Revisiting the Parallel Strategy for DOACROSS Loops

Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...     

Scalable Clock Synchronization Analysis: A Symmetric Noncooperative Output Feedback Tubes-MPC Approach

In the cyber-physical environment, the clock synchronization algorithm is required to have better expansion for network scale. In this paper, a new measurement model of observability under the equivalent transformation of minimum mean square error (MMSE) is constructed based on basic measurement unit (BMU), which can realize the scaled expansion of MMSE measurement. Based on the state updating equation of absolute clock and the decoupled measurement model of MMSE-like equivalence, which is proposed to calculate the positive definite invariant set by using the theoretical-practical Luenberger observer as the synthetical observer, the local noncooperative optimal control problem is built, and the clock synchronization system driven by the ideal state of local clock can reach the exponential convergence for synchronization performance. Different from the problem of general linear system regulators, the state estimation error and state control error are analyzed in the established affine system based on the set-theory-in-control to achieve the quantification of state deviation caused by noise interference. Based on the BMU for isomorphic state map, the synchronization performance of clock states between multiple sets of representative nodes is evaluated, and the scale of evaluated system can be still expanded. After the synchronization is completed, the state of perturbation system remains in the maximum range of measurement accuracy, and the state of nominal system can be stabilized at the ideal state for local clock and realizes the exponential convergence of the clock synchronization system.      

基于不可靠通信链路的数据共享模块

随着企业规模的逐步扩大和计算机网络与企业信息技术的飞速发展，大中型企业陆续建立了很多业务系统，对各个系统之间数据同步的安全性提出了更高的需求。针对此需求，基于RabbitMQ消息队列中间件，本文设计并实现基于不可靠通信链路的数据共享模块，解决在企业内部两级数据中心之间的双向数据同步问题，并通过RabbitMQ的消息确认机制和持久化机制，保证数据的安全送达、无丢失。经过实践证明，该数据共享模块功能稳定，可提高两级数据中心的数据传输效率并保证其安全性。     

摇篮式五坐标加工中心C轴转台旋转故障原因分析与处理

针对HS664RT,摇篮式五坐标加工中心力矩电动机驱动的C轴转台故障,介绍了故障排查、处理方法和力矩电动机相位角同步设置步骤。     

F-OFDM仿真系统设计与时频同步算法

针对新一代5G波形的F-OFDM技术开展了研究,通过把一个宽带分为若干个子带,对每个子带进行滤波处理以实现更好的通信效能。基于Simulink平台进行了F-OFDM仿真系统的搭建,重点对F-OFDM符号同步方法和频偏估计方法进行了研究与仿真分析。实验结果表明,基于Chu序列相比采用PN序列可以获得更好的同步效果,基于导频的Classen频偏估计算法相比基于CP的CFO估计算法和基于训练序列的Moose估计方法可以获得更好的频偏估计效果。     

一种新型随钻轨迹仪的研制

针对现有随钻轨迹仪工作时间短、需人工同步、"数钻杆"记录钻孔深度不足等问题,采用深度实时测量技术、电源智能管理技术和数据自动同步与成图等关键技术,研制了新型随钻轨迹仪。该仪器由直线位移传感器、压力传感器、霍尔开关等组成,具有钻孔深度自动测量、电源智能管理、测量数据与深度自动匹配等功能。试验结果表明:新型钻孔轨迹仪工作稳定可靠、无需人工干预、工作时间长、生产效率高。     

双永磁电机系统转速同步控制

针对双永磁同步电机系统中,由于负载扰动造成双电机转速不同步而极易引发差速振荡的问题,该文结合交叉耦合控制结构和滑模控制算法,提出一种基于积分型滑模速度控制器的转速同步控制策略,使用指数趋近律以及饱和函数抑制滑模固有的抖振现象。此外,设计了转速同步控制器对两电机的电流环进行补偿,通过选择合适的耦合同步系数,使两电机速度尽快达到同步。实验结果验证了在所提出的控制策略下,双永磁同步电机系统的鲁棒性、转速跟踪性能以及同步性能均得到提升。     

磁耦合谐振式无线电能传输系统功效同步研究

针对磁耦合谐振式无线电能传输系统中传输效率最大值与功率最大值难以同步的问题,利用等效电路理论对无线电能传输系统进行建模分析,给出系统传输效率最佳频率和传输功率最佳频率的计算方法,提出最佳谐振频率和功效同步因数的概念,得出系统传输效率与功率最大值同步出现的条件。借助仿真软件分析系统传输效率和功率与负载的变化规律,搭建实验平台,通过对比实验数据和仿真结果,证明了理论分析的正确性,也为进一步优化系统功效同步性能,同时提高传输效率和功率提供了有益的参考。     

基于CANopen协议的转台双电机同步控制

对CANopen协议进行了简单介绍,设计了一套基于CANopen协议的双电机同步控制系统。并在实验转台的俯仰轴上成功实现了基于CANopen的伺服控制。控制算法采用交叉耦合的控制。实验跟踪曲线为y=sin(0.1t),单电机控制和双电机控制的跟踪精度分别为0.298 0″和0.281 3″。结果表明,系统响应迅速,可靠性高,同步性好,满足设计要求。     

Distributed cooperative synchronization strategy for multi-bus microgrids

Microgrids can operate in both grid-connected mode and islanded mode. In order to smooth transfer from islanded mode to grid-connected mode, it is necessary to synchronize the point of common coupling (PCC) with main utility grid (UG) in voltage frequency, phase and amplitude. Conventional synchronization methods based on centralized communication are very costly and not suitable for multi-bus microgrids that have a large number of distributed generators (DGs). To address this concern, this study presents an active synchronization control strategy based on distributed cooperation technology for multi-bus microgrids. The proposed method can reconnect the microgrid in island to UG seamlessly with sparse communication channels. Synchronization correction signals are generated by a voltage controller, which are only transmitted to the leader DGs. Meanwhile, each DG exchanges information with its neighbors. Finally, the voltage of PCC will synchronize with the main grid and all DGs will achieve the consensus behaviors. Compared with traditional synchronization methods, the proposed method does not need complex communication networks and improves flexibility and redundancy. Even if the distributed communication breaks down, the primary droop control can still operate robustly. Small signal model of entire system is developed to adjust the parameters of distributed active synchronization controller. Simulation results are presented to verify the effectiveness of the proposed method.