832 results about "Invisibility" patented technology

The invention provides a novel magnetic mechanical anti-theft lock which comprises a wafer type key, a lock core rotor and a lock shell, and the wafer type key comprises a wafer; at least six magnetic blocks are arranged in the wafer, and the lock core rotor is a T-shaped cylinder on the appearance, and matches with the lock shell in a contacting way; a second magnetic spring blind hole and a magnetic spring are arranged in the position where the lock core rotor corresponds to the magnetic blocks, and the magnetic spring and the corresponding magnetic block are mutually repellent in terms of magnetism; an iron spring is respectively arranged in the position where the lock shell corresponds to the magnetic spring, and part of the iron spring convexly extends to the blind hole of the second magnetic spring; the bottom of the iron spring is also connected with a return spring, and the lock core fixing hole accommodates the narrow part of the lock core rotor. As the lock core of the lock has no key hole, destruction by tools such as a bolt driver, a screwdriver and the like can be prevented; besides, the key of the lock can not be easily duplicated, and the lock has multiple anti-theft functions, elegant appearance, strong invisibility and higher security.

A multi-version database system controls visibility of data during transaction processing. A transaction includes a transaction identifier that identifies the transaction and an invisibility list of transactions whose effects are invisible to the transaction. Changes made by other transactions are visible to the transaction based on the isolation level of the transaction. Records are visible to a transaction based on a creator identifier stored in the record that identifies the transaction that created the record.

A preparation method of a grapheme and ferriferrous oxide composite nanometer material belongs to the technical field of functional materials. The preparation method comprises the following steps: at first, oxidized grapheme is prepared by an improved chemical method; and then oxidized grapheme and ferric ions are adopted as raw materials, and are compounded through adopting a solvothermal technology to carry out one-step in-situ reduction to obtain the grapheme and ferriferrous oxide composite nanometer material. The preparation method solves the problems in the prior art that the interface binding force of grapheme and a magnetic material is insufficient, the appearances, the sizes and the magnetism of magnetic material particles are uncontrollable, and the magnetic material particles cannot be dispersed in water; the prepared composite nanometer material shows a microspheric appearance, has a loose surface and is high in specific surface area; through the change of the ratio of grapheme to the ferric ions, final magnetic property and electrical property of the composite material can be adjusted; and the controllable growth of the grapheme and ferriferrous oxide composite material is realized. The prepared grapheme and ferriferrous oxide nanometer microsheric material with magnetic and electric properties can be used in fields such as biological medicine, energy, invisibility and electronic materials.

The invention belongs to the technical field of materials and radomes and discloses an X/K-band composite metamaterial. The X/K-band composite metamaterial comprises a dielectric substrate made of nonconductive material. A metal foil layer is attached to the lower surface of the dielectric substrate, and a resistive film layer is attached to the upper surface of the dielectric substrate. The dielectric substrate, the metal foil layer and the resistive film layer are virtually divided into a plurality of periodically-arranged unit structures. A square metal foil is made on a metal foil layer of each unit structure by etching. A square circular resistive film is made on a resistive film layer of each unit structure by sputtering. Two slots identical in size and perpendicular to each other are made in each square metal foil by hollowing. The frequency selective surface structure of the X/K-band composite metamaterial allows a circularly-polarized microstrip patch antenna array to be consistent in good radiation characteristic under the K band; meanwhile, under the X band, the absorbing material structure of the X/K-band composite metamaterial can absorb incoming electromagnetic wave to allow invisibility.

