[en] Several methods for analysis of acoustic emission signals are presented. They are mainly oriented to detection of changes in noisy signals and characterization of higher amplitude discrete pulses or bursts. The aim was to relate changes and events with failure, crack or wear in materials, being the final goal to obtain automatic means of detecting such changes and/or events. Performance evaluation was made using both simulated and laboratory test signals. The methods being presented are the following: 1. Application of the Hopfield Neural Network (NN) model for classifying faults in pipes and detecting wear of a bearing. 2. Application of the Kohonnen and Back Propagation Neural Network model for the same problem. 3. Application of Kalman filtering to determine time occurrence of bursts. 4. Application of a bank of Kalman filters (KF) for failure detection in pipes. 5. Study of amplitude distribution of signals for detecting changes in their shape. 6. Application of the entropy distance to measure differences between signals. (author). 10 refs, 11 figs

[en] Video and audio from hundreds of smartphones and dashboard cameras combined with seismic, acoustic, and satellite measurements provide the first precise documentation of a 10 000-ton asteroid explosion

[en] Infrasound detection of nuclear explosion is one of important detection methods of nuclear explosion. The software of the infrasound detection system programmed by Visual C⁺⁺ is introduced. Moreover, the structural principle and working process of the detection system are discussed briefly, and the structure of software is provided. Furthermore, the classes and their hierarchy are analyzed emphatically

[en] Vibration spectrums of the test loop according to flow conditions were analyzed in order to identify the sources of vibration at peak frequencies. While a flow condition of the sweep test was changed by varying pump rotational speed from 450 rpm to 1500 rpm by the step 150 rpm, mid span acceleration of the test section in width-direction and dynamic pressure perturbation in the test section were measured. Other sources of vibration due to the flow structure interactions, such as acoustic resonance, blade pulsing frequency and bellows wrinkles, were investigated. Pressure perturbation in the section and acoustic resonance due to branch pipe give major effects to the vibration of the test section in high frequency range of 1.5 kHz to 2.8 kHz

[en] In the planned high-energy extension of the IceCube Neutrino Observatory in the deep ice at the geographical South Pole the spacing of detector modules will be increased with respect to IceCube. Because of these larger distances the quality of the optical geometry calibration is expected to deteriorate. To counter this an independent acoustic geometry calibration system based on trilateration is introduced. Such an acoustic positioning system (APS) has already been developed for the Enceladus Explorer Project (EnEx), initiated by the DLR Space Administration. In order to integrate such APS-sensors into the IceCube detector the power consumption needs to be minimized. In addition, the frequency response of the front-end electronics is optimized for positioning as well as the acoustic detection of neutrinos. The new design of the acoustic sensor and results of test measurements with an IceCube detector module are presented.

[en] In this informative article we propose a journey into the world of sounds, from generation to perception, and the parameters that allow you to distinguish one sound from a noise. Let us examine the reasons for which the same sound is perceived differently if heard outside in a small room or a large living room, from which we obtain the optimal characteristics of the materials to use to build a theater and a concert hall. Finally, we explain why the sound waves propagate with different speeds and different intensity in the air, in liquid or solid materials, from which we can get a quantitative estimate of the noise coming from the next room

No abstract available

[en] The theme of this thesis is included in the Antares international project whose object is to build a neutrino telescope located in a deep water environment in the Mediterranean sea. In deep water sea, a neutrino can interact with a water molecule. The collision generates a luminous flash and an acoustic wave. The goal of this work is to study this acoustic sound wave and develop a system able to detect the corresponding wave front and to estimate the initial direction of the particle. We first focus on the acoustic sound wave. Two different models are studied, and works made recently have led to a mathematical expression of both signal and wave front. Then, several detection methods are studied, from the most classical to the more recent ones. The experimental comparison in semi-real situation leads to the choice of a detection method: the Extended stochastic matched filter. Position and direction of the neutrino are now estimated with a Gauss-Newton inspired algorithm. This estimator is based on a wave front propagation model and on the time detection information given by the telescope hydro-phones. Performances of the system are then estimated. An antenna structure is then proposed and a global simulation finalizes this thesis. In this simulation, detection and estimation are based on the results found in the previous sections. Underwater sea noise is real and the results of the simulation valid our works. (author)

[en] The present invention is suitable to be used in a nuclear reactor, and an abrupt leak of high temperature and high pressure fluid is detected without increasing the number of microphones. Namely, a detection region using the microphone is shifted from a high frequency region with less circumferential noises to a region of ultrasonic waves. Further, impact vibrations of atmosphere (air) along with abrupt leak is determined as auxiliary signals. Leak generation signals are generated when the detection signals by the microphones and the auxiliary signals are generated at the same time. With a device having such a constitution, an abrupt leak can be detected at a great sound pressure in a frequency region with less circumferential noises always generated and at a slight lasting time. In addition, since a great sound in an audible region from a specific equipment can be avoided, influences of environmental noises are small. As a result, the number of microphones can be reduced. Further, in a case where the sound pressure is at a medium level accompanying abrupt air impact, it can be judged to be an abrupt leak. (I.S.)

[en] The present situation and advance in infra-sound monitoring technology of nuclear explosion in home and abroad as well as its application to international monitoring system of the Comprehensive Test Ban Treaty are introduced