The complex modulus of a material with linearly viscoelastic behaviour is identi"ed on the basis of strains which are known, from measurements and sometimes from a free end boundary condition, at three or more sections of an axially impacted bar specimen. The aim is to improve existing identi"cation methods based on known strains at three uniformly… (More)
Nuclear Quadrupole Resonance (NQR) offers an unequivocal method of detecting and identifying land mines. Unfortunately , the practical use of NQR is restricted by the low signal to noise ratio (SNR), and means to improve the SNR are vital to enable a rapid, reliable and convenient system. In this paper, we develop a non-linear least squares detector… (More)
The problem of optimal sensor locations in nonparametric identification of viscoelastic materials is considered. Different criteria of the covariance matrix, connected to A-and D-optimal experiment design, are considered and evaluated. The results of the paper can be used to design experiments with improved accuracy of the estimates.