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Measurement of liquid circulation in concentric airlift reactors by cross-correlation method

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 1997年第1期30卷 23-29页

作者： Hashiba, N Kojima, E UNIV TSUKUBA INST APPL BIOCHEMTSUKUBAIBARAKI 305JAPAN

The two-dimensional velocity and direction of liquid flow were measured in the downcomer of concentric airlift reactors by a cross-correlation method utilizing a three-electrode electrochemical probe. The process of eliminating the part of bubble signals was necessary and developed systematically. The optimum value of the distance between the microelectrodes was decided for the gas-liquid two-phase now. The circulation velocities obtained with this probe agreed with those by a solid tracer method. When the ratio of the diameter of the draft tube to that of the column was small (D-i/D-o=0.29), circumferential components of the liquid velocity as well as vertical components were detected to be significant at higher superficial gas velocities.

关键词： fluid dynamics liquid circulation airlift reactor cross-correlation method multi-electrode probe

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Simultaneous measurement of two-dimensional velocity and direction of liquid flow by cross-correlation method

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JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 1996年第4期29卷 577-581页

作者： Hashiba, N Kojima, E UNIV TSUKUBA INST APPL BIOCHEMTSUKUBAIBARAKI 305JAPAN

Liquid velocity and direction were measured by an electrochemical probe. The probe had three microelectrodes, and the two-dimensional direction and velocity were calculated from a cross-correlation function of the voltage fluctuations. Measurements were done in a rotating basin, and the most suitable values of parameters-the distance between the electrodes and the time span of calculating the cross-correlation function-were decided. This probe can be constructed cheaply, and it can be used in dilute aqueous solutions of sodium chloride (0.01 M) and also mediums for cultivation of microorganisms without employing commonly used electrolytes such as ferricyanide.

关键词： fluid dynamics liquid flow cross-correlation method multi-electrode probe electrochemical probe

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Visualization of Vibration Phenomena on Model Turbine Rotor Using cross-correlation method Based on In-Place Fast Haar Wavelet Transform

Visualization of Vibration Phenomena on Model Turbine Rotor ...

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General Meeting of the IEEE-Power-and-Energy-Society

作者： Kawada, Masatake Yamada, Koji Kaneko, Yasutomo Isaka, Katsuo Univ Tokushima Inst Sci & Technol 2-1 Minami Johsanjima Tokushima 7708506 Japan Univ Calif Los Angeles Los Angeles CA USA Nagoya Univ Elect & Mech Engn Nagoya Aichi Japan Hokkaido Univ Mech Engn Sapporo Hokkaido 060 Japan

ISBN: (纸本)9781424419050

In this paper we present the results of applying the cross-correlation (CC) method based on the in-place fast Haar wavelet transform (IpFHWT) to know the correlation between the received signals associated with vibration phenomena on a model turbine rotor. It is required to detect typical vibration of turbine and generator accurately. Modern power plants usually use one-high pressure and one or two lower pressure turbines. We make the model turbine with three rotors supported with journal bearings and simulated abnormal conditions. The vibration caused by the abnormal conditions is measured with accelerometers, displacement meters, and acoustic emission sensors. The cross-correlation of acceleration signals is obtained in the time-frequency domain by using the CC-IpFHWT.

关键词： Turbine Generator Model Turbine Rotor Vibration Diagnosis Rotor-to-Stator Contact In-Place Fast Haar Wavelet Transform cross-correlation method

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Visualization of Propagation Signals Accompanied by Contact Using cross-correlation method Based on In-Place Fast Haar Wavelet Transform

Visualization of Propagation Signals Accompanied by Contact ...

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General Meeting of the IEEE-Power-and-Energy-Society

作者： Kawada, Masatake Yamada, Koji Kaneko, Yasutomo Isaka, Katsuo Univ Tokushima Inst Technol & Sci 2-1 Minami Johsanjima Tokushima 7708506 Japan Chubu Elect Power Co Inc Elect Power R&D Ctr Nagoya Aichi 4598522 Japan Mitsubishi Heavy Ind Co Ltd Takasago Res & Dev Ctr Vibrat & Noise Control Lab Takasago Hyogo 6768686 Japan

ISBN: (纸本)9781424442409

In this paper we present the results of applying the cross-correlation (CC) method based on the in-place fast Haar wavelet transform (IpFHWT) to visualize the propagation signals associated with contact on a model turbine rotor. It is required to detect typical vibration and to localize the position of failure in turbine and generator accurately. Because modern power plants usually use one-high pressure and one or two lower pressure turbines and a generator, we use the turbine model with three rotors. The cross-correlation of acceleration signals is obtained in the time-frequency domain by using the CC-IpFHWT. From the cross-correlation the signals accompanied by the contact can be extracted.

