scholarly journals THE FEATURES OF THE COMBINED RECEIVER UNIT OPERATION ABOARD UNDERWATER GLIDER

2020 ◽  
Author(s):  
Б.А. Касаткин ◽  
С.Б. Касаткин
Keyword(s):  
Sound Pressure ◽  
Sound Field ◽  
Aquatic Area ◽  
Unit Operation ◽  
Underwater Glider ◽  
Informative Parameters ◽  
Intensity Vector ◽  
Receiver System ◽  
Combined Receiver ◽  
Receiver Unit

При работе приемной системы на борту движущегося носителя возникает специфическая проблема уменьшения собственных шумов носителя, уровень которых зависит от типа приемной системы и алгоритмов обработки сигналов. В настоящей работе рассматриваются особенности работы комбинированного приемника на борту подводного планера (глайдера) в собственных шумах обтекания, которые возникают при изменении горизонта позиционирования глайдера. Предложено полное описание энергетической структуры звукового поля, включающее 16 информативных параметров. В их число входят квадрат звукового давления, компоненты комплексного вектора интенсивности, компоненты вещественного ротора вектора интенсивности и квадратичные компоненты комплексного вектора градиента давления. Приводятся результаты натурного эксперимента, выполненного в мелком море, в котором глайдер, оснащенный комбинированным приемником, периодически изменял горизонт позиционирования в режиме погружение – всплытие. Анализируются в сравнительном плане уровни шумов обтекания на выходе канала звукового давления и на выходе векторных каналов при различном определении информативных параметров, характеризующих звуковое поле в скалярно-векторном описании. Приводятся оценки уровня шумов обтекания, подтверждающие преимущества комбинированного приемника в сравнении с гидрофоном при его работе в составе бортовой приемной системы в ближнем поле собственных шумов обтекания. Рассматриваются особенности работы комбинированного приемника на борту подводного планера (глайдера) в собственных шумах обтекания, которые возникают при изменении горизонта позиционирования глайдера. Анализируются в сравнительном плане уровни шумов обтекания на выходе канала звукового давления и на выходе векторных каналов при различном определении информативных параметров, характеризующих звуковое поле в скалярно-векторном описании. Приводятся результаты натурного эксперимента, подтверждающие преимущества комбинированного приемника в сравнении с гидрофоном при его работе в составе бортовой приемной системы в ближнем поле собственных шумов обтекания. While operating aboard moving carrier, the receiver system faces a specific problem of reducing self-noises of the carrier, the magnitude of which depends on the type of receiver system and algorithms of signal processing. The present work considers the features of the combined receiver unit operation aboard underwater glider in self-generated flow noises, originated when the glider positioning horizon is changed. The complete description of the energetic structure of the sound field, including 16 informative parameters, is proposed. The list of parameters includes sound pressure squared, components of the complex intensity vector, components of the real curl of an intensity vector, and quadratic components of the complex vector of the pressure gradient. The theoretical background is supported by the results of the marine trials conducted in the shallow aquatic area. In it, the underwater glider equipped with the combined receiver unit sequentially changed the positioning horizon in the “submerging-emerging” mode. The levels of flow noise on the output of the sound pressure channel and the output of the vector channel are comparatively analyzed for different determinations of informative parameters, characterizing the sound field in the scalar-vector description. The presented estimates of flow noises levels confirm the advantages of a combined receiver unit compared to a hydrophone while operating as a part of the on-board receiver system in a near field on self-generated flow noises.

scholarly journals МОДУЛЯЦИЯ ПОЛЯ ПОГРАНИЧНЫХ ВОЛН ВНУТРЕННИМИ ВОЛНАМИ В ПЕРЕХОДНОЙ ЗОНЕ  ШЕЛЬФ - ГЛУБОКОЕ МОРЕ

2019 ◽  
Author(s):  
B.A. Kasatkin ◽  
S.B. Kasatkin
Keyword(s):  
Internal Waves ◽  
Experimental Studies ◽  
Sound Field ◽  
Modulation Amplitude ◽  
Periodic Modulation ◽  
Frequency Range ◽  
Interference Structure ◽  
Intensity Vector ◽  
Power Spectral ◽  
Combined Receiver

