Publicaciones Científicas

La Región del Biobío en el centro sur de Chile es una zona de transición climática donde conviven bosques templados y esclerófilos, generando una zona de alta diversidad. Sin embargo, el área ha sido fuertemente afectada por la intervención antrópica y solo quedan algunos relictos de matorral y bosque nativo. Los geométridos, al igual que muchos insectos, están estrechamente asociados a la vegetación y por lo tanto serán afectados directamente por la intervención que se efectúe sobre esta. Así, en este estudio evaluamos los patrones de distribución y diversidad de geométridos en la Región del Biobío, con el objetivo de proponer sitios de alta prioridad para conservación mediante la identificación de áreas de endemismo y hot spots de diversidad. Los datos disponibles fueron procesados mediante análisis de parsimonia de endemismo y análisis de complementariedad, apoyados por SIG para rellenar vacíos y extrapolar la distribución de algunas especies de acuerdo a criterios establecidos. Encontramos una diversidad de 120 especies de geométridos, que corresponden a un 37.5 % de la diversidad nacional, distribuidas en seis áreas de endemismo, localizadas en las formaciones vegetacionales más frecuentes en la Región del Biobío: bosque alto-montano de Nahuelbuta, bosque esclerófilo de los arenales, bosque caducifolio de Concepción, bosque caducifolio andino del Biobío y bosque caducifolio de la frontera. El análisis de complementariedad determinó que 18 celdas contienen el número total de especies en la región. Basado en los análisis anteriores, se determinó que hay cinco áreas que deben ser consideradas como sitios de alta prioridad para la conservación de geométridos: (1) la ladera occidental de la Cordillera de Nahuelbuta y sector costero adyacente, (2) el área Pencopolitana de la zona litoral de la región, (3) Cerro Negro-Quillón, (4) Las Trancas, y (5) la zona del valle del Queuco-Alto Biobío.

The Bío Bío River is the second largest river in Chile considering both discharge and length. The Bío Bío River flows through the second most important economical centre in Chile and it has been recently classified as one of the world's largest river systems strongly affected by fragmentation and change in flow regime, mainly due to hydropower and irrigation. The cities of Hualqui, Chiguayante, Concepción, Hualpén, and San Pedro de la Paz are located along the last 25 km of its course, and are exposed to a high flood risk due to a combination of increasing rainfall storms and the dams operation located in the upper basin. This work assessed several structural and non-structural flood defence alternatives for the lower 25 km of the river. A one-dimensional (1D) hydraulic model was used under different discharge scenarios. The results showed that storage areas and diversion canals located along the lower part of the Bío Bío River did not prove to be a suitable solution. Nevertheless, it was found that the most effective alternative implies a reservoir operation focused on storing the extra water produced by the incoming flood. Conclusions support the materialization of reservoir emergency operation protocols, as indicated in the Reglamento de Ley N°20.304, approved by Decreto de Ley 138, Chile.

The hydrology of scarce-data areas, such as the mountainous area of the Andes, is poorly known mainly owing to the lack of data. Global gridded climatological datasets (GGCDs) are becoming more precise and common, but the utility of these datasets and their applicability to complex hydrological systems are still not yet well determined. In this paper the reliability of a GGCD is evaluated as an alternative source to supply the lacking in situ observations, with the aim of studying the hydrology of a mountainous area in south-central Chile. The GGCDs are found to recover the climate variability in Andean areas, and partially recover the orographic effect caused by the mountains. A finding of practical relevance is that GGCDs could be considered as an adequate source for performing hydrological models and studies under high spatial variability and scarce-data environments such as the Andes.

The understanding of morphological processes controlling the evolution of sand spit reformation after a tsunami impact is a challenging and interesting topic, especially in highly energetic and micro tidal environments. A field campaign performed during December 2012 at the Mataquito River mouth in Chile, allowed us to simultaneously monitor topo-bathymetry evolution, wave climate, tidal range, swash zone dynamics and upper beach face evolution over a portion of its sand spit. A video system was set up for a continuous and long-term monitoring of the evolution of the river mouth and sand spit. Primarily, in this work we focus on the application of a video-derived shoreline detection method to assess shoreline evolution and beach cusps migration at hourly scales. We test the method performance on short-term episodic migration of beach cusps recorded during the campaign. Beach face variations at a daily scale were observed, which can be attributed to the migration of beach cusps in the alongshore direction, and linked to wave forcing and alongshore sediment transport.

