21 results about "Periodic oscillations" patented technology

The invention discloses an inertial navigation system periodic oscillation suppression method based on time-frequency transformation, and relates to the technical field of underwater navigation, and the method comprises the following steps: S1, modeling an error propagation model of an INS, and defining coordinate systems required by INS navigation, including an inertial coordinate system, a navigation coordinate system and a body coordinate system; based on the INS navigation equation, obtaining an INS error model, and carrying out time domain analysis to obtain an analytical solution of time domain error divergence; s2, designing a time-frequency transformation NTFT, proposing a normal phase time-frequency transformation method, and constructing a complete observation equation; s3, substituting a null method into a calculated longitude and latitude result, and accurately extracting frequency, phase and instantaneous amplitude in inertial navigation longitude and latitude; and S4, establishing a resolving framework of the inertial navigation system periodic oscillation suppression method based on time-frequency transformation, and constructing a negative feedback loop through input gyroscope and acceleration information to suppress periodic errors.

The application discloses a communication-restricted multi-agent tracking control method for trains, which comprises the following steps: S1, for a high-speed train dynamics model, a train formation dynamics model is designed; S2, a non-singular sliding mode surface is designed, which is brought into a dynamics equation, an equivalent control law and a total control law are designed; S3, a fixed threshold strategy is designed based on a control input signal error, and an event trigger condition is constructed; S4, through information interaction of adjacent vehicles, unmeasured states are estimated by using local measurable states, full-state feedback is provided for a controller, and a distributed observer is designed; the application has the beneficial effects that an improved terminal sliding mode surface is designed by using a non-singular terminal sliding mode surface, wherein the non-singular terminal sliding mode surface is a coprime odd number, fraction exponent irreducibility is ensured, periodic oscillation is avoided, and the singularity problem of traditional sliding mode control in time is eliminated by the fraction exponent term.

The invention belongs to the technical field of air compressor efficiency evaluation, and provides an air compressor efficiency evaluation method and system based on decline trend prejudgment, and the method comprises the steps: comprehensively judging whether the high-frequency oscillation of an efficiency signal is caused by a rotating stall cluster or not through the time domain analysis and judgment of high-frequency periodic oscillation and the frequency domain judgment of a characteristic peak; if yes, performing dual-band division of a stall mass oscillation characteristic band and an efficiency decline low-frequency characteristic band; the method comprises the following steps: acquiring a compressor efficiency oscillation and decline composite signal, performing wavelet packet decomposition according to divided dual bands, removing decomposed oscillation characteristic frequency band signals, only retaining efficiency decline characteristic frequency band signals, and reconstructing an oscillation-interference-free pure efficiency decline trend curve through spline interpolation and moving average; and on the basis of the pure efficiency decline trend curve, fitting calculation analysis of the linear / nonlinear decline rate is conducted, and judgment of the efficiency decline trend of the gas compressor is achieved in combination with pure efficiency decline trend curve morphological analysis.

The present application relates to the technical field of fluid control valve, specifically to a pilot pressure reducing valve pilot pressure pipe length optimization design method. The present application uses the force balance equation containing time lag to obtain the critical time lag of the system generating periodic oscillation, then establishes the length constraint equation of the pilot pressure pipe through the relationship between the pipe length and the critical time lag, finally uses the iterative method to obtain the maximum allowable length of the pilot pressure pipe, and then outputs the actual length according to the field installation requirement, which can provide adjustment suggestions for different installation conditions and has wide adaptability. At the same time, the reasonable range of the pilot pressure pipe length can be determined at the design stage, the pilot pressure pipe can be avoided to be replaced repeatedly on site, the installation cost is reduced, and the consistency of the valve is improved.

The application belongs to the technical field of underwater propeller, and discloses a control method for periodic swing of bionic hydrofoil, which controls the hydrofoil to swing according to the following periodic swing rule: each swing period of the periodic swing rule is composed of two half periods which are mirror-symmetric about the center position; each half period is sequentially composed of a recovery stroke and a power stroke, wherein the ratio of the maximum angular velocity of the power stroke to the maximum angular velocity of the recovery stroke, i.e. the speed ratio, satisfies the application. Through the provided periodic motion rule, the rigid impact is eliminated, the residence time of the hydrofoil at the center position is prolonged, the propulsion efficiency and the forward distance are effectively improved, and reliable technical support is provided for the engineering propulsion of rigid hydrofoil.

