179 results about "Noise propagation" patented technology

A fluid handling duct such as a turbine engine inlet duct 20 includes an acoustic liner 32 comprising a face sheet 34 and a backwall 38 laterally spaced from the face sheet. The liner has a nonuniformly distributed acoustic impedance to direct sound waves incident on the backwall in a prescribed direction relative to the face sheet. The nonuniform impedance is spatially distributed to regulate the direction in which noise signals reflect from the backwall, thereby reducing noise propagation from the duct to the surrounding environment.

The invention discloses a manifold pre-integration-based visual inertial milemeter posture estimation method and device. After finishing the initialization of the visual inertial milemeter system, themethod comprises: visual inertial data alignment, visual optical flow position posture calculation, inertial pre-integration, visual and inertial joint optimization, window marginalization and aboveprocess repetition so that continuous estimation of camera postures is realized. Compared with the single visual milemeter system, the manifold pre-integration-based visual inertial milemeter system has a higher positioning precision, effectively utilizes inertial information in the milemeter system based on the manifold pre-integration algorithm, inhibits noise propagation of the system and reduces the influence of the inertial zero drift on the positioning accuracy of the milemeter.

A fluid handling duct such as a turbine engine inlet duct 20 includes an acoustic liner 32 comprising a face sheet 34 and a backwall 38 laterally spaced from the face sheet. The backwall is offset from the face sheet by a nonuniform depth D to direct sound waves incident on the backwall in a prescribed direction relative to the face sheet. In one embodiment of the invention, the backwall comprises a ramp. In another embodiment, the backwall comprises a series of steps offset from the face sheet by different depths. The nonuniform depth of the backwall may be tailored to regulate the direction in which noise signals reflect from the backwall, thereby reducing noise propagation from the duct to the surrounding environment.

The invention discloses a noise transmission route testing method for a railway vehicle. The noise transmission route testing method is a brand-new engineering testing scheme, and by means of the method, the outside near-field noises of the railway vehicle in high-speed operation can be accurately tested, the transmission route of the noises of the railway vehicle and the distribution of in-vehicle sound field can be recognized, and testing basis with strong pertinence and practical applicability can be provided for the vibration and noise reduction design and manufacture of the railway vehicle. The noise transmission route testing method for the railway vehicle includes: arranging a plurality of mutually different sections according to the noise sources and the characteristics of a vehicle body, wherein each section is an independent two-dimensional sound field; choosing to test one or several items of noises outside the vehicle, vehicle body vibration, vibration of an inner decoration board, near-field noises in the vehicle and standard point noises in the vehicle on each section; and dividing each section of the vehicle body into a vehicle top, a lateral top, a lateral wall, a water blocking board and a floor when testing the standard point noises Lp in the vehicle.

Robust feedforward active noise cancellation is provided which can overcome or substantially alleviate problems associated with the diverse and dynamic nature of the surrounding acoustic environment. A multi-faceted analysis is performed to determine the direction (or directions) of propagation of noise in the surrounding acoustic environment. The direction of propagation is then utilized to determine direction-dependent characteristics of the acoustic path between a reference position where the noise is captured and a desired position where the noise is to be cancelled. These characteristics are used to form a feedforward signal adapted to cancel the noise at the desired position. By forming the feedforward signal based on direction-dependent characteristics of the acoustic path, the techniques described herein can achieve optimal noise cancellation at the desired location, regardless of the direction of propagation of the noise.

A fast accurate multi-channel frequency dependent scheme for analyzing noise in a signal processing system is described herein. Noise is decomposed within each channel into frequency bands and sub-band noise is propagated. To avoid the computational complexity of a convolution, traditional methods either assume the noise to be white, at any point in the signal processing pipeline, or they just ignore spatial operations. By assuming the noise to be white within each frequency band, it is possible to propagate any type of noise (white, colored, Gaussian, non-Gaussian and others) across a spatial transformation in a very fast and accurate manner. To demonstrate the efficacy of this technique, noise propagation is considered across various spatial operations in an image processing pipeline. Furthermore, the computational complexity is a very small fraction of the computational cost of propagating an image through a signal processing system.

A method is provided to evaluate substrate noise propagation in an integrated circuit design, the method comprising: providing a tile definition that specifies an electrical model associated with instances of the tile; mapping a plurality of respective tile instances to respective locations of the substrate; obtaining respective waveforms indicative of digital switching induced power grid fluctuations associated with the respective identified contacts; and associating a voltage with a selected tile instance of the tile grid that is indicative of substrate noise injection due to waveforms associated with contacts encompassed by the selected tile instance.

