195results about How to "Play the role of noise reduction" patented technology

The invention relates to direction of arrival estimation for source signals, provides an algorithm for DOA (Direction of Arrival) estimation under a mutual coupling condition of unknown array elements. Under the premise of a sparse reconstruction theory, the algorithm makes full use of all information received by an array, and the angle estimation precision can be improved under strong mutual coupling of the array. The technical scheme adopted by the invention is that the method for sparse DOA estimation under mutual coupling of array elements comprises the steps of 1, calculating a covariance matrix R for a received signal X^(t); 2, performing singular value decomposition on the covariance matrix R; 3, calculating a signal subspace RS for receiving data according to a signal unitary space; 4, building a sparse signal complete dictionary AJ according to parameterization J of a steering vector; 5, building a convex programming function for sparse signal reconstruction according to a norm l1; 6, solving the convex programming function and performing spectrum peak search; and 7, further improving the estimation precision by using a principle of grid refinement. The method is mainly applied to direction of arrival estimation for signals.

The invention relates to a multistage crusher for mining use. The multistage crusher comprises a shell, a feed hopper, an outlet hopper and a rack. The feed hopper is arranged at the upper end of the shell. The outlet hopper and the rack are disposed at the lower end of the shell. A first coarse crushing roll and a second coarse crushing roll which are parallel to each other are arranged inside the shell. Several coarse crushing teeth which are engaged with each other are arranged on the periphery of the first and second coarse crushing rolls. A first fine crushing roll and a second fine crushing roll which are parallel to each other are arranged below the first coarse crushing roll and the second coarse crushing roll inside the shell. Several fine crushing teeth which are engaged with each other are arranged on the periphery of the first fine crushing roll and the second crushing roll. In addition, teeth number of the fine crushing teeth is greater than teeth number of the coarse crushing teeth. A partition plate is arranged inside the shell, and a ventilation channel is formed between the partition plate and a sidewall of the shell. The outside of the shell is provided with an exhaust fan which matches the ventilation channel. Besides, an output end of the exhaust fan is connected to a dedusting box through a pipeline.

The invention relates to the field of dishwashers, in particular to a dishwasher condensation drying system, a condensation drying method and a dishwasher. The dishwasher has an inner container enclosing a washing chamber. The condensation drying system comprises an air exhaust device and a collection chamber used for collecting air in the washing chamber. The collection chamber is provided with an air outlet, the air exhaust device comprises a housing and a fan arranged in the housing, one end of the shell is communicated with atmospheric air and the other end is communicated with a condensation chamber. An air outlet of the collection chamber is communicated with the housing, and the fan is arranged at one end of the housing distant from the condensation chamber and the air outlet. An openable air separator is arranged in the air outlet. When the air separator is opened, the collection chamber is communicated with the housing, and the fan can guide external air and humid air in the washing chamber into the condensation chamber. Cold drying air outside and hot humid air can enter the condensation chamber to significantly improve drying and condensation efficiency. In addition, humid air has no need to pass the fan and thereby has no damage to the electric control system of the fan.

The invention provides a self-cleaning negative pressure blower which comprises a first cylindrical shell, a first cleaning assembly, a first filter screen, a suction assembly, a second filter screen, a second cleaning assembly and a dirt collecting assembly, wherein a first end of the first cylindrical shell along the axial direction is provided with an indoor port, and a second end is an outdoor port; the first cleaning assembly, first filter screen, suction assembly, second filter screen and second cleaning assembly are respectively arranged in the cavity of the first cylindrical shell, and are sequentially arranged along the first cylindrical shell from the first end to the second end; the dirt collecting assembly comprises a drainage pipe and a collecting bag; a first end of the drainage pipe is provided with a first branch pipe and a second branch pipe; the first branch pipe and second branch pipe are respectively communicated with the inner cavity of the first cylindrical shell; and a second end of the drainage pipe is connected with the collecting bag. The self-cleaning negative pressure blower is simple and practical, can implement self-cleaning, and saves time and labor.