关键词： Turbine Generator Model Turbine Rotor Vibration Diagnosis Rotor-to-Stator Contact In-Place Fast Haar Wavelet Transform cross-correlation method

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Debris flow velocity estimation: A comparison between gradient-based method and cross-correlation method

Debris flow velocity estimation: A comparison between gradie...

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Conference on Image Processing - Algorithms and Systems

作者： Uddin, MS Inaba, H Yoshida, Y Itakura, Y Kyoto Inst Technol Dept Elect & Informat Sci Sakyo Ku Kyoto 6068585 Japan

ISBN: (纸本)0819444073

Debris flow causes lot of damages all over the world. The surface velocity of such a natural random flow is one of the important physical parameters that are considered in drawing a hazard map or constructing a sediment control dam. Gradient-based method along with a multiscale smoothing operation finds application in the two-dimensional velocity estimation of a debris flow from its video images. This paper investigates the performance of another optical flow determination technique - the cross-correlation method in the above application and compares the results with those obtained by the gradient-based method. A computer simulation with synthetic random moving images shows that the accuracy of the cross correlation method is higher than that of the gradient-based method.

关键词： debris flow spatial filtering optical flow estimation gradient-based method cross-correlation method

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3-DIMENSIONAL PTV BASED ON BINARY cross-correlation method - (ALGORITHM OF PARTICLE IDENTIFICATION)

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JSME INTERNATIONAL JOURNAL SERIES B-FLUIDS AND THERMAL ENGINEERING 1993年第2期36卷 279-284页

作者： YAMAMOTO, F UEMURA, T TIAN, HZ OHMI, K OSAKA UNIV FAC ENGN SCITOYONAKAOSAKA 560JAPAN XIAN JIAOTONG UNIV XIANPEOPLES R CHINA OSAKA SANGYO UNIV FAC ENGNDAITOUOSAKA 574JAPAN

The present study proposes a new method of particle identification in three-dimensional particle-tracking velocimetry (3D PTV) using binary image data. It is based on the necessary condition for particle identification and the 3D cross-correlation method for evaluating the similarity of particle distribution patterns in two spaces. Computer simulations are carried out to investigate the effects of the sizes of particles, search subregion and identification subregion on the particle identification performance. The method has two key advantages. One is quick and accurate particle identification performance and the other is that the computer memory required for the computation of particle identification is generally small compared to other methods.

关键词： 3-DIMENSIONAL FLOW MEASUREMENT PARTICLE-TRACKING VELOCIMETRY IMAGE PROCESSING PARTICLE IDENTIFICATION cross-correlation method

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Design and Implementation of an Ultrasonic Flowmeter Based on the cross-correlation method

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SENSORS 2022年第19期22卷 7470页

作者： Ren, Rui Wang, Hongliang Sun, Xiaolei Quan, He North Univ China Natl Key Lab Elect Measurement Technol Key Lab Instrumentat Sci & Dynam Measurement Minist Educ Taiyuan 030051 Peoples R China

Ultrasonic flowmeters play an important role in industrial production, aerospace and other fields. In this paper, a high-precision ultrasonic flowmeter based on the cross-correlation method is designed, and the commercial finite element software COMSOL Multiphysics 5.6 is used to simulate the propagation process of ultrasonic waves during flow measurement, and the implementation process of the cross-correlation algorithm is simulated by Python language. The flowmeter adopts the cross-correlation algorithm to improve the measurement accuracy of ultrasonic time of flight and adopts the method of combining FPGA and an embedded microprocessor to improve operation efficiency. In order to verify the performance of the flowmeter, we tested the flowmeter on the National Institute of Metrology and the self-built test platform, using the still water dragging method, the dynamic volume method and the field comparison method, respectively. The results show that the flowmeter has the ability to test the flow under the condition of high flow velocity (26 m/s) and a pipe diameter in the range of DN6 similar to DN1600, that the absolute value of the relative indication error does not exceed 0.815% and that the repeatability does not exceed 0.150%. The designed ultrasonic flowmeter has high measurement accuracy, good repeatability, strong stability and a wide application range.

