143results about How to "Meet the needs of the application" patented technology

The invention discloses a real-time panoramic image stitching method of aerial videos shot by an unmanned plane. The method comprises the steps of: utilizing a video acquisition card to acquire images which are transmitted to a base station in real time by an unmanned plane through microwave channels, carrying out key frame selection on an image sequence, and carrying out image enhancement on key frames; in the image splicing process, firstly carrying out characteristic detection and interframe matching on image frames by adopting an SURF (speeded up robust features) detection method with good robustness; then reducing the series-multiplication accumulative errors of images in a frame-to-mosaic image transformation mode, determining images which are not adjacent in time sequence but adjacent in space on a flight path according to the GPS (global positioning system) position information of the unmanned plane, optimizing the frame-to-mosaic transformation relation, determining image overlapping areas, thereby realizing image fusion and the panoramic image construction and realizing real-time effect of carrying out flying and stitching simultaneously; and in image transformation, based on adjacent frame information in a vision field and adjacent frame information in airspace, optimizing image transformation to obtain the accurate panoramic images. The stitching method has good real-time performance, is fast and accurate and meets the requirements of application occasions in multiple fields.

The invention discloses a manufacturing method of a high-strength, high-modulus and low-shrinkage polyester industrial yarn. The manufacturing method comprises the processes of preparation of a highly viscous melt polyester raw material, metering, spinning, cooling, oil applying, drawing, heat shaping and winding formation; the cooling comprises slow cooling, precooling, cooling in an air free zone and air blast cooling in sequence; the precooling part uses a driven hollow-out successive annular strip. Through the introduction of a precooling device, irregularity caused by tow shaking due to move-down of a curing point of a fiber is reduced, the linear density deviation is controlled within a lower range, and orientation and crystallization of an as-spun fiber are reduced, so that the high-strength, high-modulus and low-shrinkage polyester industrial yarn is obtained; and the high-strength, high-modulus and low-shrinkage polyester industrial yarn has the advantages of high breaking tenacity, high initial modulus, low linear density deviation, low breaking elongation and lower dry-heat shrinkage rate and can be used for preferably satisfying requirements on application.

The invention discloses an ultrahigh-frequency wireless sensing tag which combines the passive operating mode with the semi-active operating mode. The ultrahigh-frequency wireless sensing tag comprises a radio frequency rectifying circuit, an ASK signal demodulation circuit and a back reflection modulator circuit which can change the input impedance of an antenna, in this way, wireless receiving and transmitting of sensing data can be achieved through the tag in a passive mode, and power consumption and cost are reduced. When the passive operating mode of the tag is started, an on-chip sensor can be started for acquisition and transmission of the sensing data; when the semi-active operating mode of the tag is started, an off-chip sensor can be started for acquisition and transmission of the sensing data. According to the sensing tag, a command specified in ultrahigh-frequency RFID international standard ISO 18000-6C and EPC C1G2 is used for starting of the on-chip sensor or the off-chip sensor and controlling and uploading of the data, in this way, a special control chip does not need to be designed, and any ultrahigh-frequency reader-writers according with the international standard can be used for acquiring and uploading the sensing data.

The invention relates to a manufacturing method for superlow shrinkage type PET industrial yarn, which is characterized in that the superlow shrinkage type PET industrial yarn is manufactured through selecting and controlling cooling conditions, and the technological process is as follows: hyperviscous melting to polyester raw materials, metering, spanning, cooling, oil supplying, stretching, hot shaping, and reeled forming. For lowing the irregularity and shrinkage percentage of fiber, a slow cooling device is arranged in the production of industrial yarn, a precooling device adopted is a hollow stepped ring-shaped belt comprising an upper part and a lower part, through holes with the diameters of 5 to 7 mm are uniformly distributed in the upper part of the ring-shaped belt, through holes with the diameters of 3 to 4 mm are uniformly distributed in the lower part, and the hole arrangement densities are the same. The natural target of the PET industrial yarn is as follows: the fracture strength is equal or greater than 7.0 cN / dtex, the breaking elongation is 20.0 plus or minus 1.5 percent, and the dry heat shrinkage percentage under the test conditions of 170 DEGC, 0.05cN / dtex reaches 1.9 plus or minus 0.25 percent.

