53results about How to "Reduce nonlinearity" patented technology

The present invention relates to a multi-core optical fiber having a structure for reducing transmission loss and nonlinearity. The multi-core optical fiber comprises plural cores extending along a center axis direction, and a cladding surrounding the peripheries of the plural cores. The cladding is comprised of silica glass doped with fluorine, and each of the plural cores is comprised of silica glass doped with chlorine or pure silica glass.

The invention relates to a method for measuring the phase fractions of oil-water two-phase flows based on an ultrasonic attenuation mechanism model. According to the method, one main receiving sensor and six auxiliary ultrasonic receiving sensors are adopted. The method comprises the following steps: setting a detection signal of the main receiving sensor as V2, respectively setting detection signals of the six auxiliary ultrasonic receiving sensors as V3......V8, and calculating the ultrasonic intensity attenuation of the detection signals V2, V3......V8 and a drive signal V1; calculating the sum of a total ultrasonic attenuation coefficient of an oil-water two-phase-flow fluid and the ultrasonic diffusion attenuation amount of each auxiliary ultrasonic receiving sensor; detecting transit time from a time point when the drive signal is emitted by a signal emitting sensor to a time point when the signal is received by the main receiving sensor; calculating an oil-water two-phase scattering parameter; and calculating each phase fraction of the oil-water two-phase flows. By virtue of the method, the estimation precision of the moisture content can be increased.

The invention provides a safety constraint economic dispatching method for embedded reactive power and voltage, and belongs to the field of electric power system safety constraint economic dispatching. According to the method, first an optimal power flow model of safety constraint economic dispatching formed by an objective function and a constraint condition is built; after the model is iteratively solved, a per unit error is checked for all branch lines; if a line exists which does not meet the per unit error, a power flow equation constraint is updated, iteration of a next time is performedtill all the lines meet the per unit error, the model converges, iteration ends, and a whole set of electric power system safety constraint economic dispatching scheme containing node voltage amplitude, a voltage phase angle, unit active power output and reactive power output is obtained. The safety constraint economic dispatching method for embedded reactive power and voltage can maximally meetelectric power system economic operation requirements, and reduce electric power system operation cost; and is high in precision, is good in convergence, and has very high practical application value.

The invention discloses an acute spinal cord injury animal model modeling impactor, which is characterized by comprising a bracket, a lever, a guide rail, a probe and a relay device for driving the lever. A support point of the lever is arranged on the bracket; one end of the lever is provided with a sucking disc, the other end is connected with the upper end of the probe; the relay device and the guide rail are both fixed on the bracket along a vertical direction; the relay device is arranged above the sucking disc; the probe is arranged in the guide rail along the vertical direction; a return spring is arranged between the upper end of the guide rail and the upper end of the probe; the relay device comprises a multiple-turn coil and an iron core; the iron core is inserted in the multiple-turn coil; and the terminal of the multiple-turn coil is connected with a controllable current output interface of an external circuit. The impact degree and time of the impactor can be controlled, the impact position is more correct, and the repeatability of the impact operation is strong.

An analog sample-and-hold switch has parallel branches extending from an input node to an output node connected to a hold capacitor, each branch having a PMOS signal switch FET in series with a PMOS dummy FET. A sample clock controls on-off switching of the PMOS signal switch FETs, and an inverse of the sample clock controls a complementary on-off switching of the PMOS dummy FETs. A bias sequencer circuit biases the PMOS signal switch FETs and biases the PMOS dummy FETs, in a complementary manner, synchronous with their respective on-off states. The on-off switching of the PMOS dummy FETs injects charge cancelling a charge injection by the PMOS signal switch FETs, and injects glitches cancelling glitches injected by the PMOS signal switch FETs.

The invention discloses a method for improving a phase-locked loop based on an adaptive variable gain for realizing fast response. The method comprises the following steps: sampling a grid three-phase voltage signal, and converting a three-phase voltage into a two-phase voltage (the formula is as shown in the specification) through Clark transform and Park transform; obtaining an open-loop transfer function of the phase-locked loop containing a nonlinear phase discrimination link according to a phase-locked loop (SRF-PLL) nonlinear mathematic model based on a synchronous coordinate system; obtaining the relationship between open loop cut-off frequency (the formula is as shown in the specification) and an input deviation (the formula is as shown in the specification) through the transfer function, and constructing a variable gain function containing an amplitude (the formula is as shown in the specification), a nonlinear system deviation (the formula is as shown in the specification) and linear system deviation (the formula is as shown in the specification) to reduce the nonlinearity of the system; reforming the traditional PI controller through the variable gain function, and designing an adaptive integral gain (the formula is as shown in the specification) to replace the original (the formula is as shown in the specification) so as to obtain an adaptive variable gain phase-locked loop system; and performing time domain analysis on a closed loop equivalent linear system to accomplish the integration of system parameters. According to the method disclosed by the invention, the variable gain control is constructed to reduce the degree of nonlinearity of the open-loop system, reduce the coupling relationship between the angular velocity and the angle, shorten the dynamic transition time of the phase-locked loop and performs dynamic response contrastive analysis on the traditional phase-locked loop system and the improved phase-locked loop system by using a simulation platform.

