A method of evaluating a design model, including:providing a design model;simulating a behavior of at least one digital user in said model;simulating at least one environmental effect modulated by said model and affecting or affected by at least one of said at least one digital user; andevaluating said design model based on a result of said simulations. The system includes a cable shield connector having a rigid, electrically conductive bond plate which is mounted to the fiber optic cable by at least one hose clamp. A second gas flow signal has the same polarity for either direction of gas flow in the conduit. Divergently configured electrodes reduce the spark voltage at high operating pressures and the energy required for ignition. The pickup includes light sources corresponding to the record media, a drive circuit for driving one of the light sources, a switch for switching a connection between the drive circuit and one of the light sources, and a control circuit for controlling the drive circuit and the switch. Each cluster includes a set of valid URL parts that are close according to a distance measure, and has a representative URL part having a known signature.