Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address the...Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address these issues.Utilizing five key technologies,the ECM effectively modulates radial stress post-excavation,redistributes stress in the surrounding rock,and eliminates tensile stress at the excavation face.Pre-tensioning measures further enhance the rock’s residual strength,establishing a new stability equilibrium.Field tests corroborate the method’s effectiveness,demonstrating a crown settlement reduction of 3–8 mm,a nearly 50%decrease compared to conventional construction approaches.Additionally,material consumption and construction duration were reduced by approximately 30%–35%and 1.75 months per 100 m,respectively.Thus,the ECM represents a significant innovation in enhancing the stability and construction efficiency of large-span rock tunnels,marking a novel contribution to the engineering field.展开更多
为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局...为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局部模振荡。第2个实例是就地补偿设计附加在静态同步补偿器（static synchronous compensator,STATCOM）上的稳定器,抑制多机电力系统中的区域模振荡,并给出在一个16机电力系统中的应用计算和仿真结果。展开更多
Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper ...Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.展开更多
目的:系统分析各类医生薪酬支付方式对医疗服务提供行为及结果的影响。方法:采用范畴综述法,以Web of Science和中国知网、维普及万方为数据源,“医生”“薪酬”“支付方式”和“医生行为”等为主题词,检索到相关文献2255篇,通过制定严...目的:系统分析各类医生薪酬支付方式对医疗服务提供行为及结果的影响。方法:采用范畴综述法,以Web of Science和中国知网、维普及万方为数据源,“医生”“薪酬”“支付方式”和“医生行为”等为主题词,检索到相关文献2255篇,通过制定严格的筛选程序最终纳入70篇相关研究。结果:按项目支付激励医生提供足量服务,但易导致过度医疗;固定薪水与按人头支付有助于控制成本,但易引发服务不足;DRG/DIP在医疗服务数量与质量方面的优势随患者病情加重而减弱。混合支付方式能够有效平衡医疗服务数量与成本,而按绩效支付在医疗质量提升方面总体表现突出。结论:医生薪酬单一支付方式难以实现医疗服务提供行为及结果最优化,且质量导向不足,多种支付方式与质量激励相融合的混合支付体系亟待构建。同时,建议深化医保结余薪酬转化机制改革,充分落实公立医院分配自主权,加快建立与医保支付和绩效考核协同的医生薪酬混合支付方式。展开更多
随着新能源发电比例越来越高,其受电网三相不平衡的影响越来越明显,尤其负序超标是导致电力系统安全性降低的重要原因。统一潮流控制器(unified power flow controller,UPFC)具有调节各序电流输出的能力,可用于提升系统的平衡性。为此,...随着新能源发电比例越来越高,其受电网三相不平衡的影响越来越明显,尤其负序超标是导致电力系统安全性降低的重要原因。统一潮流控制器(unified power flow controller,UPFC)具有调节各序电流输出的能力,可用于提升系统的平衡性。为此,首先建立基于解耦-补偿原理的UPFC正序最优补偿潮流算法;其次构建UPFC的负序补偿电流控制模型,将电压不平衡补偿的优化求解问题归结为凸二次约束二次规划(quadratically constrained quadratic programming,QCQP)问题,并采用原-对偶内点法求取UPFC的负序电流最优输出值;最后提出计及正序网损与负序电压指标的负序电压补偿最优潮流(optimal power flow,OPF)计算方法以及区域负序电压总体补偿策略。通过算例分析验证所提出方法的可行性与有效性。展开更多
为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和...为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和损耗模型,将齿槽转矩引起的系统转矩脉动作为扩展状态变量,与电流环的反馈电流一起构造系统扩张状态空间方程.在状态估计过程中引入了遗忘因子,提高观测精度和速度.与基于谐波电流注入法抑制齿槽转矩的控制方法进行了控制性能和突变工况对比.结果表明:所提出控制方法在低速时转矩脉动降低了43.5%,电损耗降低了14.8%,能更有效抑制齿槽转矩脉动和提高系统效率.展开更多
基金Projects(42377148,51674265)supported by the National Natural Science Foundation of ChinaProject(2018YFC0603705)supported by the National Key Research and Development Program of China。
文摘Engineering shallow,large-span rock tunnels challenges deformation control and escalates construction costs.This study investigates the excavation compensation method(ECM)and its associated technologies to address these issues.Utilizing five key technologies,the ECM effectively modulates radial stress post-excavation,redistributes stress in the surrounding rock,and eliminates tensile stress at the excavation face.Pre-tensioning measures further enhance the rock’s residual strength,establishing a new stability equilibrium.Field tests corroborate the method’s effectiveness,demonstrating a crown settlement reduction of 3–8 mm,a nearly 50%decrease compared to conventional construction approaches.Additionally,material consumption and construction duration were reduced by approximately 30%–35%and 1.75 months per 100 m,respectively.Thus,the ECM represents a significant innovation in enhancing the stability and construction efficiency of large-span rock tunnels,marking a novel contribution to the engineering field.