The invention provides a device with a feeding function. The device includes a feed cylinder, a rotation bin, and an ejection cylinder; the feed cylinder is provided with a discharge opening, and delivery feed is placed in the feed cylinder; the rotation bin is connected with the discharge opening, a bin opening is formed in the rotation bin and rotates along with the rotation bin, so that the rotation bin has a feed receiving state and a feed falling state, wherein in the feed receiving state, the rotation bin receives the delivery feed falling from the discharge opening, and in the feed falling state, a certain amount of the delivery feed in the rotation bin is released; a receiving opening communicated with the rotation bin is shaped and formed in the ejection cylinder, and the ejection cylinder is used for ejecting the delivery feed which falls into the ejection cylinder to the outer side of the ejection cylinder. By the adoption of the device with the feeding function, a user can remotely send a control command to achieve the pet feeding function and control the feeding amount for pets, and the safety and rationality of per feeding are ensured.

The invention discloses a fractal sound absorbing superstructure comprising a regular hexagonal air region 1 and six equilateral triangular structures (2, 3, 4, 5, 6 and 7). Each equilateral triangle structure has a zigzag fractal acoustic wave channel comprising a first-level zigzag fractal acoustic channel 10, a second-level zigzag fractal acoustic wave channel 12 deriving from the first-level zigzag fractal acoustic wave channel 10, and a third-level zigzag fractal acoustic wave channel 14 deriving from the second-level zigzag fractal acoustic wave channel 12. Both ends of the zigzag fractal acoustic wave channel communicate with an external sound field 8 and the internal hexagonal air region 1, respectively. The fractal sound absorbing superstructure of the invention has two complete band gaps at low frequency, has a unipolar resonance and bipolar resonance phenomenon at the low frequency. The complete band gap, the unipolar resonance and the bipolar resonance make acoustic energy gather in the fractal sound absorbing superstructure and stop the acoustic wave from spreading forwards.

The invention discloses a polishing device for an aluminium alloy door and window support notch, and relates to the technical field of aluminium profile machining. The polishing device comprises a working table, a clamping plate is fixedly connected to the middle portion of the upper surface of the working table, an object containing hole is formed in the top of the side face of the clamping plate, an elastic mat is fixedly connected to the lower surface of the inner wall of the object containing hole, and the upper surface of the elastic mat and the lower surface of an aluminium plate are inlap joint. According to the polishing device for the aluminium alloy door and window support notch, when polishing discs are in contact with the notch of the aluminium plate, polishing work can be done on the notch, a large quantity of flying chippings can be generated in the polishing process of the polishing discs, the flying chippings are limited into a protection cover under the effect of theprotection cover and then flows out through a drain outlet, the condition that the flying chippings hurt people can be effectively reduced, the two polishing discs can polish the two side faces of thealuminium plate at the same time, and therefore the working efficiency of a worker can be improved.

The invention discloses a heterogeneous federated learning mine electromagnetic radiation intensity trend tracking method based on an SVD algorithm, and the method comprises: firstly proposing a heterogeneous model federated learning algorithm for the problem of data imbalance in a federated learning client, and setting a heterogeneous central model in a server for the client to select, so as to improve the precision of a local model; aiming at the problem of uploading communication cost of local model parameters, providing an efficient communication algorithm that an SVD algorithm is firstlyused for decomposing a parameter matrix to obtain a corresponding singular value matrix, and then the singular value matrix is uploaded to a central server for aggregation updating; and finally, usingthe updated local model by each client to extract local data features, and using the features and real data values by each client to train the ESN and then to execute trend tracking. According to theinvention, trend tracking of electromagnetic radiation intensity acquired by multiple sensors can be realized on the premise of protecting data privacy, the trend tracking precision of each client can be improved, and the communication cost required by a framework is reduced.

