116results about How to "Improve matching characteristics" patented technology

The invention discloses a direct-current power distribution network protection method based on voltage characteristic traveling wave similarity measurement. According to the method, the transient voltage currents at the two ends of a line after a direct-current fault occurs are subjected to high-frequency sampling, and are converted into line mode voltage forward traveling wave of one side of a protection area and line mode voltage inversion traveling wave of the opposite side; and based on traveling wave refraction reflection and polarity difference of intra-region and extra-region faults offorward inversion traveling wave at the two ends caused by mismatching of impedance of fault points, the similarity between the two waveforms is reflected by utilizing a globally optimal neighborhooddiffusion compatible dynamic matching similarity measure algorithm, so that the intra-region and extra-region faults can be reliably identified. According to the method, the traveling wave transmission delay and the time-to-time error can be compensated, influence from the sampling frequency deviation at the two ends, data missing and damage and the like is not caused easily, the fault tolerance is relatively high, the detection speed is high, and the power supply operation of the direct-current power distribution network is more reliable.

An operational amplifier with two differential pairs coupled to different current sources. The gate terminals of the transistors in the first differential pair are used as input terminals providing common mode input for most of the rail-to-rail voltage. The bulk terminals of the transistors in the second differential pair are used as input terminals providing common mode input for the remainder of the rail-to-rail voltage to thereby accomplish full rail-to-rail common mode. By using the bulk terminals of the field effect transistors in the second differential pair, rather than the gate terminals, as the input terminal, the operational amplifier may be constructing in a single well, thereby being compatible with standard digital CMOS processes. Alternatively, the bulk-driven transistors may be replaced with gate-driven depletion type transistors. The high voltage transistors in the output stage further reduce the offset voltage of the operational amplifier.

The invention relates to a digital preamplifier for an MEMS microphone, which comprises an Sigma Delta modulator and an MEMS polarization voltage generation module, wherein a first-stage integrator ofthe Sigma Delta modulator adopts a structure of a continuous time integrator, and various stages of integrators after the second stage adopt a structure of a switched-capacitor integrator; an input end of the continuous time integrator adopts a gate differential input circuit; and a wake source of the gate differential input circuit is connected with an integrating resistor and a feedback currentof the continuous time integrator respectively. The digital preamplifier meets the requirement of a new-generation advanced audio system on the input end, greatly promotes the anti-jamming ability ofthe conventional analog signal transmission path, improves the transmission quality of analog signals, and reduces physical space and design cost.

Disclosed are a method and a mounting device for installing a vehicle door hinge. More specifically, the mounting device f includes a jig frame, at least one clamping unit which is mounted to the jig frame and fixes the jig frame to a side panel and at least one mounting unit which is connected to the jig frame and is configured to install a door hinge which may be mounted to the side panel. In particular, the mounting unit is rotatable based on a slope dispersion of the side panel.

The invention discloses a cladded pumping optical fiber capable of efficiently adsorbing pumping light and belongs to the field of manufacturing of a special optical fiber. The optical fiber comprises a fiber core, an inner cladding layer and an outer cladding layer from inside to outside sequentially, wherein the refractive index of the inner cladding layer is gradually reduced from the direction of the fiber core to the direction of the outer cladding layer; the refractive index of the fiber core is more than the maximum refractive index of the inner cladding layer; the refractive index of the outer cladding layer is less than the minimum refractive index of the inner cladding layer; and the section of the inner cladding layer is in a round shape. By the cladded pumping optical fiber, the problems of difficulty of the double cladding layer optical fiber with a step refractive index profile circle symmetric inner cladding layer structure in pumping adsorption and high splicing loss, low flexibility and the like of the double cladding layer optical fiber with a non-circle symmetric inner cladding layer structure are solved. In the invention, a rare-earth doped optical fiber has the characteristics of high pumping adsorption, low splicing loss, high flexibility and the like, is easy to manufacture and is very suitable for manufacturing a high-power pumping coupling optical fiber laser and a high-power pumping coupling optical fiber amplifier with high cost performances.

The invention discloses a hybrid fiber reinforced resin matrix sandwich structural absorbing material and its preparation method. The absorbing material has a multifunctional laminated structure from the outside to the inside comprising a first dielectric layer, an absorbed layer, a second dielectric layer and a reflecting layer, wherein the first dielectric layer and the second dielectric layer are both composed of a glass fiber reinforced resin matrix composite material; the absorbed layer is composed of a continuous silicon carbide fiber reinforced resin matrix composite material; and the reflecting layer is composed of a carbon fiber reinforced resin matrix composite material. The preparation method of the absorbing material comprises the following steps of: firstly, each kind of fiber that satisfies each functional layer is selected; secondly, with the resin as the matrix, according to the laminated order and thickness of each functional layer, the absorbing material provided by the invention is prepared by the resin matrix composite material molding technology. The absorbing material provided by the invention has advantages of simple structure, good parameter tolerance, excellent wave absorbing function and low material cost, and furthermore is easy to mold.

