本文在Stein恒等式(Stein’s identity)的框架下,给出了一种适用于有限样本场合的全新的修正Akaike信息准则(corrected Akaike information criterion),所提出的新准则适用于非常一般的协方差结构.在一定的正则性条件下,本文建立了所提...本文在Stein恒等式(Stein’s identity)的框架下,给出了一种适用于有限样本场合的全新的修正Akaike信息准则(corrected Akaike information criterion),所提出的新准则适用于非常一般的协方差结构.在一定的正则性条件下,本文建立了所提出准则的渐近有效性.应用带有自回归误差的空间回归模型进行模拟,结果表明,在备选模型与真实的数据生成过程之间的差异较小时,本文所提出方法的表现是令人满意的.当这种差异变大时,本文所提出的方法与其他已有方法相比也非常有竞争力.所提出的方法也被用于一组实际数据(社区犯罪数据)的分析中,所得到的结果更进一步支持了我们的方法在实际数据分析中的应用.展开更多
A powerful investigative tool in biology is to consider not a single mathematical model but a collection of models designed to explore different working hypotheses and select the best model in that collection.In these...A powerful investigative tool in biology is to consider not a single mathematical model but a collection of models designed to explore different working hypotheses and select the best model in that collection.In these lecture notes,the usual workflow of the use of mathematical models to investigate a biological problem is described and the use of a collection of model is motivated.Models depend on parameters that must be estimated using observations;and when a collection of models is considered,the best model has then to be identified based on available observations.Hence,model calibration and selection,which are intrinsically linked,are essential steps of the workflow.Here,some procedures for model calibration and a criterion,the Akaike Information Criterion,of model selection based on experimental data are described.Rough derivation,practical technique of computation and use of this criterion are detailed.展开更多
The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networ...The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.展开更多
The computational accuracy and efficiency of modeling the stress spectrum derived from bridge monitoring data significantly influence the fatigue life assessment of steel bridges.Therefore,determining the optimal stre...The computational accuracy and efficiency of modeling the stress spectrum derived from bridge monitoring data significantly influence the fatigue life assessment of steel bridges.Therefore,determining the optimal stress spectrum model is crucial for further fatigue reliability analysis.This study investigates the performance of the REBMIX algorithm in modeling both univariate(stress range)and multivariate(stress range and mean stress)distributions of the rain-flowmatrix for a steel arch bridge,usingAkaike’s Information Criterion(AIC)as a performance metric.Four types of finitemixture distributions—Normal,Lognormal,Weibull,and Gamma—are employed tomodel the stress range.Additionally,mixed distributions,including Normal-Normal,Lognormal-Normal,Weibull-Normal,and Gamma-Normal,are utilized to model the joint distribution of stress range and mean stress.The REBMIX algorithm estimates the number of components,component weights,and component parameters for each candidate finite mixture distribution.The results demonstrate that the REBMIX algorithm-based mixture parameter estimation approach effectively identifies the optimal distribution based on AIC values.Furthermore,the algorithm exhibits superior computational efficiency compared to traditional methods,making it highly suitable for practical applications.展开更多
研究了基于暂态地电压法(Transient Earth Voltage,TEV)的开关柜局部放电定位问题,针对传统定位方法存在的主要问题,提出了一种局部放电脉冲自动提取与匹配方法。利用Akaike信息准则法(Akaike Information Criterion,AIC)进行信号时间...研究了基于暂态地电压法(Transient Earth Voltage,TEV)的开关柜局部放电定位问题,针对传统定位方法存在的主要问题,提出了一种局部放电脉冲自动提取与匹配方法。利用Akaike信息准则法(Akaike Information Criterion,AIC)进行信号时间差的自动精确求解,根据多路信号时间差实现局部放电定位。基于该方法组建了包括四通道传感器、高速采集卡及上位机可视化处理软件等的便携式检测系统,实现了TEV波形的采集、显示、波形分析及信号时间差的自动确定方法,实现局部放电源的自动定位。最后利用试验证明了该方法较传统仪器所使用的阈值法确定时间差效果更加准确。展开更多
空间信号源数检测是阵列信号处理的关键问题之一,该文针对低信噪比下传统检测方法的性能差的问题,提出了一种基于近似特征向量的检测新方法DTAE(Detection Technique based on Approximate Eigenvectors)来改善低信噪比下传感器阵列的...空间信号源数检测是阵列信号处理的关键问题之一,该文针对低信噪比下传统检测方法的性能差的问题,提出了一种基于近似特征向量的检测新方法DTAE(Detection Technique based on Approximate Eigenvectors)来改善低信噪比下传感器阵列的信源数检测性能。该方法首先利用波束形成器在空间做预扫描来估计信号群中心的位置,以这些位置作为参考方向计算接收数据协方差矩阵的特征向量的近似值,然后使用特征向量的近似值对阵列输出数据加权,最后计算加权输出数据的频域峰值-平均功率比值从而估计信号源的个数。仿真结果表明,提出的新方法在低信噪比下的检测性能显著优于AIC(Akaike Information Criterion)等方法,有一定的工程应用价值。展开更多
文摘本文在Stein恒等式(Stein’s identity)的框架下,给出了一种适用于有限样本场合的全新的修正Akaike信息准则(corrected Akaike information criterion),所提出的新准则适用于非常一般的协方差结构.在一定的正则性条件下,本文建立了所提出准则的渐近有效性.应用带有自回归误差的空间回归模型进行模拟,结果表明,在备选模型与真实的数据生成过程之间的差异较小时,本文所提出方法的表现是令人满意的.当这种差异变大时,本文所提出的方法与其他已有方法相比也非常有竞争力.所提出的方法也被用于一组实际数据(社区犯罪数据)的分析中,所得到的结果更进一步支持了我们的方法在实际数据分析中的应用.
