Rhammatocerus schistocercoides locust outbreaks in Mato Grosso (Brazil): A long-standing phenomenon
Evidence obtained orally or from publications clearly indicate that Rhammutocerus schistocercoides Rehn, 1906 (Orthoptera: Acrididae Gomphocerinae) outbreaks in Mato Grosso (Brazil) are a long-standing phenomenon, both in terms of their extent and nature. Current theories on the origins of these outbreaks therefore must be drastically revised, especially those that blame the accelerated agricultural development that has occurred in these regions since 1980.
Identity of Rhammatocerus schistocercoides (Rehn, 1906) forms south and north of the Amazonian rain forest and new hypotheses on the outbreaks determinism and dynamics
Brazil, Colombia and Venezuela have, for several years, been facing severe outbreaks in species belonging to the genus #Rhammatocerus#. This genus is in need of revision and until now it was not certain that the populations involved North and South of the amazonian rain forest belonged to the same species or not. Our studies show that, in fact, a single species with a large distribution area is involved : #R. schistocercoides# (Rehn, 1906). Biological data, the dynamic of the invasions and hypotheses on the outbreak determinism in the Northern and Southern parts of the distribution area are synthesized and discussed. (Resume d'auteur)
Experimental study on bond behavior between high-strength grout and deformed steel bars
Abstract Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model.