异地站点之间需要在广域范围实现时间同步。除了采用卫星授时外,希望借助SDH(Synchronous Digital Hierarchy)网络进行时间同步性能的在线监测。但是广域范围内的SDH网络结构复杂、跳数较多,且大量存在上下行线路不对称的现象,对传统网...异地站点之间需要在广域范围实现时间同步。除了采用卫星授时外,希望借助SDH(Synchronous Digital Hierarchy)网络进行时间同步性能的在线监测。但是广域范围内的SDH网络结构复杂、跳数较多,且大量存在上下行线路不对称的现象,对传统网络时间同步技术提出了挑战。因此,针对广域SDH网络,提出了基于WR PTP(White Rabbit Precision Timing Protocol)技术的链路模型。该模型考虑了SDH网络中存在的各个延时环节及其计算方法,并针对实际网络中存在的不对称链路时延,给出了修正方法,推导了时钟偏差的修正计算公式。同时对于SDH环网中存在的链路倒换问题,给出了工程化解决方法。所提各方法在实际的SDH网络上进行了测试,结果表明,能达到的时间同步误差不超过1μs,可满足广域时间同步及时钟同步性能在线监测的需要。展开更多
针对目前广播电视同步数字体系(Synchronous Digital Hierarchy,SDH)微波传输系统部分电路设备老化、故障率高等现实问题,对现有SDH数字微波传输系统进行网际互连协议(Internet Protocol,IP)化升级改造,提出一套切实可行的实施方案,阐...针对目前广播电视同步数字体系(Synchronous Digital Hierarchy,SDH)微波传输系统部分电路设备老化、故障率高等现实问题,对现有SDH数字微波传输系统进行网际互连协议(Internet Protocol,IP)化升级改造,提出一套切实可行的实施方案,阐述方案设计思路、实施方法和注意事项等内容。通过项目实践充分验证了所提方案能够大幅降低电路设备故障率,提升微波传输的效率,充分保障广播电视节目的安全传输。展开更多
针对同步数字体系(Synchronous Digital Hierarchy,SDH)光纤通信系统在长期运行中易发生链路衰耗、光器件性能退化及时钟同步异常的问题,从系统结构与功能单元入手,系统分析典型故障类型及其成因,提出相应维护策略。该策略在缩短链路定...针对同步数字体系(Synchronous Digital Hierarchy,SDH)光纤通信系统在长期运行中易发生链路衰耗、光器件性能退化及时钟同步异常的问题,从系统结构与功能单元入手,系统分析典型故障类型及其成因,提出相应维护策略。该策略在缩短链路定位时间、延长器件使用寿命、提高同步精度等方面取得了显著成效,有效提高了SDH光纤通信系统的运行可靠性与维护效率。展开更多
Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot ...Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.展开更多
同步数字体系(Synchronous Digital Hierarchy,SDH)数字微波传输系统具有高效、稳定的特点,有利于实现高效的数据传输和可靠的通信.文中从SDH数字微波通信技术的优势入手,对载波键控技术、高速多状态调制解调技术、自适应交叉极化干扰...同步数字体系(Synchronous Digital Hierarchy,SDH)数字微波传输系统具有高效、稳定的特点,有利于实现高效的数据传输和可靠的通信.文中从SDH数字微波通信技术的优势入手,对载波键控技术、高速多状态调制解调技术、自适应交叉极化干扰抵消技术等进行了分析,希望能为相关领域的专业人士提供有益的参考,推动SDH数字微波传输技术的发展.展开更多
2020年,国家电网有限公司发布了相关文件,对5~8级通信设备事件的定义进行了调整,进一步提高了通信安全运行底线。为准确评估光传输网络的性能水平与面临的风险,优化并提升同步数字体系(Synchronous Digital Hierarchy,SDH)网络性能与可...2020年,国家电网有限公司发布了相关文件,对5~8级通信设备事件的定义进行了调整,进一步提高了通信安全运行底线。为准确评估光传输网络的性能水平与面临的风险,优化并提升同步数字体系(Synchronous Digital Hierarchy,SDH)网络性能与可靠性,进一步筑牢电力通信系统安全运行基础,文章提出了一种电力通信SDH网络风险评估体系。展开更多
This study investigates chaotic synchronization via field-coupled nonlinear circuits, achieving both electrical synchronization and energy balance. The driving mechanism biomimetically parallels neuromuscular signal t...This study investigates chaotic synchronization via field-coupled nonlinear circuits, achieving both electrical synchronization and energy balance. The driving mechanism biomimetically parallels neuromuscular signal transduction, where synchronized neuronal firing induces coordinated muscle contractions that produce macroscopic movement. We implement a Chua circuit-driven robotic arm with tunable periodic/chaotic oscillations through parameter modulation and external current injection. Bifurcation analysis maps oscillation modes under varying external stimuli. Inductive coupling between two systems with distinct initial conditions facilitates magnetic energy transfer, optimized by an energy balance criterion. A bio-inspired exponential gain method dynamically regulates the coupling strength to optimize the energy transfer efficiency.The effects of ambient electromagnetic noise on synchronization are systematically quantified. The results indicate electrically modulatable robotic arm dynamics, with the coupled systems achieving autonomous rapid synchronization. Despite noise-induced desynchronization, inter-system errors rapidly decay and stabilize within bounded limits, confirming robust stability.展开更多
