360 results about "Absorption frequency" patented technology

The invention provides a terahertz plane adsorbing material, belonging to the technical field of electromagnetic function materials and relating to an electromagnetic-wave absorbing material. The terahertz plane adsorbing material comprises a substrate, a metal reflecting layer, a dielectric layer and an artificial electromagnetic medium layer; wherein, the metal reflecting layer is a continuous metal film and is arranged on the surface of the substrate; the dielectric layer is arranged between the metal reflecting layer and the artificial electromagnetic medium layer; the artificial electromagnetic medium layer is composed of artificial electromagnetic medium units which are arrayed periodically, each unit is a centro-symmetric figure formed by metal film lines with line width which is t and comprises two sing-opening metal rings which are connected backwards with long edges at two sides of an electric snap ring resonator. The terahertz plane adsorbing material provided by the invention has two strong-absorption frequency ranges, so as to provide selective adsorption and detection at different frequency ranges, and the terahertz radiation with wider spectral range can be adsorbed, so as to improve the performance and efficiency of the terahertz plane adsorbing material.

The present invention provides a method and apparatus for non-invasive reduction of excessive fat tissue by externally applying radio frequency (RF) electromagnetic (EM) waves adjusted to specific fat cells absorption frequency and electromagnetic propagation mode. Based on the performed experiments described further, the method and working apparatus has been invented that reduces fat layers without any medication, non-invasively through the intact skin. The invented method and apparatus facilitates the safe fat removal, and may lead to reduction and eradication of obesity and obesity associated diseases.

Apparatus is provided for a method of forming a film on a substrate that includes activating a gas precursor to deposit a material on the substrate by irradiating the gas precursor with electromagnetic energy at a frequency tuned to an absorption frequency of the gas precursor. The electromagnetic energy can be provided by an array of lasers. The frequency of the laser beam is selected by switching from one laser in the array to another laser in the array. The laser array may include laser diodes, one or more tunable lasers, solid state lasers, or gas lasers. The frequency of the electromagnetic energy is selected to impart specific amounts of energy to a gas precursor at a specific frequency that provides point of use activation of the gas precursor.

The invention relates to a multiple helmholtz resonator parallel cellular sandwich wood sound absorption plate, belonging to the field of sound absorption technologies. The invention solves the problems of small chamber volume ratio, narrow sound absorption frequency band and poor sound absorption effect in the traditional sound absorption panels. Technical essential is characterized in that a sandwich layer is a cellular sandwich layer; the cellular sandwich layer is formed from splicing a plurality of cylinder bodies with hexagonal cross sections; an inner cavity of each hexagonal cylinder body is a cell cavity chamber; the chamber volume ratio of the sandwich layer is larger than 90%; the area of perforation shape surrounded by contour lines of each perforation is less than a half of the hexagonal area of corresponding sandwich layer; and each small through hole on a panel is communicated with the cell cavity chamber at the corresponding position of the sandwich layer. The invention has wider sound absorption frequency band and better medium high frequency sound absorption performance, and the sanding wave tube method sound absorption coefficients respectively reach 0.8, 0.9 and 0.7 at 500Hz, 1000Hz and 2000Hz. In addition, the invention also has the characteristics of light weight, high ratio of strength to weight, good decorative effect, and the like; and wood resources can be saved, preparation process is simple, and cost is low.

A graphene transistor optical detector based on a metamaterial structure and an application thereof. The optical detector includes a substrate, a gate metal layer, a gate medium layer, a graphene layer, a source and drain metal layer successively arranged from bottom to top, wherein a local region of at least the source and drain metal layer has a periodic micro/nanostructure, the periodic micro/nanostructure being matched with the gate metal layer and the gate medium layer to form a metamaterial structure having a complete absorption characteristic. By changing the refractive index, thickness or the like of material for the periodic micro/nanostructure and the gate medium layer, a light absorption frequency band of the metamaterial structure can be regulated. The optical detector provided by the present invention has higher flexibility and narrow-band response, and can work under visible light to infrared even longer wavebands by selecting different metamaterial structures.

