46results about How to "Good low frequency" patented technology

A method of production of a reduction resistant dielectric ceramic composition having a superior low frequency dielectric characteristic and further improved in accelerated lifetime of insulation resistance, specifically a method of production of a dielectric ceramic composition containing a main component including a dielectric oxide of a specific composition, a first subcomponent including a V oxide, a second subcomponent containing an Al oxide, a third subcomponent containing an Mn oxide, and a fourth subcomponent containing a specific sintering aid in a specific ratio, including a step of mixing at least part of the materials of the subcomponents excluding one or both of at least the material of the third subcomponent and material of the fourth subcomponent with the starting materials prepared for obtaining the material of the main component to prepare the pre-reaction material, a step of causing the prepared pre-reaction material to react to obtain a reacted material, and a step of mixing the materials of the subcomponents excluded when preparing the pre-reaction material with the obtained reacted material to obtain a dielectric ceramic composition.

The invention relates to an air gun array earthquake source three-dimensional space combination method for offshore earthquake exploration. The method comprises the steps of determining the total capacity of an air gun array earthquake source, and the number of subarraies, determining the capacity of each subarray and the capacity of each subarray unit in each subarray, determining the relative positions of large capacity air guns and small capacity air guns, determining the positions of all the subarraies in an air gun array, determining the optimal immersing depth of the air gun array, selecting air gun array plane arrangement parameters corresponding to simulating wavelets meeting exploration requirements, determining the optimal three-dimensional space combination mode of the air gun array and related parameters of the immersing depth of upper sources and the lower sources and the like, so that a delayed simulating three-dimensional space combination stereoscopic air gun array earthquake source can be obtained, and the delayed simulating three-dimensional space combination stereoscopic air gun array earthquake source is final air gun earthquake source three-dimensional space combination for offshore earthquake exploration. The air gun combination arrangement mode designed through the air gun array earthquake source three-dimensional space combination method is distinct in gradation, the optimal air gun combination arrangement mode is provided for different construction conditions and different offshore exploration environments, and therefore optimal far field wavelets in the current environment can be obtained. The air gun array earthquake source three-dimensional space combination method for the offshore earthquake exploration can be directly used in the outdoor offshore earthquake exploration process.

The timing recovering circuit includes module of detecting data phase, frequency division module of dividing N, data buffering module and module of adjusting recovery timing. Recovery of timing data is carried out for RZ signal through buffering technique of processing data effectively so that recovery timing can be locked rapidly. The invention features removing dithering, and is applicable to recover timing data in procedure of synchronous data transmission.

The invention provides a system and method for improving the voice quality of a mobile terminal in a receiver mode. The system for improving the voice quality of the mobile terminal in the receiver mode comprises a first signal channel and a second signal channel which are arranged in parallel; the first signal channel comprises a first power amplifier and a receiver which are electrically connected; the second signal channel comprises a second power amplifier and a vibration motor which are electrically connected; the receiver and the vibration motor simultaneously receive and play voice signals; the first power amplifier and the second power amplifier are respectively used for adjusting the gains of the voice signals output to the receiver and the vibration motor. According to the system and the method provided by the invention, when the receiver sounds, the vibration motor vibrates synchronously according to the voice signals and drives the mobile phone to vibrate and sound; the voice generated by the vibration of the vibration motor and the voice generated by the receiver are combined; the better voice quality is obtained; and the better low frequency, the better high frequency or the higher loudness is obtained.

The invention discloses a laser gyro shaking stripping device which is used for adaptively stripping a laser gyroscope shaking signal by adopting an LMS (Least Mean Square) algorithm based on an adaptive compensation technology. The sampling frequency of the stripping device is integral multiples of shaking frequency. A sine and a cosine reference signals for stripping are obtained by using one path of sampling differential signals through simple and digital delay, system input and output response is unchangeable when approximating, and thus shaking stripping effect can be improved.

The invention relates to a strip-shaped loudspeaker box with mirror image type low-frequency radiators. A box body is in a long flat strip shape. Low-frequency radiator installation holes symmetrical in position are formed in the upper and lower surfaces of the right half part, in the long axis direction, of the box body respectively, and the two low-frequency radiators are correspondingly installed in the two upper and lower low-frequency radiator installation holes in a mirror symmetry mode. A mid-low-pitch loudspeaker installation hole is formed in the left half part, in the long axis direction, of the box body, a mid-low-pitch loudspeaker is installed in the mid-low-pitch loudspeaker installation hole, and the mid-low-sound loudspeaker radiates sounds towards the part over the box body. A high-pitch loudspeaker installation table is arranged on the front side face of the left end, in the long axis direction, of the box body, a high-pitch loudspeaker is installed on the high-pitch loudspeaker installation table, and the high-pitch loudspeaker radiates sounds towards the part right ahead of the box body. The strip-shaped loudspeaker box has the acoustic properties of being small in distortion, good in low frequency, capable of bearing high power and excellent in high-frequency performance; the transient stability of the loudspeaker box can be improved, and thus the loudspeaker box can achieve a good sound effect when radiating low-frequency sounds.

