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31results about How to "Meet frequency requirements" patented technology

Voltage conversion circuit, method and polyphase parallel power supply system

Embodiments of the invention provide a voltage conversion circuit, a method and a polyphase parallel power supply system. In the voltage conversion circuit, through a feedback circuit, a feedback ripple signal with a controllable frequency is provided so that a work frequency of the voltage conversion circuit in the embodiments is controllable and a demand of a load to the frequency can be satisfied. And a response speed is fast in a hysteresis model without compensation. Simultaneously, because the work frequency is fixed, the voltage conversion circuit in the embodiments can be applied to the polyphase parallel power supply system so as to satisfy an application scene of a large load current.
Owner:HUAWEI TECH CO LTD

Urban railway double-crossover middle turning device and method for eliminating lateral bending and upwarping of beam body

The invention relates to an urban railway double-crossover middle turning device and a method for eliminating lateral bending and upwarping of a beam body. A butt joint part between a first rotary beam and a second rotary beam is of a lug boss lap-joint structure and is located on a base through a rotary table, the lower part of a non-butt-joint part of each of the first rotary beam and the second rotary beam is provided with a trolley moving mechanism, the trolley moving mechanisms are located on bases, a drive guide slot is arranged at the bottom of each of the first rotary beam and the second rotary beam, one ends of two drive arms are respectively located in the drive guide slots, the other ends of the two drive arms are respectively connected with a power output end of a respective reduction gear, the power input ends of the reduction gears are respectively connected with a power output end of a double-end motor reduction gear through a transmission shaft and a transmission shaft support frame, two locking frames are respectively located on the bases for supporting the non-butt-joint parts of the first rotary beam and the second rotary beam, and two locking mechanisms are respectively located at the back parts of the non-butt-joint parts of the first rotary beam and the second rotary beam and are respectively matched with the locking frames in a locking or opening manner.
Owner:CHINA RAILWAY BAOJI BRIDGE GRP

Frequency-adjustable ultralow-frequency mechanical antenna structure

The invention discloses a frequency-adjustable ultra-low frequency mechanical antenna structure and belongs to the technical field of ultra-low frequency communication. The antenna structure comprisesa static magnetic field generation module for generating a static magnetic field and a static magnetic field cutting module for cutting the static magnetic field generation module to generate an electromagnetic field changing with time, and the static magnetic field generation module comprises a motor, a plurality of permanent magnets and a supporting frame for fixing the rotating motor and the plurality of permanent magnets; the supporting frame is arranged outside the motor; the plurality of permanent magnets are uniformly arranged on the outer surface of the supporting frame; the static magnetic field cutting module comprises a disc, a wafer with sawteeth and a control switch for controlling the sawtooth length change of the wafer and driving the wafer to move; the number of teeth of the sawtooth wafer is the ratio of the time-varying magnetic field frequency to the working frequency of the rotating motor, and by changing the mechanical motion mode, the frequency of electromagneticwaves generated by a mechanical antenna is improved while the weakening of the magnetic induction intensity is reduced as much as possible, so that the requirement for the frequency in the transmission process is met.
Owner:DALIAN JIAOTONG UNIVERSITY

Fast-recovery commutation diode used for high frequency electroplating and production method thereof

The invention relates to a fast-recovery commutation diode used for high frequency electroplating and a production method thereof, wherein the fast-recovery commutation diode has the high frequency property and is suitable for 30KHz / 2-5KA / (200-400)V high frequency electroplating with both high voltage and high current density. An N-type (100) radial single crystal silicon piece, which has specific resistance Rho n of 5-9 Ohm-cm, diameter of 48-70 mm and thickness of 175-185 microns, is adopted; silicon piece diffusion is conducted, and double-surface once diffusion is carried out at temperature of 1250 DEG C; the diffusion piece detection is carried out; phosphorosilicate glass and borosilicate glass are used for absorption, the temperature is slowly lowered from 1250 DEG C to 1050 DEG C, the speed rate is 1 DEG C per minute, and isothermal absorption is carried out for 2-3 h; slow temperature reduction is continued till furnace temperature is reduced to 600 DEG C, then furnace delivery is carried out, and minority carrier lifetime Tao p is caused to reach 12-16 Mu S; platinum diffusion is carried out at low temperature so that the minority carrier lifetime Tao p is controlled to be 4-6 Mu S; 12 Mev electron irradiation is carried out so that the minority carrier lifetime Tao p of a base region is 0.9-1.1 Mu S; the two surfaces of the silicon piece are plated with titanium-nickel-gold by means of vapor deposition and then undergo table-board spray sand molding, desanding, cleaning, corrosion, passivation protection, intermediate test, shell arrangement and packaging, and after tests testify qualification, the finished product is produced.
Owner:JINZHOU SHENGHE POWER ELECTRONICS

