基于多领域建模的交互式虚拟实验调度机制
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摘要
当前各学科的虚拟教学实验系统的开发没有统一的标准,存在实现方法各异,扩展性差的问题。多领域统一建模方法为解决这个问题提供了很好的思路。然而,目前传统的多领域统一建模方法,如Modelica,主要是面向科学计算,实时交互性弱,无法满足虚拟教学实验的要求。同时统一的虚拟实验平台需要支持大量并发用户的访问,传统的多领域建模方法也未予以考虑。
基于多领域建模的交互式虚拟实验调度机制解决了多领域统一建模与实时虚拟教学实验的差异性问题。调度机制将仿真任务分解成多段连续时间的计算单元,并周期性的运行仿真任务,从而实现实时计算过程。同时在各计算单元中加入对用户响应的处理,来达到虚拟实验实时交互的目的。在对仿真任务进行调度时,周期性仿真任务步长算法控制每段周期运行的仿真任务的步长值,以达到提高系统吞吐率的目的。交互性仿真任务步长算法通过合理的设置对用户操作进行响应的仿真任务的步长值,以达到减少响应时间的目的。仿真过程中通过仿真频率来控制仿真任务周期性的运行。在实时调度算法中,通过计算出服务利用率来保证调度期间的服务质量。
系统测试表明,交互式虚拟实验调度机制能够实现虚拟实验的实时交互性,并且在高负载情况下,整个系统的吞吐率较传统仿真建模方法,提高了30%以上,保证了整个系统的服务质量。
Current development system of virtual educational experiment of various disciplines faces with the problems of no uniform standards, heterogeneous developing methods and poor scalability. Multi-domain unified modelling (MDUM) could provide the mentality to solve the above problems, However, at the present ,traditional MDUM (such as Modelica) is mainly targeted at scientific computing and lack of capability for supporting real-time interaction, which could not meet the requirements of virtual educational experiment. Moreover, uniform platform of virtual educational experiment should be capable of sup-porting massive concurrent user access, which is also not taken into consideration in tradi-tional MDUM.
The interactive scheduling mechanism of virtual experiment based on Modelica is used to solve the discrepancy between traditional MDUM and real-time virtual educational ex-periment. The scheduling mechanism splits the simulation task into multiple time-continuous computing units, and executes the simulation task periodically in order to achieve real-time computation. Besides, the handling process for user request is integrated into each computing unit to realize the purpose of real-time interaction in virtual experi-ment. Periodic simulation task scheduling algorithm is utilized to control the step of each simulation task in the scheduling, which could improve the throughput of system. Simula-tion step for user response is configured reasonably by interactive simulation task schedul-ing algorithm, which could yield shorter response time. And the scheduling mechanism controls the simulation circle by implementing simulation-frequency. In the real-time scheduling algorithm, the service utilization rate is calculated to guarantee service quality during the scheduling period.
System testing demonstrates that the interactive scheduling mechanism could meet the demand of real-time interaction in virtual experiment, and compared to the traditional MDUM, its throughput increased by 30 percent under high loading, which could guarantee service quality for the whole system.
基于多领域建模的交互式虚拟实验调度机制解决了多领域统一建模与实时虚拟教学实验的差异性问题。调度机制将仿真任务分解成多段连续时间的计算单元,并周期性的运行仿真任务,从而实现实时计算过程。同时在各计算单元中加入对用户响应的处理,来达到虚拟实验实时交互的目的。在对仿真任务进行调度时,周期性仿真任务步长算法控制每段周期运行的仿真任务的步长值,以达到提高系统吞吐率的目的。交互性仿真任务步长算法通过合理的设置对用户操作进行响应的仿真任务的步长值,以达到减少响应时间的目的。仿真过程中通过仿真频率来控制仿真任务周期性的运行。在实时调度算法中,通过计算出服务利用率来保证调度期间的服务质量。
系统测试表明,交互式虚拟实验调度机制能够实现虚拟实验的实时交互性,并且在高负载情况下,整个系统的吞吐率较传统仿真建模方法,提高了30%以上,保证了整个系统的服务质量。
Current development system of virtual educational experiment of various disciplines faces with the problems of no uniform standards, heterogeneous developing methods and poor scalability. Multi-domain unified modelling (MDUM) could provide the mentality to solve the above problems, However, at the present ,traditional MDUM (such as Modelica) is mainly targeted at scientific computing and lack of capability for supporting real-time interaction, which could not meet the requirements of virtual educational experiment. Moreover, uniform platform of virtual educational experiment should be capable of sup-porting massive concurrent user access, which is also not taken into consideration in tradi-tional MDUM.
