71 results about "Underwater noise" patented technology

Air bubbles may be used to reduce radiated underwater noise. Two modalities of sound attenuation by air bubbles were shown to provide a reduction in radiated sound: bubble acoustic resonance damping and acoustic impedance mismatching. The bubbles used for acoustic resonance damping were manifested using gas-filled containers coupled to a support, and the acoustic impedance mismatching bubbles were created using a cloud of freely-rising bubbles, which were both used to surround an underwater sound source.

The invention provides a blind source signal denoising method based on ensemble empirical mode decomposition, and belongs to the technical field of signal processing. By means of the method, definitions on the white noise amplitude and the number of iterations in an original algorism are rectified. False component discrimination is conducted on the IMP component obtained after IEEMD is decomposed through a classic stepwise regression analysis method, features of original signals are effectively reserved, the false component generated by the IEEMD algorism is eliminated, and interference to the subsequent denoising algorism by the false component is eliminated. Finally, for the non-convergence phenomenon generated occasionally when the ICA algorism processes the high-frequency signals, a high-order TFastICA method is provided, features of the IEEMD and the TFastICA are combined, and rear-end processing is conducted on the IEEMD through the TFastICA method. The blind source signal denoising method based on the ensemble empirical mode decomposition has wide application prospects in the fields of removing mechanical vibration noise, voice signal noise, instantaneous underwater noise and other signal processing fields.

The invention discloses a self-noise test system and level test method for a ship sonar platform and belongs to the field of underwater noise control engineering. According to the invention, three signal source generators are controlled through a computer to generate excitation signals, and so the three signal source generators generate simulated hydrodynamic noise, simulated mechanical noise andsimulated propeller noise. Then data is collected and analyzed through a signal acquisition and recording end. A sonar platform self-noise test under a single noise resource effect can be carried out,a platform self-noise test under the effects of multiple noise resources at the same time can be implemented, test data in a whole wide frequency band can be obtained at a time, tests in different frequency bands are avoided, the work efficiency is improved, and the self-noise characteristics of a sonar chamber under various working conditions are more realistically simulated, and the establishment of a self-noise test system for the ship sonar platform is achieved.

A recoverable subsurface buoy recorder for underwater noise is a system which has both functions of remote control and automatic control as it is composed of subsurface buoy, releasing device, and anchoring block. The system can be on duty under water depth of 300 m for long-term and can record underwater noise at range of 1 herts to 100 kiloherts on real time according to preprogram command or abovewater remote command at any time.

The invention provides a feature extraction method of a radiated noise signal of an underwater target, comprising the steps of: firstly researching a visualization method of an acoustic signal to obtain a time-frequency visual image; then carrying out visual feature extraction method research including feature extraction and image centre torque feature extraction based on image texture by regarding a spectrogram in the time-frequency visual image as a searched object; on the basis, respectively utilizing principal component analysis (PCA) and linear discrimination analysis (LDA) algorithms to carry out optimal selection and dimension reduction on the visual feature obtained by the method, and finally applying the visual feature to simulation of underwater target identification. The experimental results show that the average recognition rates of three types of underwater noise signals under the mixed feature can be up to 91.97%, and the recognition rates of the selected visual feature parameters are obviously improved compared with the feature parameters extracted by the conventional method.

The invention provides a course angle rotation-based multi-beam side-scan sonar image real-time splicing method. The method comprises the following steps of: acquiring initial data in all channels of a multi-beam side-scan sonar, and setting an initial position for splicing images; removing a water column area generated because an energy transducer receives an underwater noise before a first echo point returns; writing N channel data of the first ping in the initial data from which the water column area is removed into a canvas, and recording the current ping number and the current course angle; reading N channel data of the next ping and corresponding global positioning system (GPS) and course angle information, calculating the difference value between the course angles of the first ping and the next ping, if the course angle does not change, splicing the images in sequence according to the GPS information, and if the course angle changes, splicing the images after rotating the data, wherein the rotating angle is the difference value between the course angels; and modifying gaps in the spliced image. The invention discloses a multi-beam side-scan sonar image real-time splicing method which is high in precision and low in calculation amount and has a good display effect.