Dynamic primary thermal power generating unit frequency modulation control method for power grid with high wind power penetration rate

The invention discloses a dynamic primary thermal power generating unit frequency modulation control method for a power grid with the high wind power penetration rate, and relates to a dynamic primary thermal power generating unit frequency modulation control method. In order to reduce influences caused by wind power output power fluctuation on system frequency stabilization, the primary frequency modulation control method for dynamically adjusting a difference adjustment coefficient of a thermal power generating unit is proposed by analyzing the frequency response characteristics of the thermal power generating unit when primary frequency modulation is conducted on the thermal power generating unit on the premise that the stability of the thermal power generating unit is guaranteed. According to the control method, the primary frequency modulation capability of the thermal power generating unit can be effectively improved, the thermal power generating unit can achieve the higher flexibility and capability when primary frequency modulation is conducted on the thermal power generating unit, and therefore frequency stabilization of a wind power-containing system is promoted. In a wind power-containing single-area simulation system, when 15% of wind power prediction errors are taken into account, the maximum fluctuation deviation of the system frequency is decreased to 0.0663 Hz from 0.126 Hz, and therefore the requirement of the power grid on the frequency is met. The control method is applied in the field of thermal power generating unit control.
Owner:HARBIN INST OF TECH

Epoxy resin composition and application thereof

The invention provides an epoxy resin composition which comprises an epoxy resin mixture, a phenolic resin, a curing accelerator, an inorganic filling material, a release agent and a coupling agent, wherein the epoxy resin mixture at least comprises an epoxy resin shown in a formula I; and in the formula I, R1 and R2 independently are hydrogen or C1-C4 alkyl, and n is an integral within a range of 0-50. According to the invention, the defects that the traditional epoxy resin composition is not environment-friendly, and the requirements of semi-conductor packaging has less possibility of being met caused by adding a large amount of environmental-friendly fire retardants in the existing epoxy resin composition are overcome, thus the epoxy resin composition which has the advantages of environmental friendliness, good high-temperature reliability, high piezoelectric property and good molding formability is provided. The invention also provides application of the epoxy resin composition in green packaging of various surface mounted devices (SMDs), especially in environmental-friendly packaging of a high piezoelectric SMD. The formula I is shown in the specification.
Owner:HENKEL HUAWEI ELECTRONICS

Automatic hydraulic generating speed bump device

The invention discloses an automatic hydraulic generating speed bump device. A modularized installing mode is adopted. The automatic hydraulic generating speed bump device specifically comprises a pulse-type power source module, a continuous energy supply module and a generating module. Hydraulic circuit connection is adopted between the modules. The pulse-type power source module comprises a camlink mechanism, a plunger-type cylinder, a throttle valve, a piston cylinder, a one-way valve, a spring, a filter, a pilot-type overflow valve, a damper and a two-bit two-way magnetic exchange valve.The continuous energy supply module comprises a two-bit three-way magnetic exchange valve and an energy accumulator. According to the automatic hydraulic generating speed bump device, a pulse-type power source is adopted, so energy charged into the energy accumulator by a system within unit time is improved; a mode of alternate charging of the double energy accumulators is adopted, so a problem that the energy cannot be recovered while the single energy accumulator discharges the energy is solved; and vibration energy generated while a vehicle passes through a speed bump is converted to electric energy and secondary utilization is performed. The automatic hydraulic generating speed bump device is good in applicability, high in energy recycling efficiency, and strong in reliability.
Owner:YANSHAN UNIV

