针对高比例新能源电力系统,基于模型参数的电压支撑强度量化方法已具有较为深入的方法和结论,但是尚缺乏基于本地响应信息的电压支撑强度实时量化方法,电压支撑强度就地监测水平亟待提高。该文提出电压支撑强度实时量化方法,实现短路比...针对高比例新能源电力系统,基于模型参数的电压支撑强度量化方法已具有较为深入的方法和结论,但是尚缺乏基于本地响应信息的电压支撑强度实时量化方法,电压支撑强度就地监测水平亟待提高。该文提出电压支撑强度实时量化方法,实现短路比实时计算,及时给出安全预警信号,为提高新能源系统安全运行水平提供技术支撑。首先,构建实时短路比(real-time short circuit ratio,RSCR)及临界实时短路比(critical real-time short circuit ratio,CRSCR)指标,实现基于本地响应信息的短路比指标实时计算,提供电压支撑强度实时量测的指标基础;其次,提出有功功率裕度、稳态低电压两类安全约束下的RSCR裕度分析方法,通过建立RSCR与功率、电压之间的函数关系分析不同安全约束下RSCR裕度的适应性,为设置安全预警阈值提供参考;然后,构建实时量测系统架构,提出涵盖系统戴维南等值参数实时辨识、短路比指标实时计算、实时安全预警等功能的算法流程,建立电压支撑强度全流程实时量测方法;最后,通过算例验证RSCR、CRSCR的准确性以及实时量测方法的有效性。实现基于实时量测信息的电压支撑强度就地监测,可以为运维人员及时掌握新能源运行状态提供一定指导,支撑更高比例新能源并网消纳。展开更多
The gut microbiota is a complex ecosystem composed of many bacteria and their metabolites.It plays an irreplaceable role in human digestion,nutrient absorption,energy supply,fat metabolism,immune regulation,and many o...The gut microbiota is a complex ecosystem composed of many bacteria and their metabolites.It plays an irreplaceable role in human digestion,nutrient absorption,energy supply,fat metabolism,immune regulation,and many other aspects.Exploring the structure and function of the gut microbiota,as well as their key genes and metabolites,will enable the early diagnosis and auxiliary diagnosis of diseases,new treatment methods,better effects of drug treatments,and better guidance in the use of antibiotics.The identification of gut microbiota plays an important role in clinical diagnosis and treatment,as well as in drug research and development.Therefore,it is necessary to conduct a comprehensive review of this rapidly evolving topic.Traditional identification methods cannot comprehensively capture the diversity of gut microbiota.Currently,with the rapid development of molecular biology,the classification and identification methods for gut microbiota have evolved from the initial phenotypic and chemical identification to identification at the molecular level.This review integrates the main methods of gut microbiota identification and evaluates their application.We pay special attention to the research progress on molecular biological methods and focus on the application of high-throughput sequencing technology in the identification of gut microbiota.This revolutionary method for intestinal flora identification heralds a new chapter in our understanding of the microbial world.展开更多
针对中压配电网缺少实时量测、伪量测精度较低以及现有的动态状态估计(dynamic state estimation,DSE)方法均采用恒定系统处理状态过程噪声的问题,提出了一种基于改进自适应无迹卡尔曼滤波(unscented kalman filter,UKF)算法的中压配电...针对中压配电网缺少实时量测、伪量测精度较低以及现有的动态状态估计(dynamic state estimation,DSE)方法均采用恒定系统处理状态过程噪声的问题,提出了一种基于改进自适应无迹卡尔曼滤波(unscented kalman filter,UKF)算法的中压配电网鲁棒DSE方法。首先,利用中压配电网变压器低压侧的智能电表量测和变压器模型,推导出等效中压量测以增强中压配网量测冗余度;然后,借鉴信号处理技术对系统状态过程噪声的协方差矩阵实时更新并融入UKF算法,以减轻状态预测和量测滤波的不确定性;最后,基于15节点中压配电网进行仿真。仿真结果表明:所提方法能够有效地进行中压配电网的动态状态估计,获取更为精确的态势感知信息。展开更多
In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indi...In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indicate that the evolutions of wave velocities became progressively anisotropic under uniaxial loading due to the direction-dependent development of micro-damage.A wave velocity model considering the inner anisotropic crack evolution is proposed to accurately describe the variations of wave velocities during uniaxial compression testing.Based on which,the effective elastic parameters are inferred by a transverse isotropic constitutive model,and the evolutions of the crack density are inversed using a self-consistent damage model.It is found that the propagation of axial cracks dominates the failure process of brittle rock under uniaxial loading and oblique shear cracks develop with the appearance of macrocrack.展开更多
Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degrad...Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.展开更多
文摘针对高比例新能源电力系统,基于模型参数的电压支撑强度量化方法已具有较为深入的方法和结论,但是尚缺乏基于本地响应信息的电压支撑强度实时量化方法,电压支撑强度就地监测水平亟待提高。该文提出电压支撑强度实时量化方法,实现短路比实时计算,及时给出安全预警信号,为提高新能源系统安全运行水平提供技术支撑。首先,构建实时短路比(real-time short circuit ratio,RSCR)及临界实时短路比(critical real-time short circuit ratio,CRSCR)指标,实现基于本地响应信息的短路比指标实时计算,提供电压支撑强度实时量测的指标基础;其次,提出有功功率裕度、稳态低电压两类安全约束下的RSCR裕度分析方法,通过建立RSCR与功率、电压之间的函数关系分析不同安全约束下RSCR裕度的适应性,为设置安全预警阈值提供参考;然后,构建实时量测系统架构,提出涵盖系统戴维南等值参数实时辨识、短路比指标实时计算、实时安全预警等功能的算法流程,建立电压支撑强度全流程实时量测方法;最后,通过算例验证RSCR、CRSCR的准确性以及实时量测方法的有效性。实现基于实时量测信息的电压支撑强度就地监测,可以为运维人员及时掌握新能源运行状态提供一定指导,支撑更高比例新能源并网消纳。
文摘The gut microbiota is a complex ecosystem composed of many bacteria and their metabolites.It plays an irreplaceable role in human digestion,nutrient absorption,energy supply,fat metabolism,immune regulation,and many other aspects.Exploring the structure and function of the gut microbiota,as well as their key genes and metabolites,will enable the early diagnosis and auxiliary diagnosis of diseases,new treatment methods,better effects of drug treatments,and better guidance in the use of antibiotics.The identification of gut microbiota plays an important role in clinical diagnosis and treatment,as well as in drug research and development.Therefore,it is necessary to conduct a comprehensive review of this rapidly evolving topic.Traditional identification methods cannot comprehensively capture the diversity of gut microbiota.Currently,with the rapid development of molecular biology,the classification and identification methods for gut microbiota have evolved from the initial phenotypic and chemical identification to identification at the molecular level.This review integrates the main methods of gut microbiota identification and evaluates their application.We pay special attention to the research progress on molecular biological methods and focus on the application of high-throughput sequencing technology in the identification of gut microbiota.This revolutionary method for intestinal flora identification heralds a new chapter in our understanding of the microbial world.
文摘针对中压配电网缺少实时量测、伪量测精度较低以及现有的动态状态估计(dynamic state estimation,DSE)方法均采用恒定系统处理状态过程噪声的问题,提出了一种基于改进自适应无迹卡尔曼滤波(unscented kalman filter,UKF)算法的中压配电网鲁棒DSE方法。首先,利用中压配电网变压器低压侧的智能电表量测和变压器模型,推导出等效中压量测以增强中压配网量测冗余度;然后,借鉴信号处理技术对系统状态过程噪声的协方差矩阵实时更新并融入UKF算法,以减轻状态预测和量测滤波的不确定性;最后,基于15节点中压配电网进行仿真。仿真结果表明:所提方法能够有效地进行中压配电网的动态状态估计,获取更为精确的态势感知信息。
基金Projects(41502283,41772309)supported by the National Natural Science Foundation of ChinaProject(2017YFC1501302)supported by the National Key Research and Development Program of ChinaProject(2017ACA102)supported by the Major Program of Technological Innovation of Hubei Province,China。
文摘In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indicate that the evolutions of wave velocities became progressively anisotropic under uniaxial loading due to the direction-dependent development of micro-damage.A wave velocity model considering the inner anisotropic crack evolution is proposed to accurately describe the variations of wave velocities during uniaxial compression testing.Based on which,the effective elastic parameters are inferred by a transverse isotropic constitutive model,and the evolutions of the crack density are inversed using a self-consistent damage model.It is found that the propagation of axial cracks dominates the failure process of brittle rock under uniaxial loading and oblique shear cracks develop with the appearance of macrocrack.
基金Projects(51475462,61374138,61370031)supported by the National Natural Science Foundation of China
文摘Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.