Introducción: la Organización Mundial de la Salud proyectó para el año 2015 que 3.000 millones de adultos en el mundo presentarán malnutrición por exceso. Esta situación debe ser considerada, especialmente en el fortalecimiento de los programas de salud existentes destinados a usuarios con estas patologías. Objetivo: interpretar la percepción de estudiantes universitarios con malnutrición por exceso, de los factores que condicionan su alimentación. Materiales y métodos: utilizando un diseño cualitativo del tipo fenomenológico, se realizan entrevistas semiestructuradas a 16 alumnos pertenecientes a la Universidad Católica de la Santísima Concepción durante el año 2010, que cumplieron con los requisitos de ingreso al estudio y firmaron el consentimiento informado. Resultados: entre las condicionantes que se perciben como influyentes en la alimentación de los estudiantes entrevistados se encuentran la limitada disponibilidad de tiempo durante la vida universitaria; el grupo familiar; los amigos; el alto costo y una reducida oferta de alimentos saludables dentro del establecimiento educacional; situaciones de estrés académico y el lugar de residencia. Conclusiones: a excepción de la familia, las condicionantes de la alimentación identificadas por los entrevistados son interpretadas como desfavorables para mantener una alimentación saludable y un control adecuado del peso corporal.

Real-time estimation of the modulus of elasticity (E) in paper machines would enable it to be controlled, improving final product quality and reducing the occurrence of sheet breaks. This paper develops a novel topology to estimate E on web machines based on an adaptive observer structure that combines model reference adaptive control with a closed-loop observer using field signals such as tension force, velocity/position, and torque. The evaluation of the proposed topology is performed on the dryer-calender span of the dry-end section of a lightweight coated paper machine. Results show a fast and accurate estimation of E, confirming the robustness of the adaptive observer structure.

In this study, the influence of zeolite surface sites on the adsorption of volatile organic compounds (VOCs) is evaluated. Chilean natural zeolite of mordenite kind (86% mordenite, and 14% quartz) is used as a parent material. It is chemically modified using hydrochloric acid (2.4 mol dm−3) and thermally out-gassed at 550 °C. Textural characteristics are determined by nitrogen adsorption at 77 K. Acid–base properties of mordenite surface sites are assessed by temperature-programmed desorption, using ammonia and carbon dioxide as the base and acid probe molecules, respectively. Diffuse reflectance infrared Fourier transform spectroscopy studies applied here provide key information to understand surface interactions among adsorbed VOC molecules and active sites of mordenite samples. The presence of moisture reduces mordenite adsorption capacity toward VOCs. Results indicate that Brønsted and Lewis acid sites of mordenite surface could be mainly responsible of the abatement of VOCs. Weak base aromatic VOC molecules such as benzene, toluene and p-xylene seem to be adsorbed by a surface mechanism that includes interaction with Brønsted acid sites in the form of proton-donating hydroxyl groups of mordenite surface, forming hydrogen bonds; and with Lewis acid sites, generating a Lewis acid–base adduct.

In this paper we introduce and analyze a new mixed finite element method for the two-dimensional Brinkman model of porous media flow with mixed boundary conditions. We use a dual-mixed formulation in which the main unknown is given by the pseudostress. The original velocity and pressure unknowns are easily recovered through a simple postprocessing. In addition, since the Neumann boundary condition becomes essential, we impose it in a weak sense, which yields the introduction of the trace of the fluid velocity over the Neumann boundary as the associated Lagrange multiplier. We apply the Babuška–Brezzi theory to establish sufficient conditions for the well-posedness of the resulting continuous and discrete formulations. In particular, a feasible choice of finite element subspaces is given by Raviart–Thomas elements of order for the pseudostress, and continuous piecewise polynomials of degree for the Lagrange multiplier. We also derive a reliable and efficient residual-based a posteriori error estimator for this problem. Suitable auxiliary problems, the continuous inf-sup conditions satisfied by the bilinear forms involved, a discrete Helmholtz decomposition, and the local approximation properties of the Raviart–Thomas and Clément interpolation operators are the main tools for proving the reliability. Then, Helmholtz’s decomposition, inverse inequalities, and the localization technique based on triangle-bubble and edge-bubble functions are employed to show the efficiency. Finally, several numerical results illustrating the performance and the robustness of the method, confirming the theoretical properties of the estimator, and showing the behaviour of the associated adaptive algorithm, are provided.

The conversion of syngas into dimethyl ether has been studied over physical mixtures of a Cu/ZnO based catalyst and a zeolite. Theta-1, ZSM-23, ferrierite, ZSM-5 and mordenite were used. The zeolites were separated after reaction and characterised by temperature programmed oxidation, XRD, and GC–MS of the entrained hydrocarbons. Theta-1 and ferrierite were found to have the most stable performance and the highest selectivity to DME. Deactivation is shown to be faster for structures with enough space to accommodate bulky carbonaceous deposits such as mordenite and ZSM-5. Longer diffusion paths associated with larger crystallites also contributed to rapid loss of activity for ZSM-23. The zeolite topology was found to influence the nature of the entrained alkylbenzenes.