The present invention relates to wireless sensor network technology and data collecting field, and discloses a universal node device of wireless sensor network, wherein the universal node device comprises the following components: a wireless radio frequency receiving / transmitting unit which is used for realizing the communication between other node in a wireless sensor network and the base station; a microprocessor unit which is used for controlling the communication between universal nodes in the wireless sensor network and realizing various calculations; a universal sensor interface unit which is used for providing appropriate interface for various special sensor nodes; a universal peripheral interface unit which is used for the connection between the universal node and the outer PC for realizing the communication between the upper machine and the universal node; and a power management unit which is used for the power supplying of each unit in the universal node and detecting the health condition of the power supply. The universal node device according to the invention realizes the universal node satisfying the least function set of network node of wireless sensor, and comprises calculating function and network function. The quick development of various sensor nodes is realized. The quick construction of wireless sensor network supporting a plurality of protocols is realized. The versatility requirement of network node of wireless sensor is satisfied.

The invention discloses a method for preparing a high-strength solid buoyancy material. The method comprises the steps as follows: a coupling agent in a mass ratio of (0.2:100) with hollow microspheres is adopted to perform pretreatment on 1-20 parts of hollow microspheres; 100 parts of resin, 0-60 parts of a curing agent, 0-15 parts of a toughening agent, 0-5 parts of a dispersing agent and 0-10 parts of a diluent are stirred and mixed to obtain a resin system material, the pretreated hollow microspheres and 1-30 parts of small fiber balls are gradually added into the resin system material step by step, the mixture is slow stirred and uniformly mixed, and original slurry is obtained; and the original slurry enters an injection molding process and is subjected to demolding so as to obtain the high-strength solid buoyancy material. Compared with a traditional solid buoyancy material, the high-strength solid buoyancy material has higher compressive strength, lower density and water permeability and good processability simultaneously.

The invention relates to a complementary metal oxide semiconductor (CMOS)-process-based Hall switch offset voltage elimination method and a CMOS-process-based Hall switch offset voltage elimination circuit. A first clock signal and a second clock signal which are not overlapped with each other are adopted based on a rotary current method, wherein the first clock signal controls the amplification and storage of Hall voltage when a Hall slice is in a 0-degree state, and divides the second clock signal into a third clock signal and a fourth clock signal; the third clock signal controls the amplification and storage of the Hall voltage in a 90-degree state; and the fourth clock signal controls operations and comparison between the Hall voltage and threshold voltage in the 0-degree state and the 90-degree state to eliminate the offset voltage of the Hall slice. Compared with the prior art, the invention can use relatively fewer components and parts based on a CMOS process, so that a Hall switch can be applied to the detection of weak magnetic fields under the requirements of miniaturization and low power consumption.

The invention relates to a citizen interaction system in city planning, which comprises a planning geographic information management platform, a planning geographic information collecting and updating platform, a planning summarized information database, an information processor, a network transmission unit and an interaction display terminal which are arranged in a server, wherein the planning summarized information database is managed by the planning geographic information management platform and the planning geographic information collecting and updating platform; and the planning summarized information database is connected with the network transmission unit and the interaction display terminal. City planning and design results, planning examination and approval business, tri-dimensional virtual city, city satellite remote sensing information and related multimedia information are integrated into a whole body to build the citizen interaction system in city planning, viewing of the related information of city planning becomes convenient for citizens the real-time inquiry of project status of planning examination and approval can be realized, an electronic original map browsing platform of city design and planning and applying for building is provided, and government information publicity, city planning propaganda, sunlight planning service and planning knowledge popularization are integrally integrated.

The invention discloses a Power over Ethernet (PoE) port overvoltage comprehensive protection circuit and a method for realizing the circuit. The PoE port overvoltage comprehensive protection circuit comprises two-stage protection circuits, wherein the first-stage protection circuit adopts a triode gas discharge tube and is used for discharging lightning stroke current to the ground; the second-stage protection circuit adopts a clamp type overvoltage protection device and is used for carrying out first-stage residual voltage and electrostatic protection; a resistor and common-mode inductor combination circuit is adopted between the first-stage protection circuit and the second-stage protection circuit and is used for coordinating performance characteristics among the two-stage protection circuits and the device so as to achieve the effect of decoupling between the first-stage protection circuit and the second-stage protection circuit. Owing to the PoE port overvoltage comprehensive protection circuit, the balance of protection circuits can be enhanced and the amplitude and energy for conversion from common-mode overvoltage to differential-mode overvoltage can be reduced so as to improve the protection effect.