关键词： ultrasonic flowmeter cross-correlation method finite element simulation ultrasonic time of flight

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The cross correlation method response prior to earthquakes using foF2 data from various ionospheric stations

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ADVANCES IN SPACE RESEARCH 2019年第8期63卷 2638-2658页

作者： Benghanem, K. Kahlouche, S. Abtout, A. Beldjoudi, H. CRAAG Bouzareah Alger Algeria Ctr Tech Spatiales CTS ASAL Agence Spatiale Algerienne Arzew Oran Algeria

Considering the non-systematic aspect in detection of seismo-ionospheric precursors;we propose an attempt to characterize the nature of the perturbations in the F2 ionospheric layer prior to earthquakes using cross-correlation method. The effectiveness of cross-correlation method is not questioned;but could the use of more than two observation points undergoing identical influence of solar activity reveal the same perturbations for the same earthquake? The cross-correlation method is known for its ability to eliminate the solar activity effect when two measurements of the critical frequency of the F2 ionospheric layer (foF2) are correlated. As the observation points (ionosonde stations) used have similarity of geographical location they necessarily undergo the same influence of solar activity. Thus only the seismogenic aspect would remain in the cross-correlation coefficients. Therefore we have considered only earthquakes where there are several ionosonde stations satisfying the conditions of use of cross-correlation method. Using several stations should allow determine whether the cross-correlation coefficients vary in the same way for the same event or not. More than Fifty earthquakes from Mediterranean Basin and Japan with magnitude 5 <= M <= 6.6 and depth not exceeding 40 km are selected according to the availability of critical frequency data of the F2 ionospheric layer. Results vary from one earthquake to another. This is normal because each earthquake has its own characteristics. But the response of the cross-correlation technique is not always the same for the same event. Thus, there are cases where, for the same event, the variation of cross-correlation coefficients has the same behavior for the various pairs of stations considered and other cases where the response is not similar. Neither the magnitude of the earthquake nor the position of the internal station with respect to the epicenter, nor the position of the external stations relative to the internal

关键词： Ionosphere foF2 Earthquake cross-correlation method Seismo-ionospheric precursors

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Visualization of Vibration Phenomena on Model Turbine Rotor Using cross-correlation method Based on In-Place Fast Haar Wavelet Transform

Visualization of Vibration Phenomena on Model Turbine Rotor ...

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IEEE Power and Energy Society General Meeting

作者： Masatake Kawada Koji Yamada Yasutomo Kaneko Katsuo Isaka The Institute of Technology and Science The University of Tokushima 2-1 Minami-Johsanjima Tokushima 770-8506 Japan

ISBN: (纸本)9781424419050

关键词： Turbine Generator Model Turbine Rotor Vibration Diagnosis Rotor-to-Stator Contact In-Place Fast Haar Wavelet Transform cross-correlation method turbines correlation methods Generator dynamos Vibration cross correlation Visualization wavelet transforms received signal SLIDE BEARING

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Computation of multi-rotor vibration phase under a single key phase measurement condition and its application in aero-engine

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2025年 230卷

作者： Hu, Minghui Han, Baole Ge, Xiangdong Jin, Yaqiang Wang, Weimin Jiang, Zhinong Beijing Univ Chem Technol State Key Lab High End Compressor & Syst Technol Beijing 100029 Peoples R China Beijing Univ Chem Technol Beijing Key Lab Hlth Monitoring & Selfrecovery Hig Beijing 100029 Peoples R China Aero Engine Corp China Shenyang Aeroengine Inst Shenyang 110042 Peoples R China Qingdao Mingserve Technol Ltd Qingdao 266000 Peoples R China Beijing Univ Chem Technol Key Lab Engine Hlth Monitoring Control & Networkin Minist Educ Beijing 100029 Peoples R China

The vibration phase is essential for fault diagnosis (e.g., rotor unbalance, rotor misalignment) and dynamic balancing. Accurate phase calculation relies on obtaining the key phase pulse signal associated with each rotor's key phase reference point, capturing the phase zero point once per revolution. In complex gear systems, only some rotors' key phase signals are measurable, which complicates the calculation of other rotors' vibration phases. To address this challenge, we propose a method for calculating the multi-rotor vibration phase under a single key phase measurement condition. First, a phase zero point synchronization marking method is introduced to identify each rotor's physical phase reference point. Then, a phase compensation calculation method based on the target rotor's rotation angle is developed under a single key phase measurement condition. This method accounts for computer rounding errors when calculating the target rotor's rotation angle. Finally, using the collected vibration data, key phase signal, and calculated phase compensation values, the cross-correlation method determines the target rotor's vibration phase. Experimental results from the gear system test rig and aero-engine equipment validate the effectiveness of the proposed method, demonstrating that the vibration phase of multiple rotors can be accurately calculated with an error of less than 5 degrees.

关键词： Aero-engine Rotor unbalance Phase extraction Phase compensation cross-correlation method

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