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154results about How to "Overcome size" patented technology

Experimental method of simulating dynamic and static load and device thereof

The invention discloses an experimental method of simulating dynamic and static load and a device thereof, relating to indoor model experimental technique of geotechnical engineering. The structure of the device is as follows: a model experimental platform (1), a model experimental box (2) and a load transmitting lever (3) are sequentially connected; the load transmitting lever (3) is respectively connected with a static load system (4) and a dynamic load system (5) which are respectively connected with a dynamic signal testing system (6); the dynamic signal testing system (6), a data acquisition system (7) and a computer (8) are sequentially connected. The device caries out dynamic and static load experiments on different structure models, and can monitor and collect non-linear properties of deformation and stress of gneiss under complex load condition in real time. The device has intuitional testing principle, simple structure, high precision, good stability, easy operation, convenient detachment and no high technical requirement to mounting and testing workers.
Owner:INST OF ROCK AND SOIL MECHANICS - CHINESE ACAD OF SCI

Multifunctional integrated type soil body freezing and thawing test system

The invention relates to a multifunctional integrated type soil body freezing and thawing test system which comprises five parts including a model bearing system, a temperature controlling system, a water replenishing system, an atmospheric environment simulation system and a data acquisition system. Temperatures of an upper temperature controlling plate and a lower temperature controlling plate in a model box are respectively controlled by a cold bath, a fan and a rotatable sprinkler head are arranged at the top of a box body, and thus simulation of atmosphere rainfall and field wind is realized. the water replenishing system is arranged at the bottom of the box body, a soil sample test section is provided with a temperature sensor, a volume unfrozen-water content sensor, a soil water potential sensor, a heat flux sensor, a deformation sensor and the like, which are used for effectively testing physical mechanical factors such as temperature, volume unfrozen-water content, soil water potential, a heat flux and deformation of a soil sample in a freeze-thawing process, thus measurement precision and range are greatly improved. The defect and the deficiency of size effect caused by small size of an existing freezing-thawing test system are overcome. The multifunctional integrated type soil body freezing and thawing test system is simple in structure, easy to operate, accurate in measurement, low in requirement of a working environment condition, and stable to work.
Owner:NORTHWEST INST OF ECO-ENVIRONMENT & RESOURCES CAS

Method for preparing nanometer aluminum or nanometer aluminum coating in low-temperature electro-deposition form by using ion liquid/additive system

The invention designs a method for preparing nanometer aluminum or nanometer aluminum coating in an electro-deposition form by using an ion liquid / additive system. The method is characterized in that: ion liquid and anhydrous aluminum trichloride are mixed into a low-temperature electrolyte and suitable additives are added for preparing the ion liquid / additive system. A processed substrate is taken as a deposition cathode; the direct current electro-deposition is adopted for preparing the nanometer aluminum or nanometer aluminum coating; and the size of the aluminum grains is adjusted according to requirements. According to the method, the problems of high cost and small output of the present technology for producing the nanometer aluminum are solved; the adopted ion liquid is conventional ion liquid and is characterized by wide source, low cost, high conductivity, wide electrochemical window and being non-volatile and environment-friendly; the suitable additives are used, so that the high-quality nanometer aluminum or nanometer aluminum coating obtained in the conventional ion liquid is realized; the obtained aluminum deposited coating is compact, smooth and flat; a nanometer material can be obtained by using the ion liquid / additive system at lower temperature; the reaction is easy to control; the energy consumption is low; the obtained nanometer aluminum is high in quality and high in current efficiency; the size of the nanometer aluminum can be effectively controlled by adjusting the dosage and formula of the additives; the process is simple; the cost is low; and the application prospect is better.
Owner:INST OF PROCESS ENG CHINESE ACAD OF SCI