BACKGROUND Cardiac myxoma is a benign neoplasm and one of the most common types of primary cardiac tumors.Synchronous cardiac myxoma and other malignancies are extremely rare,and only limited cases have been reported....BACKGROUND Cardiac myxoma is a benign neoplasm and one of the most common types of primary cardiac tumors.Synchronous cardiac myxoma and other malignancies are extremely rare,and only limited cases have been reported.CASE SUMMARY We describe a young patient with newly diagnosed locally advanced laryngeal cancer,with a synchronous cardiac tumor detected on staging scans.An echocar-diogram showed the typical appearance of myxoma in the left atrium.Early cardiac surgery was performed in view of its obstructive features and post cardiac surgery recovery was uneventful.The patient was scheduled for subsequent oncological treatment for the laryngeal cancer.However,due to rapid progression of the advanced laryngeal malignancy,he was placed on supportive care.CONCLUSION To our knowledge,this is the first reported case of synchronous cardiac myxoma with laryngeal malignancy.Individualized treatment strategy should be adopted to manage synchronous tumors in a multidisciplinary approach.The most life-threatening condition needs be treated first.Single resection,staged operations or simultaneous resection of both tumors have been reported with good outcomes.展开更多
Permanent-magnet synchronous machines(PMSMs)are widely used in robotics,rail transportation,and electric vehicles owing to their high power density,high efficiency,and high power factor.However,PMSMs often operate in ...Permanent-magnet synchronous machines(PMSMs)are widely used in robotics,rail transportation,and electric vehicles owing to their high power density,high efficiency,and high power factor.However,PMSMs often operate in harsh environments,where critical components such as windings and permanent magnets(PMs)are susceptible to failures.These faults can lead to a significant degradation in performance,posing substantial challenges to the reliable operation of PMSMs.This paper presents a comprehensive review of common fault types in PMSMs,along with their corresponding fault diagnosis and fault-tolerant control strategies.The underlying mechanisms of typical faults are systematically analyzed,followed by a detailed comparison of various diagnostic and fault-tolerant control methods to evaluate their respective advantages and limitations.Finally,the review concludes by identifying key research gaps in PMSM fault diagnosis and fault-tolerant control,while proposing potential future directions for advancing this field.展开更多
The blisk is a core component of an aero-engine,and electrochemical machining(ECM)is the primary method for its manufacture.Among several ECM methods for blisks,multi-tool synchronous machining is the most efficient a...The blisk is a core component of an aero-engine,and electrochemical machining(ECM)is the primary method for its manufacture.Among several ECM methods for blisks,multi-tool synchronous machining is the most efficient and advantageous for machining channels.The allowance distribution of the blank after blisk channel machining directly influences the blade profile accuracy.This paper proposes a trajectory control strategy to homogenize the allowance distribution of the blisk channel in multi-tool ECM.The strategy includes the design of the three-dimensional space motion of the tool and blisk,as well as the regulated feed speed.The structural characteristics of the blisk channel and the principle of ECM allow for designing and optimizing the multidimensional trajectory.The electric field simulations elucidate the influence law of the three-axis feed speed on the side gap.An algorithm is adopted to iteratively optimize the speeds for different positions to realize multi-dimensional motion control and allowance homogenization.The proposed trajectory control strategy is applied to ECM experiments for the blisk channel.Compared with the constant feed speed mode,the regulated speed strategy reduces the maximum allowance difference between the convex(CV)profiles by 36.18%and that between the concave(CC)profiles by 37.73%.Subsequently,the one-time ECM of eight blisk channels was successfully realized.The average time for a single channel was 12.5 min,significantly improving the machining efficiency.In conclusion,the proposed method is effective and can be extended for synchronously machining various blisk types with twisted channels.展开更多