文摘为了演示和验证稳定器设计的就地相位补偿法在多机电力系统中的应用,介绍在多机电力系统中,就地补偿设计稳定器的2个应用实例。第1个实例是在多机电力系统中就地补偿设计电力系统稳定器（power system stabilizer,PSS）,阻尼电力系统局部模振荡。第2个实例是就地补偿设计附加在静态同步补偿器（static synchronous compensator,STATCOM）上的稳定器,抑制多机电力系统中的区域模振荡,并给出在一个16机电力系统中的应用计算和仿真结果。
基金supported by the National Key Research and Development Plan(2018YFB1201601-12)。
文摘Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.
文摘目的:系统分析各类医生薪酬支付方式对医疗服务提供行为及结果的影响。方法:采用范畴综述法,以Web of Science和中国知网、维普及万方为数据源,“医生”“薪酬”“支付方式”和“医生行为”等为主题词,检索到相关文献2255篇,通过制定严格的筛选程序最终纳入70篇相关研究。结果:按项目支付激励医生提供足量服务,但易导致过度医疗;固定薪水与按人头支付有助于控制成本,但易引发服务不足;DRG/DIP在医疗服务数量与质量方面的优势随患者病情加重而减弱。混合支付方式能够有效平衡医疗服务数量与成本,而按绩效支付在医疗质量提升方面总体表现突出。结论:医生薪酬单一支付方式难以实现医疗服务提供行为及结果最优化,且质量导向不足,多种支付方式与质量激励相融合的混合支付体系亟待构建。同时,建议深化医保结余薪酬转化机制改革,充分落实公立医院分配自主权,加快建立与医保支付和绩效考核协同的医生薪酬混合支付方式。
文摘随着新能源发电比例越来越高,其受电网三相不平衡的影响越来越明显,尤其负序超标是导致电力系统安全性降低的重要原因。统一潮流控制器(unified power flow controller,UPFC)具有调节各序电流输出的能力,可用于提升系统的平衡性。为此,首先建立基于解耦-补偿原理的UPFC正序最优补偿潮流算法;其次构建UPFC的负序补偿电流控制模型,将电压不平衡补偿的优化求解问题归结为凸二次约束二次规划(quadratically constrained quadratic programming,QCQP)问题,并采用原-对偶内点法求取UPFC的负序电流最优输出值;最后提出计及正序网损与负序电压指标的负序电压补偿最优潮流(optimal power flow,OPF)计算方法以及区域负序电压总体补偿策略。通过算例分析验证所提出方法的可行性与有效性。
文摘为了抑制轴向磁场磁通切换永磁(axial field flux-switching permanent magnet,AFFSPM)电动机齿槽转矩引起的转矩脉动,提出一种基于自适应扩展卡尔曼滤波器的齿槽转矩抑制方法.该方法根据齿槽转矩分析结果,以及AFFSPM电动机数学模型和损耗模型,将齿槽转矩引起的系统转矩脉动作为扩展状态变量,与电流环的反馈电流一起构造系统扩张状态空间方程.在状态估计过程中引入了遗忘因子,提高观测精度和速度.与基于谐波电流注入法抑制齿槽转矩的控制方法进行了控制性能和突变工况对比.结果表明:所提出控制方法在低速时转矩脉动降低了43.5%,电损耗降低了14.8%,能更有效抑制齿槽转矩脉动和提高系统效率.
文摘随着配电网中分布式光伏(distributed photovoltaic,DPV)大量并网,电压越限和电压波动越来越严重,考虑新型电能质量治理装置的电压无功优化协调控制方法需要进一步完善,以适应电网的新变化。该文考虑了新型柔性有载调压变压器(on-load tap changer,OLTC)的电能质量调节作用,提出一种两阶段电压无功优化协调控制方法,其中一阶段为日前小时级调度阶段,根据分布式光伏和负荷的预测数据,通过潮流计算和迭代优化,获取DPV的有功出力结果、柔性OLTC分接头和电容器组的投切结果;二阶段为分钟级无功优化阶段,在第一阶段的基础上,考虑柔性OLTC和DPV的无功出力特性,调节装备无功出力的同时修正第一阶段电容器组投切组合,进一步降低各个节点最大电压偏差,使配电网电压分布更合理。搭建了IEEE33节点配电系统仿真模型,所提出的考虑柔性OLTC的两阶段电压无功优化协调控制方法能够在常规经济性最优目标下的88.07%DPV消纳水平基础上提高9.29%,同时满足全节点全时段电压偏差小于0.1pu,综合经济性提高7.8%,结果证明了所提方法的合理性和有效性。
