Evidential value of duct tape comparison using loopbreaking patterns.

A new method for the evaluation of duct tape ends is proposed. This method is based on the breaks of the loops in the warp yarns, when duct tape with a scrim of chain-stitched warp yarns and weft-insertion is torn. After tearing, the loop at the end of each warp yarn can be in one of four states: open, closed, complex or missing. Additionally, the horizontal position of each warp yarn can be expressed in terms of weft yarns. The evidential strength of these loopbreaking patterns is expressed in terms of likelihood ratios. We construct a likelihood ratio system to determine these likelihood ratios. This consists of three dynamic Bayesian networks, which are based on the main assumption that the loopbreaking patterns are a stochastic process which comply to the Markov property. A dataset is used to train and test the LR-system. Based on these results, it is found that the loopbreaking patterns contain very strong evidence. More data, especially on observation errors, is needed to evaluate the system further.