Dynamic frequency allocation method for cognitive radio cellular network

InactiveCN102026204AAvoid distractionsSolve the problem of dynamic frequency allocationNetwork planningFrequency spectrumControl channel
The invention relates to a dynamic frequency allocation method for a cognitive radio cellular network, belonging to the technical field of cognitive radio. The dynamic frequency allocation method comprises the following steps: creating a real-time interference frequency list according to available frequency spectrum information of each cell sensed by a base station and a cognitive mobile subscriber; then creating a cost function according to the number of frequencies required by each cell and inter-cell interference constraint conditions; and minimizing the cost function by a noise chaotic neural network method, thus meeting the frequency requirement of each cell, avoiding interference to an authorized user, also avoiding inter-cell interference and maximizing the frequency spectrum utilization. Meanwhile, in the invention, the frequency with minimum number of each cell is locked, so that each cell can be relatively stably allocated with one frequency as a common control channel.
Owner:YANGTZE UNIVERSITY

Binary frequency reconfigurable microstrip antenna

The invention discloses a binary frequency reconfigurable microstrip antenna, and belongs to the technical field of basic electrical elements. The frequency reconfigurable antenna is composed of an intermediate layer dielectric substrate, an upper layer microstrip structure arranged on the intermediate layer dielectric substrate and a bottom layer metal floor with a rectangular defected ground structure, the upper-layer microstrip structure comprises a short microstrip feeder line, a long main microstrip line and microstrip annular structures with different sizes, wherein the microstrip annular structures surround the two sides of the main microstrip line. A gap is reserved between the main microstrip line and each of the annular structures on the two sides to place three PIN diodes, and the effective electrical length of the antenna is changed through on-off of the diodes to achieve the three-bit binary frequency reconfigurable characteristic. The design is simple in structure and small in size, is realized in the form of a microstrip circuit, only uses three PIN diode switches to realize eight different working states, can meet the frequency requirements under different communication systems, has a directional diagram in a low-frequency working state similar to the directional diagram of a half-wave oscillator, and realizes omnidirectional radiation on an H surface.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Phase-locked loop and calibration method of voltage-controlled oscillator of phase-locked loop

The technical scheme of the invention provides a phase-locked loop and a calibration method of a voltage-controlled oscillator of the phase-locked loop. The phase-locked loop comprises: a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, a frequency divider and a calibration circuit; the calibration circuit is used for acquiring the frequency of an output signal of the voltage-controlled oscillator, calibrating the frequency of the output signal of the voltage-controlled oscillator according to the expected frequency, acquiring a frequency control parameter of the voltage-controlled oscillator under the current signal frequency, acquiring an amplitude control parameter and a gain control parameter according to the frequency control parameter, and keeping the amplitude and the gain of an output signal of the voltage-controlled oscillator constant according to the amplitude control parameter and the gain control parameter. The phase-locked loop provided by the invention can meet the frequency requirement of multiple protocols on the phase-locked loop, and can adaptively search and stably work at an appropriate frequency, so that the circuit hasthe optimal performance, and meanwhile, the problem that the amplitude of a signal output by a voltage-controlled oscillator is inconstant when the phase-locked loop works in a large frequency range is solved.
Owner:GOWIN SEMICON CORP LTD

Fast and accurate frequency detection method based on SOGI

InactiveCN111983307AWide range of frequency adaptationHigh precisionFrequency to phase shift conversionHarmonicSoftware engineering
The invention discloses a fast and accurate frequency detection method based on SOGI, and the method comprises the steps: carrying out the sampling and normalization of a single-phase voltage signal,and carrying out the IIR low-pass filtering of obtained normalized floating point data, so as to eliminate the impact caused by harmonic waves and inter-harmonic waves; and separating in-phase and quadrature components of a filtered signal by using an SOGI module, obtaining active and reactive components according to dq conversion, wherein the reactive component is known to be 0 according to physical significance, correction is carried out according to the physical significance, accurate phase and frequency information is obtained, the obtained frequency is a fluctuation quantity, a stable frequency detection result can be obtained by using a mean filtering algorithm, the filter adopts a lower order, and the coefficient of the filter is obtained by a computer and stored in Flash for calling; and three-stage series connection can be adopted for mean filtering, so that the frequency detection range is expanded.
Owner:青岛鼎信通讯科技有限公司 +1

Intermediate slewing device of urban rail transit crossing line and method for eliminating side bending and upward arching of beam body

