Variations in the composition of the planets are largely responsible for the density differences.

行星构成成分的不同是造成密度差异的主要原因。

youdao

The bridge was actuated by sinusoid sweeping frequency wave, and then the power spectral density differences between the undamaged and damaged bridge were analyzed.

利用正弦扫频波激振钢桥，分析其损伤前后加速度反应功率谱密度的变化。

youdao

The computation results showed that the effect of density differences when velocity of flow was small was obvious to the boundary of laminar flow in the elevation difference pipeline.

结果表明，在大落差管道，流速不大的情况下，密度差对层流边界层影响比较明显。

youdao

OK, all this is a long way short of proof that traffic density alone causes these differences.

BBC: Crashes

There are also huge differences in population density across the country, with the population per square kilometre ranging from nine in Eilean Siar (the Western Isles) and the Highlands to 3, 395 in Glasgow.

BBC: Census shows 'highest' Scottish population ever

But it is possible to detect minute deviations in this signal, and these fluctuations - seen as mottling in the map - are understood to reflect the differences in the density of matter when the light parted company and set out on its journey all those years ago.

BBC: Planck satellite: Maps detail Universe's ancient light