13,061 research outputs found
Mulching and soil tillage influence on the thermal behaviour of a Luvisol surface layer
Important energy exchanges at soil surface regulate the thermal environment within top soil layer and the boundary layer above it. By this reason, the application of mulches or the modelling of micro relief by soil tillage are common practises to modify the thermal regime of a soil. The aim of this study is to compare the effect on thermal behaviour of a Luvisol resulting of soil tillage and the application of stubble mulch and, different amounts of straw mulch. For this purpose, experiments were performed from January to May 2007 in a field sowed with winter wheat. Temperatures were measured with copper-constantan (Type T) thermocouples placed over straw and over stubble, at soil surface and at 2, 4 and 8 cm depth. Temperatures above canopy were also recorded.
Daily mean temperatures and thermal amplitudes in the top soil layer covered by straw mulch were smaller than those verified either by stubble mulch or with soil tillage. Daily minimum temperatures in mobilized plots or covered by stubble mulch were smaller than those verified in plots covered by straw mulch, therefore being the former treatments more susceptible to frost than the later ones. Thermal differences between the four plots decreased significantly with wheat growth. Implications of these techniques of soil temperature control for crop growth are also discussed
Mulching and soil tillage influence on the thermal behaviour of a Luvisol surfacel layer
Important energy exchanges at soil surface
regulate the thermal environment within top soil layer and
the boundary layer above it. By this reason, the application
of mulches or the modelling of micro relief by soil tillage are
common practises to modify the thermal regime of a soil.
The aim of this study is to compare the effect on thermal
behaviour of a Luvisol resulting of soil tillage and the
application of stubble mulch and, different amounts of straw
mulch. For this purpose, experiments were performed from
January to May 2007 in a field sowed with winter wheat.
Temperatures were measured with copper-constantan (Type
T) thermocouples placed over straw and over stubble, at soil
surface and at 2, 4 and 8 cm depth. Temperatures above
canopy were also recorded.
Daily mean temperatures and temperature amplitudes
in the top soil layer covered by straw mulch were smaller
than those verified either by stubble mulch or with soil
tillage. Daily minimum temperatures in mobilized plots or
covered by stubble mulch were smaller than those verified in
plots covered by straw mulch, therefore being the former
treatments more susceptible to frost than the later ones.
Thermal differences between the four plots decreased
significantly with wheat growth. Implications of these
techniques of soil temperature control for crop growth are
also discussed
A Stock and FlowConsistent Post Keynesian Model for an Open Economy with ImportedIntermediary Inputs and Ex-Ante Portfolio Allocation
Unscented Bayesian Optimization for Safe Robot Grasping
We address the robot grasp optimization problem of unknown objects
considering uncertainty in the input space. Grasping unknown objects can be
achieved by using a trial and error exploration strategy. Bayesian optimization
is a sample efficient optimization algorithm that is especially suitable for
this setups as it actively reduces the number of trials for learning about the
function to optimize. In fact, this active object exploration is the same
strategy that infants do to learn optimal grasps. One problem that arises while
learning grasping policies is that some configurations of grasp parameters may
be very sensitive to error in the relative pose between the object and robot
end-effector. We call these configurations unsafe because small errors during
grasp execution may turn good grasps into bad grasps. Therefore, to reduce the
risk of grasp failure, grasps should be planned in safe areas. We propose a new
algorithm, Unscented Bayesian optimization that is able to perform sample
efficient optimization while taking into consideration input noise to find safe
optima. The contribution of Unscented Bayesian optimization is twofold as if
provides a new decision process that drives exploration to safe regions and a
new selection procedure that chooses the optimal in terms of its safety without
extra analysis or computational cost. Both contributions are rooted on the
strong theory behind the unscented transformation, a popular nonlinear
approximation method. We show its advantages with respect to the classical
Bayesian optimization both in synthetic problems and in realistic robot grasp
simulations. The results highlights that our method achieves optimal and robust
grasping policies after few trials while the selected grasps remain in safe
regions.Comment: conference pape
Accessibility dynamics and regional cross-border cooperation (CBC) perspectives in the portuguese—spanish borderland
Accessibility plays a major role in achieving sustainable transport, and therefore urban
and regional sustainability. The urban public transport system promotes mobility and realizes a
large part of urban movements. Moreover, improving accessibility in order to promote sustainable
transport requires the application of new concepts and indicators as a powerful tool in the process of
creating a balanced urban transport system. In this regard, one of the main goals of this research
is to present an overview of the relevant accessibility indicators and assessment of accessibility in
regional Cross-Border Cooperation (CBC) in order to transcendence challenges and obstacles for
sustainable transportation in these regions along of Portuguese-Spanish border. This paper focuses
on the accessibility of cross-border cooperation scenarios along the border regions of Alto Alentejo
(Portugal) and Badajoz (Spain) where the Case Study Research Method (CSR) made it possible to
recognize accessibility as a key factor in territorial success. Also, accessibility analysis can assess
improvements as well as regional imbalances. In addition, this methodology can be used to identify
missing links, which requires new investments enabling long-term sustainability.info:eu-repo/semantics/publishedVersio
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