<正>为了揭示公益林的生态效益价值，促进政府和社会持续投资公益林建设，保障公益林经营事业的发展，笔者应用影子工程法、等效替代法、费用分析法、市场替代法等原理，对广西公益林的生态效益进行价值评价。结果表明：广西562.87万hm2公益林（森林和灌木）的主要生态效益价值为137.39亿元/a，其中，涵养水源效益价值69.25亿元/a，保育土壤效益价值15.72亿元/a，固碳制氧效益价值46.53亿元/a，净化环境效益价值4.81亿元/a，森林游憩价值1.08亿元/a。公益林生态效益价值是其经济价值（12.15亿元）的11.3倍，生态价值远大于经济价值。

Balance of engine’s exciting vibration sources while the engine normally vibrated was analyzed, the engine vibrating forms on the frame were discussed. The results showed that the overturn moment is the main exciting vibration source which will change when individual cylinder power changes. Because of overbalanced cylinder power, every cylinder’s nonmain harmonic overturn moments (appearing in many harmonics and uniting together now) should offset each other which lead to worsen the balance of the gross overturn moment, and aggravate engine vibrating. Finally,an engine was experimented by the method of the vibration analysis.