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Acoustic Measurements (acoustic + measurement)
Selected AbstractsAcoustic measurement of intake and grazing behaviour of cattleGRASS & FORAGE SCIENCE, Issue 2 2000Acoustic analysis of grazing behaviour was found to allow accurate identification of chewing and biting, and estimation of intake by cattle. Four steers grazed six types of turves, three were short (14, 16 and 20 cm tall), leafy turves from mowed Setaria lutescens with high application of N fertilizer, and three were tall (36, 49 and 62 cm tall), mature turves from uncut areas with low application of N fertilizer. Each animal grazed ten bites from each turf type while behaviour was videotaped and grazing sounds were recorded with a wireless microphone taped to the animal's forehead. The intake was measured by the difference in pre- and post-grazing turf weight, corrected for water loss. Chews and bites differed in acoustic characteristics, with bites producing more output in the 3,8 kHz frequency band. Discriminant analysis of the acoustic characteristics correctly classified chews and bites with 94% accuracy. Intake was predicted with a high degree of accuracy by total energy flux density (fJ m,2) in chewing sounds (EFDC), EFDC per chew and average intensity of chewing sound in the 1,2 and 2,3 kHz bands (R2=0·90, CV=3·6%). Although bite mass ranged from 1·37 to 4·50 g, EFDC per g of intake (CV=0·015) was not affected by treatments or animals. Chewing sounds carried more information about intake than biting sounds and chews per bite. Analysis of grazing sounds has the potential to overcome many of the problems associated with the measurement of grazing intake. [source] Flow regime determination in horizontal hydrotransport using non-intrusive acoustic probesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Katherine Albion Abstract A variety of flow regimes may be observed in the hydrotransport of solids. Maintaining a consistent operation requires rapid detection of any change in flow regime. The objective of this study was to develop reliable, non-intrusive, and on-line methods for flow regime detection in a hydrotransport pipe based on acoustic measurements. Slurries were transported in a 0.05 m diameter stainless steel hydrotransport pipe. Acoustic measurements were recorded by microphones along the length of the horizontal pipe. Two flow regimes were observed: suspended solids flow and flow over settled solids. Cycle and frequency analyses of the acoustic signals provided reliable identification of these flow regimes. Plusieurs régimes d'écoulement peuvent être observés dans le transport hydraulique des solides. Le maintien d'un fonctionnement consistant nécessite la détection rapide de tout changement dans le régime d'écoulement. L'objectif de cette étude est de développer des méthodes fiables, non intrusives et en continu pour la détection des régimes d'écoulement dans une conduite de transport hydraulique reposant sur des mesures acoustiques. Les suspensions ont été transportées dans une conduite de transport hydraulique en acier inoxydable de 0,05 m de diamètre. Les mesures acoustiques ont été enregistrées par des microphones le long de la conduite horizontale. Deux régimes d'écoulement ont été observés : l'écoulement de solides suspendus et l'écoulement au-dessus des solides déposés. Les analyses de cycle et de fréquence des signaux acoustiques fournissent une identification fiable de ces régimes d'écoulement. [source] Investigating the transport dynamics and the properties of bedload material with a hydro-acoustic measuring systemEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2008Andreas Krein Abstract This article deals with the following two questions. Are acoustic measurements in running waters appropriate for a highly resolved investigation of the bedload transport? Which characterizations of the bedload regarding mass and shape are possible via the acoustic signals? The signals were recorded by means of data recorders (Tascam Inc. DAP1 Portable Data Recorder) and hydrophones (International Transducer Corp. ITC-4001 A). The ITC-4001 is a shallow water omnidirectional transducer containing a flexural disc transducer utilizing Channelite-5400 ceramics mounted in a rugged corrosion-resistant housing. These hydrophones were screwed onto the bottom side of stainless steel plates, serving as a contact surface for the bedload in motion above them. After more than 100 series of tests in the laboratory, which indicated the basic relations between the dimension, shape and weight of the bedload and the resulting signal, field tests of the measuring system were conducted. By artificially produced flood waves in the small brooks Riverisbach, Olewiger Bach and by a winter flood wave in the River Moselle, it is possible to elaborate similar structures of the signal course of the bedload movement. The highest transport rates can be observed at the beginning of the increasing limbs and behind the peaks of the waves. At the beginning of the waves, the increasing transport power of the water and the loose material can be considered as the cause for this result. The high stream velocity behind the wave peaks explains the increase in the bedload transport so that material from the channel beds is unfastened and will be mobilized. The characterization of the bedload regarding the shape and mass is still limited regarding the field measurements and could be solved only for homogeneous grain sizes and single stones under laboratory conditions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Improved understanding of velocity,saturation relationships using 4D computer-tomography acoustic measurementsGEOPHYSICAL PROSPECTING, Issue 2 2005K. Monsen ABSTRACT A recently developed laboratory method allows for simultaneous imaging of fluid distribution and measurements of acoustic-wave velocities during flooding experiments. Using a specially developed acoustic sample holder that combines high pressure capacity with good transparency for X-rays, it becomes possible to investigate relationships between velocity and fluid saturation at reservoir stress levels. High-resolution 3D images can be constructed from thin slices of cross-sectional computer-tomography scans (CT scans) covering the entire rock-core volume, and from imaging the distribution of