11results about How to "Reduce non-linearity" patented technology

A phase-locked loop (PLL) circuit, an operating method thereof, and a sub-range control circuit are provided. The PLL circuit includes a time-to-digital converter (TDC), a loop filter, a digitally controlled oscillator (DCO), a feedback circuit, a sigma-delta modulator (SDM), and a prediction circuit. The TDC includes a phase detector and a processing circuit. The phase detector generates a charging current signal according to an input frequency signal and a feedback signal. The processing circuit limits a voltage level corresponding to the charging current signal within a certain voltage range according to a prediction signal to generate a digital output. The loop filter is coupled to the TDC to perform a low-pass filtering operation according to the digital output. The DCO generates a DCO frequency signal according to an output of the loop filter. The feedback circuit generates the feedback signal according to the DCO frequency signal. The sigma-delta modulator (SDM) generates a phase signal representing accumulated phase shift information to the prediction circuit according to information of the feedback circuit and fractional frequency information. The prediction circuit generates the prediction signal according to the phase signal.

The application discloses a parallel hole damping-spiral tube inerter underwater damping device and belongs to the technical field of underwater vibration control. The device comprises an upper shell, a lower shell, a damping spring, an open small hole damping and an open fluid inerter. The upper shell and the lower shell are two parts in relative sliding. The damping spring and the open small hole damping are assembled in parallel to form an integral body, which together constitutes an open spring damping. The open spring damping and the open fluid inerter are connected in parallel, and the upper and lower ends of the two are respectively fixed to the upper shell and the lower shell. The open small hole damping and the open fluid inerter are both installed in the upper shell and the lower shell. The application adopts a parallel topology structure of inerter, damping and spring. The double spiral pipes and the symmetrical piston rods realize the fluid inerter effect in two directions. The small holes on the damping piston realize the speed-dependent throttling damping. The device has the characteristics of wide frequency vibration isolation, strong static load capacity, symmetrical positive and negative characteristics and deep water environment.

The invention provides an epitaxial structure of a gallium nitride thin film and a preparation method, and relates to the technical field of semiconductors, and the epitaxial structure comprises a substrate, a buffer layer, a GaN thin film, an AlGaN barrier layer and an insulating layer which are sequentially laminated; the insulating layer is provided with a plurality of rectangular gate slots, a first source slot and a second source slot. The bottom of the first source slot and the bottom of the second source slot extend to the bottom of the AlGaN barrier layer. The comb-shaped grid is provided with a plurality of rectangular grid roots matched with the rectangular grid root slots; the width of each rectangular gate heel in the longitudinal direction of the epitaxial structure and the distance between the adjacent rectangular gate heels are constrained by the actual intrinsic transconductivity of the epitaxial structure; when a break-over voltage is applied to the comb-shaped grid electrode, the two-dimensional electron gas layer between the multi-contact pin source electrode and the multi-contact pin drain electrode is conducted, a conductive channel is formed, the stability of source electrode access resistance is improved, the non-linear change of the source electrode along with the current or voltage is reduced, and the linearity of the epitaxial structure is further improved.

This invention belongs to the technical field of pressure generation control and sensor calibration. It discloses a high-pressure gas pressure servo control and calibration measurement device. The device includes an inlet pipe, a pressure reducing valve, a second solenoid valve, a pressure sensor, a pressure chamber, a first solenoid valve, and a high-pressure electric servo valve. The inlet pipe is connected to the pressure reducing valve, which is connected to the first solenoid valve via a pipe. The first solenoid valve is connected to the high-pressure electric servo valve via a pipe, and the high-pressure electric servo valve is connected to the second solenoid valve via a pipe. The second solenoid valve is connected to the pressure chamber via a pipe, and the pressure sensor is connected to the pressure chamber. The pressure chamber is also used to connect a pressure sensor to be measured. This invention controls the pressure within the pressure chamber through the high-pressure electric servo valve, achieving high-precision and high-response pressure control, primarily solving the problem of the lack of real-time inflation / deflation control functionality.

The application discloses an asymmetric parasitic calibration segmented capacitance array, which comprises a positive end capacitance array and a negative end capacitance array, and the capacitance array comprises sampling capacitance, conversion capacitance, calibration capacitance and compensation capacitance; the sampling capacitance adopts simple switch timing, and gain error caused by high segment parasitic capacitance can be eliminated; the conversion capacitance adopts a segmented capacitance array structure, and the number and area of capacitances are reduced; the calibration capacitance is used for calibrating nonlinearity caused by parasitic capacitance of bridging capacitance and parasitic of LSB array; and the compensation capacitance matches the positive end and negative end capacitance arrays. The calibration circuit and the calibration timing sequence thereof are simple in realization and low in power consumption.

The present application relates to a kind of hydraulic swing joint position servo system and its NDOB-SMC control method, first design hydraulic swing joint position servo system, servo valve and the cylinder body of hydraulic cylinder are integrated direct connection design in this system, abandon oil pipe connection, not only structure is more compact, and reduce part interference factor;Second, design a kind of sliding mode control strategy based on nonlinear disturbance observer, combine nonlinear disturbance observer and sliding mode control, give full play to respective advantages, improve the tracking accuracy and response speed of hydraulic swing joint;Finally, the component model library of AMEsim platform is rich and the powerful numerical operation ability of Matlab platform, by creating S-Function interface, the joint simulation of two platforms is realized, and the effectiveness and superiority of the proposed control method are verified.

