ABSTRACT The largest proportion of greenhouse gas (GHG) emissions in the Agriculture sector of the Brazilian national GHG inventory is derived from the large (>200 million head) herd of cattle. The greatest contribution to these emissions comes from the enteric methane from cattle, but the direct and indirect emissions of nitrous oxide (N2O) from cattle excreta and N fertilizer are responsible for approximately 9 % of all national anthropogenic GHG emissions. Ammonia (NH3) can be volatilized from N fertilizer and cattle excreta and deposited in sites remote from the source, constituting an indirect source of N2O. This study aimed to determine whether direct N2O emissions and NH3 volatilization from N-fertilized pastures were greater than those derived from a mixed grass-legume pasture without N fertilizer addition. Emissions of N2O and NH3 from excreta and N fertilizer from a Palisade grass (Urochloa brizantha cv. Marandu) monoculture fertilized with 2 × 60 kg N ha-1 yr-1 urea were compared to those from a mixed Palisade grass-forage peanut (Arachis pintoi) pasture. Dung and urine were collected from these cattle, and NH3 losses and N2O emissions from the excreta and from N fertilizer were monitored using static chamber techniques. Volatilization of NH3 and N2O emissions were found to be greater from urine than from dung. Ammonia losses from excreta and urea fertilizer were low, not exceeding 6.8, 1.1, and 4.7 % of the N applied as urine, dung, and fertilizer, respectively. The N2O emissions showed a tendency to be greater for the urine from the N-fertilized compared to the mixed grass-legume pasture, and the N2O emissions from the urine of the N-fertilized pasture ranged from 0.08 to 0.94 % of applied urine N. The N2O emission from the N fertilizer was at maximum 0.46 % of the applied N. The direct N2O emissions and the loss of NH3 by volatilization (indirect N2O emission) from the excreta of cattle grazing the mixed grass-legume pasture were similar to, or lower than, the grazed grass monoculture fertilized with 120 kg N ha-1 yr-1. As the mixed pasture received no N fertilizer and hence no GHG emission from its manufacture or application, introducing forage peanut to the Urochloa brizantha pastures shows potential to be responsible for lower GHG emissions than the N fertilized grass pasture. (GHG >200 200 (>20 head NO O (N2O NH (NH3 Nfertilized grasslegume legume addition cv Marandu 6 ha1 ha 1 ha- yr1 yr yr- grassforage Arachis pintoi techniques dung low 68 8 6.8 11 1.1 47 4 7 4. respectively 008 0 08 0.0 094 94 0.9 046 46 0.4 12 yr1. 1. application >20 20 (>2 (NH 6. 00 0. 09 04 >2 (> > (

Abstract The analytical approach is presented for both symmetric and anti-symmetric local buckling of the thin-plate in finite sizes and with a center crack under tension. An efficient classical solution based on the principle of minimum total potential energy was provided using only 2 and 1 degrees of freedom for symmetric and anti-symmetric modes and the linear elastic buckling loads are evaluated by the means of Rayleigh-Ritz method. In the pre-buckling state, a correction factor for the peak compressive stress in the finite cracked plates is defined with an empirical formula and used in the analytical solution of the buckling. To verify the analytical approach, a wide range of numerical results by aid of finite element method are provided herein and a comparison between theoretical results with the experimental work of other researchers has been done. Both numerical and experimental results accept the accuracy and validity of the presented analytical model.

An experimental procedure is carried out to investigate response features of semi-deep reinforced concrete (RC) beams with dominant static shear failure subjected to low-velocity impact dynamic load both in intact and retrofitted cases. Built specimens have scaled geometry and material properties preserving physical similarity with full-scale members and are strengthened using externally bonded carbon fiber reinforced polymer (CFRP) sheets. Conducted tests gather reliable and robust data revealing notable stiffness and strength recovery within skin attachment. Desired performance criterion is detected here as concrete flexural cracking along span only when brittle shear collapse is prevented. Peak absorbed impulse capacity is attained for unidirectional carbon fiber retrofit. Stiffness is recovered initially during first impacts and then starts degrading due to rupture of horizontal fibers in cross-ply retrofit, but provided stiffness is stable for unidirectional retrofit during all impacts.