Preparing method for aluminum-based nano composite material

The invention relates to a preparing method for an aluminum-based nano composite material. An in-situ synthesis method is adopted to generate enhanced body particles in aluminum melt, and after alloyelements are added, aluminum-based nano composite material melt is manufactured; an aluminum-based nano composite material ingot blank is manufactured through the aluminum-based nano composite material melt via the rapid solidification jetting deposition technology; and then, the hot isostatic pressing technology is adopted for conducting densifying treatment on the aluminum-based nano composite material ingot blank, and the aluminum-based nano composite material is obtained after heat treatment of the ingot blank. The aluminum-based nano composite material prepared through the preparing method has the characters that enhanced body components are uniform, base body grains are fine, and the interface bonding strength is high, and the aluminum-based nano composite material can be applied tothe fields of aerospace, transportation, electronic devices, the sport industry and the like; and meanwhile, in-situ synthesis and rapid setting are integrally formed, efficient manufacturing of the aluminum-based nano composite material is achieved, and the preparing method is suitable for industry production.
Owner:CENT SOUTH UNIV

Laser 3D printing method of amorphous alloy composite material

The present invention discloses a laser 3D printing method of an amorphous alloy composite material. Amorphous alloy composite material alloy powder whose grain size is 20-150 [mu]m is formed into amorphous alloy composite material components through a coaxial powder feeding 3D printing method under the conditions that the laser power is 100-600 W, the scanning speed is 500-1200 mm / min, the laser spot diameter is 0.5-4 mm, the overlap rate is 15-50%, the printing layer thickness is 0.5-2 mm, the printing environment oxygen concentration is lower than 50 ppm, and the substrate preheating temperature is 0-300 DEG C. The amorphous alloy composite material components are annealed for 2-12 hours under the protection of an inert gas and at a temperature of 300-600 DEG C. With adoption of the laser 3D printing method, defects of the amorphous alloy composite material formed through a water quenching method and a copper mold casting method are overcome, the problem that the amorphous alloy composite material is hard to mechanically process is solved, and the method has the advantages of being economical in raw material and high in efficiency.
Owner:DALIAN JIAOTONG UNIVERSITY

Method for preparing black phosphorus nanosheets

The invention discloses a method for preparing black phosphorus nanosheets. The method comprises the following steps: (1) assembling black phosphorus used as an electrode and an organic solvent containing an intercalating agent, used as an electrolyte, in order to form an H-shaped electrolytic cell; (2) applying a current or voltage between the electrodes to intercalate and expand the black phosphorus; (3) filtering and washing the treated black phosphorus obtained in step (2), and carrying out ultrasonic vibration treatment on the treated black phosphorus in an organic solvent; and (4) centrifuging the obtained solution, and collecting the obtained supernatant to obtain a uniform-size black phosphorus nanosheet dispersion. The black phosphorus nanosheets stripped by the method have a thickness of 2-100 nm and a lateral dimension of 10 nm to 50 [mu]m. The method solves the problem of difficult control of the thickness and the lateral dimension of the black phosphorus nanosheets duringthe preparation of the black phosphorus nanosheets in the prior art, also solves the problem of too long time in traditional black phosphorus nanosheet preparation methods, and has the advantages of simple preparation process, low energy consumption, low cost, and realization of large-scale production.
Owner:深圳市中科墨磷科技有限公司

Machine vision-based strawberry appearance quality judgment method

The invention discloses a machine vision-based strawberry appearance quality judgment method. The method specifically comprises the following steps of 1: establishing a three-camera vision platform and then all-directionally acquiring strawberry RGB images in an industrial scene; 2: performing image segmentation by utilizing the acquired images in the step 1, then defining fruit regions of interest, and extracting strawberry fruit contours; 3: extracting shape feature vectors of strawberries by using a shape invariant feature extraction operator through utilizing the extracted strawberry fruit contours in the step 2, thereby overcoming the problems of different sizes, positions and orientations of the strawberries; and 4: training a support vector machine by utilizing the acquired sample images of strawberries in different shapes in the step 1 and the extracted feature vectors in the steps 2 and 3, and determining optimal parameters and classification accuracy of the support vector machine. The invention provides a strawberry appearance quality judgment method with the characteristics of high accuracy, robustness, real-time property and no damage for the problems of low manual identification efficiency, high mechanical damage rate and the like, and actual usage requirements are met.
Owner:CHUZHOU UNIV

Fabrication of light emitting film coated fullerenes and their application for in-vivo light emission

A nanoparticle coated with a semiconducting material and a method for making the same. In one embodiment, the method comprises making a semiconductor coated nanoparticle comprising a layer of at least one semiconducting material covering at least a portion of at least one surface of a nanoparticle, comprising: (A) dispersing the nanoparticle under suitable conditions to provide a dispersed nanoparticle; and (B) depositing at least one semiconducting material under suitable conditions onto at least one surface of the dispersed nanoparticle to produce the semiconductor coated nanoparticle. In other embodiments, the nanoparticle comprises a fullerene. Further embodiments include the semiconducting material comprising CdS or CdSe.
Owner:RICE UNIV +1

