The effect of a sharp change in the borehole diameter, such as that caused by a cave or rugose hole, on an induction log. In smooth boreholes of constant diameter, the effect of the borehole is well u [..]

A lighting effect caused by parabolic recessed troffers with a high cut-off angle that leaves the upper part of the room's walls relatively unlit and noticeably darker than the lower part of the walls.