306 results about "Differential coefficient" patented technology

Provided are an envelope processor 103, for obtaining an envelope for a detected signal; a FFT unit 104, for converting the envelope into a frequency spectrum; a peak detector 105, for smoothing the frequency spectrum by calculating a moving average, for further performing smoothing and differentiation for the spectrum, and detecting, as peaks, frequency points at which a sign of a differential coefficient is changed from positive to negative, for extracting peaks having a predetermined threshold value or greater, and for sorting the extracted peaks and detecting upper peaks; and a diagnosis processor T, for diagnosing an abnormality based on the detected peaks.

An abnormality diagnosis system for machinery comprises an envelope processing section (103) for determining the envelope of a detection signal, an FFT section (104) for converting the envelope into a frequency spectrum, a peak detecting unit (105) in which the frequency spectrum is smoothed by the moving average method, the resultant spectrum is subjected to a smoothed differentiation, frequency points at which the sign of differential coefficient changes from positive to negative are detected as peaks, peaks higher a predetermined threshold are extracted and sorted, and the higher ones are detected as peaks, and a diagnosis section (T) for performing abnormality diagnosis on the basis of the detected peaks.

The invention relates to a PMSM servo system control method based on fuzzy and active disturbance rejection control. A position signal is given by a differential tracker to arrange a transition process so that the contradiction between rapidness and overshoot of a system is solved, and uncertainty, friction torques and external disturbance due to modeling errors of the system are observed via an expansion state observer; according to the error between the differentials generated by the differential tracker and state variation generated by the expansion state observer, a fuzzy inference rule is obtained with application of experimental experience of technical staff, so that a fuzzy rule control table of an error proportion coefficient, a differential coefficient and an integration coefficient is established; accurate control amount is obtained after de-fuzzification, so that parameter self-adaptive adjustment of a nonlinear error feedback control law is realized; and compensation amounts of the nonlinear error feedback control law and the expansion state observer to the total disturbance forms the control amount, thereby realizing optimal control for an controlled object. The method of the invention improves both tracking precision and disturbance rejection capability of the system.

The invention provides a driving circuit and a driving method applied to a flyback-type converter and a quasi-resonant soft-switching flyback-type converter applying the same. According to a driving circuit applied to the flyback-type converter, differential coefficient of the drain-source voltage of a main power switch tube in the flyback-type converter is worked out by a differential circuit, thus leading the time when the drain-source voltage achieves valley floor to correspond to the time when the differential voltage passes the zero point in positive direction. A valley floor voltage detecting circuit is connected with the differential circuit and receives a differential voltage signal; when the drain-source voltage of the main power switch tube achieves the valley floor, a valley floor control signal is output, thus controlling the driving circuit to drive the main power switch tube, and further exactly realizing the aim of conducting the valley floor of the main power switch tube. By adopting the driving circuit, the aim of controlling a quasi-resonant soft switch of the main power switch tube is realized precisely, the driving circuit of the flyback-type converter is optimized so that the controlling effect and the reliability are greatly improved, and the realizing cost is reduced.

The invention provides a voice noise reduction method for a conference terminal based on the neural network model. The method comprises steps that S1, an audio file is collected by the conference terminal device to generate a digital audio signal in the time domain; S2, the digital audio signal is framed, and short-time Fourier transform is performed; S3, the amplitude spectrum of the frequency domain is mapped into a frequency band, and a Mel-frequency cepstral coefficient is further solved; S4, first-order and second-order differential coefficients are calculated through utilizing the Mel-frequency cepstral coefficient, a pitch correlation coefficient is calculated on each frequency band, and pitch period features and VAD features are further extracted; S5, input characteristic parameters of an audio are used as the input of the neural network model, the neural network is trained offline, the frequency band gain generating the noise reduction speech is learned, and the trained weightis solidified; S6, the neural network model is utilized to learn, the frequency band gain is generated, the outputted frequency band gain is mapped to the spectrum, the phase information is added, and a noise reduction speech signal is reduced through inverse Fourier transform. The method is advantaged in that real-time noise reduction can be achieved.