The invention discloses a manufacturing method for high-modulus low-shrinkage PET industrial yarn, and the technological process of the method is as follows: hyperviscous melting to polyester fiber raw materials, metering, spinning, cooling, oil applying, stretching, hot shaping and reeled forming, wherein the cooling process sequentially comprises four parts including slow-cooling, pre-cooling, calm zone cooling and blow cooling, and the pre-cooling part adopts a passive hollow ring-shaped belt device. Through the introduction of the pre-cooling device, the irregularity caused by tows quivering produced under the down moving of a solidification point of fiber can be reduced, the deviation ratio of linear density can be controlled within a lower range, the purpose of reducing orientation and crystallization of embryo fiber is achieved, finally high-modulus low-shrinkage PET industrial yarn can be obtained, the high-modulus low-shrinkage PET industrial yarn has the advantages of high modulus, low dry heat shrinkage percentage, low breaking elongation and low linear density deviation ratio, and practical application can be well met.

The invention relates to a method and a device for dynamically evaluating the reliability of a network. The method comprises the following steps: I, capturing network topological information; II, judging whether the first evaluation is carried out, executing the step III if yes, and executing the step VI if no; III, determining a source point and a targe node of the network to be evaluated; IV, acquiring network fault data and creating a database; V, obtaining a network path function OBDD (Ordered Binary Decision Diagram), evaluating the reliability of the network by an OBDD-based side expansion algorithm and entering the step IX; VI, searching the variation of the network topological information; VII, acquiring newly increased fault data and inputting the newly increased fault data into the database; VIII, evaluating the reliability of the network by the network path function OBDD obtained in the last evaluation process and an OBDD-based dynamic evaluation algorithm; and IX, outputting a network reliability evaluation result and an evaluation suggestion. The device comprises a topological analysis unit, a fault data acquisition unit and a reliability dynamic evaluation unit. The method and the device are suitable for the network which is dynamically changed and can be used for rapidly and efficiently evaluating the reliability of the network; and the repeated calculation is avoided and the efficiency is improved. The method and the device are suitable for various network systems.

A method for preparing a spherical alumina of high purity, relates to the preparation of alumina of high purity which is especially suitable to the used in the fields such as compact fluorescent lamp, illuminating material for PDP and LED and transparent ceramics, monocrystal of sapphire, monocrystal of ruby and polishing of paint of car. Its characteristics are that aluminum ammonium sulfate and ammonium hydrogen carbonate are used as the raw material to react into nanometer structure spherical aluminum ammonium carbonate AACH in the container with agitation, and the nanometer structure spherical ª†-Al2O3 and ª‡- Al2O3 are obtained by filtration, washing and roasting. The spherical alumina of high purity has remarkable liquidity, high mechanic strength, infragile and keeping its shape in the course. The invention has high purity, remarkable quality, few requirements for technical condition, without pollution and has low cost.

A cabinet-type electric connector consists of a plug and a socket; the plug and a shell of the socket are provided with a plurality of cavities for mounting a plurality of corresponding functional modules; and the abutting end of each functional module is provided with a mobile electromagnetic shielding device and a guide positioning device, wherein the mobile electromagnetic shielding device consists of a shielding plate, an elastic shielding reed, an insulating sleeve and a spring. By using a matching form of the mobile shielding plate and the elastic shielding reed, the electromagnetic shielding function after the connector is plugged and separated is well implemented; meanwhile, the arranged guide positioning device can well implement guiding and positioning when the plug is plugged in the socket so as to realize automatic alignment of the connector; and the cabinet-type electric connector has higher mounting error compensation capability, meets the requirements of cabinet-type application occasions, and has stronger practicability.

The invention provides an interior base station system which is a distributed base station system and mainly comprises a base band module and a radio frequency module. The base band module and the radio frequency module which are arranged independently are remote connected. The base band module is used for transceiving and processing base band signals and is connected with a base station controller; the radio frequency module is used for receiving and processing radio frequency signals. Obviously, by utilizing the existing cable network construction, the invention can facilitate interior full dimensional cover of the wireless networks; furthermore, the invention can realize the full dimensional cover of wireless communication networks without changing any parts of buildings. Therefore, the realization of the invention can effectively solve capacity and deep cover of the interior cover and greatly reduce network-building cost of the interior cover.

