Análisis, diseño y construcción de un sistema de carga sustentable

Se presenta el diseño y construcción de un circuito electrónico de carga de batería de celulares/tablets hasta 2A. Consta de un conversor OC-OC buck y display LCO, así como un diseño propietario de un freno electrodinámico para ser colocado en una bicicleta fija de diseño propio.Área: Ingeniería, Arquitectura y Tecnología

Can supply chain's coordination mechanisms include small holders? Insight from an empirical work in Costa Rica.

Small holders' agriculture is currently facing new stakes due to State's withdrawal from agricultural support and to higher market requests for producing agricultural products. Different coordination mechanisms can be observed inside the supply chains involving farmers, farmers' organizations, and others stakeholders. They depend on the nature of the product, the characteristics of the stakeholders involved, the technical specifications related to the transactions, and the institutional environment. Relying on a comparative case study methodology, the paper analyzes the consequences of different coordination mechanisms on inclusion or exclusion of small farmers in the northern region of Costa Rica. Market coordination could be an efficient way to integrate farmers in supply chains in the case of low technical specifications and of existence of adequate selling mechanisms. Hybrid coordination is the main mechanism and facilitates the inclusion of small farmers, depending on the farmers' organizations capacities to negotiate adequate rules. In some situations hybrid coordination with captive relationships could occur but leads to a more or less rapid exclusion process.supply chain, small holders, farmers, contracting, coordination, Costa Rica, Agribusiness,

Pago por servicios ambientales en Guatemala: un inventario preliminar de experiencias : Informe de mision en Guatemala 27-29 de febrero 2012

Rapport

Trajectories of vector fields asymptotic to formal invariant curves

We prove that a formal curve $\Gamma$ that is invariant by a $C^\infty$ vector field $\xi$ of $\mathbb{R}^m$ has a geometrical realization, as soon as the Taylor expansion of $\xi$ is not identically zero along $\Gamma$. This means that there is a trajectory $\gamma$ of $\xi$ which is asymptotic to $\Gamma$. This result solves a natural question proposed by Bonckaert nearly forty years ago. We also construct an invariant $C^0$ manifold $S$ in some open horn around $\Gamma$ which is composed entirely of trajectories asymptotic to $\Gamma$, and contains the germ of any such trajectory. If $\xi$ is analytic, we prove that there exists a trajectory asymptotic to $\Gamma$ which is, moreover, non-oscillating with respect to subanalytic sets

Emissions from pre-Hispanic metallurgy in the South American atmosphere

Peer reviewedPublisher PD

O método do Lagrangeano aumentado no estudo de cabos umbilicais

O objetivo deste trabalho é apresentar um modelo numérico para cabos umbilicais hiperelásticos que experimentem grandes deslocamentos e grandes rotacoes. O modelo mecanico resulta num sistema náo-linear, que é resolvido por um método de decomposicáo-coordenacao via Lagrangeano Aumentado. Este tratamento posibilita a descricáo do acoplamento existente entre flexao e torcáo em cabos submetidos A grandes delocamentosPeer Reviewe