Electron beam melting and laser milling composite 3D printing apparatus

The invention relates to the technical field of 3D printing apparatus and discloses an electron beam melting and laser milling composite 3D printing apparatus. The3D printing apparatus comprises a base on which a machining platform is arranged; a powder spreading structure for spreading a metal powder on the machining platform is arranged on the base; an electron beam emitting structure and a laser milling head are arranged above the machining platform, respectively; the electron beam emitting structure emits an electron beam to melt the metal powder layer so as to form a single-layer or multi-layer approximate body; the laser milling head emits a laser beam to perform milling machining on the single-layer or multi-layer approximate body. The 3D printing apparatus is integrated with the removal machining taking laser milling as the principal method and the incremental laminating manufacturing process with electron beam melting 3D printing as the principal method, and therefore, the defects of the 3D printing technology in the aspects such as size and shape are overcome, the restriction of cutting to the complexity of parts and the like is overcome, the machined parts do not need to be machined secondarily, and the problems of difficult clamping, large machining error, part deformation during machining and difficult machining are avoided.
Owner:YUANMENG PRECISION TECH SHENZHEN INST

Preparation method for visible light photocatalyst powder and cloth from bismuth-rich material

A preparation method for a visible light photocatalyst powder and cloth from a bismuth-rich material comprises the steps: dissolving the bismuth-rich material and dithiocarbamate in solvents respectively, and adding the dithiocarbamate solution to the bismuth-rich solution drop by drop to produce a precipitate; filtering, washing and drying, to obtain a metal element-doped bismuth dithiocarbamate;dissolving the prepared metal element-doped bismuth dithiocarbamate in a good solvent, adding macromolecules, carrying out electrostatic spinning, and thus obtaining the cloth with a photocatalytic function. The prepared metal element-doped bismuth dithiocarbamate has the advantages of uniform morphology and size, good dispersibility, green and environmental protection, stability in air, water and most solvents, acid and alkali resistance, industrial mass production potential, and excellent photocatalytic pollutant degradation activity, and realizes the direct conversion and reuse of the bismuth-rich material; the photocatalytic cloth can effectively prevent the diffusion of the catalyst powder and realizes the effective recycling of the photocatalyst.
Owner:XI AN JIAOTONG UNIV

Prefabricated assembly FRP-reinforcing steel-bar-concrete combined bridge deck and construction method

The invention discloses a prefabricated assembly FRP-reinforcing steel-bar-concrete combined bridge deck and a construction method. The prefabricated assembly FRP-reinforcing steel-bar-concrete combined bridge deck comprises a semiclosed FRP groove and concrete inside the FRP groove, wherein the bottom surface and two side surfaces of the concrete are wrapped by the FRP groove to form the combined panel, a transverse through reinforcing steel bar reserved tunnel is formed in a transverse setting position of the combined panel, a transverse prestress reinforcing steel bar is arranged in the reinforcing steel bar reserved tunnel to connect a plurality of FRP-concrete combined panel prefabricated components to form an integral bridge panel structure in a needed size. The construction method comprises the steps: firstly producing the semiclosed FRP groove; arranging an FRP rib and an embedded corrugated pipe, and fixing the FRP rib and the embedded corrugated pipe; pouring concrete; splicing a plurality of prefabricated FRP-concrete combined deck components into a whole by utilizing the prestress after the strength of the concrete reaches the requirement. The factorization prefabrication and on-situ assembling of the FRP combined bridge deck are realized, the structure is simple, and the construction is convenient.
Owner:SHANDONG UNIV