The invention relates to an urban railway double-crossover middle turning device and a method for eliminating lateral bending and upwarping of a beam body. A butt joint part between a first rotary beam and a second rotary beam is of a lug boss lap-joint structure and is located on a base through a rotary table, the lower part of a non-butt-joint part of each of the first rotary beam and the second rotary beam is provided with a trolley moving mechanism, the trolley moving mechanisms are located on bases, a drive guide slot is arranged at the bottom of each of the first rotary beam and the second rotary beam, one ends of two drive arms are respectively located in the drive guide slots, the other ends of the two drive arms are respectively connected with a power output end of a respective reduction gear, the power input ends of the reduction gears are respectively connected with a power output end of a double-end motor reduction gear through a transmission shaft and a transmission shaft support frame, two locking frames are respectively located on the bases for supporting the non-butt-joint parts of the first rotary beam and the second rotary beam, and two locking mechanisms are respectively located at the back parts of the non-butt-joint parts of the first rotary beam and the second rotary beam and are respectively matched with the locking frames in a locking or opening manner.
Owner:CHINA RAILWAY BAOJI BRIDGE GRP

Wafer test device and method

The invention relates to a wafer test device and method. The test device comprises an interface card, wherein the interface card comprises a signal synthesis device, multiple first interfaces and a second interface, the signal synthesis device is used for synthesizing first signals emitted by multiple detectors into a second signal and transmitting the second signal to a wafer socket, the multiplefirst interfaces are arranged at an input end of the signal synthesis device and is used for connecting the multiple detectors, and the second interface is arranged at an output end of the signal synthesis device and is used for connecting the wafer socket. The test device is advantaged in that the first signals having low frequency emitted by the multiple detectors are synthesized by the signalsynthesis device into the second signal, and high-frequency test of a wafer is achieved through utilizing the multiple low frequency detectors.
Owner:CHANGXIN MEMORY TECH INC

Control method of air conditioning unit and related equipment

The invention relates to a control method of an air conditioning unit and related equipment. The control method comprises the following steps that a control instruction of an air conditioning unit exiting an oil return control mode or the control instruction of defrosting control mode is detected; if the control instruction is detected, operation states of compressors before the air conditioning unit enters the oil return control mode or the defrosting control mode is obtained, and the operation states of the compressors are single-compressor operation or at least two compressors are operated;and if the operation state of the compressor is the single-compressor operation, each compressor of the air conditioning unit is controlled to operate according to a first target frequency, the firsttarget frequency is larger than or equal to the lowest frequency when all the compressors normally run. Therefore, the frequency requirements of all compressors can be met, the problem that the compressors are out of step due to the fact that the operation frequency is low is avoided, so that the control effect of the air conditioning unit can be improved.
Owner:GREE ELECTRIC APPLIANCES INC

Structure for improving performance of TEM all-dielectric filter

The invention discloses a structure for improving the performance of a TEM all-dielectric filter, comprising a dielectric cavity block, a signal shielding metal sheet and a PCB substrate. The dielectric cavity block and the PCB substrate are welded together. One end of the signal shielding metal sheet is welded to the dielectric cavity block, and the other end is welded to the PCB substrate. The dielectric cavity block is provided with resonant holes. The inner wall of each resonant hole is plated with a silver layer, and the depth of the silver layers is less than 2 / 3 of the depth of the resonant holes. The structure is simple and convenient to manufacture. A silver layer of a certain depth is plated in the resonant holes of the existing TEM all-dielectric filter, and the height of silveris controlled according to the cavity material and size of the holes and the aperture of the resonant holes, so that the Q value of the TEM all-dielectric filter is improved while the frequency requirement of the TEM all-dielectric filter is satisfied. By controlling the ratio of the height of silver to the height of the resonant holes, the Q value of the TEM all-dielectric filter of the invention is at least 20% higher than that of the traditional TEM filter.
Owner:HONGKONG FINGU DEV CO LTD

An automatic hydraulic power generation deceleration belt device

The invention discloses an automatic hydraulic generating speed bump device. A modularized installing mode is adopted. The automatic hydraulic generating speed bump device specifically comprises a pulse-type power source module, a continuous energy supply module and a generating module. Hydraulic circuit connection is adopted between the modules. The pulse-type power source module comprises a camlink mechanism, a plunger-type cylinder, a throttle valve, a piston cylinder, a one-way valve, a spring, a filter, a pilot-type overflow valve, a damper and a two-bit two-way magnetic exchange valve.The continuous energy supply module comprises a two-bit three-way magnetic exchange valve and an energy accumulator. According to the automatic hydraulic generating speed bump device, a pulse-type power source is adopted, so energy charged into the energy accumulator by a system within unit time is improved; a mode of alternate charging of the double energy accumulators is adopted, so a problem that the energy cannot be recovered while the single energy accumulator discharges the energy is solved; and vibration energy generated while a vehicle passes through a speed bump is converted to electric energy and secondary utilization is performed. The automatic hydraulic generating speed bump device is good in applicability, high in energy recycling efficiency, and strong in reliability.
Owner:YANSHAN UNIV