The interactive scheduling mechanism of virtual experiment based on Modelica is used to solve the discrepancy between traditional MDUM and real-time virtual educational ex-periment. The scheduling mechanism splits the simulation task into multiple time-continuous computing units, and executes the simulation task periodically in order to achieve real-time computation. Besides, the handling process for user request is integrated into each computing unit to realize the purpose of real-time interaction in virtual experi-ment. Periodic simulation task scheduling algorithm is utilized to control the step of each simulation task in the scheduling, which could improve the throughput of system. Simula-tion step for user response is configured reasonably by interactive simulation task schedul-ing algorithm, which could yield shorter response time. And the scheduling mechanism controls the simulation circle by implementing simulation-frequency. In the real-time scheduling algorithm, the service utilization rate is calculated to guarantee service quality during the scheduling period.
System testing demonstrates that the interactive scheduling mechanism could meet the demand of real-time interaction in virtual experiment, and compared to the traditional MDUM, its throughput increased by 30 percent under high loading, which could guarantee service quality for the whole system.
引文
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[29] Ling Y X, Liao H X, Shi X N, et al. Design and Implement on SimGrid-HLA about Simulation Grid Prototype. Journal of Simulation System, 2005, 17 (12): 2953~2956
[30] Chandrasekaran S, Silver G, Miller J A, et al. XML-based Modeling and Simulation: Web Service Technologies and Their Synergy with Simulation. In: Snowdon J L, Charnes J M, Eds. Proceedings of the 34th Conference on Winter Simulation: Ex-ploring New Frontiers. San Diego, California. 2002. San Diego: IEEE Computer So-ciety, 2002. 606~615
[31] Dunston P S, Wang X. Mixed Reality based-Visualization Interfaces for Architecture, Engineering, and Construction Industry. Journal of Construction Engineering and Management, 2005, 131(12): 1301~1309
[32] Colwell C, Scanlon E, Cooper M. Using Remote Laboratories to Extend Access to Science and Engineering. Computer and Education, 2002, 38(1-3): 65~76
[33] Benetazzo L, Bertocco M, Ferraris F, et al. A Web-based Distributed Virtual Educa-tional Laboratory. IEEE Transaction on Instrumentation and Measurement, 2000, 49 (2): 349~356
[34] Nickerson J V, Corter J E, Esche S K, et al. A Model for Evaluating the Effectiveness of Remote Engineering Laboratories and Simulations in Education. Computers and Education, 2007, 49: 708~725
[35] Stein P R. The PumaPaint Project, Autonomous Robots. 2003, 15(3): 255~265
[36] Estrin D, Handley M, Heidemann J, et al. Network Visualization with Nam, the VINT Network Animator. Computer, 2000, 33(11):63~68
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[40]上官右黎,孙燕莲,文福安.电类课程网上虚拟实验系统的设计与开发.北京邮电大学学报社会科学版, 2005, 10(7):37~40
[41]义忠,刘敏,陈立平.多领域物理系统混合建模平台开发.计算机辅助设计与图形学学报, 2006, 18(1):120~124
[2] Zhong Y M, Shirinzadeh B. Analysis, Conversion and Visualization of Discrete Si-mulation Results. In: Proceedings of Eighth International Conference on Information Visualisation, IV 2004. London, UK: IEEE Computer Society, 2004. 118~123