Mechanical processing positioning device

The invention disclose a mechanical processing positioning device, which comprises a base (1), an adjusting support assembly and an adjustable clamping mechanism, wherein the adjusting support assembly comprises a cylindrical taper pin (5), a compression spring A (6) and a screw plug (7), the cylindrical taper pin (5) is arranged in an inner cavity (2), the adjustable clamping mechanism comprises an adjusting screw rod (10), a press plate (11) and a compression spring B (12), the press plate (11) and the compression spring B (12) are sheathed outside the adjusting screw rod (10), and the adjusting screw rod (10) penetrates through a through hole (3) arranged on the base (1) and is fixed by a locking screw bolt (16). The mechanical processing positioning device has the beneficial effects that the diameter of the large end of a cone front part (8) is greater than the diameter of a blank hole, the wider positioning range is realized, the cylindrical taper pin (5) is tightly matched with the blank hole by the adjusting support assembly via the extension and retraction of the compression spring A (6), the influence of size and roundness errors of the blank hole can be overcome, the matching clearance is eliminated, and the positioning error is greatly reduced.
Owner:成都恒高机械电子有限公司

Transmission-type terahertz spectral analysis method independent of reference light

The invention discloses a transmission-type terahertz spectral analysis method independent of reference light, which comprises the following steps of: (1) performing transmission-type spectral measurement on a tested sample to obtain a terahertz time domain wave form of the tested sample; (2) obtaining a phase spectrum of the tested sample in a system effective frequency range according to the measured terahertz time domain wave form; and (3) extracting a characteristic absorption spectrum of the tested sample in a terahertz wave range from the phase spectrum.
Owner:CAPITAL NORMAL UNIVERSITY

Digital-image-based method for determining permeability coefficient of nonuniform geotechnical material

InactiveCN104268830AOvercome sizeOvercome shortcomings such as inconsistency with on-site conditionsImage enhancementOsmotic coefficientMaterial resources
The invention discloses a digital-image-based method for determining the permeability coefficient of a nonuniform geotechnical material. Firstly, denoising and binarization processing are performed on an acquired colored digital image so that a binary image showing rock and other components can be obtained, then, the drawing boundaries in the image are extracted and converted into a vectorgraph file, finally, permeability analysis is performed based on finite element meshes in the vectorgraph file through a numerical value simulation test, and the permeability coefficient is determined. Compared with the prior art, the method overcomes the defects in a traditional laboratory test for evaluating the permeability coefficient, for instance, the test result is greatly influenced by samples, the test dimension of the laboratory test is different from that of a site test, and the defect that a large amount of manpower and a large number of material resources are consumed in a traditional on-site in-situ test is also overcome. The digital image technology is introduced to the method, the method has the advantages of being high in efficiency, low in cost and the like, and the permeability coefficient of a large-size nonuniform geotechnical material can be analyzed.
Owner:HOHAI UNIV

Millimeter-wave dual-frequency Doherty power amplifier based on single frequency line

The invention provides a millimeter-wave dual-frequency Doherty power amplifier based on a single frequency line. The millimeter-wave dual-frequency Doherty power comprises a dual-frequency power divider, a primary power amplifier dual-frequency input matching network, a secondary power amplifier dual-frequency input matching network, a primary power amplifier tube, a secondary power amplifier tube, a primary power amplifier dual-frequency output matching network, a secondary power amplifier dual-frequency output matching network, and a dual-frequency post matching network, wherein the dual-frequency power divider is connected with the primary power amplifier dual-frequency input matching network through a first single-frequency transmission line of a first preset length; the primary power amplifier dual-frequency output matching network is connected with the dual-frequency post matching network through a second single-frequency transmission line of a second preset length; and the secondary power amplifier dual-frequency output matching network is connected with the dual-frequency post matching network through a third single-frequency transmission line of a third preset length. Through adoption of the millimeter-wave dual-frequency Doherty power amplifier, a dual-frequency phase shift function is realized by an ordinary single-frequency transmission line, so that the problems of large size, great loss and small bandwidth in a conventional dual-frequency transmission line on a millimeter-wave band are solved, and the performance of a dual-frequency phase shift line can be enhanced greatly.
Owner:TSINGHUA UNIV

AFU antenna and filter thereof

The invention relates to an AFU (Antenna-Filter Unified) antenna and a filter thereof. Radio frequency ports of the antenna are moved from a coupling PCB to filters, and the filters are arranged in two columns on a PCB of a coupling calibration network in a mirroring manner. The area of the PCB is reduced without changing the relative positions of the radio frequency ports of the AFU. A resonanceplate and one side of a cavity of each filter are integrally formed, which reduces the assembly difficulty. A low-pass assembly adopts a PCB micro-strip line, and has high precision and a diversifiedstructure.
Owner:TONGYU COMM INC