The invention discloses a tuna tracking float acoustic anti-theft device. A tracking float is used for fixing driftwood used for tuna seine catching. The tracking float is a satellite tracking floating float, and is composed of a satellite transceiver, a GPS, a fathometer used for probing fish schools, a temperature sensor, a magnetic switch, a solar cell panel and or a storage battery and a solid shell. The acoustic anti-theft device is arranged in the tracking float and is provided with a hydrophone used for monitoring noise under water, the output end of the hydrophone is sequentially connected with a signal amplifier, a band-pass filter, an A / D converter and a DSP micro processor, and the DSP micro processor carries out feature extraction and goal recognition on the noise under water according to a stored underwater noise sound feature library and a mode recognition library of a conventional ship engine.

The invention relates to a breaststroke underwater propulsion system which provides advancing power for an underwater apparatus in a frog simulating underwater motion way, drives a pull rod by a piston so as to drive an upper end framework and a lower end framework, enables the upper end framework, the lower end framework and the pull rod to interact by a lever principle so as to drive frog feet to move and provide advancing power for the underwater apparatus. The breaststroke underwater propulsion system has simpler structure, low underwater noise level, no wake flow, high concealment performance and lower manufacturing and using cost and is a potential underwater propulsion system.

The invention provides a vector array steady focusing processing method with a combined constraint optimization form. The method comprises the following steps of: (a) generating a vector array data matrix Sv(r, theta, phi); (b) obtaining a sampled data covariance matrix R<(v)> having a symmetrical structure, and performing Cholesky decomposition on the R<(v>) to obtain a Cholesky decomposition factor U<(v)>; (c) generating vector array focusing-oriented vectors of different scanning positions; (d) applying a steady combined constraint optimization condition to the vector array focusing-oriented vectors and the decomposition factor U<(v)>, and summarizing to obtain a vector array steady focusing processor form which can be used for performing combined constraint on vector array focusing-oriented vector mismatch and a limited sampling effect simultaneously; (e) obtaining an optimal weight vector w; (f) obtaining optimized array output power; and (g) setting an appropriate step length, and repeating the step (c) to the step (f), searching for a complete plane, comparing, outputting a power spectrum, and determining the position of a noise source at a spectral peak position. The vector array steady focusing processing method is suitable for positioning an underwater noise source under a vector array testing condition.

The invention belongs to the technical field of ocean engineering and information technology fusion, and provides an underwater netting system damage detection method based on machine vision, which comprises mesh information identification and mesh anomaly detection. According to the net cage underwater netting damage detection method based on machine vision, the original video image of the netting is acquired through the ROV underwater robot, underwater noise is removed based on a traditional image processing technology, and then the netting image is simplified into a binary image. The area of each mesh is obtained through connected domain segmentation, a netting characteristic gradient curve is formed, a netting damage judgment formula is determined, the netting damage condition is judged according to a self-adaptive netting abnormal threshold value, the netting damage position in the original image is accurately returned, and the netting damage area is automatically framed. According to the method, automatic detection and analysis are carried out in the whole netting damage detection process, labor consumption in netting damage detection can be effectively reduced while nettingdetection efficiency is improved, and personal safety of workers is guaranteed.

The invention discloses a road river-crossing tunnel underwater vibration noise prediction method, and the method specifically comprises the following steps: firstly, obtaining traffic flow distribution of different working conditions according to the traffic flow statistics, and building a random vehicle model of each lane; then, establishing a fine three-dimensional tunnel structure-soil body finite element model, and simulating infinite domain boundary conditions of a soil layer; secondly, on the basis of a vehicle-tunnel-soil body coupling vibration model, carrying out vehicle-induced tunnel-soil body dynamic response analysis by considering influence of initial water pressure; then, establishing a water-soil fluid-solid coupling acoustic finite element model, and converting a vehicle-induced soil vibration response result to a frequency domain through Fourier transform and mapping the result to a fluid and soil coupling surface to serve as a vibration source of an acoustic model;and finally, solving underwater noise caused by tunnel vibration through an acoustic finite element-complete matching layer method. The method can be used for accurately predicting the underwater vibration noise of the road river-crossing tunnel, and a theoretical basis is provided for evaluating the noise influence of endangered underwater organisms.

The invention belongs to the technical field of control over vibration noise and particularly relates to a device for controlling underwater noise. The technical scheme of a device for suppressing flow-induced oscillation line-spectrum noise of an underwater cavity is that when a solenoid is electrified, a driving film does cyclical movement in a hydraulic cylinder under the action of an electromagnetic force, and converts inputted electric energy into kinetic energy for film movement; when the driving film expands, the pressure in the hydraulic cylinder is reduced, and external fluid is sucked into the cavity through a slit; and when the driving film shrinks, the pressure in the hydraulic cylinder is increased, and the fluid in the hydraulic cylinder is drained out of the cavity, thereby generating unsteady jet flow at the slit of a top cover. By utilization of mutual action of vortex generated by pulsating jet and a shear layer, jet flow and an open pore enter the shear layer for generating a strong effect and damaging self-sustained oscillation of the shear layer, thereby realizing the suppression on the flow-induced oscillation line-spectrum noise.

