Weighted priority queueing is a modification of priority queueing that eliminates the possibility of blocking lower priority traffic. The weights assigned to priority classes determine the fractions of the bandwith th...Weighted priority queueing is a modification of priority queueing that eliminates the possibility of blocking lower priority traffic. The weights assigned to priority classes determine the fractions of the bandwith that are guaranteed for individual traffic classes, similarly as in weighted fair queueing. The paper describes a timed Petri net model of weighted priority queueing and uses discrete-event simulation of this model to obtain performance characteristics of simple queueing systems. The model is also used to analyze the effects of finite queue capacity on the performance of queueing systems.展开更多
With the rapid development of various applications of Information Technology,big data are increasingly generated by social network services(SNS)nowadays.The designers and providers of SNS distribute different client a...With the rapid development of various applications of Information Technology,big data are increasingly generated by social network services(SNS)nowadays.The designers and providers of SNS distribute different client applications for PC,Mobile phone,IPTV etc.,so that users can obtain related service via mobile or traditional Internet.Good scalability and considerably short time delay are important indices for evaluating social network systems.As a result,investigating and mining the principle of users’behaviors is an important issue which can guide service providers to establish optimal systems with SNS.On the basis of analyzing the characteristics of social network system,this paper constructed a Stochastic Petri Net(SPN)model for describing the behaviors of three users for SNS.Moreover,the scalability of users’behaviors of SNS was studied by extending the SPN model of three users to the one of four users.Furthermore,average time delay was chosen as the performance index to evaluate the performance of these two constructed SPN models with Stochastic Petri Net Package(SPNP)6.0.For different parameters of number of connections,traffic load and buffer size,various trends and numerical results are derived thereby.The methodology of modeling and simulation in this paper can be further used to study the performance of SNS.展开更多
The integrated modular avionics （IMA） architecture is an open standard in avionics industry, in which the number of functionalities implemented by software is greater than ever before. In the IMA architecture, the r...The integrated modular avionics （IMA） architecture is an open standard in avionics industry, in which the number of functionalities implemented by software is greater than ever before. In the IMA architecture, the reliability of the avionics system is highly affected by the software applications. In order to enhance the fault tolerance feature with regard to software application failures, many industrial standards propose a layered health monitoring/fault management （HM/FM） scheme to periodically check the health status of software application processes and recover the malfunctioning software process whenever an error is located. In this paper, we make an analytical study of the HM/FM system for avionics application software. We use the stochastic Petri nets （SPN） to build a formal model of each component and present a method to combine the components together to form a complete system model with respect to three interlayer query strategies. We further investigate the effectiveness of these strategies in an illustrative system.展开更多
文摘Weighted priority queueing is a modification of priority queueing that eliminates the possibility of blocking lower priority traffic. The weights assigned to priority classes determine the fractions of the bandwith that are guaranteed for individual traffic classes, similarly as in weighted fair queueing. The paper describes a timed Petri net model of weighted priority queueing and uses discrete-event simulation of this model to obtain performance characteristics of simple queueing systems. The model is also used to analyze the effects of finite queue capacity on the performance of queueing systems.
基金supported by the Excellent Young Teachers Training Project (the second level,Project Number:YXJS201508)Teaching reform projects of Communication University of China (Project Number:JG190033,Project Number:JG22062).
文摘With the rapid development of various applications of Information Technology,big data are increasingly generated by social network services(SNS)nowadays.The designers and providers of SNS distribute different client applications for PC,Mobile phone,IPTV etc.,so that users can obtain related service via mobile or traditional Internet.Good scalability and considerably short time delay are important indices for evaluating social network systems.As a result,investigating and mining the principle of users’behaviors is an important issue which can guide service providers to establish optimal systems with SNS.On the basis of analyzing the characteristics of social network system,this paper constructed a Stochastic Petri Net(SPN)model for describing the behaviors of three users for SNS.Moreover,the scalability of users’behaviors of SNS was studied by extending the SPN model of three users to the one of four users.Furthermore,average time delay was chosen as the performance index to evaluate the performance of these two constructed SPN models with Stochastic Petri Net Package(SPNP)6.0.For different parameters of number of connections,traffic load and buffer size,various trends and numerical results are derived thereby.The methodology of modeling and simulation in this paper can be further used to study the performance of SNS.
基金supported by the National Grand Fundamental Research Program of China (Nos. 2010CB328105, 2009CB320504)the Tsinghua University Initiative Scientific Research Programthe National Natural Science Foundation of China (Nos. 61070182,60973107, 60973144, 61173008, 61070021)
文摘The integrated modular avionics （IMA） architecture is an open standard in avionics industry, in which the number of functionalities implemented by software is greater than ever before. In the IMA architecture, the reliability of the avionics system is highly affected by the software applications. In order to enhance the fault tolerance feature with regard to software application failures, many industrial standards propose a layered health monitoring/fault management （HM/FM） scheme to periodically check the health status of software application processes and recover the malfunctioning software process whenever an error is located. In this paper, we make an analytical study of the HM/FM system for avionics application software. We use the stochastic Petri nets （SPN） to build a formal model of each component and present a method to combine the components together to form a complete system model with respect to three interlayer query strategies. We further investigate the effectiveness of these strategies in an illustrative system.
