Nickel oxide(NiO)hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling,hydrothermal reaction and calcination.The prepared NiO hollow microspheres composed of...Nickel oxide(NiO)hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling,hydrothermal reaction and calcination.The prepared NiO hollow microspheres composed of many nanoflakes,are about 2-3μm in diameter.The length of the NiO flakes,having clear edges,is about 500-700 nm,while the thickness is only about 40-50 nm.This indicates that the NiO microspheres possess a hierarchical structure that can provide porous channels to facilitate the transmission of both electrons and electrolyte ions.NiO microspheres exhibit a high specific capacitance of about 1340 F/g at a current density of 1 A/g and high capacitance retention about 96.5%after 1000 cycles.What’s more,the conductive mechanism of nickel oxide for electrochemical capacitor electrodes was also studied.展开更多
For rate control (RC) of hierarchical structure coding, an independent rate-quantization (R-Q) model was proposed based on mean absolute differences (MADs) in different temporal levels (TLs). In the proposed R-Q model...For rate control (RC) of hierarchical structure coding, an independent rate-quantization (R-Q) model was proposed based on mean absolute differences (MADs) in different temporal levels (TLs). In the proposed R-Q model, a novel MAD model was developed according to the hierarchical structure. The experimental results demonstrate that the proposed algorithm provides better performance, in terms of average peak signal-to-noise ratio (PSNR) and quality smoothness, than the H.264 reference model, JM14.2, under various sequences.展开更多
In this paper, the issue of actuator-structure interaction in dynamic testing of structures is considered. The problem is approached from the novel standpoint of impedance control. It is shown that an effective strate...In this paper, the issue of actuator-structure interaction in dynamic testing of structures is considered. The problem is approached from the novel standpoint of impedance control. It is shown that an effective strategy to design controls for dynamic testing is by designing the test system impedance. It is also shown that this can be achieved using feedforward compensation. The analysis is carried out in the context of displacement controlled dynamic testing, when the tested structure has a high and nonlinear stiffness. It is demonstrated that stable and accurate dynamic testing can be achieved using the proposed strategy, when this is not possible using traditional feedback control techniques. Furthermore, the impedance control and feedforward strategies are applied in the context of hybrid simulation, a technique of coupling computational and physical substructures applied in earthquake engineering. Here, a delay compensation scheme is necessary in addition to feedforward. Experimental results are presented that demonstrate both improved dynamic testing performance when impedance control is employed, and its applicability in hybrid simulation.展开更多
TCSC的阻抗控制是实现TCSC其他控制功能的基础。为更好地实现TCSC对命令阻抗的响应,采用了一种新型阻抗控制策略——小脑模型神经网络(Cerebella Model Articulation Controller,CMAC)与PID复合控制策略。该控制策略能够实现被控对象的...TCSC的阻抗控制是实现TCSC其他控制功能的基础。为更好地实现TCSC对命令阻抗的响应,采用了一种新型阻抗控制策略——小脑模型神经网络(Cerebella Model Articulation Controller,CMAC)与PID复合控制策略。该控制策略能够实现被控对象的逆动态模型,同时保证系统能有效地抑制扰动,具有足够的稳定性。在Matlab/Simulink仿真环境下搭建两区域四机系统进行仿真,结果证实了该控制策略的有效性。展开更多
基于交直流系统潮流方程雅可比矩阵的特征结构分析法,提出了一种利用可控串联补偿器(thyristor controlled series compensator,TCSC)提高交直流系统静态电压稳定性的方法。该方法研究了交直流系统潮流方程雅可比矩阵的最小模特征值,以...基于交直流系统潮流方程雅可比矩阵的特征结构分析法,提出了一种利用可控串联补偿器(thyristor controlled series compensator,TCSC)提高交直流系统静态电压稳定性的方法。该方法研究了交直流系统潮流方程雅可比矩阵的最小模特征值,以节点电压对无功功率变化的灵敏度为指标,结合参与因子,判断全电网中最有可能发生电压不稳定的节点或者区域,从而为系统无功功率补偿装置的配置提供决策依据。对美国西部5机14节点系统进行了仿真计算,验证了TCSC在交直流系统中提高静态电压稳定性的可行性、有效性和正确性。展开更多
现代电力系统中的各元件,如发电机与高压直流输电(high voltage direct current,HVDC)、柔性交流输电等电力电子装置,均安装有控制器,当进行区域控制(或进行区域级仿真或分析)时,迫切需要含各元件控制器的完整区域模型。该文系统给出规...现代电力系统中的各元件,如发电机与高压直流输电(high voltage direct current,HVDC)、柔性交流输电等电力电子装置,均安装有控制器,当进行区域控制(或进行区域级仿真或分析)时,迫切需要含各元件控制器的完整区域模型。该文系统给出规范化建立静止无功补偿器(static var compensator,SVC)、可控串联电容补偿器(thyristor controlled series capacitor,TCSC)与HVDC元件本身模型、含元件控制器在内的元件完整模型的方法,并给出在保证微分–代数性质、保留隐动态的前提下,降低微分方程阶数与复杂性的元件简化模型,从而得到相对比较简洁的包含SVC、TCSC与HVDC等电力电子装置本身及其控制器在内的区域模型。为实时控制提供合适的区域级模型,采用的控制器(原理上)能基本覆盖当前所应用的传统的线性控制器、复杂的(可解析表达的)非线性控制器,以及神经网络逆控制那样的非解析控制器。最后还对建立的简化模型与完整模型进行仿真试验对比,验证了简化方法的有效性。展开更多
基金Project(51274248)supported by the National Natural Science Foundation of ChinaProject(201FA31440)supported by the International S&T Cooperation Program of China
文摘Nickel oxide(NiO)hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling,hydrothermal reaction and calcination.The prepared NiO hollow microspheres composed of many nanoflakes,are about 2-3μm in diameter.The length of the NiO flakes,having clear edges,is about 500-700 nm,while the thickness is only about 40-50 nm.This indicates that the NiO microspheres possess a hierarchical structure that can provide porous channels to facilitate the transmission of both electrons and electrolyte ions.NiO microspheres exhibit a high specific capacitance of about 1340 F/g at a current density of 1 A/g and high capacitance retention about 96.5%after 1000 cycles.What’s more,the conductive mechanism of nickel oxide for electrochemical capacitor electrodes was also studied.
