El género epistolar en la prensa como visión ciudadana de la esfera pública en Colombia

A partir de un análisis temático inductivo, este artículo explora la visión ciudadana sobre la esfera pública expresada en las cartas de los lectores de los diarios El Tiempo y El Heraldo de Colombia. Los resultados muestran cómo la identidad colectiva de los lectores apareció en forma transversal en las cartas, para dar cuenta de una comunidad de adultos que se autodefine como “colombianos de bien”. El análisis reveló dos unidades de significado: posturas sobre la administración de lo público y antagonismos en la esfera pública, centrada en el conflicto político con las guerrillas. A través de estas se pudieron hacer visibles los llamamientos vívidos de los lectores al gobierno, funcionarios públicos, actores al margen de la ley y a sus compatriotas, para movilizarse para exigir cambios sociales largamente esperados.

China, perspective from the European Union: commitment and cooperation

The bilateral relationship between the EU and China has a tendency toward growth in recent years. At present, China’s economic development is at a critical transition period for deepening reform in the economic structure. The economic and trade cooperation with the countries of the European Union has a significant influence for the stability of trade development and economic growth. Therefore China tries to expand cooperation and eliminate the issues and difficulties that exist, it will more often to promote cooperation between the two parties towards deeper into various cooperative areas.

Radiological and material characterization of high volume fly ash concrete

The main goal of research presented in this paper was the material and radiological characterization of high volume fly ash concrete (HVFAC) in terms of determination of natural radionuclide content and radon emanation and exhalation coefficients. All concrete samples were made with a fly ash content between 50% and 70% of the total amount of cementitious materials from one coal burning power plant in Serbia. Physical (fresh and hardened concrete density) and mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity) of concrete were tested. The radionuclide content (226Ra, 232Th and 40K) and radon massic exhalation of HVFAC samples were determined using gamma spectrometry. Determination of massic exhalation rates of HVFAC and its components using radon accumulation chamber techniques combined with a radon monitor was performed. The results show a beneficial effect of pozzolanic activity since the increase in fly ash content resulted in an increase in compressive strength of HVFAC by approximately 20% for the same mass of cement used in the mixtures. On the basis of the obtained radionuclide content of concrete components the I -indices of different HVFAC samples were calculated and compared with measured values (0.27e0.32), which were significantly below the recommended 1.0 index value. The prediction was relatively close to the measured values as the ratio between the calculated and measured I-index ranged between 0.89 and 1.14. Collected results of mechanical and radiological properties and performed calculations clearly prove that all 10 designed concretes with a certain type of fly ash are suitable for structural and non-structural applications both from a material and radiological point of view.

A Generalized Fuzzy Linguistic Model for Predicting Component Concentrations in an Optical Gas Sensing System

Motivated by environmental protection concerns, monitoring the flue gas of thermal power plant is now often mandatory due to the need to ensure that emission levels stay within safe limits. Optical based gas sensing systems are increasingly employed for this purpose, with regression techniques used to relate gas optical absorption spectra to the concentrations of specific gas components of interest (NOx, SO2 etc.). Accurately predicting gas concentrations from absorption spectra remains a challenging problem due to the presence of nonlinearities in the relationships and the high-dimensional and correlated nature of the spectral data. This article proposes a generalized fuzzy linguistic model (GFLM) to address this challenge. The GFLM is made up of a series of “If-Then” fuzzy rules. The absorption spectra are input variables in the rule antecedent. The rule consequent is a general nonlinear polynomial function of the absorption spectra. Model parameters are estimated using least squares and gradient descent optimization algorithms. The performance of GFLM is compared with other traditional prediction models, such as partial least squares, support vector machines, multilayer perceptron neural networks and radial basis function networks, for two real flue gas spectral datasets: one from a coal-fired power plant and one from a gas-fired power plant. The experimental results show that the generalized fuzzy linguistic model has good predictive ability, and is competitive with alternative approaches, while having the added advantage of providing an interpretable model.

