Fuzzy Inference System for VOLT/VAR control in distribution substations in isolated power systems

This paper presents a fuzzy inference system for voltage/reactive power control in distribution substations. The purpose is go forward to automation distribution and its implementation in isolated power systems where control capabilities are limited and it is common using the same applications as in continental power systems. This means that lot of functionalities do not apply and computational burden generates high response times. A fuzzy controller, with logic guidelines embedded based upon heuristic rules resulting from operators at dispatch control center past experience, has been designed. Working as an on-line tool, it has been tested under real conditions and it has managed the operation during a whole day in a distribution substation. Within the limits of control capabilities of the system, the controller maintained successfully an acceptable voltage profile, power factor values over 0,98 and it has ostensibly improved the performance given by an optimal power flow based automation system

Stochastic theory of lineshape broadening in quasielastic He atom scattering with interacting adsorbates

The activated surface diffusion of interacting adsorbates is described in terms of the so-called interacting single adsorbate approximation, which is applied to the diffusion of Na atoms on Cu(001) for coverages up to 20% in quasielastic He atom scattering experiments. This approximation essentially consists of solving the standard Langevin equation with two noise sources and frictions: a Gaussian white noise accounting for the friction with the substrate, and a white shot noise characterized by a collisional friction simulating the adsorbate-adsorbate collisions. The broadenings undergone by the quasielastic peak are found to be in very good agreement with the experimental data reported at two surface temperatures 200 and 300 K.Comment: 6 pages, 3 figure

Life cycle assessment of hot mix asphalt with recycled concrete aggregates for road pavements construction

In this study a comparative life cycle assessment (LCA) was conducted according to a ‘cradle-to-laid’ approach to evaluate the potential environmental impacts related to the use of recycled concrete aggregates (RCAs) as a partial replacement of coarse natural aggregates in the production of Hot Mix Asphalt (HMA). Specifically, three percentages of RCA replacements were analyzed: 15, 30 and 45%. Primary data collected mainly through surveys performed in Colombian contractors from the region of Barranquila were used to model the foreground system. The SimaPro 8.4.0 software was used for modelling the processes analyzed in the case study and all the life cycle inputs and outputs related to the functional unit were characterised during life cycle impact assessment (LCIA) phase into potential impacts according to the TRACI v.2.1 impact assessment methodology. The results of the case study showed that the mixtures incorporating 15 and 30% of RCA can be considered as eco-friendly alternatives to the conventional mixture (i.e. no RCA content), as both allow reductions in all impact categories scores. On the contrary, the mixture that contains 45% of RCA denoted a lower environmental performance than that of the conventional mixture

A generalized Chudley-Elliott vibration-jump model in activated atom surface diffusion

Here the authors provide a generalized Chudley-Elliott expression for activated atom surface diffusion which takes into account the coupling between both low-frequency vibrational motion (namely, the frustrated translational modes) and diffusion. This expression is derived within the Gaussian approximation framework for the intermediate scattering function at low coverage. Moreover, inelastic contributions (arising from creation and annihilation processes) to the full width at half maximum of the quasi-elastic peak are also obtained.Comment: (5 pages, 2 figures; revised version

Impacto del cambio climático sobre la distribución de Prosopis Hassleri y P.alba en la región chaqueña

