It is also pointed out in the thesis that when trains are running in railway line, using double receivers, fusing GPS single point position units with other locating sensors is of great value.

对大型车站、道口、大型个体工程等处则建立连续运营GPS差分基准站，采用动态差分GPS数据与其它传感器数据组合定位的方案，以提高列车定位的精度。

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The second asteroid belt lies at about 20 astronomical units from the star, or a position comparable to Uranus in our solar system.

第二个行星带距离它的恒星为20个天文单位，这相当于太阳系中天王星的位置。

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Because it takes three units where there's only four choices at each position to have at least 20 unique combinations.

因为每个位点上仅有四种可能性,只有采用三个碱基一组,才能取得至少二十种不同的组合方式

耶鲁公开课 - 生物医学工程探索课程节选

He said he believed the retail sector in York was in a strong position and units in the Castle Piccadilly scheme would let quickly.

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But getting the units into position has proved nearly as vexing.

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To improve competitiveness, 3m plans reduce its businesses to five from six, one of several large manufacturer hoping to better its position through streamlining its units.

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