The invention belongs to the technical field of data analysis, and particularly relates to a running state diagnosis method and system for a constant humidity system, and the method comprises the steps: synchronously obtaining the humidity state of a cab and an engine rotating speed time sequence, carrying out the differential and standardized processing of humidity data, and obtaining a differential result; constructing three core diagnosis indexes, namely a dynamic trajectory entropy, a three-dimensional trajectory circularity and a resonance decoupling index; wherein the dynamic trajectory entropy is used for preliminarily screening abnormal states with high uncertainty; the three-dimensional track circularity is used for distinguishing periodic oscillation and random noise; according to the resonance decoupling index, the engine rotating speed is used as an external reference source, whether a source of periodic fluctuation is a true fault caused by control oscillation in a system or a false fault caused by resonance interference caused by external sources such as an engine is accurately judged through spectral analysis, and finally, through layer-by-layer logic judgment of the three indexes, the resonance decoupling index is obtained. Accurate diagnosis of the state of the constant humidity system is achieved, and misjudgment is effectively avoided.

The application provides a high-speed periodic oscillation flow field measurement method, system, device and medium based on phase locking and synchronous control, wherein the method comprises the following steps: measuring flow field information through a pressure sensor, and acquiring characteristic phases and characteristic values in each cycle of the flow field; a synchronous controller generates a synchronization signal based on the acquired characteristic phases, and sends the synchronization signal to the PIV system and the PSP system; the PIV system and the PSP system collect flow field information under the control of the synchronization signal, and acquire flow field information at different phases in a cycle; and the flow field in a cycle is information-fitted and reconstructed according to the flow field information at different phases in a cycle, and an intuitive flow map of the periodic oscillation flow field is acquired. The application controls the PIV and the PSP to shoot flow images through accurate triggering of different characteristic phases, thereby periodically reconstructing the velocity field and the pressure field of the flow, providing intuitive and profound physical images, and achieving information acquisition of the high-speed oscillation quasi-periodic flow field.

The invention relates to a method and to a circuit arrangement for determining characteristic parameters of an oscillator (OSZ), said method comprising the following steps: comparing (S1) an output signal (x) of the oscillator (OSZ) with a threshold value (x thr) in order to determine a comparison result; generating (S2) a feedback signal (FB) to which one of two different feedback levels (ACC+; ACC-) is applied depending on the determined comparison result; delaying (S3) the generated feedback signal (FB) by a delay time (tD) in order to establish a continuous periodic oscillation of the feedback-coupled oscillator; and determining (S4) the characteristic parameters of the oscillator (OSZ) on the basis of sampled values within a self-oscillation period of a triggered self-oscillation of the oscillator (OSZ).

The application discloses a millimeter wave movable array beam training method based on quantum correlation simulated annealing, and relates to the technical field of wireless communication.The application proposes a quantum correlation simulated annealing (QCSA) algorithm aiming at the high-dimensional, non-convex and strongly coupled beam-array position joint optimization problem caused by the movable array, and adopts an alternating optimization framework to decompose the joint optimization problem into iterative solving of the transmitting and receiving subspaces; in each subspace optimization, the physical correlation between parameters is learned through Gaussian sampling based on an adaptive covariance matrix, the global search capability is enhanced by using an acceptance criterion containing a thermodynamic term and a quantum tunneling term to escape from a local optimum, and a periodic oscillation thermal scheduling strategy is adopted to dynamically balance exploration and utilization, so that the application has the characteristics of low overhead, fast convergence and high robustness, and is suitable for 6G millimeter wave and terahertz movable array MIMO systems.

This utility model discloses a calibration device for an accelerometer, relating to the field of sensor calibration technology. It includes a base, a sensor under test, a standard sensor, and a data acquisition processor. The base is equipped with a vibration generating mechanism, which in turn has a clamping mechanism for fixing the sensor under test and the standard sensor. The vibration generating mechanism generates controllable vibration acceleration. Using a variable frequency motor, a rotating disk, a cam, and a swinging component, rotation is converted into periodic oscillation. Combined with components such as a sliding rod and a vibration table, and aided by the U-shaped frame and threaded rod of the clamping mechanism, the sensor under test and the standard sensor can be quickly fixed, enabling efficient calibration. Simultaneously, the variable frequency motor can flexibly adjust its output, and in conjunction with the cam and swinging component, it can generate various vibration accelerations, overcoming the limitations of existing devices in adjusting vibration parameters and significantly improving the accuracy of calibration results.

The present application relates to the technical field of hydrological data, and more particularly to a system and method for comprehensive analysis of hydrological element change trend. The method comprises the following steps: obtaining time series data of hydrological elements of a target basin, eliminating the influence of upstream reservoir regulation and storage in the time series data of hydrological elements, and obtaining a natural runoff sequence; performing linear trend analysis on the natural runoff sequence under different time scales to obtain a regression slope parameter; when a non-zero trend signal is detected in the regression slope parameter, triggering a non-parametric significance test to generate an effective trend signal; decomposing the natural runoff sequence into multi-level periodic characteristics by time-frequency wavelet; identifying the main oscillation period of the multi-level periodic characteristics, calibrating the dominant period and the average change period, and constructing a periodic oscillation atlas of hydrological elements. The present application integrates trend signals, periodic characteristics and persistence parameters to construct a trend comprehensive identification path, and realizes the characterization of the change characteristics of hydrological elements.

