Papers by Keyword: Spectrum Analysis

Abstract: A reduced-scale model of 7-story reinforced concrete shear wall structure is made. Shaking-table test of the model is carried out. Two test conditions are considered. In the first condition, fixed base is used. In another condition, soil structure interaction is considered. According to the experimental results, the dynamic characteristic and seismic performance of shear wall structure is studied. The acceleration time history response of model structure is obtained. Based on the time-history response, the dynamic characteristics of model structure are studied by spectrum analysis. The Finite Element Model of actural structure is established by ANSYS. The dynamic characteristics and seismic performance of actural structure are studied. By comparing the experiment results and numerical analysis results under the fixed-base condition, the rationality of the ANSYS model and numerical analysis method of are verified.

Abstract: In order to solve the vibration problems of car high-pressure cylindrical cylinders, Plate and Shell Vibration Theory is used for the calculation and analysis of the vibration characteristics. The vibration frequencies and modes of such cylinders are obtained. At the same time, the corresponding results are gotten through ANSYS12.0 simulation calculation. The similarities and differences of the both vibration frequencies and the changes of the respective modes are compared and analyzed to support the farther safety performance analysis of such cylinders in the vibration environment.

Abstract: The test was simulated for the thin-walled cylinder structure of aeroengine stator casing. Based on the software of LMS-TEST, the experiment of the structure with bolted flange joints was successfully completed for the vibration test analysis and the paper completed the testing under different pre-tightening force. Through the analysis of the measured data, the corresponding spectrum and difference value curve were obtained, the research results showed that the nonlinear characteristics of the bolted flange joint was significant influence on the dynamic responses of the structure, the various nonlinear vibration phenomenon and the signal asymmetry were obvious under different pre-tightening force, which was closely related to the state of the bolted pre-tightening force. By the information of the spectrum and acceleration difference curve, the extent of the bolt tightness can be determined, which can provide relevant reference information for the diagnosis of bolted joint status in the aeroengine stator casing.

Abstract: The noise SPL and spectrum characteristics were tested and analyzed for the Shenzhen metro platform when the metro is inbound and outbound by using the noise and vibration measurement and analysis system. Time-domain SPL distribution diagrams shows, causing the largest noise level inside platform is mainly from the station radio, when no station radio, metro wheel-rail noise and air-conditioning fan noise have become a major SPL source in platform. The noise level at the platform is between 73dB-76dB. Frequency domain noise spectrum diagram shows, the noise SPL peak appeared in both low frequency and mid frequency ranges. Low frequency noise peak appears at 125Hz and 250Hz frequency band, mainly from the site of passengers talking and footsteps. Mid frequency noise peak is located in the 500Hz-1000Hz range, mainly from station radio, metro wheel-rail noise and air-conditioning fan and so on. This study provides a reference for noise reduction design of the metro platform.

Abstract: This article is about detecting and analyzing the motor noise vibration signal with virtual instrument technology based on the LabVIEW basic platform, realizing the recognizing and processing of the motor noise source, and providing effective parameters for the motor fault diagnosing.

Abstract: NIR spectrum is established as an independent analysis technology and applied in more fields. The demand of portable and fast analysis is impeding. Using JDSU’s MicroNIR1700 NIR spectrum engine as the hardware platform, we contrived the NIR spectrum acquisition and analysis system. The spectrum data is output from the engine through USB port. We develop the software on computer by C# language. The software has the function of spectrum acquisition, pretreatment, modeling and prediction, the result is displayed by graphs and tables. This system is tested successfully by using flour sample which lays the foundation for promoting the portable NIR acquisition and analysis system.

Abstract: The noise of different points in four sections of Shenzhen subway was tested by this paper. Real-time SPL and noise spectrum distribution curves at bogie were given, while the equivalent SPL curve was also shown. The relationship of subway speed and noise SPL was investigated. The regular of noise spectrum characteristics and SPL was obtained. The results show that the noise SPL increases with the increase of the speed. Looking from the frequency range, the frequency corresponding to larger noise SPL amplitude mainly concentrates in the lower frequency while the subway stopping, the frequency corresponding to larger noise SPL amplitude mainly concentrates in high frequency while the subway running.

Abstract: In this paper, frequency spectrum of infrasound signal collected was analyzed based on MATLAB. The infrasound power level of change with frequency distribution and the infrasound harmonic of each frequency component of the sound pressure amplitude can be made up judgment visually by frequency spectrum analysis and amplitude spectrum analysis, and thus we can obtain different conditions of infrasound properties scientifically and quantitatively.

Abstract: In the field of machinery manufacture, broken state at the time of the cutting tool in cutting metal, recognition has always been a study is of great significance. Currently, for the state of tool wear and collapse edge damage identification method already has a mature experience. However the existing condition monitoring methods are often used in accuracy and convenience has limitations, this paper USES the acoustic emission technology, as a kind of integrated online test sys tem design lay the foundation. This paper aimed at the sensor in the wireless transmission module, the performance characteristics of tool condition monitoring system of the main structure was designed, and then by acoustic emission signal from the cutting tool in cutting process as the research object, studies the cutting tool characteristics of acoustic emission signal under different damage state, for the on-line monitoring system design and calibration to provide theoretical support.

Abstract: In the face of the carrier signal is discrete spectrum analysis, frequency, amplitude and phase are likely to produce the error problem. Based on discrete spectrum correction theory, derivation of the carrier signal causes the error when the discrete spectrum analysis and using the generalized cosine window for the error of the discrete spectrum analysis.