A Binary Frequency Reconfigurable Microstrip Antenna

The invention discloses a binary frequency reconfigurable microstrip antenna, which belongs to the technical field of basic electrical components. The frequency reconfigurable antenna consists of an intermediate dielectric substrate, an upper microstrip structure disposed on the intermediate dielectric substrate, and a bottom metal floor with a rectangular defect ground structure, wherein the upper microstrip structure includes a short microstrip feed Electric wires, a longer main microstrip line and microstrip ring structures of different sizes around the two sides of the main microstrip line. A gap is left between the main microstrip line and the ring structures on both sides to place three PIN diodes, and the effective electrical length of the antenna is changed by switching the diodes to realize the three-bit binary frequency reconfigurable characteristic. The structure of this design is simple, the volume is small, and it is realized in the form of a microstrip circuit. Only three PIN diode switches are used to realize eight different working states, which can meet the frequency requirements of different communication systems. Similar to the direction diagram of the half-wave oscillator, omnidirectional radiation on the H-plane is realized.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

An acoustic metasurface experimental device

The invention discloses an acoustic meta-surface experimental device comprising a sound source excitation module, a meta-surface module and a detection and noise reduction module that are connected successively. The detection and noise reduction module is connected with a microphone. A sound wave is generated by the sound source excitation module and then is focused by the meta-surface module; andthen the microphone processes the sound pressure signal. The experimental device has advantages of simple structure and great convenience in mounting and dismounting. The output frequency band of theloudspeaker is wide; frequency requirements of different sound waves are met; and the sound source signal types are variable.
Owner:SOUTHWEST JIAOTONG UNIV

Cascaded Circuits and Cascaded Devices Based on Gate Protection

ActiveCN112382631BMeet switching speed needsReduced equivalent Miller capacitanceTransistorSolid-state devicesCapacitanceDriving current
The invention discloses a cascaded circuit and cascaded device based on gate protection. The cascaded circuit includes a high-voltage depletion device, a low-voltage enhanced device, and a low-voltage depletion device. The high-voltage depletion device includes The first gate, the first source and the first drain, the low-voltage enhancement device includes the second gate, the second source and the second drain, the low-voltage depletion device includes the third gate, the third source and a third drain, the first source is electrically connected to the second drain, the first gate is electrically connected to the second source, the second gate is electrically connected to the third source and the third gate connected, the first drain serves as the drain of the cascode circuit, the second source serves as the source of the cascade circuit, and the third drain serves as the gate of the cascade circuit. The invention can greatly reduce the equivalent Miller capacitance of the traditional enhanced device, and even when the gate drive current is severely limited by the gate protection unit, the device can still meet the requirements for the switching speed of the device in practical applications.
Owner:苏州英嘉通半导体有限公司

Epoxy resin composition and application thereof

The present invention relates to an epoxy resin composition, which comprises a mixture of specific epoxy resins, a phenolic resin, a curing promoter, an inorganic filler, and as optional components a release agent and a coupling agent. The epoxy resin composition of the present invention can be used in various electronic applications, such as in environmentally friendly, high voltage SMD packages.
Owner:HENKEL HUAWEI ELECTRONICS

Cascade circuit based on gate protection and cascade device

ActiveCN112382631AMeet switching speed needsReduced equivalent Miller capacitanceTransistorSolid-state devicesCapacitanceDriving current
The invention discloses a cascade circuit based on gate protection and a cascade device, the cascade circuit comprises a high-voltage depletion type device, a low-voltage enhanced type device and a low-voltage depletion type device, the high-voltage depletion type device comprises a first gate, a first source and a first drain, the low-voltage enhanced device comprises a second grid electrode, a second source electrode and a second drain electrode, the low-voltage depletion type device comprises a third grid electrode, a third source electrode and a third drain electrode, the first source electrode is electrically connected with the second drain electrode, the first grid electrode is electrically connected with the second source electrode, and the second grid electrode is electrically connected with the third source electrode and the third grid electrode. The first drain electrode serves as a drain electrode of the cascade circuit, the second source electrode serves as a source electrode of the cascade circuit, and the third drain electrode serves as a grid electrode of the cascade circuit. According to the invention, the equivalent Miller capacitance of a traditional enhanced device can be greatly reduced, and the cascade circuit can still meet the requirement on the switching speed of the device in practical application even if the grid driving current is seriously limited bythe grid protection unit.
Owner:苏州英嘉通半导体有限公司