The invention relates to the technical field of mixed air exhaust systems, in particular to an ultra-compact and high-mixing-efficiency air exhaust system structure adopting a de-swirl lobe mixer. The ultra-compact and high-mixing-efficiency air exhaust system structure adopting the de-swirl lobe mixer is especially suitable for a high-performance aviation gas turbine fan engine. The ultra-compact and high-mixing-efficiency air exhaust system structure adopting the de-swirl lobe mixer comprises the de-swirl lobe mixer with an inlet flow angle, a central cone with a bump and a mixing spray tube; a plurality of wing type reinforcing rib connecting structures are arranged between the de-swirl lobe mixer and the central cone; the lower ends of wing type reinforcing ribs are fixedly connected to the central cone with the bump; the upper ends of the wing type reinforcing ribs are fixedly connected to a de-swirl lobe trough; a trough lobe is a specially-shaped blade structure; the specially-shaped blade has an inlet flow angle; the side wall of the lobe mixer is subjected to concave sector cutting processing; and distances between the front edges of the lower ends of the reinforcing ribs to bump slope of the central cone are 0-3 times chord length of the reinforcing ribs. The ultra-compact and high-mixing-efficiency air exhaust system structure adopting the de-swirl lobe mixer has a plurality of advantages of being high in mixing efficiency, strong in pre-whirling resistance, compact in structure, high in reliability, low in processing and maintaining cost, and the like.

The present invention relates to a load sensor and provides a highly accurate load sensor with multi-layered wiring at low costs. It provides crystallized glass and non-crystalline glass which are best for a load sensor, and combines these to form multi-layered wiring, and further, makes a glass layer of composite type as needed, and reduces uneven printing in printing multiple layers with use of hardening type paste.

The invention discloses a high-sampling-rate broadband track and hold circuit and relates to the technical field of electrons. The track and hold circuit comprises an input buffer unit IB, a track/hold switch T/H, a holding capacitor CH and an output buffer unit OB. A full-differential circuit structure is introduced to realize good common-mode noise suppression ability; through the input and output buffers having emitter degeneration resistors, linearity of the track and hold circuit is improved; an improved switch emitter follower having a Schottky diode is adopted as a track and hold switch, so that circuit stability is improved; and the track and hold circuit is designed by utilizing a GaAs HBT device having high cut-off frequency and good base-emitter match, thereby solving the defects of low sampling rate and narrow bandwidth of an existing sampling and hold circuit.

The invention discloses a wave-absorbing material for a silicon carbide fibre reinforced resin base sandwich structure and a preparation method thereof. The wave-absorbing material has a multi-functional layer laminated structure. The structure comprises a first medium layer, an absorbing layer, a second medium layer and a reflection layer; all the functional layers consist of a continuous silicon carbide fibre reinforced resin base composite material; and the continuous silicon carbide fibres serving as the reinforcing materials in each functional layer have different specific resistances. The preparation method for the wave-absorbing material comprises the steps as follows: the continuous silicon carbide fibres are selected firstly and woven into plain cloth; and then the resin is used as a basal body and the wave-absorbing material is manufactured by adopting a resin base composite material forming technique according to the laminated sequence and thickness of each functional layer. The wave-absorbing material has the advantages of simple structure, good parameter tolerance level, easy forming, excellent wave-absorbing functions, etc.

A filter including a body on which a waveguide groove, whose one surface is open, is formed in a U-shape and a plurarity of inductive resonant windows are provided along a longitudinal direction of the waveguide groove at a predetermined interval in the waveguide groove; and a cover being provided on a top surface of the body so as to cover the surface being open, wherein the plurality of inductive resonant windows are provided in such a manner that a cavity, which is enclosed by two of the plurality of inductive resonant windows being adjacent, the body and cover, resonates at a predetermined frequency and passes a electromagnetic wave in a predetermined frequency band and wherein one end of the U-shaped waveguide groove is an input terminal and other end is an output terminal, and the input terminal and output terminal are formed on a same surface.

