30results about How to "Reduce noise amplitude" patented technology

The invention relates to a rotating speed filtering device and filtering method of a PMSM. The rotating speed filtering device of the PMSM comprises a position sensor, the PMSM, a rotating speed calculating module, a Kalman filtering module, a speed ring PI adjuster, a current sensor, a summation module, a coordinate transformation module, a first current ring PI adjuster, an SVPWM module, a second current ring PI adjuster and an inverter. The position sensor, the rotating speed calculating module and the speed ring PI adjuster form a speed ring. The coordinate transformation module and the current ring PI adjuster form a q-axis current ring. The coordinate transformation module and the current ring PI adjuster form a d-axis current ring, and the q-axis current ring and the d-axis current ring form a current ring. The filtering method based on the rotating speed filtering device of the PMSM can effectively filter the detecting noise of the rotor rotating speed of the PMSM, calculated loads are reduced, and the parameter dependence degree on the PMSM is lowered.

The invention discloses an interleaved parallel three-phase power factor correction (PFC) circuit. The circuit consists of two Vienna converters, wherein the Vienna converters have three-phase three-switch three-level PFC structures; three phase inputs of the first Vienna converter are connected with three phase inputs of the second Vienna converter respectively; three level outputs of the first Vienna converter are connected with three level outputs of the second Vienna converter respectively; the period starting time and the period ending time of three bidirectional switches of the first Vienna converter are the same; the period starting time and the period ending time of three bidirectional switches of the second Vienna converter are the same; and the period starting time and the period ending time of the three bidirectional switches of the first Vienna converter are half period earlier or later than the period starting time and the period ending time of the three bidirectional switches of the second Vienna converter.

The invention discloses a multi-scale ground microseism inverse time interference positioning method. The inverse time positioning and multi-scale variational mode decomposition are combined, the original microseism data is decomposed into multiple scale domains with different vibration characteristics through the multi-scale decomposition technology, the noise amplitude is gradually reduced alongthe increasing of the decomposition scale, the amplitude of the effective signal is gradually increased, the proportion of the background noise can be reduced, and then the precision of the seismic source positioning is improved; furthermore, the original microseism data is decomposition into multiple scale domains through the multi-scale variational mode decomposition, the characteristics of theeffective signals extracted from multiple scales are enhanced, the disadvantage of the sampling information caused by a sparse observation system can be remedied; the product of the effective scale inverse time interference positioning can improve the focusing and resolution of an inverse time interference positioning imaging ellipse, and then an imaging illusion is suppressed.

The invention discloses a non-pressure cured nitrile-butadiene rubber paint. The invention is characterized in that the non-pressure cured nitrile-butadiene rubber paint is prepared by compounding the following raw materials in parts by weight: 100 parts of nitrile-butadiene rubber, 30-60 parts of carbon black, 1-10 parts of vulcanizing agent and assistant, 30-100 parts of phenolic resin and 500-1100 parts of organic solvent. The non-pressure cured nitrile-butadiene rubber paint can be cured at a certain temperature without pressurization, and has the advantages of favorable surface hardness, favorable adhesiveness and favorable self antisticking property; the non-pressure cured nitrile-butadiene rubber paint can be used for preparing materials for shock absorption, sealing, sound insulation and the like in the fields of motor vehicles, refrigeration, petroleum, chemical engineering, compressors and the like, and can also be used for preparing a metal-rubber composite plate; and the prepared metal-rubber composite plate has favorable shock absorption property, noise reduction property, sealability, high temperature resistance, oil resistance and non-freezing solution resistance.

The invention relates to a method which can effectively eliminate narrowband noise and white noise in the cable local discharging signal. The method comprises steps of signal filtering pretreatment, wavelet threshold noise reduction and deconvolution. The narrowband noise and the white noise whose amplitude and frequency are irregularly changed can be well restrained.