Preparation method of magnesium hydrate

InactiveCN102849761AOvercome sizeOvercome the defect of prone to reunionMagnesium hydroxideAlkaline earth metalMagnesium salt
The invention provides a preparation method of magnesium hydrate, and relates to the technical field of magnesium hydrate. The preparation method comprises the following steps of: preparing a raw material magnesium salt solution by magnesium chloride or magnesium sulfate separated out of salt mine or sea salt, adding a mixed aqueous alkali precipitator prepared by the ammonia water, the alkali metal hydroxide or the alkaline-earth metal hydroxide to generate precipitate of magnesium hydrate, filtering, washing, thermally modifying water, aging in a cooling way, filtering, washing and drying to obtain a magnesium hydrate product of which the grain size is 0.5-5.0mu m and the purity is larger than 97%, and treating and recovering the filter liquor in the process to obtain ammonia water, preparing the mixed aqueous alkali to be recycled by the recycled ammonia water, the alkali metal hydroxide or the alkaline-earth metal hydroxide according to the proportion by the mass percent such as (4-9): 1, so that the mixed bases can be recycled, therefore, various defects of the existing chemical precipitation method can be overcome, and the high-purity and low-granularity magnesium hydrate product can be prepared at low production cost.
Owner:HEBEI UNIV OF TECH

Temperature sensor preparation method based on carbon nano tube three-dimensional network film

The invention discloses a temperature sensor preparation method based on a carbon nano tube three-dimensional network film. The temperature sensor preparation method mainly solves the problems that the method which takes a carbon nano tube conduction network in a polymer as a temperature sensor has the disadvantages of big forming difficulty of composite material, integral mechanical property affection and high cost. The temperature sensor preparation method comprises the following realization steps of: a) preparing monodisperse aqueous solution of the carbon nano tube by the carbon nano tube and surface dispersant mixture with a mechanical fusion method; b) pouring the monodisperse aqueous solution of the carbon nano tube into an upper container of a vacuum suction filtration device, and carrying out suction filtration to form a film on a filtering film; c) putting a carbon nano film and the filtering film into a drying oven, and stripping the filtering film to obtain a three-dimensional film after solidification is finished; and d) cutting a rectangular structure from the film, fixing a copper conductor onto the surface of the carbon nano tube film by conductive adhesive, embedding the sensor into the composite material, or externally pasting the sensor on the external specific position of the composite material, and forming according to the composite material solidification technology. The resistivity of the carbon nano tube three-dimensional film temperature sensor can be 10<-3>-10<-5>omega.m, and the carbon nano tube three-dimensional film temperature sensor has a higher resistance-temperature linear relation.
Owner:SHENYANG AEROSPACE UNIVERSITY

Multi-electron-beam fusing and milling composite 3D printing device

The invention relates to the technical field of 3D printing devices, and discloses a multi-electron-beam fusing and milling composite 3D printing device which comprises a base. A machining platform is arranged on the base which is provided with a powder laying structure. A plurality of electron beam transmitting structures and milling heads are arranged on the machining platform. The electron beam transmitting structures are arranged outside the milling heads in a surrounding mode at intervals and transmit electron beams to fuse different areas of a metal powder layer so as to form a plurality of single-layer or multi-layer approximate bodies. The milling heads mill the single-layer or multi-layer approximate bodies respectively. By means of the 3D printing device, the removal type machining process with laser milling as the main part and the incremental laminated manufacturing process with electron beam fusing 3D printing as the main part are integrated, and the deflects of the size and shape of the 3D printing technology are overcome; for large-size parts, the electron beams fuse different areas, milling is then conducted through the milling heads, and parts can be formed in any large sizes.
Owner:YUANMENG PRECISION TECH SHENZHEN INST