A piezoelectric microelectromechanical systems diaphragm microphone can be mounted on a printed circuit board. The microphone can include a substrate with an opening between a bottom end of the substrate and a top end of the substrate. The microphone can have two or more piezoelectric film layers disposed over the top end of the substrate and defining a diaphragm structure. Each of the two or more piezoelectric film layers can have a predefined residual stress that substantially cancel each other out so that the diaphragm structure is substantially flat with substantially zero residual stress. The microphone can include one or more electrodes disposed over the diaphragm structure. The diaphragm structure is configured to deflect when the diaphragm is subjected to sound pressure via the opening in the substrate.

The invention discloses a seismic elastic impedance low-frequency information extraction method and system, and a storage medium. The method comprises the following steps: obtaining seismic data and actually measured elastic impedance data; inverting elastic impedance data through a neural network according to the seismic data; forward modeling seismic data are generated according to the elastic impedance data, and a seismic data loss value is obtained; obtaining a loss value of the elastic impedance according to the elastic impedance data and the actually measured elastic impedance data; obtaining a minimum total loss value and a low-frequency curve according to the seismic data loss value and the loss value of the elastic impedance; performing seismic inversion and reservoir prediction based on the minimum total loss value and the low-frequency curve; according to the scheme, the neural network method is introduced for seismic low-frequency information extraction, the extracted low-frequency characteristics are good, the calculation efficiency is high, the reservoir prediction precision can be remarkably improved, the exploration risk is reduced, and the method can be widely applied to the technical field of geophysical exploration.

The invention discloses an elastomer loudspeaker box system which comprises a loudspeaker box, a loudspeaker single body, a barrier plate and a bottom plate. The loudspeaker is made of an elastomer material, and the pipe wall is bent into a corrugate-shaped box shape, therefore the loudspeaker box body has elasticity and can freely extend and contract. The loudspeaker single body is fixedly arranged on the barrier plate, one end of the loudspeaker box is fixed on the barrier plate, and the other end thereof is sealed by the bottom plate, therefore the loudspeaker single body, the loudspeaker box and the bottom plate together form a closed box system. The loudspeaker single body and the loudspeaker box body can extend, contract and swing to generate resonance; the elastic box body performsthe function of the acoustic radiator, and radiates low frequency; and the low frequency response is extended to the lower end, the purity of sound is enhanced, and the property of low sound is improved.

The invention relates to a sound box based on an oppositely buckled passive radiator. The sound box comprises a prolate box body, a high pitch loudspeaker mounting hole and a mid-bass loudspeaker mounting hole distributed along the length direction of the box body are opened in the top of the box body, a high pitch loudspeaker unit is mounted in the high pitch loudspeaker mounting hole, and a mid-bass loudspeaker unit is mounted in the mid-bass loudspeaker mounting hole; a passive radiator unit is mounted on the right side of the mid-bass loudspeaker unit through a radiator bracket, and the central axial line of the passive radiator unit is mutually parallel to the central axial lines of the high pitch loudspeaker unit and the mid-bass loudspeaker unit; the radiator bracket is provided with two sound outlets which are symmetrically arranged at 180 degrees, the two sound outlets respectively face to front and back side faces of the box body, and sound outlet holes communicated with the sound outlets are respectively formed in the front and back side faces of the box body. The sound box provided by the invention both has the advantages of the passive radiator sound box and can perfect the defects of poor vertical transient stability, high cut-off frequency and large total loss Ql value, so as to ensure a good sound effect for the sound box.

The invention relates to a low-frequency and easy-to-confuse criminal name prediction method integrated with case auxiliary sentences, and belongs to the technical field of natural language processing. The method comprises the steps that firstly, case auxiliary sentences are constructed based on the judicial field, and the case auxiliary sentences are drafted as external knowledge to serve as mapping between case description and criminal names; calculating case description and case auxiliary sentence multi-granularity characteristics based on word level and character level; two-way mutual attention is constructed by means of case auxiliary sentences and case description, information interaction between the case description and the case auxiliary sentences is enhanced, case description multi-granularity tendency characteristics guided by the case auxiliary sentences are extracted, and accordingly low-frequency and easy-to-confuse criminal name prediction accuracy is improved. Accordingto the method, the F1 value is increased by 13.2% to the maximum extent, the accuracy is increased by 4.5% to the maximum extent, the low-frequency crime prediction F1 value is increased by 4.3%, andthe easy-to-confuse crime prediction F1 value is increased by 8.2%.