The invention discloses a fiber optic hydrophone remote transmission array system based on compensation interference as well as a method. The system comprises a signal emission unit used for inputtinga pulse signal, a compensation interference unit which has unbalance arm difference and is used for converting the pulse signal into a pulse signal pair with delay and outputting the pulse signal pair with delay, an optical annular unit used for transmitting the pulse signal pair, a time division multiplexing array unit which is provided with a time division multiplexing array and used for splitting and delaying the pulse signal pair, merging all the delayed signals after a sensing signal is acquired and transmitting a time division multiplexing interference pulse signal provided with the sensing signal to a second port of the optical annular unit from an input output port and a signal receiving unit used for resolving the time division multiplexing interference pulse signal to obtain thesensing signal. The system disclosed by the invention can greatly enhance comprehensive performance of a large-scale fiber optic hydrophone remote transmission array, so that the large-scale fiber optic hydrophone remote transmission array can meet application requirements of related fields such as fiber optic hydrophone sealfloor shore-based fixed arrays.

The invention discloses a flange. The flange comprises a flange plate and a first connecting unit, wherein the flange plate comprises a flange hole formed in the center of a circle and at least one connecting groove, the first connecting unit is positioned in the connecting groove and is used for connecting a first element to one side surface of the flange plate, the first connecting unit comprises a bolt and a shock absorber which is positioned on the outer side of the bolt, the shock absorber is used for reducing axial displacement and axial vibration, and additionally, a noise transmission path can be cut off, so that the noise amplitude is reduced.

A regional filtering quality guided phase unwrapping method based on InSAL relates to a phase unwrapping technology, and is provided to solve the problem that the existing phase unwrapping method is poor in unwrapping result. The method comprises the following steps: determining a pixel of the highest quality in an overall interferometric phase image, and carrying out phase unwrapping; detecting four pixels adjacent to the pixel of the highest quality, unwrapping the pixels, and storing wrapped pixels adjacent to each unwrapped pixel in an adjacent column; selecting a pixel of the highest quality from the adjacent column, carrying out phase unwrapping, storing wrapped pixels adjacent to the pixel in the adjacent column, and updating the adjacent column; repeating the steps until the phases of all the pixels are unwrapped and a primary unwrapping map is obtained; determining error points of the primary unwrapping graph, getting a pixel error flag matrix, and getting a pixel error flag matrix expander graph; and carrying out regional filtering on the primary unwrapping graph. The method of the invention is suitable for phase unwrapping.

The invention relates to the field of a magnetic core fixing structure assembly of a Hall current sensor, in particular to a magnetic core air gap fixing structure assembly for a core passing type Hall current sensor. The magnetic core air gap fixing structure assembly is characterized in that a fixing hole or a positioning groove is formed in a single magnetic core with an air gap formed by lamination riveting and punching; a non-conductive metal sheet is riveted and punched or welded onto the upper top layer or the outermost upper and lower layers of the single magnetic core; the non-conductive metal sheet is welded onto the outer side surface or the top of the magnetic core air gap position by a single magnetic core with an air gap formed by winding; when the two single magnetic cores with the same dimension or the single magnetic cores with one or even air gaps and one fixing frame or framework is used, the two single magnetic cores with the air gaps are arranged on the upper and lower surfaces of the fixing frame or the framework; the even number of air gaps are in staggered arrangement or symmetrical distribution or uniformly divide the whole magnetic paths; the side surface of the fixing frame or the framework is provided with an insertion groove communicating the air gaps of the magnetic core; the conversion plate is inserted in the insertion groove; a Hall element arranged in the magnetic core air gap is directly connected with a printed circuit board or is connected with the printed circuit board through a conversion plate.

The invention discloses a diesel generator set adopting a disc type generator. The diesel generator set comprises a mounting base, a controller, a diesel generator, a water tank and a silencer, and further comprises the disc type generator, wherein the disc type generator is connected with the diesel generator; the disc type generator is electrically connected with the controller. The diesel generator set adopting the disc type generator has the advantages of small size, simple and compact structure, high power generation efficiency and small vibration noise.

