A recent concrete example is Planning Engineer's posts on the grid stability «shadow cost» of increasing proportions of intermittent renewables. (judithcurry.com)
The company plans to do this by increasing the proportions of nickel and manganese, which are cheaper and more widely available. (newscientist.com)
Over the course of a week, gradually increase the proportion of new food in her dish while gradually decreasing the proportion of old food. (petpremium.com)