A Novel Approach Using Time–Frequency Analysis of Pulse-Oximeter Data to Detect Progressive Hypovolemia in Spontaneously Breathing Healthy Subjects

2011 ◽  
Vol 58 (8) ◽  
pp. 2272-2279 ◽  
Author(s):  
Nandakumar Selvaraj ◽  
Kirk H. Shelley ◽  
David G. Silverman ◽  
Nina Stachenfeld ◽  
Nicholas Galante ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Pulse Oximeter ◽  
Healthy Subjects ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Novel Approach ◽  
Spontaneously Breathing

Crack Identification by Jointly Time-Frequency Analysis

2006 ◽  
Vol 324-325 ◽  
pp. 161-164
Author(s):  
Xin Feng ◽  
Jing Zhou
Keyword(s):  
Frequency Analysis ◽  
Crack Opening ◽  
Sampling Frequency ◽  
Dynamic Responses ◽  
Crack Identification ◽  
Crack Model ◽  
Breathing Crack ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Novel Approach

A novel approach for crack identification based on jointly time-frequency analysis is presented in the paper. A bilinear stiffness model for the breathing crack was introduced to represent the nonlinear dynamics of a cracked beam. The nonlinearity of the dynamic responses due to the crack opening-closing is used to identify the occurrence of the crack. The Wigner-Wille distribution technique is applied to analyze the response signals and the instantaneous frequency is extracted as damage-sensitive feature. The numerical simulations of a breathing crack model were carried out to validate the possibility and effectiveness of the proposed approach. The effects of crack severity and sampling frequency on crack identification were also studied in the simulations respectively. The results show that the proposed method can effectively identify the crack with slight severity without any baseline model or data, and the better the identification obtains as the larger the sampling frequency. The study demonstrates that the proposed approach by using of jointly time-frequency analysis is a promising technique for crack identification.

scholarly journals Time–Frequency Analysis of Diesel Engine Noise Using Biodiesel Fuel Blends

2021 ◽  
Vol 13 (6) ◽  
pp. 3489
Author(s):  
Nemat Keramat Siavash ◽  
Golamhassan Najafi ◽  
Sayed Reza Hassan-Beygi ◽  
Hossain Ahmadian ◽  
Barat Ghobadian ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Thermodynamic Cycle ◽  
Biodiesel Production ◽  
Biodiesel Fuel ◽  
Engine Noise ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Fuel Blends ◽  
Novel Approach ◽  
Outlet Valve

In recent years, biodiesel has been demonstrated to offer a suitable level of reliability and attracted the attention of many researchers. Accordingly, various studies have been carried out to account for the biodiesel production and application, producing valuable reports and findings. In this research study, the effects of biodiesel on engine noise were studied on the basis of a time–frequency analysis. To do so, the acquired acoustic signal was initially filtered and denoised. Then the signal was transferred to the time–frequency SPL domain using short-time Fourier transform. In the A weighted signal, the SPL of all treatments were compared using an innovative visual technique. In this novel approach, the values of area percentages of the obtained SPL in the time–frequency domain were used to compare the propagated noise due to variables. The method revealed a consistent trend for all fuel blends at all engine rotational speeds. The analysis results showed that B10 (10% methyl/ethyl ester and 90% diesel fuel) and B30 had the lowest and highest A-Weighted SPL, respectively. Additionally, it was found that the engine had a maximum sensitivity for all fuel blends at an engine rotation speed of 1600 RPM. Moreover, Z-weighted (linear) signal processing was used to investigate what happens in a complete thermodynamic cycle at 1600 RPM. The developed time–frequency methodology successfully exposed all of the important acoustic events of the engine. The results of this study showed that the most effective acoustic events in engine noise were combustion, piston slap, and outlet valve closing. Furthermore, higher percentages of biodiesel blends resulted in longer combustion duration.

A Novel Approach for Seismic Time-Frequency Analysis Based on High-Order Synchrosqueezing Transform

2018 ◽  
Vol 15 (8) ◽  
pp. 1159-1163 ◽  
Author(s):  
Wei Liu ◽  
Siyuan Cao ◽  
Zhiming Wang ◽  
Kangkang Jiang ◽  
Qingchen Zhang ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
High Order ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Novel Approach ◽  
Synchrosqueezing Transform
Sign in / Sign up

Export Citation Format

Share Document