When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control （OLPC） technology has to be adopted to enrich the target signal interference ratio （S...When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control （OLPC） technology has to be adopted to enrich the target signal interference ratio （Silt） and improve the system performance. The existing problems about DS-CDMA outer loop power control for multi-service are introduced and the power control theoretical model is analyzed. System simulation is adopted on how to obtain the theoretical performance and parameter optimization of the power control algorithm. The OLPC algorithm is improved and the performance comparisons between the old algorithm and the improved algorithm are given. The results show good performance of the improved OLPC algorithm and prove the validity of the improved method for multi-service.展开更多
In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardwar...In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardware construction, is introduced. Spinning experiments show that the system achieves satisfactory result. This system can solve the diftkultles of mechatronical fusion between domestic hollow splndk fancy yarn spuming muchine and its microcomputer control technology.展开更多
Very high frequency(VHF) photocathode guns have excellent performance and are being increasingly selected as electron sources for high-repetition-rate X-ray free-electron lasers. As a highly loaded quality factor cavi...Very high frequency(VHF) photocathode guns have excellent performance and are being increasingly selected as electron sources for high-repetition-rate X-ray free-electron lasers. As a highly loaded quality factor cavity, the VHF gun requires high stability in the amplitude and phase of the cavity field. However, the gun is microwave powered by two solid-state power sources through two separate power couplers. The input difference between the two power couplers will influence the stability of the cavity field. To systematically study this influence and obtain measurement formulae, a multi-port VHF gun LCR circuit model is built and analyzed. During the warm-up condition, the cavity structure will be deformed due to the large-scale change in the cavity temperature. Then, the deformation will result in cavity resonant frequency changes. To prevent the mechanic tuner from suffering damages due to the frequent and long-distance movement for correcting the cavity resonant frequency, a self-excited loop(SEL) control system is considered for changing the loop phase and make the loop frequency follow the resonant frequency. In this study, a steady-state model of the VHF gun cavity is built for obtaining the optimal input coupler coefficient and the stability requirement of the forward voltage. Then, the generator-driven resonator and SEL control system, which combine with the VHF multiport modeling, are modeled and simulated. The simulated results show that the SEL system can perfectly operate in the process of condition and warm-up.展开更多
空间站在轨组装和长期运营阶段涉及到多飞行器独立飞行、飞行器间交会对接、多飞行器组合体融合控制、多飞行器分离过程控制和飞行器返回再入等复杂飞行任务,完整、真实的飞行模拟是必需且至关重要的.基于时间同步、实时数据交换的分布...空间站在轨组装和长期运营阶段涉及到多飞行器独立飞行、飞行器间交会对接、多飞行器组合体融合控制、多飞行器分离过程控制和飞行器返回再入等复杂飞行任务,完整、真实的飞行模拟是必需且至关重要的.基于时间同步、实时数据交换的分布式一体化仿真架构,设计了一种多飞行器协同的通用半物理制导、导航与控制(guidance,navigation and control,GNC)系统飞行模拟平台,可很好地满足复杂系统的飞行模拟需要.平台由若干灵活、可扩展的通用模拟器构成,单个模拟器通过配置可以实现任一飞行器的功能,能够独立对指定飞行器的全任务过程进行仿真.平台通过靶场仪器组B时间码(inter-range instramentation group-B,IRIG-B)信号进行时间同步,利用1553B总线完成动力学仿真数据实时交换,并在多模拟器之间通过协调机制实现热并网后进行协同仿真.该模拟平台成功应用于空间站飞行控制演练.展开更多
分析了Buck-Boost(反极性开关调节器)变换器的原理,指出了电压型、电流型、V2型等多种控制方法的优点和不足。为了达到更好的控制效果,在此基础上提出了多环控制方法,并对其进行了分析研究。介绍了其工作原理,建立了器件模型,用Matlab的...分析了Buck-Boost(反极性开关调节器)变换器的原理,指出了电压型、电流型、V2型等多种控制方法的优点和不足。为了达到更好的控制效果,在此基础上提出了多环控制方法,并对其进行了分析研究。介绍了其工作原理,建立了器件模型,用Matlab的Power System Blockset工具箱对该模型进行了仿真,将仿真结果与传统的控制方法进行比较,结果表明多环控制的动态特性好于传统的控制方法,从而验证了分析的正确性。展开更多
单载波码分与频分多址(SC-CFDMA,single carrier code and frequency division multiple access)体制要求符号定时精确至码片级,同步难度高于普通体制。为此提出一种多速率星地闭环同步方法,通过适当提升部分环路元件的控制速率,在环路...单载波码分与频分多址(SC-CFDMA,single carrier code and frequency division multiple access)体制要求符号定时精确至码片级,同步难度高于普通体制。为此提出一种多速率星地闭环同步方法,通过适当提升部分环路元件的控制速率,在环路非采样点上延续闭环控制,从而提高对用户运动速度的适应能力。推导了控制速率提升后相关元件及环路的状态空间方程,进行了Matlab软件仿真,结果表明,即使在高轨卫星通信场景下,所提方法也能将多个超音速用户之间的SC-CFDMA上行符号定时偏差同步至码片宽度内,保证链路畅通。展开更多
基金the National Natural Science Foundation of China (60532030).
