Application of the wavelet analysis to research the traffic flow intensity

The relevance of the work is the specific properties of the wavelet analysis, which make it possible to identify not only the amplitude-scale (frequency) characteristics of the time series under consideration, but also the evolution of these characteristics during the observation time. As a result of the study, it is advisable to identify those indicators of the intensity of traffic flow that may turn out to be indicators of possible problematic situations (congestion, traffic accidents, etc.). It is advisable to use them in the future when regulating and controlling traffic on the basis of processing information about traffic flows that comes from stationary video recording complexes of traffic violations. The object of study is a road with intensive one-way traffic, equipped with a software and hardware complex that allows measuring the characteristics of the flow of motor transport. The subject of the study is the daily intensity of the flow of cars. The purpose of this study is to identify patterns in the indicators evolution obtained using wavelet analysis as a result of processing of the time series of the car traffic intensity on the road network. As a theoretical and methodological approach, the wavelet transforms using the MHat wavelet, and the Morlet wavelet is used. The approach used by the authors allowed us to establish the correspondence of some characteristics obtained during the wavelet analysis with the evolution of the traffic flow intensity function during the daily observation time, which is the scientific novelty of the study. The wavelet analysis of the data of the video surveillance software and hardware complexes obtained during the day allowed us to construct time dependences of amplitude-scale (frequency) indicators of the car traffic intensity on the road connecting the central and rear areas of the city of Perm. As a result of the study of time series, experimental three-dimensional distributions of wavelet images, scalograms, skeletons and scalegrams of the function of the daily intensity of the traffic flow were obtained. An explanation of the characteristic features of the obtained dependencies and their relationship with the initial function of the traffic flow intensity is proposed. The practical significance lies in obtaining amplitude-scale (frequency) characteristics as a result of wavelet analysis of the traffic intensity using MHat and Morlet wavelets, which is of practical interest from the point of view of predicting the movement of vehicles, controlling the operation of traffic lights, monitoring the operation of equipment, etc. The direction of further research is to obtain, process, analyze and generalize the results of performing amplitude-scale wavelet analysis for time series of traffic flow intensity on parts of the road network with different vehicle traffic intensity

GENERATION OF DECELERATION PULSES OF THE TROLLEY IN CHILD RESTRAINT SYSTEMS’ DYNAMIC TESTS BASED ON SIMULATIONS AND EXPERIMENTAL VALIDATIONS

As one of devices for passive safety, child restraint system remains a positive factor in securing the safety of child occupants in vehicles’ collisions. Generation of deceleration pulses is essential for dynamic tests conducted to assess the safety performance according to many regulations such as UN Regulation No. 44. It deserves research on how to generate the qualified pulses conveniently and with low cost. A new method of convenience using steel pipes or tubes is recommended after all the factors influencing the deceleration being ascertained. Varied combinations of parameters make it possible and easy to optimize the deceleration pulses

Signal reconstruction, modeling and simulation of a vehicle full-scale crash test based on Morlet wavelets

Creating a mathematical model of a vehicle crash is a task which involves considerations and analysis of different areas which need to be addressed because of the mathematical complexity of a crash event representation. Therefore, to simplify the analysis and enhance the modeling process, in this paper a novel wavelet-based approach is introduced to reproduce acceleration pulse of a vehicle involved in a crash event. The acceleration of a colliding vehicle is measured in its center of gravity-this crash pulse contains detailed information about vehicle behavior throughout a collision. Three types of signal analysis are elaborated here: time domain analysis (i.e. description of kinematics of a vehicle in time domain), the frequency analysis (identification of the parameters of the crash pulse in frequency domain), and the time-frequency analysis, which comprises those techniques that study a signal in both the time and frequency domains simultaneously, using Morlet wavelet properties. Determination of time of occurrence of particular frequency components included in the measured acceleration pulse and further analysis of the obtained scalegram are based on the reproduction of each crash pulse component, according to the frequencies identified in the acceleration signal. Finally, by using the superposition principle, those major signal components are combined, yielding the reproduced crash pulse. The comparative analysis between the current method's outcome, the responses of models established previously by using different approach and the behavior of a real car is performed and reliability of the actual methods and tools is evaluated. © 2012 Elsevier B.V.