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Counting and sizing large farmed fish such as tuna is often performed during their transfer from one net cage to another. Dual-frequency-identification sonar (DIDSON) provides an automated fish counting and sizing tool. However, its counter and sizer are not suitable for measuring farmed fish because of net movements due to currents and subsequent frequent image breakups. This paper presents a fully automated acoustic method to count and size farmed fish during fish transfer by using DIDSON imaging. The background is subtracted from the image after being stabilized by an image phase-only correlation method. The segmentation of the fish is obtained by tracing the edges with a contour tracing method. To prevent recounting the same fish, a Kalman filter algorithm was designed and adapted to predict fish movements. Automated counting was performed by analyzing the spatiotemporal trajectory of the track. The separated fish images were searched for and body length was obtained by summing down the centerline segments from the head to the tail of the fish. The proposed system was verified using farmed yellowtail, Seriola quinqueradiata (mean total length 83.1 cm) to obtain a sizing error of mean total length within 2.4 cm.

The objectives of this study were to establish the method of evaluating wood mechanical properties by acoustic nondestructive testing at standing trees and at logs of a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation, and to compare three acoustic nondestructive methods for evaluating the static bending modulus of elasticity (MOE), modulus of rupture (MOR), and compressive strength parallel-to-grain (sigmasub(c)) of plantation wood as well. Fifteen Chinese fir plantation trees at 36 years of age were selected. Each tree was cut into four logs, for which three values of dynamic modulus of elasticity, i.e., Esub(sw), of the north and south face based on stress waves to assume the measuring state of the standing tree, Esub(fr), longitudinal vibration, and Esub(us), ultrasonic wave, were measured in the green condition. After log measurements, small specimens were cut and air-dried to 12% moisture content (MC). Static bending tests were then performed to determine the bending MOE and MOR, and compressive tests parallel-to-grain were made to determine sigmasub(c). The bending MOE of small clear specimens was about 7.1 % and 15.4% less than Esub(sw) and Esub(us), respectively, and 11.3% greater than Esub(fr). The differences between the bending MOE and dynamic MOE of logs as determined by the three acoustic methods were statistically significant (P 0.001). Good correlation (R

Acoustic surveys were conducted from 2002 to 2006 in the East China Sea off the Japanese coast in order to develop a quantitative classification typology of a pelagic fish community and other co-occurring fishes based on acoustic descriptors. Acoustic data were postprocessed to detect and extract fish aggregations from echograms. Based on the expert visual examination of the echograms, detected schools were divided into three broad fish groups according to their schooling characteristics and ethological properties. Each fish school was described by a set of associated descriptors in order to objectively allocate each echo trace to its fish group. Two methods of supervised classification were employed, the discriminant function analysis (DFA) and the artificial neural network technique (ANN). We evaluated and compared the performance of both methods, which showed encouraging and about equally highly correct classification rates (ANN 87.6%;DFA 85.1%). In both techniques, positional and then morphological parameters were most important in discriminating among fish schools. Fish catch composition from midwater trawling validated the fish group classification through one representative example of each grouping. Both methods provided the essential information required for assessing fish stocks. Similar techniques of fish classification might be applicable to marine ecosystems with high pelagic fish diversity.

We examined the process of microscopic fracturing peculiar to old wood, based on the generation characteristics of acoustic emission (AE) events and fracture surface analysis. The shearing tests of old wood obtained from construction-derived lumber and new wood within 3 years after lumbering were performed in accordance with the Japanese Industrial Standards (JIS Z 2101-1994). The species of wood used in this study was Japanese red pine. The old wood had been used as a beam in a building for 270 years. The number of the occurrences of AEs at low load levels was larger in the old wood than in the new wood. As a result of analyzing the AE amplitude distributions, we found that the period in which AEs with small amplitudes were frequently generated was longer in the old wood than in the new wood. Also, the fracture surfaces after the final rupture under scanning electron microscope showed more uneven and complicated surfaces in the old wood. Based on the above findings, we presume that during the shearing test the old wood underwent a relatively long and stable progress of microcracking before the final fracture.

Wood percussion instruments have been part of culture since the earliest human societies. In making an instrument, the practical experience of musical instrument makers ensures its acoustic quality, especially with respect to selecting the most suitable wood species. The aim of this study was thus to gain further insight into the relationship between the physical properties and the perceptual classification of woods to be used in xylophone-type percussion instruments. A xylophone maker perceptually classified 58 tropical wood species, most of which are not usually used for musical instruments. Dynamic tests were then performed to record radiated signals. Key signal parameters pertaining to the acoustic quality of the material were extracted. Relationships between perceptual classifications, signal parameters, and wood anatomical characteristics were thus analyzed. It has been shown that percussive acoustic quality of wood, as determined empirically by the xylophone maker, can first be related to the temporal damping of the fundamental frequency. The samples tested in this study were not musically tuned; this could explain why no frequency descriptor was relevant. However, a draft anatomical portrait of a good acoustic wood could be drawn up. The organization of wood components in the tested species highlighted the importance of the regularity and homogeneity of the anatomical structures. The axial parenchyma seems to be the key trait. It should be paratracheal, and not very abundant if possible. The rays are another important feature; they should be short, structurally homogeneous, and not very numerous.