A carbon fiber composite material including an elastomer and 15 to 50 vol % of carbon nanofibers dispersed in the elastomer. The elastomer includes an unsaturated bond or a group exhibiting affinity to the carbon nanofibers, and the carbon nanofibers has an average diameter of 0.7 to 15 nm and an average length of 0.5 to 100 micrometers. The carbon fiber composite material has an average coefficient of linear expansion of 100 ppm/K or less and a differential coefficient of linear expansion of less than 120 ppm/K at −80 to +300° C.

The invention relates to a method of controlling running of a modularized multi-level converter in a low frequency model, which belongs to the technical field of controlling multi-level power electronic converters. The method comprises the following steps: setting high frequency common mode voltage and high frequency ring current both required to be superimposed, revising a switching function of a submodule and bridge arm current, obtaining an expression of capacitance voltage differential coefficient of the submodule according to volt-ampere characteristics of capacitance of the submodule, and in order to allow the capacitance voltage of the submodule to only have high-frequency component, assuming high frequency common mode voltage is known to obtain a expression of the high frequency circular current; comparing a running frequency with a critical frequency to obtain frequency model selection signals, combining an energy control and a circular current control of a phase unit of the modularized multi-level converter, determining whether the high frequency common mode voltage and the high frequency circular current are required to be superimposed to an original instruction or not according to the frequency model selection signals, and generating voltage required to be superimposed in the bridge arm of the phase unit of the high frequency circular current by controlling. The method is easy to realize and strong in universality, and provides reference for low frequency application of the modularized multi-level converter.

This invention relates to a method for controlling charging of storage batteries with gas sensors, which tests oxygen content or gas pressure in the internal gas of the battery with a gas sensor or an outer pressure sensor then uses a differential coefficient method to compute the variety rate of the oxygen or gas pressure to decide its charge state to further determine a charging strategy, which is suitable for Ni-base watercourse batteries.

The invention provides a method and a system for self-adjusting fuzzy PID (Proportion Integration Differentiation) parameters in a furnace temperature control system. The method comprises the following steps: selecting and quantifying variables in a PID controller and finding out a fuzzy relation of three PID control parameters including a proportionality coefficient KP, an integral coefficient KI and a differential coefficient KD , and system deviation e and a deviation varying rate ec; establishing a fuzzy relation table; and carrying out online modification on the three parameters by a fuzzy control method. The system corresponds to the method. After PID parameter online fuzzy self-adjustment is carried out, a normal working state is automatically switched, and a PID parameter adjusting process is automatically started when system performances are changed and the readjusted PID parameters so that the system has the better control quality.

The invention discloses an ultra high-voltage alternating current transmission line protection method based on an all-component differential coefficient matrix, comprising the following steps that the fundamental frequency electric amount on both ends of an ultra high-voltage alternating current transmission line is measured; the positive, negative and zero sequence current amount on the other end is calculated from that on one end of the line with a long line equation; the fundamental frequency current amount on the other end is calculated through a symmetrical component method; and then a differential coefficient matrix is calculated. A fault type is judged according to the values of all elements of the differential coefficient matrix, and a fault phase is enabled to be correctly tripped. The method is applicable to protecting the whole fault process of the ultra high-voltage alternating current transmission line; and particularly when the ultra high-voltage alternating current transmission line has a single-phase high-resistance grounding short-circuit fault, the method can accurately identify and correctly trip the fault phase, and circuit breakers on both ends of other two normal phase lines are reliable without working.

The magnetic material for magnetic refrigeration of the present invention is characterized by exhibiting, in a certain temperature region, preferably, only in part of a temperature region from 200 K to 350 K, an inflection point at which a second order differential coefficient of a magnetization curve changes from positive to negative with respect to a magnetic field, within the range of this magnetic field formed using a permanent magnet unit. This magnetic material of the present invention can generate a low temperature by using a relatively low magnetic field, by transferring the entropy between the electron spin system and the lattice system near the temperature at which an inflection point appears on the magnetization curve. Examples of the magnetic material meeting this condition are La(Fe,Si)₁₃, (Hf,Ta)Fe₂, (Ti,Sc)Fe₂, and (Nb,Mo)Fe₂, each containing 50 to 60 atomic % of transition metals such as Fe.