The invention relates to the technical field of laser spectrum measurement, in particular to a synchronous temperature and pressure measurement device based on a femtosecond laser-induced grating spectrum technology, which uses two beams of femtosecond laser pulses with the same pulse energy and polarization state to interfere with each other in a medium. The thermal grating is induced through rapid energy deposition, sound waves are generated on the cross section of the thermal grating, then a beam of continuous laser enters the thermal grating at a first-order Bragg diffraction angle, photon-phonon interaction is generated between the continuous laser and the sound waves, and therefore a beam of coherent scattered light is generated at a four-wave mixing phase matching angle; the femtosecond laser induces the grating to scatter the signal light. The signal light has a periodic oscillation structure in time, the signal intensity presents an exponential decay rule along with time, and the oscillation period and the decay time constant are respectively related to the sound wave propagation speed and the thermal diffusion rate, so that the dependency relationship between the measurement result and the gas state can be established; therefore, temperature and pressure information can be calculated by measuring femtosecond laser induced grating scattering signals.

This invention belongs to the field of compressor efficiency evaluation technology. It provides a compressor efficiency evaluation method and system based on predictive degradation trends. The method includes: determining whether high-frequency oscillations in the efficiency signal are caused by a rotating stall cluster through time-domain analysis of high-frequency periodic oscillations and frequency-domain analysis of characteristic peaks; if so, dividing the stall cluster oscillation characteristic frequency band and the low-frequency characteristic frequency band of efficiency degradation into two frequency bands; acquiring the compressor efficiency oscillation + degradation composite signal, performing wavelet packet decomposition according to the divided frequency bands, removing the decomposed oscillation characteristic frequency band signal, retaining only the efficiency degradation characteristic frequency band signal, and reconstructing a pure efficiency degradation trend curve without oscillation interference through spline interpolation and moving average; and performing linear / nonlinear degradation rate fitting calculation and analysis based on the pure efficiency degradation trend curve, combined with morphological analysis of the pure efficiency degradation trend curve, to determine the compressor efficiency degradation trend.

The invention discloses a fan blade pneumatic unbalance detection system and method based on laser ranging, and relates to the technical field of measurement, and the method comprises the steps: controlling laser ranging equipment to emit continuous laser beams to a fan impeller rotating plane, and collecting continuous scanning data streams; mapping the continuous scanning data stream to a polar coordinate system to generate an actually measured phase distribution diagram; generating a standard phase grid by taking the instantaneous average rotating speed of the fan impeller as a reference; performing cross-correlation alignment on the actually measured phase distribution diagram and the standard phase grid, and calculating the time phase residual error of each blade passing through the laser beam relative to the standard phase grid; extracting dynamic fluctuation characteristics of the time phase residual error in a plurality of continuous rotation periods; and when the dynamic fluctuation characteristic shows periodic oscillation locked with the rotating speed frequency and the amplitude does not attenuate along with the variable pitch action, a judgment result of pneumatic imbalance is generated. By implementing the application, the detection accuracy of the pneumatic unbalance of the wind generating set can be improved.

The application discloses a data center electromechanical system model identification method and system, and particularly relates to the technical field of data center electromechanical system operation management. The residual error between the preset model output and the actual output is subjected to nonlinear mapping to generate a compensation signal, and the fine residual error is obtained after superposition. The degradation index is extracted from the fine residual error and the compensation signal. The decoupling matrix is constructed according to the causal relationship between the degradation index and the variable, and the control instruction is decoupled. The frequency spectrum of the residual deviation after decoupling is monitored, and the damping signal is injected when periodic oscillation is detected. The model error is continuously evaluated, and the re-identification is triggered when the threshold value is exceeded and the time is continuous, the model is updated with real-time data, and iteration is performed. The application improves the model accuracy through nonlinear compensation and degradation tracking, eliminates oscillation through decoupling and damping, and realizes adaptive tracking through online model updating, thereby reducing local overheating, reducing energy consumption and equipment wear.