The invention relates to a wildlife protection technology, in particular to an acoustic induction protection device and method for Neophocaena asiaeorientalis asiaeorientalis in a construction water area. The acoustic induction protection method is implemented by an acoustic instrument. The acoustic induction protection method comprises the following steps: step 1, fixing the acoustic instrument in a specific safe water area outside a construction site, and controlling the placing depth to be half of the water depth; and step 2, using the acoustic instrument to generate acoustic signals so asto induce Neophocaena asiaeorientalis asiaeorientalis to move away from the construction water area and enter a safe water area where the acoustic instrument is located. The acoustic induction protection method for Neophocaena asiaeorientalis asiaeorientalis in the construction water area is developed by measuring whistles of Neophocaena asiaeorientalis asiaeorientalis, measuring the hearing ability of a wild small group Neophocaena asiaeorientalis asiaeorientalis, measuring the underwater background noise of a natural habitat of Neophocaena asiaeorientalis asiaeorientalis, and measuring the underwater noise of a construction project. The method can be used to effectively induce and protect Neophocaena asiaeorientalis asiaeorientalis in engineering construction water areas, and avoid accidental injury and accidental killing of Neophocaena asiaeorientalis asiaeorientalis by wading construction activities.

The invention relates to underwater acoustic signal processing, in particular to a method for estimating the frequency-band-division direction of an underwater broadband sound source across ice layers through a single detector. Corresponding requirements are put forward for the performance of the single detector, and windowing frequency division processing is carried out on underwater ice water sound source emission signals in three directions picked up by the single detector above an ice layer; correlation filtering is carried out on the received signals in the horizontal direction and the vertical direction; rotation analysis and searching the maximum radial energy are performed to obtain the orientation estimation of the sound source in the water under ice; 180-degree fuzziness correction is carried out on the horizontal azimuth angle corresponding to the maximum energy; the determined horizontal azimuth angles of all the frequency bands are marked on the same azimuth map to obtain all azimuth estimations within the frequency band range of 40Hz-1kHz; or marking is performed according to frequency bands to obtain azimuth estimation maps of different frequency bands. The problems that under the condition of sea ice coverage, a hydrophone array or a vector hydrophone is difficult to arrange, and flow noise in water and other underwater noise interfere with target sound source signals in water are solved. The method is easy to arrange, fast in response to an under-ice moving target sound source, small in interference, economical and practical.

The invention discloses an underwater image enhancement method combining a frequency domain and a spatial domain, and belongs to the field of underwater digital image processing. The method comprisesthe following steps: reading an underwater color image, and converting the underwater color image into a grayscale image; adaptively selecting the denoising degree of a frequency domain and the contrast enhancement degree of a spatial domain; converting the grayscale image into a frequency space by using Fourier transform; de-noising the image in the frequency space; inverse Fourier transform is performed on the denoised image, and the denoised image is converted to a spatial domain; segmenting the image of the spatial domain into a plurality of sub-image blocks, and calculating a gray probability density function of each sub-image block; redistributing the probability density function; and calculating the redistributed gray level of each pixel in the sub-image blocks to obtain a finally enhanced image. Compared with the prior art, the invention has the advantages that underwater noise interference can be well removed, image detail features are enriched, consumed time is short, and theinvention is suitable for underwater vision synchronous positioning and image preprocessing before mapping.

The invention relates to a strong-reflection underwater acoustic material and an application thereof, and belongs to the technical fields of underwater acoustic material design and underwater acousticpropagation control. The underwater acoustic material needs to meet the following conditions: the ratio of shear wave velocity to longitudinal wave velocity is less than 1 / 5, the ratio of the stiffness in the y principal axis direction and the stiffness in the x principal axis direction is greater than 10, and an angle [Theta] between a principal axis and an interface is not equal to 0 degree and90 degrees. The underwater acoustic material has the characteristics of low impedance and high stiffness, is effective for broadband and oblique incident acoustic waves at the same time and can meetunderwater acoustic strong reflection requirements in a deep high-pressure environment. In addition, the underwater acoustic material has excellent application prospects on the aspects of underwater noise prevention, low-frequency underwater acoustic high-directivity sound sources and acoustic pressure detection.