Приведены результаты экспериментальных исследований влияния внутренних волн на интерференционную структуру звукового поля, сформированного пограничными волнами Релея Шолте в переходной зоне шельф глубокое море. Это влияние проявляется в периодической модуляции частоты максимума спектральной плотности мощности на сонограммах звукового поля, зарегистрированных комбинированным приёмником, в инфразвуковом диапазоне частот, причём амплитуда модуляции пропорциональна частоте. Анализируется зависимость периода модуляции от взаимного расположения приёмных модулей, шумящего судна, формирующего звуковое поле дискретными составляющими вально лопастного звукоряда, и предполагаемого направления распространения внутренних волн. Отмечено, что наибольшее влияние внутренние волны оказывают на структуру вихревой составляющей вектора интенсивности.The results of experimental studies of the influence of internal waves on the interference structure of the sound field formed by the RayleighSholte boundary waves in the transition zone of the shelf deep sea are presented. This effect is manifested in the periodic modulation of the frequency of the maximum of the power spectral density in the sonograms of the sound field recorded by the combined receiver in the infrasonic frequency range, with the modulation amplitude proportional to the frequency. The dependence of the modulation period on the relative position of the receiving modules, the noisy vessel that forms the sound field by the discrete components of the vane blade scale, and the expected direction of propagation of internal waves is analyzed. It is noted that internal waves have the greatest effect on the structure of the vortex component of the intensity vector.

scholarly journals МОДУЛЯЦИЯ ПОЛЯ ПОГРАНИЧНЫХ ВОЛН ВНУТРЕННИМИ ВОЛНАМИ В ПЕРЕХОДНОЙ ЗОНЕ  ШЕЛЬФ - ГЛУБОКОЕ МОРЕ

2019 ◽  
Author(s):  
B.A. Kasatkin ◽  
S.B. Kasatkin
Keyword(s):  
Internal Waves ◽  
Experimental Studies ◽  
Sound Field ◽  
Modulation Amplitude ◽  
Frequency Range ◽  
Interference Structure ◽  
Intensity Vector ◽  
Vector Sensor ◽  
Power Spectral ◽  
Combined Receiver

Приведены результаты экспериментальных исследований влияния внутренних волн на интерференционную структуру звукового поля, сформированного пограничными волнами Релея Шолте в переходной зоне шельф глубокое море. Это влияние проявляется в периодической модуляции частоты максимума спектральной плотности мощности на сонограммах звукового поля, зарегистрированных комбинированным приёмником, в инфразвуковом диапазоне частот, причём амплитуда модуляции пропорциональна частоте. Анализируется зависимость периода модуляции от взаимного расположения приёмных модулей, шумящего судна, формирующего звуковое поле дискретными составляющими вально лопастного звукоряда, и предполагаемого направления распространения внутренних волн. Отмечено, что наибольшее влияние внутренние волны оказывают на структуру вихревой составляющей вектора интенсивности. Ключевые слова: внутренние волны, пограничные волны, инвариант, комбинированный приёмник, сонограмма.The results of experimental studies of the influence of internal waves on the interference structure of the sound field formed by the RayleighSholte boundary waves in the transition zone of the shelf deep sea are presented. This effect is manifested in the periodic modulation of the frequency of the maximum of the power spectral density in the sonograms of the sound field recorded by the combined receiver in the infrasonic frequency range, with the modulation amplitude proportional to the frequency. The dependence of the modulation period on the relative position of the receiving modules, the noisy vessel that forms the sound field by the discrete components of the vane blade scale, and the expected direction of propagation of internal waves is analyzed. It is noted that internal waves have the greatest effect on the structure of the vortex component of the intensity vector. Keywords: internal waves, boundary waves, invariant, combined receiver (acoustic vector sensor), sonogram.

Active control of the scattered radiation with a reflecting surface

2019 ◽  
Vol 67 (3) ◽  
pp. 190-196
Author(s):  
Ning Han
Keyword(s):  
Control System ◽  
Active Control ◽  
Scattered Radiation ◽  
Sound Pressure ◽  
Sound Field ◽  
Control Area ◽  
Mirror Image ◽  
Three Dimension ◽  
Control Effect ◽  
Reflecting Surface

Based on a prediction method of the scattered sound pressure, an active control system was proposed in previous work for the three-dimension scattered radiation, where all the relevant simulations and experiments were implemented in three-dimensional free sound field. However, for practical applications, such as the anti-eavesdropping system or the stealth system for submarines, the sound field conditions are usually complex, and the most common case is the one with reflecting surface. It is questionable whether the previous control system is still effective in non-free sound field, or what improvements should be operated to ensure the control effect. In this article, based on the mirror image principle, two methods of calculating the control source strengths are proposed for the scattered radiation control, and numerical simulations with one-channel and multi-channel system are implemented to detect the corresponding control effect. It is seen that the local active control for the scattered radiation is still effective, and the reduction of the sound pressure level as well as the control area is extended with the increasement of the error sensors and control sources.

scholarly journals Research on the Manufacturing Quality of Co-Cured Hat-Stiffened Composite Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2747
Author(s):  
Xiangwen Ju ◽  
Jun Xiao ◽  
Dongli Wang ◽  
Cong Zhao ◽  
Xianfeng Wang
Keyword(s):  
Composite Structures ◽  
Sound Pressure ◽  
Integration Method ◽  
Complex Geometry ◽  
Sound Field ◽  
Thickness Measurement ◽  
Curing Process ◽  
The Finite Element Method ◽  
Manufacturing Quality

