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Frequency-Selective Robust Detection and Estimation of Multiple-Polymorph QR Signals

Butt, Naveed LU ; Somasundaram, Samuel D.; Jakobsson, Andreas LU and Smith, John A. S. (2008) In Signal Processing 88(4). p.834-843
Abstract
Nuclear quadrupole resonance (NQR) is a non-invasive, solid state, radio frequency (RF) technique, able to distinguish between polymorphic forms of certain compounds. Exploiting the signals from multiple polymorphs is important in explosives detection, whilst quantifying these polymorphs is important in pharmaceutical applications. Recently proposed hybrid algorithms, able to process the signals from multiple polymorphs, assume that the amplitudes associated with each polymorph are known to be within a scaling. Any error in this a priori information will lead to performance degradation in these algorithms. In this paper, we develop a robust hybrid algorithm allowing for uncertainties in the assumed amplitudes, extending a recently proposed... (More)
Nuclear quadrupole resonance (NQR) is a non-invasive, solid state, radio frequency (RF) technique, able to distinguish between polymorphic forms of certain compounds. Exploiting the signals from multiple polymorphs is important in explosives detection, whilst quantifying these polymorphs is important in pharmaceutical applications. Recently proposed hybrid algorithms, able to process the signals from multiple polymorphs, assume that the amplitudes associated with each polymorph are known to be within a scaling. Any error in this a priori information will lead to performance degradation in these algorithms. In this paper, we develop a robust hybrid algorithm allowing for uncertainties in the assumed amplitudes, extending a recently proposed robust algorithm, formulated for single polymorphs, to process signals from multiple polymorphs. In the proposed robust algorithm, the amplitudes are allowed to vary within an uncertainty hyper-sphere whose radius is evaluated using analytical expressions derived herein. Extensive numerical investigations indicate that the proposed algorithm provides significant performance gains as compared to both the existing hybrid algorithms, when uncertainties in the amplitudes exist, and the existing robust algorithm, when there are multiple polymorphs. Finally, the Cramér–Rao lower bound is derived for the uncertain data case as a reference for the quantification problem. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Nuclear quadrupole resonance, Constrained least squares, Explosives detection
in
Signal Processing
volume
88
issue
4
pages
834 - 843
publisher
Elsevier
external identifiers
  • scopus:37649012160
ISSN
0165-1684
DOI
10.1016/j.sigpro.2007.09.021
language
English
LU publication?
no
id
1321afc4-94e4-4cc5-be14-674b7cedeacf (old id 1216199)
date added to LUP
2008-10-06 15:42:29
date last changed
2017-01-01 05:25:01
@article{1321afc4-94e4-4cc5-be14-674b7cedeacf,
  abstract     = {Nuclear quadrupole resonance (NQR) is a non-invasive, solid state, radio frequency (RF) technique, able to distinguish between polymorphic forms of certain compounds. Exploiting the signals from multiple polymorphs is important in explosives detection, whilst quantifying these polymorphs is important in pharmaceutical applications. Recently proposed hybrid algorithms, able to process the signals from multiple polymorphs, assume that the amplitudes associated with each polymorph are known to be within a scaling. Any error in this a priori information will lead to performance degradation in these algorithms. In this paper, we develop a robust hybrid algorithm allowing for uncertainties in the assumed amplitudes, extending a recently proposed robust algorithm, formulated for single polymorphs, to process signals from multiple polymorphs. In the proposed robust algorithm, the amplitudes are allowed to vary within an uncertainty hyper-sphere whose radius is evaluated using analytical expressions derived herein. Extensive numerical investigations indicate that the proposed algorithm provides significant performance gains as compared to both the existing hybrid algorithms, when uncertainties in the amplitudes exist, and the existing robust algorithm, when there are multiple polymorphs. Finally, the Cramér–Rao lower bound is derived for the uncertain data case as a reference for the quantification problem.},
  author       = {Butt, Naveed and Somasundaram, Samuel D. and Jakobsson, Andreas and Smith, John A. S.},
  issn         = {0165-1684},
  keyword      = {Nuclear quadrupole resonance,Constrained least squares,Explosives detection},
  language     = {eng},
  number       = {4},
  pages        = {834--843},
  publisher    = {Elsevier},
  series       = {Signal Processing},
  title        = {Frequency-Selective Robust Detection and Estimation of Multiple-Polymorph QR Signals},
  url          = {http://dx.doi.org/10.1016/j.sigpro.2007.09.021},
  volume       = {88},
  year         = {2008},
}