The invention discloses a potassium superoxide air regenerating device for emergent risk avoiding under coal mines, which comprises a device main body, wherein the device main body adopts a hollow cavity structure; the device main body comprises an air inlet area, a reaction area and an air discharge area from the bottom up sequentially; a lower air permeable diaphragm is arranged between the air inlet area and the reaction area; the reaction area is divided into an upper cavity, a middle cavity and a lower cavity; middle air permeable diaphragms are arranged between the three cavities; and each of the upper cavity, the middle cavity and the lower cavity is provided with a potassium superoxide reactor inside. The potassium superoxide air regenerating device is perfect and reasonable in structure, convenient in use and easy to maintain; the device requires no power when working; no substance harmful to human and the environment is generated during the working process and after the reaction is terminated; and while CO2 is eliminated, harmful gases such as CH4, CO, H2S, SO2, NOX and the like are absorbed and cleansed. The potassium superoxide air regenerating device provided by the invention is controllable and can be used for continuously supplying oxygen to airtight space.

A termination circuit for terminating a transmission line comprises a resistance unit which is formed by connecting a P-channel type MOS transistor and an N-channel type MOS transistor in parallel, and Thevenin termination is formed by providing this resistance unit between the transmission line and a power supply line and between the transmission line and a ground line.

This invention relates to a super-wide band plane single pole antenna including: a radiation element, an earth plate, a coaxial feed port, in which, the radiation element is vertical to the earth plate and connected with the coaxial feed port and composed of a trapezia and a circle with a top, which is inner-tangential with the trapezia to form a smooth transition unit.

The invention relates to an antenna, a low-frequency radiation unit and a radiation arm, the radiation arm comprises a radiation body, the radiation body is provided with a feed end, a tail end and aconductor section, the tail end and the feed end are oppositely arranged at an interval, the conductor section is arranged between the feed end and the tail end, and a scattering suppression structureis arranged in the contour area of the conductor section. The scattering suppression structure is provided with a current transmission path arranged corresponding to the conductor section, and the current transmission path is continuously arranged. The scattering suppression structure not only can suppress the intensity of the scattering signal and reduce the influence of the scattering signal onthe performance index of the high-frequency radiation unit, but also can reduce the influence on the impedance characteristic of the low-frequency radiation unit, so that the low-frequency radiationunit can keep a good matching characteristic.

The invention provides a PET/blast furnace slag composite cement-based wave-absorbing material and a preparation method thereof, belonging to the field of cross technology of electromagnetism and material science. The PET/blast furnace slag composite cement-based wave-absorbing material is prepared from the following raw materials: PET fragments, blast furnace slag, a wave-absorbing agent, polypropylene fiber, cement and water. The PET/blast furnace slag composite cement-based wave-absorbing material provided by the invention meets requirements on mechanical properties in engineering application, and has good electromagnetic wave absorption properties in a range of 2 to 18 GHz, a wide absorption frequency range, minimal reflectivity of -30 dB or below and a bandwidth of 12 GHz or above when reflectivity is -8 dB or below; and the prepared wave-absorbing material is low in density and thickness, high in strength, low in cost and simple in construction process.

The present invention discloses a watt level laser fiber beam combining device based on multimode fibers. The watt level laser fiber beam combining device comprises a laser generation module, a fiber beam combining module and a vibration motor. The output end of the laser generation module is connected with the input end of the fiber beam combining module, and the output end of the fiber beam combining module is wound on the vibration motor. The laser generation module emits multiple beams of watt level visible laser and enables the multiple beams of watt level visible laser to be coupled in the fibers, the multiple beams of watt level visible laser are combined into a beam of composite laser via the fiber beam combining module, and the vibration motor vibrates and drives the output end of the fiber beam combining module to vibrate to thereby eliminate the speckles in the composite laser. The watt level laser fiber beam combining device has lower parts precision requirements, can eliminate the speckles in the composite laser in a more economic manner, and can output the high-quality flat-topped light beams.

The invention discloses a high-power semispherical mutual coupling compensation medium antenna housing for a phased-array antenna, which comprises a semispherical or spherical crown-shaped high-dielectric constant medium housing cap (1), wherein the cap edge of the medium housing cap (1) is connected with the top part of an annular high-dielectric constant base (2); and the bottom part of the base (2) is fixed on an aperture plane (4) of the phased-array antenna. The medium antenna housing is used for the mutual coupling impedance compensation of the phased-array antenna, can match the impedance of the phased-array antenna and the impedance of free space, serve as an antenna housing to seal the phased-array antenna and withstand high internal air pressure, has high power capacity, is suitable for various polarized alloy antennae and has simple structure and easy processing.