Fast-recovery commutation diode used for high frequency electroplating and production method thereof

The invention relates to a fast-recovery commutation diode used for high frequency electroplating and a production method thereof, wherein the fast-recovery commutation diode has the high frequency property and is suitable for 30KHz / 2-5KA / (200-400)V high frequency electroplating with both high voltage and high current density. An N-type (100) radial single crystal silicon piece, which has specificresistance Rho n of 5-9 Ohm-cm, diameter of 48-70 mm and thickness of 175-185 microns, is adopted; silicon piece diffusion is conducted, and double-surface once diffusion is carried out at temperature of 1250 DEG C; the diffusion piece detection is carried out; phosphorosilicate glass and borosilicate glass are used for absorption, the temperature is slowly lowered from 1250 DEG C to 1050 DEG C,the speed rate is 1 DEG C per minute, and isothermal absorption is carried out for 2-3 h; slow temperature reduction is continued till furnace temperature is reduced to 600 DEG C, then furnace delivery is carried out, and minority carrier lifetime Tao p is caused to reach 12-16 Mu S; platinum diffusion is carried out at low temperature so that the minority carrier lifetime Tao p is controlled to be 4-6 Mu S; 12 Mev electron irradiation is carried out so that the minority carrier lifetime Tao p of a base region is 0.9-1.1 Mu S; the two surfaces of the silicon piece are plated with titanium-nickel-gold by means of vapor deposition and then undergo table-board spray sand molding, desanding, cleaning, corrosion, passivation protection, intermediate test, shell arrangement and packaging, and after tests testify qualification, the finished product is produced.
Owner:JINZHOU SHENGHE POWER ELECTRONICS

Voltage conversion circuit, method and multi-phase parallel power supply system

Embodiments of the present invention provide a voltage conversion circuit, a method, and a multi-phase parallel power supply system. The voltage conversion circuit of the present invention provides a frequency-controllable feedback ripple signal through the feedback circuit, so that the operating frequency of the voltage conversion circuit in this implementation can be controlled, which can meet the frequency requirements of the load, and the hysteresis mode does not need compensation and has a fast response speed. The frequency is fixed, so the voltage conversion circuit of this embodiment can be applied to a multi-phase parallel power supply system to meet the application scenario of a large load current.
Owner:HUAWEI TECH CO LTD

Miniaturized waveguide component

InactiveCN108242585ASmall sizeReduce size and volumeWaveguidesMiniaturizationWaveguide
The invention relates to a miniaturized waveguide component comprising a waveguide and a cable fixed on a second wide side thereof. A waveguide cover is assembled at the top end inside the waveguide.The waveguide is filled with a dielectric material therein. A tuning component is arranged on a first wide side of the waveguide. A probe is fixed on a core wire inside the cable. According to the invention, as the waveguide is filled with the dielectric material therein, the size of the waveguide opening can be reduced while the transmission frequency range is ensured not to be reduced, therefore, the overall size and occupation volume of the waveguide component are substantially reduced, the installation of the entire waveguide component in a narrow space is facilitated, and the weight of the system can also be reduced.
Owner:XIAN ELITE ELECTRONICS IND

Generating device and method of large-amplitude ultra-high speed synchronization pulse

The invention discloses a generating device of a large-amplitude ultra-high speed synchronization pulse. The generating device of the large-amplitude ultra-high speed synchronization pulse comprises an input signal shaping circuit and a synchronization pulse generating circuit, wherein the input signal shaping circuit is used for shaping input trigger pulse signal to output low voltage positive pole emitter coupling logic (LVPECL) reference level signal, and the synchronization pulse generating circuit is used for generating the large-amplitude ultra-high speed synchronization pulse with the LVPECL reference level signal as trigger signal. No transistor with an extremely high working voltage is needed in the generating device and method of a large-amplitude ultra-high speed synchronization pulse, therefore, voltage demand on a direct current voltage source is not high. Key functions of the generating device and method of a large-amplitude ultra-high speed synchronization pulse is achieved by a multilevel broadband transistor circuit which can send out positive pulse and negative pulse with pulse front smaller than 200ps and amplitude close to 15V. Meanwhile, compared with input synchronization pulse, delaying time shake of output synchronization pulse is small and smaller than 20ps.
Owner:UNIV OF SCI & TECH OF CHINA

