Study Of Modeling Methods And Constructing Technologies For Web-Based Virtual Laboratory And Implementation Of VL

Experiment teaching has been playing an increasingly important role in high education. It's a key measure to improve the students' ability. As an essential and beneficial supplement to the traditional experiment, virtual experiments not only save a lot of education funds, but also extend the experiments in time and space effectively.This thesis discusses on the construction of web-based virtual laboratory (VL) from theoretical research, technological route and application development. Has, emphatically, discussed relevant theories, modeling methods and key technologies of VL, introduced implementation of "the Web-Based Virtual Laboratory for Electric and Electronic Experiment" in detail.This thesis, first of all, describes the VL's basic conception, main functions and characteristics, basic principle and methods for constructing VL, gives the teaching model of virtual experiments from the point of view of theory aspect.From technology and method aspect, this thesis discusses the modeling and simulating methods and realizing technologies to development the VLs, presents a modeling and simulating method of virtual apparatus for VL based on Object-Oriented and components, such as establishment of mathematics models, static and dynamic image models, the cooperation of models, etc. Object-Oriented method is comprehensible, expansible and reusable. Component-based modeling method derives from the Object-Oriented method. Compared with Object-Oriented method, the modeling granularity of component-based method is bigger and more reusable. On the basis of comparing and analyzing some technological scheme of VL, a technological scheme for web-based virtual laboratory with component technology is proposed. In the scheme, VBScript and ActiveX controls act as the client tools, XML acts as the communication bridge between different objects, the integration of COM/DCOM acts as the simulating and computing tools in the server. By using the scheme, the efficiency of developing the VL can be improve markedly.According to theory framework, modeling methods and technological scheme mentioned above, an intelligent "the Web-Based Virtual Laboratory for Electric and Electronic Experiment", integrating with experiment teaching, experiment operationand experiment report, is constructed. In the VL, the instruments are developed as components, which improves the developing efficiency and the reusing of sofetware. The SPICE and digital chip model are used for simulating and computing in the server, which enhances the simulation capability, such as analog circuits, digital circuits and hybrid circuits of AD (analog & digital). Compared with other simulation software of electronic circuits, this system achieves excellent performance in designability, arbitrariness of operation and interaction with sense of reality. In the VL, users can "connect" electronic circuits freely using various kinds of "virtual components and apparatus" in the realistic multimedia "virtual scene", and can also receive the simulation result in real time via the "measure" of the corresponding "virtual instruments", which makes users operate it with great interest just like doing real experiments and gains good effect in experimental teaching.The creative points of this thesis lie in: (1) A Mi-structure model and modeling methods of virtual experiment is proposed, and a reusable implementation method based on class template is provided; (2) A SPICE-based algorithm for analog circuit simulation is proposed. The algorithm, using the SPICE3f5 as the simulation model, realizes the emulational experiment for analog circuits under the virtual environment via the interface program; (3) A digital chip-based algorithm for digital circuit simulation is proposed, which realizes the emulational experiment for digital circuits and hybrid of AD under the virtual environment via the methods of recursion and back-tracking; (4) A scheme of integration of simulation technology and multimedia technolog is proposed, which realizes technological sharing and integrating for multi-developing platform with COM components.