Dolphins Underwater Sounds Database: Preliminary Analysis Results

The present paper treats the signal recording and the preliminary analysis of the vocalization of five Caribbean bottlenose dolphins (Tursiops Truncates) in the controlled aquatic environment – a dolphinarium water pool. The data are taken using measurement equipment from the world's leading companies – Brüel&Kjær and National Instruments Corporation. All records have been denoised and segmented in advance so that only the vocal-active parts to be analyzed. The most representative part of the records and analysis results are deposited in one of world's most reputable databases – IEEE DataPort™, under the name "Dolphins Underwater Sounds Database". All analyses are conducted in the Matlab environment, thus they include: signal oscillogram, overall frequency spectrum, time-frequency spectrogram, time-quefrency cepstrogram and also signal correlogram and amplitude histogram. The report is rich in figures that represent some of the most interesting results. Finally, some common conclusions are drawn, based on the analysis results, and along with considerations for feature work.

Improving bedload transport determination by grain-size fraction using the Swiss plate geophone recordings at the Erlenbach stream

Direct bedload samples were taken with a large metal basket at the steep Erlenbach stream in Switzerland. These measurements were compared with the signal of the Swiss impact plate geophone system to derive information about bedload transport. The so-called amplitude histogram (AH) method was developed in an earlier study to estimate the bedload flux for different grain-size classes at the Erlenbach. A new analysis of a larger set of measurements was made here to improve the performance of the AH method. The approach relies on an identification of the transported grain sizes through their dependency on the signal amplitude. As a new element we introduce here the impulse rate, which is found to affect the number of impulses recorded for each amplitude class. As compared to the original method, the new version of the AH method shows a slightly improved performance for total calculated bedload mass, and results in a clearly better agreement between calculated and measured characteristic grain sizes.

Fault Diagnosis of Bearing Based on the Ultrasonic Amplitude Histogram

The bearing of rotating machine often fails due to the frictional forces of rolling element, such frictional forces often generate a series of ultrasound, and that is to say, there must be some necessary relationships between the faults of rotating machinery equipment and the ultrasound from the equipment. In this paper, the histogram method which is the simplest method in statistics is used to analyze the ultrasonic signals. Through the analysis, the bearing faults could be preliminarily diagnosed. A verification research with respect to vibration method is carried out to analyze the effectiveness and superiority of ultrasonic method by using the histogram. Extensive experiments have been performed in a bearing vibration measuring instrument, and the results indicated that the fault diagnosis method based on the ultrasonic amplitude histogram is more useful than the method based on the vibration amplitude histogram. In addition, it is more sensitive and more effective than the method based on vibration amplitude histogram.

Depolarization-Induced Ca2+ Entry Preferentially Evokes Release of Large Quanta in the Developing Xenopus Neuromuscular Junction

The amplitude histogram of spontaneously occurring miniature synaptic currents (mSCs) is skewed positively at developing Xenopus neuromuscular synapses formed in culture. To test whether the quantal size of nerve-evoked quanta (eSCs) distributes similarly, we compared the amplitude histogram of single quantum eSCs in low external Ca2+ with that of mSCs and found that nerve stimulation preferentially released large quanta. Depolarization of presynaptic terminals by elevating [K+] in the external solution or by direct injection of current through a patch pipette increased the mSC frequency and preferentially, but not exclusively, evoked the release of large quanta, resulting in a second broad peak in the amplitude histogram. Formation of the second peak under these conditions was blocked by the N-type Ca2+ channel blocker, ω-conotoxin GVIA. In contrast, when the mSC frequency was elevated by thapsigargin- or caffeine-induced mobilization of internal Ca2+, formation of the second peak did not occur. We conclude that the second peak in the amplitude histogram is generated by Ca2+ influx through N-type Ca2+ channels, causing a local elevation of internal Ca2+. The mSC amplitude in the positively skewed portion of the histogram varied over a wide range. A competitive blocker of acetylcholine (ACh) receptors, d-tubocurarine, reduced the amplitude of smaller mSCs in this range relatively more than that of larger mSCs, suggesting that this variation in the mSC amplitude is due to variable amounts of ACh released from synaptic vesicles. We suggest that Ca2+ influx through N-type Ca2+ channels preferentially induces release of vesicles with large ACh content.