Design of a Trans-Horizon radio link for ultra high and super high frequencies

Cost considerations and availability of frequencies condition the feasibility of links at distances in which there is no line of sight between antennas. These trans-horizon links require precise design procedures to determine whether the intensity of the signal and its noise ratio allow reception with reasonable quality. The present work describes a procedure for radio electric link calculation to transmit voice and data signals through bandwidth at ultra high and super high frequencies.Presentado en el V Workshop Arquitectura, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

Design of a Trans-Horizon radio link for ultra high and super high frequencies

Cost considerations and availability of frequencies condition the feasibility of links at distances in which there is no line of sight between antennas. These trans-horizon links require precise design procedures to determine whether the intensity of the signal and its noise ratio allow reception with reasonable quality. The present work describes a procedure for radio electric link calculation to transmit voice and data signals through bandwidth at ultra high and super high frequencies.Presentado en el V Workshop Arquitectura, Redes y Sistemas Operativos (WARSO)Red de Universidades con Carreras en Informática (RedUNCI

Cambio tecnológico y eficiencia técnica en predios lecheros de tres países del cono sur.

The progressive liberalization of agricultural markets, along with the threat that imported products can pose to local producers, reveals the importance of productivity growth as a mechanism to improve competitiveness. Technical efficiency measurement is the most studied component of productivity because it can help to generate valuable information for policy formulation and farm level decisions focused on the improvement of farm performance. This study uses unbalanced panel data sets for dairy farms from Argentina, Chile and Uruguay, to estimate stochastic production frontier models. These frontiers are then used to estimate economies of size, technological change and technical efficiency. All estimations are based on the Battese and Coelli (1992) model, which is widely used in empirical productivity studies. The models for all three countries exhibit increasing returns to scale, which suggests that the dairy farms in the samples are operating at a sub-optimal size. The average annual rate of technological change for Argentina was 0.9%, for Chile 2.6% and for Uruguay 6.9%, while average technical efficiency was 87.0%, 84.9% and 81.1%, respectively.La liberalización progresiva de los mercados agrícolas, junto a la amenaza que implica para productores nacionales la competencia de productos importados, dejan en claro la relevancia del incremento en la productividad como un elemento para mejorar la competitividad. La medición de la eficiencia técnica es uno de los componentes de la productividad más estudiados, debido a que proporciona información valiosa al momento de formular políticas y tomar decisiones destinadas a mejorar la administración predial. Este trabajo utiliza datos de panel desbalanceados de predios lecheros provenientes de Argentina, Chile y Uruguay, para estimar fronteras estocásticas de producción. Luego estas fronteras se usaron para analizar economías de tamaño, tasas de cambio tecnológico y eficiencia técnica. En todas las estimaciones se empleó el modelo de Battese y Coelli (1992), ampliamente usado en la literatura de productividad. Los modelos para los tres países exhiben economías de escala crecientes, lo que implica que los predios en las muestras operan a un tamaño sub-óptimo. La tasa promedio anual de cambio tecnológico fue 0,9% para Argentina, 2,6% para Chile y 6,9% para Uruguay mientras que la eficiencia técnica media fue igual a 87,0%, 84,9% y 81,1%, respectivamente

Efficiency Measures in the Agricultural Sector: The Beginning

agricultural productivity is often based on non-parametric models (DEA), or stochastic models (SFA). In this initial article, the editors start by pointing that the models (DEA and SFA) allow estimating the efficiency of the production frontier and their structural forms. Then, it is presented, in general terms, the differences between DEA and SFA models: DEA model involves the use of technical linear programming to construct a non-parametric piecewise surface, and SFA models comprise econometric models with a random variable, or an error term, including two components: one to account for random effects and another to take care of the technical inefficiency effects. Finally, it shows a comparison between the two approaches (SFA and DEA) and the advantages and disadvantages of their utilizations