Oil and the macroeconomy: a quantitative structural analysis

We consider an economy in which the oil costs, industrial production, and other macroeconomic variables fluctuate in response to fundamental domestic and external demand and supply shocks. We estimate the effects of these structural shocks on US monthly data for the 1973.1-2007.12 period using robust sign restrictions suggested by theory. The interplay between the oil market and the US economy goes in both directions. About 20% of changes in the cost of oil come in response to US aggregate demand shocks, while shocks originating in the oil market also affect the US economy, the impact depending on the nature of the shock: a negative oil supply shock reduces US output, whereas a positive oil demand shock has a positive and persistent effect on GDP.Business cycle; Oil prices; Structural VAR

A Differential Perspective on Gradient Flows on CAT(κ) -Spaces and Applications

We review the theory of Gradient Flows in the framework of convex and lower semicontinuous functionals on CAT(κ) -spaces and prove that they can be characterized by the same differential inclusion yt′∈-∂-E(yt) one uses in the smooth setting and more precisely that yt′ selects the element of minimal norm in - ∂-E(yt). This generalizes previous results in this direction where the energy was also assumed to be Lipschitz. We then apply such result to the Korevaar–Schoen energy functional on the space of L2 and CAT(0) valued maps: we define the Laplacian of such L2 map as the element of minimal norm in - ∂-E(u) , provided it is not empty. The theory of gradient flows ensures that the set of maps admitting a Laplacian is L2-dense. Basic properties of this Laplacian are then studied

Driver-pedestrian interaction under legal and illegal pedestrian crossings

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Stability of Sobolev inequalities on Riemannian manifolds with Ricci curvature lower bounds

We study the qualitative stability of two classes of Sobolev inequalities on Riemannian manifolds. In the case of positive Ricci curvature, we prove that an almost extremal function for the sharp Sobolev inequality is close to an extremal function of the round sphere. In the setting of non-negative Ricci curvature and Euclidean volume growth, we show an analogous result in comparison with the extremal functions in the Euclidean Sobolev inequality. As an application, we deduce a stability result for minimizing Yamabe metrics. The arguments rely on a generalized Lions' concentration compactness on varying spaces and on rigidity results of Sobolev inequalities on singular spaces.Comment: Revised version: moved some technical results to a new Appendix B, fixed Lemma 6.1, to appear in Adv. Mat

Maps of bounded variation from PI spaces to metric spaces

We study maps of bounded variation defined on a metric measure space and valued into a metric space. Assuming the source space to satisfy a doubling and Poincar\'e property, we produce a well-behaved relaxation theory via approximation by simple maps. Moreover, several equivalent characterizations are given, including a notion in weak duality with test plans.Comment: 38 page

Correlation of Ac-impedance and in situ X-ray spectra of LiCoO2

In-situ X-ray and AC-impedance spectra have been obtained simultaneously during the deintercalation of lithium from LiCoO2 using a specially designed electrochemical cell. The AC-dispersions have been correlated with the cell parameters obtained from the X-ray spectra. The correlation confirms previous hypothesis on the interpretation of the AC-dispersions in terms of an equivalent circuit comprising an element that relates the change of the intrinsic electronic conductivity, occurring at the early stages of deintercalation, to the semiconductor to metal transition caused by the change of the cell parameters

A lithium-ion battery based on LiFePO4 and silicon/reduced graphene oxide nanocomposite

In this paper, the preparation and chemical–physical characterization of a composite material made of silicon nanoparticles (nSi) and reduced graphene oxide (RGO) for using as an anode for lithium-ion batteries are report- ed. The nSi/RGO composite was synthesized by microwave irradiation followed by a thermal treatment under reducing atmosphere of a mixture of nSi and graphene oxide, and characterized by XRD, SEM, and TGA. The nano- structured material was used to prepare an electrode, and its electrochemical performance was evaluated in a lithium cell by galvanostatic cycles at various charge rates. The electrode was then coupled with a LiFePO4 cathode to fabricate a full lithium-ion battery cell and the cell performance evaluated as a function of the discharge rate and cycle number

Early-Stage Detection of Solid Oxide Cells Anode Degradation by Operando Impedance Analysis

Solid oxide cells represent one of the most efficient and promising electrochemical tech- nologies for hydrogen energy conversion. Understanding and monitoring degradation is essential for their full development and wide diffusion. Techniques based on electrochemical impedance spectroscopy and distribution of relaxation times of physicochemical processes occurring in solid oxide cells have attracted interest for the operando diagnosis of degradation. This research paper aims to validate the methodology developed by the authors in a previous paper, showing how such a diagnostic tool may be practically implemented. The validation methodology is based on applying an a priori known stress agent to a solid oxide cell operated in laboratory conditions and on the discrete measurement and deconvolution of electrochemical impedance spectra. Finally, experi- mental evidence obtained from a fully operando approach was counterchecked through ex-post material characterization