The invention relates to an embedding, extracting and quantization step size coordination factor optimizing method of a digital watermark and a device thereof. The embodiment of an embedding method of the digital watermark comprises the steps that: an image to be embedded with the digital watermark is divided into image subblocks with preset size; DCT (discrete cosine transform) is executed to the image subblocks; SVD (singular value transform) is executed to the result after DCT so as to obtain a blocking singular value vector of the image subblocks; a texture masking parameter is calculated to obtain a brightness masking parameter; according to a quantization step size coordination factor, the brightness marking parameter and the texture masking parameter of the image subblocks, a self-adaptive quantization step size of the image subblocks is obtained; the self-adaptive quantization step size of the image subblocks and the blocking singular value vector are quantized to obtain a quantization value; amendment is carried out according to the quantization value and the information of the digital watermark to obtain an amendment value of the information of the digital watermark; and the amendment value containing the information of the digital watermark is utilized to obtain the image embedded with the digital watermark. The embodiment of the invention realizes the balance of the invisibility and the robustness of a digital watermarking method.

The invention discloses a composite frequency-selective-surface invisible radome and relates to the technical field of microwaves. The composite frequency-selective-surface invisible radome solves the problems that an existing radome is streamline in shape and cannot be spread to a plane, random preparation of an FFS (frequency selective surface) on the radome is difficult in process implementation, and FFS passband transmittance is low as incident angles of electromagnetic waves on the FFS are large. The composite frequency-selective-surface invisible radome is prepared by embedding an inner Y-ring-unit frequency-selective-surface conical cover into an outer radome by the aid of special laminating equipment. The composite frequency-selective-surface invisible radome has a band-pass filtering characteristic within a specific radar frequency range and good passband characteristics, is capable of efficiently transmitting through the working frequency range electromagnetic waves, reflects the out-of-band detection electromagnetic waves to a vast space according to the radome shape and reduces backward radar cross section so that invisibility of the radome is achieved. The composite frequency-selective-surface invisible radome can be used for invisibility of radomes of guided missiles and airplanes.

The invention relates to a video watermark treatment method, in particular to a DCT domain video watermark treatment method based on texture features, which belongs to technologies of information safety. The method comprises the steps of scrambling a watermark; calculating the brightness sum of a video image according to the color value of RGB of the video image, sequencing the brightness sum, selecting a frame for embedding, determining the middle position and the lower position of AC coefficients for embedding the watermark after the scrambling into the video image according to the texture distribution of the video image, carrying out distortion compensation on the video image with the embedded watermark by introducing motion compensation, reducing the video distortion caused during thewatermark embedding, and extracting and detecting the video image with the embedded watermark by utilizing the correlation of the watermark. The method has the advantages of good invisibility, stronganti-attack ability, good safety and real-time property and large capacity of embedded information.

The invention provides a novel two-dimensional vector nozzle which comprises a round-to-square barrel, synchronous actuators, link mechanisms, a contracting adjustment plate, vector actuators, link mechanisms, side walls, an extension adjustment plate, two-dimensional shield swirling center body structures, a bracket and a nozzle enclosure. The round-to-square barrel serves as a support member of the whole nozzle, the synchronous actuators, the link mechanisms, the contracting adjustment plate, the vector actuators, the link mechanisms and the extension adjustment plate serve as a main carrying capacity adjustment mechanism to achieve throat adjustment, outlet area adjustment and vector deflection, and the two-dimensional shield swirling center body structure is used for shielding a hot end member at the front end of the nozzle. The nozzle has the advantages that an adjusting range of a throat area of the conventional two-dimensional nozzle is not influenced, and the nozzle has good invisibility, a defect of the conventional two-dimensional vector nozzle in an invisibility function is overcome, and the nozzle has the advantages of simple structure and high reliability.

The present invention provides a multi-planar camera apparatus in which movable image capturing members that are connected to lateral space variators that are arranged to move laterally, horizontally and vertically in multiple planes and to cyclorotate, while capturing 3-D spatial images of the target-subject with enhanced depth angle and displaying directly through eye piece complexes or through a display unit. The multi-planar camera apparatus of the present invention is provided with a wider field of view to capture panoramic images of target-subjects. Further, the multi-planar camera of the present invention is equipped to capture 3-D spatial images of the target-subject without tilting or turning the body of the camera apparatus. Furthermore, the multi-planar camera apparatus of the present invention obliterates 3-D triangle of invisibility that forms between the image capturing members.