针对继电保护信号在同步数字体系(synchronous digital hierarchy,SDH)传输中存在时延大、光电转换节点多、故障排除困难等问题,提出了一种基于2.048 Mbps速率的光接口传输继电保护信号的方法。通过在SDH传输设备中嵌入2M光接口板并与...针对继电保护信号在同步数字体系(synchronous digital hierarchy,SDH)传输中存在时延大、光电转换节点多、故障排除困难等问题,提出了一种基于2.048 Mbps速率的光接口传输继电保护信号的方法。通过在SDH传输设备中嵌入2M光接口板并与继电保护装置直连,利用SDH传输网络实现远距离电力线路继电保护信号的可靠传输。测试结果表明,该方法有效弥补了传统技术的不足,简化了网络结构,提高了传输效率。展开更多
文摘针对目前广播电视同步数字体系(Synchronous Digital Hierarchy,SDH)微波传输系统部分电路设备老化、故障率高等现实问题,对现有SDH数字微波传输系统进行网际互连协议(Internet Protocol,IP)化升级改造,提出一套切实可行的实施方案,阐述方案设计思路、实施方法和注意事项等内容。通过项目实践充分验证了所提方案能够大幅降低电路设备故障率,提升微波传输的效率,充分保障广播电视节目的安全传输。
文摘针对同步数字体系(Synchronous Digital Hierarchy,SDH)光纤通信系统在长期运行中易发生链路衰耗、光器件性能退化及时钟同步异常的问题,从系统结构与功能单元入手,系统分析典型故障类型及其成因,提出相应维护策略。该策略在缩短链路定位时间、延长器件使用寿命、提高同步精度等方面取得了显著成效,有效提高了SDH光纤通信系统的运行可靠性与维护效率。
文摘Permanent magnet synchronous motor(PMSM),known for their compact size and high-power density,is widely used in fields such as electric vehicles and servo drives.However,traditional PID control methods for PMSM cannot dynamically adjust parameters according to varying operating conditions.To address this issue,this paper proposes a PID control method based on a radial basis function(RBF)neural network,which adaptively tunes the PID controller parameters.First,an offline RBF neural network with optimal structural parameters is trained using the current and speed data of the PMSM,and then employed to construct the RBF-PID controller.During online training,the Jacobian information calculated via the RBF neural network is used to adaptively adjust the PID parameters.Simultaneously,the structural parameters of the RBF network are updated in reverse based on the error between the predicted and reference speed values.Finally,numerical simulations and experiments in the context of electric vehicle drive control show that the maximum speed errors of the SMC controller and the RBF-PID controller are 1.97 km/h and 0.17 km/h,respectively.Moreover,the RBF-PID controller outperforms both the SMC and traditional PID controllers in handling sudden speed changes.
文摘同步数字体系(Synchronous Digital Hierarchy,SDH)数字微波传输系统具有高效、稳定的特点,有利于实现高效的数据传输和可靠的通信.文中从SDH数字微波通信技术的优势入手,对载波键控技术、高速多状态调制解调技术、自适应交叉极化干扰抵消技术等进行了分析,希望能为相关领域的专业人士提供有益的参考,推动SDH数字微波传输技术的发展.
文摘2020年,国家电网有限公司发布了相关文件,对5~8级通信设备事件的定义进行了调整,进一步提高了通信安全运行底线。为准确评估光传输网络的性能水平与面临的风险,优化并提升同步数字体系(Synchronous Digital Hierarchy,SDH)网络性能与可靠性,进一步筑牢电力通信系统安全运行基础,文章提出了一种电力通信SDH网络风险评估体系。
基金Project supported by the National Key R&D Program of China (Grant No. 2023YFD2000601-02)。
文摘This study investigates chaotic synchronization via field-coupled nonlinear circuits, achieving both electrical synchronization and energy balance. The driving mechanism biomimetically parallels neuromuscular signal transduction, where synchronized neuronal firing induces coordinated muscle contractions that produce macroscopic movement. We implement a Chua circuit-driven robotic arm with tunable periodic/chaotic oscillations through parameter modulation and external current injection. Bifurcation analysis maps oscillation modes under varying external stimuli. Inductive coupling between two systems with distinct initial conditions facilitates magnetic energy transfer, optimized by an energy balance criterion. A bio-inspired exponential gain method dynamically regulates the coupling strength to optimize the energy transfer efficiency.The effects of ambient electromagnetic noise on synchronization are systematically quantified. The results indicate electrically modulatable robotic arm dynamics, with the coupled systems achieving autonomous rapid synchronization. Despite noise-induced desynchronization, inter-system errors rapidly decay and stabilize within bounded limits, confirming robust stability.
