An improved rocket-borne electric field meter for the middle atmosphere

Improvements in a rocketborne electric field meter designed to measure the atmosphere's electric field and conductivity in the middle atmosphere are described. The general background of the experiment is given as well as changes in the instrument and data processing schemes. Calibration and testing procedures are documented together with suggestions for future work

Optimal Approximation of Elliptic Problems by Linear and Nonlinear Mappings I

We study the optimal approximation of the solution of an operator equation Au=f by linear and nonlinear mappings