Abstract: A method and system in which a programmed digital computer serving as a graphical "engine" is employed to construct an executable model for a complex system using a hierarchy of so called "Colored" Petri nets (CPN's or CP-nets). The operation of the complex system is specified in terms of a graphical net structure and formal net inscriptions, such as arc expressions and guards, which ensure development of a program, or executable model, and associated data structures, properly defining the system. Sophisticated syntax checks and other tools are provided for ensuring that the model so constructed conforms to a set of rules which guarantee valid system behavior.

Abstract: A cable adapted for well logging has an optical fiber core in which the optical fibers are protected from moisture and non-uniform stresses by first wrapping the fibers in a helical spiral around a solid, soft, deformable core material and then blanketing them with more of the same. Next the blanketed core is closely and tightly wound with several overlapping layers of a metallic tape jacket. The jacket buffers radial loads applied by other portions of the cable and forms a barrier against moisture penetration. The soft core and blanket have properties close to a liquid so that only uniform, essentially hydrostatic stresses are transmitted to the optical fibers.