The invention discloses a lead-free relaxation antiferroelectric ceramic energy storage material, and a preparation method thereof. The chemical formula is (1-x-y)(Na<0.5>Bi<0.5>)TiO<3-x>(Sr<0.7>Bi<0.2>)TiO<3-y>Me<2>O<3>, wherein Me is used for representing one or two elements selected from La, Sm, and Dy, x and y are used for representing molar fractions, 0.2<=x<=0.7, and 0.01<=y<=0.2. The lead-free relaxation antiferroelectric ceramic energy storage material is relatively in energy storage density, energy storage efficiency, and possesses relaxation characteristics, and the preparation method is simple.

An indoor base station system that is a distribution base-station system mainly includes: the base-band module and the radio-frequency module, the self-setting base-band module and radio-frequency module are long connection, the base-band module use for dispatcher processing of the base-band signal and connect with the base-band controller, the radio-frequency module use for dispatcher processing of the radio-frequency signal. The invention may realize the omnidirectional covering indoor, do not change any part of the building. Therefore, the realization of the invention, has effectively solved the capacity and in-depth covering question of the indoor covering, also greatly reduces the net cost of indoor covering.

The present invention discloses data transmission method and equipment with synergetic hetero buses. The method has key data transmitted via MTL-STL-1553B bus and common data transmitted via IEEE1394 bus. The equipment includes CPU, MTL-STL-1553B bus interface chip, via IEEE1394 bus interface chip, program memory and data memory, connected via self-defined bus. The data transmission equipment of the present invention has both high reliability MTL-STL-1553B interface and high transmission rate IEEE1394 interface, and can realize high speed real-time data transmission and reliable network control and monitoring. At the same time, two kinds of buses back up mutually to ensure the normal and effective communication in the network.

The invention belongs to the field of indoor map construction, and provides an indoor SLAM mapping method and system based on semantic information fusion. The indoor SLAM mapping method based on semantic information fusion comprises the following steps: constructing an indoor environment planar grid map based on laser radar information; acquiring three-dimensional point cloud information of an indoor environment and category semantic tags, spatial positions and sizes of objects existing in the indoor environment, and calculating three-dimensional bounding boxes of all space objects; and projecting the bounding boxes of all the space objects to the planar grid map to construct an indoor SLAM semantic map.

The invention discloses a ceramic coating diaphragm, a preparation method thereof and an application, and relates to a lithium-ion battery separator. The ceramic coating diaphragm comprises a polymer diaphragm; one side or both sides of the polymer diaphragm is / are coated with a high heat conduction insulation nano-material. The high heat conduction insulation nano-material adopts a BN nano-wire, a BN nano-particle, and a BN nano-tube, and others; the preparation method includes steps of adding high heat conduction insulation nano-material in the polymer solution, and then coating to the polymer diaphragm; after volatilizing the solvent, acquiring the solid polymer membrane, namely, ceramic coating diaphragm. The ceramic coating diaphragm can be applied to the lithium ion secondary battery. The prepared ceramic diaphragm with high heat conductivity can be used as the ceramic coating diaphragm of the lithium ion secondary battery, thereby improving the safety performance of the lithium ion battery; the ceramic coating diaphragm has very good ionic conductivity and mechanical performance. The operability is strong.

The invention relates to a convertible walking mechanism of a robot, solving defects existing in a single walking mechanism, wherein each transmission chain part is controlled through the adoption of concentric shafts; each transmission interior shaft is directly connected with a track driving wheel in a track type structure and a wheel in a wheel type structure through flat keys; each track covers the track driving wheel and a track guide wheel; the track driving wheel and the track guide wheel covered by each track are fixedly arranged in each track bracket; each transmission exterior shaft is fixedly connected with the track bracket through screws, so that the swing of each track type structure is realized; and a track auxiliary wheel in each track type structure is fixedly arranged on a track auxiliary wheel supporting frame and connected in series with a motor together with two connecting bars through dowels for the formation of a four-bar mechanism group. The convertible walking mechanism of the robot is simple in mechanical structure, high in transmission efficiency and strong in adaptation ability, and can be applicable for various-condition road surfaces; and therefore, the application prospect is wide.