A ductless dryer includes a main body, a drum rotatably installed at the main body, a heat exchanger for removing moisture from air exhausted from the drum, a circulation duct to flow the air exhausted from the drum into the heat exchanger, an exhaust duct to flow the air exhausted from the heat exchanger outside the dryer; and a noise reduction portion to attenuate noise propagation through the exhaust duct. As the ductless dryer is provided with the noise reduction portion, the noise propagation through the exhaust duct exposed into the room and the noise of the entire ductless dryer can be attenuated at the same time, whereby a quieter room environment can be provided.

An apparatus for electromagnetic interference shielding is described herein. The apparatus includes an electromagnetic bandgap (EBG) structure. The EBG structure is attached to a surface of the apparatus such that noise propagation is mitigated. The apparatus may be a chassis of an electronic device, and the EBG structure may be attached to one surface of the chassis. Further, the apparatus may be a heat sink, and the EBG structure can be attached to one surface of the heat sink.

A printed circuit board analyzing system for analyzing the whole circuit of a multilayer printed circuit board to perform circuit analysis of noise propagation in the printed circuit board having structure in which the shapes of stacked conductor planes are different or planes are provided side by side in the same layer by quickly providing an adjacent interference part equivalent circuit model representing noise interference parts causing interference between adjacent opposed planes and by coupling the plane pairs to the adjacent interference part equivalent circuit.

According to an exemplary embodiment of the invention, a combined habitation module for the crew of an aircraft is provided, which habitation module comprises two monument units that are separated from each other by a gap such that acoustic decoupling of the two monument units from each other is provided. In this way noise propagation within the habitation module may be prevented to a large extent.

The invention discloses an indoor robot motion estimation method based on deep learning and visual inertia fusion. A deep learning method is used to carry out feature extraction on visual data througha designed GCN network. Visual inertial navigation information is fused, and a robust SLAM system is constructed by the method. The robustness of the system can be greatly improved. Rapid deploymentcan also be carried out on embedded equipment with limited computing power. Through performing Pre-integration processing on inertia information, inter-frame constraints of visual information are formed. A joint optimizer is adopted to perform fusion optimization on the visual inertia output data. Compared with a single visual odometer system, the visual inertial odometer system based on pre-integration has higher positioning precision, inertial information is effectively used in the odometer system based on a pre-integration algorithm, noise propagation of the system is inhibited, and the influence of inertial null drift on the odometer positioning precision is reduced.

The invention discloses a method used for predicting a ground sound field of a helicopter rotor, and is used for simulating influence on the ground sound field by rotor noise in a helicopter flight process. The method comprises the following steps: carrying our rotor aerodynamic load calculation, designing and calculating a second-level acoustic radiation ball, carrying out ground observation region point dispersion, establishing a noise propagation model, and calculating the ground sound field. The method disclosed by the invention can greatly shorten time for calculating the influence on the ground by the rotor noise on the basis of a traditional direct calculation method. Since the method establishes the noise propagation model which considers the influence on noise propagation characteristics by environmental factors including atmosphere, ground and the like, compared with the traditional method, the method disclosed by the invention can obviously improve result prediction accuracy.

In a magnetic resonance tomography MRT apparatus noise suppression by strong damping of mechanical vibrations, in particular gradient coils and magnet vessels, is achieved through the use of composite materials that have electrostrictive properties. The invention generally relates to a nuclear spin tomography method (thesaurus: magnetic resonance tomography method MRT) for the examination for patient in iatrology. The invention especially relates to a nuclear spin tomography apparatus, wherein, many kinds of vibrations of the equipment parts which cause bad effect to the whole system can be depressed, and noise transmission routes can also be reduced. The nuclear magnetic resonance tomography apparatus has a base magnet (1) covered by a magnetic housing (12) that surround an inner space (21) in which the gradient coil system (2) is arranged. The apparatus includes damping elements (14), arranged at an inner wall of the magnetic housing (12) that surround the inner space (21), for absorption of acoustic vibrations, that are produced during switching of the gradient coil system (2). The damping elements contain material with electrostrictive properties.

The invention discloses a dynamic traffic flow based forecast method of noise in the peripheral zone of a long straight road. According to the method, a microcosmic moving trajectory of a vehicle in a road section is defined accurately, a vehicle source emission model is established, a noise transmission model is established simultaneously, and a complete set of noise forecasting method is obtained. The forecast method comprises steps as follows: (1), dynamic traffic flow simulation vehicle models at a forecast location are classified, and a dynamic traffic flow simulation model is established; and (2), reference radiation sound levels of different vehicle models are determined, meanwhile, traffic composition, range attenuation and noise barrier insertion loss are considered to calculate forecast sound level of the noise, and the forecast sound level is amended with consideration of surface roughness, the slope and the roadside ground type. According to the forecast method, limitation of the conventional noise forecast method is broken through on the basis that correlation research ideas of other subjects are absorbed sufficiently, and the sound level of the noise in a sensitive area can be forecast accurately.

