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基于离轴三反光学系统和多列线阵探测器,设计了一种具有宽波段高光谱分辨率的中阶梯光栅光谱仪.首先,以仪器性能指标为约束优化中阶梯光栅的结构参数,使光栅在保证高色散的同时将宽工作波段折叠重合在较小的光谱级次内,并采用多列线阵探测器采集信号.然后,以离轴三反光学系统作为会聚镜,以离轴抛物镜作为准直镜,实现了高色散宽自由光谱的像差校正.最终,设计的中阶梯光栅光谱仪工作波段为400~900 nm,F数为4.5,光谱分辨率在402.31,541.82,870.48 nm时分别为0.003,0.004,0.005 nm,系统体积为380 mm×325 mm×230 mm. 相似文献
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Constraint-based models such as flux balance analysis
(FBA) are a powerful tool to study biological metabolic
networks. Under the hypothesis that cells operate at an optimal
growth rate as the result of evolution and natural selection, this
model successfully predicts most cellular behaviours in growth rate.
However, the model ignores the fact that cells can change their
cellular metabolic states during evolution, leaving optimal
metabolic states unstable. Here, we consider all the cellular
processes that change metabolic states into a single term `noise',
and assume that cells change metabolic states by randomly walking in
feasible solution space. By simulating a state of a cell randomly
walking in the constrained solution space of metabolic networks, we
found that in a noisy environment cells in optimal states tend to
travel away from these points. On considering the competition
between the noise effect and the growth effect in cell evolution, we
found that there exists a trade-off between these two effects. As a
result, the population of the cells contains different cellular
metabolic states, and the population growth rate is at suboptimal
states. 相似文献
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