Automatic detection system of aircraft noise events during acoustic climate long-term monitoring near airport

The paper presents a method and software application of automatic identification of aircraft noise sources in the long-term environment acoustic monitoring systems. The said method relies on automatic “meaning” of sounds recorded by the one measuring microphone (part of a monitoring station) and refer to the advanced pattern recognition technique based on the human auditory perceptions by using mel frequency cepstral coefficients (MFCC) of signals. The algorithm was developed in MATLAB language and implemented in National Instrument LabVIEW Environment as Aircraft Noise Events Detector (ANED) application

Noise and vibration exposure of hybrid PEM power supply users during its operation

Proton exchange membrane (PEM) fuel cells characterized the highest available current density of electricity, but their construction uses elements, which generate noise, vibration and requires the dissipation of heat. Emitting these physical fields into the environment from this type of power sources is a disadvantage due to the low detection requirements of military installations as well as operator safety. The paper presents the study of noise and vibration exposure users of 20 Watt PEM fuel cell users

Electroacoustic methods of determining the parameters of speech sound generator

The spectrum character of speech wave is connected with the fundamental frequency (F0) of human vocal folds vibration. As it is considered, F0 of the source during voicing contains an abundance of information on the larynx pathology, individual trait, the emotional state and ethnographic origin of speaker. The present paper presents results of research that conducted simultaneous measurement of fundamental frequency of vocal fold vibration by the electroglottography (EGG) and with the acoustic methods. The analysis of the F0 function exactitude and the usefulness of these methods were executed too

Vibroacoustic measurements and analysis of blasting works

Blasting works cause short-term high-energy shock waves - acoustic, air (airblast) and paraseismic. The duration of the event can be up to 2-3 seconds, while the rise time to the peak value is directly related to the delay between the individual explosive material (EM) and the firing sequence and ranges from a few to several milliseconds. Their propagation in the environment can affect people, animals and construction structures located not only in the close but also further distance from their source. If EM is placed on the surface of the earth during the detonation, the shock wave spreads evenly in all directions in the half-space, and when the detonation follows in rock, the wave usually travels in one direction and is accompanied by a paraseismic wave. However, the sound heard when detonating is part of the wave spectrum in the band from 20 to 20000 Hz, while the airblast itself has a frequency of less than 20 Hz. Since at some distance from the detonated EM, the parameters of the airblast are close to the parameters of the acoustic wave, the method of spreading the acoustic wave depends to a great extent on atmospheric conditions, i.e. density, temperature and humidity of the air, and from wind speed and its direction. To get to know the essence of the phenomenon of the impact of blasting works, measurements are carried out considering the propagation conditions, i.e. meteorological conditions as well as vibration analysis in the ground itself and on the building substructure. This paper presents the results of research carried out by the Authors in terms of the correct assessment of the impact range (acoustic, airblast, paraseismic waves) during EM detonation placed on the surface

Examination of the vibroacoustic characteristics of 6 kW proton exchange membrane fuel cell

An analysis of existing air independent propulsion system solutions shows that fuel cells have the potential to achieve the greatest energy efficiency and silencing actions resulting from direct conversion of energy during a chemical reaction without moving parts. This paper describes research intended to identify noise generated by a fuel cell demonstrator and the first phase of work related to its silencing. During these investigations main noise sources were determined, while sound propagation and sound insulation of the fuel cell enclosure were performed in accordance with the civilian and military standardization guidelines

Real-time LabVIEW application for diagnostics and evaluation of machine vibration

The paper describes the algorithm and real-time software application named “VibroTest”, created in National Instruments LabVIEW Environment for determine the status of the machine based on the standard ISO 10816-1 Mechanical vibration. Evaluation of mechanical vibration by measurements on non-rotating parts – part 1: General guidelines [1]. The study includes the methods of the measurement, the concepts of the measurement system and the method of the calculation

Assessment of noise and vibration hazards generated by hybrid PEM-FC personal power supply

The paper presents a part of ongoing research into the use of a proton exchange membrane fuel cell (PEM-FC) to power military installations and personal power supply of soldier or rescuer. Construction of this type device use elements, which generate vibration, noise and heat. Emitting these types of pollution worsens the detection of military installations as well as operator’s safety. The presented research includes the assessment of noise and vibration hazards generated by 20 Watt PEM-FC personal power supply which was created by Polish Naval Academy in consortium with Central Laboratory of Batteries and Cells in Poznan and Impact Clean Power Technology S.A. in Warsaw. Measurements of noise and vibration levels were performed in an anechoic chamber at AGH University of Science and Technology during nominal operation of the device. The vibration parameters transferred to external cover as well sound power level and the insulation effectiveness of device cover were determined

POMIARY HAŁASU GENEROWANEGO PRZEZ ELEKTROWNIE WIATROWE I OCENA ICH WPŁYWU NA ŚRODOWISKO

In the last decades increasing popularity of renewable energy sources, including wind energy, has been observed. Growing interest in that topic convinced authors to present different types of impact of wind turbines on humans and nature, on the basis of literature, field observations and measurements. The results of sound level measurements showed that levels of acceptable environmental noise were not exceeded in the proximity to the residential area (400 m from the closest turbine). In addition, our study showed that the infrasonic levels were below perception and acceptable levels, so according to current knowledge they should not be harmful for humans.W ostatnich latach obserwowany jest ciągły wzrost popularności odnawialnych źródeł energii, w tym turbin wiatrowych. Zwiększające się zainteresowanie tematem skłoniło autorów do zaprezentowania w niniejszym artykule różnych rodzajów oddziaływań turbin na człowieka i przyrodę, bazując na przeglądzie literaturowym, obserwacjach terenowych i pomiarach. Przeprowadzone pomiary hałasu generowanego przez pracujące turbiny wiatrowe REPowerMM92 na farmie w Łękach Dukielskich (woj. Podkarpackie) wykazały, że poziomy dźwięku ustalone w rozporządzeniach nie zostały przekroczone w pobliżu zabudowań oddalonych o 400 m od najbliższej turbiny. Ponadto, pomiary nie wykazały, by infradźwięki generowane przez przedmiotową farmę mogły osiągnąć poziomy, które według dzisiejszej wiedzy są uważane za szkodliwe dla człowieka

An on-line diagnostics application for evaluation of machine vibration based on standard ISO 10816-1

Machines that generate vibroacoustic processes are tested at every stage of their life cycle. Since the greatest changes in the level of machines’ pulsation are occurring during the exploitation, vibration parameters are often used to evaluate their operation. Many years of research, whose results and conclusions are contained in the standards give a good methodological tool to assess the state of machines. The most commonly used standard is ISO 10816-1. Mechanical vibration. Evaluation of mechanical vibration by measurements on non-rotating parts – Part 1: General guidelines. On the other hand, the standard itself is not enough, the current monitoring parameters contained in the standard requires to hold or construction of easily configurable system for measuring, analyzing and archiving. This paper describes the work includes the methods of the measurement, the concepts of the measurement system and the method of the calculation, algorithm and software applications named VibroTest, created in National Instrument LabVIEW Environment. This authors system allows assessment of the machine under test, based on the signals generated by the tested machine