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Verification of workflow nets with transition conditions
Zhao-xia Wang, Jian-min Wang, Xiao-chen Zhu, Li-jie Wen
Front. Inform. Technol. Electron. Eng., 2012, 13(7): 483-509.
https://doi.org/10.1631/jzus.C1100364
Workflow management is concerned with automated support for business processes. Workflow management systems are driven by process models specifying the tasks that need to be executed, the order in which they can be executed, which resources are authorised to perform which tasks, and data that is required for, and produced by, these tasks. As workflow instances may run over a sustained period of time, it is important that workflow specifications be checked before they are deployed. Workflow verification is usually concerned with control-flow dependencies only; however, transition conditions based on data may further restrict possible choices between tasks. In this paper we extend workflow nets where transitions have concrete conditions associated with them, called WTC-nets. We then demonstrate that we can determine which execution paths of a WTC-net that are possible according to the control-flow dependencies, are actually possible when considering the conditions based on data. Thus, we are able to more accurately determine at design time whether a workflow net with transition conditions is sound.
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A high performance simulation methodology for multilevel grid-connected inverters
Lu-jun Wang, Tao Yang, Da-min Zhang, Zheng-yu Lu
Front. Inform. Technol. Electron. Eng., 2012, 13(7): 544-551.
https://doi.org/10.1631/jzus.C1100315
To design a high reliability multilevel grid-connected inverter, a high performance simulation methodology based on Saber is proposed. The simulation methodology with optimized simulation speed can simulate the factors that have significant impacts on the stability and performance of the control system, such as digital delay, dead band, and the quantization error. The control algorithm in the simulation methodology is implemented using the C language, which facilitates the future porting to an actual system since most actual digital controllers are programmed in the C language. The modeling of the control system is focused mainly on diode-clamped three-level grid-connected inverters, and simulations for other topologies can be easily built based on this simulation. An example of designing a proportional-resonant (PR) controller with the aid of the simulation is introduced. The integer scaling effect in fixed-point digital signal processors (DSPs) on the control system is demonstrated and the performance of the controller is validated through experiments.
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Harmonic suppressed bandpass filter using composite right/left handed transmission line
Jian-gang Liang, He-xiu Xu
Front. Inform. Technol. Electron. Eng., 2012, 13(7): 552-558.
https://doi.org/10.1631/jzus.C1100386
A wideband composite right/left handed transmission line (CRLH TL) in conjunction with its corresponding equivalent circuit model is studied based on a cascaded complementary single split ring resonator (CCSSRR). The characterization is performed by theory analysis, circuit simulation, and full-wave electromagnetic (EM) simulation. The negative refractive index (NRI) and backward wave propagation performance of the CRLH TL are demonstrated. For application, a bandpass filter (BPF) with enhanced out-of-band selectivity and harmonic suppression operating at the wireless local area network (WLAN) band is designed, fabricated, and measured by combining the CRLH TL with a complementary electric inductive-capacitive resonator (CELC). Three CELC cells with wideband stopband performance in the conductor strip and ground plane, respectively, are utilized in terms of single negative permeability. The design concept has been verified by the measurement data.
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6 articles
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