A synchronizing apparatus, which controls, by a PLL circuit, a sampling clock to be used to sample input data and synchronizes a phase of the sampling clock with a target phase that is desirable for sampling the input data, includes: phase error detection means for detecting a phase error from sampling data and the sampling clock, the sampling data being sampled from the input data at timing of the sampling clock; frequency error detection means for detecting, based on a differential coefficient obtained as a result of detecting the phase error, a frequency error; and frequency correction means for correcting a frequency of the sampling clock such that the detected frequency error becomes close to zero by adding a frequency correction value to an integral term of a loop filter of the PLL circuit, the frequency correction value being calculated based on the frequency error.

The invention discloses an impedance self-adapting motion control method based on a rehabilitation training robot. The method is characterized in that: an online recognizer calculates an equivalent quality parameter Mh, an equivalent damping parameter Bh and an equivalent rigidity parameter Kh of a limb according to acting force and position of the limb collected by a force sensor and a position sensor, and corrects a proportional factor KP, an integral coefficient KI and a differential coefficient KD of a proportional-differential-integral controller according to the variation of the parameters; and a motor power signal output by the proportional-differential-integral controller is converted into a driving signal of a torque motor for controlling the work of the torque motor. According to the control method, the control flexibility and safety of the rehabilitation training robot can be improved.

The invention provides a quick digital image correlation measurement method based on stochastic parallel gradient descent optimization technology, comprising the following steps of comprehensively considering related parameters such as displacement, differential coefficient and the like of any one point in a speckle field of an object to be measured; and utilizing the stochastic parallel optimization technology to realize quick digital image correlation measurement. In the method, by adopting stochastic parallel disturbance on a deformation parameter, the correlation coefficient is convergentto a global unique extremum, thus obtaining the deformation parameter. The method has a simple principle, can be realized easily, is a DIC (digital image correlation) measurement method with totally new concept, can realize the aim of quickly measuring DIC with high precision and high reliability, and is expected to realize the real-time online measurement on the DIC.

The apparatus is designed for use in enhancing the complex texture details of digital image in real-time. It comprises a memory module, a phase-locking/shift circuit, a fractional order differential mask convolution circuit and a maximum value comparator. In the fractional order differential mask convolution circuit, the operation rules of 8 dedicated algorithm circuits use fractional order differential mask convolution scheme to achieve the spatial filter of digital image fractional order differential coefficient. The invention can be used in HDTV, biomedicine image, bank paper, satellite remote sensing, and creature characteristic graph.

The invention discloses an improved current loop control method for a photovoltaic grid-connected inverter, and belongs to the technical field of solar photovoltaic power generation. The method comprises the following steps that: a voltage feedforward control quantity u1 is obtained through commercial electricity voltage feedforward; 2, a current error [delta]i is obtained through a voltage outer loop control structure; 3, the current error [delta]i is segmented for forming a plurality of current error segments, each current error segment adopts different gains, and a current equivalent voltage duty ratio control quantity u2 is obtained after the current passes through a current inner loop control structure adopting a controller P; and 4, a command value u_order of a switch comparison register is obtained. The control method provided by the invention has the advantages that the realization is simple; complicated integral and differential coefficient setting is not needed; the introduction of virtual orthogonal signals is not needed; time-consuming dp coordinate transformation is avoided; meanwhile, the output current distortion can be effectively reduced; and the resistance capability on electricity grid distortion and harmonic interference is enhanced.

The invention provides a fuzzy control-based special PID (Proportion Integration Differentiation) method for controlling temperature of a plastic extrusion device. By taking the traditional PID control for reference and introducing an algorithm and an implementation mode of fuzzy rules, the method comprises a few important parts such as parameter fuzzification, fuzzy rule reasoning, parameter defuzzification, PID controller and the like. The method comprises the following steps of: calculating the deviation between an actual temperature and a theoretical temperature and current deviation variation speed according to reference input and feedback signals, performing fuzzy reasoning in a fuzzy reasoning device by means of fuzzy experience, performing fuzzification to convert an input value into a membership degree by means of a membership function of an input fuzzy set, outputting a proportion coefficient, an integration coefficient and a differentiation coefficient of a PID controller by the fuzzy reasoning device, and performing PID control by using the coefficients as references of the current controller. By calling the fuzzy rules of the heating and water cooling processes of a plastic extruder, nonlinear effect produced by water vaporizing and cooling in the cooling process can be effectively controlled, the temperature control of the whole main machine meets the requirement of the extrusion temperature, the extrusion quantity of the plastics is stabilized, and the product quality is improved.

