3,686 research outputs found
A semilinear problem with a W^{1,1}_0 solution
We study a degenerate elliptic equation, proving the existence of a W^{1,1}_0
distributional solution
The taxation of motor fuel : international comparison
This paper assesses whether the level of taxation of motor fuel is broadly appropriate in a group of countries (OECD, BRICs and South Africa) accounting for more than 80 percent of world greenhouse gas emissions. The analysis deals with emissions from oil combustion in transport, which account for about 40 percent of carbon dioxide emissions. In the benchmark specification, six countries (responsible, in turn, for more than 40 percent of worldwide motor-fuel greenhouse gas world emissions) would be undertaxing motor fuel. The authors evaluate the sensitivity of the results to the values of the elasticities and externalities that used in the analysis. They find that varying the values of these parameters (within the level of uncertainty reasonably associated with them) significantly affects the results. This implies that, while informative, the results must be taken as indicative. Further analysis for a particular country must rely on a well-informed choice for the values of the country-specific parameters.Transport Economics Policy&Planning,Energy Production and Transportation,Taxation&Subsidies,Climate Change Mitigation and Green House Gases,Climate Change Economics
Existence results for a Cauchy-Dirichlet parabolic problem with a repulsive gradient term
We study the existence of solutions of a nonlinear parabolic problem of
Cauchy-Dirichlet type having a lower order term which depends on the gradient.
The model we have in mind is the following: \begin{cases}\begin{split} &
u_t-\text{div}(A(t,x)\nabla u|\nabla u|^{p-2})=\gamma |\nabla u|^q+f(t,x)
&\qquad\text{in } Q_T,\\ & u=0 &\qquad\text{on }(0,T)\times \partial \Omega,\\
& u(0,x)=u_0(x) &\qquad\text{in } \Omega, \end{split}\end{cases} where
, is a bounded domain of , , , the matrix is coercive and with measurable bounded
coefficients, the r.h.s. growth rate satisfies the superlinearity condition and the initial
datum is an unbounded function belonging to a suitable Lebesgue space
. We point out that, once we have fixed , there exists a
link between this growth rate and exponent which allows
one to have (or not) an existence result. Moreover, the value of deeply
influences the notion of solution we can ask for. The sublinear growth case
with is dealt at the end of the paper for what concerns
small value of , namely
The role of interplay between coefficients in the -convergence of some elliptic equations
We study the behavior of the solutions of the linear Dirichlet problems
with respect to perturbations
of the matrix (with respect to the -convergence) and with respect to
perturbations of the nonnegative coefficient and of the right hand side
satisfying the condition
Existence and multiplicity for elliptic problems with quadratic growth in the gradient
We show that a class of divergence-form elliptic problems with quadratic
growth in the gradient and non-coercive zero order terms are solvable, under
essentially optimal hypotheses on the coefficients in the equation. In
addition, we prove that the solutions are in general not unique. The case where
the zero order term has the opposite sign was already intensively studied and
the uniqueness is the rule.Comment: To appear in Comm. PD
Diffeomorphism-invariant properties for quasi-linear elliptic operators
For quasi-linear elliptic equations we detect relevant properties which
remain invariant under the action of a suitable class of diffeomorphisms. This
yields a connection between existence theories for equations with degenerate
and non-degenerate coerciveness.Comment: 16 page
Innovative and classical field-based approach for analogue reservoir modelling: the Precipice Sandstone, Qld
The Jurassic Precipice Sandstone was studied as a potential oil and gas reservoir
unit within the Surat Basin, Queensland. Since the early depletion of its
productive fields, the Precipice Sandstone has been recently selected by the
ANLECR&D Company as the target unit for the injection of up to 200.000 tons of
Greenhouse Gas Stream derived from coal-fired power stations.
The aim of this work is to provide new outcrop-based depositional models for the
so called Lower and Upper Precipice Sandstone, with their first application in
reservoir characterization.
Trough a classical facies analysis approach, both at the outcrop scale and borehole
core-cuts, and the innovative use of 3D Digital Photogrammetry, this study assists
the creation of the most reliable geo-cellular reservoir model.
The Lower Precipice outcrop studied at Nathan Gorge National Park shows unitbar
and compound-bar deposits typical of the alluvial architecture of a sandybraided
river system. On the other hand, the Upper Precipice shows lobated
bodies comparable to mouth-bar deposits which might be ascribed to a shallowwater
delta complex. The recognition of braided-bar deposits in the studied
outcrops deals with the well-known fluvial origin the Lower Precipice. However,
despite the common thought of the pure fluvial nature of the Precipice Sandstone,
the Upper Precipice outcrops might provide new insights on the interpretations of
the depositional environment of this unit.
In this framework, the presented detailed facies analysis study, enhanced by the
powerful 3D Digital Photogrammetric technique, demonstrates that sedimentary
investigations on the Precipice Sandstone reservoir analogue reduces uncertainties
in the reservoir characterization and supports the creation of a 3D reservoir model.
Nevertheless, the advancement of knowledge of the Upper Precipice depositional
environment might have further implications in the understanding of geological
evolution of the Jurassic-Cretaceous Surat Basin.ope
Computational Investigation of Nanoparticles at the Biointerface
Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions which are able to provide solutions to both theoretical and practical problems in areas such as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles (AuNPs) with core diameters in the rage 1 1210 nm have emerged as a powerful class of materials for a variety of biomedical applications. The utility of AuNPs is enhanced by our ability in tuning their surface properties by grafting multiple ligand species able to self-assemble in mixed-monolayers. Thus, identification of molecular designing rules is essential to achieve a precise control of specifically patterned monolayer protected nanoparticles for an intended biological outcome. In this thesis are described the evidences of our investigation of the self-organization of different mixtures of immiscible ligands on a spherical gold surface. The evaluation of the role of some critical parameter such as core dimension, different chemistry and relative ligand length and ratio as well as solvent was the starting point to develop a standard procedure to tune the self-assembled monolayer (SAM) morphology. Studies of the morphology of these mixed monolayers were carried out using an in-silico approach based on multiscale molecular simulations. Then, combining theory and experiments, we investigated the role of ligand arrangement and composition on the interaction with model lipid bilayer (either simple and complex) and with cells of these monolayer protected NPs. In-silico models were then employed to study the binding of patterned AuNps with human serum albumin (HSA), uncovering the impact of the monolayer morphologies on protein-NP interfaces. Laslty, a third kind of biointerface was taken into account and the supramolecular binding of small molecules, toward mixed/homoligand shells was disclosed
new perspectives in emergency mapping
AbstractIn recent years, growing attention is paid to remote sensing when used for disaster management applications. This is essentially due to the large variety of remotely acquired imagery availa..
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