The invention discloses a super-matching wave-absorbing material formed by utilizing a sheeted cross-shaped metal unit structure. The super-matching wave-absorbing material consists of three layers of materials as follows: the bottom layer is a metal copper sheet, the middle layer is an FR4 printed circuit board and the top layer is composed of a plurality of slotted and sheeted cross-shaped metal copper sheets which are arranged on the middle layer (namely, the FR4 printed circuit board) at equal intervals; and the four opened ends of each cross-shaped metal copper sheet are respectively connected with slotted gaps by resistors. By adjusting the size of the welding resistance value, the sheeted cross-shaped metal unit structure resonates in a specified working frequency, the absorbed energy is consumed on the resistors, and simultaneously the complete matching with the air is realized. For the wave-absorbing material, the structure is simple, the thickness is small, the weight is light, the wave-absorbing efficiency is high, and the wave-absorbing material forms supermatching with the air, can be widely used for various military fields such as invisibility of aircrafts, naval vessels, radars, tanks and the like, as well as the civil fields such as electromagnetic shielding and electromagnetic protection.

The invention discloses a method for hiding the information of a JPEG (Joint Photographic Experts Group) digital image based on a modified quantization table, in particular to an improved quantization table 16*16 by changing the method of a traditional quantization table 8*8 in the JPEG standard and embedding 2 bits of information at the 2-LSBs (Least Significant Bit) of each low and medium frequency coefficients in the DCT domain after carrying out DCT (Discrete Cosine Transform) and quantization to the carrier image. On the basis of favorable robustness and invisibility, the method modifies the quantization table so as to fully extract secrete information to be hidden, greatly improve the capacity of the steganographic method in comparison with a traditional Jsteg method and obatin higher hidden image quality.

The invention relates to an anti-counterfeiting authentication method of an anti-counterfeiting image of printed matter based on a digital watermarking technology. Most of encryption technologies and digital watermarking technologies only provide an anti-counterfeiting function for the digital field of an image and can not resist geometric attacks and attacks similar to printing, scanning, and the like. The method comprises the following steps of: firstly, processing a two-value bar code, and embedding the two-value bar code into a carrier image; then, printing once to form authorized printed matter; taking a picture of the printed matter by using a mobile phone, uploading the picture to an authentication center, and reading the watermark by using a detection algorithm to identify the authenticity of the printed matter so as to achieve the anti-counterfeiting purpose. Because the watermark embedded in the printed matter is invisible, the watermark has good invisibility and safety. The invention realizes the detection by using the mobile phone and has the advantages of equipment convenience, mobility, broad application prospect, and the like.

The invention discloses a binary vector spraying pipe capable of realizing an S-bent shading function, and belongs to the technical field of aero-engine spraying pipes. The binary vector spraying pipe is characterized in that the front section of a circular turning square barrel body (1) is connected with an engine to form a supporting structural member of the whole spraying pipe; an actuating barrel (2), a pull rod (3), a convergence adjustment plate (4), an expansion adjustment plate front section (5), an expansion adjustment plate rear section (6), an actuating barrel (8), a pull rod (9), an actuating barrel (10), a pull rod (11) and an expansion adjustment plate (12) are used as main bearing adjustment mechanisms, so that adjustment on a throat area and an outlet area, the S-bent shading function and a vector deflection function are realized. The binary vector spraying pipe retains a vector deflection function for conventional binary vector spraying pipe throat area adjustment and different-angle adjustment; the function for detecting whether a high-temperature component is completely shaded or not from the back of the engine can be realized, and high infrared hiding performance is achieved; the defect that the conventional S-bent spraying pipe cannot be adjusted is overcome, and vector deflection is realized; the binary vector spraying pipe is simple in structure, high in reliability and high in invisibility.