The invention discloses an axial flow fan ternary impeller with a vein-shaped structure and a nonuniform empennage. The axial flow fan ternary impeller comprises a hub, and a connecting piece for a shaft sleeve fixed on the hub. The axial flow fan ternary impeller further comprises twisted blades and splitter blades fixedly connected to the hub; the twisted blades include suction surfaces and pressure surfaces; wing-shaped grooves are formed in the tops of the twisted blades; vein-shaped grooves are formed in the upper half parts of the pressure surfaces of the twisted blades; the wing-shaped grooves are communicated with the vein-shaped grooves through exhaust ports; winglet projections and dense winglets are arranged at the tail parts of the suction furnaces of the twisted blades; the dense winglets are arranged on two sides of the winglet projections; parabola small holes are formed in the twisted blades; the splitter blades are arranged between two adjacent twisted blades; and the heights of the splitter blades are smaller than the heights of the twisted blades by one half.

The invention relates to the field of medical instruments, and specifically relates to an air channel control device of breathing machine; the air channel control device of breathing machine comprises a first input end, a first filter, a first noise reducer, a turbine, a changeover valve, a first flux sensor, a second noise reducer, a first check valve and a first output end which are sequentially connected; the air channel control device of breathing machine further comprises a bypass pipe, an exhalation valve and a three-way electromagnetic valve; one end of the bypass pipe is connected with the changeover valve; the other end of the bypass pipe is connected with the first filter; one ends of the changeover valve and the exhalation valve are connected with the first check valve and the first output end; the other end of the exhalation valve is connected with an air inlet end of the three-way electromagnetic valve; an air outlet end of the three-way electromagnetic valve is connected with the first flux sensor and the second noise reducer. The air channel control device of breathing machine takes effect of reducing the noise by the noise reducers in front of and behind the turbine, makes the air flow more stable, makes the control easy and convenient, increases the precision of the system, ensures the comfort of the patient, and provides convenience for user experience.

The invention discloses a sound absorption superstructure. The sound absorption superstructure comprises a regular hexagon air domain 5, six regular hexagon single cells (6, 7, 8, 9, 10 and 11) at the first layer of the periphery of the regular hexagon air domain 5, and twelve incomplete regular hexagon single cells (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 and 23) at the second layer of the periphery of the regular hexagon air domain 5. All single-cell Helmholtz resonant cavities communicate with an external sound field 4 through resonant short tubes. According to the invention, the sound absorption superstructure has single-pole resonance and bipolar resonance phenomena at a low frequency, single-pole resonance can generate a negative dynamic volume modulus, yet bipolar resonance can generate negative dynamic quality density. Due to the negative dynamic volume modulus and the negative dynamic quality density, sound energy is aggregated in the sound absorption superstructure, and thus sound waves are prevented from continuously spreading forward. Therefore, the sound absorption superstructure forms a wide band gap between a single-pole resonance frequency and a bipolar resonance frequency and prevents propagation of the sound waves through a resonant sound absorption mode.

The invention relates to a blade front edge misplaced impeller. First, suppose the number of the blades of the fan impeller to be even, and then mount the blades equidistantly around the circumference on the hub of the axial-flow fan or on the wheel disk of the centrifugal fan. The front edges of odd and even series blades are misplaced. If the distance between the front edge of the two series blades satisfies the condition of making the phase of two sound waves reverse or differ by half a wavelength, two sound waves with the same frequency and amplitude and reversal phases are constructed.

The invention discloses an anhydrous coolant and a preparation method thereof. The anhydrous coolant comprises raw materials in parts by weight as follows: 1,000 parts of propylene glycol, 2.4-2.6 parts of an acidic preservative, 1.5-1.7 parts of borax, 1.4-1.6 parts of sodium nitrite, 1.4-1.6 parts of triethanolamine, 0.2-0.4 parts of benzotriazole, 0.05-0.15 parts of a defoaming agent, 5-7 parts of a bittering agent and 0.009-0.011 parts of a pigment. All components of the anhydrous coolant supplement one another and cooperate with one another to have the synergistic effect, the anhydrous coolant has the excellent performance and the wide adaptability, can be perfectly compatible with a hydrous coolant left during replacement of the coolant, enables an engine cooling system to work in a non-pressure or micro-pressure environment, can play a noise reduction role in an engine and cannot age and damage rubber pipelines in advance, so that usage and maintenance costs are reduced, and the service life of the engine is greatly prolonged. Besides, no water exists, so that propylene glycol cannot be acidic at the high temperature, the service life can be prolonged, frequent replacement is not required, the more environment-friendly effect is realized, and the long-term comprehensive cost performance is particularly high.