The invention discloses an offshore buoy with an underwater noise source passive positioning function. The offshore buoy with the underwater noise source passive positioning function comprises a buoybody; an anchor chain is connected to the bottom of the buoy body; a gravity anchor is connected to the bottom of the anchor chain and fixed to the seabed; the buoy body is further connected with a nylon rope which is provided with a noise source positioning array element device; and a camera device is arranged on the buoy body. A method for implementing underwater noise source positioning throughthe buoy comprises the following steps that 1, a self-adaptive threshold detection method is adopted for distinguishing an underwater noise source; 2, passive noise source positioning is conducted onthe distinguished underwater noise source through a multi-array-element mixed positioning method; and 3, the camera device is started, and the positioned noise source is photographed to obtain an evidence. The offshore buoy with the underwater noise source passive positioning function and the positioning method can be used for positioning the underwater noise source close to the buoy, can performevidence obtaining behaviors like photographing and are low in power consumption.

The invention discloses a test method for simulating influence of underwater noise vibration of ships and water transport engineering on fishes, and belongs to the technical field of ecological environment influence. Underwater noise vibration caused by ship noise and water transport engineering construction such as piling is simulated by a vibration sounding device and is transferred to a fish culture tank, and then the type and degree of influence on fishes by noise vibration are observed and analyzed. The main test method comprises the following steps: preparing a noise vibration source, testing a noise vibration propagation process, selecting a noise vibration influence receptor, and carrying out test analysis. The method can provide technical support for guiding shipbuilding and navigation and water transport engineering design and construction to adopt appropriate fish influence mitigation countermeasures and evaluating ecological environment influence.

The invention discloses an offshore wind turbine non-contact impeller rotating speed monitoring method based on underwater sound signals, and relates to the technical field of wind power. A hydrophoneis used for collecting offshore wind turbine operation period underwater noise close to a wind turbine in real time, a stochastic resonance method is used for extracting the line spectrum frequency of the operation period underwater noise, and then the frequency is used for inverting the impeller rotating speed of the wind turbine. And compared with a preset threshold value, when it is found thatthe rotating speed of the impeller is abnormal, the system gives an alarm and stops the running of the draught fan so as to guarantee the safety of the wind turbine. A monitoring instrument does notneed to be installed on a rotating shaft or other firmware of the wind turbine, the risks caused by abrasion, falling and the like due to the fact that an existing monitoring instrument needs to makedirect contact with the wind turbine for a long time are avoided, and the impeller rotating speed can be effectively monitored; the real-time changes of underwater noise in the offshore wind farm operation period can be tracked and monitored, key parameters are provided for the influence evaluation of marine environment noise, and the method has the advantages of being simple, low in cost, convenient to arrange and the like.

A zero-buoyancy optical cable watertight force bearing connector comprises a plug and a socket. The plug comprises a plug housing, a sealing tail sleeve, an O-shaped ring, a sealing assembly, a force bearing assembly and a plug butt-joint assembly. The socket comprises a socket housing, a locking nut, a sealing tail sleeve, a sealing assembly, a force bearing assembly and a socket butt-joint assembly. The plug butt-joint assembly comprises a baffle plate, an MPO optical fiber connector, a plug core and a plug retaining ring. The socket butt-joint assembly comprises an MPO optical fiber connector, an MPO optical fiber flange, a socket core and a socket retaining ring. When integral butt-joint between the plug and the socket is performed by means of a pair of MPO optical connectors through the MPO optical fiber flange, the plug housing is hermetically connected with the socket housing through the locking nut and the O-shaped ring. The zero-buoyancy optical cable watertight force bearing connector has advantages of high mechanical strength, high butt-joint coupling efficiency, high insertion loss consistency, low machining difficulty, low machining cost and long service life. The density of the zero-buoyancy optical cable watertight force bearing connector can approach the density of seawater. The zero-buoyancy optical cable watertight force bearing connector has advantages of greatly reducing resistance in towing and effectively reducing underwater noise of a system.

