Acoustic noise

By testing the adhesive joints for the shift, the loading curve appears to be almost linear until the destruction point. The acoustic noise curves for the weak samples are describing an increased activity at tbe initial loading moment, and just before tbe destruction. The strong samples are acoustically little active up to the start of the macro-destruction. 

This requirement hides an important provision. It not only applies to inspection, measuring, and test equipment but to the measurements that are performed with that equipment. Anywhere you intend performing product verification or monitoring processes you need to ensure that the environmental conditions are suitable. By environmental conditions is meant the temperature, pressure, humidity, vibration, lighting, cleanliness, dust, acoustic noise, etc. of the area in which such measurements are carried out. To avoid having to specify the conditions each time, you need to establish the ambient conditions and write this into your procedures. If anything other than ambient conditions prevail, you may need to assess whether the measuring devices will perform adequately in these conditions. If you need to discriminate between types of equipment, the ones most suitable should be specified in the verification procedures. 

Unsteady combustion is a strong source of acoustic noise. The emission of sound by gaseous combustion is governed by the classical set of conservation equations Mass conservation ... 

D.L Abugov and O.I. Obrezkov. Acoustic noise in turbulent flames. Combust. Explosions Shock Waves, 14 606-612, 1978. 

Acoustic noise should be kept away by enclosing the microscope in a metal container and placing the entire instrument in a quiet room, preferably without... 

The cantilever is excited into resonance by electrically exciting the piezoelectric cantilever mount. The frequency of the excitation wave is scanned in a given frequency range, and the frequency of maximum cantilever amplitude is taken as the resonance frequency. The frequency spectrum of the cantilever response shows the fundamental frequency as well as the harmonics of cantilever vibration. The cantilevers, however, also resonate in response to ambient conditions such as room temperature or acoustic noise without requiring any external power. 

If a coaxial cable is used to connect the tunneling tip to the input of the amplifier, a major source of noise is the capacitance of the coaxial cable itself. The typical capacitance between the center conductor and the shielding is 100 pF per meter. In response to the acoustic noise in the room, the coaxial cable deforms. The capacitance changes. The current is... 

In early type stars, the bottom boundary penetrates into convective core (Osaki 1975). Accordingly, convective motion of eddies excites sound waves, as in the case of acoustic noise emmision from incompressible turbulence, shown by Lighthill (1978). Since the frequency of excited waves is higher than the Brunt-Vaisala frequency at the photosphere, the waves are not trapped, but running outward (cf. Unno et al 1979). 

Petersen and Boll, 1981] Petersen, T. L. and Boll, S. F. (1981). Acoustic noise suppression in the context of a perceptual model. In Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing, volume 1086-1088. 

In this procedure it is assumed that musical signals are made up as additive combinations of tones (sinusoids) which represent the fundamental and harmonics of all the musical notes which are playing. Since this is certainly not the case for most non-musical signals, we might expect the method to fail for, say, speech extracts or acoustical noises. Fortunately, it is for musical extracts that pitch variation defects are most critical. The pitch variation process is modelled as a smoothly varying waveform with no sharp discontinuities, which is reasonable for most wow generation mechanisms. 

Erwood and Xydeas, 1990] Erwood, A. and Xydeas, C. (1990). A multiframe spectral weighting system for the enhancement of speech signals corrupted by acoustic noise. In SIGNAL PROCESSING V Theories and Applications, pages 1107-1110. Elsevier. 

For Tu < 0.10 %, the transition location is insensitive to Tu. Such low levels of disturbances are typical of acoustic noise that controls... 

An important cautionary note to consider in order to effectively obtain atomically-resolved images at elevated pressures (aside from increased susceptibility to acoustic noise) is that relative adhesive interactions of the Au clusters between the STM tip and the TiO2(H0) substrate can result in... 

The technique of a cavitation noise measurement is the basis for the methods of determination of the cavitation threshold [31]. It is well known that the occurrence of cavitation phenomena in liquid—formation and collapse of a large quantity of bubbles of different sizes which have their own resonance frequencies—results in radiation of white acoustic noise. Separate frequency peaks corresponding to resonance frequencies and subharmonics of cavitation bubbles being added together with frequency tones from other cavitation bubbles produce a spectrogram of noises quantitatively different from that of the base tone of the carrier ultrasonic frequency which is used during the current US treatment. 

The AFP step height repeatability is < 5A on a lpm step height standard. Total indicated runout (TIR) is <10nm for a 10mm profile. The noise floor in closed loop mode is - 4.5A RMS in a cleanroom with 76dBc acoustic noise. In open loop mode, under the same conditions, the noise floor is - 1.5 A RMS. 

As explained below, it is suggested that accurate measurements of acoustic noise very near the jet plume may provide critical data which are required to validate computational jet-noise models. Further, it appears that only data acquired very near the plume can provide such information. Although there are several different specific sources of jet-engine noise [1], they are all linked to unsteady flows associated with the mean flow of the engine exhaust. 

Sakagami, K., S. Akio, I. M. Chou. T. Kamakura, and K. Ikegaya. 1982. Statistical characteristics of finite amplitude acoustic noise propagating in a tube. J. Acoustical Society Japan 3 43-45. 

Scott, J.F. 1982. The nonlinear propagation of acoustic noise. Proc. Royal Society London A. 383 55-70. 

Bj0rn0, L., and S. N. Gurbatov. 1985. Evolution of universal high-frequency asymp>-totic forms of the spectrum in the propagation of high-intensity acoustic noise. Sov. Physics Acoustics 31 179-81. 

Raptis, A.C., Sheen, S. H., Roach, P. D., and Mech, J. F., Acoustic Noise Background and Sound Transmission Tests in a Slurry Line at the HYGAS Pilot Plant, Argonne National Laboratory Report, 1979 ANL-FE-49622-TM04. 

Th efore, the sensitivity can be increased by intracavity operation of the photoacoustic cell. Such a tracegas analyzer with a resonant cell operated in the cavity of a tunable COj laser is described by Shtrikman and Slatkine The cell could be operated without any windows in the lowest-order longitudinal mode, allowing the determination of the ethylene concentration in the laboratory air as a function of time. Windowless operation leads to additional pickup of ambient acoustic noise. The authors estimate that with a closed cell and a 30 W laser, concentrations lowra-than 10" (3 10" cm ) could be measured... 

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