[3] Higa M L, Tawy D M, Lord S M. An Introduction to LabVIEW Exercise for an Elec-tronics Class. Frontiers in Education, 2002: T1D-13~T1D-16
[4] Rathmell J, Sturrock D T. Arena: the Arena Product Family: Enterprise Modeling So-lutions. In: Proceedings of the 34th Conference on Winter Simulation. San Diego, California. 2002. 519~523
[5] Krahl D. The Extend Simulation Environment. In: Proceedings of 2002 Simulation Conference. 2002. 205~213
[6] Reilly JO. AweSim: Introduction to AweSim. In: Proceedings of the 34th Conference on Winter Simulation. San Diego, California: 2002. 221~224
[7] Akesson J, Ekman T, Hedin G. Development of a Modelica Compiler Using Jas-tAdd. Electronic Notes in Theoretical Computer Science, 2008,203(2):117~131
[8] Mattsson S E, Otter M, Elmqvist H. Realization of Web-based Simulation Services. Computers in Industry, 2006,57(3):261~271
[9] Fritzson P, Bunus P. Modelica - a General Object-oriented Language for Continuous and Discrete-event System Modeling and Simulation. In: Proceedings of 35th Annual Simulation Symposium. 2002.365~380
[10] Dwan T E, Bechert T E. Introducing SIMULINK into a Systems Engineering Curri-culum. In: Proceedings of 23th Annual Frontiers in Education Conference. 1993. 627~631
[11] Rohrer M. AutoMod Product Suite Tutorial (AutoMod, Simulator, AutoStat) by Au-toSimulations. In: Proceedings of Simulation Conference. 1999. 220~226
[12] Nordgren WB. Flexsim Simulation Environment. In: Proceedings of the Simulation Conference. 2002. 250~252
[13] Rajagopalan S, Sastry V V, Ajjarapu V, et al. Object-oriented Measurement Templates for Power Electronics Education and Research using DYMOLA (Dynamic Modeling Laboratory). In: Proceedings of the 7th Workshop on Computers in Power Electronics, 2000. 2000.166~171
[14] Knobel C, Janin G, Woodruff A. Development and Verification of a Series Car Mod-elica/ Dymola Multi-Body Model to Investigate Vehicle Dynamics Systems. In: Proceedings of 5th International Modelica Conference. Vienna, Austria: 2006. 167~176
[15] Li W, Abel A, Todtermuschke K, et al. Hybrid Vehicle Power Transmission Model-ing and Simulation with SimulationX. In: Proceedings of International Conference on Mechatronics and Automation, 2007. ICMA 2007. Link?ping, Sweden: 2007. 1710~1717
[16] Nytsch-Geusen C, Ernst T, Nordwig A, et al. Advanced Modeling and Simulation Techniques in MOSILAB: A System Development Case Study. In: Proceedings of the 5th International Modelica Conference. Vienna, Austria: Modelica Association and arsenal research, 2006. 63~71
[17] Lee D Y, Yun C, Cho A, et al. WebCell: a Web-based Environment for Kinetic Mod-eling and Dynamic Simulation of Cellular Networks. Bioinformatics, 2006, 220: 1150~1151
[18] Olivier B G, Snoep J L. Web-based Kinetic Modeling using JWS Online. Bioinfor-matics, 2004, 20: 2143~2144
[19] Ko C C, Chen B M, Chen S H, el al. A Large-scale Web-based Virtual Oscilloscope Laboratory Experiment. Engineering Science and Education, 2000, 9(2): 69~76
[20] Weiler M, McDonnell J J. Virtual Experiments: a New Approach for Improving Process Conceptualization in Hillslope Hydrology. Journal of Hydrology, 2004, 285: 3~18
[21] Claeys F, Chtepen M, Benedetti L, et al. Distributed Virtual Experiments in Water Quality Management. Water Science and Technology, 2006, 53(1):297~305
