In this paper,a security defense issue is investigated for networked control systems susceptible to stochastic denial of service(DoS) attacks by using the sliding mode control method.To utilize network communication r...In this paper,a security defense issue is investigated for networked control systems susceptible to stochastic denial of service(DoS) attacks by using the sliding mode control method.To utilize network communication resources more effectively,a novel adaptive event-triggered(AET) mechanism is introduced,whose triggering coefficient can be adaptively adjusted according to the evolution trend of system states.Differing from existing event-triggered(ET) mechanisms,the proposed one demonstrates exceptional relevance and flexibility.It is closely related to attack probability,and its triggering coefficient dynamically adjusts depending on the presence or absence of an attack.To leverage attacker information more effectively,a switching-like sliding mode security controller is designed,which can autonomously select different controller gains based on the sliding function representing the attack situation.Sufficient conditions for the existence of the switching-like sliding mode secure controller are presented to ensure the stochastic stability of the system and the reachability of the sliding surface.Compared with existing time-invariant control strategies within the triggered interval,more resilient defense performance can be expected since the correlation with attack information is established in both the proposed AET scheme and the control strategy.Finally,a simulation example is conducted to verify the effectiveness and feasibility of the proposed security control method.展开更多
Research on teacher talk has shown that many different teaching behaviors between native speaking teachers and nonnative speaking teachers may result from their different English proficiency.This paper aims to examine...Research on teacher talk has shown that many different teaching behaviors between native speaking teachers and nonnative speaking teachers may result from their different English proficiency.This paper aims to examine the differences between Australian English teachers(AETs)and Chinese English teachers(CETs)in language classrooms in terms of language use,linguistic complexity,linguistic variety.Two college teachers(one AET and one CET)were observed.Data were collected via classroom observation and analyzed by a qualitative research method.The findings revealed that there were certain differences in the above aspects.The results,therefore,have implications for language teaching.展开更多
基金supported in part by Shanghai Natural Science Foundation(24ZR1454700)the National Natural Science Foundation of China(62503331,62533016,62573279,62173231,62203288)Shanghai Pujiang Program(23PJD033)。
文摘In this paper,a security defense issue is investigated for networked control systems susceptible to stochastic denial of service(DoS) attacks by using the sliding mode control method.To utilize network communication resources more effectively,a novel adaptive event-triggered(AET) mechanism is introduced,whose triggering coefficient can be adaptively adjusted according to the evolution trend of system states.Differing from existing event-triggered(ET) mechanisms,the proposed one demonstrates exceptional relevance and flexibility.It is closely related to attack probability,and its triggering coefficient dynamically adjusts depending on the presence or absence of an attack.To leverage attacker information more effectively,a switching-like sliding mode security controller is designed,which can autonomously select different controller gains based on the sliding function representing the attack situation.Sufficient conditions for the existence of the switching-like sliding mode secure controller are presented to ensure the stochastic stability of the system and the reachability of the sliding surface.Compared with existing time-invariant control strategies within the triggered interval,more resilient defense performance can be expected since the correlation with attack information is established in both the proposed AET scheme and the control strategy.Finally,a simulation example is conducted to verify the effectiveness and feasibility of the proposed security control method.
文摘Research on teacher talk has shown that many different teaching behaviors between native speaking teachers and nonnative speaking teachers may result from their different English proficiency.This paper aims to examine the differences between Australian English teachers(AETs)and Chinese English teachers(CETs)in language classrooms in terms of language use,linguistic complexity,linguistic variety.Two college teachers(one AET and one CET)were observed.Data were collected via classroom observation and analyzed by a qualitative research method.The findings revealed that there were certain differences in the above aspects.The results,therefore,have implications for language teaching.
