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12 results on '"Pettersson, Mats I."'

4. Vehicle Classification Based on Multiple Fuzzy C-Means Clustering Using Dimensions and Speed Features.

Author

Javadi, Saleh, Rameez, Muhammad, Dahl, Mattias, and Pettersson, Mats I.

Subjects
TRAFFIC monitoring, PATTERN recognition systems, FUZZY clustering technique, FEATURE extraction, TRAFFIC regulations
Abstract

Vehicle classification has a significant use in traffic surveillance and management. There are many methods proposed to accomplish this task using variety of sensors. In this paper, a method based on fuzzy c-means (FCM) clustering is introduced that uses dimensions and speed features of each vehicle. This method exploits the distinction in dimensions features and traffic regulations for each class of vehicles by using multiple FCM clusterings and initializing the partition matrices of the respective classifiers. The experimental results demonstrate that the proposed approach is successful in clustering vehicles from different classes with similar appearances. In addition, it is fast and efficient for big data analysis. [ABSTRACT FROM AUTHOR]

Published
2018
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10. Evaluation of Ionospheric Scintillation in GNSS Radio Occultation Measurements and Simulations

Author

Ludwig‐Barbosa, Vinícius, Sievert, Thomas, Rasch, Joel, Carlström, Anders, Pettersson, Mats I., and T. Vu, Viet

Abstract

Like any other system relying on transionospheric propagation, Global Navigation Satellite System (GNSS) Radio Occultation (GNSS‐RO) is affected by ionospheric conditions during measurements. Regions of plasma irregularities in Fregion create abrupt gradients in the distribution of ionized particles. Radio signals propagated through such regions suffer from constructive and destructive contributions in phase and amplitude, known as scintillations. Different approaches have been proposed in order to model and reproduce the wave propagation through ionospheric irregularities. We present simulations considering single‐slope power law model of irregularities integrated with Multiple Phase Screen (MPS) propagation. In this work, the capability of the scintillation model to reproduce features in low‐latitude MetOp measurements in the early hours of DOY 76, 2015 is evaluated. Power spectral density (PSD) analysis, scintillation index, decorrelation time, and standard deviation of neutral bending angle are considered in the comparison between the simulations and RO measurements. The results demonstrate the capability of the simulator to replicate an equivalent error contribution to the neutral bending angle measurement in cases of moderate to strong scintillation. Single‐slope power law model replicates comparable levels of S4 index and bending angle STDV in RO measurements with moderate scintillationModel yields total integrated phase variance with equivalent effect in the signal amplitude during the occultations

Published
2020
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