基金SP is supported by a Discovery Grant of the Natural Sciences and Engineering Research Council of Canada(RGOIN-2018-04967).
文摘A powerful investigative tool in biology is to consider not a single mathematical model but a collection of models designed to explore different working hypotheses and select the best model in that collection.In these lecture notes,the usual workflow of the use of mathematical models to investigate a biological problem is described and the use of a collection of model is motivated.Models depend on parameters that must be estimated using observations;and when a collection of models is considered,the best model has then to be identified based on available observations.Hence,model calibration and selection,which are intrinsically linked,are essential steps of the workflow.Here,some procedures for model calibration and a criterion,the Akaike Information Criterion,of model selection based on experimental data are described.Rough derivation,practical technique of computation and use of this criterion are detailed.
基金Project supported by the National Natural Science Foundation of China(Grant No.12072340)the Chinese Scholarship Council and the Australia Research Council through a linkage project fund。
文摘The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region.Despite intensive studies on the partitioning of urban road networks,the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question.This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm.Starting from selected random walkers,the road network is partitioned from the early morning when congestion emerges.A modified Akaike information criterion is defined to find the optimal number of partitions.Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions.The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.
基金jointly supported by the Fundamental Research Funds for the Central Universities(Grant No.xzy012023075)the Zhejiang Engineering Research Center of Intelligent Urban Infrastructure(Grant No.IUI2023-YB-12).
文摘The computational accuracy and efficiency of modeling the stress spectrum derived from bridge monitoring data significantly influence the fatigue life assessment of steel bridges.Therefore,determining the optimal stress spectrum model is crucial for further fatigue reliability analysis.This study investigates the performance of the REBMIX algorithm in modeling both univariate(stress range)and multivariate(stress range and mean stress)distributions of the rain-flowmatrix for a steel arch bridge,usingAkaike’s Information Criterion(AIC)as a performance metric.Four types of finitemixture distributions—Normal,Lognormal,Weibull,and Gamma—are employed tomodel the stress range.Additionally,mixed distributions,including Normal-Normal,Lognormal-Normal,Weibull-Normal,and Gamma-Normal,are utilized to model the joint distribution of stress range and mean stress.The REBMIX algorithm estimates the number of components,component weights,and component parameters for each candidate finite mixture distribution.The results demonstrate that the REBMIX algorithm-based mixture parameter estimation approach effectively identifies the optimal distribution based on AIC values.Furthermore,the algorithm exhibits superior computational efficiency compared to traditional methods,making it highly suitable for practical applications.
文摘研究了基于暂态地电压法(Transient Earth Voltage,TEV)的开关柜局部放电定位问题,针对传统定位方法存在的主要问题,提出了一种局部放电脉冲自动提取与匹配方法。利用Akaike信息准则法(Akaike Information Criterion,AIC)进行信号时间差的自动精确求解,根据多路信号时间差实现局部放电定位。基于该方法组建了包括四通道传感器、高速采集卡及上位机可视化处理软件等的便携式检测系统,实现了TEV波形的采集、显示、波形分析及信号时间差的自动确定方法,实现局部放电源的自动定位。最后利用试验证明了该方法较传统仪器所使用的阈值法确定时间差效果更加准确。
文摘空间信号源数检测是阵列信号处理的关键问题之一,该文针对低信噪比下传统检测方法的性能差的问题,提出了一种基于近似特征向量的检测新方法DTAE(Detection Technique based on Approximate Eigenvectors)来改善低信噪比下传感器阵列的信源数检测性能。该方法首先利用波束形成器在空间做预扫描来估计信号群中心的位置,以这些位置作为参考方向计算接收数据协方差矩阵的特征向量的近似值,然后使用特征向量的近似值对阵列输出数据加权,最后计算加权输出数据的频域峰值-平均功率比值从而估计信号源的个数。仿真结果表明,提出的新方法在低信噪比下的检测性能显著优于AIC(Akaike Information Criterion)等方法,有一定的工程应用价值。