El algarrobo, principalmente Prosopis alba y P. hassleri son las especies nativas de mayor uso para madera de aserrío en nuestro país, registrándose en los últimos años un aumento constante en la tasa de consumo. Dado que la totalidad de la madera de algarrobo consumida proviene de bosques nativos, la explotación del recurso es insostenible no sólo desde el punto de vista ambiental sino también económico. A esta situación crítica se le agregan además problemáticas que están afectando a los bosques a escala global como es la expansión de la frontera agrícola sobre áreas de bosque nativo, forestación con especies exóticas de crecimiento rápido, y la interacción de estos factores con el cambio climático actual. En este trabajo indagamos sobre el posible impacto del cambio climático sobre la distribución de P. hassleri (Algarrobo paraguayo) y de tres morfotipos de P. alba (santiagueño, chaqueño y chaqueño sur) en el norte de Argentina, para proveer información útil en la planificación de estrategias de conservación y manejo de los recursos genéticos nativos. Para ello, se utilizaron modelos predictivos de nicho que permitieron estimar la distribución potencial de ambas especies bajo un escenario actual y de cambio climático futuro. De esta manera se pudieron establecer áreas de alto y bajo impacto, y nuevas áreas adecuadas para la persistencia de las respectivas especies. Se utilizaron datos georreferenciados de 30-77 individuos de poblaciones naturales de cada una de las especies y morfotipos, y los 19 parámetros bioclimáticos disponibles en la base de datos mundial WorldClim. Los análisis de modelado de nicho actual y futuro se realizaron mediante el algoritmo de máxima entropía implementado en el programa Maxent; posteriormente los modelados resultantes fueron procesados en el programa DIVA-GIS. Los resultados indican que todas las especies/morfotipos tienden a desplazar su área de distribución hacia el sur, excepto el morfotipo P. alba chaqueño sur que se expandiría hacia el norte. Prosopis hassleri sería la especie que perdería la mayor proporción de superficie de su distribución actual. Sin embargo, en un escenario futuro surgirían áreas favorables para su persistencia cuya superficie duplicaría la distribución actual. Contrariamente, el morfotipo santiagueño de P. alba conservaría casi la totalidad de su área de distribución actual, y es la que menos ampliaría su rango de distribución en un escenario futuro. A partir de los resultados obtenidos se sugieren estrategias de manejo y conservación para estas especies, a través de la identificación y protección de refugios climáticos y del establecimiento de corredores biológicos que favorezcan la dispersión natural de las especies hacia nuevas áreas adecuadas. (Nuestro agradecimiento al Proyecto Específico INTA PNFOR044341 y al Banco Nacional de Germoplasma de Prosopis, FCA-UNC, por facilitar la información básica para este trabajo).Fil: Venier, Maria Paula. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cosacov Martinez, Andrea. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: López Lauenstein, D.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; ArgentinaFil: Vega, C.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; ArgentinaFil: Verga, A.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias; Argentin

Linear response theory of activated surface diffusion with interacting adsorbates

Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(001) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.Comment: 40 pages, 4 figure

Synthesis, characterization, and electrocatalytic ability of γ-Fe2O3 nanoparticles for sensing acetaminophen

Maghemite (γ-Fe2O3) nanoparticles have been synthesized using co-precipitation method followed by chemically induced transition process. As prepared nanoparticles have been analyzed by X-ray diffraction, Raman and FTIR spectroscopies which reveal the γ-Fe2O3 phase. These γ-Fe2O3 nanoparticles have been used to modify the glassy carbon electrode (GCE) to form nano γ-Fe2O3 modified GC electrode for electrochemical sensing of acetaminophen (C6H9NO2) using potential controlled cyclic voltammetric (CV) technique. The obtained modified electrode shows an excellent electrocatalytic ability to sense acetaminophen in 0.1 M KCl supporting electrolyte. In addition, a significant enhancement in anodic peak current has been observed using nano γ-Fe2O3 modified GC electrode than the bare electrode. The CV plots reveal that redox peaks have been linearly co-related to the acetaminophen concentration in the range of 0.031 mM to 1 mM with sensitivity ~30.78 µA/mM

NaI(Tl) Scintillator's Response Functions for Point-like and Distributed Gamma-ray Sources

The response functions of a NaI(Tl) detectors have been estimated using Monte Carlo methods. Response functions were calculated for monoenergetic photon sources (0.05 to 3 MeV). Responses were calculated for point-like sources and for sources distributed in Portland cement cylinders. Calculated responses were used to estimate the detector efficiency for point-like and distributed sources. Samples of cylindrical Portland cement were prepared and exposed to the photoneutron field produced by a 15 MV linac used for radiotherapy. Short half-life radioisotopes were induced and the activity was determined by measuring the pulse-height spectra with a NaI(Tl) g-ray spectrometer that was calibrated using point-like sources. Instead of doing corrections due to differences between the geometry, material and solid angle of point-like sources used for calibration, and the Portland cement cylinders, the detection efficiency was determined using the ratio between the efficiencies for the point-like and the distributed sources estimated with the Monte Carlo calculations, and the activity of the induced isotopes in cement was obtained