The capability to predict the long term evolution of coastal state parameters can be severely affected by neglecting major geomorphic forcings. Among these, the effect of tsunamis as been largely neglected along the Chilean coast. In this contribution, we present a qualitative and descriptive assessment of the sudden change induced by the tsunami on a coastal location in Central Chile, and the consequent recovery process. The latter is driven mostly by strong wave forcing, with a very fast recovery capactity. The necessity and consequences of including tsunamis in long term evaluations fo coastal morphology are briefly discussed.

Condensate accumulated inside dryer cylinders will produce an increased power demand and eventually the inability of the dryer drive to accelerate the section. In a previous paper, these authors presented an online estimation algorithm capable of detecting the presence of condensate during a section starting. In this paper, a complete set of tests is run over two experimental cylinders covering up to 40% of cylinder volumes, and the complete set of power curves are reported and analyzed. Specifically, the presence of a combined cascading-rimming region in the medium to high condensate loads is confirmed. This combined mode modifies the pattern followed by the maximum power in the low condensate region. Using these data, high-order and simplified correlations are proposed for the estimation of condensate in flooded dryer cylinders. These new correlations increase the capacity of the online estimation algorithm to give good estimations of the condensate load present inside the dryer cylinders up to 55 mm of rim thickness.

Detailed video images and ADCP measurements were used to describe the processes of suspended sediment transport by the Mataquito River into the Pacific Ocean. It is found that, in the absence of fluvial flood discharges, suspended sediment transport to the sea only takes place during low tide periods and it is characterized by pulses of different frequencies that in turn are related to the spatial velocity distribution at the river inlet. It was observed that at low tide the highest velocities are near the mouth of the river, presenting an heterogeneous spatial distribution. In this high speed zone, we hypothesized the shear stresses are big enough to re-suspend fine sediment that is transported into the ocean by the main river current. A simple conceptual explanation based on these findings is presented, seeking to explain the observed dynamic equilibrium of the Mataquito River inlet after the significant alterations produced by the 2010 M8.8 earthquake and tsunami.

Trials were conducted in circular tanks used in aquaculture (1.2 m diameter and 0.4 of useful depth) in order to evaluate the effect of different water injection devices on the tangential velocity of the water, its uniformity pattern, the mixing time and the removal of solids through the bottom drain. Two injection devices, without fishes, were evaluated at the tank: a Vertical Spray, considered as standard in aquaculture and an eductor (Jet-Mixing Eductor) which is used in chemical and petrochemical industry to homogenize and keep in movement great volumes of water. The devices were evaluated under the same operating conditions: inlet flow of 4, 6 and 8 l/min and water injection angle of 0° and 45°. In each trial, the water velocity inside the tank was measured, also the mixing time and the time in which the 100% of pellets of fish food were eliminated from the tank through the bottom drain. The results indicate that, for all inlet flows, the eductor operating at 45° presents significantly (p < 0.001) better result in terms of hydraulic variables such as tangential velocity, uniformity, mixing time and solids removal time from the tank (self-cleaning effect). In the case of eductors, although an increase of inlet flow produces improvements of hydraulic variables, a change of water injection angle, from 0° to 45°, produces significantly better results (p < 0.001). Differences of hydraulic performance between the eductor and Vertical Spray are mainly owing to the multiplicative effect of the outlet flow that is generated by the eductor. This means that, for similar values of impulse force and water velocity at the exit of the nozzle injection (V2), the eductors generate significantly higher tangential velocity and uniformity, lower mixing times and secondary flow patterns, which ensure the self-cleaning of solid waste. In terms of power consumption, eductors overcome Vertical Spray in the trial performed. However, when comparing them under equal requirements of hydraulic performances (velocity, mix and/or self-cleaning), eductors present the same or lower energy consumption. Comparatively eductors would generate, under similar operating conditions, clear benefits for produced species in aquaculture, by generating hydraulic conditions that ensure a better quality of water and patterns and uniformity of velocity, which are more suitable for their health and normal growth.

It is known that the principal Poincaré Pontryagin function is generically an Abelian integral. We give a sufficient condition on monodromy to ensure that it is also an Abelian integral in non-generic cases. In non-generic cases it is an iterated integral. Uribe (2006 J. Dyn. Control. Syst. 12 109–34, 2009 J. Diff. Eqns 246 1313–41) gives in a special case a precise description of the principal Poincaré Pontryagin function, an iterated integral of length at most 2, involving logarithmic functions with only 1 ramification at a point at infinity. We extend this result to some non-isomonodromic families of real Morse polynomials.