The invention pertains to the technical field of vehicle construction, discloses a blind zone detecting and alarm device for vehicles, wherein, an infrared probe (1) is multiple passive infrared receivers; the alarm device is divided into an audible alarm device and a light stroboflash alarm device. The infrared probe (1), the audible alarm device and the light stroboflash alarm device are all connected with the operating control unit of the vehicle by signal lines. Detection zones cover an A pole blind zone and blind zones at the side and the back of the vehicle by adopting the technical proposal, and the disadvantages of poor active infrared anti-jamming performance and complex structure are overcome; the passive infrared detector does not emit any radiation and has the advantages of quite low device power consumption, high sensitivity, comparatively good invisibility, low cost, convenient arrangement and being artistic and practical; the mode combined with the audible alarm and the light stroboflash alarm gives drivers sufficient alarm information to guarantee driving safety.

The invention discloses a metamaterial antenna housing, including a polarization rotation metamaterial layer, a honeycomb structure layer and a frequency selection surface layer. The polarization rotation metamaterial layer includes a first dielectric substrate and a first metal structure layer; the frequency selection surface layer includes two second dielectric substrates, a second metal structure layer, a third metal structure layer and a fourth metal structure layer; and the first dielectric substrate and the second metal structure layer are attached to surfaces of two sides of the honeycomb structure layer respectively. Therefore, through arrangement of the polarization rotation metamaterial layer, the honeycomb structure layer and the frequency selection surface layer, the metamaterial antenna housing provided by the embodiment of the invention can realize efficient wave transmission of electromagnetic waves in a radome working band on the frequency selection surface, the metamaterial layer can be utilized to rotate the polarization direction of reflected electromagnetic waves out of the working band, mismatch of polarization modes of the reflected electromagnetic waves and energy detection electromagnetic waves is caused, thereby achieving the purpose of invisibility to an energy detection radar system, and thus the metamaterial antenna housing has important application prospects.

The invention discloses a broadband bionic yagi antenna with a low radar cross section and mainly solves the problems of high radar cross section and relatively narrow band width in the traditional yagi antenna. The antenna simulates an opposite phyllotaxis plant leaf structure and comprises a director (2), a radiating element (3), a parallel strip line (4), a reflector (5) and a coaxial conversion joint (6). The radiating element (3) is of an oval structure, the director (2) simulates a feather-shaped leaf structure, and the reflector (4) is a rectangle patch with a tooth-shaped structure. The radiating element (3) is printed on a top layer and a bottom layer of a double-layer medium material plate (1) and respectively connected with an inner core and an outer core of the coaxial conversion joint (6) by the parallel strip line (4); the director (2) is printed on the top layer of the double-layer medium material plate (1); and the reflector (4) is printed between two layers of the double-layer medium material plate (1). The broadband bionic yagi antenna with the low radar cross section has the advantages of wide frequency band and good invisibility performance and can be used on an invisible target carrier.

The invention discloses a method and device for embedding and extracting digital watermarking. The method comprises the steps of: conducting discrete cosine transform (DCT) to a low-frequency area obtained by generating a CDMA (Code Division Multiple Access) watermarking sequence and carrying out discrete wavelet transform (DWT) to a host image; embedding the CDMA watermarking sequence into a medium-high frequency DCT coefficient sequence determined by a secret key. No color loss can be ensured in color mode translation by embedding watermarking in the LAB color space of the image, the robustness and invisibility of the watermarking can be improved by adding watermarking onto the DWT and DCT transformed coefficient of the image, and the capacity of the watermarking can be increased through the CDMA coding technique.

