Magnus Mossberg

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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 the means to improve the SNR are vital to enable a rapid, reliable, and convenient system. In this paper, an approximate maximum-likelihood detector (AML)(More)
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)
The problem of optimal sensor locations in nonparametric identification of viscoelastic materials is considered. Different criteria of the covariance matrix, connected to Aand 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.
The problem of estimating the parameters in stochastic continuous-time signals, represented as continuous-time autoregressive moving average (ARMA) processes, from discrete-time data is considered. The proposed solution is to fit the covariance function of the process, parameterized by the unknown parameters, to sample covariances. It is shown that the(More)
We investigate how the frequency-dependent wave propagation coe$cient and complex modulus for a linearly viscoelastic material can be estimated from wave propagation experiments. The strains at di!erent sections of a bar specimen are measured as functions of time. The time series are transformed into the frequency domain, where a non-parametric(More)