A generalized fuzzy linguistic model for predicting component concentrations in an optical gas sensing system

Motivated by environmental protection concerns, monitoring the flue gas of thermal power plant is now often mandatory due to the need to ensure that emission levels stay within safe limits. Optical based gas sensing systems are increasingly employed for this purpose, with regression techniques used to relate gas optical absorption spectra to the concentrations of specific gas components of interest (NO_x, SO₂ etc.). Accurately predicting gas concentrations from absorption spectra remains a challenging problem due to the presence of nonlinearities in the relationships and the high-dimensional and correlated nature of the spectral data. This article proposes a generalized fuzzy linguistic model (GFLM) to address this challenge. The GFLM is made up of a series of “If-Then” fuzzy rules. The absorption spectra are input variables in the rule antecedent. The rule consequent is a general nonlinear polynomial function of the absorption spectra. Model parameters are estimated using least squares and gradient descent optimization algorithms. The performance of GFLM is compared with other traditional prediction models, such as partial least squares, support vector machines, multilayer perceptron neural networks and radial basis function networks, for two real flue gas spectral datasets: one from a coal-fired power plant and one from a gas-fired power plant. The experimental results show that the generalized fuzzy linguistic model has good predictive ability, and is competitive with alternative approaches, while having the added advantage of providing an interpretable model.

Development of a Rational Characterization Method for Iowa Fly Ash, HR-286, Annual Progress Report 2, 1987

The following report summarizes research activities on the project for the period December 1, 1986 to November 30, 1987. Research efforts for the second year deviated slightly from those described in the project proposal. By the end of the second year of testing, it was possible to begin evaluating how power plant operating conditions influenced the chemical and physical properties of fly ash obtained from one of the monitored power plants (Ottumwa Generating Station, OGS). Hence, several of the tasks initially assigned to the third year of the project (specifically tasks D, E, and F) were initiated during the second year of the project. Manpower constraints were balanced by delaying full scale implementation of the quantitative X-ray diffraction and differential thermal analysis tasks until the beginning of the third year of the project. Such changes should have little bearing on the outcome of the overall project.

Urbaania energiaa. Suvilahden, Hanasaaren A- ja Vuosaaren voimalaitokset osana helsinkiläistä kaupunkiympäristöä

Tutkimus koostuu kolmen Helsingissä sijaitsevan, kolmena eri aikakautena, 1910-, 1950- ja 1990-luvuilla, rakennetun voimalaitoksen arkkitehtuurista ja rakennustyypistä sekä niiden eroista ja erityisyyksistä samoin kuin näiden voimalaitosten roolista ja vaikutuksesta Helsingin kaupunkisuunnitteluun ja -rakentamiseen, kaupunkikuvaan sekä ympäristöestetiikkaan. Tutkimus on rajattu koskemaan erityyppisten voimalaitosten osalta yksinomaan kolmea helsinkiläistä kaupungissa sijaitsevaa voimalaitosta, Suvilahtea, Hanasaari-A:ta ja Vuosaaren A- ja B-laitoksia. Tutkimuksen tarkoituksena on ensinnäkin selvittää sekä periaatteessa että edellä mainittujen kolmen esimerkkikohteen kautta seikkoja, jotka ovat vaikuttaneet kunkin voimalaitoksen arkkitehtuuriin ja rakennustyyppiin kunakin aikakautena. Kaupunkivoimalan olennaiset elementit ovat korkea savupiippu, mittava polttoainevarasto sekä massiiviset rakennusmassat, jotka vaativat runsasta maankäyttöä. Toiseksi tutkimuksessa paneudutaan kaupunkisuunnitteluun laitoksen sijoittumisen osalta sekä ajallisesti että paikallisesti. Kolmanneksi selvitetään kaupunkikuvallisia ja ympäristöesteettisiä seikkoja, sekä niiden vaikutusten kehitystä voimalaitoksen toteutuksen ja nykyhetken kesken. Tutkimuksessa haetaan vastausta kysymykseen, miten Helsingissä sijaitseva voimalaitos arkkitehtuuriltaan, rakennustyypiltään ja sijoitukseltaan on soveltunut ja jatkossa soveltuu kaupunkisuunnittelun kannalta kaupunkikuvallisesti sekä ympäristöesteettisesti kyseiseen kaupunkiympäristöön. Tutkimus selvittää myös sitä ilmeistä ristiriitaa, joka syntyy kaupungin kehittyessä ja laajentuessa, jolloin voimalaitos infrastruktuurinsa ja useimmiten suunnattoman kokonsa vuoksi edustaa pysyvyyttä rakentuvan alueen sisällä. Tässä yhteydessä tutkimuksessa pohditaan esimerkkikohteiden avulla voimalaitoksen säilyttämistä puoltavia rakennustaiteellisia arvoja, mahdollista korvattavuutta, ja siinä yhteydessä haetaan vastauksia jäljelle jäävälle laitosrakennukselle kaupunkisuunnittelun kannalta asetettavista uusiokäytön vaatimuksista ja mahdollisuuksista. Tutkimuksen metodologia on sekä kvantitatiivisesti että kvalitatiivisesti historiallinen, esimerkkikohteita käsiteltäessä tarvittavassa määrin myös mikrohistoriallinen.