The invention discloses a computer case with a shock-proof function. The computer case comprises a rack, wherein side plates are fixedly arranged on the side surfaces of the rack; the upper part of the inner side of each side plate is fixedly provided with a power supply shock-proof pad; a cooling hole plate is arranged below each power supply shock-proof pad; the lower part of the rack is movably provided with a U-shaped sleeve; the outer surface of the bottom of the rack and the inner surface of the bottom of the U-shaped sleeve are connected by at least one group of parallel elastic components and damping components; the top cover of the rack is also provided with a dust-proof net; a cooling fan is arranged below the dust-proof net in the rack. The computer case with the shock-proof function has the advantages of simple structure and good shock-proof function. The junction of the outer surface of the bottom of the rack and the inner surface of the bottom of the U-shaped sleeve is provided with at least one group of parallel elastic components and damping components, so inner electronic components are effectively prevented from damage when the case shocks, and an effect on dust prevention can be effectively achieved in a manner that the top cover and the bottom plate of the rack are respectively provided with the dust-proof net.

The invention relates to a soya-bean milk production method with efficient pulverization and noise reduction. The method at least comprises the following steps: (a) a step of pre-heating and soaking, in which, water and materials are added in a heating cup of a heating apparatus, a pre-set temperature no less than 70 DEG C is achieved by heating at a heating rate in a range of 3 DEG C per minute to 10 DEG C per minute, and the next step is carried out; (b) a step of pulverization, in which, water and materials in the cup are pulverized into a thick liquid through rotation of a pulverization blade driven by an electric motor, and the next step is carried out; and (c) a step of cooking, in which, the thick liquid in the cup of the heating apparatus is heated until the thick liquid is fully cooked. Through comparison with the prior art, according to the technical scheme, the method enables the water absorption and expansion rate between epidermis and cotyledon of soya-beans to be preferably uniform, so that the soya-beans can fully absorb water and swell. The method has improved pulverization efficiency and has the function of noise reduction.

The invention relates to a Hall device-based motor speed measurement method and device, a readable storage medium and electric equipment, and the method comprises the steps: carrying out the AD sampling of an output signal of a Hall device in real time, so as to obtain a sampling signal, and enabling the Hall device to be used for detecting the rotating speed of a motor; converting the acquired sampling signal into a pulse signal; respectively calculating the period of each pulse signal to form a period sequence; and determining the rotating speed of the motor according to the periodic sequence. By means of the technical scheme, the noise reduction effect can be achieved, and the response time is shorter.

The invention relates to the technical field of a gear, in particular to an electric block protection gear. The electric block protection gear comprises a gear main body, wherein an installing groove is formed in the center of the gear main body, the left plane and the right plane of the gear main body are provided with a protection plate, a circle of spiral fixing groove is formed in the outer part of the installing groove, internal screw threads are arranged on the periphery of an inner ring of the spiral fixing groove, a convex head is arranged at the inner side of the protection plate, external screw threads corresponding to the internal screw threads are arranged inside the convex head, the protection plate is made of stainless steel, the thickness of the stainless steel is 0.2mm, a filling layer is arranged inside the protection plate, and materials inside the filling layer are foam. The electric block protection gear has the advantages that accidental injury to workers can be prevented through the additional arrangement of the protection plate, and a guide effect is also achieved, so the deviation cannot be generated during the gear operation, and foam fillings achieve the effects of noise reduction and sound elimination.