Preparation method of visible-light response nano La/Ni-SrTiO3

The invention provides a preparation method of visible-light response nano La / Ni-SrTiO3. The method includes the following steps that firstly, an aqueous solution containing strontium nitrate, lanthanum nitrate and nickel nitrate is mixed with a citric acid aqueous solution, and a solution A is obtained; butyl titanate is dissolved in ethylene glycol to obtain a solution B; secondly, the solution B is dropped in the solution A at a constant speed, and sol is obtained; thirdly, the sol is heated and stirred, and wet gel is obtained; fourthly, a potassium hydroxide solution with the concentration being 5 mol / L is added into the wet gel, and a mixture is obtained; fifthly, the mixture is contained in a high-pressure kettle, and heat preservation is performed for 20-24 h at the temperature of 200 DEG C; sixthly, obtained matter is dried after being washed, and nano La / Ni-SrTiO3 is obtained. Elements can be well added into SrTiO3 through a sol-gel hydrothermal method, and an obtained sample has remarkable responses on visible light. The method is simple in preparation technology, low in cost and high in yield, the diameter of the obtained product reaches nano scale, and the obtained product is evenly distributed.
Owner:HEBEI UNIV OF TECH

Preparation method of narrow graphene nanoribbons

A method for making a strip shaped graphene layer includes the following steps. First, a graphene film is located on a surface of a substrate is provided. Second, a carbon nanotube structure is disposed on the graphene film. The carbon nanotube structure includes a plurality of carbon nanotube segments and a plurality of strip-shaped gaps between the adjacent carbon nanotube segments. Third, the graphene film exposed by the strip-shaped gaps is removed by a reactive ion etching method.
Owner:TSINGHUA UNIV +1

Preparation method of piezoelectric ceramic spherical shell

The invention relates to a preparation method of a piezoelectric ceramic spherical shell. The method comprises the steps that: (1) ceramic powder, a dispersant, a curing agent system, and water are sufficiently mixed, such that high-solid-content and low-viscosity ceramic slurry is obtained; (2) a wax material is heated and melted; the molten wax material is filled into a first hollow spherical mold, such that a wax solid ball is formed; (3) the wax solid ball formed in the step (2) is concentrically arranged in a second hollow spherical mold, wherein the diameter of the second hollow spherical mold is larger by 0.2-2cm than that of the wax solid ball, such that a spherical gap is formed; the ceramic slurry is filled into the spherical gap; a gel reaction is initiated, such that the ceramic slurry is solidified into a spherical shell structure; the material is heated, and the wax ball is molten and flows out; and de-molding is carried out; and (4) the hollow ceramic spherical shell blank is heated to a temperature of 550 DEG C; the temperature is maintained for 2h; the ceramic spherical shell blank is sintered, such that the piezoelectric ceramic spherical shell is prepared. The method provided by the invention is advantaged in that no additional pressure is needed, and the operation is simple and feasible.
Owner:INST OF ACOUSTICS CHINESE ACAD OF SCI

Tissue engineering stent based on low-temperature rapid modeling and preparation method thereof

ActiveCN106668948AOvercome sizeOvercome the defects that are too small (<100μm)Tissue regenerationCoatingsBiomechanicsMass ratio
The invention relates to a tissue engineering stent based on low-temperature rapid modeling and a preparation method thereof. The preparation method comprises the following steps: mixing a polylactic acid-glycolic acid copolymer and an organic solvent in a mass ratio of 1: 6 to 1: 8 to prepare a PLGA (polylactic acid-glycolic acid) solution, and adding sodium chloride granules to obtain a printing slurry, wherein the mass ratio of the sodium chloride granules to the PLGA is 1: 2 to 2: 1; setting the fiber diameter to be 200-300 microns, setting the fiber spacing to be 300-350 microns, printing out a stent body containing the sodium chloride granules at a speed of 3-6mm / s, and removing the organic solvent and the sodium chloride to obtain the tissue engineering stent based on the low-temperature rapid modeling. According to the invention, through addition of an excipient, low-temperature printing of a PLGA material is achieved, and the defect of a too large or too small aperture size caused by high-temperature fused printing of a PLGA stent is overcome; the prepared PLGA stent is moderate in aperture size, can easily store cells, and has good biomechanical properties.
Owner:杭州弘新生物科技有限公司

Small-size circumferential-spiral-groove longitudinal-vibration underwater transducer

