针对面向对象软件在动态更新中遇到类型安全问题,定义了一个多版本类的动态更新演算(MCUFJ演算(multi-version class dynamic updamble calculus based on FJ calculus))来描述类动态更新.MCUFJ演算以FJ(featherweight Java)演算为核心...针对面向对象软件在动态更新中遇到类型安全问题,定义了一个多版本类的动态更新演算(MCUFJ演算(multi-version class dynamic updamble calculus based on FJ calculus))来描述类动态更新.MCUFJ演算以FJ(featherweight Java)演算为核心,通过增加update操作表示类的动态更新,运用多版本技术使动态更新可以在保持新旧对象共存的情况下完成,讨论了类的数据域和方法进行增加、删除、修改以及类型变化对程序类型安全性的影响,并且指出MCUFJ上类型安全的动态更新需要满足的约束.定义了类的可动态更新限制,并且证明了在该条件下多版本类的动态更新在类型上的安全性.该演算可以用于指导Java语言和面向对象程序语言的类动态更新.展开更多
常规慢速频移键控跳频（frequency-hopping/frequency-shift-keying,FH/FSK）受跟踪干扰威胁严重;差分跳频抗跟踪干扰能力强,但部分频带干扰下误码率高。为提高常规慢速跳频抗跟踪干扰性能,同时不损失抗部分频带干扰性能,提出的多序列...常规慢速频移键控跳频（frequency-hopping/frequency-shift-keying,FH/FSK）受跟踪干扰威胁严重;差分跳频抗跟踪干扰能力强,但部分频带干扰下误码率高。为提高常规慢速跳频抗跟踪干扰性能,同时不损失抗部分频带干扰性能,提出的多序列跳频（multi-sequence frequency hopping,MSFH）无线通信方式中,数据信道和补偿信道频率分别按不同跳频序列跳变,使干扰方无法准确跟踪补偿信道,减少了跟踪干扰影响;而接收机射频前端采用窄带接收,与差分跳频的宽带接收相比可有效抑制部分频带干扰。在瑞利衰落信道下,分析了卷积编码MSFH抗干扰性能。数值和仿真表明,在最坏跟踪干扰下MSFH比常规跳频约有5~10dB误码率性能增益,且抗部分频带干扰性能优于差分跳频。展开更多
In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal w...In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal with the difficulties associated with input saturation. An adaptive DSC design with an auxiliary first-order filter is used to solve the "explosion of complexity"problem. It is proved that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded, and the tracking error eventually converges to a small neighborhood around zero. The main advantage of the proposed method is that only one adaptation parameter needs to be updated,which reduces the computational burden significantly. Simulation results demonstrate the feasibility of the proposed scheme and the comparison results show that the improved DSC method can reduce the computational burden by almost two thirds in comparison with the standard DSC method.展开更多
文摘针对面向对象软件在动态更新中遇到类型安全问题,定义了一个多版本类的动态更新演算(MCUFJ演算(multi-version class dynamic updamble calculus based on FJ calculus))来描述类动态更新.MCUFJ演算以FJ(featherweight Java)演算为核心,通过增加update操作表示类的动态更新,运用多版本技术使动态更新可以在保持新旧对象共存的情况下完成,讨论了类的数据域和方法进行增加、删除、修改以及类型变化对程序类型安全性的影响,并且指出MCUFJ上类型安全的动态更新需要满足的约束.定义了类的可动态更新限制,并且证明了在该条件下多版本类的动态更新在类型上的安全性.该演算可以用于指导Java语言和面向对象程序语言的类动态更新.
文摘常规慢速频移键控跳频（frequency-hopping/frequency-shift-keying,FH/FSK）受跟踪干扰威胁严重;差分跳频抗跟踪干扰能力强,但部分频带干扰下误码率高。为提高常规慢速跳频抗跟踪干扰性能,同时不损失抗部分频带干扰性能,提出的多序列跳频（multi-sequence frequency hopping,MSFH）无线通信方式中,数据信道和补偿信道频率分别按不同跳频序列跳变,使干扰方无法准确跟踪补偿信道,减少了跟踪干扰影响;而接收机射频前端采用窄带接收,与差分跳频的宽带接收相比可有效抑制部分频带干扰。在瑞利衰落信道下,分析了卷积编码MSFH抗干扰性能。数值和仿真表明,在最坏跟踪干扰下MSFH比常规跳频约有5~10dB误码率性能增益,且抗部分频带干扰性能优于差分跳频。
基金supported in part by the National Natural Science Foundation of China (61773051,61773072,61761166011)the Fundamental Research Fund for the Central Universities (2016RC021,2017JBZ003)
文摘In this paper, we propose an adaptive fuzzy dynamic surface control(DSC) scheme for single-link flexible-joint robotic systems with input saturation. A smooth function is utilized with the mean-value theorem to deal with the difficulties associated with input saturation. An adaptive DSC design with an auxiliary first-order filter is used to solve the "explosion of complexity"problem. It is proved that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded, and the tracking error eventually converges to a small neighborhood around zero. The main advantage of the proposed method is that only one adaptation parameter needs to be updated,which reduces the computational burden significantly. Simulation results demonstrate the feasibility of the proposed scheme and the comparison results show that the improved DSC method can reduce the computational burden by almost two thirds in comparison with the standard DSC method.