A frequency-tunable ultra-low frequency mechanical antenna structure

The invention discloses a frequency-adjustable ultra-low frequency mechanical antenna structure, belonging to the technical field of ultra-low frequency communication. The antenna structure comprises a static magnetic field generating module for generating a static magnetic field and a cutting static magnetic field generating module for cutting the static magnetic field generating module to generate a time-varying electromagnetic field. The magnetic field module, the static magnetic field generation module includes a motor, a plurality of permanent magnets, a fixed rotating motor and a support frame of the plurality of permanent magnets; the support frame is arranged outside the motor; the plurality of permanent magnets are evenly arranged on the outer surface of the support frame, cutting The static magnetic field module includes a disc, a disc with sawtooth, and a control switch that controls the change of the sawtooth length of the disc and drives the movement of the disc. The number of teeth of the sawtooth disc is the ratio of the frequency of the time-varying magnetic field to the operating frequency of the rotating motor. The movement mode, while minimizing the weakening of the magnetic induction intensity, increases the frequency of electromagnetic waves generated by the mechanical antenna to meet the frequency requirements during the transmission process.
Owner:DALIAN JIAOTONG UNIVERSITY

Method for obtaining anti-interference signal of satellite navigation receiver

The invention relates to the technical field of satellite navigation, in particular to a method for obtaining an anti-interference signal of a satellite navigation receiver. The method comprises steps: preprocessing the signal sent by the antenna array to obtain an intermediate frequency signal containing an interference signal which is not completely filtered; wherein the intermediate frequency signals are respectively used as inputs of a space-time domain algorithm and a power inversion algorithm to obtain corresponding output results; and multiplying the result output by the power inversionalgorithm by the result output by the space-time domain algorithm to obtain an anti-interference signal, namely a signal obtained by the satellite navigation receiver. According to the method, a space-time domain algorithm and a power inversion algorithm are combined, and when the signals sent by the antenna array to the satellite navigation receiver contain pulse interference, broadband interference and weak interference signals, the interference signals can be suppressed by the algorithm, so that the quality of the signals received by the satellite navigation receiver is improved.
Owner:ANHUI SUN CREATE ELECTRONICS

A Method of Correcting the Natural Frequency of Aeroengine Fan Blades

The invention discloses a correction method of inherent frequency of aeroengine fan blades. The correction method comprises the following steps: I, determining an arrangement mode of whole blades, determining a frequency difference between adjacent blades, determining an arrangement position of paired blades with different frequency differences, and determining the maximum frequency difference ofthe whole blades, thereby determining a requirement for frequency distribution for the whole blades of a fan rotor; II, calculating an inherent vibration frequency value of the blades; III, carrying out selection and judgment on frequency values of profile grouping calculation according to an arrangement requirement for frequency selection of a single blade and a frequency difference value of adjacent blades to find out a group meeting the frequency arrangement requirement; and IV, adjusting the contour thickness of a corresponding section of the profile of a blade body to realize the frequency selection requirement of the whole blades.
Owner:AECC AVIATION POWER CO LTD

Grid-connected control method of inverter based on fuzzy control and virtual synchronous generator

The invention relates to an inverter grid-connection control method based on fuzzy control and a virtual synchronous generator. The method comprises the following steps: S1, obtaining a phase angle and potential of the virtual synchronous generator based on a virtual synchronous generator technique according to inverter side output voltage, inverter side output current and grid-connection voltage; S2, obtaining reference current of a current loop based on a proportional-integral control voltage feedback loop according to the potential of the virtual synchronous generator obtained in the step S1 and collected filter capacitor voltage; S3, obtaining three-phase modulation wave based on fuzzy control and the proportional-integral control voltage feedback loop according to the reference current of the current loop obtained by the step S2 and collected filter capacitor current; and S4, comparing the three-phase modulation wave with carrier wave to obtain six switching signals and controlling switching-off and switching-on of an inverter. Compared with the prior art, the stable speed of a system is improved under the premise of ensuring system stability, so that the system has better performance.
Owner:SHANGHAI UNIVERSITY OF ELECTRIC POWER
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