The invention relates to a micro-perforated plate with a resonant sound absorption structure. The micro-perforated plate with the resonant sound absorption structure is characterized by comprising a rigid wall, a micro-perforated plate and a cavity which is formed between the rigid wall and the micro-perforated plate, wherein the two ends of the rigid wall are connected with the two ends of the micro-perforated plate through a flexible or elastic material respectively. In the sound wave absorption process of the micro-perforated plate with the resonant sound absorption structure, the distancebetween the micro-perforated plate and the rigid wall can be automatically adjusted and a semi-active resonant sound absorption structure is formed in the cavity between the micro-perforated plate and the rigid wall along with the variation of sound wave frequency and the influence of vibrating air flow. Therefore, the micro-perforated plate with the resonant sound absorption structure has highersound absorption performance in a wider frequency range, the sound absorption frequency band of the micro-perforated plate with the resonant sound absorption structure is greatly expanded, and the defect of a narrower sound absorption frequency band of a sound absorber of the micro-perforated plate with a rigid structure can be overcome. The micro-perforated plate with the resonant sound absorption structure can be widely used for the sound absorber, mufflers and various sound absorption and insulation structures to treat a noise environment caused by air power noise.

The invention relates to a graphene/polyaniline/cobalt composite wave-absorbing material and a preparation method thereof, belonging to the field of preparing an electromagnetic wave absorption material. The wave-absorbing material comprise a film forming material and an electromagnetic wave absorbent, wherein paraffin is adopted as the film forming material, a graphene/polyaniline/cobalt ternary complex is adopted as the electromagnetic wave absorbent, and the mass ratio of the graphene/polyaniline/cobalt ternary complex to the paraffin is 1:1. The preparation method of the material comprises the following steps: (1) preparing graphite oxide; (2) preparing the graphene/polyaniline binary complex; (3) preparing the graphene/polyaniline/cobalt ternary complex; (4) weighing graphene/polyaniline/cobalt ternary complex and paraffin, and evenly mixing to obtain a graphene/polyaniline/cobalt wave-absorbing material. The material has the characteristics of being low in cost, simple in preparation technology, strong in electromagnetic wave absorption capability, wide in absorption frequency band, small in density and the like, achieves good electromagnetic property and stability, and has important application values in the fields of microwave absorption and electromagnetic shielding.

A noise suppressor for an apparatus having a cooling fan and cooling duct includes a muffler including a reflection plate for reflecting sound from the cooling fan, the reflection plate being provided at a position in the cooling duct confronting the intake plane of the cooling fan and formed substantially parallel to the intake plane. A sound-absorbing part of the muffler is provided on the reflection plate, and a distance d between the reflection plate and the intake plane is set such that d<c/(2×f) where f is the sound-absorption frequency of the muffler and c is the speed of sound.

The invention discloses an expandable graphite/polyaniline/cobalt ferrite wave-absorbing material with an anti-electromagnetic interference function and a preparation technology thereof. The invention aims to provide an expandable graphite/polyaniline/cobalt ferrite wave-absorbing material which has strong electromagnetic wave absorbing capability and wide absorption frequency bandwidth and is convenient to use without causing environmental pollution and a preparation technology thereof. According to the invention, the wave-absorbing material consists of paraffin serving as a film forming material and an expandable graphite/polyaniline/cobalt ferrite ternary complex serving as an electromagnetic wave absorbent. The preparation technology of the expandable graphite/polyaniline/cobalt ferrite wave-absorbing material comprises the following steps of: (1) preparing expandable graphite; (2) preparing absolute ethyl alcohol containing expandable graphite; (3) preparing an expandable graphite/polyaniline binary complex; (4) preparing the expandable graphite/polyaniline/cobalt ferrite ternary complex; and (5) weighing the expandable graphite/polyaniline/cobalt ferrite ternary complex and the paraffin, uniformly mixing the expandable graphite/polyaniline/cobalt ferrite ternary complex and the paraffin and performing ball milling to obtain the expandable graphite/polyaniline/cobalt ferrite wave-absorbing material.

