OPERATIONAL PERFORMANCE OF AN AGRICULTURAL TRACTOR UNDER DIFFERENT TIRE INFLATION PRESSURES IN THE SUBSOILING OPERATION

For the agricultural tractor's best performance, it must be correctly adapted to the job. Among other factors, the adequacy of tire inflation pressure is one of the most important and may influence the operation's efficiency and productivity. This study aimed to evaluate an agricultural tractor's operational performance with different tire inflation pressures in the subsoiling operation. The study was carried out in an experimental area of the Agricultural Machinery and Mechanization Laboratory of the experimental farm “Água Limpa,” belonging to the University of Brasília. The experimental design used was in randomized blocks with the following values, 206.8 kPa (30 psi), 137.9 kPa (20 psi), and 68.9 kPa (10 psi), of inflation pressure for agricultural tractor tires. The mechanized set used was a tractor model TM7020 2WD MFWD pulling a subsoiler with five shanks, SPCR model, in a Latossolo Vermelho-Amarelo. The higher inflation pressure resulted in greater slippage, advance, hourly fuel consumption, and lower speed and operational field capacity

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements