32results about How to "Low frequency" patented technology

A zipper for a reclosable bag including an elongated groove profile having two arms which form a general U-shape to define an opening to a channel, and an elongated rib profile opposing the groove profile, wherein a plurality of first segments of the rib profile alternate with a plurality of second segments of the rib profile to create a structural discontinuity along a length thereof, wherein during interlocking the groove and rib profiles, an audible clicking sound of at least 50 dB on average is created during opening and closing.

A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

The invention discloses a broadband active inductor with high Q values and a coarsely tunable and finely tunable inductance value. The broadband active inductor comprises a first transconductance unit (1), a modulation unit (2), a second transconductance unit (3), a third transconductance unit (4), a fourth transconductance unit (5), a first tunable bias circuit (6), a second tunable bias circuit (7), a third tunable bias circuit (8) and a fourth tunable bias circuit (9). The modulation unit is connected with the first transconductance unit and is used for increasing the Q values and bandwidth of the active inductor. The first transconductance unit, the modulation unit and the second transconductance unit form a master circuit. The third transconductance unit and the fourth transconductance unit form a slave circuit. The master circuit and the slave circuit are connected in parallel. The equivalent capacitance for synthesizing the inductance in the whole circuit is increased, so the inductance value of the active inductor is improved. According to the active inductor, the high Q peaks of the active inductor under different frequencies are realized, the Q peaks can be tuned, and the inductance value of the active inductor is coarsely tuned and finely tuned.

A self-resetting frictional energy-dissipating support based on a shape memory alloy, comprising a first channel steel (1) and a second channel steel (2), the outer ends of the first channel steel (1) and the second channel steel (2) are respectively A round pipe (7) and a connecting plate (8) are connected in sequence; the opening of the first channel steel (1) is downward, and the opening of the second channel steel (2) is upward, and the two press the contact surface through the connecting piece (4) to provide Friction force; the left and right sides of the flange of the first channel steel (1) are respectively provided with four first bolts (5) equidistantly distributed, and the left and right sides of the flange of the second channel steel (2) are respectively provided with four second bolts ( 5‑1), the second bolts (5‑1) are symmetrically arranged in pairs relative to the central axis of the second channel steel (2); the shape memory is used between the first bolts (5) and the corresponding second bolts (5‑1) Alloy wires (3) are connected. The invention has simple structure, stable energy consumption performance, almost no residual deformation after unloading, and is easy to replace.

The invention discloses a VSG control method based on a dynamic droop coefficient. Based on a synchronous inverter scheme, by analyzing the steady-state and dynamic characteristics of a VSG and selecting an active frequency droop coefficient and a reactive voltage droop coefficient as adjustment objects, a VSG control method based on dynamic droop coefficient adjustment is designed to make the droop coefficient of the VSG adaptively vary with a cosine function in the event of load fluctuations in an off-grid operation mode. The VSG control method achieves a small frequency and voltage variation range and short response time, thereby ensuring system stability.

The invention discloses a micro-grid coordination control device based on particle swarm self-optimization PID droop control. The device comprises a photovoltaic power generation droop control selection module, a wind power generation droop control selection module, a storage battery droop control selection module, a fuel cell droop control selection module, a photovoltaic power generation PSO self-optimizing PID droop control module, a photovoltaic power generation constant power control module, a wind power generation PSO self-optimization PID droop control module, a wind power generation constant power control module, a storage battery PSO self-optimization PID droop control module, a fuel cell PSO self-optimization PID droop control module and a storage battery charging control module.Each PSO self-optimizing PID droop control module internally comprises a frequency PID droop controller and a voltage PID droop controller. The micro-grid coordination control device realizes automatic conversion of each distributed power supply as a master power supply and a slave power supply, and effectively stabilizes voltage and frequency fluctuation of the micro-grid.

The invention discloses a quick detecting method for a harmonic wave of an electric power system, and particularly relates to a method for detecting phase and amplitude of signals with different frequencies in the electric power system. The method comprises the following steps of (1), acquiring sampling points of which the number is at least two times of that of the harmonic waves through using two times of highest multiplied frequency as a sampling rate; (2), constructing a sine signal and a cosine signal which correspond with each harmonic wave frequency; (3), calculating a harmonic wave detecting parameter through fitting the coefficient before each sine item and cosine item; and (4), combining the coefficients in front of the sine item and the cosine item with the same frequency for obtaining the amplitude and the phase of the harmonic wave with each frequency. Compared with the prior art, the quick detecting method is advantageous in that a small volume of data are required; a result can be calculated just through the data with length of one half of that of a fundamental frequency signal; relative to an FFT (fast Fourier transform) method, a problem of frequency leakage can be prevented; and the method is compatible with clutter interference to a certain extent.

The invention discloses an ultrahigh-frequency metal RFID (radio frequency identification) signboard, which sequentially comprises a metal signboard, a first double-faced adhesive tape layer, an antenna grounding layer, a second double-faced adhesive tape layer, an insulating medium layer, a third double-faced adhesive tape layer, an antenna chip layer and a fourth double-faced adhesive tape layer from top to bottom, and is characterized in that the metal signboard is adhered to the antenna grounding layer through the first double-faced adhesive tape layer; the antenna grounding layer and the antenna chip layer are separated by filling an insulating medium layer, the antenna chip layer is adhered to a managed object through a fourth double-faced adhesive tape layer, the microstrip antenna is characterized in that the antenna grounding layer and the antenna chip layer are conducted through a side face conduction layer to form a microstrip antenna structure, a chip is arranged at the bottom of the microstrip antenna structure, and the antenna grounding layer and the antenna chip layer are connected through a second double-faced adhesive tape layer. And the metal signboard is conducted with the antenna grounding layer at the upper part of the microstrip antenna structure. By means of the mode, holes or excitation holes do not need to be formed, the integrity of the metal layer is guaranteed, and meanwhile the impact resistance of the metal layer is greatly improved.

The invention discloses a radio frequency front-end control circuit, a control method thereof, a radio frequency front-end control chip, a system, a storage medium and a terminal. The radio frequencyfront-end control circuit comprises a plurality of driving devices connected in parallel and used for accessing a driving control signal, wherein the output ends of the driving devices output radio frequency control signals, and the radio frequency control signals are used for controlling a radio frequency front end; and a plurality of delay elements which are respectively coupled with the controlend of each driving device, wherein a driving control signal is input to the control end of each driving device through the delay element coupled with the driving device, and the delay time lengths of the delay elements coupled with the control ends of the plurality of driving devices are sequentially increased. According to the technical scheme of the invention, the EMI of the RF device can be reduced more effectively.

The invention provides a buffering device. The buffering device comprises a shell, a plurality of buffering pipes, an elastic part, a supporting piece and an elastic supporting part; a plurality of similar annular grooves are formed in the hole walls of the buffering pipes, and a plurality of gaps formed in the axial directions of the buffering pipes are formed in the buffering pipes; the elastic part is arranged in the accommodating cavity; a plurality of ring-like bulges are arranged on the outer wall surface of each supporting column; the elastic supporting part is arranged in a connecting hole and located between the shell and the supporting columns; each supporting column comprises a connecting section, a protruding section and a supporting tail section which are sequentially connected; and the lengths of the supporting tail sections of the multiple supporting columns are at least two. According to the buffering device, due to the fact that the lengths of the supporting tail sections in the supporting columns are different, the protruding sections on the different supporting columns have phase differences; the resistances borne by the different supporting columns are different; therefore the load-displacement curve of the structure is changed through the combination of the different supporting columns; and the specific damping coefficient of the buffer device is greatly improved to enhance the buffering performance of the structure.