The effect of selected rockburst prevention measures on seismic activity – Case study from the Rudna copper mine

In order to face threats from mining tremors a number of organizational and technical prevention methods are applied in underground mines. Unfortunately, most of these methods are based on the experience of crew and there is uncertainty whether in practice all of the executed operations are suitable and necessary in the given conditions. Analysis were performed for one of the mining districts of the Rudna copper mine, Poland. In this paper, selected methods of rockburst prevention in the G-4/8 district are described and the recorded seismicity is analysed. On the basis of the data provided by the personnel of the mine, maps of mining progress were generated. This permitted the mined out areas as well as backfilled excavations to be calculated as a function of time. The results were presented in quarterly periods. Furthermore, the seismicity recorded was correlated with the rate of mining progress, the rate of mined out zones and the active rockburst prevention effectiveness. Finally, it was concluded that correlation between the opening area and energy of seismic events may be observed under the mining panel conditions considered. A similar conclusion applied as regards the quarterly speed of mining and the frequency of event occurrence. Keywords: Rockburst prevention, Seismic activity, Mining-induced tremor

Factors affecting in-vivo fertility of crossbred Egyptian - Italian buffalo semen

Objective: To assess the effect of region, season and year of insemination on in-vivo fertility of Italian-Egyptian crossbred buffalo semen.Methods: A total number of 4 799 female buffaloes were inseminated by frozen semen with at least 50% post-thaw motility of Egyptian-Italian crossbred bulls in three localities in Delta, lower Egypt (El-Behira, El-Sharkia and Damietta) during the period of 2013, 2014 and 2015. The pregnancy rate after two months was evaluated during the four seasons.Results: The rate of pregnancy was significantly (P<0.000 1) differ among the three localities. The effect of year of insemination on pregnancy rate was significantly higher during 2014 and 2015 than 2013 in El-Sharkia and El-Behira. But in Damietta, the rate of pregnancy was significantly higher in 2014 than 2013 and 2015. There were no significant differences among seasons in El-Behira and Damietta governorates but there was significant (P<0.05) differences in pregnancy rate in El-Sharkia. It was higher in summer, spring and autumn than in winter.Conclusions: Localities, year of insemination and season of the year have effects on fertility of crossbred Egyptian-Italian buffalo semen