Yielding support, commonly applied to secure dog headings, is made of carrying elements in the form of steel frames and friction props. Yielding capacity of this support is realized in frictional joints, which due to their geometry can be divided to straight and arch joints. Occurring in steel frames arch frictional joints are characterized with more complex loading state than straight joints used in friction props. In the article, there is presented an analysis of the state of stress and deformation of the arch frictional joint, which was carried out on the model of these joints using finite element method. The scope of the analysis included two methods of loading of arch frictional joint, namely its axial compression and bending. In both cases, joints were loaded dynamically with the impact of freely falling mass. Arch joints with and without passive pressure were submitted to an axial compression. Physical model of the frictional joint was developed on the basis of a system applied during the stand tests. To solve mathematical model an explicit integration method was used. As a result of analyses carried out, temporal courses of force transmitted through the frictional joint, and displacements of section sliding down were determined. On the basis of the temporal courses, dependences between maximum value of force transmitted through the frictional joint and the height from which the impact mass falls down were determined. Distributions of reduced stresses in elements of frictional joint were also determined and the state of deformation was described. In order to emphasize the difference between straight and arch frictional joints, also an analysis of internal forces in arch frictional joint depending on its geometrical parameters without and with passive pressure was presented.
Mirosław Wierzbicki, Norbert Skoczylas and Mateusz Kudasik
The unipore methane diffusion model based on the solution of the second Fick’s law describes effectively the kinetics of methane release from coal grains. The knowledge of the model describing the kinetics of methane release from coal, the coalbed methane content, the sorption isotherm, the effective diffusion coefficient and the coal particle size distribution, enables the calculation of the volume of methane which is released from the coal spoil as a function of time. These assumptions became the basis for building the software that enables the analysis of methane emissions from coal during the longwall mining. Simulations were performed to determine the temporal and spatial methane inflow to the longwall. The share of methane emission from coal grains (taking into account both the emission kinetics and mass participation) of various classes has been analyzed. The results of the analysis showed that the methane from the small grains, in particular less than 0.1 mm in size, prevails. The mass fraction of these grains in the total weight does not exceed 5%. For the typical parameters determining the mining, geological and technological conditions of methane emissions at different moments of time and position of the longwall were determined.
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Aref M. Al-Swaidani, Ibraheem Hamood and Ayman Meziab
and lime additives on the temporal variation of soil compaction and shear strength. Front Earth Science 5 (2): 162&169. 10.1007/s11707-011-0166-1 .
Harichane K. Ghrici M. Missoum H. 2011 Influence of natural pozzolana and lime additives on the temporal variation of soil compaction and shear strength Front Earth Science 5 2 162 169 10.1007/s11707-011-0166-1
 Zoubir, W., Harichane, K., Ghrici, M. (2013). Effect of lime and natural pozzolana on dredged sludge engineering properties. EJGE 18 589&600.
Zoubir W. Harichane K
Iman Faridmehr, Mohammad Reza YazdaniPour, Mohammad Javadi Jokar and Togay Ozbakkaloglu
Variation of piezometric pore-water surface resulted from instrumentation.
6.4 Analysis Results for the Transient Flow Condition
The flow of water in unsaturated soils may vary both spatially and temporally due to several factors. Time-dependent changes in the boundary conditions (infiltration-evaporation) can significantly influence the flow mechanism. Such changes are accounted for by the theoretical models by considering these changes in terms of boundary conditions for the soil domain. Fig. 14 shows the pressure