The invention relates to a magnetic material having high strain shape memory effect and process for making it, wherein the process for preparing comprises, melting the weighed material, preparing magnetic material using the conventional fast quench method with the preparation condition being, heating NiFeGa raw material to molten state, under the molten environment, ejecting argon of 1.0-1.50 barometric pressure to the copper wheel surface rotating at thread speed of 1-50 m / s, realizing 5-2000 m / s quick cooling down and acquiring fast quench thin belts. The starting temperature of the martensitic phase transformation of the material can be chosen to be in the range of between 120K-350K according to the need or the application. The material possesses better tenacity because of its iron content.

The invention relates to a stroke type interacting method for dividing a 3 d mesh model in real time. The method comprises: executing dividing operations to the 3 d mesh model through an audio-visual stoke interactive interface by users, firstly, using the characteristic perception scale on the basis of angles to obtain the discrete differential geometry characteristics, adopting a diffusion algorithm to carry out the dividing operations to the 3 d mesh model, and then using two rapid boundary adjusting algorisms with unchangeable topology and unchangeable geometry to generate a natural gridding dividing boundary on the basis of convex hull characteristics and the apparent angle characteristics respectively. Users can easily divide the 3D model without much time or technique. The invention provides two characteristic perception scales to divide models, the scales have clear physical meaning and can reflect the discrete differential geometry characteristics, and furthermore two rapid boundary adjusting algorisms with unchangeable topology and unchangeable geometry are respectively provided on the basis of the convex hull characteristics and the apparent angle characteristics. Compared with a dividing method of the prior art, the method can easily realize multi-stage division in one interaction.

The invention provides a serum-free culture medium system for culture of primary human epidermic cells, relates to the technical field of biological medical materials, and discloses application of a serum-free culture medium in in-vitro culture of human epidermic cells. The serum-free culture medium system has the advantage that the cholera toxin and various anchoring factors are not added, the potential hidden hazard due to complicated components is avoided, the epidermic cells can well grow, and the requirement of scaled production and application is met. The serum-free culture medium system for culture of primary human epidermic cells comprises a basic culture medium and exogenous adding factors, wherein the basic culture medium is formed by mixing a DMEM (dulbecco's modified eagle medium) commercial culture medium and a F12 commercial culture medium according to a certain ratio, and can also adopt a commercialized cell culture medium MCDB153; the exogenous adding factors comprise L-glutamine, EGF (epidermic growth factors), BPE (bovine pituitary extract), insulin, penicillin-streptomycin, calcium chloride, transferrin, adenine, hydrocortisone, and sodium selenite.

The invention discloses an electrolyte solution capable of improving over-charge safety performance of a lithium battery, which comprises following four types of components: (A) lithium salt, (B) organic solvent of carbonic esters and / or ethers, (C) over-charge safety additive and (D) other functional additives, wherein the composition of the solution can be written into A+B+C+D; the molar concentration range of the (A) lithium salt in the electrolyte solution is 0.001-2 mole / L; the mass ratio range of the (C) over-charge additive in the electrolyte solution is 0.01-30%, the molar concentration range of the (D) other functional additives in the electrolyte solution is 0-0.5 mole / L. The electrolyte solution can be applied to a lithium primary battery, a lithium secondary battery and a lithium ion battery.

The invention provides a satellite-borne CAN (controller area network) bus plug and play method. According to the method, equipment accessed into a CAN bus network automatically sends registration information requests, a satellite center computer actively obtains the registration information of the access equipment, the CAN bus of each equipment is dynamically configured according to the registration information of the access equipment, the software of the satellite center computer is rebuilt according to the registration information of the access equipment, and the rebuilt satellite center computer carries out normal bus communication with each equipment after the re-configuration. A system adopts the CAN bus to be used as a communication network, through the modification on a protocol, the equipment with an CAN bus interface can meet the plug and play use method, the adaptation to different satellite models can be realized without changing software and hardware, and the parallel development or advanced development of the satellite-borne equipment relative to the satellite general scheme is convenient.

The invention provides a preparation method of FeSe nano powder. The method comprises the following steps: 1, adding Se powder to an alkali liquor according to a certain molar ratio and agitating for dissolving, so as to obtain a solution A; 2, adding NaBH4 powder to the solution A according to a certain molar ratio and agitating for dissolving, so as to obtain a solution B; 3, adding a ferrous salt to the solution B according to a certain molar ratio in a glove box full of inert gases and agitating, so as to obtain a solution C; 4, adjusting the pH value of the solution C, and then orderly settling, filtering, washing and drying, so as to obtain the FeSe nano powder. The preparation method of the FeSe nano powder is simple and easy-to-control in preparation technology, short in technological process, strong in repeatability and applicable to industrial large-scale production. The FeSe prepared by the preparation method is tetragonal nanoscale powder, the chemical components and particle size distribution are even, and the requirements of subsequent application can be met.