文摘BACKGROUND Cardiac myxoma is a benign neoplasm and one of the most common types of primary cardiac tumors.Synchronous cardiac myxoma and other malignancies are extremely rare,and only limited cases have been reported.CASE SUMMARY We describe a young patient with newly diagnosed locally advanced laryngeal cancer,with a synchronous cardiac tumor detected on staging scans.An echocar-diogram showed the typical appearance of myxoma in the left atrium.Early cardiac surgery was performed in view of its obstructive features and post cardiac surgery recovery was uneventful.The patient was scheduled for subsequent oncological treatment for the laryngeal cancer.However,due to rapid progression of the advanced laryngeal malignancy,he was placed on supportive care.CONCLUSION To our knowledge,this is the first reported case of synchronous cardiac myxoma with laryngeal malignancy.Individualized treatment strategy should be adopted to manage synchronous tumors in a multidisciplinary approach.The most life-threatening condition needs be treated first.Single resection,staged operations or simultaneous resection of both tumors have been reported with good outcomes.
基金supported by National Natural Science Foundation of China under Project 52437003 and 52421004in part by the National Key R&D Program of China under Project 2023YFB3406000in part by Heilongjiang Provincial Natural Science Foundation under Project YQ2022E029.
文摘Permanent-magnet synchronous machines(PMSMs)are widely used in robotics,rail transportation,and electric vehicles owing to their high power density,high efficiency,and high power factor.However,PMSMs often operate in harsh environments,where critical components such as windings and permanent magnets(PMs)are susceptible to failures.These faults can lead to a significant degradation in performance,posing substantial challenges to the reliable operation of PMSMs.This paper presents a comprehensive review of common fault types in PMSMs,along with their corresponding fault diagnosis and fault-tolerant control strategies.The underlying mechanisms of typical faults are systematically analyzed,followed by a detailed comparison of various diagnostic and fault-tolerant control methods to evaluate their respective advantages and limitations.Finally,the review concludes by identifying key research gaps in PMSM fault diagnosis and fault-tolerant control,while proposing potential future directions for advancing this field.
基金co-supported by the National Natural Science Foundation of China(No.52075253)the National Natural Science Foundation of China for Creative Research Groups(No.51921003)the Industrial Technology Development Program(No.JCKY2021605B026)。
文摘The blisk is a core component of an aero-engine,and electrochemical machining(ECM)is the primary method for its manufacture.Among several ECM methods for blisks,multi-tool synchronous machining is the most efficient and advantageous for machining channels.The allowance distribution of the blank after blisk channel machining directly influences the blade profile accuracy.This paper proposes a trajectory control strategy to homogenize the allowance distribution of the blisk channel in multi-tool ECM.The strategy includes the design of the three-dimensional space motion of the tool and blisk,as well as the regulated feed speed.The structural characteristics of the blisk channel and the principle of ECM allow for designing and optimizing the multidimensional trajectory.The electric field simulations elucidate the influence law of the three-axis feed speed on the side gap.An algorithm is adopted to iteratively optimize the speeds for different positions to realize multi-dimensional motion control and allowance homogenization.The proposed trajectory control strategy is applied to ECM experiments for the blisk channel.Compared with the constant feed speed mode,the regulated speed strategy reduces the maximum allowance difference between the convex(CV)profiles by 36.18%and that between the concave(CC)profiles by 37.73%.Subsequently,the one-time ECM of eight blisk channels was successfully realized.The average time for a single channel was 12.5 min,significantly improving the machining efficiency.In conclusion,the proposed method is effective and can be extended for synchronously machining various blisk types with twisted channels.
文摘针对继电保护信号在同步数字体系(synchronous digital hierarchy,SDH)传输中存在时延大、光电转换节点多、故障排除困难等问题,提出了一种基于2.048 Mbps速率的光接口传输继电保护信号的方法。通过在SDH传输设备中嵌入2M光接口板并与继电保护装置直连,利用SDH传输网络实现远距离电力线路继电保护信号的可靠传输。测试结果表明,该方法有效弥补了传统技术的不足,简化了网络结构,提高了传输效率。