The invention belongs to the field of anti-counterfeiting technology for products, and provides a hidden information grating unlocking anti-counterfeiting method and a system. The hidden information grating unlocking anti-counterfeiting method can be directly implemented by means of normal printing (lithographic offset printing, flexographic printing, intaglio printing, metal lithographic offset printing, silk screen printing and digital printing), can be used for printing on surfaces of any printed materials (such as paper, paperboards, plastic films, tinplates and the like), no production costs are added, hidden images and texts only can be detected by a special grating unlocking film, a graph of anti-counterfeiting content of a product is hidden by grating anti-counterfeiting technology, hidden patterns are displayed via the grating unlocking film, high invisibility and security are realized, the hidden images and texts cannot be reprinted by means of enlarging, scanning or copying, otherwise hidden information can be lost, scanning and preprinting preventive functions are powerful, counterfeit and shoddy products can be stopped against entering markets from the sources, the hidden information grating unlocking anti-counterfeiting method brings great convenience for enterprises to crack down on fake products and maintain benefits of consumers, and the technological content of products of packaging and printing enterprises can be increased.

Systems and methods are presented for achieving various operational modes of packetized wireless network communication, specifically IEEE 802.11 Wireless LAN (WLAN), 802.16 Wireless MAN and WiMAX communication. By providing for various operational modes an increase in the overall security of the wireless network can be realized. The invention is based on the application of a single cryptosystem and on the application of multiple cryptosystems. The invention addresses to aspects of WLAN security, namely, the protection of the information transmitted through the radio link of WLANs, and the invisibility of the network equipment, such as Access Points (APs), to unauthorized adapters.

The invention discloses a frequency-selection-surface invisible radome with a dielectric medium truss structure and belongs to the technical field of modern weapons. The radome takes a dielectric medium truss as a skeleton network to support an FSS (frequency Selective Surface) flexible screen so as to realize a stable filtering characteristic and further improve the invisibility and reliability of the FSS radome. The radome comprises a radome base, the dielectric medium truss, a flexible base and the FSS screen; the radome is of a closed structure and sequentially comprises the radome base, the dielectric medium truss, the flexible base and the FSS screen from the outermost layer to the innermost layer; and the radome base, the dielectric medium truss, the flexible base and the FSS screen are connected with adjacent parts. According to the invention, the ideal filtering characteristic of the FSS radome which utilizes air as a matching medium can be realized, the stable passband of electromagnetic waves which are incident with large angels and in different polarization ways can be maintained, and detection radar waves emitted by an enemy can be reflected to other directions so as to reduce echo signals, thereby realizing the aim of invisibility of a radar.

The invention discloses a wavelet domain color image watermark encryption algorithm based on differential evolution. The operating method comprises the following steps: performing color space transformation on an original image to obtain a YIQ color format suitable for a human vision system and extracting a brightness component Y; adopting Arnold scrambling on a watermark image; performing three-stage discrete wavelet decomposition on the component Y of the original image to generate four sub-bands of different frequencies by utilizing discrete wavelet transform, thereby obtaining a sub-band image; representing a sub-band image matrix by using A, and performing singular value decomposition on the image subjected to three-stage wavelet decomposition; performing primary discrete wavelet decomposition on the watermark image subjected to scrambling encryption processing; performing watermark embedding; adaptively optimizing and selecting embedding strength by adopting differential evolution, and adding watermark information into the original image subjected to singular value decomposition in a multiplicative addition form. The invention has the beneficial effects that the watermark algorithm has high invisibility and is high in robustness.

The invention discloses a video watermarking method based on a visual attention mechanism. Binary-system watermark information is embedded into a DCT domain in a visual non-saliency area of an MPEG-2 video key frame is selected to achieve the purpose of video copyright protection. The video watermarking method comprises the following steps of decoding a carrier video and obtaining the video key frame I; adopting a Koch and Itti visual remarkable model to analyze visual saliency of the video key frame and dividing a visual saliency area; selecting the visual non-saliency area human eyes are not too sensitive to, performing fixed-step-length odd-even quantization index modulation on a DCT direct current coefficient of luminance component and embedding watermark information; analyzing the visual saliency of the video key frame with embedded watermarks, judging a watermark embedding area and extracting the watermark information according to watermark embedding rules. The visual attention feature of the human eyes is effectively utilized in the video watermarking method, the invisibility of the video watermarks is improved, the video watermarking method has good robustness on common video attacks, and contradiction between the watermark invisibility and the robustness is effectively relieved.