The invention provides a method for establishing a three-dimensional tissue in vitro. The method comprises the steps of separately culturing epithelial cells and muscle cells; implanting a small intestinal submucosa acellular matrix stent into a muscle cell suspension; continuing to culture after finishing oscillating and compounding operations; and dropwise adding an epithelial cell suspension on a muscle cell layer of the stent treated in the step 2, and continuing to culture to obtain the three-dimensional tissue. According to the method, the epithelial cells and the muscle cells of tongue mucosa are used as seed cells, so that materials are conveniently obtained, the cells can be increased to the relatively high quantity within relatively short time, and therefore, the application requirement is met; the muscle cells are compounded with the small intestinal submucosa acellular matrix stent by using an oscillating method, so that a plurality of muscle cells can be soaked into the stent and can be relatively uniformly distributed; meanwhile, the stent can be loosened as much as possible on the premise that the stent is not obviously damaged, so that nutrient permeation and neovascularization can be favorably realized; and the three-dimensional tissue which can be used for tissue engineering urethra can be established.

The invention discloses an average current control circuit and an average current control method. In the circuit, one input terminal of an average current detection module is connected to a reference voltage signal output terminal of a band gap reference source, and another input terminal is connected to a source terminal of a power switch. A voltage transmission signal output terminal of the average current detection module is connected to an input terminal of a current regulator. Another input terminal of the current regulator is connected to the reference voltage signal output terminal of the band gap reference source, and an output terminal is connected to a negative input terminal of a comparator. An oblique wave generator input terminal is connected to the source terminal of the power switch, and an output terminal is connected to a positive input terminal of the comparator. An input terminal of a logic and driving circuit is connected to an output terminal of the comparator, another input terminal is connected to a switch starting pulse output terminal of an oscillator and an output terminal is connected to a grid terminal of the power switch. The source terminal of the power switch is connected to a grounding terminal via a detection resistor and a drain electrode is connected to a switch power supply module. Constant current precision is high, a current ripple wave is small and anti-noise performance is superior.

The invention discloses a method for testing sea sound field phase velocity by hydrophone, which comprising the following steps of: picking up normal-modes from the emission signals received by two hydrophones arranged along the spreading direction; carrying out 800-1000Hz band filtering and cross correlation calculation on No. 1 normal-mode received by the two hydrophones to obtain the time delay corresponding to the enveloping maximum point of cross correlation curve and multiplying the time delay by the a reference sound velocity to obtain an estimated distance between the two hydrophones; carrying out narrow-band filtering and cross correlation calculation on the normal modes of the same number to obtain the time delay of cross correlation which is the phase delay, the time delay of the enveloping maximum point of cross correlation which is the envelope delay and the phase velocity corresponding to the normal mode at the central frequency is equal to the phase delay at the estimated distance. The invention has the advantages that hydrophones are convenient to arrange on the same water level in the seabed; except sound speed of sea water, other sound field parameters are not necessary to foresee, thereby simplifying work amount and the test results are of high precision.

The invention provides a dealkalization and purification method used in the production of precipitated calcium carbonate. The method comprises the following successive steps: (1) adding water into a calcium carbonate system produced by causticization of white mud to obtain a calcium carbonate emulsion with solid content of 5 to 45 wt%; (2) adding a dealkalization agent with a mass concentration of 0.1 to 10% into the calcium carbonate emulsion and carrying out reaction and stirring so as to prepare mixed liquor; (3) delivering the mixed liquor prepared in the step (2) to a hermetically sealed upflow-type reaction vessel and carrying out reaction and stirring; and (4) after completion of the reaction, delivering the mixed liquor into a solid-liquid separator, diluting and washing the mixed liquor with water and then carrying out granularity control; wherein the dealkalization agent used in the step (2) is one selected from the group consisting of citric acid, formic acid or malic acid. The method can stabilize the pH value of the calcium carbonate system and improve product brightness and purity.