Visual Algorithm For Network Topology And Its Software Design

The purpose of this research is to get the algebraic expression of the transfer function from the visualized signal flow graph of a system and to use it for analyzing the system performance. The research in this thesis focuses on the software design of a visual simulation platform based on network topology method and visual programming language. The software VANT has been developed to implement this platform. The works of this research include:1. The modules of VANT are divided and their functions are defined by following the rules of software engineering and the requirements of visual programming language. The concepts essential to the software design of VANT are discussed.2. A novel algorithm routine based on Shannon-Happ's Formula for calculating the algebraic expression of the transfer function from signal flow graph of a system has been developed. This algorithm uses Johnson Method to find the fundamental loops in the signal flow graph. The combinations of no-interlaced loops are generated step by step through the pervious combinations, which are at a lower level. Calculating the Shannon-Happ's formula gets the transfer function. Some useful ideas are discussed for upgrading this algorithm.3. The approach to implement VANT with Borland C++ Builder 5.0 has been studied in details. The structure and features of Visual Graphics Editor, definitions of Graphic Icons and their dynamic manipulation comply with the rules of widely used VP software. Modules have been designed to accomplish the functions from visual modeling to simulation execution.4. Several tools for performing system analysis are developed on the basis of the transfer function i.e. system order reduction, the graphs of frequency characteristics, calculation of poles and zeros, analysis of system stability.5. The modules such as algorithm of network topology, visual modeling subsystem and analysis subsystem have been integrated into a complete simulation platform named VANT. This platform is capable of visual modeling of the signal flow graphs, performing simulation and system analysis. The systematical testing makes VANT a stable platform to accomplish the tasks such as visual modeling of the signal flow graphs, simulation and system analysis.