Acoustic pressure

This article presents an approach to build and verify a tool for calculating aerodynamic noise characteristics of helicopter rotors. The calculation tool is built on the basis of combining the vortex lattice method and the Formulation 1A of Farrasat, which is one of solutions of the Ffowcs Williams-Hawkings (FW-H) equation.

12p viengels 25-08-2023 3 2   Download

This paper focused on evaluating those properties based on the data of acoustic emission and electrical contact voltage signal. Frictional experiments based on scratch test and pin-on-flat model were conducted with CrN coating, lubricant samples to obtain some experimental data, including contact pressure, friction force, friction coefficient, acoustic emission, and contact voltage.

12p vidudley 20-02-2023 6 2   Download

The interaction of a laser-excited circular acoustic wave in water on an epoxy-resin surface was studied directly and visually by photoelasticity imaging technique. The result shows the direct image of the pressure wave, shear wave, and Scholte waves, which are the three typical acoustic waves excited when an acoustic wave crosses a solid-liquid interface. This technique provides a clear, whole field image of the phenomena; and is a promising method to study the acoustic phenomena at the interfaces.

4p nguaconbaynhay12 01-06-2021 11 1   Download

Surface acoustic wave (SAW) sensors offer a sensitive platform for monitoring important physical entities with several advantages. They can operate well in extreme conditions such as high temperature, high pressure and toxic environment.

7p tamynhan4 06-09-2020 11 1   Download

In this paper the acoustic pressure analysis in a thick-walled hollow cylinder similar to a solid propellant rocket motor with non-uniform port geometry is carried out for meeting the requirements of various types of canister designs for industrial applications.

4p praishy2 27-02-2019 26 0   Download

Acoustic emission (AE) is a phenomenon in which elastic or stress waves are emitted from rapid, localized change of strain energy in material. The practical application of the AE first emerged in the 1950's, but only in the last 20 years the science, technology and applications of AE have progressed significantly.

230p lyly_5 22-03-2013 63 8   Download

Sputum examination is a key diagnostic procedure for patients suspected of having pulmonary TB, including those for whom bronchoscopy is planned.1,2 In addition, early identification of persons with TB remains the most effective way of preventing TB transmission. However, some patients are unable to produce sputum for examination. In such cases, sputum induction by aerosol inhalation and/or gastric aspiration has been preferred.

4p taisaocothedung 12-01-2013 50 1   Download

Brillouin scattering was discovered in 1922 by Louis Brillouin [1]. It is one of a number of characteristic scattering phenomena that occur when light interacts with solid, liquid or gaseous media and corresponds to the scattering of light from thermally-induced acoustical waves (propagating pressure/density waves) present in media at all temperatures. At normal light levels the amount of scattering is small. The characteristics of the scattering can offer interesting information about the properties of the medium (temperature, pressure) and form the basis for remote fibre sensor devices.

208p bachduong1311 07-12-2012 110 3   Download

The science of acoustics deals with the creation of sound, sound transmission through solids, and the effects of sound on both inert and living materials. As a mechanical effect, sound is essentially the passage of pressure fluctuations through matter as the result of vibrational forces acting on that medium. Sound possesses the attributes of wave phenomena, as do light and radio signals. But unlike its electromagnetic counterparts, sound cannot travel through a vacuum.

663p waduroi 03-11-2012 63 8   Download

Acoustic fatigue is due to a very high intensity excitation as a result of pressure waves caused by either engine or aerodynamic effects. Acoustically-induced cracking has occurred on the external surface of the lower nacelle and aft fuselage skins on the F/A-18, as illustrated in Figure 19.1. In the former region, overall sound pressure levels greater than 170dB have been measured in flight [l]. These high sound pressure levels appear to be a result of an aerodynamic disturbance at the inlet lip....

570p nhatkyvodanh 11-08-2012 78 8   Download

Acoustics is a discipline that deals with many types of fields wave phenomena. Originally the field of Acoustics was consecrated to the sound, that is, the study of small pressure waves in air detected by the human ear. The scope of this field of physics has been extended to higher and lower frequencies and to higher intensity levels. Moreover, structural vibrations are also included in acoustics as a wave phenomena produced by elastic waves. This book is focused on acoustic waves in fluid media and elastic perturbations in heterogeneous media....

0p ktcn_1 10-07-2012 80 8   Download

The final article in this section presents a modification to the Green’s function approach for modeling acoustic pressure, where the use of conformal mapping is replaced by a group of bound vortices. The author shows that the approach is readily extended to three dimensions. The method is discussed in the context of aircraft noise.

318p contentnew 12-04-2012 112 33   Download

Wet sulfate deposits: eastern North America. (Source: Environment Canada SOE 96-2, Spring 1996.) LK P, P0 S r, Dr t = reactivity index = pressure, Pa = surface area of the test panel, m2 = distance, m = time, s Pa, Pb = pressure, Pa W, W0 = power, pW Acoustic Enclosures, Turbine A-13 FIG. A-7 Trends in lake sulfate levels (North America). (Source: Environment Canada SOE 96-2, Spring 1996.

20p hiruscar 13-10-2010 74 6   Download

CHAPTER 24 NOISE MEASUREMENT AND CONTROL George M. Diehl, RE. Consulting Engineer Machinery Acoustics Phillipsburg, New Jersey 24.1 24.2 24.3 24.4 24.5 24.6 24.7 SOUND CHARACTERISTICS FREQUENCY AND WAVELENGTH VELOCITYOFSOUND SOUND POWER AND SOUND PRESSURE DECIBELS AND LEVELS COMBINING DECIBELS 711 712 24.14 MACHINES IN SEMIREVERBERANT LOCATIONS TWO-SURFACE METHOD MACHINERYNOISE CONTROL SOUNDABSORPTION NOISE REDUCTION DUE TO INCREASED ABSORPTION IN ROOM SOUNDISOLATION SINGLEPANEL COMPOSITE PANEL ACOUSTICENCLOSURES 716 717 719 719 24.15 712 24.16 712 24.17 712 24.18 712 24.19 24.20 24.

18p hadalabo 29-09-2010 48 5   Download