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发动机曲轴必须经过精确的动平衡校正,这是毫无疑义的。但是,为了达到这一点,必须正确地选择转速。一般地说,转速越高,不平衡质量产生的离心力就越大,因而动平衡灵敏度就越高。所以,刚性转子动平衡校正时,都尽可能选用较高的转速。然而,对于发动机曲轴,尤其是六缸曲轴,却应该具体地分析。曲轴动平衡校正时,动平衡机本身所提供的转速,并不是不加分析地任意采用。其中较高的转速,是不能用来进行 相似文献
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探讨了航海类院校在校学生参加海事局统一理论考试和实操评估涉及到的问题和困难,提出一些改革建议。 相似文献
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In the two-step vitamin C fermentation process, its precursor 2-keto-L-gulonic acid was synthesized from L-sorbose by mixed culture of Gluconobacter oxydans and Bacillus megaterium. The interaction between Gluconobacter oxydans and Bacillus megaterium remains unclear and it is a challenge to mathematically model the mixed growth of these two strains. The Monod-type equations were previously proposed to describe the coupled growth of Gluconobacter oxydans and Bacillus megaterium. However, in this study, we modeled the interaction of these two strains in a macroscopic view by introducing the population theory. Taking account of the fact that the density or concentration of Gluconobacter oxydans or Bacillus megaterium was hardly to measure accurately in the mixed culture broth, the data of concentrations of the substrate and product were used to indirectly investigate the relation between these two strains. Three batch experiments were used to validate our model. And according to the values of identified parameters, the type of interaction between Gluconobacter oxydans and Bacillus megaterium was concluded to be predation, where Gluconobacter oxydans was predator, and Bacillus megaterium was prey. 相似文献
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<正>1新能源汽车专业的现状(1)师资数量匮乏。新能源汽车专业建设核心之一是师资建设,其重要性不言而喻。尽管当前很多职业院校都开设了新能源汽车专业,但配套的师资力量却没有跟上相应步伐。新能源汽车与传统燃油汽车在结构和原理上存在较大差异,对教师的综合能力要求更高。当前职业院校的新能源汽车专业教师主要来源于三部分,一部分是是从传统燃油汽车教师转变过去,第二部分是从企业聘请而来,第三部分是从高等院校毕业生中招聘而来。其中第一部分来源占比最大,这些教师具有丰富的教学经验,但系统化的新能源汽车专业知识还不够全面。有的教师虽具有较强的专业知识,但在教学育人经验等方面还不能满足要求。各类因素的叠加,就造成了新能源汽车专业教师的数量和专业性都远远不能满足当前职业院校的需要。 相似文献
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