In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and ...In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and then increase the unit output.However,restricted by the low temperature of waste flue gas,the energy-saving efect is inconspicuous.Based on the common waste heat utilization system of the flue gas.展开更多
An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is c...An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear two- point boundary value （TPBV） problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.展开更多
Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firs...Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firstly,the mechanical parameters of each rock group were identified from the experimental data; secondly,the rheological calculation and analysis for the cavern in stepped excavation without supporting were made; finally,the optimal time for supporting at the characteristic point in a typical section was obtained while the creep rate and displacement after each excavation step has satisfied the criterion of the optimal supporting time. Excavation was repeated when the optimal time for supporting was identified,and the long-term stability creep time and the maximum creep deformation of the characteristic point were determined in accordance with the criterion of long-term stability index. It is shown that the optimal supporting time of the characteristic point in the underground plant of Xiangjiaba hydro-power station is 5-8 d,the long-term stability time of the typical section is 126 d,and the corresponding largest creep deformation is 24.30 mm. While the cavern is supported,the cavern deformation is significantly reduced and the stress states of the surrounding rock masses are remarkably improved.展开更多
Considering the flexible attitude maneuver and the narrow field of view of agile Earth observation satellite(AEOS)together,a comprehensive task clustering(CTC)is proposed to improve the observation scheduling problem ...Considering the flexible attitude maneuver and the narrow field of view of agile Earth observation satellite(AEOS)together,a comprehensive task clustering(CTC)is proposed to improve the observation scheduling problem for AEOS(OSPFAS).Since the observation scheduling problem for AEOS with comprehensive task clustering(OSWCTC)is a dynamic combination optimization problem,two optimization objectives,the loss rate(LR)of the image quality and the energy consumption(EC),are proposed to format OSWCTC as a bi-objective optimization model.Harnessing the power of an adaptive large neighborhood search(ALNS)algorithm with a nondominated sorting genetic algorithm II(NSGA-II),a bi-objective optimization algorithm,ALNS+NSGA-II,is developed to solve OSWCTC.Based on the existing instances,the efficiency of ALNS+NSGA-II is analyzed from several aspects,meanwhile,results of extensive computational experiments are presented which disclose that OSPFAS considering CTC produces superior outcomes.展开更多
A mathematical approach was proposed to investigate the impact of high penetration of large-scale photovoltaic park(LPP) on small-signal stability of a power network and design of hybrid controller for these units.A s...A mathematical approach was proposed to investigate the impact of high penetration of large-scale photovoltaic park(LPP) on small-signal stability of a power network and design of hybrid controller for these units.A systematic procedure was performed to obtain the complete model of a multi-machine power network including LPP.For damping of oscillations focusing on inter-area oscillatory modes,a hybrid controller for LPP was proposed.The performance of the suggested controller was tested using a 16-machine 5-area network.The results indicate that the proposed hybrid controller for LPP provides sufficient damping to the low-frequency modes of power system for a wide range of operating conditions.The method presented in this work effectively indentifies the impact of increased PV penetration and its controller on dynamic performance of multi-machine power network containing LPP.Simulation results demonstrate that the model presented can be used in designing of essential controllers for LPP.展开更多
以北京市四惠枢纽为研究对象,探索以数据驱动为导向满足乘客需求的枢纽动态导向标识方案评估及优化设计方法。首先,搭建KANO乘客需求模型,通过桌面实验,形成动态导向标识在内容、样式及空间位置上的优化设计方案,与四惠枢纽现有方案形...以北京市四惠枢纽为研究对象,探索以数据驱动为导向满足乘客需求的枢纽动态导向标识方案评估及优化设计方法。首先,搭建KANO乘客需求模型,通过桌面实验,形成动态导向标识在内容、样式及空间位置上的优化设计方案,与四惠枢纽现有方案形成对比。其次,基于寻路理论通过建筑信息建模(building information modeling,BIM)+虚拟现实(virtual reality,VR)仿真技术,实现人与枢纽的信息交互,提取新旧导向标识方案作用下乘客寻路过程的特征参数。最后,通过对寻路实验中主客观指标分析可知,被试在新版动态导向标识方案中寻路时间、犯错误点数及迷茫点数显著降低,且新版动态导向标识方案在内容、样式及空间位置上满意度均优于旧版。结果表明:研究搭建BIM+VR的虚拟仿真平台,形成以数据驱动为导向的枢纽动态导向标识方案综合评估及优化设计方法,为枢纽动态导向标识方案设计及合理应用提供技术与理论支撑。展开更多
文摘In common,the waste heat of the flue gas is recovered and utilized to heat the low temperature feedwater by installing the low temperature economizer(LTE),which can save the steam extracted from the steam turbine and then increase the unit output.However,restricted by the low temperature of waste flue gas,the energy-saving efect is inconspicuous.Based on the common waste heat utilization system of the flue gas.
