Papers by Keyword: Signal

Abstract: Wavelet Transform (WT) and Wavelet Packet Transform (WPT) approaches have shown great promise in the field of signal analysis in recent decades. The main merit of these methods is their capability in localization of each signal in distinct time or space interval. However, the frequency resolution of such transformation is relatively poor in high frequency regions. The WPT, which is an extended form of the WT, provides a complete level-by-level signal decomposition. Therefore, a frequency analysis creates an arbitrary time. In this study, dynamic transient analysis is performed employing a finite element software (ANSYS) on a beam and acceleration time history of various points is investigated. Then, the captured signals are decomposed to the wavelet packet components using MATLAB and energy rate index is calculated for each component utilizing a wavelet packet rate index (WPERI). The results indicate that not only are the obtained index values sensitive, but they also are precise for the crack identification.

Abstract: An improved rain detection system has been developed using a marine radar. The rain detection system is composed of a Furuno 1932 Mark II marine radar (radar scanner and display units), a radar control circuit, a signal conditioning circuit, an analog to digital converter (ADC), and a computer with a graphical user interface (GUI). The combination of the microcontroller and optocoupler in the radar control circuit was able to replace the omnipad and pushbutton control and it was also employed to activate the radar and the sector blanket mode. The signal conditioning circuit along with the ADC and the clutter removal made the video and navigation signals from the display unit become ADC-counted rain data. By comparing the ADC-counted rain data of the Furuno marine radar with the reflectivity obtained by GMR X Band weather radar, it was found that the Furuno rain detection sensitivity only spans from 30-55 dBZ.

Abstract: Optical plethysmography technology has been used to design and develop a portable device for heart rate sensor. These device, consisting of near-infrared light-emitting diodes (LEDs) and photodetectors, offer a simple means of extraction the heart rate noninvasively on fingertip’s healthy volunteers. The acquisition signal is carried out based on the detection of the absorbance of near-infrared light in blood vessels due to heart’s pump activity. The microcontroller is used as the main component of electronics module. The communication to personal computer (PC) and power supply of device are provided by USB system. The algorithm of Fast Fourier Transform (FFT) in the software was used to generate the spectra of the signal and determine the HR of the obtained signal. The performance of developed device is tested on 10 fingertips of healthy volunteers, aged 19 to 57 years. A Pulse Oximeter commercial was used as gold standard instrument for comparison of results obtained by the designed device. In this paper the correlation analysis was applied to validate the results of both devices. The analysis show that the HR measured is positively correlated. These results show that the correlation between the HR measured by both the designed PPG device and Pulse Oximeter commercial are almost perfectly linear. Thus, the pulse signals gathered by the designed device are accurately believed to be representative of the heart activity of healthy volunteers. The validation method supports that designed device can potentially be developed as a simple, low power, and portable device for the importance of biomedical research (mainly for processing biomedical signal) and clinical practices.

Abstract: The rapid development of wind power generator, the service life and efficiency but various fault often will not only shorten the wind generator, also brought the loss of life and property to the people. For fault diagnosis is an effective method of fault diagnosis using the motor vibration signals, This paper adopts the HHT analysis method, the vibration signal of the wind machine for processing fault characteristics are obtained, and the fault diagnosis,improve the efficiency of fault diagnosis, the conclusion shows that it is an effective method of fault diagnosis for fan, troubleshooting and repair of fans have important practical significance.

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: During maintaining the breakdown of the Trace Hotbox Detection System and the Automatic Train Identification System,to solve the problem of whether good or not depending on a train passing, a multi-purpose singal producer which simulates a train passing is developed.It can produce many kinds of trigger singals and fit the velocity conditions.

Abstract: As a famous one-unit algorithm, FastICA can extract source signals one by one. In many applications, someone is only interested in a specific source signal. Through incorporating reference about the desired signal into a negentropy based contrast function, a constrained optimization problem is formed. Then an improved method is proposed which can extract the desired source signal exclusively. Computer simulations demonstrate its good performance.

Abstract: Blind source extraction (BSE) is a promising technique to solve signal mixture problems while only one or a few source signals are desired. In biomedical applications, one often knows certain prior information about a desired source signal in advance. In this paper, we explore specific prior information as a constrained condition so as to develop a flexible BSE algorithm. One can extract a desired source signal while its normalized kurtosis range is known in advance. Computer simulations on biomedical signals confirm the validity of the proposed algorithm.

Abstract: The regular TV signal is converted to a Laser TV signal, the displayed video after conversion is not perfect and jitters in serious condition. The converted image is not clear, and there also exists chromatic aberration. According to gamut mapping matrix, this paper presents a dynamic real-time signal processing filter, which eliminates the noise generated in the color gamut mapping. It can effectively handle signals mapped to reduce errors and eliminate noise. We verified the feasibility of this design on a development board of Virtex-5 FPGA chip as the core ML50x.

Abstract: The signal obtained through measurement is inevitably with noise and interference. Traditional signal denoising method often takes the threshold way to process the wavelets or wavelet packets of noise signal for the purpose of denoising. Denoising by making use of slip threshold value of wavelet packets is proposed by this paper, to quantize the slip threshold value of wavelet packet decomposition coefficient, so as to obtain the reconstructed signal denoising. It is shown by the computer simulation results that the slip threshold value is with good practical value.