12 results about "Periodic oscillation" patented technology

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 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 discloses a nano-film thickness measurement method based on terahertz sub-wavelength interference enhancement. The method comprises the following steps: S1, acquiring a terahertz time domain signal of a to-be-measured sample formed by a film / substrate in a reflection or transmission mode; s2, performing frequency domain transformation on the time domain signal to obtain an amplitude spectrum of the time domain signal; s3, extracting a characteristic frequency interval of a periodic oscillation signal generated by multi-beam interference in the thin film; and S4, based on the characteristic frequency interval and the refractive index n of the thin film material, calculating to obtain the physical thickness d of the thin film. According to the nano-film thickness measurement method based on terahertz sub-wavelength interference enhancement, the multi-beam interference effect generated by terahertz waves reflected or transmitted by the upper interface and the lower interface of an ultrathin film is utilized, tiny thickness information is converted into periodic interference fringes easy to observe in the frequency domain, and accurate inversion of the sub-wavelength thickness is achieved.

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).

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 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 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.

This invention discloses a method for controlling the periodic oscillation of billets on the tapping roller conveyor of a special steel heating furnace. Specifically, it relates to the field of special steel processing technology and proposes a "dynamic heat load balancing" mechanism. This mechanism utilizes the periodic forward and reverse oscillation of the billet on the roller conveyor, with an oscillation amplitude of 500–1000 mm and a frequency of 0.1–0.5 Hz. This causes the contact point between the high-temperature billet and the roller conveyor to change over time, avoiding local temperature exceeding limits. Actual measurements show that the surface temperature difference of the roller conveyor is reduced by more than 60%. This method breaks through the traditional "static / unidirectional movement" thinking and transforms the 80-second waiting time into a controllable oscillation cycle. The solution can be extended to fields such as hot delivery of continuously cast billets and non-ferrous metal heating furnaces. A Modbus interface has been reserved to support multi-furnace collaboration. The oscillation process utilizes residual heat to reduce cooling water consumption, resulting in a 5% energy saving per tapping.

The invention belongs to the technical field of semiconductor manufacturing, and particularly relates to a temperature oscillation growth method for improving the uniformity of a GaAs epitaxial layer, which comprises the following steps of: placing a GaAs substrate in an MOCVD (Metal Organic Chemical Vapor Deposition) reaction chamber to carry out hydrogen atmosphere thermal cleaning; setting process parameters such as target growth temperature, gas flow and reaction chamber pressure; setting the amplitude and period of periodic oscillation around the target growth temperature; iII-group and V-group source gases are synchronously introduced, and a temperature oscillation program is started, so that the temperature of the substrate is periodically oscillated according to set parameters, and epitaxial growth is carried out; continuously oscillating and growing to a target thickness; and stopping the III-group source, and cooling under the protection of the V-group source. The growth interface is actively disturbed through temperature oscillation, so that the growth tends to a two-dimensional layered mode, and the macroscopic thickness and component uniformity of the epitaxial layer are improved. Periodic temperature change is equivalent to in-situ annealing, dislocation density is reduced, and crystal quality is improved. And the method has universality on epitaxial growth of various III-V group compounds such as GaAs, AlGaAs, InGaAs and the like.

Faults in a periodically oscillating MEMS mass are detected by processing a position signal, having an amplitude and oscillation frequency, generated as a function of mass position. First and second reference signals formed by samples of quadrature sinusoids at the oscillation frequency are generated. First and second multipliers generate a first product signal and a second product signal, respectively, via multiplication of the position signal by the first and second reference signals. The first and second product signals are low pass filtered to generate first and second filtered signals, respectively. An estimator circuit determines estimates of the amplitude as a function of the first and second filtered signals. A decision circuit detects the presence of faults on the basis of a comparison of the estimates with a range of values.