[Show abstract][Hide abstract] ABSTRACT: Main problems of application of vector sensors (VSs) for flexible towed arrays are providing high performance under small dimensions as well as necessary flow noise immunity. The objective is to develop VSs to meet thee demands. A simulation of performance of VS embedded in a flexible towed array body formed with sound transparent compound is performed. The developed onedimensional model, predicts existence of a suspension resonance, dividing frequency band of VS into two parts. The lower part of the band is more applicable for VS of inertial type while the upper one is more preferred for VS of gradient type A possibility to control the suspension resonance frequency in limits of 500-2000 Hz is shown for experimental model. The flow noise immunity problem is analyzed for different frequency bands and type of VSs. Various methods of flow noise cancellation are developed for different frequency bands and types of VSs, which include power flux processing, compensation of vibration response, convolution processing. Examples of design of one- and twocomponent VSs are represented. The study is supported by the grant 13-NTP-II-08 of Far Eastern Branch of Russian Academy of Sciences.
[Show abstract][Hide abstract] ABSTRACT: A video measuring installation for registering low-frequency acoustic vibrations in two orthogonal directions with conversion of the results into a WAV-format file is described. The capabilities of the system in the detection of test mechanical vibrations at a frequency of 300 Hz were experimentally studied. The resolution of the system is 3 μm, and its dynamic range is 23 dB. The installation can be used in studies of vibrations of engineering and natural objects.
Full-text · Article · Jan 2014 · Instruments and Experimental Techniques
[Show abstract][Hide abstract] ABSTRACT: New technologies of hidden bronchial obstruction diagnostics are necessary for respiratory medicine. Objective of this study is developing computer technology and instrumentation to reveal bronchial obstruction by means of tracheal forced expiratory noises analysis. The technology has been designed which is based on computer measuring forced expiratory tracheal noises duration. The apparatus has been developed which contains acoustic sensor, input device, portable personal computer and specially designed software. The sensor is attached to lateral neck surface. It was found that forced expiratory tracheal noises duration is directly connected with bronchial resistance of forced exhalation. Experimental estimation of efficiency of forced expiratory tracheal noises duration as diagnostic test of bronchial obstruction in the model of spirometry approved bronchial asthma revealed quite high sensitivity and specificity which were comparable with basic spirometry index (FEV1/FVC) sensitivity and specificity. Furthermore about 40% of patients with hidden bronchial obstruction (spirometry negative bronchial asthma) were diagnosed by means of forced expiratory tracheal noises duration. The technology was also successfully used for monitoring lung function of divers after immersion. Thus developed technology and instrumentation is informative, simple, very cheap, and it is promising for application in pulmonary function testing.
[Show abstract][Hide abstract] ABSTRACT: The objective of this work is to simulate the flow noise of a vector sensor embedded in a flexible towed array. The mathematical model developed, based on long-wavelength analysis of the inner space of a cylindrical multipole source, predicts the reduction of the flow noise of a vector sensor embedded in an underwater flexible towed array by means of intensimetric processing (cross-spectral density calculation of oscillatory velocity and sound-pressure-sensor responses). It is found experimentally that intensimetric processing results in flow noise reduction by 12-25 dB at mean levels and by 10-30 dB in fluctuations compared to a squared oscillatory velocity channel. The effect of flow noise suppression in the intensimetry channel relative to a squared sound pressure channel is observed, but only for frequencies above the threshold. These suppression values are 10-15 dB at mean noise levels and 3-6 dB in fluctuations. At towing velocities of 1.5-3 ms(-1) and an accumulation time of 98.3 s, the threshold frequency in fluctuations is between 30 and 45 Hz.
Full-text · Article · May 2012 · The Journal of the Acoustical Society of America
[Show abstract][Hide abstract] ABSTRACT: A complexity of respiratory path structure has already caused assumptions on existence of several ways of sound transmission from mouth to chest wall. The objective is a study of these mechanisms. The studied sample included 25 healthy subjects. They breathed with room air, helium‐oxygen, and krypton‐oxygen gas mixtures which had various sound velocities. Phase manipulated and frequency sweep signals were injected into mouth. Signals transmitted to chest wall sites (bottom part of trachea and basal area of right lung) were recorded by accelerometers. A convolution procedure was carried out. At least two signal arrivals are recognized in each convolution curve recorded above basal area for any gas mixture. One main arrival is recognized above trachea, which times are statistically dependent on gas mixture for all signals. The first arrival times above basal area of lung are also dependent on gas mixture. However, the second arrival times above basal area of lung are independent of gas mixture. Thus the arrival above trachea and the first arrival above basal area of lung, being dependent on filling gas sound velocity, are transmitted through airways lumen at least in part of their path. Alternatively the second arrival recorded above basal area of lung, being independent of filling gas sound velocity, seems to be transmitted through lung parenchyma. [The study was supported by RFBR grant 09‐08‐00105.]