The invention relates to terminal equipment and a signal processing method. The terminal device includes: a screen; a sound cavity; the sound absorbing medium is positioned in the sound cavity; the vibrating diaphragm is attached to the screen, and the vibrating diaphragm and the sound absorbing medium are located on the two opposite sides in the sound cavity respectively; wherein the vibrating diaphragm is used for generating a vibration signal, and the vibration signal is used for triggering the screen to vibrate to generate a sound signal. According to the embodiment of the invention, the performance of each frequency band in the sound signal can be improved through the sound cavity and the sound absorption medium in the terminal equipment while the sound production of the screen is realized, so that the frequency response curve corresponding to the sound signal is flatter, and the sound production effect of the screen is improved.

Wavy riblets are disposed at one or more auditorily important acoustical boundary layers of a sound producing device. Wavy riblets can be deployed directly onto the surface of the device, and / or onto a film or other carrier that is then positioned in or on the device. Wavy riblets can be advantageously deployed in sets, in a herringbone pattern, and sets of smaller riblets can be disposed between sets of larger riblets. Wavy riblets can also be superimposed onto other wavy or non-wavy riblets. Contemplated sound producing devices include speakers, musical instruments, fan blades and ducts.

The present invention relates to a screen sound emission structure for a terminal. The screen sound emission structure comprises a screen and a rear shell; the screen and the rear shell are in seal connection so as to form a sealed front cavity; a rear cavity for balancing part of the pressure of a gas in the front cavity is defined in the front cavity; a magnetic piston is arranged in the rear cavity; the magnetic piston can move in a reciprocating manner and can be used for compressing the gas in the front cavity, so that a screen can be deformed, and therefore, sound pressure can be generated, and sound is emitted; and a conductive coil that drives the magnetic piston to move through electromagnetic induction is wound around the magnetic piston. According to the screen sound emission structure for the terminal of the invention, the size of the front cavity is large, so that the screen sound emission structure has the advantages of good low frequency effect, large screen area, capability of pushing a large volume of external air and large generated sound pressure; and the screen and the rear shell are sealed to form the front cavity, and therefore, the screen sound emission structure has high three-prevention performance and is not affected by external environment.

The invention discloses a vehicle suspension attitude measurement method and system. A direction cosine matrix is obtained through attitude calculation in a measurement processing process, the acceleration data of a carrier is converted into an inertial coordinate system, the influence of gravity is eliminated, and the motion (non-vehicle driving motion) of a wheel bracket and a vehicle body in a vehicle suspension motion boundary can be accurately measured, so that the obtained telescopic motion data of the shock absorber is more accurate; and meanwhile, the method and the system have good low-frequency or zero-frequency measurement precision, are not affected by the terrain and the vehicle attitude in the measurement process, can accurately measure the pose motion state of the key point in a vehicle suspension system, and provide reliable reference for detection and control of the vehicle suspension system.

The invention discloses a loudspeaker and electronic equipment. The loudspeaker comprises a frame, a magnetic circuit system, a first vibration system and a second vibration system. The magnetic circuit system is fixed in the frame, a first magnetic gap and a second magnetic gap are formed on one end face of the magnetic circuit system, a third magnetic gap is formed on the other end face of the magnetic circuit system, and the second magnetic gap and the third magnetic gap are back to back and are communicated; the first vibration system is provided with a first vibrating diaphragm and a first voice coil, the first vibrating diaphragm covers the frame and is opposite to the first magnetic gap, and the first voice coil is connected to the first vibrating diaphragm and is inserted into the first magnetic gap; the second vibration system is provided with a second vibrating diaphragm and a second voice coil, the second vibrating diaphragm covers the basin frame and is opposite to the third magnetic gap, and the second voice coil is connected to the second vibrating diaphragm and is inserted into the second magnetic gap and the third magnetic gap at the same time; when the second voice coil is powered on, the second magnetic gap and the third magnetic gap apply acting force in the same direction to the second voice coil. According to the invention, the requirements of various small electronic devices on tone quality can be better met.