The invention belongs to the technical field of performance improvement of micro-electro-mechanical accelerometers, and provides a multi-bit micro-electro-mechanical accelerometer. Comprising a meter head sensitive structure, a CV conversion circuit, a first-order control circuit, a multi-bit quantizer, a torquer coefficient module and an acceleration conversion module, and an input acceleration signal and a feedback acceleration signal are subtracted and then input to the meter head sensitive structure; the output end of the gauge head sensitive structure is connected with the input end of the CV conversion circuit; the output end of the CV conversion circuit is connected with the feed-forward input end of the first-order control circuit, and the output end of the first-order control circuit is connected with the input end of the multi-bit quantizer; the output end of the multi-bit quantizer is connected with the feedback input end of the first-order control circuit and the input end of the torquer coefficient module; the output end of the torquer coefficient module is connected with the input end of the acceleration conversion module, the acceleration conversion module outputs feedback acceleration signals, and the front end of the gauge head sensitive structure is provided with multiple pairs of feedback electrodes corresponding to multiple bits.

The invention relates to a polarization-maintaining hollow-core anti-resonance optical fiber suitable for laser transmission and broadband communication, which comprises an elliptical fiber core (1), an outermost sleeve (7) and a cladding area, and is characterized in that the elliptical fiber core (1) is filled with air; the cladding region comprises an x-direction structure and a y-direction structure, the x-direction structure comprises at least one first cladding, the y-direction structure is vertically symmetrical relative to the central axis of the x-direction structure and is divided into an upper half part and a lower half part, and each of the upper half part and the lower half part comprises at least one second cladding; the first cladding comprises a first cladding tube (2), a second nested cladding tube (3) and a third nested cladding tube (4); and the second cladding comprises an internally nested cladding tube (5) and an externally nested cladding tube (6). According to the invention, polarization and low-loss energy transmission can be realized in a 1080nm high-energy transmission wave band, and wide application prospects are realized in the aspects of communication, sensing, high-energy polarization laser transmission and the like.

The invention discloses a hourly runoff combined prediction method based on IRFO-VMD and ITCN-A. The hourly runoff combined prediction method comprises the following steps: collecting runoff data; optimizing the parameters of the VMD by using IRFO, and decomposing the runoff time sequence into K intrinsic mode functions (IMFs) by using the optimized VMD; the method comprises the following steps: extracting dynamic characteristics of a runoff time sequence by adopting phase-space reconstruction PSR, and then dividing runoff data into a training set, a verification set and a test set; and training the ITCN-A model by using the training set and the verification set containing the runoff time sequence dynamic characteristics, and predicting the test set by using the trained model. And analyzing a prediction result of the model by adopting three evaluation indexes including a root mean square error (RMSE), a mean absolute error (MAE) and a mean absolute percentage error (MAPE). According to the method, a good prediction effect is achieved on historical data of different hydrological stations, and the stability of the prediction model and the accuracy of the prediction effect are remarkably improved.

The application claims a high-gain operational amplifier circuit for Sigma-Delta ADC. The circuit comprises a main operational amplifier, a gain-improving auxiliary operational amplifier, a bias circuit and a switched-capacitor common-mode negative feedback circuit. The main operational amplifier serves as the main body of the circuit, has a high gain and a wide bandwidth; the auxiliary operational amplifier improves the output impedance and effectively improves the DC gain of the operational amplifier; the bias circuit is used to provide appropriate DC bias voltage for the main operational amplifier and the auxiliary operational amplifier; the switched-capacitor common-mode negative feedback is used to stabilize the output common-mode voltage. The application uses the auxiliary operational amplifier to improve the gain, ensures a high input-output swing of the operational amplifier, improves the DC gain of the operational amplifier, adopts a symmetrical switched-capacitor common-mode negative feedback, ensures the bandwidth range and reduces the nonlinearity of the circuit.

The application discloses a kind of discrete developable surface construction and optimization method, system, equipment and medium, the method includes: obtaining quadrilateral grid;According to quadrilateral grid, parallel quadrilateral cell in chessboard distribution is constructed inside quadrilateral grid, and establish developable surface geometric model;The constraint of developable surface geometric model includes: having the constraint of chessboard pattern with embedded parallel quadrilateral, equiangular constraint, shape similarity constraint and equidistance constraint;Developable surface geometric model is solved, and discrete developable surface with congruent parallel quadrilateral is obtained;The geometric feature of the discrete developable surface is encoded into uniform plane unit, so that each surface sheet can be processed and formed using the same machining parameter or the same mold set.The application significantly reduces the number of molds and manufacturing complexity, and improves the feasibility of engineering implementation.The application integrates the chessboard pattern construction, equiangular and equidistance geometric constraints and engineering solving process into the same technical system, realizes the complete engineering process from quadrilateral grid to discrete developable surface.The application is suitable for being applied to building curved surface structure and curtain wall unit design, deployable shell and foldable structure modeling, sheet bending and sheet metal forming design, engineering shell and cladding structure design, and assembly type structure manufacturing based on plane sheet, etc.