The invention discloses a moisture flow measurement device based on an exempt-level radioactive source. The moisture flow measurement device is characterized in that the device comprises a section ofcylindrical pipeline (1) and a tapered throttling part (2) which is located in the section of cylindrical pipeline and arranged in the same axis as the section of cylindrical pipeline; the tapered throttling part (2) comprises a head conical section (22) and a tail conical section (23), both of which are arranged by sharing the same bottom surface; the head conical section (22) faces a moisture inlet of the cylindrical pipeline (1); an annular gap (3) is defined between the inner wall of the cylindrical pipeline (1) and a position with the largest diameter of the tapered throttling part (2) toallow moisture to pass through; the position with the largest diameter of the tapered throttling part (2) is equipped with exempt-level radioactive modules (4) which are arranged to enable emitted gamma rays to penetrate through the annular gap (3) along a radial direction; and therefore, the emitted gamma rays can reach gamma ray detectors (5) outside the cylindrical pipeline (1). The moisture flow measurement device based on the exempt-level radioactive source adopts the exempt-level radioactive source and is a major breakthrough in the field of multi-phase flow measurement equipment.

The invention discloses an optical fiber hydrophone array structure based on compensation interference. The structure comprises a signal input end which is used for inputting a pulse signal, a compensation interference assembly which has an unbalanced arm difference and is used for converting the pulse signal into a delayed pulse signal pair and outputting the delayed pulse signal pair, an opticalring assembly used for transmitting the pulse signal pair, a time division multiplexing array assembly which has a time division multiplexing array and is used for splitting and delaying the pulse signal pair, combining delay signals after sensing signals are obtained, and transmitting time division multiplexing interference pulse signals with the sensing signals to a second port of the optical ring assembly from an input / output port, and a signal output end used for outputting the time division multiplexing interference pulse signals with the sensing signals. According to the optical fiber hydrophone array structure, the comprehensive performance of a large-scale optical fiber hydrophone remote transmission array can be greatly improved, and the application requirements of related fieldssuch as optical fiber hydrophone seabed shore-based fixed arrays are met by the large-scale optical fiber hydrophone remote transmission array.

The invention discloses an impeller capable of increasing centrifugal pump noise tone quality and a design method thereof and belongs to the technical field of pumps. Normally, the blades of the impeller of a pump are distributed in an equal-distance manner and the exit edges of the blades are located on the same axial surface, so that intense dynamic and static interference exists between the blades and partition tongues, large noise energy is generated, the noise energy gathers under the signal blade passing frequency, the noise spectrum change shapely, and noise tone quality is poor. The impeller has the advantages that the distance between every two blades are optimized through a rotor automatic balance theory, a plurality of passing frequencies are generated, the noise energy gathered under the single blade passing frequency is reduced, corresponding noise pressure peak is reduced, the reduced noise energy is dispersed to other passing frequencies, stability of the noise spectrum is improved, the exit edges of the blades are allowed not to be located on the same axial plane, interference between the blades and partition tongues is weakened to a certain degree, the noise energy is reduced, overall noise amplitude is reduced, centrifugal pump noise tone quality is increased to a certain degree, and the impeller has certain popularization value.

The invention provides a combined air filter. The combined air filter comprises an upper shell, a lower shell, a filter element, a multi-hole plate and an adsorption layer. The upper shell and the lower shell are fixedly connected to form an airtight cavity, and the filter element is arranged in the airtight cavity. The multi-hole plate is arranged on the top of the upper shell so that a noise reduction cavity can be formed between the multi-hole plate and the top wall of the upper shell. The adsorption layer is arranged in the noise reduction cavity. By adopting the technical scheme, the problem that the space inside an engine cabin is limited, and consequently the noise reduction functional components are difficult to distribute is well solved, meanwhile, the hydrocarbon leakage problemunder the emission requirements in CN6 is also solved, two purposes are achieved at one stroke, and meanwhile, the combined air filter has the beneficial effects of being simple in structure, relatively low in process cost, good in manufacturability and durability, capable of saving energy, environment-friendly and the like. The invention further discloses a vehicle provided with the combined airfilter.