Sistema de predição de alarmes em processos industriais por classificação não-supervisionada

Um sistema de predição de alarmes com a finalidade de auxiliar a implantação de uma política de manutenção preditiva industrial e de constituir-se em uma ferramenta gerencial de apoio à tomada de decisão é proposto neste trabalho. O sistema adquire leituras de diversos sensores instalados na planta, extrai suas características e avalia a saúde do equipamento. O diagnóstico e prognóstico implica a classificação das condições de operação da planta. Técnicas de árvores de regressão e classificação não-supervisionada são utilizadas neste artigo. Uma amostra das medições de 73 variáveis feitas por sensores instalados em uma usina hidrelétrica foi utilizada para testar e validar a proposta. As medições foram amostradas em um período de 15 meses.

CHARACTERIZATION OF RADIATION DAMAGE TO A NOVEL PHOTONIC CRYSTAL SENSOR

New methods of nuclear fuel and cladding characterization must be developed and implemented to enhance the safety and reliability of nuclear power plants. One class of such advanced methods is aimed at the characterization of fuel performance by performing minimally intrusive in-core, real time measurements on nuclear fuel on the nanometer scale. Nuclear power plants depend on instrumentation and control systems for monitoring, control and protection. Traditionally, methods for fuel characterization under irradiation are performed using a “cook and look” method. These methods are very expensive and labor-intensive since they require removal, inspection and return of irradiated samples for each measurement. Such fuel cladding inspection methods investigate oxide layer thickness, wear, dimensional changes, ovality, nuclear fuel growth and nuclear fuel defect identification. These methods are also not suitable for all commercial nuclear power applications as they are not always available to the operator when needed. Additionally, such techniques often provide limited data and may exacerbate the phenomena being investigated. This thesis investigates a novel, nanostructured sensor based on a photonic crystal design that is implemented in a nuclear reactor environment. The aim of this work is to produce an in-situ radiation-tolerant sensor capable of measuring the deformation of a nuclear material during nuclear reactor operations. The sensor was fabricated on the surface of nuclear reactor materials (specifically, steel and zirconium based alloys). Charged-particle and mixed-field irradiations were both performed on a newly-developed “pelletron” beamline at Idaho State University's Research and Innovation in Science and Engineering (RISE) complex and at the University of Maryland's 250 kW Training Reactor (MUTR). The sensors were irradiated to 6 different fluences (ranging from 1 to 100 dpa), followed by intensive characterization using focused ion beam (FIB), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to investigate the physical deformation and microstructural changes between different fluence levels, to provide high-resolution information regarding the material performance. Computer modeling (SRIM/TRIM) was employed to simulate damage to the sensor as well as to provide significant information concerning the penetration depth of the ions into the material.

Estudo numérico do impacto das emissões veiculares e fixas da cidade de Manaus nas concentrações de poluentes atmosféricos da região amazônica

