In the paper, the authors discuss the numerical and experimental modal analysis of the cantilever thin-walled beams made of a carbon-epoxy laminate. Two types of beams were considered: circumferentially asymmetric stiffness (i.e., CAS) and circumferentially uniform stiffness (i.e., CUS) beams. The layer-up configurations of the laminate were chosen to get a vibration mode coupling effect in both analysed cases. The aim of the paper was to perform the numerical and experimental modal analysis of the composite structures, when a flapwise bending with torsion coupling effect or flapwise-chordwise bending coupling effect took place. Firstly, numerical studies by the finite element method was performed. The numerical simulations were carried out by the Lanczos method in the Abaqus software package. The natural frequencies and the corresponding free vibration modes were determined. Next, the experimental modal analyses of the CAS and CUS beams were performed. The test stand was consisted of a special grip, two beams with an adhered holder, the LMS Scadas III system with a modal hammer and an acceleration sensor. Finally, the results of both methods were compared.
Agriculture is a signifi cant source of gaseous pollutants such as ammonia, methane, nitrous oxide and volatile organic compounds. Ammonia is particularly important due to the high emission and local, as well as global impact on the environment. The release of NH3 is one of the main ways of nitrogen emission to the atmosphere and it contributes to its subsequent deposition. The aim of the study was to analyze ammonia emissions from animal production in Poland in 2005–2017, its regional diversity and possibilities of its reduction in agriculture. The ammonia emission was calculated for the animal production groups according to the NFR classifi cation. The values of ammonia emission were calculated based on ammonia emission factors used by KOBIZE, in accordance with the EMEP/EEA methods. In 2017, the NH3 emission from Polish agriculture amounted 288 Gg and it accounted for 96% of the emission in 2005. Ammonia emission from livestock production, in 2005–2017, on average accounted for 79.8% of agricultural emissions. The largest share had the cattle (51%) and swine (30%) production. The NH3 emissions differed strongly between provinces. The emission density (kg NH3·km-2·year-1) in provinces with intensive livestock production was about 5.5 times higher than in regions, where livestock production was the lowest. The mitigation strategies should be implemented primarily in provinces where reduction potential is the largest. The assessment of the reduction potential should take into account the NH3 emission per 1 km2 and the low
NH3 emission technologies, which are already applied in the regions.