| Web based virtual laboratory learning system is to build up a visualized experimentenvironment on network in order to carry out experimental lectures through Internet.This learning system overcomes location limits in traditional face-to-face learning mode,and extends experimental classroom to any place through Internet. The virtuallaboratory system will greatly simplify the operation course of the experiment, will savethe costs of use of different instruments in the experiment, realize the electrification ofthe experimental data, has broken the traditional restraint on region space and time oflaboratory.Nowadays, web based long-distance learning system for classroom instruction hasbecome more and more mature. However, web based long-distance learning system forexperiment instruction is still to be developed. This paper is based on computertechnology of the multimedia, network technology, fictitious instrument technology,have put forward the idea of carrying on the fictitious experiment on the net, namelyreplace the hardware with the software, use programming simulate the whole course ofthe experiment . And provide a set of the proper technological solutions of constructionof virtual laboratory, taking 8253 experiments in " interface technology of the computer" as an example, the careful analysis the whole course of development of Web basedvirtual laboratory learning system, thus verified the feasibility of this set of brand-newsolutions. This paper finishes the following task mainly:1). This subject has briefly introduced the development and application situation ofdistance learning at first, afterwards explained the production and domestic andinternational state of development of virtual experiment and virtual laboratory, andaccording to the concrete conditions of the laboratory at present, putting forward thenecessity and meaning of the studying of this subject.2). This paper analyses and compares with the characteristic of Client/Server andBrowser/Server, two kinds of network structure, this system selects Browser/Servermode finally. In some aspects, such as dependability, privacy, stepping the flatcharacteristic , software putting in an position , etc., it fit well according to the demandsof Web based virtual laboratory. 3). Through to the analysis of several key technology of the virtual laboratory bothat home and abroad, and the computation of various kinds of popular technology andsoftware tool at present, this paper put forward one brand-new solution, combinecontrolling part technology and ASP. NET technology together. In some aspects such assimplicity, flexibility, OO, type safe, development of virtual instrument, it hasadvantages than other technologies. 4). According to the design principle and goal of the Web based virtual laboratory,this paper has analyzed about function, module, system procedure of the system, etc,and take 8253 experiments in the interface experiment of the computer as an example,finish the development of the Web based virtual laboratory. And the draw line operationand the dynamic graphical display are difficult points of this system. This subject is not only an intact experimental system, but also a guide basicresearch, the purpose is to explore basic system structure of the virtual laboratorysystem, key technology, realize technology, design technology of virtual instrumentsand frame solution, in order to establishes the fundamental infrastructure to makeuniversities and institutes reach a new education level of computer technology,automobile engineering, machine-building, medical technology, etc. Network Virtual Laboratory system platform is composed of three modules,visualized virtual lab module, database management module and network servicemodule. Visualized virtual lab module is to provide virtual experiment environment forstudent to carry out experiments through client browser. Database management moduleis to manage student information and to guarantee system security. Network servicemodule is to provide network service. In this thesis, system platform of a web based long-distance virtual laboratory underMicrosoft Windows NT is presented on the basis of wide investigation and comparisonsinto researches about virtual experiment and virtual laboratory. System structure adoptsB/S network mode, and simulation of virtual experimental components are designed onthe basis of modern Virtual Reality theory. The key technologies used to realize thesemodules are as follows: Visualized virtual lab module: virtual experiment environment to provide courseware teaching system is developed on network by using HTML and ASP.NET technology. Visualized virtual instruments are developed on the basis of control technology and developing tool of Visual C#.NET. Database management system: courseware database is set up on the background supporter's database by using Microsoft SQL Server. Courseware management is set up on server to realize server inquiry using ADO.NET technology and to access websites built up by â…¡S. Network service module: all functions of network service are built up under integrated development environment of Microsoft Visual Studio.NET. It using the frame of B/S network, controller of Web technology. Client end can perform virtual experiments only through web browser. This text has been finally realized the experimental system of the 8253 timer/counter in "interface experiment of the computer". Four sub-modules in visualizedvirtual lab module, namely, user login and registration sub-module, hardware circuitsimulation sub-module, hardware program input sub-module and virtual oscillographsub-module to visualize experimental results on virtual oscillograph, are developed.User login and registration sub-module is to identify login information and to givepermission to access system. Cooperation of hardware circuit simulation sub-moduleand hardware program input sub-module is able to simulate hardware as virtualinstrument by using embedded software, to initialize hardware, to deal with hardwareprogram written in virtual environment, to extract digital control signal, and to realizevirtual experiments through web instead of experiments in real hardware environment.8253 timer/counter are key parts of changing the frequency signal into the digital signal,the working way of the counter, way of outputting are passed the online programmingby users, and then draw initial value and data control words by the system, submit to8253 virtual simulation software, calculate the result of output, show the picture incurve. In summary, this thesis presents a web based virtual laboratory learning system. The... |
