scholarly journals Frequency estimators with high resistance to interference from image frequency components

2018 ◽  
Vol 12 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Wei Zhou ◽  
Liqun Gan ◽  
Hong Xiao ◽  
Yi Zhang ◽  
Haitao Xu ◽  
...  
Keyword(s):  
Mean Squared Error ◽  
Frequency Estimation ◽  
Geometric Mean ◽  
Random Noise ◽  
Estimation Algorithm ◽  
Side Lobe ◽  
Sine Wave ◽  
Practical Engineering ◽  
Frequency Components ◽  
Image Frequency

This paper presents an improved frequency estimation algorithm based on the interpolated discrete Fourier transform. High-accurate frequency estimation can be achieved by taking the geometric mean of two independent estimates, which are derived from the real parts of the two largest spectral bins and the imaginary parts, respectively. In situations where only a small number of sine wave cycles are observed, the ability of the algorithm to cancel interference from image frequency components results in improvements in accuracy. The residual errors of the proposed algorithm have been theoretically analyzed with maximum side-lobe decaying windows, since the windows have simple and uniform analytical expression of interpolation algorithm. The performance of the proposed algorithm was investigated using both Hanning and three-term maximum side-lobe decaying windows. A comparative analysis of systematic errors and noise sensitivity was performed between the new algorithm and traditional algorithms. Both the root mean squared error and the probability density of the errors were investigated under noisy conditions. Simulation results demonstrated that the new algorithm is not only highly resistant to interference from image components but is also resistant to the effects of random noise. The results presented in the paper are useful for identifying the best choice of algorithm in practical engineering applications.

scholarly journals Barycenter Theorem in Phase Characteristics of Symmetric and Asymmetric Windows

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 329
Author(s):  
Jiufei Luo ◽  
Haitao Xu ◽  
Kai Zheng ◽  
Xinyi Li ◽  
Song Feng
Keyword(s):  
Frequency Estimation ◽  
Random Noise ◽  
Estimation Algorithm ◽  
Frequency Component ◽  
Phase Response ◽  
Numeric Simulation ◽  
Simulation Results ◽  
The Time Domain ◽  
Short Time ◽  
The Relationship

Asymmetric windows are of increasing interest to researchers because of the nonlinear and adjustable phase response, as well as alterable time delay. Short-time phase distortion can provide an essential improvement in speech coding, and also has better performance in speech recognition. The merits of asymmetric windows in the aspect of spectral behaviors have an important function in frequency component detection and parameter estimation. In this paper, the phase response of windows were further studied, and the phase characteristics of symmetric and asymmetric windows are described. The relationship between the barycenter of windows in the time domain, and the phase characteristic at the center of the main lobe in the frequency domain, was established. In light of the relationship, an improved version of the asymmetric window- based frequency estimation algorithm was proposed. The improved algorithm has advantages of straightforward implementation and computational efficiency. The numeric simulation results also indicate that the improved approach is more robust than the traditional method against additive random noise.

Study of Image Frequency Spectrum under the Different Settings of USM Parameters

2010 ◽  
Vol 174 ◽  
pp. 136-139
Author(s):  
San Guo Liu ◽  
Yang Jin ◽  
Xiu Feng Ma ◽  
Hong Jie Zhai ◽  
Zhi Gao
Keyword(s):  
High Frequency ◽  
Frequency Component ◽  
Sine Wave ◽  
Fast Fourier Transformation ◽  
Original Image ◽  
Spatial Frequencies ◽  
Spectral Components ◽  
Frequency Components ◽  
Gray Level Image ◽  
Image Frequency

To study the mechanism and functions of USM (Unsharp Masking) sharpening and to investigate its influence on image frequency component, 12 sine-wave images of different spatial frequencies are generated via a program. Then they are composed into a complete gray level image, which serves as original image for sharpening. The original image is sharpened with different parameters of USM. The original image and the sharpened images are processed using Fast Fourier Transformation (FFT) method with MATLAB software. After that, the corresponding Fourier spectral values of the 12 frequencies are extracted, the corresponding spectral value of original image is subtracted from the value of the sharpened images. The data results are finally analyzed and studied. Through the analysis of the spectrum, it indicates that the USM sharpening effect is stronger, while the USM amount and radius increase. But the effects to the spectral components are not balanced. If the USM radius is smaller but the amount is bigger, the effect to the medium and high frequency is stronger. The larger the amount of the USM sharpening and the USM radius are, the stronger the emphasis on the low and medium frequency components grows. The middle and higher frequency components are reduced, if the amount and the radius are all smaller.

scholarly journals Pharmacokinetic Modeling and Optimal Sampling Strategies for Therapeutic Drug Monitoring of Rifampin in Patients with Tuberculosis

2015 ◽  
Vol 59 (8) ◽  
pp. 4907-4913 ◽  
Author(s):  
Marieke G. G. Sturkenboom ◽  
Leonie W. Mulder ◽  
Arthur de Jager ◽  
Richard van Altena ◽  
Rob E. Aarnoutse ◽  
...  
Keyword(s):  
Population Pharmacokinetic Model ◽  
Pharmacokinetic Model ◽  
Mean Squared Error ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Therapeutic Drug ◽  
Population Pharmacokinetic ◽  
Optimal Sampling ◽  
Sampling Strategies ◽  
Wide Range

ABSTRACTRifampin, together with isoniazid, has been the backbone of the current first-line treatment of tuberculosis (TB). The ratio of the area under the concentration-time curve from 0 to 24 h (AUC0–24) to the MIC is the best predictive pharmacokinetic-pharmacodynamic parameter for determinations of efficacy. The objective of this study was to develop an optimal sampling procedure based on population pharmacokinetics to predict AUC0–24values. Patients received rifampin orally once daily as part of their anti-TB treatment. A one-compartmental pharmacokinetic population model with first-order absorption and lag time was developed using observed rifampin plasma concentrations from 55 patients. The population pharmacokinetic model was developed using an iterative two-stage Bayesian procedure and was cross-validated. Optimal sampling strategies were calculated using Monte Carlo simulation (n= 1,000). The geometric mean AUC0–24value was 41.5 (range, 13.5 to 117) mg · h/liter. The median time to maximum concentration of drug in serum (Tmax) was 2.2 h, ranging from 0.4 to 5.7 h. This wide range indicates that obtaining a concentration level at 2 h (C2) would not capture the peak concentration in a large proportion of the population. Optimal sampling using concentrations at 1, 3, and 8 h postdosing was considered clinically suitable with anr2value of 0.96, a root mean squared error value of 13.2%, and a prediction bias value of −0.4%. This study showed that the rifampin AUC0–24in TB patients can be predicted with acceptable accuracy and precision using the developed population pharmacokinetic model with optimal sampling at time points 1, 3, and 8 h.

Frequency estimation algorithm for high dynamic GPS receivers based on UKF

2007 ◽  
Author(s):  
Yunlong Zhu ◽  
Zhongkan Liu ◽  
Qishan Zhang ◽  
Dongkai Yang
Keyword(s):  
Frequency Estimation ◽  
Estimation Algorithm ◽  
Gps Receivers ◽  
High Dynamic
Sign in / Sign up

Export Citation Format

Share Document