发动机顶环岸间隙处未燃碳氢生成和释放过程的数学模型，并利用模型进行了顶环岸间隙处未燃碳氢生成过程的数值模拟计算。

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Once Barcelona had settled after the early goal, there was no way back for United as several changes in formation failed to produce a spark and Wayne Rooney was unable to exert any influence on events, first from the left flank and then from the centre.

BBC: Barcelona 2-0 Man Utd