fluid at different saturation levels. The X-ray imaging clearly adds a new dimension to rock-physics measurements; it can be used in the explanation of variations in measured velocities from core-scale heterogeneities. Computer tomography gives a detailed visualization of density regimes in reservoir rocks within a core. This allows an examination of the interior of core samples, revealing inhomogeneities, porosity and fluid distribution. This mapping will not only lead to an explanation of acoustic-velocity measurements; it may also contribute to an increased understanding of the fluid-flow process and gas/liquid mixing mechanisms in rock. Immiscible and miscible flow in core plugs can be mapped simultaneously with acoustic measurements. The effects of core heterogeneity and experimentally introduced effects can be separated, to clarify the validity of measured velocity relationships. [source] Paired comparisons for the evaluation of crispness of cereal flakes by untrained assessors: correlation with descriptive analysis and acoustic measurementsJOURNAL OF CHEMOMETRICS, Issue 3 2005Philippe Courcoux Abstract This study investigates the effectiveness of the paired comparison method in the evaluation of a complex sensory attribute by untrained assessors. The crispness perception of cereal flakes by a panel of 100 consumers is measured using a complete block design, and the fitting of the Bradley,Terry,Luce model leads to a ranking of the samples on a crispness intensity scale. A log,linear formulation of the Bradley model provides insight into goodness-of-fit tests and allows the effects of covariates to be incorporated in the prediction of the sensory scores. Results show a high correlation between crispness assessment by consumers and rating of texture attributes by trained assessors. Acoustic emission is shown to have a significant effect on crispness perception, and the power spectra of signals recorded during compression provide a prediction of the crispness of cereal flakes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spectra of wavelet scale coefficients from process acoustic measurements as input for PLS modelling of pulp quality,JOURNAL OF CHEMOMETRICS, Issue 8-10 2002Anders Björk Abstract Acoustic and vibration signals are captured by simple standard accelerometers. These can often be mounted directly on operative process equipment, creating a completely non-invasive measurement system. The signals from the accelerometer are then amplified, digitized by an analogue-to-digital converter and stored in some suitable format in a PC. The method most often used for signal processing of acoustic data has been to apply variants of fast Fourier transform (FFT) on sampled data to produce a frequency domain representation. An alternative way tried here is to use the fast wavelet transform (FWT) in combination with FFT. The FWT has the advantage that it produces time-resolved representations and, on each time scale, different features can be extracted. However, in this case, time resolution has no meaning, since the starting points for data acquisitions were not fixed. The wavelet step can be seen as a series of pre-filters and it is here followed by FFT on coefficients at each wavelet scale. The results are compared to those obtained after FFT on the complete time series. We have used spectra of wavelet scale coefficients in an attempt to model pulp quality with PLS. In this case the number of points in the resulting wavelet multiresolution spectrum (WT-MRS) can be limited to a low number, e.g. 255 compared to 1025 with direct FFT on the time series. In the PLS modelling step the advantage is that the first two components describe Y much better than when using the conventional approach, e.g. 72% explained Y variance compared to 40%. A second advantage is that the model requires fewer coefficients. Copyright © 2002 John Wiley & Sons, Ltd. [source] Reconstructing small perturbations of scatterers from electric or acoustic far-field measurementsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 11 2008Mikyoung Lim Abstract In this paper, we consider the problem of determining the boundary perturbations of an object from far-field electric or acoustic measurements. Assuming that the unknown scatterer boundary is a small perturbation of a circle, we develop a linearized relationship between the far-field data and the shape of the object. This relationship is used to find the Fourier coefficients of the perturbation of the shape. Copyright © 2008 John Wiley & Sons, Ltd. [source] Flow regime determination in horizontal hydrotransport using non-intrusive acoustic probesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008Katherine Albion Abstract A variety of flow regimes may be observed in the hydrotransport of solids. Maintaining a consistent operation requires rapid detection of any change in flow regime. The objective of this study was to develop reliable, non-intrusive, and on-line methods for flow regime detection in a hydrotransport pipe based on acoustic measurements. Slurries were transported in a 0.05 m diameter stainless steel hydrotransport pipe. Acoustic measurements were recorded by microphones along the length of the horizontal pipe. Two flow regimes were observed: suspended solids flow and flow over settled solids. Cycle and frequency analyses of the acoustic signals provided reliable identification of these flow regimes. Plusieurs régimes d'écoulement peuvent être observés dans le transport hydraulique des solides. Le maintien d'un fonctionnement consistant nécessite la détection rapide de tout changement dans le régime d'écoulement. L'objectif de cette étude est de développer des méthodes fiables, non intrusives et en continu pour la détection des régimes d'écoulement dans une conduite de transport hydraulique reposant sur des mesures acoustiques. Les suspensions ont été transportées dans une conduite de transport hydraulique en acier inoxydable de 0,05 m de diamètre. Les mesures acoustiques ont été enregistrées par des microphones le long de la conduite horizontale. Deux régimes d'écoulement ont été observés : l'écoulement de solides suspendus et l'écoulement au-dessus des solides déposés. Les analyses de cycle et de fréquence des signaux acoustiques fournissent une identification fiable de ces régimes d'écoulement. [source] | |||||||||||||