Full-text · Article · Apr 2011 · The Journal of the Acoustical Society of America
[Show abstract][Hide abstract] ABSTRACT: Diving renders negative influence on human respiratory system especially when oxygen breathing apparatus aimed for military divers is used. Spirometry indexes have poor sensitivity to toxic effect of hyperbaric hyperoxia. Objective is to develop new acoustic instrumentation for revealing minimum impairments of lung function in oxygen divers. The apparatus has been designed which is based on analysis of forced expiratory tracheal noise duration (FETND). This apparatus contains acoustic sensor, input device, portable personal computer and specially designed software. 48 divers before and after single shallow water dive in oxygen closed-type breathing apparatus were tested by means of this acoustic tool. After dive a significant drop of spirometric indexes forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) over the group as a whole was found. The significant increase of individual FETND, exceeding the natural variability limit, was found in 10 subjects (20.8%). Three of them during dive had respiratory symptoms characteristic for initial manifestations of pulmonary oxygen poisoning. Two of them had essential drop of FEV1. The asymptomatic reversible increase of FETND in the rest 7 divers was interpreted as a sign of obstructive impairments caused by hidden phase of hyperbaric hyperoxia effect. Thus developed acoustic tool is useful to monitor ventilation function of lungs in military/civil divers and other persons working in harmful gas media such as firefighters, astronauts and so on.
[Show abstract][Hide abstract] ABSTRACT: We develop a laboratory setup to estimate the force of rotation of a metal branch pipe in a viscoelastic medium. We show that
2-min action of shearing ultrasonic oscillations (frequency, 32.5 kHz; specific power, no more than 0.008 W/cm2) reduces by 17% the static limit of fluidity brought to an initial temperature of Ì-100 fuel oil cooled to −15°C in the wall
layer of a rotating branch pipe. We obtain a linear regression dependence between the ratio of the threshold force of the
onset of branch pipe motion to the consumption current of the ultrasonic transducer and the fuel temperature.
No preview · Article · Sep 2010 · Acoustical Physics
[Show abstract][Hide abstract] ABSTRACT: Lumen probing of human lungs with complex acoustic signals in the frequency band from 100 to 1000 Hz made it possible for
the first time to explicitly confirm the concurrent existence of two mechanisms differing in propagation velocity behind the
transmission of acoustic vibrations from the oral cavity to the thoracic cage surface. The numerical values of propagation
time lags allowed one of these mechanisms to be associated with combined aerial-structural transmission and the other, with
purely structural transmission.
No preview · Article · Jul 2010 · Acoustical Physics
[Show abstract][Hide abstract] ABSTRACT: Laboratory installation for acoustic sounding of human lungs by complex signals has been developed. Linear frequency sweep
signal (80-1000 Hz, 20 s) and the signal containing m-coded (the basis - 511 readouts) phase-manipulated fragments with three
various carrying frequencies (200, 300, 750 Hz) are entered into mouth. Pilot experiment has been carried out with 3 volunteers.
Results of processing of sounding signals received on the chest surface by convolution method show, that the pictures of arrivals
of sounding signal are various above the top, middle and basal areas of lungs, and have steady (replicating from attempt to
attempt and from one kind of signals to another) specific features connected with time delays of arrivals, ratio of amplitudes
of maxima of arrivals. In basal areas of lungs two various arrivals of both sounding signals have been directly found. This
testifies to existence, at least, two various ways of sound transmission in human lungs, distinguished on resulting sound
velocity of mechanical oscillations. Subject’s individuality, dependent on body build and age related condition of lung parenchyma,
was found both in time delays between emission of sounding signal and reception of the first arrival, and time delays between
the first and the second arrivals. The developed method seems to be promising for non ionizing transmission low frequency
acoustic tomography of lungs.
[Show abstract][Hide abstract] ABSTRACT: Within the framework of a specified acousto-biomechanical model, a possibility of explaining wheezes during forced expiration on the basis of a vortex separation mechanism is tested and the localization of the zones in the bronchial tree where forced expiratory wheezes are generated is refined. As an experimental model, a group of 18 healthy volunteers from 18 to 44 years old (median is equal 19) was used. On the basis of linear regression modeling the relationship between the principal spectral frequency of medium-frequency forced expiratory wheezes (400–600 Hz) recorded on the trachea and the standard volume flow-rates of expired air measured in computer spirometry is analyzed. The data obtained show that vortex separation in the air flow at the bronchial tree bifurcations (where a stepwise increase in the cross-section area takes place) is a probable mechanism of medium-frequency forced expiratory wheeze generation and that during the forced expiratory maneuver the vortex separation zone tends to be displaced deeper into the bronchial tree.
[Show abstract][Hide abstract] ABSTRACT: The authors developed a method for more precise detection and analysis of the physical features of respiratory and voice sound transmission to the chest wall. Based on their findings using this method, they designed several devices for acoustic examination and evaluation of components of human respiratory sounds. These devices analyze forced expiratory sounds, distinguish between air-borne and structure-borne sounds, and distinguish abnormalities in voice transmission to the chest wall. Tests of the devices on human subjects confirmed the validity of the authors' theoretical models, which offer promise for the development of a new class of medical diagnostic instruments.