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This paper analyses the impacts of the growth of renewable energy production and German nuclear phase-out on the electricity transmission systems in Central Europe. The principal concern is the significant disparity between the growth of renewable production and the pace at which new transmission lines for the transport of electricity have been built, especially in Germany. This imbalance profoundly endangers the system stability and reliability in the whole region. The assessment of these impacts on the transmission grid is analysed by the direct current load flow model ELMOD. Two development scenarios for the year 2025 are evaluated by 3 representative weeks. The results illustrate the issue from three different perspectives. First, the distribution of loads in the grids is shown. Second, hourly patterns during particular weeks are analysed. Third, a geographical decomposition is made, and problematic regions are identified. The high solar or wind power generation decrease the periods of very low transmission load and increase the mid- and high load on the transmission lines. High solar feed-in has less detrimental impacts on the transmission grid than high wind feed-in. High wind feed-in burdens the transmission lines in the north-south direction in Germany and water-pump-storage areas in Austria.

ABSTRACTThe voices of 8 hinds and their 7 offspring were analysed spectrographically. They were transformed into sonograms and the following parameters were measured: duration, fundamental frequency and frequency bands with high amplitudes. The animals emitted single calls or a series of sounds at irregular intervals. The single calls were monosyllabic and the series were homotypical sequences. The hind voices were deep and bleatlike, ranging in frequency from 70 to 3000 Hz. The fundamental frequency was 108.35 ± 15.21 Hz and the duration was 0.27 ±0.14 sec. There were 1 to 8 frequency bands with high amplitudes created. Differences between individual voices were found in all characteristics of vocalization tested. The variation between voices was a result of the combination of these characteristics. The most important factor seemed to be the pattern of main frequency bands with high amplitudes. The calf voices were high, whiny and tonal, ranging in frequency from 320 to 7000 Hz. The fundamental frequency was 736.97 ± 177.67 Hz and the duration was 0.26 ± 0.12 sec. They were similar to each other, and inter-individual variation was not very apparent. This suggests that while hinds can be recognized individually by voice, it is probably not possible to distinguish the calves by voice alone. This is in accordance with parallel findings, that hinds did not seem to recognise their own calfs voice.

Eleven hinds and their calves were observed on a deer farm in order to study their vocal communication. Red deer calves are ‘hiders’, and therefore it was believed that they would need to recognize their mother's voice, but the hinds would not need to recognize the voice of their offspring. The following predictions were tested. First, the calf can recognize its mother by voice. Second, the hind's ability to recognize her calf by voice is less pronounced. The study had two parts. Part I was focused on spontaneous behaviour of the animals. Part II involved experiments with audio recordings. It was observed that the hinds vocalized more frequently than the calves, and it appeared that the vocalization served primarily a contact function. The calves seemed to recognize their mothers' voice better than vice versa. For the hinds, vision was more important than hearing. Thus, the predictions were confirmed.