| 1. |
|
|
| 2. |
- Khan, Nabeel Ali, et al.
(författare)
-
Iterative missing data recovery algorithm for non-stationary signals
- 2022
-
Ingår i: Signal, Image and Video Processing. - : Springer Science and Business Media LLC. - 1863-1703 .- 1863-1711. ; 16:7, s. 1731-1738
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes an iterative algorithm to reconstruct missing samples from non-stationary signals. The proposed algorithm is based on the well-known amplitude-modulation frequency-modulation model for non-stationary signals. The method initially estimates the instantaneous frequencies of the observed multi-component signal. The estimated IFs are then used to de-chirp the corresponding components to convert them into stationary components. Following this, a relatively recent nonparametric iterative missing data recovery procedure is employed to reconstruct the time-varying amplitudes of the signal components. The complete signal is constructed by adding all the estimated components, which is used as an input signal to re-estimate the IFs and time-varying amplitudes in an iterative procedure. Studies based on simulated and real data sets show that the proposed approach provides better estimates as compared to the state of the art.
|
|
| 3. |
- Khan, Nabeel Ali, et al.
(författare)
-
Performance comparison of time-frequency distributions for estimation of instantaneous frequency of heart rate variability signals
- 2017
-
Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417 .- 1454-5101. ; 7:3
-
Tidskriftsartikel (refereegranskat)abstract
- The instantaneous frequency (IF) of a non-stationary signal is usually estimated from a time-frequency distribution (TFD). The IF of heart rate variability (HRV) is an important parameter because the power in a frequency band around the IF can be used for the interpretation and analysis of the respiratory rate but also for a more accurate analysis of heart rate (HR) signals. In this study, we compare the performance of five states of the art kernel-based time-frequency distributions (TFDs) in terms of their ability to accurately estimate the IF of HR signals. The selected TFDs include three widely used fixed kernel methods: the modified B distribution, the S-method and the spectrogram; and two adaptive kernel methods: the adaptive optimal kernel TFD and the recently developed adaptive directional TFD. The IF of the respiratory signal, which is usually easier to estimate as the respiratory signal is a mono-component with small amplitude variations with time, is used as a reference to examine the accuracy of the HRV IF estimates. Experimental results indicate that the most reliable estimates are obtained using the adaptive directional TFD in comparison to other commonly used methods such as the adaptive optimal kernel TFD and the modified B distribution.
|
|
| 4. |
- Khan, Nabeel Ali, et al.
(författare)
-
Time-frequency image enhancement based on interference suppression in Wigner-Ville distribution
- 2016
-
Ingår i: Signal Processing. - : Elsevier BV. - 0165-1684. ; 127, s. 80-85
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a time-frequency (t-f) image enhancement method for suppressing interference terms in the Wigner-Ville distribution. The proposed technique adapts the direction of the smoothing kernel locally at each t-f point, so that the smoothing kernel remains aligned with the ridges of the auto-terms. This local alignment of the smoothing kernel reduces cross-terms without degrading the energy concentration of auto-terms. The results indicate that the proposed time-frequency distribution outperforms other methods in terms of its ability to resolve close signal components.
|
|
| 5. |
- Peden, John F., et al.
(författare)
-
A genome-wide association study in Europeans and South Asians identifies five new loci for coronary artery disease
- 2011
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 43:4, s. 339-344
-
Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies have identified 11 common variants convincingly associated with coronary artery disease (CAD)(1-7), a modest number considering the apparent heritability of CAD(8). All of these variants have been discovered in European populations. We report a meta-analysis of four large genome-wide association studies of CAD, with similar to 575,000 genotyped SNPs in a discovery dataset comprising 15,420 individuals with CAD (cases) (8,424 Europeans and 6,996 South Asians) and 15,062 controls. There was little evidence for ancestry-specific associations, supporting the use of combined analyses. Replication in an independent sample of 21,408 cases and 19,185 controls identified five loci newly associated with CAD (P < 5 x 10(-8) in the combined discovery and replication analysis): LIPA on 10q23, PDGFD on 11q22, ADAMTS7-MORF4L1 on 15q25, a gene rich locus on 7q22 and KIAA1462 on 10p11. The CAD-associated SNP in the PDGFD locus showed tissue-specific cis expression quantitative trait locus effects. These findings implicate new pathways for CAD susceptibility.
|
|
