Effect of Different Nucleating Agents on the Crystallization of Ziegler-Natta Isotactic Polypropylene

Ziegler-Natta isotactic polypropylene (iPP) was melt mixed with four different nucleating agents (carbon nanotubes (CNT), carbon nanofibers (CNF), lithium benzoate (LiBe), and a sorbitol derivative (Millad)) in order to study their effect on the crystallization of iPP. It was found that the four different nucleating agents promote the alpha crystalline form. At 0.01 wt%, the carbon nanoparticles produced the higher crystallization temperature “Tc” (~119°C), whereas, at 0.10 wt%, LiBe and Millad produced a markedly higher Tc (~125°C). Tc of pure iPP was 111°C. With 0.1 wt% nucleating agent, at 120°C, the crystallization half-life time of PP, when using LiBe or Millad, was 15 times faster than for pure PP, whereas, when using carbon nanoparticles, it was 20–25 times faster. At 135°C, with 0.01 wt% nucleating agent, the isothermal crystallization process of iPP was completed after 25 min, as well as with Millad. With LiBe, it was completed after just 15 min and, with any of the carbon nanoparticles, it was practically over after only a couple of minutes

Proyecto Saucay II. Presa de Chanlud

El proyecto Saucay II comprende la presa de Chanlud memorias de justificación y descripción, características generales condiciones geológicas, verificación, estructural. El capítulo II organización del campamento, aprovisionamiento de materiales, hormigón armado. El capítulo III cálculos estructurales, el análisis de la presa por el método de los elementos finitos, capítulo IV cálculos hidráulico y del túnel de aducción, cálculo de organización del campamento como productividad de la torre grúa, silos, energía eléctrica, volúmenes de las excavaciones, perforaciones, presupuesto y costo estimativoIngeniero CivilCuenc

Forests and water in South America

South America is experiencing rapid change in forest cover, of both native and planted forest. Forest cover loss is primarily attributable to fire, logging, and conversion of native forest to agriculture, pasture, and forest plantations, and types of change vary within and among the many diverse types of forests in South America. Major changes in forest cover and growing policy concerns underscore an urgent need for research on sustainable forest management and water ecosystem services in South America. Differences in land ownership and management objectives create trade-offs between wood production and water ecosystem services from forests. Work is needed to quantify how forest change and management affect ecosystem services, such as wood production versus water provision. Current scientific understanding of forest management effects on water ecosystem services in South America has important limitations, including a scarcity of long-term records and few long-term integrated watershed studies. Industry, government, universities, and local communities should collaborate on integrated applied studies of forests and water. Data archiving and publically available data are required. The creation of national networks and a multi-country South America network to identify and implement common water research protocols, share results, and explore their implications would promote common and well-supported policies. Hydrologists working in South America are well placed to tackle the challenges and opportunities for collaborative research that will maintain the intrinsic values and water ecosystem services provided by South America's forests

Analysis of the drought recovery of Andosols on southern Ecuadorian Andean páramos

The Neotropical Andean grasslands above 3500ma.s.l., known as páramo, offer remarkable ecological services for the Andean region. The most important of these is the water supply of excellent quality to many cities and villages in the inter-Andean valleys and along the coast. The páramo ecosystem and especially its soils are under constant and increased threat by human activities and climate change. In this study, the recovery speed of the páramo soils after drought periods are analysed. The observation period includes the droughts of 2009, 2010, 2011, and 2012 together with intermediate wet periods. Two experimental catchments-one with and one without páramo-were investigated. The Probability Distributed Moisture (PDM) model was calibrated and validated in both catchments. Drought periods and its characteristics were identified and quantified by a threshold level approach and complemented by means of a drought propagation analysis. At the plot scale in the páramo region, the soil water content measured by time domain reflectometry (TDR) probes dropped from a normal value of about 0.84 to ?0.60 cm3 cm-3, while the recovery time was 2-3 months. This did not occur at lower altitudes (Cumbe) where the soils are mineral. Although the soil moisture depletion observed in these soils was similar to that of the Andosols (27 %), decreasing from a normal value of about 0.54 to ?0.39 cm3 cm-3, the recovery was much slower and took about 8 months for the drought in 2010. At the catchment scale, however, the soil water storage simulated by the PDM model and the drought analysis was not as pronounced. Soil moisture droughts occurred mainly in the dry season in both catchments. The deficit for all cases is small and progressively reduced during the wet season. Vegetation stress periods correspond mainly to the months of September, October and November, which coincides with the dry season. The maximum number of consecutive dry days were reached during the drought of 2009 and 2010 (19 and 22 days), which can be considered to be a long period in the páramo. The main factor in the hydrological response of these experimental catchments is the precipitation relative to the potential evapotranspiration. As the soils never became extremely dry nor close to the wilting point, the soil water storage capacity had a secondary influence

