Methods and apparatus for generating a hierarchical representation of a circuit include obtaining a netlist corresponding to the circuit, the circuit including a plurality of subcircuits. When an application is completed, the library unit receives an application ID of the completed application, detects a resource name corresponding to the received application ID in the table, and collects a resource specified by the resource name. The tool includes a housing having a cylindrical wall with a plurality of perforations therethrough and an interior chamber therein. In an embodiment, a gradient induction instrument consists of a tri-axial transmitter array and up to 27 pairs of receiver coils, measuring some or all magnetic gradient components. The second end of the tube is next secured to the second end of the portion of the fluid delivery system.