The present application discloses an electronic assembly and glasses. The electronic assembly comprises an accommodating body, a cover body, a first circuit board and a second circuit board; an open cavity is defined in the accommodating body; the opening of the cavity is covered with the cover body; the first circuit board is disposed in the cavity in a manner that the first circuit board is parallel to the opening plane of the opening; the surface of one side of the first circuit board is provided with a first microphone component, wherein the one side of the first circuit board faces the cover body; the second circuit board is arranged in the cavity in a manner that the second circuit board is perpendicular to the first circuit board; the surface of one side of the second circuit boardis provided with a second microphone component, wherein the one side of the second circuit board faces the side wall of the accommodating body; a hole sound guiding hole and a second sound guiding hole are formed in the side walls of the cover body and the accommodating body respectively; the first microphone component is used for receiving sound inputted through the first sound guiding hole; andthe second microphone component is used for receiving sound inputted through the second sound guiding hole. With the above technical schemes of the invention adopted, the space of the electronic assembly can be fully utilized. When the electronic assembly is applied to an electronic device, the lightening and thining of the electronic device can be benefitted.

The invention provides a micro camera well drill. The micro camera well drill comprises a left base, a right base and a bottom base station which is arranged below the left base and the right base and connected with the lower end surface of the left base and the lower end surface of the right base in a sliding mode; an extensible spring is connected between the left base and the right base; the outer side end surface of the right base is provided with a right fixing table rotating shaft; the outer side end surface of the left base is provided with a left fixing table rotating shaft; the right fixing table rotating shaft is connected with a right fixing table through a rotating shaft support and the left fixing table rotating shaft is connected with a left fixing table through a rotating shaft support; the bottom of the right base is provided with a right fixing device extensible motor and a right bottom wheel.

The invention discloses an automobile B-column capable of realizing multi-axis concentrated energy absorption. The automobile B-column comprises a B-column outer plate, a micro-cell filling layer, anda B-column inner plate. The micro-cell filling layer is a stereoscopic structure formed by successively arranging and combining multiple cell bodies in an X direction and a Y direction. The cell bodyis formed by connecting two symmetrical sub-cells. The sub-cell comprises a force transmitting part, a first vertical energy absorption part, a second vertical energy absorption part, a first horizontal energy absorption part, and a second horizontal energy absorption part. One end of the force transmitting part is connected with the first vertical energy absorption part through a first horizontal force transmitting plate, and the other end is connected with the first horizontal energy absorption part. The first vertical energy absorption part is connected with the second vertical energy absorption part. An included angle between the first vertical energy absorption part and the second vertical energy absorption part is 135-165 degrees. The first horizontal energy absorption part is connected with the second horizontal energy absorption part through a second horizontal force transmitting plate. The other end of the second horizontal energy absorption part is connected with the secondvertical energy absorption part. The automobile B-column is low in initial peak value during a collision process, stable in energy absorption process, and good in energy absorption effect.

The invention provides a structure for preventing noise and improving heat exchange performance in an automotive air-conditioning heating power expansion valve, which comprises an expansion valve body. The structure is characterized in that: a micropore valve sheet is arranged from the expansion valve body to an evaporator inlet, and is in close fit with the expansion valve body. In the structure, the micropore valve sheet is arranged from the expansion valve body to the evaporator inlet additionally, mixed gas liquid is subjected to porous flow split, which is similar to the function of a silencer, so the effect of noise reduction is achieved. In addition, the evaporation time is increased in the expansion valve, and the evaporation area of an evaporator is enlarged relatively to improve the refrigerating performance of the whole air conditioner.

The invention discloses a curtain wall board of a suspension type curtain wall, and the curtain wall board comprises a curtain wall board body, wherein the upper part of the curtain wall board body is provided with an upper hook part capable of being suspended on a cross keel of the curtain wall, and the lower part of the curtain wall board is provided with a lower hook part capable of being suspended on the cross keel of the curtain wall. The curtain wall board of the suspension type curtain wall has the advantages of simple structure, firmness and simpleness in connection and high installation efficiency.

