54,080 research outputs found
THE APPLICATION OF MULTIVARIATE DISTANCE MATRIX REGRESSION IN TRANSPORTATION FOR TRAFFIC ANALYSIS
A critical function of intelligent transportation systems is studying and analyzing the effects of road condition variables (e.g.
construction, severe weather, and the like) on traffic to aid in improving road designs, estimating travel time, and increasing safety. In this thesis, Multivariate Distance Matrix Regression (MDMR), a well-studied algorithm applied in brain research, is explored and applied in the transportation domain to assess the relationship and the effects of traffic conditions on transportation system performance. The Multivariate Distance Matrix Regression (MDMR) is utilized to study the relationship between input experimental factors and the association of response variables. When studying transportation, input factors can be represented as any factor that may have an effect on traffic, and response variables can be represented by traffic speed values over time for each segment of a road. The output is represented as a probability Value (P-Value) for each segment of the road as an indication of an effect of the studied factor on that specific segment. The National Performance Management Research Dataset (NPMRDS), (i.e., a probe-based traffic dataset) was used to study traffic performance based on specific factors by applying MDMR under different traffic scenarios.Moreover, a novel clustering algorithm for time series data is proposed by optimizing the F-statistic (i.e., a measurement metric to study the significance difference of two or more groups) to find the best segregation of time series between two or more groups. The clustering algorithm gave promising preliminary results when compared with K-means
On clustering procedures and nonparametric mixture estimation
This paper deals with nonparametric estimation of conditional den-sities in
mixture models in the case when additional covariates are available. The
proposed approach consists of performing a prelim-inary clustering algorithm on
the additional covariates to guess the mixture component of each observation.
Conditional densities of the mixture model are then estimated using kernel
density estimates ap-plied separately to each cluster. We investigate the
expected L 1 -error of the resulting estimates and derive optimal rates of
convergence over classical nonparametric density classes provided the
clustering method is accurate. Performances of clustering algorithms are
measured by the maximal misclassification error. We obtain upper bounds of this
quantity for a single linkage hierarchical clustering algorithm. Lastly,
applications of the proposed method to mixture models involving elec-tricity
distribution data and simulated data are presented
Classification of damage in structural systems using time series analysis and supervised and unsupervised pattern recognition techniques
Peer reviewedPostprin
Relation between Financial Market Structure and the Real Economy: Comparison between Clustering Methods
We quantify the amount of information filtered by different hierarchical
clustering methods on correlations between stock returns comparing it with the
underlying industrial activity structure. Specifically, we apply, for the first
time to financial data, a novel hierarchical clustering approach, the Directed
Bubble Hierarchical Tree and we compare it with other methods including the
Linkage and k-medoids. In particular, by taking the industrial sector
classification of stocks as a benchmark partition, we evaluate how the
different methods retrieve this classification. The results show that the
Directed Bubble Hierarchical Tree can outperform other methods, being able to
retrieve more information with fewer clusters. Moreover, we show that the
economic information is hidden at different levels of the hierarchical
structures depending on the clustering method. The dynamical analysis on a
rolling window also reveals that the different methods show different degrees
of sensitivity to events affecting financial markets, like crises. These
results can be of interest for all the applications of clustering methods to
portfolio optimization and risk hedging.Comment: 31 pages, 17 figure
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