The invention provides a graphene and ferric oxide nanometer material and a preparation method for absorbing high-frequency electromagnetic waves. Add 0.08-0.12 grams of graphene to 280-320 milliliters of water to dissolve, then add 0.05-0.15 grams of Fe(NO3)3.9H2O to the solution to obtain a mixed solution, and stir the mixed solution for two hours at 50 degrees Celsius in a water bath, and then The obtained precipitate was separated by centrifugation, washed several times with ethanol and distilled water, and dried in a vacuum environment; the obtained product was heated to 350 degrees Celsius under argon for annealing for 2 hours, and after cooling to room temperature, graphene was obtained with Fe3O4 nanocomposites. The film prepared by using the material of the invention has an absorption intensity below -20dB when the thickness is 3-6mm, and the absorption intensity of microwaves with frequencies around 5.5GHz and 7GHz exceeds -30dB respectively. Moreover, its absorption frequency width is large, less materials are used, and the material of the film material produced is lighter, which is more conducive to industrial production and has wider applications.

The invention discloses a ferroferric oxide@carbon/reduced graphene oxide nano composite wave-absorbing material and a preparation method thereof. By using graphene oxide as a template, ferric chloride hexahydrate as a metal salt, terephthalic acid as an organic ligand, and N,N-dimethylformamide as a solvent, the ferroferric oxide@carbon/reduced graphene oxide nano composite material is prepared by a solvothermal-high temperature pyrolysis two-step method. The preparation method is environmentally friendly, generates no toxic by-products, and has a simple preparation process. The prepared nanocomposite material has a good microwave absorption capacity, a wide absorption frequency band, a low thickness, light weight and a low filling ratio, can absorb electromagnetic waves in different wavelength bands by adjusting the addition amount of graphene oxide in a precursor and the thickness of a coating layer, and has an important application value in the field of electromagnetic absorptionand electromagnetic shielding.

The invention discloses a terahertz wave detector and a manufacturing method of the terahertz wave detector. The terahertz wave detector is used for detecting radiation in the terahertz wave band and comprises a top layer composite sensitive thin film layer and a cross-shaped metamaterial metal hollow absorbing layer located below the top layer composite sensitive thin film layer. A cross-shaped hollow graph is centrally symmetric, and the cross-shaped metamaterial metal hollow absorbing layer generates intense resonance absorption in the specific terahertz wave band and has an obvious absorption peak. Due to the characteristics of the centrally symmetric cross-shaped hollow graph, the cross-shaped metamaterial metal hollow absorbing layer is insensitive to the polarization and polarization direction of the incident terahertz waves, the direction of incident light is not required specially, the frequency range of resonance absorption through the metamaterial structure can be adjusted by changing the size of the cross-shaped graph, and maximum absorption in a certain specific wave band can be achieved. According to the terahertz wave detector, high absorption in the specific wave band can be achieved, the absorption frequency band is easy to adjust, detection sensitivity is high, and the terahertz wave detector is compatible with an MEMS technology, can be produced in an array mode and has wide application prospects.

The invention discloses a method for preparing iron-coated graphene. The improved Hummer method is used to prepare graphene, and then graphene, reducing agent, iron salt, stabilizer, complexing agent, surface treatment agent and pH regulator are used as raw materials, and the The iron/graphene composite material is prepared by in-situ reduction method; the iron-coated graphene provided by the invention has high electromagnetic wave absorption effect, and is an iron/graphene composite material with stable performance, and is applied to a new type of intelligent anti-interference electric meter box; the iron /Graphene composites can combine the high Snooker frequency, high saturation magnetization of iron particles and the better impedance matching of graphene, electric dipole polarization relaxation, etc., which can bring a wider absorption frequency band and Stronger absorption strength, better absorption and shielding effects can be obtained according to the frequency band and strength information of the jammer.

