An inductive debris sensor can monitor a mechanical system's debris in real time. The measuring accuracy is significantly affected by the signal aliasing issue happening in the monitoring process. In this study, a...
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An inductive debris sensor can monitor a mechanical system's debris in real time. The measuring accuracy is significantly affected by the signal aliasing issue happening in the monitoring process. In this study, a mathematical model was built to explain two debris particles' aliasing behavior. Then, a cross-correlation-based method was proposed to deal with this aliasing. Afterwards, taking advantage of the processed signal along with the original signal, an optimization strategy was proposed to make the evaluation of the aliasing debris more accurate than that merely using initial signals. Compared to other methods, the proposed method has fewer limitations in practical applications. The simulation and experimental results also verified the advantage of the proposed method.
With the development of the information age, the transmission rate and transmission capacity of information continue to increase. As a wireless communication method to achieve high bit rate communication, space laser ...
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ISBN:
(数字)9781510649965
ISBN:
(纸本)9781510649965;9781510649958
With the development of the information age, the transmission rate and transmission capacity of information continue to increase. As a wireless communication method to achieve high bit rate communication, space laser communication plays an increasingly obvious role in global communications. In the current space laser communication system, the optical communication terminal uses a detector to detect the position of the received optical signal, and then the servo mechanism on it performs facula tracking. However, when a four-quadrant detector (4QD) is used to detect optical signal, the received optical signal generally contains three main types of noise, which are background radiation noise, shot noise and thermal noise. These three kinds of noise can be equivalent to Gaussian white noise. In this paper, a single-frequency cosine signal is used to modulate the intensity of the optical signal received by the 4QD, and then the modulated optical signal is detected by a spectrum analysis method based on the cross-correlation algorithm. This method reduces the relative error of the spectral line amplitude when the SNR is -5dB from 2.23% to 0.88%, and reduces the relative error of the spectral line amplitude when the SNR is -20dB from 17.6% to 5.49%. Therefore, this method can well suppress Gaussian white noise and improve the detection accuracy of modulated optical signal under extremely low SNR conditions.
This study proposes a valley-positioning-assisted discrete cross-correlation algorithm for the fast cavity length interrogation of fiber-optic Fabry-Perot (FP) sensors. Because the number of template cavity lengths th...
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This study proposes a valley-positioning-assisted discrete cross-correlation algorithm for the fast cavity length interrogation of fiber-optic Fabry-Perot (FP) sensors. Because the number of template cavity lengths that require to be cross-correlated with the spectral function of the FP sensor is dramatically decreased by considering the interference order and discretization of the template function, the computation amount can be effectively reduced without sacrificing the interrogating resolution. The feasibility and performance of the proposed algorithm were successfully verified through simulations and experiments. In the cavity length range of 20-130 mu m, fiber-optic FP sensors were successfully interrogated with high performance. The maximum error is 3.97 nm, and the resolution reaches a value of 2.62 nm.
Owing to the transverse wind, a laser beam drifts when transmitting in an atmospheric channel. The moving speed of the light spot image at the receiving end was deduced using cross-correlation algorithm. By establishi...
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Owing to the transverse wind, a laser beam drifts when transmitting in an atmospheric channel. The moving speed of the light spot image at the receiving end was deduced using cross-correlation algorithm. By establishing experiments with communication distances of 1.3 km and 100 km, the relationship between the transverse wind and the moving speed of the spot particle image on the optical transmission path was obtained. The results show that the correlation coefficients between the transverse wind and spot particle image moving speed are 0.92 and 0.83, respectively, which proves the feasibility of using the cross-correlation algorithm to obtain the transverse wind speed in atmospheric turbulence. And from this approach, the transverse wind speed and the wind vector moving image on the transmission path can be analyzed easily. (C) 2022 Society of Photo-Optical Instrumentation Engineers (SPIE)
The threshold value comparative method is generally used in the measurement of delay time in the ultrasonic pulse echo method. The measurement error is large since the threshold method is easy to turn error with the i...
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The threshold value comparative method is generally used in the measurement of delay time in the ultrasonic pulse echo method. The measurement error is large since the threshold method is easy to turn error with the interference. So in this paper, cross-correlation algorithm is used to calculate the delay time. The overlap retaining method and improved real sequence fast Fourier transform algorithm are used to calculate the cross-correlation of the transmitted sequence and received sequence, so the calculated amount and measurement error are reduced, and the accuracy of the ultrasonic level meter is improved.