基金National Natural Science Foundations of China (No. 60972035,No. 61074009)Natural Science Foundation Program of Shanghai,China ( No. 10ZR1432800)
文摘For rate control (RC) of hierarchical structure coding, an independent rate-quantization (R-Q) model was proposed based on mean absolute differences (MADs) in different temporal levels (TLs). In the proposed R-Q model, a novel MAD model was developed according to the hierarchical structure. The experimental results demonstrate that the proposed algorithm provides better performance, in terms of average peak signal-to-noise ratio (PSNR) and quality smoothness, than the H.264 reference model, JM14.2, under various sequences.
基金Dept.of Civil,Structural and Architectural Engineering and the College of Engineering and Applied Sciences of the University of Colorado at Boulder,USA
文摘In this paper, the issue of actuator-structure interaction in dynamic testing of structures is considered. The problem is approached from the novel standpoint of impedance control. It is shown that an effective strategy to design controls for dynamic testing is by designing the test system impedance. It is also shown that this can be achieved using feedforward compensation. The analysis is carried out in the context of displacement controlled dynamic testing, when the tested structure has a high and nonlinear stiffness. It is demonstrated that stable and accurate dynamic testing can be achieved using the proposed strategy, when this is not possible using traditional feedback control techniques. Furthermore, the impedance control and feedforward strategies are applied in the context of hybrid simulation, a technique of coupling computational and physical substructures applied in earthquake engineering. Here, a delay compensation scheme is necessary in addition to feedforward. Experimental results are presented that demonstrate both improved dynamic testing performance when impedance control is employed, and its applicability in hybrid simulation.
文摘TCSC的阻抗控制是实现TCSC其他控制功能的基础。为更好地实现TCSC对命令阻抗的响应,采用了一种新型阻抗控制策略——小脑模型神经网络(Cerebella Model Articulation Controller,CMAC)与PID复合控制策略。该控制策略能够实现被控对象的逆动态模型,同时保证系统能有效地抑制扰动,具有足够的稳定性。在Matlab/Simulink仿真环境下搭建两区域四机系统进行仿真,结果证实了该控制策略的有效性。
文摘基于交直流系统潮流方程雅可比矩阵的特征结构分析法,提出了一种利用可控串联补偿器(thyristor controlled series compensator,TCSC)提高交直流系统静态电压稳定性的方法。该方法研究了交直流系统潮流方程雅可比矩阵的最小模特征值,以节点电压对无功功率变化的灵敏度为指标,结合参与因子,判断全电网中最有可能发生电压不稳定的节点或者区域,从而为系统无功功率补偿装置的配置提供决策依据。对美国西部5机14节点系统进行了仿真计算,验证了TCSC在交直流系统中提高静态电压稳定性的可行性、有效性和正确性。
文摘现代电力系统中的各元件,如发电机与高压直流输电(high voltage direct current,HVDC)、柔性交流输电等电力电子装置,均安装有控制器,当进行区域控制(或进行区域级仿真或分析)时,迫切需要含各元件控制器的完整区域模型。该文系统给出规范化建立静止无功补偿器(static var compensator,SVC)、可控串联电容补偿器(thyristor controlled series capacitor,TCSC)与HVDC元件本身模型、含元件控制器在内的元件完整模型的方法,并给出在保证微分–代数性质、保留隐动态的前提下,降低微分方程阶数与复杂性的元件简化模型,从而得到相对比较简洁的包含SVC、TCSC与HVDC等电力电子装置本身及其控制器在内的区域模型。为实时控制提供合适的区域级模型,采用的控制器(原理上)能基本覆盖当前所应用的传统的线性控制器、复杂的(可解析表达的)非线性控制器,以及神经网络逆控制那样的非解析控制器。最后还对建立的简化模型与完整模型进行仿真试验对比,验证了简化方法的有效性。
