scholarly journals In Situ Measurement of Wind-Induced Pulse Response of Sound Barrier Based on High-Speed Imaging Technology

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Chunli Zhu ◽  
Jie Guo ◽  
Dashan Zhang ◽  
Yuan Shen ◽  
Dongcai Liu
Keyword(s):  
High Speed ◽  
Vibration Response ◽  
Wind Pressure ◽  
Vibration Measurement ◽  
Head Wave ◽  
High Speed Imaging ◽  
Imaging Technology ◽  
Whole Process ◽  
Sound Barrier ◽  
Extraction Algorithm

The lifetime of the sound barrier is threatened by high-speed train-induced impulsive wind pressure as it passes by. The vibration response of the sound barrier during the process of train passing is difficult to be measured using conventional measurement methods because of the inconvenience of the installation of markers on the sound barrier. In this paper, the high-speed camera is used to record the whole process of the train passing by the sound barrier. Then, a displacement extraction algorithm based on the theory of Taylor expansion is proposed to obtain the vibration response curve. Compared with the result simulated by using the finite element method, the video extraction result shows the same head wave and tail wave phenomenon, demonstrating that the vibration measurement by using the high-speed imaging technology is an effective measuring way. It can achieve noncontact and remote vibration measurement and has important practical value.

Design of Air-Lock Valve of the Mesh Roller-Type Unginned Cotton and Film Remnant Separator

2013 ◽  
Vol 278-280 ◽  
pp. 121-127
Author(s):  
Hong Lei An ◽  
Ruo Yu Zhang ◽  
Za Kan ◽  
Xiao Liang Li ◽  
Ying Lan Jiang
Keyword(s):  
Friction Coefficient ◽  
Flow Condition ◽  
High Speed ◽  
High Speed Imaging ◽  
Imaging Technology ◽  
Validation Test

Air-lock valve is an important part of the mesh roller-type unginned cotton and film remnant separator. To improve the structure of the air-lock valve, the cotton flow condition in the separator was analyzed by using high speed imaging technology firstly. Then friction coefficient between unginned cotton and mesh roller was tested by experiment. Meanwhile, some parameters of the air-lock valve were obtained by analyzing different phenomenons that are blockings in the air-lock valve during running of the separator. Finally, the validation test was done, the results indicate that the improved air-lock valve is more reasonable than before, and the blocking can be avoided successfully.

scholarly journals Wind Load Characteristics of Wind Barriers Induced by High-Speed Trains Based on Field Measurements

2019 ◽  
Vol 9 (22) ◽  
pp. 4865 ◽  
Author(s):  
Zou ◽  
Fu ◽  
He ◽  
Cai ◽  
Zhou ◽  
...  
Keyword(s):  
High Speed ◽  
Field Measurements ◽  
Wind Pressure ◽  
Wind Loads ◽  
Head Wave ◽  
Pulse Excitation ◽  
Multi Resolution Analysis ◽  
High Speed Trains ◽  
Resolution Analysis ◽  
Wind Barrier

This paper focuses on field measurements and analyses of train-generated wind loads on wind barriers (3.0 m height and porosity 0%) with respect to different running speeds of the CRH380A EMU vehicle. Multi-resolution analysis was conducted to identify the pressure distribution in different frequency bands. Results showed that the wind pressure on the wind barrier caused by train-induced wind had two significant impacts with opposite directions, which were the “head wave” and “tail wave”. The peak wind pressure on the wind barrier was approximately proportional to the square of the speed of the train, and the peak wind pressure decreased rapidly along the wind barrier height from the bottom of the wind barrier. The maximum wind pressure occurred at the rail surface height. Furthermore, results of the multi-resolution analysis illustrated that the energy of the frequency band from 0 to 2.44 Hz accounted for 94% of the total energy. This indicated that the low-frequency range component of the wind pressure dominated the design of the wind barrier. The frequency of pulse excitation of train-induced wind loads may overlap with the natural frequency of barriers, and may lead to fatigue failure due to cyclic loads generated by the repeated passage of high-speed trains. In addition, the speed of the train had a negligible effect on the energy distribution of the wind pressure in the frequency domain, while the extreme pressure increased slightly with the increase of the speed of the train.

scholarly journals Vision-Based Faint Vibration Extraction Using Singular Value Decomposition

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Xiujun Lei ◽  
Jie Guo ◽  
Chang’an Zhu
Keyword(s):  
Singular Value Decomposition ◽  
High Speed ◽  
Singular Value ◽  
Vibration Measurement ◽  
Displacement Sensor ◽  
Remote Measurement ◽  
Engineering Structures ◽  
High Speed Rail ◽  
Sound Barrier ◽  
Value Decomposition

Vibration measurement is important for understanding the behavior of engineering structures. Unlike conventional contact-type measurements, vision-based methodologies have attracted a great deal of attention because of the advantages of remote measurement, nonintrusive characteristic, and no mass introduction. It is a new type of displacement sensor which is convenient and reliable. This study introduces the singular value decomposition (SVD) methods for video image processing and presents a vibration-extracted algorithm. The algorithms can successfully realize noncontact displacement measurements without undesirable influence to the structure behavior. SVD-based algorithm decomposes a matrix combined with the former frames to obtain a set of orthonormal image bases while the projections of all video frames on the basis describe the vibration information. By means of simulation, the parameters selection of SVD-based algorithm is discussed in detail. To validate the algorithm performance in practice, sinusoidal motion tests are performed. Results indicate that the proposed technique can provide fairly accurate displacement measurement. Moreover, a sound barrier experiment showing how the high-speed rail trains affect the sound barrier nearby is carried out. It is for the first time to be realized at home and abroad due to the challenge of measuring environment.

A Novel Measurement Method for Muzzle Vibration Responses Based on Image Technology

2014 ◽  
Vol 1006-1007 ◽  
pp. 888-891
Author(s):  
Guang Sheng Liu ◽  
Ben Jun Zhang ◽  
Meng Yang
Keyword(s):  
Wavelet Transform ◽  
High Speed ◽  
Measurement Method ◽  
Practical Significance ◽  
High Speed Imaging ◽  
Transform Method ◽  
Imaging Technology ◽  
Vibration Responses ◽  
Image Pretreatment ◽  
Gun Firing

The measurement of muzzle vibration responses during gun firing is one of the most important factors for successful design of gun. The use and result are limited by traditional method for the effect of firing environment, so new measurement method is required, the high-speed imaging technology is one choice. The application of high-speed imaging technology in measurement of muzzle vibration is focused on qualitative analysis, in order to discuss the quantitative analysis in this paper, images of muzzle vibration responses are obtained by using high-speed vidicon. Image pretreatment is done for post processing expediently, the process of pretreatment include de-noising by using wavelet transform method, gray processing by using averaged-value method and contrast improvement by using wavelet transform method. After image pretreatment, orientation and matching is done by using correlative matching method, and then the numerical of muzzle vibration responses during gun firing are obtained. So a novel method is afforded for measuring of muzzle vibration responses during gun firing, and the new method has practical significance in the gun’s design, research and production.

Characterization of a velocity-tunable 87 Rb cold atomic source with a high-speed imaging technology

2009 ◽  
Vol 18 (8) ◽  
pp. 3373-3378 ◽  
Author(s):  
Feng Yan-Ying ◽  
Zhu Chang-Xing ◽  
Wang Xiao-Jia ◽  
Xue Hong-Bo ◽  
Ye Xiong-Ying ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Imaging ◽  
Imaging Technology ◽  
Atomic Source
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