Abstract: An apparatus for suspending above a shooting location comprises an inflatable panel and a plurality of attachment points from which the panel may be suspended. An inflation apparatus directs air into the panel through an air inlet to inflate the panel.

Abstract: Methods are provided for fitting a curve to a set of data values using a least absolute value (LAV) cost function. The set of data values may comprise m sets of data values. The method takes advantage of contraction mapping to determine a number n<m of individual equations which are interpolated by the curve to be fitted, where n corresponds to the number of parameters x1, x2, . . . , xn to be ascertained for the curve to be fitted. The method then involves solving the n selected equations to determine the n parameters x1, x2, . . . , xn of the curve to be fitted. Selection of these parameters ensures that the curve to be fitted minimizes the LAV cost function.

Abstract: An underground drilling method and apparatus generates intense pressure pulses at a location at the surface. The pressure pulses propagate down through a drill string to a drill bit. The pulses may be generated by creating water hammer in flowing drilling mud. Intensity of the acoustic pulses is increased in the bit nozzles. Vigorous pulsing of the fluid exiting the bit nozzles results in better cleaning of the hole bottom and faster drilling. The pulses may be used to drive the operation of various down hole tools. One type of tool has multiple pistons arranged in series. High pressure pulses move the pistons to generate strong mechanical vibration in the drill string. Vibration of the drill string may also reduce the friction between the drill string and the hole, resulting in lower torque requirements.