The invention provides a real-time positioning method and device fusing laser radar and IMU sensor information, and the method comprises the steps: taking unscented Kalman filtering as a frame, carrying out the motion prediction of an unmanned platform through the data of a high-frequency inertial measurement unit, and caching the data; after the point cloud matching module receives the laser radar data with the timestamp, using the predicted pose as prior information, performing matching based on normal distribution transformation and a known point cloud map, and obtaining global positioning information with delay; using the positioning information for updating unscented Kalman filtering at the moment of the laser radar timestamp, calibrating the prediction error of the inertial measurement unit, and using the cached high-frequency inertial measurement unit data for performing re-prediction based on the positioning information, so that the low-delay and high-frequency positioning effect is realized. According to the method, high-frequency and low-delay real-time positioning can be realized, and a better control effect is brought.

A high speed high resolution heterodyne interferometric method and system are provided. The invention uses two spatially separated beams with slightly different frequencies and has two measurement signals with opposite Doppler shift. The switching circuit selects one of the two measurement signals for displacement measurement according to the direction and speed of the target movement. In this invention, the measurement is insensitive to the thermal variation; the periodic nonlinearity is essentially eliminated by using two spatially separated beams; the measurable target speed of the interferometer is no longer limited by the beat frequency of the laser source.

The invention discloses a silicon carbide MEMS temperature and pressure composite sensor chip and a preparation method thereof. The sensor chip comprises a peripheral pressure measuring unit and a central temperature measuring unit; the pressure measuring unit comprises a silicon carbide substrate with a convex island, and a circular back cavity is etched on the back surface to form a pressure sensitive diaphragm; wherein the convex islands and the pressure sensitive membrane form a membrane island structure; four piezoresistive strips are symmetrically arranged outside the convex island and inside the pressure sensitive diaphragm along the circumference of the root of the pressure sensitive diaphragm; the temperature measuring unit comprises a substrate convex island and a thin film thermocouple arranged on the substrate convex island; When pressure acts on the chip, the pressure measuring unit converts the pressure into an electric signal through a semiconductor piezoresistive effect and a Wheatstone bridge and outputs the electric signal. Meanwhile, the temperature measuring unit converts the temperature into thermoelectric force through the Seebeck effect of a metal film thermocouple and outputs the thermoelectric force, so that real-time detection of the pressure and the temperature at the high temperature is completed. The sensor chip has the advantages of high temperature resistance, miniaturization, high sensitivity, good stability and the like.

The invention relates to a gradient coil design method for a biomedical imaging system and a gradient coil. The gradient coil design method for the biomedical imaging system comprises the following steps that a, a non-developable curved surface serves as a gradient coil bearing surface of a gradient coil, and the gradient coil design method comprises the following steps that a, dividing and dispersing the non-developable gradient coil bearing surface; b, distributing at least two wires which are connected with each other on the bearing surface of the non-developable gradient coil after subdivision and dispersion; c, driving the wire by adopting a driving circuit, determining the spatial position of the wire, and obtaining the configuration of the wire in a three-dimensional space; and d, processing a gradient coil according to the configuration of the wire. According to the invention, the gradient coil bearing surface is expanded from an expandable surface (a cylinder or an elliptic cylinder) to an unexpandable curved surface, various application requirements of a magnetic biological imaging system are met, and the imaging quality is improved.

The invention discloses a user side comprehensive energy system optimal configuration method, and belongs to the field of comprehensive energy system optimal configuration. The method comprises the following steps: S1, building an all-working-condition energy conversion model of equipment according to the energy structure of the southwest region and the characteristics that the efficiency of operation equipment changes along with the environment and output, the full-working-condition energy conversion model comprises a natural gas internal combustion engine, a gas turbine, a hot water type gasboiler, a hot water type waste heat boiler, an absorption refrigerator, a photovoltaic and wind power generation system, a water source heat pump and an energy storage device. Aiming at the current energy situation of a specific region in the southwest region, according to an all-working-condition energy consumption scene with a changed conversion efficiency coefficient, an all-working-conditionmathematical model of each part of equipment is established, optimal configuration of the user-side comprehensive energy system is carried out, the precision of the optimal configuration model is high, and the improvement of the accuracy and rationality of system planning is facilitated.