A surface mount type capacitor comprises an anode section having an anode portion and first and second leads, cathode section including a cathode portion, first and second anode terminals, a cathode terminal, and a metal member. The capacitor further has an additional terminal electrically connected to the metal member and to be grounded to an object to which the capacitor is to be mounted.

The invention discloses a transformer substation worker workplace noise analysis method, which comprises the following steps of 1) basic data collection; 2) physical model building; 3) work point noise value calculation; 4) exposure limit judgment; and 5) work point occupational sanitation evaluation. The method has the advantages that the influence on the noise attenuation caused by the geometric divergence of the noise propagation, and atmosphere, ground, buildings, green belts and the like in the propagation path can be accurately considered, so the noise intensity of any work points in a transformer and the peripheral space of the transformer can be accurately predicated, references are provided for the transformer substation worker workplace noise sanitation evaluation, and the monitoring and the evaluation of the transformer substation noise occupational sanitation can be effectively assisted. Meanwhile, the invention also provides a transformer substation worker workplace noise analysis system.

The invention discloses a high-speed railway sound barrier insertion loss prediction method of a five-sound-source mode. The method comprises the following steps of equivalently simplifying a high-speed railway noise source into a wheel-rail area noise source, a train body lower part noise source, a train body upper part noise source, a current collection system noise source and a bridge structure noise source according to the composition, position, frequency characteristics and attenuation law of the high speed railway noise source, and respectively calculating the insertion loss of a wing plate for the five sound sources by virtue of a single-sound-source mode; spreading the noise of a wheel-rail area, a train body lower part, a train body upper part, a current collection system and a bridge structure to be superimposed with noise on a sensitive point after a sound barrier is installed, obtaining a main noise grade after the sound barrier is installed, subtracting the main noise grade from the noise grade before the sound barrier is installed, introducing an insertion loss correction item of the bridge wing plate, and obtaining an insertion loss prediction value by adopting the five-sound-source calculation method. By adopting the method, the weaknesses in the traditional sound barrier insertion loss prediction method can be overcome. The high-speed railway sound barrier insertion loss prediction method is applied to the high-speed railway sound barrier engineering design and the ambient noise influence valuation and has the advantages of accurate prediction value and high engineering practicability.

An active noise cancellation system (26) for controlling engine noise propagation through a vehicle induction system (32) is customizable to achieve a desired engine noise profile. A controller (34) of the active noise cancellation system drives a speaker (36) to generate a noise cancellation sound in a manner consistent with an individual's indicated preference for a specific type of available engine noise profile. By customizing how the speaker is driven, the system customizes the resulting engine noise heard in the passenger compartment. In one example, the system is customizable using a hand held communication device (24) such as a cell phone, a personal digital assistant or a so-called palm top computer. In another example, a resident communication bus on the vehicle is accessed through a user communication interface (28) supported on the vehicle.

The invention discloses a time-frequency domain hybrid adaptive active noise control algorithm. According to the algorithm, an entire control filter is divided into two blocks according to time delay characteristic of noise propagation; one of the two blocks is used for finishing filtering in time domain to guarantee no time delay, and frequency-domain filtering is adopted by the other one of the two blocks; the updating of both the filters of data of the two blocks is finished in the frequency domain; and thus, the algorithm guarantees that zero time delay control of a noise signal is firstly achieved and the amount of calculation of the entire system is reduced by utilizing a multi-time delay frequency domain algorithm, thereby integrally improving the applicability and the performance of the multi-time delay frequency domain algorithm. The time-frequency domain hybrid adaptive active noise control algorithm has the obvious advantage of breaking through the time delay limit of the multi-time delay frequency domain adaptive algorithm and can be used at places without time delay requirements.

The invention discloses a fully-closed noise reduction structure of a refrigeration compressor. The refrigeration compressor is provided with an exhaust valve. The exhaust valve consists of a valve plate (1), an exhaust valve block (2) and an exhaust valve block limiting plate, the exhaust valve block limiting plate is a cold-rolled carbon steel limiting plate (3), and a damping material layer is arranged on the surface, facing to the exhaust valve block (2), of the cold-rolled carbon steel limiting plate (3). In the technical scheme, an exhaust valve block impact zone is provided with a damping valve seat material or buffering valve block, sound energy generated by mechanical noise excited by the exhaust valve block can be absorbed and consumed by the damping valve seat material or buffering valve block, impedance matching between the exhaust valve block and the valve seat material is destroyed, noise excited by a noise source is lowered, a noise propagation route is cut off, and knocking mechanical noise of the compressor is lowered.