基金supported by the National Natural Science Foundation of China(60574023)the Natural Science Foundation of Shandong Province(Z2005G01).
文摘An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear two- point boundary value （TPBV） problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.
基金Projects(50911130366, 50979030) supported by the National Natural Science Foundation of ChinaProject(2008BAB29B01) supported by the National Key Technology R&D Program of China
文摘Numerical analysis of the optimal supporting time and long-term stability index of the surrounding rocks in the underground plant of Xiangjiaba hydro-power station was carried out based on the rheological theory. Firstly,the mechanical parameters of each rock group were identified from the experimental data; secondly,the rheological calculation and analysis for the cavern in stepped excavation without supporting were made; finally,the optimal time for supporting at the characteristic point in a typical section was obtained while the creep rate and displacement after each excavation step has satisfied the criterion of the optimal supporting time. Excavation was repeated when the optimal time for supporting was identified,and the long-term stability creep time and the maximum creep deformation of the characteristic point were determined in accordance with the criterion of long-term stability index. It is shown that the optimal supporting time of the characteristic point in the underground plant of Xiangjiaba hydro-power station is 5-8 d,the long-term stability time of the typical section is 126 d,and the corresponding largest creep deformation is 24.30 mm. While the cavern is supported,the cavern deformation is significantly reduced and the stress states of the surrounding rock masses are remarkably improved.
文摘Considering the flexible attitude maneuver and the narrow field of view of agile Earth observation satellite(AEOS)together,a comprehensive task clustering(CTC)is proposed to improve the observation scheduling problem for AEOS(OSPFAS).Since the observation scheduling problem for AEOS with comprehensive task clustering(OSWCTC)is a dynamic combination optimization problem,two optimization objectives,the loss rate(LR)of the image quality and the energy consumption(EC),are proposed to format OSWCTC as a bi-objective optimization model.Harnessing the power of an adaptive large neighborhood search(ALNS)algorithm with a nondominated sorting genetic algorithm II(NSGA-II),a bi-objective optimization algorithm,ALNS+NSGA-II,is developed to solve OSWCTC.Based on the existing instances,the efficiency of ALNS+NSGA-II is analyzed from several aspects,meanwhile,results of extensive computational experiments are presented which disclose that OSPFAS considering CTC produces superior outcomes.
文摘A mathematical approach was proposed to investigate the impact of high penetration of large-scale photovoltaic park(LPP) on small-signal stability of a power network and design of hybrid controller for these units.A systematic procedure was performed to obtain the complete model of a multi-machine power network including LPP.For damping of oscillations focusing on inter-area oscillatory modes,a hybrid controller for LPP was proposed.The performance of the suggested controller was tested using a 16-machine 5-area network.The results indicate that the proposed hybrid controller for LPP provides sufficient damping to the low-frequency modes of power system for a wide range of operating conditions.The method presented in this work effectively indentifies the impact of increased PV penetration and its controller on dynamic performance of multi-machine power network containing LPP.Simulation results demonstrate that the model presented can be used in designing of essential controllers for LPP.
文摘以北京市四惠枢纽为研究对象,探索以数据驱动为导向满足乘客需求的枢纽动态导向标识方案评估及优化设计方法。首先,搭建KANO乘客需求模型,通过桌面实验,形成动态导向标识在内容、样式及空间位置上的优化设计方案,与四惠枢纽现有方案形成对比。其次,基于寻路理论通过建筑信息建模(building information modeling,BIM)+虚拟现实(virtual reality,VR)仿真技术,实现人与枢纽的信息交互,提取新旧导向标识方案作用下乘客寻路过程的特征参数。最后,通过对寻路实验中主客观指标分析可知,被试在新版动态导向标识方案中寻路时间、犯错误点数及迷茫点数显著降低,且新版动态导向标识方案在内容、样式及空间位置上满意度均优于旧版。结果表明:研究搭建BIM+VR的虚拟仿真平台,形成以数据驱动为导向的枢纽动态导向标识方案综合评估及优化设计方法,为枢纽动态导向标识方案设计及合理应用提供技术与理论支撑。