Twenty-four different combinations of six temperatures (15°, 20°, 25°, 30°, 35°, and 40°C) and four relative humidity (RH) (60%, 70%, 80%, and 90%) conditions were used for pseudergates of the western dry-wood termite Incisitermes minor (Hagen). The feeding activities of the termites were monitored by the detection of generated acoustic emission (AE) events from feeder wood blocks in a test chamber. Temperature and RH showed independent and interactive significant effects on the feeding activity of I. minor. The optimal temperature and RH conditions for the feeding activities were 35°C and 70%, respectively, and the optimal combinations were 35°C-70% and 35°C-80% with an exceptionally higher feeding activity at the combination condition of 30°C-70%.

We tested whether pronounced morphological variability of horses caused by artificial selection was followed also by variation in their vocalization. We compared whinnies of 10 breeds representing horse varieties both in morphology and history using discrimination analyses (Wilks´ lambda = 0.070). Whinnies of Shetland pony were the most distinct from calls of other breeds (74.1% classification success). This result is in agreement with distinction based on morphological features. Whinnies of the primitive Hucul horse belonged among the most correctly classified ones (73.5%). Classification results of both Old Kladruby horse colour forms were very different: whinnies of the grey form revealed the least successful classification (18.9%) whilst calls of the black form showed one of the best classification outputs (72.4%). A surprising result was the extreme vocal distinction between the heaviest breeds, confirmed by discrimination analysis, the Czech-Moravian Belgian (55.5%), and Silesian Noriker (51.4%). This finding was contrary to their morphological similarity. The relationship between morphological and acoustical variables revealed a significant correlation. Our results did not confirm the hypothesis of acoustic distinction in horse breeds based simply on their morphology. However, whinnies of an old breed, the Shetland pony, were the most distinct ones from all the others. The other old breeds, the Thoroughbred and the Old Kladruby horses, clustered together with the modern Czech warmblood. Our results seem to not confirm the second hypothesis of vocal distinction based on the length of time since establishment of the respective breed. Significant differences among horse breeds indicate the process of vocal distinction during the process of artificial selection.

A system based on acoustic resonance was developed for eggshell crack detection. It was achieved by the analysis of the measured frequency response of eggshell excited with a light mechanism. The response signal was processed by a recursive least squares adaptive filter. Thus, the signal-to-noise ratio of the acoustic impulse response was remarkably enhanced. Five features (variables) were exacted from the response frequency signals. To develop a robust discrimination model, three pattern recognition algorithms (i.e. K-nearest neighbours, artificial neural network, and support vector machine) were examined comparatively in this work. Some parameters of the model were optimised by cross-validation in the building model. The experimental results showed that the performance of the support vector machine model is the best in comparison with k-nearest neighbours and artificial neural network models. The optimal support vector machine model was obtained with the identification rates of 95.1% in the calibration set, and 97.1% in the prediction set, respectively. Based on the results, it was concluded that the acoustic resonance system combined with the supervised pattern recognition has a significant potential for the cracked eggs detection.

Sound generated by a payao, an anchored bamboo fish aggregating device, is believed to be attractive to fish; but until now, there is no available record of payao-generated sound. This study presents payao-generated sound recorded by a hydrophone at water depths of 5, 10 and 15 m from a fixed distance of 3 m relative to the payao, and compares the sound with the auditory sensitivity of jack mackerel Trachurus japonicus measured at discrete frequencies from 100 to 2000 Hz using the auditory brainstem response protocol. A consistent peak appeared in the sound spectrum at 49 Hz and showed an increasing sound pressure level with depth, which suggests that payao sound may come from the anchor rope. However, the contribution of the bamboo raft can not yet be discounted. The hearing threshold curve indicated that the most sensitive frequency range in jack mackerel is from 92.1 dB at 800 Hz to 111.0 dB at 200 Hz. These results show that the dominant frequency range of payao sound does not correspond with the high sensitivity frequency range of fish hearing.

:  Measurement theory and method of the bottom surface backscattering strength (SS) using a quantitative echo sounder (QES) are discussed and applied in the ocean near Java, Indonesia. The frequencies of the QES were 38, 70, and 120 kHz. The measurements of bottom echoes and sampling of bottom material by a dredge were done simultaneously. Bottom characterization was based on analysis of particle size distribution for bottom samples taken during the survey. The SS value increases with the increase of the mean diameter of the bottom particles. The SS decreased with increasing frequency. The effectiveness of QES for measurement of the SS along with observation of the depth topography were demonstrated.