A SiC semiconductor device includes: a SiC substrate made of intrinsic SiC having semi-insulating property; first and second conductive type SiC layers disposed in the substrate; an insulation separation layer made of intrinsic SiC for isolating the first conductive type SiC layer from the second conductive type SiC layer; first and second conductive type channel JFETs disposed in the first and second conductive type SiC layers, respectively. The first and second conductive type channel JFETs provide a complementary junction field effect transistor. Since an electric element is formed on a flat surface, a manufacturing method is simplified. Further, noise propagation at high frequency and current leakage at high temperature are restricted.

Systems and methods of detecting arcing in a DC power system that can provide improved noise propagation immunity. The system includes at least two current sensors for monitoring at least two current outputs, respectively. The current sensors have reverse polarities, and are configured and arranged in parallel to provide a combined current output signal. The current sensors monitor the respective current outputs, which are provided for monitoring by the current sensors over at least two adjacent conductors. If arcing occurs at a location on a first conductor, then arcing (adjacent conductor crosstalk), having an arc current signature like that of the arcing on the first conductor, can occur at a location on the other adjacent conductor. The system can effectively cancel out such adjacent conductor crosstalk within a photovoltaic (PV) system, thereby improving the capability of an arc fault detection device for detecting arcing at the PV string level.

The invention discloses pipeline system flow noise suppression device and method broadening acoustic band gaps. The device comprises a pipeline system, first mufflers and second mufflers, wherein the first mufflers and the second mufflers are respectively arranged in the pipeline system in cycles, and the muffling frequency range of the first mufflers is smaller than that of the second mufflers. According to the pipeline system flow noise suppression device and method broadening the acoustic band gaps, the in-pipe flow noise transmission is suppressed by the adoption of Prague band gaps and local resonance band gaps generated by a cellular photonic crystal pipeline with the composition of the first mufflers and the second mufflers; certain offsets are taken during the arrangement of the two kinds of mufflers, so that the Prague band gaps can be further broadened, and the suppression of low frequency broadband flow noise in the pipeline is achieved.

A noise attenuation system is disclosed for use in a structure having a recessed fixture mounted therein or other unit which creates a hole in the structure in which it is secured, such as a ceiling. The noise attenuation system is constructed to permit the absorption of noise emitted into the structure from the mechanism. The noise attenuation includes a noise absorbing muffler positioned within the structure in an area substantially surrounding the mechanism. The noise absorbing layer includes an outer barrier layer that limits the passage of sound waves emitted from the mechanism therethrough. The noise absorbing muffler further includes a noise absorbing layer positioned adjacent the outer barrier layer. The noise absorbing layer absorbs a predetermined amount of sounds waves emitted from the recessed fixture. Additionally, an optional noise absorbing layer, or equivalent decoupling material can be included to decouple the barrier from the structure for low frequency noises.

The invention discloses a noise suppression method for processing in different frequency bands, which is used for suppressing noise in call sound and comprises the following steps of: converting the signal type of acquired sound data into a frequency domain signal from a time domain signal; dividing the frequency domain signal into a low-frequency signal and a medium-high frequency signal, calculating a low-frequency noise power spectrum estimated value according to the amplitude of the low-frequency signal, and calculating a medium-high frequency noise power spectrum estimated value accordingto the amplitude of the medium-high frequency signal; calculating according to the low-frequency noise power spectrum estimated value, the medium-high-frequency noise power spectrum estimated value and the frequency domain signal to obtain a gained frequency domain signal; and converting the gained frequency domain signal into a gained time domain signal. The invention also discloses a noise suppression system for processing in different frequency bands. According to the invention, the noise propagation is inhibited, the voice call quality is improved, and the noise in the call is effectivelyinhibited.

The invention provides a noise map updating method combining speed and noise monitoring data, which comprises the following steps of: classifying roads in a static noise map according to road grades,and clustering each class according to road speed; calculating the variation of a noise value of each road caused by speed change by acquiring speed data of the road at an updating moment, and calculating the variation of the noise value of the monitored road caused by density change by combining noise monitoring data of each road; finally, calculating the variation of the noise value of each roadcaused by the density change according to the calculated variation of the noise value of the monitored road caused by the density change, calculating the variation of the noise value of each road relative to the static noise map moment under the current traffic condition according to the results of the two parts, and calculating the noise value of each road relative to the static noise map momentunder the current traffic condition; and finally, updating the whole noise map according to the updating result of the noise source and the noise propagation model.