The design and realization of a videoconference system based on international recommendation are introduced in this paper, and the hardware implementation of video codec based on ITU-T H. 261 is briefly discussed. Fur...The design and realization of a videoconference system based on international recommendation are introduced in this paper, and the hardware implementation of video codec based on ITU-T H. 261 is briefly discussed. Furthermore, the buffer control method and the adaptive control strategy for quantization are proposed, which are adaptive and robust. This system can be operated under the transmission rate ranging from 128kb/s to 2Mb/s. With these strategies for the videoconference system, the high quality image is obtained. The time delay of the system is about half a second.展开更多
为标定光交叉芯片驱动电压,控制光交叉芯片实现光路由功能,提出并搭建了基于多通道DAC(Digital to Analog Converter)阵列的控制驱动电路系统。系统主要由控制系统模块、多路驱动电路模块及上位机控制模块构成。控制电路和驱动电路具有...为标定光交叉芯片驱动电压,控制光交叉芯片实现光路由功能,提出并搭建了基于多通道DAC(Digital to Analog Converter)阵列的控制驱动电路系统。系统主要由控制系统模块、多路驱动电路模块及上位机控制模块构成。控制电路和驱动电路具有调校简单、可双极性输出、输出路数多、加电精确度较高的特点,解决了当前驱动电路工作繁琐、加电极性单一、加电路数少、精度差的问题。上位机控制模块除了可控制驱动电路施加控制电压外,还可接收来自数据采集装置采集到的光功率信号作为控制驱动系统的反馈信号。通过分析控制电压与光功率之间的关系,可得到最佳的光交叉芯片控制驱动电压。系统测试实验结果表明,该系统能提供高精确度的双极性驱动电压,有效地对光交叉芯片进行驱动。可在较短的时间内标定出光开关的控制电压,完全可以满足有源光交叉芯片控制中对驱动电压的需求。该系统在光交叉芯片控制方面具有一定的应用价值。展开更多
This paper mainly discusses the following problems: the important meaning and special function of simulation system; the definition, contents and relationship of system and system simulation science; the definition an...This paper mainly discusses the following problems: the important meaning and special function of simulation system; the definition, contents and relationship of system and system simulation science; the definition and technology of simulation system and its equipments; and systematic description and exploration in relation to the developing trend of system simulation science and simulation system technology.展开更多
In this paper, the output tracking control is investigated for a class of nonlinear systems when only output is available for feedback. Based on the multivariable analog of circle criterion, an observer is first intro...In this paper, the output tracking control is investigated for a class of nonlinear systems when only output is available for feedback. Based on the multivariable analog of circle criterion, an observer is first introduced. Then, the observer-based output tracking controller is constructively designed by using the integral backstepping approach together with completing square. It is shown that, under relatively mild conditions, all the closed-loop signals are uniformly bounded. Meanwhile the system output asymptotically tracks the desired output. A simulation example is given to illustrate the effectiveness of the theoretical results.展开更多
The digital proportion control is introduced to improve the performance of the analog adaptive interference cancellation system （ICS）. For the high frequency parts of the signals after multiplier are not required,th...The digital proportion control is introduced to improve the performance of the analog adaptive interference cancellation system （ICS）. For the high frequency parts of the signals after multiplier are not required,the sampling frequency need not satisfy the sampling theorem for high frequency. Because the sampling,calculation and output expend time in digital control,the ideal condition,delay condition and delay-wait condition are taken into account. Through analyzing the system model with three conditions,we gain the stable conditions of the system,the optimization step factors that can make the system converge fastest and the formulas of the interference cancellation ratios （ICRs）. One step convergence can be accomplished under ideal condition,whereas the system can not converge in one step under delay condition and delay-wait condition. The calculation results show the convergence speed of delay-wait condition is slower than that of delay condition. The ICR is improved with the increase of the step factor which is in stable bound,but the convergence speed is decreased if the step factor exceeds the optimization step factor. In order to avoid that confine,the method of amending the steady state weight to improve the ICR is proposed. The analyses are in agreement with the computer simulations.展开更多
基金the High Technology Research and Development Programme of China
文摘The design and realization of a videoconference system based on international recommendation are introduced in this paper, and the hardware implementation of video codec based on ITU-T H. 261 is briefly discussed. Furthermore, the buffer control method and the adaptive control strategy for quantization are proposed, which are adaptive and robust. This system can be operated under the transmission rate ranging from 128kb/s to 2Mb/s. With these strategies for the videoconference system, the high quality image is obtained. The time delay of the system is about half a second.
文摘为标定光交叉芯片驱动电压,控制光交叉芯片实现光路由功能,提出并搭建了基于多通道DAC(Digital to Analog Converter)阵列的控制驱动电路系统。系统主要由控制系统模块、多路驱动电路模块及上位机控制模块构成。控制电路和驱动电路具有调校简单、可双极性输出、输出路数多、加电精确度较高的特点,解决了当前驱动电路工作繁琐、加电极性单一、加电路数少、精度差的问题。上位机控制模块除了可控制驱动电路施加控制电压外,还可接收来自数据采集装置采集到的光功率信号作为控制驱动系统的反馈信号。通过分析控制电压与光功率之间的关系,可得到最佳的光交叉芯片控制驱动电压。系统测试实验结果表明,该系统能提供高精确度的双极性驱动电压,有效地对光交叉芯片进行驱动。可在较短的时间内标定出光开关的控制电压,完全可以满足有源光交叉芯片控制中对驱动电压的需求。该系统在光交叉芯片控制方面具有一定的应用价值。
文摘This paper mainly discusses the following problems: the important meaning and special function of simulation system; the definition, contents and relationship of system and system simulation science; the definition and technology of simulation system and its equipments; and systematic description and exploration in relation to the developing trend of system simulation science and simulation system technology.
基金This work was supported by the National Natural Science Foundation of China(No.60304002), and the Science and Technical Development Plan ofShandong Province(No.2004GG4204014).
文摘In this paper, the output tracking control is investigated for a class of nonlinear systems when only output is available for feedback. Based on the multivariable analog of circle criterion, an observer is first introduced. Then, the observer-based output tracking controller is constructively designed by using the integral backstepping approach together with completing square. It is shown that, under relatively mild conditions, all the closed-loop signals are uniformly bounded. Meanwhile the system output asymptotically tracks the desired output. A simulation example is given to illustrate the effectiveness of the theoretical results.
文摘The digital proportion control is introduced to improve the performance of the analog adaptive interference cancellation system （ICS）. For the high frequency parts of the signals after multiplier are not required,the sampling frequency need not satisfy the sampling theorem for high frequency. Because the sampling,calculation and output expend time in digital control,the ideal condition,delay condition and delay-wait condition are taken into account. Through analyzing the system model with three conditions,we gain the stable conditions of the system,the optimization step factors that can make the system converge fastest and the formulas of the interference cancellation ratios （ICRs）. One step convergence can be accomplished under ideal condition,whereas the system can not converge in one step under delay condition and delay-wait condition. The calculation results show the convergence speed of delay-wait condition is slower than that of delay condition. The ICR is improved with the increase of the step factor which is in stable bound,but the convergence speed is decreased if the step factor exceeds the optimization step factor. In order to avoid that confine,the method of amending the steady state weight to improve the ICR is proposed. The analyses are in agreement with the computer simulations.