At present, the co-phasing detection algorithms for segmented mirrors struggle to balance the measurement range and accuracy. This paper proposes a coarse co-phasing measurement method using the incoherent properties ...
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At present, the co-phasing detection algorithms for segmented mirrors struggle to balance the measurement range and accuracy. This paper proposes a coarse co-phasing measurement method using the incoherent properties of a broadband (400-800 nm) light source combined with the incoherence of two semicircular diffraction patterns of visible light as a template to detect the piston error, and a narrowband algorithm for fine co-phasing measurement. The diversity factors between template patterns and actual diffraction patterns can be calculated by the cross-correlation algorithm. This proposed method addresses long measurement time caused by low target flow rate and is characterized by wide measurement range, high precision and high energy utilization. The method is theoretically researched and simulated and an experimental system which was constructed to verify the effectiveness of this method achieves 15 nm detection accuracy, and the measurement range using the proposed method can match the measurement range of the actuator.
The popular geological anomaly (such as fault, river course, cave, and crack) identification methods, such as coherence cube, semblance, likelihood, and others, usually can achieve higher precision geological anomaly ...
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The popular geological anomaly (such as fault, river course, cave, and crack) identification methods, such as coherence cube, semblance, likelihood, and others, usually can achieve higher precision geological anomaly identification results when applied to the target horizon flattened seismic data, comparing to their counterparts using the target horizon-unflattened seismic data. However, these methods still face great challenges in achieving high-precision geological anomaly identification results, due to the complexity of the geological structure (or the seismic data) and the horizon tracking accuracy of the target horizon. To minimize the impact of the complexity of geological structure and the horizon tracking accuracy of the target horizon in geological anomaly identification, thereby obtaining high-precision geological anomaly identification results and providing precise labels for deep-learning-based geological anomaly identification methods, we propose a seismic facies-guided high-precision geological anomaly identification method (FHGI), basing on the concept of seismic facies and the cross-correlation algorithm. FHGI contains the flowchart of FHGI, and the seismic facies-guided trace-by-trace high-precision geological anomaly identification factor calculation (FTGC);in which FTGC consists of the target horizon-based seismic data flattening (THF), the seismic facies-guided target trace 2-D subseismic dataset generation (FTG), the cross-correlation algorithm-based target horizon further flattening (CFA), and the cross-correlation coefficient-based high-precision geological anomaly identification factor calculation (CGC). The THF aims to reduce the impact of the complexity of the geological structure and provide the input 3-D seismic data for the FTG. FTG aims to automatically generate the 2-D subseismic dataset corresponding to the target trace, thereby further reducing the impact of the complexity of the geological structure and providing the input 2-D subse
Slug flow is commonly encountered in industrial flows, its characteristics like strong intermittence and high pressure drop are usually harmful to the industrial process and facilities. Slug flow has more characterist...
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In this paper,a cost-effective and miniaturized instrument is proposed,which is based on a tunable modulated grating Y-branch(MG-Y)laser for rapid temperature measurement using a Fabry-Perot interferometer(FPI)*** FPI...
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In this paper,a cost-effective and miniaturized instrument is proposed,which is based on a tunable modulated grating Y-branch(MG-Y)laser for rapid temperature measurement using a Fabry-Perot interferometer(FPI)*** FPI sensor with a 1463-μm cavity length is a short segment of a capillary tube sandwiched by two sections of single-mode fibers(SMFs).This system has a broad tunable range(1527 nm-1567 nm)with a wavelength interval of 8 pm and a tuning rate of 100 *** sensing experiments are carried out to investigate the performance of the system by demodulating the absolute cavity length of the FPI sensor using a cross-correlation *** results show that the sensor can reach the response time as short as 94 ms with the sensitivity of 802 pm/*** from the homemade and integrated essential electrical circuits,the entire system has the small size,low cost,and practical application potential to be used in the harsh environment for rapid temperature measurement.
High precision time interval measurement between two 1PPS signals is important in timekeeping. In time interval measurement between two 1PPS, the method of using the surface acoustic wave filter (SWAF) as the time-int...
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