The stringer-stiffened structure is widely used due to its excellent mechanical properties. Improving the manufacturing quality of stringer-stiffened structure which have complex geometry is important to ensure the bearing capacity of aviation components. Herein, composite hat-stiffened composite structures were manufactured by different filling forms and bladders with various properties, the deformation of silicone rubber bladder in co-curing process was studied by using the finite element method. The thickness measurement at different positions of the hat-stiffened structure was performed to determine the best filling form and bladder property. Moreover, in view of the detection difficulties in R-zone of stringer, numerical simulation was performed to get the sound pressure and impulse response of at the R-zone of stringer by Rayleigh integration method, and an effective equipment which could stably detect the manufacturing quality of R-zone was designed to verify the correctness of sound field simulation and realize the detection of stringer. With the optimum filling form and bladder properties, hat-stiffened composites can be manufactured integrally with improved surface quality and geometric accuracy, based on co-curing process.

scholarly journals Mathematical modeling and experimental study on solid–liquid suspension separation in ultrasonic standing wave field

2021 ◽  
pp. 146134842110229
Author(s):  
Yajing Wang ◽  
Liqun Wu ◽  
Yaxing Wang ◽  
Yafei Fan
Keyword(s):  
Standing Wave ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Sound Field ◽  
Radiation Force ◽  
High Energy ◽  
Factors Affecting ◽  
Liquid Suspension ◽  
Ultrasonic Standing Wave ◽  
Solid Liquid

A new method of removing waste chips is proposed by focusing on the key factors affecting the processing quality and efficiency of high energy beams. Firstly, a mathematical model has been established to provide the theoretical basis for the separation of solid–liquid suspension under ultrasonic standing wave. Secondly, the distribution of sound field with and without droplet has been simulated. Thirdly, the deformation and movement of droplets are simulated and tested. It is found that the sound pressure around the droplet is greater than the sound pressure in the droplet, which can promote the separation of droplets and provide theoretical support for the ultrasonic suspension separation of droplet; under the interaction of acoustic radiation force, surface tension, adhesion, and static pressure, the droplet is deformed so that the gas fluid around the droplet is concentrated in the center to achieve droplet separation, and the droplet just as a flat ball with a central sag is stably suspended in the acoustic wave node.

Study on Sound Field of High Intensity Focused Ultrasound with Short Focal Length

2012 ◽  
Vol 195-196 ◽  
pp. 364-369 ◽  
Author(s):  
Jin Hua Zhao ◽  
Li Li Yu ◽  
Chun Hui ◽  
Bin Feng Huang ◽  
Chao Li ◽  
...  
Keyword(s):  
Nonlinear Effect ◽  
Sound Pressure ◽  
Focal Length ◽  
Sound Field ◽  
High Intensity Focused Ultrasound ◽  
Beam Equation ◽  
Focal Region ◽  
Interface Position ◽  
Short Focal Length ◽  
Planar Wave

In this paper, numerical simulation of sound field with short focal length is performed, which is based on spheroidal beam equation (SBE) in frequency-domain for transducer with a wide aperture angle. And we made some experiments on vitro bovine liver to explore the characteristic of sound pressure and-3dB sound focal region at different positions of incident interface. It is found that with a fixed curvature radius if the focal length is shorter under the skin, the amplitude of sound pressure will be higher on the focus and the shape of-3dB sound focal region will be smaller. When the incident interface is in the range of planar wave, nonlinear effect is strong and the focus will change with the interface position. Especially when the position is near to transition location between planar wave and spheroidal wave, the nonlinear effect is lowered. While the focus is closer to the sound source so as to burn the scarfskin easily. When the interface is in the range of spheroidal wave, the focus position changes little but the side lobe effect due to refraction is obvious. And the focusing performance of transducer will be affected. The experimental results validate the accuracy of theoretical results. It is concluded that the position of incident interface should be selected reasonably with short focal length in the treatment of superficial tissue.

