但其排气速度却异常惊人，大约为化学燃料火箭的十倍—这使得离子推进器的效率非常高。
The exhaust velocity, though, is enormous—more than ten times that of a chemical rocket—and this makes ion propulsion extremely efficient.
从技术上讲，化学燃料火箭的最大速度增长比较低。这就是说，它们的排气速度还不足以将火箭的速度增加到非常快的程度。
In technical terms, chemical rockets have low maximum velocity growth, which means that their exhaust velocities are not high enough to impart very high speeds to the rocket.
采用宏观断口分析、化学成分分析及金相检验等方法，对发动机排气门杆断裂原因进行了分析。
By means of macroscopic analysis, chemical composition analysis and microstructure examination, the cracking reason of engine exhaust valve stem has been studied.
相比之下，火箭的化学能功率是推进力的一半乘以排气速度。
By comparison, the chemical power generated by a rocket equals one half the thrust times the exhaust velocity.
气体的控制包括：从排气流中除取污染物，使污染物产生化学反应，或改变产生污染物的流程。
The control of gases involves the removal of the pollutant from the exhaust gas stream, a chemical change in the pollutant, or a change in the process producing the pollutant.
这些污染物常常与其他有害物质，如铅、锌和地面臭氧一起出现。地面臭氧是汽车排气与太阳光一起发生光化学反应形成的一种烟雾成分。
The pollutants often occur with high levels of other toxins such as lead, zinc, and ground-level ozone, a component of smog formed by chemical reactions between car exhausts and sunlight.
针对汽车发动机排气管材质及性能要求，研制了一种薄壁高强韧铸态球墨铸铁排气管，确定了其化学成分和铸造工艺。
According to the requirements of automobile exhaust pipes on material and its properties, a high strength and toughness nodular cast iron of thin section castings has been developed.
研究结果表明，净化玻璃的化学成分、循环过热温度及净化过程中熔融玻璃和合金液的良好排气条件是影响净化效果的主要因素。
It was found that the chemical composition of glass, superheating temperature and the degasification in alloys and glass primarily influenced undercoolings of bulk liquid alloys.
研究结果表明，净化玻璃的化学成分、循环过热温度及净化过程中熔融玻璃和合金液的良好排气条件是影响净化效果的主要因素。
It was found that the chemical composition of glass, superheating temperature and the degasification in alloys and glass primarily influenced undercoolings of bulk liquid alloys.
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