The invention discloses an air conditioning air deflector and a manufacturing method of the same. The air conditioning air deflector comprises an arc metal material lining, at least one layer of sound-insulation wind deflector outer layer is arranged on the outer surface of the metal material lining, a fastening component connected with the upper end of the sound-insulation air deflector outer layer is arranged at the upper edge of the inner surface of the metal material lining, a connecting component connected with the lower end of the sound-insulation air deflector outer layer is arranged at the lower edge of the inner surface of the metal material lining, and a middle connecting piece is arranged in the middle of the inner surface of the metal material lining. The sound-insulation air deflector outer layers are arranged on the surface of the metal material lining, so that when an air conditioner is started, sound reduction, sound attenuation and noise reduction functions are achieved; by the additional arrangement of the sound-insulation air deflector outer layers, connecting clearances of air deflectors and air conditioning parts are greatly reduced, and water drops generated under the action of heat conduction are reduced; the sound-insulation air deflector outer layers are tightly connected with the metal material lining, so that convenience in assembly is achieved, production cost is greatly lowered.

The invention discloses a new type of metal processing drilling machine, comprising: a processing table, a slide bar, a support frame, a drill mechanism and a sound insulation cover; the slide bar is vertically fixed on the processing table, and the drill mechanism can be It is set up and down on the slide bar; wherein, the upper surface of the sound insulation cover is set on the drill bit mechanism through a plurality of springs, and the sound insulation cover is also provided with a drill that matches the drill bit in the drill bit mechanism through holes, the soundproof cover can cover the workpiece to be processed. The novel metal processing drilling machine overcomes the problem that the metal processing drilling machine in the prior art has high processing noise, which affects the working environment, and iron filings generated during processing are easy to splash and hurt people.

The invention relates to the technical field of a DC motor and particularly relates to a brush assembly. The brush assembly comprises brushes, a brush rack, brush holders and constant-force springs, and the brush holders are arranged on the brush rack. The brush assembly is characterized in that the cross section of the brush rack is cone-shaped, the brushes are provided with through holes, the through holes are communication holes which penetrate using surfaces of the brushes and surfaces opposite to the using surfaces, the brush holders are provided with slide grooves, a clamping support is fixed to two outer side positions of an inner end of each brush holder, each constant-force spring is a double-scroll coil spring with two ends provided with scrolls, middle parts of the constant-force springs abut against outer ends of the brushes, the middle segment of each spring and the outer end of the corresponding brush are sleeved in the slide groove of the corresponding brush holder, and two ends of each spring are supported by the corresponding clamping support. According to the brush assembly, the service life of the brushes is effectively prolonged, and the noise of the motor is reduced.

The invention relates to a double-geared roller crusher. The double-geared roller crusher comprises a feed hopper, a smashing chamber, an outlet hopper and a machine frame, wherein a plurality of baffles are arranged inside the feed hopper oppositely in a staggered mode, a first electromotor and a second electromotor are arranged on a supporting plate on one side of the smashing chamber, and sliding rails matched with the first electromotor and the second electromotor are arranged on the supporting plate; sliding devices matched with the sliding rails are arranged at the bottom end of the first electromotor and the bottom end of the second electromotor respectively, rotary shafts are connected to the output end of the first electromotor and the output end of the second electromotor respectively, and the free end of each rotary shaft extends into the smashing chamber and penetrates through the other side face of the smashing chamber; each rotary shaft in the smashing chamber is provided with a smashing roller, a plurality of smashing teeth are arranged on each smashing roller, and the smashing teeth on the smashing roller connected to the first electromotor are engaged with the smashing teeth on the smashing roller connected to the second electromotor; a water tank is arranged on the other side of the smashing chamber, a pressure pump is arranged in the water tank, a water pipe is connected to the output end of the pressure pump, and the other end of the water pipe extends into the smashing chamber.

The invention discloses a multifunctional computer case which comprises a rack, wherein the rack consists of a right side plate, a left side plate, a bottom plate and a top cover; a power supply anti-vibration pad is fixedly arranged at the upper part of the inner side of the left side plate, and an air inlet is formed in the right side plate; an air inlet fan is arranged in the rack directly facing the air inlet; an upper top cover dustproof net and a lower bottom plate dustproof net are respectively arranged on the bottom plate and the top cover; a fixed magnetic damping device is arranged at the lower part of the rack in a sleeving way. The multifunctional computer case has the benefits that as the fixed magnetic damping device is arranged at the lower bottom of the rack in a sleeving way, and a magnetic separation plate is arranged on the periphery of the fixed magnetic damping device, the work of other parts in the rack cannot be influenced, and the damage to an electric component inside the rack caused by too intense vibration can also be prevented at the same time, so that the case is effectively protected; meanwhile, as the dustproof nets are arranged on the top cover and at the bottom, the multifunctional computer case has a good dustproof effect; the multifunctional computer case integrates multiple functions and is simple in structure, reasonable in design and low in cost.