The invention provides a circuit board, electronic equipment and a manufacturing method of the circuit board. The method comprises the steps that the circuit board comprises a circuit board body and acapacitor which is arranged on the first end surface of the circuit board body, wherein the capacitor body of the capacitor is provided with a second end surface and a third end surface which are adjacent, and the second end surface faces and contacts the first end surface; the end electrode of the capacitor wraps the third end surface; and a first side formed by intersection of the second end surface and the third end surface is perpendicular to the short side of the first end surface. Therefore, the arrangement mode of the capacitor on the circuit board body can be standardized, and the first side formed by intersection of the second end surface and the third end surface is perpendicular to the short side of the first end surface so that the vibration bearing area of the circuit board can be effectively reduced and the amplitude of the noise generated by vibration of the capacitor can be reduced.

The invention provides a circuit board, electronic equipment and a manufacturing method of the circuit board. The method comprises the steps that the circuit board comprises a circuit board body and acapacitor which is arranged on the first end surface of the circuit board body, wherein the capacitor body of the capacitor is provided with a second end surface and a third end surface which are adjacent, and the second end surface faces and contacts the first end surface; the end electrode of the capacitor wraps the third end surface; and a first side formed by intersection of the second end surface and the third end surface is perpendicular to the short side of the first end surface. Therefore, the arrangement mode of the capacitor on the circuit board body can be standardized, and the first side formed by intersection of the second end surface and the third end surface is perpendicular to the short side of the first end surface so that the vibration bearing area of the circuit board can be effectively reduced and the amplitude of the noise generated by vibration of the capacitor can be reduced.

A regional filtering quality guided phase unwrapping method based on InSAL relates to a phase unwrapping technology, and is provided to solve the problem that the existing phase unwrapping method is poor in unwrapping result. The method comprises the following steps: determining a pixel of the highest quality in an overall interferometric phase image, and carrying out phase unwrapping; detecting four pixels adjacent to the pixel of the highest quality, unwrapping the pixels, and storing wrapped pixels adjacent to each unwrapped pixel in an adjacent column; selecting a pixel of the highest quality from the adjacent column, carrying out phase unwrapping, storing wrapped pixels adjacent to the pixel in the adjacent column, and updating the adjacent column; repeating the steps until the phases of all the pixels are unwrapped and a primary unwrapping map is obtained; determining error points of the primary unwrapping graph, getting a pixel error flag matrix, and getting a pixel error flag matrix expander graph; and carrying out regional filtering on the primary unwrapping graph. The method of the invention is suitable for phase unwrapping.

The invention provides a method and device for improving the switching power supply stability and a switching power supply. The method comprises the steps that positive output voltage and negative grounding voltage of the switching power supply are subjected to differential treatment, and first voltage is obtained; the alternating current component is removed for positive output voltage, and second voltage is obtained; the first voltage and the second voltage are subjected to comparison amplification, and differential voltage is obtained; according to the differential voltage, on-off time of the switching power supply is controlled in a negative feedback mode so as to stabilize the switching power supply. According to the method, by changing the feedback form of the switching power supply,an existing power supply voltage negative feedback form is turned into a differential negative feedback form, proper compensation is conducted according to the differential voltage, the amplitude ofpower supply noise is reduced, the effect of stabilizing the power supply voltage is achieved, and the technical problem that in the prior art, switching power supply fluctuation cannot be effectivelyreduced is solved.

A system and a method of noise mitigation for hybrid and electric aircraft are disclosed, the aircraft having a controllable pitch propeller or rotor(s) with a plurality of blades. The propeller or rotor(s) are driven by a drive system to provide thrust for the aircraft, and the blades of the propeller or rotor(s) are further movable about pivot axis to vary a pitch thereof. A controller on- boardthe aircraft is operable to cause rotation or movement of the blades of the propeller or rotor(s) about their pivot axis to alter and / or focus at least one aspect of the propeller generated noise toreduce or mitigate such noise while maintaining a substantially constant thrust, altitude, and / or air speed of the aircraft.