The invention discloses an operating fan underwater sound signal feature extraction method based on adaptive stochastic resonance, and relates to the field of offshore wind plant underwater noise. A self-adaptive stochastic resonance method is adopted, a time-frequency-amplitude comprehensive index established based on support vector regression serves as a fitness function, a balance optimizer serves as an optimization algorithm, system parameters are adjusted in a self-adaptive mode according to the ocean background noise intensity, and self-adaptive extraction of the characteristic frequency of the underwater sound signal in the operation period of the offshore wind turbine is achieved. The time-frequency-amplitude comprehensive index adopted by the method can reflect the information of the signal in the three aspects of time domain, frequency domain and amplitude domain, the problem of extracting the unknown frequency of the underwater sound signal in the operation period of the offshore wind turbine under the changing ocean background noise is solved, and the method has high accuracy. Besides, the balance optimizer adopted by the method can realize synchronous optimization of a plurality of system parameters, so that the operation time is greatly shortened, the efficiency of extracting the line spectrum frequency of the underwater sound signal in the operation period is improved, and the method has the characteristics of simplicity and easiness in implementation.

The invention discloses a river-crossing water supply pipeline tunnel underwater vibration noise prediction method which specifically comprises the following steps: firstly, establishing finite element models of a three-dimensional water supply pipeline tunnel structure and a soil body structure; then, establishing a fluid finite element model, and setting a boundary of a soil body structure; secondly, based on a fluid-solid coupling vibration model composed of a fluid finite element model and a structure finite element model, performing fluid-solid coupling vibration analysis by considering the influence of the initial fluid flow velocity, and obtaining the vibration response of the structure; then, establishing a fluid-solid coupling acoustic finite element model, and importing a fluid-induced soil body vibration response result into the acoustic model to serve as a boundary condition; and finally, solving noises caused by vibration of the underwater pipeline tunnel through an acoustic finite element and an automatic matching layer method. The method can be used for predicting the underwater vibration noise of the river-crossing water supply pipeline tunnel, the noise space attenuation rule is obtained, and a theoretical basis is provided for reducing the influence of the underwater noise.

The invention discloses a method and a system for improving underwater blue-green laser communication reliability, which belong to the field of underwater wireless communication, and are characterized in that data preprocessing and peak value judgment are combined with adaptive threshold value judgment, data preprocessing and denoising are carried out on pulses of a laser communication system, peak value judgment is carried out on denoised data, and the reliability of underwater blue-green laser communication is improved. And meanwhile, recovering the laser information in combination with a self-adaptive threshold judgment mode, and finally recovering the laser system transmitting end information. According to the invention, the defects in the prior art are overcome, a good inhibition effect on underwater noise interference of laser communication is achieved, information loss caused by underwater laser refraction and scattering is effectively avoided, and the reliability of underwater laser communication is improved.

The invention discloses an underwater target recognition method based on improved PSO-TSNE feature selection. The underwater target recognition method comprises the steps of performing underwater noise feature extraction on an underwater target radiation noise signal and normalizing data to obtain a standardized data set; performing dimension reduction processing on the data of the standardized data set by using T-SNE to obtain similarity between high-dimensional space data points, similarity between data points in a low-dimensional space, and an objective function and a step function for KL divergence optimization of the high-dimensional space data points and the low-dimensional space data points; obtaining an optimal KL value by using an improved PSO algorithm; and carrying out dimension reduction processing on the data of the standardized data set by using the minimum KL and the T-SNE again, and taking underwater target features to confirm a target. According to the method, the updated PSO is adopted to optimize the divergence in the T-SNE, so that the performance of the T-SNE is better.

The invention relates to technologies of wild animal protection, in particular to a device and method for acoustic repelling and protection of Neophocaena asiaeorientalis asiaeorientalis away from a construction water zone. The method comprises the following steps: (1) fixing acoustic repelling instruments in the water zone near a construction site at certain intervals, wherein the depth of the arranged positions is a half of the water depth; and (2) sending sound signals which can be changed randomly within a certain range automatically and continuously through the acoustic repelling instruments so as to drive the Neophocaena asiaeorientalis asiaeorientalis away from the construction water zone. According to the method, through measurement of echolocation signals of Neophocaena asiaeorientalis asiaeorientalis, measurement of the hearing ability of wild Neophocaena asiaeorientalis asiaeorientalis microcommunities, measurement of underwater background noise of natural habitats of Neophocaena asiaeorientalis asiaeorientalis and measurement of underwater noise of construction projects, the method for acoustic repelling and protection of Neophocaena asiaeorientalis asiaeorientalis awayfrom the construction water zone is obtained, and the method can be applied to effective repelling and protection of Neophocaena asiaeorientalis asiaeorientalis away from the engineering constructionwater zone, so that accidental injury and accidental killing of Neophocaena asiaeorientalis asiaeorientalis are avoided by engineering construction activities involving water.