通过几十年的研究，科学家们生产出的不同生物燃料分为四类：第一代，第二代，第三代和第四代。
During many decades study, scientists have produced different types of bio-fuels that into four types: first generation, second generation, third generation and fourth generation.
在研究过程中首先对多用途货船第三代和第四代产品的有关特性进行了分析，提出了第五代产品的主尺度设想，并进行了方案的技术设计。
To start with, the characteristics of the third and fourth generation ships were analysed. And the thought of principal dimensions and its design procedure of the fifth were given.
文中比较了第三代CNG (CNG3)和第四代cng (CNG4)气瓶的优缺点，通过缠绕理论和制造技术得到不同设计和爆炸压力的纤维增强塑料气瓶。
Advantages and disadvantages of CNG3 and CNG4 types are mentioned. The FRP vessel with different design and burst pressures are obtained by manufacturing technique and filament winding theory.
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