Different sets of parameters and conceptualizations of a basin can give equally good results in terms of predefined objective functions. Therefore, a need exists to tackle equifinality and quantify the uncertainty bands of a model. In this paper we use the concepts of equifinality, identifiability and uncertainty to propose a simple method aimed at constraining the equifinal parameters and reducing the uncertainty bands of model outputs, and obtaining physically possible and reasonable models. Additionally, the uncertainty of equifinal solutions is quantified to estimate the amount by which output uncertainty can be reduced by knowing how to discard most of the equifinal solutions of a model. As a study case, a conceptual model of the Chillán basin in Chile is carried out. From the study it is concluded that using identifiability analysis makes it possible to constrain equifinal solutions with reduced uncertainty and realistic models, resulting in a framework that can be recommended to practitioners, especially due to the simplicity of the method.

As hydrological models become more prevalent in water resources planning and management, increasing levels of detail and precision are needed. Currently, reliable models that simulate the hydrological behavior of a basin are indispensable; however, it is also necessary to know the limits of the predictability and reliability of the model outputs. The present study evaluates the influence of uncertainty in the main input variable of the model, rainfall, on the output uncertainty of a hydrological model. Using concepts of identifiability and sensitivity, the uncertainty in the model structure and parameters was estimated. Then, the output uncertainty caused by uncertainties in i) the rainfall amounts and ii) the periods of the rainfall was determined. The main conclusion is that uncertainty in rainfall estimation during rainy periods produces greater output uncertainty. However, in non-rainy periods, the output uncertainty is not very sensitive to the uncertainty in rainfall. Finally, uncertainties in rainfall during the basin filling and emptying periods (Apr. – Jun. and Sep. – Nov., respectively) alter the uncertainty in subsequent periods. Therefore, uncertainties in these periods could result in limited ranges of model predictability.

We consider the Hamiltonian polynomial function H of degree fourth given by either H(x,y,{p_x},{p_y}) = \frac{1}{2}(p_x^2 + p_y^2) + \frac{1}{2}({x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y),\,\,{\text{or}}\,H(x,y,{p_x},{p_y}) = \frac{1}{2}( - p_x^2 + p_y^2) + \frac{1}{2}( - {x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y), where V3(x,y) and V4(x,y) are homogeneous polynomials of degree three and four, respectively. Our main objective is to prove the existence and stability of periodic solutions associated to H using the classical averaging method.

In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

The last great earthquake in northern Chile took place in 1877, and the ensuing tsunami affected not only that region but also Central Chile. For example, the Bay of Concepción, which is located 1,500 km south of the tsunami source, experienced an inundation height of around 3 m. Ports are important in the Chilean economy, due to the fact that a large percentage of Chilean exports (excluding copper) use ports located in Central Chile. With this in mind, the authors investigated the potential effect of an 1877-like tsunami on the main ports of Central Chile. To do this, the dispersive wave model Non-hydrostatic Evolution of Ocean WAVEs was used. In addition, the first tsunami forecast model for Talcahuano, inside the Bay of Concepción, was developed by means of numerical simulation of several events of different moment magnitudes. The results showed that most of the important ports (Valparaiso, San Antonio, San Vicente and Coronel) had inundation heights on the order of just 1 m, while inundation levels in Talcahuano reached up to 3.5 m. The forecast model for Talcahuano uses only earthquake magnitude, focal depth and tide level to determine tsunami inundation heights. In addition, the tsunami arrival time was computed to be 3 h, and the maximum tsunami amplitude takes place at 4 h and 45 min after the earthquake.

Meshing tools are highly complex software for generating and managing geometrical discretizations. Due to their complexity, they have generally been developed by end users – physicists, forest engineers, mechanical engineers – with ad hoc methodologies and not by applying well established software engineering practices. Different meshing tools have been developed over the years, making them a good application domain for Software Product Lines (SPLs). This paper proposes building a domain model that captures the different domain characteristics such as features, goals, scenarios and a lexicon, and the relationships among them. The model is partly specified using a formal language. The domain model captures product commonalities and variabilities as well as the particular characteristics of different SPL products. The paper presents a rigorous process for building the domain model, where specific roles, activities and artifacts are identified. This process also clearly establishes consistency and completeness conditions. The usefulness of the model and the process are validated by using them to generate a software product line of Tree Stem Deformation (TSD) meshing tools. We also present Meshing Tool Generator, a software that follows the SPL approach for generating meshing tools belonging to the TSD SPL. We show how an end user can easily generate three different TSD meshing tools using Meshing Tool Generator.