The invention discloses a preparation method of a flaky carbonyl iron powder wave-absorbing material based on application of a Bluetooth communication frequency band. The preparation method comprises the following steps: preheating carbonyl iron powder in vacuum, charging the preheated carbonyl iron powder and a ternary surface modifier together into a ball milling tank, using absolute ethyl alcohol as a ball milling medium, conducting uniform stirring and ball milling treatment, and finally conducting charging into a vacuum drying chamber for conducting drying to obtain the wave-absorbing material. The flaky carbonyl iron powder wave-absorbing material prepared by the method has the advantages of thin wave-absorbing coating, light surface density, wide absorption band, strong absorbability, good mechanical properties, simple preparation and the like. The flaky carbonyl iron powder wave-absorbing material can meet the following requirements: the reflection loss (RL) of the wave-absorbing material is computed according to the transmission line theory, and when the coating thickness is 2mm, the peak value of reflection loss reaches -15dB around 2GHz, and the real absorption frequency width is 1GHz (1.6-2.6GHz) when RL is less than -10 dB, thereby completely covering the all band (2.4-2.485 GHz) of Bluetooth.

The invention relates to a manufacturing method for a broadband THz wave absorber unrelated to wide-angle polarization. The manufacturing method includes that semiconductor silicon with certain doping concentration is selected, a photolithography technique and an ICP (inductively coupled plasma) technique etching or a chemical corrosion technique are adopted on the surface of a silicon wafer to obtain periodically arranged grating layers with reduced reflectivity, and the rest part of the grating layers is a substrate layer with reduced transmissivity. By the arrangement, broadband absorber unrelated to the wide-angle polarization is realized in a THz band. Compared with a conventional metamaterial absorber, the high-doping silicon substrate absorber with the two-dimensional grating structure has the advantages of high absorption frequency band, unrelated to polarization, wide in incident angle and the like; the manufacturing method of the absorber is wide in material taking, simple and efficient, convenient to manufacture and wide in application range; the broadband THz absorber unrelated to the polarization can be manufactured according to actual application scenarios and demands, and absorption rate, absorption frequency band and absorption broadband can be regulated through regulation of structural parameters.

The invention provides a preparation method of a polypyrrole/BaFe12O19-Ni0.8Zn0.2Fe2O4/graphene nano wave-absorbing material. Firstly a BaFe12O19-Ni0.8Zn0.2Fe2O4 material is prepared by adopting a sol-gel method, and then the polypyrrole/BaFe12O19-Ni0.8Zn0.2Fe2O4/graphene composite material is prepared by adopting an in situ oxidation method and a mechanical reduction method. The prepared polypyrrole/BaFe12O19-Ni0.8Zn0.2Fe2O4/graphene composite material has the advantages that polypyrrole, graphene with large specific area, good electrical conductivity and stable performance and a hard and soft magnetic composite material BaFe12O19-Ni0.8n0.2Fe2O4 are compounded, so that wave-absorbing property of the polypyrrole/BaFe12O19-Ni0.8Zn0.2Fe2O4/graphene composite material is enhanced; polypyrrole has the advantages of low specific gravity, good compatibility and good electrical conductivity when being taken as a wave-absorbing material; the polypyrrole/BaFe12O19-Ni0.8Zn0.2Fe2O4/graphene composite material is prepared by adopting the mechanical reduction method, and significance is produced for broadening a microwave absorption frequency band of the composite material and preparing a novel wave-absorbing material.

The invention discloses a method for preparing a Fe/Co/C composite wave-absorbing material on the basis of pyrolysis of a modified MOF material. The method for preparing the Fe/Co/C composite wave-absorbing material on the basis of pyrolysis of the modified MOF material comprises the steps of using metal salts and organic ligands as raw materials, and adding a modifying agent to prepare an organicmetal frame structure precursor with a controllable structure; mixing and grinding the organic metal frame structure precursor with the controllable structure together with a solution containing specific metal ions; and finally, converting an MOF material mixed with specific metal ions into two-magnetic-metal and porous carbon composite material, namely, the Fe/Co/C composite wave-absorbing material, via high-temperature calcination under inert gas protection. The Fe/Co/C composite wave-absorbing material prepared with the method for preparing the Fe/Co/C composite wave-absorbing material onthe basis of pyrolysis of the modified MOF material, disclosed by the invention, possesses dielectric loss performance and magnetic loss performance; when the matching thickness is 3 mm, the Fe/Co/C composite wave-absorbing material reaches maximum absorbing strength of -49.94 dB at 10.64 GHz; the effective absorption frequency width of the Fe/Co/C composite wave-absorbing material is 8.56-13.6 GHz, and the Fe/Co/C composite wave-absorbing material has an important application value in the field of wave-absorbing materials.