文摘When a new user accesses the CDMA system, the load will change drastically, and therefore, the advanced outer loop power control （OLPC） technology has to be adopted to enrich the target signal interference ratio （Silt） and improve the system performance. The existing problems about DS-CDMA outer loop power control for multi-service are introduced and the power control theoretical model is analyzed. System simulation is adopted on how to obtain the theoretical performance and parameter optimization of the power control algorithm. The OLPC algorithm is improved and the performance comparisons between the old algorithm and the improved algorithm are given. The results show good performance of the improved OLPC algorithm and prove the validity of the improved method for multi-service.
文摘In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardware construction, is introduced. Spinning experiments show that the system achieves satisfactory result. This system can solve the diftkultles of mechatronical fusion between domestic hollow splndk fancy yarn spuming muchine and its microcomputer control technology.
文摘Very high frequency(VHF) photocathode guns have excellent performance and are being increasingly selected as electron sources for high-repetition-rate X-ray free-electron lasers. As a highly loaded quality factor cavity, the VHF gun requires high stability in the amplitude and phase of the cavity field. However, the gun is microwave powered by two solid-state power sources through two separate power couplers. The input difference between the two power couplers will influence the stability of the cavity field. To systematically study this influence and obtain measurement formulae, a multi-port VHF gun LCR circuit model is built and analyzed. During the warm-up condition, the cavity structure will be deformed due to the large-scale change in the cavity temperature. Then, the deformation will result in cavity resonant frequency changes. To prevent the mechanic tuner from suffering damages due to the frequent and long-distance movement for correcting the cavity resonant frequency, a self-excited loop(SEL) control system is considered for changing the loop phase and make the loop frequency follow the resonant frequency. In this study, a steady-state model of the VHF gun cavity is built for obtaining the optimal input coupler coefficient and the stability requirement of the forward voltage. Then, the generator-driven resonator and SEL control system, which combine with the VHF multiport modeling, are modeled and simulated. The simulated results show that the SEL system can perfectly operate in the process of condition and warm-up.
文摘空间站在轨组装和长期运营阶段涉及到多飞行器独立飞行、飞行器间交会对接、多飞行器组合体融合控制、多飞行器分离过程控制和飞行器返回再入等复杂飞行任务,完整、真实的飞行模拟是必需且至关重要的.基于时间同步、实时数据交换的分布式一体化仿真架构,设计了一种多飞行器协同的通用半物理制导、导航与控制(guidance,navigation and control,GNC)系统飞行模拟平台,可很好地满足复杂系统的飞行模拟需要.平台由若干灵活、可扩展的通用模拟器构成,单个模拟器通过配置可以实现任一飞行器的功能,能够独立对指定飞行器的全任务过程进行仿真.平台通过靶场仪器组B时间码(inter-range instramentation group-B,IRIG-B)信号进行时间同步,利用1553B总线完成动力学仿真数据实时交换,并在多模拟器之间通过协调机制实现热并网后进行协同仿真.该模拟平台成功应用于空间站飞行控制演练.
文摘分析了Buck-Boost(反极性开关调节器)变换器的原理,指出了电压型、电流型、V2型等多种控制方法的优点和不足。为了达到更好的控制效果,在此基础上提出了多环控制方法,并对其进行了分析研究。介绍了其工作原理,建立了器件模型,用Matlab的Power System Blockset工具箱对该模型进行了仿真,将仿真结果与传统的控制方法进行比较,结果表明多环控制的动态特性好于传统的控制方法,从而验证了分析的正确性。
文摘单载波码分与频分多址(SC-CFDMA,single carrier code and frequency division multiple access)体制要求符号定时精确至码片级,同步难度高于普通体制。为此提出一种多速率星地闭环同步方法,通过适当提升部分环路元件的控制速率,在环路非采样点上延续闭环控制,从而提高对用户运动速度的适应能力。推导了控制速率提升后相关元件及环路的状态空间方程,进行了Matlab软件仿真,结果表明,即使在高轨卫星通信场景下,所提方法也能将多个超音速用户之间的SC-CFDMA上行符号定时偏差同步至码片宽度内,保证链路畅通。