The invention discloses a train multi-agent tracking control method under communication limitation, and the method comprises the following steps: S1, designing a dynamic model of a train formation for a high-speed train dynamic model; s2, designing a nonsingular sliding mode surface, substituting the nonsingular sliding mode surface into the kinetic equation, and designing an equivalent control law and a total control law; s3, designing a fixed threshold strategy based on the control input signal error, and constructing an event triggering condition; s4, estimating an unmeasurable state by using a local measurable state through information interaction of adjacent vehicles, providing full state feedback for a controller, and designing a distributed observer; the method has the beneficial effects that an improved terminal sliding mode surface structure is provided by adopting a non-singular terminal sliding mode surface design, the non-singular terminal sliding mode surface design is a co-prime odd number, it is ensured that a fraction index cannot be reduced, periodic oscillation is avoided, and the problem of singularity of traditional sliding mode control in time is eliminated through a fraction index item.

The invention relates to the field of fiber bundle spreading. The crank cooperative type multi-degree-of-freedom fiber spreading equipment comprises a fixed bracket, and a first fiber spreading device, a compression roller device and a second fiber spreading device which are arranged in sequence, the first filament spreading device comprises an upper row roller set and a lower row roller set which do periodic reciprocating rectilinear motion with opposite directions and controllable strokes, and the lower row roller set does periodic reciprocating rectilinear motion and meanwhile does periodic amplitude-controllable swing in the direction perpendicular to the motion direction of the lower row roller set. The invention further relates to a working method of the crank cooperative type multi-degree-of-freedom fiber spreading equipment. The first filament spreading device provides reciprocating rectilinear motion with the phase difference of 180 degrees and compound motion of a swing stroke, a dynamic alternating tension field (stress fluctuation is controllable) is formed in a fiber bundle, and the internal stress dispersion efficiency of the fiber bundle is improved.

The invention provides a generator set active power oscillation suppression performance evaluation method and system, and the method comprises the steps: simulating the weak damping characteristics of a power grid in the control of a generator set, injecting controllable oscillation excitation, and calculating the oscillation period and damping ratio of a system in real time through a mode of performing weakening first and then performing testing, thereby achieving the quantitative evaluation of the active power oscillation suppression performance. An accurate basis is provided for optimizing unit damping parameters and improving suppression measures; the method comprises the following steps; injecting weakening logic; newly adding starting oscillation basic quantity control logic; the periodic oscillation quantity with the amplitude gradually increasing along with time is superposed in the set value of the active power PID controller under the action of weak damping, the control logic exits after the generator set is excited to oscillate, the oscillation is maintained or expanded by the generator set power generation control system, and meanwhile, a manual termination trigger mechanism and the maximum duration limit are set; establishing an oscillation period and damping ratio calculation logic; and performing suppression performance evaluation and conclusion output based on the damping ratio.

A radar signal generation device comprising: a generator (110) of periodically repeated series of trigger pulses (sPRFs) having a linearly variable time spacing; and an oscillator (120) configured to receive said trigger pulses as input and to generate a train of periodic oscillations corresponding to each said trigger pulse; characterized in that said oscillator (120) has a variable frequency depending on a control signal (Vtune); and in that the device also comprises a generator (112) of said control signal, adapted to linearly vary the frequency of the oscillator (120) from one train of periodic oscillations to another.Radar device comprising a transmit channel (1) including such a device for generating a radar signal; and a receive channel (2) configured to receive echoes of said radar signal and to demodulate them synchronously with their generation so as to extract time-of-flight information. Figure for the abbreviation: Fig. 4.

Method and circuit arrangement for determining characteristic parameters of an oscillator (OSC) comprising the steps: comparing (S1) an output signal (x) of the oscillator (OSC) with a threshold value (x thr) to determine a comparison result; generating (S2) a feedback signal (FB) which, depending on the determined comparison result, is subjected to one of two different feedback levels (ACC+; ACC-); delaying (S3) the generated feedback signal (FB) with a delay time (tD) to establish a continuous periodic oscillation of the feedback oscillator; and determining (S4) the characteristic parameters of the oscillator (OSC) based on samples within a self-oscillation period of a triggered self-oscillation of the oscillator (OSC).

This invention belongs to the field of data analysis technology, specifically relating to a method and system for diagnosing the operational status of a constant humidity system. The method includes: synchronously acquiring the humidity status of the cab and the engine speed time series; performing differential and standardization processing on the humidity data to construct three core diagnostic indicators: dynamic trajectory entropy, three-dimensional trajectory cyclicity, and resonance decoupling index. The dynamic trajectory entropy is used to initially screen for abnormal states with high uncertainty; the three-dimensional trajectory cyclicity is used to distinguish between periodic oscillations and random noise; the resonance decoupling index uses engine speed as an external reference source and, through spectrum analysis, accurately determines whether the source of periodic fluctuations is a true fault caused by internal control oscillations or a false fault caused by resonance interference from external sources such as the engine. Finally, through layer-by-layer logical judgment of these three indicators, accurate diagnosis of the constant humidity system status is achieved, effectively avoiding misjudgments.