An ATM switching system 1 is provided with an ATM switch 11, a reserved connection memory 12 for storing reserved connection information, a call history memory 13 for maintaining call histories of requests for connection from subscriber’s terminal units 2\u22121 to 2\u2212n, and a call-signal processing section 15. The rig is positioned over a well, with the well having a tubular string disposed therein. At least one port allows fluid to enter into or leave from the enclosed variable volume in a controllable manner. The use of a series of proxy cubes in place of the co-ordinate pair related original CUBEs of seismic data results in several advantages including reduced processing time and better accuracy at the boundaries of the subject section. A source of radiation capable of exciting photoluminescence of the photoluminescent particles is optically coupled to the liquid suspensions.