ActiveCN107509137AReduce vibration frequencySimple structure and manufacturing processTransducers for subaqueous useLongitudinal vibrationFront cover
The invention discloses a small-size circumferential-spiral-groove longitudinal-vibration underwater transducer, which comprises a transducer body. The transducer body comprises a back cover plate, a piezoelectric ceramic stack, a front cover plate and a front-end cutting body, which are connected in sequence. The piezoelectric ceramic stack is formed by piezoelectric ceramic pieces and electrode slices, which are laminated alternately, and the two ends of the piezoelectric ceramic stack are the electrode slices respectively. One end of each piezoelectric ceramic piece is connected to a positive lead wire through the corresponding electrode slice, and the other end thereof is connected to a negative lead wire through the corresponding electrode slice; and the positive lead wire and the negative lead wire are connected to an excitation source. The underwater transducer realizes low-frequency emission within a frequency range of 50 Hz-1000 Hz. Besides, the transducer has the advantages of small overall size, simple structure and manufacture process and low cost.
Owner:SHAANXI NORMAL UNIV

Miniaturized high-gain double-frequency WIFI antenna

The invention provides a miniaturized high-gain double-frequency WIFI antenna, which comprises a dielectric plate, a micro-strip feed network, a bonding pad, two symmetrical dipole radiation units, anasymmetric dipole radiation unit and u-shaped stubs. The micro-strip feed network comprises stepped micro-strip lines printed on the upper layer and the lower layer of the dielectric plate. Each dipole unit comprises two dipole arms printed on the upper layer and the lower layer of the dielectric plate, and each dipole arm is composed of a low-frequency radiation stub and a high-frequency radiation stub which respectively cover low-frequency and high-frequency bandwidths. The dipole units are positioned on the same side of the micro-strip feed network, so that miniaturization of the antenna is realized. The asymmetric dipole unit is connected with one symmetric dipole unit in parallel and then connected with the other symmetric dipole unit in series, so that the currents of the radiationunits of the antenna is in the same phase, and the gain of the antenna gain is increased. The u-shaped stubs play a role in adjusting the phase of the antenna. The technical problems of overlarge size, relatively low gain and relatively poor omnidirectivity of an antenna are solved.
Owner:XIDIAN UNIV

Light polyether-ether-ketone or composite material thereof with different degrees of crystallinity and preparation method thereof

The invention discloses light polyether-ether-ketone or a composite material thereof with different degrees of crystallinity thereof and a preparation method thereof and belongs to the technical field of preparation of high molecular materials. The preparation method comprises the following steps of: putting polyether-ether-ketone or the composite material thereof in a near critical or supercritical CO2 fluid, swelling and permeating the same at 320-360 DEG C and the saturated pressure of 5-30MPa for 30min to 3h, then quickly unloading to constant pressure and cooling to room temperature; and repeating the operations for 1-3 times and finally performing annealing treatment to obtain the light polyether-ether-ketone or the composite material thereof with different degrees of crystallinity, different bubble dimensions and high foaming rates. The preparation method disclosed by the invention overcomes defects that crystallized polyether-ether-ketone or the composite material thereof prepared in the prior art is small in foaming swelling rate, single in bubble dimension, hard to saturate gas and the like, expands the application field of polyether-ether-ketone, and improves the bottleneck of existing crystallized polyether-ether-ketone or the composite material thereof in the foaming technology.
Owner:SINO HIGH CHINA

Preparation method of micro-nano double-scale composite porous material

InactiveCN109652673AOvercoming extremely high brittlenessOvercoming technical bottlenecksDirectional solidificationSolid gas
The invention discloses a preparation method of a micro-nano double-scale composite porous material. The preparation method comprises the following steps that a micron-scale regular through hole material with a pore structure controllable and oriented arranged is obtained through a solid-gas eutectic directional solidification process; then the porous material is taken as a precursor, the porous material of the precursor is subjected to dealloying treatment through chemical corrosion or electrochemical corrosion, so that nano pores are formed between the directional micro-pore walls, micro pores are communicated, and finally three-dimensional continuous micro-nano double-scale pores are obtained. The micro-nano double-scale composite porous material prepared by the method not only overcomes the defects that a traditional dealloying nano porous material is extremely small in size and extremely high in brittleness, but also maintains or expands the specific surface area of the porous material, the structural characteristics of which are undoubtedly beneficial to the transmission of fluid and macromolecules, so that the material is expected to be applied to the fields of catalysis, sensing, fuel cells, micro-flow control and the like, and has an important application prospect.
Owner:KUNMING UNIV OF SCI & TECH
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