Integrating hydraulic, physicochemical and ecological models to assess the effectiveness of water quality management strategies for the River Cuenca in Ecuador

During the past decades, the development and use of ecological models to predict the presence or absence of macroinvertebrates as water quality indicators for decision support in river management has gained a lot of interest. However, these models rarely integrate hydromorphological, physicochemical, and biological components in the submodels. We developed a generic framework for decision support in water management that can be applied to any river basin based on an integrated modelling approach. This approach integrates a mechanistic hydraulic and physicochemical water quality model with aquatic ecological models. Two types of ecological models were developed, habitat suitability models to predict the occurrence of macroinvertebrates and ecological assessment models to predict a biotic index score. Our main purpose was to assess the effectiveness of different wastewater treatment/disposal strategies considering receiving water's ecological aspects and to determine water quality requirements. This paper presents the testing and validation of this integrated framework on a case study of a mountain river (River Cuenca) in the Andes of Ecuador. Three wastewater management scenarios were tested. The different scenarios indicated that the foreseen investments in sanitation infrastructure will lead to modest improvements of the ecological water quality. This improvement (i.e. increase of the biotic index) was only identified in 6 of the 21 monitoring stations considered in the River Cuenca and its tributaries. Therefore, it is necessary to control the impact of the industrial wastewaters discharges and the diffuse pollution at the upper catchment of the tributaries to achieve a good ecological status. With these results, we proved that integrated models, like the one presented here, have an added value for decision support in water management by coupling ecological water quality to a set of hydraulic and chemical water quality measures based on a water quality model. In order to improve these models, it is necessary to change the river monitoring strategy towards collection of data which include simultaneous measurements of physicochemical, hydromorphological and biological data. © 2013 Elsevier B.V

Study for Selecting the Solution of a Dam's Discharge Chute Canal

Some hydraulic studies to find an adequate solution for a discharge chute canal are presented in this paper. Tha chute canal is appropriate work of the Lechugal 2 earth dam (H=20 m), which is part of a large irrigation system from Ecuador, presently under construction. Studies have consisted in experiments on hydraulic model of the chute canal built at geometrical scale 1:35 and by numerical simulations in one-dimensional steady flow running HecRas software. In first stage numerical model was calibrated based on experiment results and in second stage other three constructive variants of the chute canal were analysed numerically in order to improve the solution settled by hydraulic model. The technical performances of each variant settled by these experimental and numerical studies follow to be completed with economical analyses which will allow designer to choose the best solution for discharge chute canal.Buchares

Estudio y selección de una arquitectura orientada a servicios (SOA) que permita la integración de sistemas informáticos legados

El presente trabajo, tiene por objeto el analisis del marco tecnologico relacionado con la integracion de sistemas informaticos legados, ademas de esto, se revisaran algunas tecnicas para la exposicion de servicios, esto con objetivo de establecer una arquitectura orientada a servicios que puede ser implementada en el Programa para el Manejo del Agua y Suelo (Promas), y que pueda permitir la integracion a la misma de varios sistemas informaticos que han sido creados y que se encuentran todavıa en funcionamiento. Para poder cumplir este objetivo, es necesario el anali- sis de los principales sistemas informaticos para poder extraer las caracteristicas principales y agruparlos de acuerdo a estas, una vez realizada esta agrupacion es necesario tambien el analisis de algunas de las tecnicas que existen actualmente para poder llevar a cabo esta integracion. Una vez identificadas estas tecnicas,es necesario tambien el establecimiento de una metodologia a seguir para la exposicion de futuros servicios, para esto se ha visto necesario la implementacion de una arquitectura piloto que sea capaz de soportar algunos de los servicios que son considerados como vitales en las actividades diarias del Programa. Al final de la implementacion del mencionado piloto, se podra disponer de una arquitectura orientada a servicios que sea capaz de incluir nuevos requerimientos y adaptarse facilmente a los cambios tecnologicos que puedan presentarse.status: publishe