The invention provides a power amplifier. The power amplifier comprises a third capacitor, a first transistor, a first-stage matching circuit, a second transistor, a second-stage matching circuit, a third transistor, an output matching circuit, a first-stage series feedback network circuit bridged between a base electrode of the first transistor and the ground, and a second-stage series feedback network circuit bridged between a base electrode of the second transistor and the ground. The first-stage series feedback network circuit is used for adjusting the circuit equivalent capacitance value of the first-stage series feedback network circuit according to the first control voltage so as to adjust the gain of the first transistor. The second-stage series feedback network circuit is used for adjusting the circuit equivalent capacitance value of the second-stage series feedback network circuit according to the second control voltage so as to adjust the gain of the second transistor. The invention also provides a radio frequency chip. By the adoption of the technical scheme, the gain of the power amplifier can be linearly and continuously adjusted, and the effect of restraining low frequency and high frequency outside the working frequency band is good.

Disclosed is a magneto-resistive seismic wave detector. The magneto-resistive seismic wave detector comprises a magneto-resistive element, a magnet, a housing and a spring. The spring is arranged inside the housing, and both ends of the spring are fixed onto the two inner walls of the housing; the magnet is mounted on the spring and in the middle of the spring; the magneto-resistive element is arranged under the magnet, the lower end of the magneto-resistive element is fixed onto the bottom surface of the housing, and the geometric center of the magneto-resistive element is located in the linear distribution zone of the magnetic field produced by the magnet. When receiving seismic waves, under the action of the spring, the magnet and the magneto-resistive element interact with each other to generate inertial oscillation and accordingly can produce relative displacement to change the magnetic field, so that seismic signal collection can be completed. The magneto-resistive seismic wave detector can effectively collect the seismic signals of deep stratums, improve the seismic exploration accuracy, meet the requirements of precise geological exploration and obtain obvious economic benefits.

The invention relates to a virtual seven-channel strip sound box. A left-end-arranged loudspeaker is arranged on the left end face of a strip box body; a right-end-arranged loudspeaker is mounted on the right end face of the strip box body; the left-end-arranged loudspeaker and the right-end-arranged loudspeaker are symmetrical to each other in a mirrored manner; a left-front-arranged loudspeaker, a middle-front-arranged loudspeaker and a right-front-arranged loudspeaker are mounted on the front lateral surface of the strip box body; the middle-front-arranged loudspeaker is positioned at the middle position of the strip box body in the long axis direction; the left-front-arranged loudspeaker and the right-front-arranged loudspeaker are symmetrically arranged at both left and right sides of the middle-front-arranged loudspeaker; a left-top-arranged loudspeaker and a right-top-arranged loudspeaker which are bilaterally symmetrical are mounted at the top of the strip box body; a projection position of the left-top-arranged loudspeaker on a plane is positioned between the left-front-arranged loudspeaker and the middle-front-arranged loudspeaker; and a projection position of the right-top-arranged loudspeaker on the plane is positioned between the middle-front-arranged loudspeaker and the right-front-arranged loudspeaker. The virtual seven-channel strip sound box disclosed by the invention can achieve a stereoscopic surrounding effect, improves transient stability of a sound system, and is low in distortion, good in low frequency and high in bearable power.

Herein provided is a sound-insulating laminated structure which is excellent in the ability of insulating low frequency sounds whose frequency falls within the range of from 200 to 1000 Hz. The sound-insulating laminated structure comprises a first glass wool layer, a metal foil layer free of any opening and a second glass wool layer. The first and second glass wool layers are ones each prepared by collecting and combining short glass fibers through the application of an uncured thermosetting phenol resin to the short glass fibers to thus give a web of glass wool prepreg and then molding, with heating, the web into a sound-insulating laminated structure having a desired shape.

A piezoelectric microelectromechanical systems diaphragm microphone can be mounted on a printed circuit board. The microphone can include a substrate with an opening between a bottom end of the substrate and a top end of the substrate. The microphone can have two or more piezoelectric film layers disposed over the top end of the substrate and defining a diaphragm structure. Each of the two or more piezoelectric film layers can have a predefined residual stress that substantially cancel each other out so that the diaphragm structure is substantially flat with substantially zero residual stress. The microphone can include one or more electrodes disposed over the diaphragm structure. The diaphragm structure is configured to deflect when the diaphragm is subjected to sound pressure via the opening in the substrate.

