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In this paper, we present a novel approach for the sensing of erosive cavitation phenomena in underwater facilities. Cavitation phenomena are known for their destructive capacity of underwater structures and are caused by the pressure decreasing followed by an implosion when the cavitation bubbles find an adverse pressure gradient. Conventional cavitation detection techniques are based on passive...
The underwater object imaging is an important task for the surveillance and monitoring of underwater environment in a non-intrusive manner. The acoustic methods have been proved to be very powerful for the detection and localization of underwater objects. This paper proposes a new method for object imaging based on an acoustic system that uses multiple elements. The image is obtained using two main...
In this paper, we present a new approach of time of flight (TOF) estimation using wide band signals, based on compressive sensing (CS) reconstruction in warped domain. In real conditions, constraints related to signal's transmitting/receiving (such as the transducers configuration or the experimental setup) can affect the informational content of the signal. Thus, the received signals need content...
Time-frequency analysis is naturally the way of characterization of non-stationary signals. One fundamental parameter of the any-non-stationary is the Instantaneous Frequency Law of its components. The Instantaneous Frequency Law (IFL) estimation is usually subject of tracking in time-frequency domain, especially in the case of complex time-frequency structures. Using the concept of phase diagram...
The paper presents a different approach based on an active acoustic system for the characterization of a vortex generating cavitation phenomenon. In the present work, the experiment was carried out in a reduced scale facility. The flow rate of the hydraulic system was varied and, when the flow became stable, the acoustic active system was started. The system is based on two ultrasonic transceivers...
This paper presents a new technique for acoustic transducers position offset compensation, based on compressive sensing reconstruction in the warped domain. In underwater acoustics, the transducers relative position is important for applications involving direction of arrival estimation, localization or source detection. When the transmitter-receiver transducers configuration is inappropriate, the...
Detection of objects in underwater environment is an important operation that can be aimed to assess the pollution in the region under study as well as to prevent intrusion of undesired objects in off shore power production facilities or in the restricted entrance area. The use of acoustic methods has been proven to be very powerful for the detection and localization of the underwater objects. This...
The distributed array of sensors is an interesting concept in the context of underwater environment monitoring. The signal processing distributed at sensors level has to have a low consumption (much less than the data transmission) and, in the same time, the processing efficiency needs to be satisfactory compared with a processing without any algorithmic complexity constraint. In this paper, we define...
Transient signals have proved to be difficult to characterize/classify because of their short duration and broad spectrum. Methods based on time-frequency analysis are used for transient detection, but their characterization is limited when it comes to similar signals that have close amplitudes and frequencies. This paper presents the multi-lag phase space analysis, an alternative to the classical...
From twenty years we promote the idea that engineering's systems (and not only!) are nonlinear ones and usually can have chaotically behaviors and their associated processes need special studies' methods. In this paper we present two directions from our research: cryptography based on chaos and a new method to analyze signals from nonlinear dynamical systems.
The paper presents an acoustic signal processing approach for the surveillance of a water pipe and the characterization of the water hammer effect. The experiment is based on ultrasonic transceivers and the validation is made with pressure sensors. The major objective is to quantify the pressure variation into the pipe using a non-intrusive method. Therefore, the speed of the transient was determined...
This paper presents several methods applied for the detection and localization of electrical arcs measured while survelling photovoltaic power systems. Firstly, we proposed the use of energy detectors for transients (spectrogram and wavelet) and compared them with statistical methods (Maximum Likelihood Estimation (MLE)), classical signal processing methods (Matched Filter, Zero Crossing), but not...
This paper presents two methods applied in the context of surveilling and localizing electrical arcs which usually occur in photovoltaic power systems. The wavelet analysis has proved to be very powerful in transient signal detection, namely in multiscale edge detection, thereby we use this method to detect the electrical arcs and to localize them in time. Secondly, we applied the recurrence plot...
This paper proposes a new method for detection of the vortex presence in fluid flow based on an active acoustic system. The experiment that validates the theory was done on a reduced scale facility using ultrasonic transceivers. The main objective was to highlight the effect of a cavitation vortex on an applied wide band signal. In order to accomplish that, the Recurrence Plot Analysis (RPA) was investigated...
In this paper, we introduce a general framework for waveform design and signal processing, dedicated to the study of turbulent flow phenomena. In a bi-static configuration, by transmitting a specific waveform with a predefined instantaneous frequency law (IFL), within the bounds of the Kolmogorov spectrum, the turbulent media will modify the IFL at the receiving side. We propose a new methodology...
The fetal heart rate (FHR) is a fundamental tool for clinical monitoring, when investigating the wellbeing of the fetus. The detection of the QRS complex of the fetal electrocardiogram using the abdominal signal enables the non-invasive evaluation of the FHR. There are many clinical causes for FHR variability, but a slight variance indicates a good evolution of the pregnancy. The current study evaluates...
This paper highlights the main results of our research in the field of recurrence plot analysis in the last five years. It briefly discusses results in the study of the method itself, as well as in some applications of it, i.e. characterization of speech signals, detection and localization of partial discharges in electric cables, representation of transient signals, estimation of signal parameters,...
In this paper, we present two techniques for the localization of electric arcs produced in photovoltaic power systems. High order statistic analysis (HOSA) and recurrence plot analysis (RPA) have already proven successful in detecting the partial discharges associated with the production of an electric arc in a high voltage power system. However, this solves only the first half of the problem, since...
The field of electrocardiography (ECG) has been in existence for over a century, but the analysis of fetal ECGs is still in its infancy. This is, partly due to a lack of availability of elegant standard databases, partly due to the relatively low signal to noise ratio of the fetal ECG compared to maternal ECG. In this paper we applied recurrence plot analysis method for noninvasively recorded abdominal...
In this paper we approach the challenges of partial discharges (PD) detection in high voltage cables using signal processing techniques based on time frequency methods combined with Recurrence Plot Analysis (RPA) and high order spectrum analysis (HOSA). Detection of PD poses many problems in terms of speed of calculation, selection criteria and multitude of causes which lead to the occurrence of PD...
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