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

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.

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.

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.

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.

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.

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.

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.

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.