Optimization of fast tool servo diamond turning for enhancing geometrical accuracy and surface quality of freeform optics

Fast tool servo (FTS) in ultra-precision diamond turning is an efficient technique for high-precision fabrication of freeform optics.However, the currently adopted constant scheme for control point sampling takes no account of the shape variation of the desired surface, which might lose some micro features and result in low form accuracy and non-un

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Biochar boosts tropical but not temperate crop yields

Applying biochar to soil is thought to have multiple benefits, from helping mitigate climate change [ 1 , 2 ], to managing waste [ 3 ] to conserving soil [ 4 ].Biochar is also widely assumed to boost crop yield [ 5 , 6 ], but there is controversy regarding the extent and cause of any yield benefit [ 7 ].Here we use a global-scale meta-analysis to i

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