Acoustic monitoring

The "SIMON" Project ("On-line acoustic monitoring of structural integrity of critical power plant components operating at high temperatures") had a duration of 4 years (1.10.1993 -30.09.1997) the Project Consortium included CISE (Project Coordinator, I), MITSUI BABCOCK ENERGY (UK), HERIOT-WATT UNIVERSITY (IK), PROET / EDP (P) and ENEL (I). 

BE-60S6 On-line acoustic monitoring of structural integrity of critical power plant comoonents oneratinn at hiah temoeratiire Mr. C G. De Michairs CISE SpA... 

M. Halstensen, S. de Silva, K.H. Esbensen, Acoustic monitoring of pneumatic transport lines - from noise to information, KONA Powder and Particle, 16, 170-178 (1998). 

In contrast to many other monitoring systems, the measuring chamber of a photo-acoustic monitor is sealed. Hence, the air must be analyzed as discrete samples rather than continuously. Nonetheless, this does not adversely affect the response time because small cell volumes, typically 3 cm3 can be used due to the high sensitivity available. Small discrete samples can be taken frequently and the true concentration of the ambient air measured. 

The experimental system is shown in Figure 4.9. The tested samples are placed in an airtight chamber whose volume is 301. By using a water bath, the chamber and air temperature can be maintained at the desired temperature. Tests were conducted at four air temperatures 18 0.5 °C, 30 0.8 °C, 40 0.8 °C and 50 0.6 °C, with air humidity uncontrolled but in the range 60 8%. After the system reaches thermal equilibrium, a dose of saturated formaldehyde vapor is injected into the chamber and thereafter the instantaneous concentrations of formaldehyde in the chamber are continuously recorded by an INNOVA-1312 until the equilibrium concentration C(y is reached at the equilibrium time, There are several reasons for applying a real-time photo-acoustic monitor to measure the instantaneous chamber compound concentrations for this research. First, its sampling volume is small and the air can be returned into the chamber... 

It has now been shown that sound is given out during the course of many chemical reactions, and that the acoustic energy released is possibly a measure of the extent of the reaction. If this link is proved, then acoustic monitoring of chemical reactions may well become widespread since the detector (the microphone) is attached to the outside of the vessel in which the reaction takes place and sound is generated by reactions which are difficult to monitor by conventional means, such as gel formation. 

The results presented here demonstrate that thin films can be characterized based on acoustical monitoring of changes in film mass density, conductivity, and viscoelasticity. Additional sensing mechanisms are available to probe film properties. Some examples are thin-film dielectric constant, stress, and structure (e.g., roughness). Some of these sensing mechanisms will be hard to quantify since they involve a complex interaction (e.g., wave attenuation based on wave scattering due to film roughness) however, they may still be useful to provide a qualitative monitor based on empirical data. 

Rudd, D. The use of acoustic monitoring for the control and scale-up of a tablet granulation process. J. Proc. Anal. Tech. 2004, 1 (2), 8-11. 

To some extent, progress has been limited by the availability of measurements on exchange processes. Until recently, temperature microstructure measurements were the primary approach to quantify near-surface turbulence. The instruments needed to do this were expensive and difficult to operate. The situation is now considerably improved. Microstructure sensors more suited to field use are commercially available, and are more user-friendly . Alternative methods to observe or infer mixing processes have also been perfected, including free-fall CTDs, acoustic doppler sensors and acoustically monitored floats. As these techniques are refined and deployment, operation, and analysis become more routine, it will become increasingly practical to incorporate a mixing component into field studies of UVR effects. 

Hagstrum, D.W., Vick, K.W., and Webb, J.C. 1990b. Acoustical monitoring of Rhyzopertha dominica (Coleoptera Bostrichidae) populations in stored wheat. J. Econ. Entomol. 83, 625-628. 

Tozser O, Elliott P (2000) Continuous Acoustic Monitoring of Prestressed Stmc-tures. In Proceedings, 2000 Annual Conference Canadian Society of Civil Engineers - 3 Stmctural Specialty Conference, London, Ontario. 

Principles and Characteristics The use of acoustic monitoring techniques for process analysis and control is becoming more relevant in industry. Ultrasonic signals have attributes that are well suited for characterisation of multiphase fluids and flows. The signals have the ability to interrogate fluids and dense opaque suspensions, penetrate vessel and process walls, and are not degraded by noisy process conditions because the signal frequencies differ from that of machinery. 

Acoustic monitoring Works In an operating pipeline Can detect wire breaks during monitoring period and locate them Works in all types of prestressed concrete pipes Oniy detects damage that occurs during monitoring period... 

The primary-side operator returned to his station and began monitoring the pressure in the pressurizer, which was near the PORV set point of 2425 psig. The PORV then opened and he watched the pressure decrease. The indicator in front of him signaled that there was a closed signal to the PORV and that it should be closed. The acoustic monitor installed after the TMI accident was available to him to verify that the PORV was closed, but he did not look at it. Instead, he looked at the indicated pressurizer level, which appeared steady, and based on simulator training, he concluded that the PORV was closed. In fact, the PORV had not completely closed and, as a result, the pressure... 

Brandes, T. S. (2005). Tropical ecology, assessment, and monitoring (team) initiative acoustic monitoring protocol. Version 2.1. Available at http //www.teamnetwork.org/files/ protocols/amphibian/TEAMAcoustic-PT-EN-2.1.pdf. 

Riede, K. (1998). Acoustic monitoring of Orthoptera and its potentitil for conservation. Journal of Insect Conservation, 2 217-223. 

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