Interaction between Strong Sound Waves and Cloud Droplets: Theoretical Analysis

2021 ◽  
Author(s):  
Ying-Hui Jia ◽  
Fang-Fang Li ◽  
Kun Fang ◽  
Guang-Qian Wang ◽  
Jun Qiu
Keyword(s):  
Sound Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Field ◽  
Pressure Level ◽  
Velocity Variation ◽  
Time Range ◽  
Sound Waves ◽  
Cloud Droplets ◽  
Acoustic Frequency

AbstractRecently strong sound wave was proposed to enhance precipitation. The theoretical basis of this proposal has not been effectively studied either experimentally or theoretically. Based on the microscopic parameters of atmospheric cloud physics, this paper solved the complex nonlinear differential equation to show the movement characteristics of cloud droplets under the action of sound waves. The motion process of individual cloud droplet in a cloud layer in the acoustic field is discussed as well as the relative motion between two cloud droplets. The effects of different particle sizes and sound field characteristics on particle motion and collision are studied to analyze the dynamic effects of thunder-level sound waves on cloud droplets. The amplitude of velocity variation has positive correlation with Sound Pressure Level (SPL) and negative correlation with the frequency of the surrounding sound field. Under the action of low-frequency sound waves with sufficient intensity, individual cloud droplets could be forced to oscillate significantly. The droplet smaller than 40μm can be easily driven by sound waves of 50 Hz and 123.4 dB. The calculation of the collision process of two droplets reveals that the disorder of motion for polydisperse droplets is intensified, resulting in the broadening of the collision time range and spatial range. When the acoustic frequency is less than 100Hz (@ 123.4dB) or the Sound Pressure Level (SPL) is greater than 117.4dB (@ 50Hz), the sound wave can affect the collision of cloud droplets significantly. This study provides theoretical perspective of acoustic effect to the microphysics of atmospheric clouds.

Lightweight Research of Automobile Dash Panel Based on Sound-Structure Sensitivity

2013 ◽  
Vol 681 ◽  
pp. 200-203 ◽  
Author(s):  
Lei Zhang ◽  
Zhi Yong Hao
Keyword(s):  
Sound Pressure ◽  
Lightweight Design ◽  
Sound Field ◽  
Coupling Model ◽  
Structure Sensitivity ◽  
Car Body ◽  
Field Coupling ◽  
Sound Structure ◽  
Dash Panel

In the research of the automobile front dash, the key of design is that acoustic need should be satisfied while losing the weight. In this paper, a structure-sound field coupling model of car body space is built. To fulfill the request, the dash panel is divided into several parts, and the sensitivity of thickness of each parts to the sound at the position of driver’s and co-pilot’s ears is calculated. Based on the sensitivity, the driver’s and the co-pilot’s parotic sound pressure is optimized while reducing the weight of front dash. The result proves that lightweight design is successful, which gives the reference to the design of the car body panels.

scholarly journals A Finite-Difference Wavenumber-Time Domain Method for Sound Field Prediction in a Uniformly Moving Medium

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bichun Dong ◽  
Runmei Zhang ◽  
Chuanyang Yu ◽  
Huan Li
Keyword(s):  
Finite Difference ◽  
Time Domain ◽  
Sound Pressure ◽  
Sound Field ◽  
Time Domain Method ◽  
Practical Significance ◽  
Moving Medium ◽  
Domain Method ◽  
Aero Engines ◽  
The Stability

Sound field prediction has practical significance in the control of noise generated by sources in a flow, for example, the noise in aero-engines and ventilation systems. Aiming at accurate and flexible prediction of time-dependent sound field, a finite-difference wavenumber-time domain method for sound field prediction in a uniformly moving medium is proposed. The method is based on the second-order convective wave equation, and the wavenumber-time domain representation of the sound pressure field on one plane is forward propagated via a derived recursive expression. In this paper, the recursive expression is first deduced, and then numerical stability and dispersion of the proposed method are analyzed, based on which the stability condition is given and the correction of dispersion related to the transition frequency is made. Numerical simulations are conducted to test the performance of the proposed method, and the results show that the method is valid and robust at different Mach numbers.

scholarly journals A System for Acoustic Field Measurement Employing Cartesian Robot

2016 ◽  
Vol 23 (3) ◽  
pp. 333-343 ◽  
Author(s):  
Maciej Szczodrak ◽  
Adam Kurowski ◽  
Józef Kotus ◽  
Andrzej Czyżewski ◽  
Bożena Kostek
Keyword(s):  
Acoustic Field ◽  
Energy Flow ◽  
Velocity Vector ◽  
Sound Pressure ◽  
Sound Field ◽  
Acoustic Energy ◽  
The Other ◽  
Object Shape ◽  
Movement Path ◽  
Optimum Path

AbstractA system setup for measurements of acoustic field, together with the results of 3D visualisations of acoustic energy flow are presented in the paper. Spatial sampling of the field is performed by a Cartesian robot. Automatization of the measurement process is achieved with the use of a specialized control system. The method is based on measuring the sound pressure (scalar) and particle velocity(vector) quantities. The aim of the system is to collect data with a high precision and repeatability. The system is employed for measurements of acoustic energy flow in the proximity of an artificial head in an anechoic chamber. In the measurement setup an algorithm for generation of the probe movement path is included. The algorithm finds the optimum path of the robot movement, taking into account a given 3D object shape present in the measurement space. The results are presented for two cases, first without any obstacle and the other - with an artificial head in the sound field.

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