scholarly journals Comparative Study of AC Signal Analysis Methods for Impedance Spectroscopy Implementation in Embedded Systems

2022 ◽  
Vol 12 (2) ◽  
pp. 591
Author(s):  
Ahmed Yahia Kallel ◽  
Zheng Hu ◽  
Olfa Kanoun

For embedded impedance spectroscopy, a suitable method for analyzing AC signals needs to be carefully chosen to overcome limited processing capability and memory availability. This paper compares various methods, including the fast Fourier transform (FFT), the FFT with barycenter correction, the FFT with windowing, the Goertzel filter, the discrete-time Fourier transform (DTFT), and sine fitting using linear or nonlinear least squares, and cross-correlation, for analyzing AC signals in terms of speed, memory requirements, amplitude measurement accuracy, and phase measurement accuracy. These methods are implemented in reference systems with and without hardware acceleration for validation. The investigation results show that the Goertzel algorithm has the best overall performance when hardware acceleration is excluded or in the case of memory constraints. In implementations with hardware acceleration, the FFT with barycentre correction stands out. The linear sine fitting method provides the most accurate amplitude and phase determinations at the expense of speed and memory requirements.

2008 ◽  
Vol 381-382 ◽  
pp. 247-250
Author(s):  
Ming Wang ◽  
Dong Mei Guo

In order to improve the displacement measurement accuracy of the laser diode self-mixing interference (SMI), phase measurement method is introduced in the SMI signal analysis. In this paper, three modulation technique have been proposed: injection current modulation, external cavity length modulation and sinusoidal phase modulation. Measurement principle of the three modulation techinque are briefly explained. Design of the experimental system, measurement results of micro-displacement will be reported.


2015 ◽  
Vol 12 (2) ◽  
pp. 13
Author(s):  
Muhamad Faridz Osman ◽  
Karimah Kassim

The coordination complexes of Co(II) and Zn(II) with Schiff bases derived from o-phenylenediamine and substituted 2-hydroxybenzaldehyde were prepared All compounds were characterized by Fourier transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) spectroscopy elemental analyzers. They were analyzed using impedance spectroscopy in the frequency range of 100Hz-1 MHz. LI and L2 showed higher conductivity compared to their metal complexes, which had values of 1.3 7 x 10-7 and 6.13 x 10-8 S/cm respectively. 


2022 ◽  
Vol 10 (1) ◽  
pp. 102
Author(s):  
Zhiyao Zhu ◽  
Huilong Ren ◽  
Xiuhuan Wang ◽  
Nan Zhao ◽  
Chenfeng Li

The limit state function is important for the assessment of the longitudinal strength of damaged ships under combined bending moments in severe waves. As the limit state function cannot be obtained directly, the common approach is to calculate the results for the residual strength and approximate the limit state function by fitting, for which various methods have been proposed. In this study, four commonly used fitting methods are investigated: namely, the least-squares method, the moving least-squares method, the radial basis function neural network method, and the weighted piecewise fitting method. These fitting methods are adopted to fit the limit state functions of four typically sample distribution models as well as a damaged tanker and damaged bulk carrier. The residual strength of a damaged ship is obtained by an improved Smith method that accounts for the rotation of the neutral axis. Analysis of the results shows the accuracy of the linear least-squares method and nonlinear least-squares method, which are most commonly used by researchers, is relatively poor, while the weighted piecewise fitting method is the better choice for all investigated combined-bending conditions.


Author(s):  
Yu Wang ◽  
Ruiwei Li ◽  
Lin Luo ◽  
Lin Ruan

The application of elbow flowmeter in rotary equipments is beneficial to reduce the pipeline complexity. However, the intervention of centrifugal acceleration will lead to the change of metrological characteristics of elbow flowmeter. Based on the analysis of the differential pressure formation mechanism of the environmental acceleration on the elbow flowmeter, the calculation formula of the flow rate measurement with the elbow flowmeter in the rotating state is derived, and the fitting method of the discharge coefficient is put forward. The CFD method was used to analyze the internal flow field of the elbow flowmeter under rotating state, summarize the pressure distribution characteristics of the pipe wall, and verify the feasibility of the discharge coefficient fitting strategy by simulation. The results show that for the elbow flowmeters with diameters of 10 mm and 15 mm and the radius to diameter ratio of 1.5, as long as the water flow rate is between 1.5 m/s and 5 m/s, the measurement accuracy can be guaranteed to be above 4%.


1982 ◽  
Vol 36 (4) ◽  
pp. 401-404 ◽  
Author(s):  
P. C. Gillette ◽  
J. B. Lando ◽  
J. L. Koenig

The application of a finite difference Levenberg-Marquardt nonlinear least-squares procedure for the resoluton of overlapping peaks in Fourier transform-infrared spectra is described. Starting estimates of peak parameters utilized in the refinement are obtained from a numerically approximated second derivative spectrum which has been smoothed. Quantitative information reflecting the constituent peaks and the “goodness of fit” is displayed graphically in a procedure requiring much less than 1 min to both initiate and obtain results in a form that is readily interpreted.


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