The invention relates to a control method for inhibiting the influence on main steam pressure of a boiler caused by that a coal pulverizer is started or stopped, and a rapid control layer of average rotating speed of a coal feeder is added on the basis of three-layer control mode of the original boiler fuel, so that the influence on the main steam pressure of the boiler caused by various operation of the operators is effectively inhibited when in the process that the coal pulverizer is started or stopped. A dynamic feed-forward technique based on the actual differential coefficient is applied to the feed-forward design of a boiler main control system by the method, so that the command of automatically modifying the coal quantity in the boiler can be realized in the process that the coal pulverizer is started or stopped, and the excessive part of coal dust quantity which enters the boiler to be burnt is counteracted due to start grinding, warm grinding or stop grinding in the process of powder extraction, thus ensuring the combustion conditions of the boiler to be stabler and effectively inhibiting the influence on main steam pressure caused by that the coal pulverizer is started or stopped.

It is a challenge to make it possible to produce a resonance suppression effect, and perform a stable control even in a case where a spring rigidity of a shaft significantly varies. The challenge is achieved as follows. In an engine bench system in which an engine 1 to be tested and a dynamometer 2 are coupled together by a coupling shaft 3, and a shaft torque control of the dynamometer is performed, a controller 5 includes: an integral element having an integral coefficient K_I for a deviation (T12r−T12) between a shaft torque command T12r and a measured shaft torque T12; a differential element having a differential coefficient K_D for the measured shaft torque T12; and a proportional element K_P for the measured shaft torque T12. The controller 5 obtains a torque control signal T2 by subtracting the differential element and the proportional element from the integral element. Control parameters (K_I, K_P, K_D, f₁) are determined according to control characteristic parameters (a4, a3, a2, a1) set in a function calculation section 6, inertia moments J1, J2 of the engine and the dynamometer, and spring rigidity K12 of the coupling shaft.

The disclosed multivariable control method for distribution static reactive generator comprises: detecting the access-point voltage and dc-side capacitance voltage to compare with reference value and obtain error, calculating the error and error increment; taking the error and error increment as NN input to train NN and adjust PID controller parameters to obtain modulation parameter and phase difference for the inverter; obtaining the switch control signal. This invention is adaptive.

The invention discloses an ultra-high-voltage transmission line relay protection method based on a break variable differential coefficient matrix. The method includes by utilizing a distributed parameter model, computing three-phase current break variables of the other end of an ultra-high-voltage transmission line by positive, negative and zero-sequence voltage break variables and current break variables of one end of the ultra-high-voltage transmission line and positive, negative and zero-sequence current break variables of the other end of the ultra-high-voltage transmission line by the aid of a symmetrical component method, further computing the break variable differential coefficient matrix, forming protection criterions according to size relationships of elements of the break variable differential coefficient matrix, and distinguishing fault phases of the ultra-high-voltage transmission line. The distributed parameter model is used as a physical model and unaffected by distributed capacitance current, and the method is applicable to any voltage classes and in particular to ultra-high-voltage transmission lines.

The invention discloses an orbit expansion based multi-robot tracing formulation control method, comprising the following steps of: a) for a group of target orbit in a plane, expanding vectors of the target orbit, which point to each point on the orbit along the center of the target orbit, into an orbital cluster equivalent to an orbital function, and determining the movable range of robots; b) calculating tracing error by virtue of the orbital function, and designing the virtual angular velocity of the robots to ensure the tracing error to meet design requirements; c) calculating the generalized arc length and differential coefficient of the generalized arc length when the robots move along the orbit, by virtue of the orbital function and the target orbit, and designing the control force of the robots by virtue of neighbor information obtained by communication to realize formulation; d) calculating the error between the real angular velocity and the virtual angular velocity, and designing the control moment of force of the robot to complete tracing; and e) completing motion control on the robots by virtue of a servo system. The orbit expansion based multi-robot tracing formulation control method disclosed by the invention is especially applicable to nonholonomic constraint dynamic robots and simple and convexly- closed orbits. The method is simple and reliable, has higher accuracy and can be applied to multi-robot optimized information acquisition and the like.