The invention discloses an optical modulation terahertz broadband wave absorber based on doped silicon. A three-layer structure comprises a silicon substrate layer, a metamaterial layer and an opticalpumping source, which are sequentially arranged from bottom to top; the silicon substrate layer and the metamaterial layer are both boron-doped p-type silicon materials; and the metamaterial layer iscomposed of a unit structure array. The unit structure arrays are periodically arranged on the silicon substrate layer in an xoy plane; terahertz waves are incident on the wave absorber; the opticalpumping source is coupled into the wave absorber and excites electromagnetic resonance to realize broadband absorption of terahertz waves; and the optical pumping source generates a pumping light beamwhich is directly incident on the silicon substrate layer and the metamaterial layer to change the carrier concentration of doped silicon and realize the modulation function of the wave absorber on the absorption frequency band and the absorption rate of the terahertz waves. The terahertz wave absorption device is simple in structure, single in material, easy to process, high in terahertz wave absorption rate and wide in absorption bandwidth, has a light modulation function, and can be widely applied to multiple fields of imaging, stealth, communication, terahertz detection and the like.

The invention provides a frequency-adjustable microwave absorber, which is formed by a plurality of wave absorbing units on the sub wave length dimension through regular arrangement in the orthogonal direction. The frequency-adjustable microwave absorber is characterized in that capacitance and inductance coupling units are processed on the upper surface of a medium base plate, variable capacitance diodes are used for welding the adjacent capacitance and inductance coupling units, the positive and negative electrodes of each variable capacitance diode are respectively connected with a direct current feed line arranged at the back side of the medium base plate through one metallization through hole, all feed lines are combined into a feed network, the feed network at the lower surface of the medium base plate is divided into two parts including a positive part and a negative part, the two parts are respectively connected with the negative electrodes and the positive electrodes of all of the variable capacitance diodes, and the reverse bias is exerted on all of the variable capacitance diodes arranged on the upper surface of the medium base plate, and the current voltage source voltage is regulated in a range not exceeding the breakthrough voltage value of the variable capacitance diodes for changing the equivalent parameters of the variable capacitance diodes. The frequency-adjustable microwave absorber has the adjustable characteristics, the absorption frequency points in the wider bandwidth range are continuously adjustable, in addition, the regulation is very convenient, and wide application prospects can be realized in the fields of invisibility, radiation meters and the like.

The invention discloses a broadband absorber based on a double-ring structure of graphene. With metal as a reflective substrate, an insulating dielectric layer and a graphene layer are above the reflective substrate in order. The graphene layer is formed by a periodic monolayer graphene double-ring structure. Since the graphene exhibits strong metallicity in infrared and terahertz bands, a graphene structure is directly used as a resonant structural unit, a strong resonance coupling between graphene nanostructures realizes a single-layer broadband absorber, and the processing process of the structure is greatly simplified. Because of the unique electrical properties of the graphene, a chemical potential and a surface conductivity can be changed by the change of applied bias voltage, and the absorption frequency range of an absorbing structure is regulated. The broadband absorber has the advantages of a simple structure and high absorption efficiency and has important application prospects in the fields of terahertz imaging, sensing, a continuous light source and the like.

The invention relates to a pumping light frequency stabilization method for an SERF atomic spinning gyro. A pumping light frequency stabilization device is used for achieving pumping light frequency stabilization device, the pumping light frequency stabilization device comprises a pumping light frequency stabilization atomic air chamber, a heating device, a detector, a feedback signal processor and a laser controller, a beam of light is split from a light path, the split light passes through the air chamber only comprising alkali metal atoms, and high-stability frequency can be achieved by a narrow absorption peak; and meanwhile, by additionally arranging the feedback signal processor and the laser controller, frequency stabilization control is performed on output light frequency of pumping light, high-stability frequency is achieved, and a complicated light path brought by saturated absorption frequency stabilization is prevented.