The aim of this paper is to describe a new discrete method for the evaluation of local damage to the bearing system of underground structures. The discrete boundary element method, which serves as a numerical means for detecting local cracks, has been used in the past either as a general means for identifying sites with cracks or for assessing the possibility of bumps occurring in underground mines. Newly, this method is non-trivially extended to the combination with non-linear Navier-Stokes equations, which are solved by finite volumes used to describe the propagation of air movement that creates a subsonic pressure wave in the free space within the structure. Interaction of waves along the boundary of both phases is ensured by interfacial conditions, which correspond to the combination of both numerical means - discontinuous boundary elements and finite volumes. To maintain compatibility of both environments, discretization of both air and solid is based on hexagonal meshes. Two typical examples demonstrate the suitability of the method showing an initial (critical) state of the development of pressure waves and the condition of damage to the structures of underground parking.
The genetic variation in low temperature sensitivity of eight tomato genotypes grown at suboptimal temperature (19 °C) and at low irradiance (140 pmol m'2 s**) was assessed at the plant, chloroplast and thylakoid membrane levels. Temperature effects on the thylakoid membrane were determined by measuring the maximum fluorescence (Fp) and the maximal fluorescence rise (ADP) of induction traces of leaf discs at decreasing temperatures (30, 28, ... 0 °C). Two discontinuities were found in Fp versus temperature curves: a low temperature break at ca. 12 °C (LTB) and a high temperature break at ca. 22 °C (FITB). Below LTB, sFp and sDP were determined as the temperature induced changes in Fp, respectively ADP. Chloroplast functioning was determined by measuring net CO2 fixation rate (E^) of leaves. Plant performance was determined by measuring the increase in leaf area and sho ot dry mass in time. Correlations between the various parameters were analysed across the genotypic variation found. Chlorophyll (Chl) fluorescence parameters were not correlated with plant performance at suboptimal growth conditions. of leaves was correlated with plant performance, but only at ambient CO2. Effects of stomatal resistance on were large. The Chl fluorescence parameters LTB, sFp and sDP could distinguish between tomato genotypes. Nevertheless, the ranking of the genotypes depended on the specific parameter selected, indicating that each parameter assessed a different aspect of the heterogeneous temperature dependence of Chl fluorescence induction. Their genetic variation suggested that the genotypes differed in the organisation and fimctioning of the thylakoid membrane. These differences were not reflected in of leaves or plant performance.