The role of remote wind forcing in the subinertial current variability in the central and northern parts of the South Brazil Bight

Data analysis of continental shelf currents and coastal sea level, together with the application of a semi-analytical model, are used to estimate the importance of remote wind forcing on the subinertial variability of the current in the central and northern areas of the South Brazil Bight. Results from both the data analysis and from the semi-analytical model are robust in showing subinertial variability that propagates along-shelf leaving the coast to the left in accordance with theoretical studies of Continental Shelf Waves (CSW). Both the subinertial variability observed in along-shelf currents and sea level oscillations present different propagation speeds for the narrow northern part of the SBB (~?6–7 m/s) and the wide central SBB region (~?11 m/s), those estimates being in agreement with the modeled CSW propagation speed. On the inner and middle shelf, observed along-shelf subinertial currents show higher correlation coefficients with the winds located southward and earlier in time than with the local wind at the current meter mooring position and at the time of measurement. The inclusion of the remote (located southwestward) wind forcing improves the prediction of the subinertial currents when compared to the currents forced only by the local wind, since the along-shelf-modeled currents present correlation coefficients with observed along-shelf currents up to 20% higher on the inner and middle shelf when the remote wind is included. For most of the outer shelf, on the other hand, this is not observed since usually, the correlation between the currents and the synoptic winds is not statistically significant.     

Simplified procedure for the estimation of local inelastic deformation demands for seismic performance assessment of buildings

The implementation of performance‐based design and assessment procedures in seismic codes leads to the need for an accurate estimation of local component demands. According to Part 3 of Eurocode 8 safety checks should be always conducted in terms of plastic rotations, even when linear elastic methods of analysis are used. This paper demonstrates that linear analysis fails to predict inelastic deformation demands at the member level. Therefore, a simplified procedure that allows for the estimation of beam inelastic deformation demands using linear elastic methods of analysis in a simple and conservative way is presented herein. A number of moment‐resisting steel frames designed according to different criteria and exhibiting different column‐to‐beam strength ratios were analysed and used for the derivation of the proposed procedure. A comparative study between alternative methods of quantifying inelastic deformation demands using linear analysis is also carried out. The results obtained allow concluding about the efficiency and conservativeness of the proposed procedure which makes it attractive to be employed in engineering practice. Copyright © 2016 John Wiley & Sons, Ltd.     

Decentralized water supply by reservoir network reduces power demand for water distribution in a semi-arid basin

In the Brazilian semi-arid region, thousands of small dams have been built over time to enhance water availability, accumulating water and hydraulic energy at high altitudes. Simulations were performed in this study to assess how the arrangement of reservoirs impacts on the power demand for water distribution in the Banabuiú River Basin (19?800 km²), Brazil. The power required to pump water from 1405 reservoirs to all districts with diffuse demands is 6.5 GWh/year, whereas in the scenario with only the 12 larger strategic reservoirs, the power demand reached 45.3 GWh/year. Alone, the largest reservoir in the basin can supply water to all districts. Nonetheless, in that scenario, the power demand would reach 195 GWh/year, which is 30 times the power required in the real reservoir arrangement. Thus, decentralization by small reservoirs not only promotes more democratic access to water, but also increases energy efficiency by storing it at higher altitudes and closer to the diffuse demands.     

Land use change effects on runoff and erosion from plot to catchment scale on the basaltic plateau of Southern Brazil

In the region of the basaltic plateau in Southern Brazil, problems of runoff and erosion on the deep ferrallitic soils are becoming increasingly recognized. Land use change from conventional tillage using disk plough to no‐tillage on residues without terracing occurred at the beginning of the 1990s and it spread very quickly. Measurements of runoff and sediment concentrations on 1 m² plots receiving natural rainfall and simulated rainfall under different crops with different stages of growth and different tillage systems, field surveys and measurements of rills and gullies in nested experimental catchments indicate a relative decrease of runoff on slopes but an increase of subsurface flow, and a marked decrease of sheet and rill erosion and soil loss from plot to catchment scales. Nevertheless, the extension of parts of the gully system is still continuing, strongly influenced by extreme rainfall. Copyright © 1999 John Wiley & Sons, Ltd.     

On the feasibility of studying the exospheres of Earth-like exoplanets by Lyman-<Emphasis Type="Italic">α</Emphasis> monitoring

Observations of the Earth’s exosphere have unveiled an extended envelope of hydrogen reaching further than 10 Earth radii composed of atoms orbiting around the Earth. This large envelope increases significantly the opacity of the Earth to Lyman α (Lyα) photons coming from the Sun, to the point of making feasible the detection of the Earth’s transit signature from 1.35 pc if pointing with an 8 meter primary mirror space telescope through a clean line of sight (N _H <?10¹⁷ cm^??2), as we show. In this work, we evaluate the potential detectability of Earth analogs orbiting around nearby M-type stars by monitoring the variability of the Lyα flux variability. We show that, in spite of the interstellar, heliospheric and astrospheric absorption, the transit signature in M5 V type stars would be detectable with a dedicated Lyα flux monitor implemented in a 4–8 m class space telescope. Such monitoring programs would enable measuring the robustness of planetary atmospheres under heavy space weather conditions like those produced by M-type stars. A 2-m class telescope, such as the World Space Observatory, would suffice to detect an Earth-like planet orbiting around Proxima Centauri, if there was such a planet or nearby M5 type stars.     

Assessing rheological properties of fluid mud samples through tuning fork data

Ocean Dynamics - At the nautical bottom approach, part of the fluid mud layers can be included in the available depth if they present favorable rheology. As it is difficult to perform in situ...     

Correlated fast time structures at millimeter waves and hard X-rays during a solar burst

We present an analysis of the time profiles detected during a solar impulsive flare, observed at one-millimeter radio frequency (48 GHz) and in three hard X-ray energy bands (25–62, 62–111, and 111–325 keV) with high sensitivity and time resolution. The time profiles of all emissions exhibit fast time structures of 200–300 ms half power duration which appear in excess of a slower component varying on a typical time scale of 10 s. The amplitudes of both the slow and fast variations observed at 48 GHz are not proportional to those measured in the three hard X-ray energy bands. However, the fast time structures detected in both domains are well correlated and occur simultaneously within 64 ms, the time resolution of the hard X-ray data. In the context of a time-of-flight flare model, our results put strong constraints on the acceleration time scales of electrons to MeV energies.