The invention discloses a loudspeaker module, and belongs to the technical field of audio-video equipment. The module comprises: a first cavity; a second cavity which is arranged adjacent to the firstcavity; and a vibration module which is arranged in the first cavity, wherein the vibration module comprises a first vibrating diaphragm and a second vibrating diaphragm which are horizontally arranged at intervals. The first cavity comprises a first sub-cavity and a second sub-cavity which are located on the two sides of the vibration module respectively, and the second sub-cavity is communicated with the second cavity. According to the loudspeaker module provided by the invention, the condition that sharp peaks and valleys exist in a medium-high frequency curve can be improved, and a good hearing feeling is achieved; the arrangement of a powder net structure can increase the ventilation capacity between the second sub-cavity and the second cavity and prevent foreign matters in the product from contacting the second vibrating diaphragm to influence the tone quality, and a rear cavity is directly arranged below the second vibrating diaphragm, so that the design compactness of the product is improved, the space of the rear cavity is greatly increased, the low frequency is further improved, the product quality is improved, and the medium-high frequency adjusting function of the second vibrating diaphragm is not influenced.

The invention discloses a five-phase permanent magnet synchronous motor open-circuit fault-tolerant position-free control method based on a rotor flux observer. According to the strategy, on the basis of a fault-tolerant model, a sliding-mode observer based on an exponential reaching law is constructed to obtain a counter electromotive force signal; secondly, in order to suppress the influence of direct current bias and low-frequency and high-frequency harmonic waves in the observed counter electromotive force on the rotor position observation precision, an improved second-order generalized integrator is designed, and the improved second-order generalized integrator and a sliding-mode observer are cascaded to form a rotor flux linkage observer; thirdly, rotor position information is extracted from a rotor flux linkage by adopting a phase-locked loop technology; and finally, combining the rotor flux observer with a fault-tolerant control strategy. The strategy effectively suppresses direct current bias and low-frequency and high-frequency disturbance in observation of the counter electromotive force, improves the rotor position estimation precision of the five-phase permanent magnet synchronous motor under the open-circuit fault, and realizes position-free high-performance operation of the motor under the open-circuit fault.

The invention relates to the technical field of brake calipers and in particular relates to a pair of eccentric only-pull structure type hydraulic brake calipers. The pair of eccentric only-pull structure type hydraulic brake calipers comprises a guide pin, a buffer sleeve, holding springs, an inner friction block, an outer friction block, an eccentric shell, a piston and an only-pull structure bracket. Two sides of the eccentric shell and the only-pull structure bracket are connected through the guide pin and the buffer sleeve, the eccentric shell and the outer friction block are connected through the holding spring, and the inner friction block and the piston are connected through the other holding spring. Compared with the prior art, the only-pull structure bracket with an outer beam isdesigned, so that the integral rigidity is improved, the machining stability is improved greatly, and the tolerance zone is reduced greatly, and therefore, more favorable support is provided to improve eccentric wear, noise and drag. The eccentric shell is matched with the only-pull structure bracket, so that the eccentric wear of a friction plate is reduced to the maximum extent, and low frequency and knock abnormal sound noises are improved. The drag, eccentric wear and noise conditions of the hydraulic brake calipers are also improved well.

The invention relates to the related field of PFC systems, in particular to a bidirectional PFC system adopting digital control. The bidirectional PFC system comprises a PFC main circuit, a voltage outer loop control module, a current inner loop control module and a main control chip. Through the discretization of a PIR algorithm, a totem pole PFC forward and reverse double closed-loop control algorithm is carried out, and after the algorithm is improved, the PIR algorithm is better in low-frequency and high-frequency control, the system tracking is better, a steady-state error is smaller, and the overall performance is comprehensively improved, so that the performance of an OBC is integrally improved.

The invention relates to a magnetorheological fluid vibration reduction platform with quasi-zero stiffness. The platform comprises a movable platform mechanism and a peripheral fixed platform mechanism; the peripheral fixed platform mechanism consists of an upper fixed platform, a bracket and a lower fixed platform, and is fixed through bolts and nuts; the movable platform mechanism is arranged in the peripheral fixed platform mechanism; a movable platform is hinged to a single-cylinder magnetorheological fluid vibration reducer through a single-cylinder magnetorheological fluid vibration reducer upper spherical hinge base; the upper fixed platform is connected above the movable platform through three double-cylinder magnetorheological fluid vibration reducers; the lower fixed platform is connected below the movable platform through thesingle-cylinder magnetorheological fluid vibration reducer; the movable platform is positioned in the middle position; the magnetorheological fluid vibration reducers in the upper and lower positions form a vibration reduction system with quasi-zero stiffness in space; multiple displacement sensors or multiple gravity sensors are uniformly distributed at the periphery of the movable platform for detecting a vibration direction and feeding backthe same to a control system; and the control system adjusts current values of all dampers of the double-cylinder magnetorheological fluidvibration reducers according to feedback signals so as to adjust damping numerical values of the dampers in all positions.