[22] Taradi S K, Taradi T, et al. Blending Problem-based Learning with Web Technology Positively Impacts Student Learning Outcomes in Acid-base Physiology. Advanced Physiology Education, 2005, 29: 35~39
[23] Gurkan D, Mickelson A, Benhaddou D. Remote Laboratories for Optical Circuits. IEEE Transactions on Education, 2008. 51(1): 53~60
[24] Ko C C, Chen B M, Chen J P, et al. Development of a Web-based Laboratory for Control Experients on a Coupled Tank Apparatus. IEEE Transactions on Education, 2001, 44: 76~86
[25] Krehbiel D, Zerger R, Piper J K. A Remote-Access LabVIEW-based Laboratory for Environmental and Ecological Science. International Journal of Engineering Educa-tion, 2003, 19: 495~502
[26] Miller J A, Seila A F, Xiang X. The JSIM Web-based Simulation Environment. Fu-ture Generation Computer Systems, 2000, 17 (2): 119~133
[27] Han H S. Web-based Dynamic Simulation System for Multi-body Systems. Advancesin Engineering Software, 2004, 35(2): 75~84
[28] He Q, Hao J G, Huang J. A Simulation Service System Based on SOA. Computer Simulation, 2007, 24 (5): 98~102
[29] Ling Y X, Liao H X, Shi X N, et al. Design and Implement on SimGrid-HLA about Simulation Grid Prototype. Journal of Simulation System, 2005, 17 (12): 2953~2956
[30] Chandrasekaran S, Silver G, Miller J A, et al. XML-based Modeling and Simulation: Web Service Technologies and Their Synergy with Simulation. In: Snowdon J L, Charnes J M, Eds. Proceedings of the 34th Conference on Winter Simulation: Ex-ploring New Frontiers. San Diego, California. 2002. San Diego: IEEE Computer So-ciety, 2002. 606~615
[31] Dunston P S, Wang X. Mixed Reality based-Visualization Interfaces for Architecture, Engineering, and Construction Industry. Journal of Construction Engineering and Management, 2005, 131(12): 1301~1309
[32] Colwell C, Scanlon E, Cooper M. Using Remote Laboratories to Extend Access to Science and Engineering. Computer and Education, 2002, 38(1-3): 65~76
[33] Benetazzo L, Bertocco M, Ferraris F, et al. A Web-based Distributed Virtual Educa-tional Laboratory. IEEE Transaction on Instrumentation and Measurement, 2000, 49 (2): 349~356
[34] Nickerson J V, Corter J E, Esche S K, et al. A Model for Evaluating the Effectiveness of Remote Engineering Laboratories and Simulations in Education. Computers and Education, 2007, 49: 708~725
[35] Stein P R. The PumaPaint Project, Autonomous Robots. 2003, 15(3): 255~265
[36] Estrin D, Handley M, Heidemann J, et al. Network Visualization with Nam, the VINT Network Animator. Computer, 2000, 33(11):63~68
[37] Rout P P, Emam K E, Fusani P, et al. SPICE in retrospect: Developing a Standard for Process Assessment. Journal of Systems and Software, 2007, 80(9):1483~1493
[38] Cheng Y M, Chen L S, Lin C H, et al. A Multimedia Teaching Case Learning System for Medical Education. In: Proceedings of World Conference on Educational Multi-media, Hypermedia & Telecommunications. Hawaii, USA: 2003(1). 369~372
[39] Kang Z, Evett M P. CyberLab: An Online Virtual Laboratory Toolkit for Non-Programmers. In: Proceedings of Eighth IEEE International Conference on Ad-vanced Learning Technologies. 2008. 316~318
[40]上官右黎,孙燕莲,文福安.电类课程网上虚拟实验系统的设计与开发.北京邮电大学学报社会科学版, 2005, 10(7):37~40
[41]义忠,刘敏,陈立平.多领域物理系统混合建模平台开发.计算机辅助设计与图形学学报, 2006, 18(1):120~124
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