The main aim of this study was to evaluate the impact of the urban pollution plume from the city of Manaus by emissions from mobile and stationary sources in the atmospheric pollutants concentrations of the Amazon region, by using The Weather Research and Forecasting with Chemistry (WRF-Chem) model. The air pollutants analyzed were CO, NOx, SO2, O3, PM2.5, PM10 and VOCs. The model simulations have been configured with a grid spacing of 3 km, with 190 x and 136 y grid points in horizontal spacing, centered in the city of Manaus during the period of 17 and 18 of March 2014. The anthropogenic emissions inventories have gathered from mobile sources that were estimated the emissions of light and heavy-duty vehicles classes. In addition, the stationary sources have considered the thermal power plants by the type of energy sources used in the region as well as the emissions from the refinery located in Manaus. Various scenarios have been defined with numerical experiments that considered only emissions by biogenic, mobile and stationary sources, and replacement fuel from thermal power plant, along with a future scenario consisting with twice as much anthropogenic emissions. A qualitative assessment of simulation with base scenario has also been carried out, which represents the conditions of the region in its current state, where several statistical methods were used in order to compare the results of air pollutants and meteorological fields with observed ground-based data located in various points in the study grid. The qualitative analysis showed that the model represents satisfactorily the variables analyzed from the point of view of the adopted parameters. Regarding the simulations, defined from the base scenarios, the numerical experiments indicate relevant results such as: it was found that the stationary sources scenario, where the thermal power plants are predominant, resulted in the highest concentrations, for all air pollutants evaluated, except for carbon monoxide when compared to the vehicle emissions scenario; The replacement of the energy matrix of current thermal power plants for natural gas have showed significant reductions in pollutants analyzed, for instance, 63% reductions of NOx in the contribution of average concentration in the study grid; A significant increase in the concentrations of chemical species was observed in a futuristic scenario, reaching up to a 81% increase in peak concentrations of SO2 in the study area. The spatial distributions of the scenarios have showed that the air pollution plume from Manaus is predominantly west and southwest, where it can reach hundreds of kilometers to areas dominated by original soil covering.

Computational modelling of non-equilibrium condensing steam flows in low-pressure steam turbines

The steam turbines play a significant role in global power generation. Especially, research on low pressure (LP) steam turbine stages is of special importance for steam turbine man- ufactures, vendors, power plant owners and the scientific community due to their lower efficiency than the high pressure steam turbine stages. Because of condensation, the last stages of LP turbine experience irreversible thermodynamic losses, aerodynamic losses and erosion in turbine blades. Additionally, an LP steam turbine requires maintenance due to moisture generation, and therefore, it is also affecting on the turbine reliability. Therefore, the design of energy efficient LP steam turbines requires a comprehensive analysis of condensation phenomena and corresponding losses occurring in the steam tur- bine either by experiments or with numerical simulations. The aim of the present work is to apply computational fluid dynamics (CFD) to enhance the existing knowledge and understanding of condensing steam flows and loss mechanisms that occur due to the irre- versible heat and mass transfer during the condensation process in an LP steam turbine. Throughout this work, two commercial CFD codes were used to model non-equilibrium condensing steam flows. The Eulerian-Eulerian approach was utilised in which the mix- ture of vapour and liquid phases was solved by Reynolds-averaged Navier-Stokes equa- tions. The nucleation process was modelled with the classical nucleation theory, and two different droplet growth models were used to predict the droplet growth rate. The flow turbulence was solved by employing the standard k-ε and the shear stress transport k-ω turbulence models. Further, both models were modified and implemented in the CFD codes. The thermodynamic properties of vapour and liquid phases were evaluated with real gas models. In this thesis, various topics, namely the influence of real gas properties, turbulence mod- elling, unsteadiness and the blade trailing edge shape on wet-steam flows, are studied with different convergent-divergent nozzles, turbine stator cascade and 3D turbine stator-rotor stage. The simulated results of this study were evaluated and discussed together with the available experimental data in the literature. The grid independence study revealed that an adequate grid size is required to capture correct trends of condensation phenomena in LP turbine flows. The study shows that accurate real gas properties are important for the precise modelling of non-equilibrium condensing steam flows. The turbulence modelling revealed that the flow expansion and subsequently the rate of formation of liquid droplet nuclei and its growth process were affected by the turbulence modelling. The losses were rather sensitive to turbulence modelling as well. Based on the presented results, it could be observed that the correct computational prediction of wet-steam flows in the LP turbine requires the turbulence to be modelled accurately. The trailing edge shape of the LP turbine blades influenced the liquid droplet formulation, distribution and sizes, and loss generation. The study shows that the semicircular trailing edge shape predicted the smallest droplet sizes. The square trailing edge shape estimated greater losses. The analysis of steady and unsteady calculations of wet-steam flow exhibited that in unsteady simulations, the interaction of wakes in the rotor blade row affected the flow field. The flow unsteadiness influenced the nucleation and droplet growth processes due to the fluctuation in the Wilson point.