The invention discloses an underwater sub-wavelength local resonance type acoustic metamaterial which comprises a water area 1, a stainless steel cylindrical shell 2 and a stainless steel three-fork star-shaped cylinder 3. Included angles among three outer forks of the stainless steel three-fork star-shaped cylinder 3 are 120 degrees, and an inner cavity of the cylinder is evenly divided into three fan-shaped cavities 9, 10 and 11. The three fan-shaped cavities 9, 10 and 11 are air domains. The underwater sub-wavelength local resonance type acoustic metamaterial disclosed by the invention hasfour sections of extremely wide complete band gaps in a frequency band [0Hz, 60000Hz]. In a complete band gap, propagation of sound waves is completely cut off and cannot continue to propagate forwards, and the possibility that an underwater object is detected by sonar due to radiation noise of the underwater object is reduced. The underwater sub-wavelength local resonance type acoustic metamaterial is provided with a Dirac point, and the standardized frequency of the lowest-frequency Dirac point is 0.0072 and is far lower than 1. The sound waves near the Dirac point frequency can realize zero-phase-difference propagation without changing the wavefront formation of the sound waves, and the possibility that underwater obstacles are actively detected by sonar is reduced.

The invention discloses a noise reduction device for an automobile exhausting system. The noise reduction device comprises a noise reducer, a noise reduction controller and a microphone for acquiringnoise, wherein the microphone is arranged at the exhausting end of an exhausting pipeline and is connected with the noise reduction controller, and the noise reducer is connected with the noise reduction controller. The noise reducer is arranged between a three-way catalyst and a silencer, the air inlet end of the noise reducer is connected with the exhausting end of the three-way catalyst, the exhausting end of the noise reducer is connected with the air inlet end of the silencer, and the microphone is arranged at the exhausting end of the silencer. The noise reducer is a cooler, the cooler is communicated with a cooling system of an engine, the cooler is provided with a flow valve, and the flow valve is connected with the noise reduction controller and controls the flow of coolant entering the cooler. The coolant led into the cooler is cool the gas in the exhausting pipeline, accordingly the noise is reduced, the cooler is communicated with the cooling system of a whole automobile, and circulation of the coolant is achieved. The invention also discloses a noise reduction method for the automobile exhausting system.

The invention mainly discloses an efficient kitchen garbage disposer and belongs to kitchen cleaning devices.The efficient kitchen garbage disposer mainly comprises an upper cavity, a middle cavity, a lower cavity, an arc-shaped cutter and a circular truncated cone grinding tool.The upper cavity, the middle cavity and the lower cavity are connected through screws, sealing rings are arranged at the connecting ends, a motor is installed in the lower cavity, the circular truncated cone grinding tool is arranged in the middle cavity, the lower end of a transmission shaft penetrates through the lower cavity and then is connected with the motor, the upper end of the transmission shaft is in interference fit with a central square hole in the bottom of the circular truncated cone grinding tool, a supporting disc is installed between the upper cavity and the lower cavity, the arc-shaped cutter is arranged in the upper cavity, the middle of the arc-shaped cutter is matched with the supporting disc, and the lower portion of the arc-shaped cutter is embedded in a square hole in the top of the circular truncated cone grinding tool, a splash guard is arranged in an end opening of the upper cavity and connected with the end opening through threads, and a waste discharging port is formed in the upper end of the lower cavity.The efficient kitchen garbage disposer has the advantages that cutting and grinding are combined, the smashing efficiency of garbage is improved, the overall structure design is ingenious, and the performance is reliable.