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A novel procedure for damage identification of framed structures is proposed, where both the location and the extent of structural damage in framed structures can be correctly determined using only a limited number of measured natural frequencies. No knowledge of the modal shapes of the damaged structure is required. On the basis of the characteristic equations for the original and the damaged structure, a set of equations is generated. Two computational techniques, the direct iteration (DI) technique and the Gauss-Newton least-squares (GNLS) technique, are utilized to determine structural damage from the derived equations. Finally, different numerical examples are used to demonstrate the effectiveness of the proposed method.

Abstract. Dispersal has been least understood in mountain pine beetle ecology. We developed a novel regional dynamic conceptual model of mountain pine beetle infestation using the tree mortality estimated from the British Columbia annual aerial overview survey to quantitatively determine short-distance dispersal (SDD) and long-distance dispersal (LDD) at local (forest district) and regional (provincial) scales. The dispersal patterns were characterized based on distances between a sink patch to its nearest source patch. At the regional scale, SDD accounted for 85.3% of mountain pine beetle dispersal to non-infested areas and 96.8% of beetle dispersal to infested areas. Although SDD was a dominant dispersal mode, LDD played a more important role in the early stage of the current mountain pine beetle outbreak. At the local scale, three patterns of dispersal to non-infested areas were identified. First, LDD dominated in the forest districts where only sparse infestations occurred. Second, LDD was a dominant or important factor in the early stages of the infestations in some districts. Third, SDD dominated throughout the infestations in more severely infested forest districts. However, for dispersal to infested areas, SDD was a dominant mode in most of the forest districts. We conclude from the spatiotemporal patterns of dispersal observed at local and regional scales that LDD is a key factor in the initiation and early stage of the infestations in new remote areas, and SDD dominate in the spread and expansion of the outbreak as the infestations intensify and reach epidemic levels. However, it should be conscious that there is uncertainty that LDD might have been over emphasized in the dispersal before local dynamics is fully taken into account.

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Short fiber-reinforced semi-solid fresh cement pastes and mortars, tailored for extrusion, have much lower water-to-binder ratio and higher viscosity than normal cement pastes or mortars. The rheology of these pastes or mortars cannot be characterised by traditional rheology test methods suitable for normal fresh cement pastes or mortars with much greater water-to-binder ratio and lower viscosity. In this paper, orifice extrusion is employed to calibrate rheology of the semi-solid fresh cement mortar. An analytical model is developed for orifice extrusion of semi-solid pastes and mortars obeying a rigid-viscoplastic constitutive relationship, von-Mises yield criterion and the associated flow rule. Orifice extrusion results are interpreted using the analytical model and the established experiment data interpretation method and the associated rheological parameters are derived for the semisolid fresh cement mortar. This study provides a simple analytical model, together with experiment and data interpretation methods, for characterizing the complex intrinsic rheological behaviour of semi-solid fresh cement pastes or mortars.