Mariano Picón Salas: triangulaciones del lugar americano 1930-1950

We introduce the work of Mariano Picón Salas (Venezuela, 1901- 1965), who tries to enlarge the Hispanoamerican tradition —historically focused on the web of transits/obstructions between Europe and Latin America— via a larger triangulation that includes the presence of the culture of the United States. His essays from the period 1930-1950 show how pragmati(ci)sm —understood in Peircean terms as a web of topological transfers of knowledge between the borders of culture— can help to provide a vision that encompasses America as a whole

Composite material behavior using a homogenization double scale method

In this paper, we present a two-scale numerical method in which structures made up of composite materials are simulated. The method proposed lies within the context of homogenization theory and assumes the periodicity of the internal structure of the material. The problem is divided into two scales of different orders of magnitude: A macroscopic scale in which the body and structure of the composite material is simulated, and a microscopic scale in which an elemental volume called a “cell” simulates the material. In this work, the homogenized strain tensor is related to the transformation of the periodicity vectors. The problem of composite materials is posed as a coupled, two-scale problem, in which the constitutive equation of the composite material becomes the solution of the boundary-value problem in the cell domain. Solving various examples found in the bibliography on this subject demonstrates the validity of the method

Numerical simulation of fiber reinforced composite materials––two procedures

In this work, two methodologies for the analysis of unidirectional fiber reinforced composite materials are presented. The first methodology used is a generalized anisotropic large strains elasto-plastic constitutive model for the analysis of multiphase materials. It is based on the mixing theory of basic substance. It is the manager of the several constitutive laws of the different compounds and it allows to consider the interaction between the compounds of the composite materials. In fiber reinforced composite materials, the constitutive behavior of the matrix is isotropic, whereas the fiber is considered orthotropic. So, one of the constitutive model used in the mixing theory needs to consider this characteristic. The non-linear anisotropic theory showed in this work is a generalization of the classic isotropic plasticity theory (A Continuum Constitutive Model to Simulate the Mechanical Behavior of Composite Materials, PhD Thesis, Universidad Politécnica de Cataluña, 2000). It is based in a one-to-one transformation of the stress and strain spaces by means of a four rank tensor. The second methodology used is based on the homogenization theory. This theory divided the composite material problem into two scales: macroscopic and microscopic scale. In macroscopic level the composite material is assuming as a homogeneous material, whereas in microscopic level a unit volume called cell represents the composite (Tratamiento Numérico de Materiales Compuestos Mediante la teorı́a de Homogeneización, PhD Thesis, Universidad Politécnica, de Cataluña 2001). This formulation presents a new viewpoint of the homogenization theory in which can be found the equations that relate both scales. The solution is obtained using a coupled parallel code based on the finite elements method for each scale problem

Tratamiento numérico de materiales compuestos mediante la teoría de homogeneización

El presente trabajo se emmarca dentro de las teorías y métodos que hacen posible la representación por ordenador de los materiales compuesto. Como se sabe, la búsqueda de leyes matemáticas que determinan el comportamiento de esta clase de materiales ha sido objeto de estudio durante varias décadas. Pero, su elavada dificultad conduce a elaborar complejas teorías; o por el contrario, se utlizan grandes simplificaciones cuyo resultado genera modelos poco acertados.Postprint (published version

Tratamiento numérico de los materiales compuestos mediante la teoría de homogeneización

El presente trabajo se emmarca dentro de las teorías y métodos que hacen posible la representación por ordenador de los materiales compuesto. Como se sabe, la búsqueda de leyes matemáticas que determinan el comportamiento de esta clase de materiales ha sido objeto de estudio durante varias décadas. Pero, su elavada dificultad conduce a elaborar complejas teorías; o por el contrario, se utlizan grandes simplificaciones cuyo resultado genera modelos poco acertados.Postprint (published version

Photovoltaic simulation considering building integration parameters

Esta investigación calibra y valida un modelo de sistemas fotovoltaicos monocristalinos en la herramienta computacional System Advisor Model (SAM) para simulación de generación eléctrica, considerando las características meteorológicas en Cuenca (Ecuador), ciudad en altura próxima a la línea ecuatorial. Se obtiene el rendimiento eléctrico al desplegarse paneles fotovoltaicos de características específicas, con inclinaciones que responden a techumbres típicas locales y distintas orientaciones. Se calcula la eficiencia con mediciones in situ durante un período de 18 días, para que, con datos meteorológicos se calibre un archivo climático para el año 2016. Se estiman rendimientos anuales acorde a inclinación y orientación, y a características técnicas de los fotovoltaicos. Se detectan pérdidas por acumulación de suciedad e incremento de temperatura de las placas. Se valida el modelo mediante una regresión lineal, al comparar los valores simulados con los datos obtenidos de mediciones in situ de un panel en posición horizontal. Los resultados indican una pérdida promedio de eficiencia de 2,77 % por condiciones de suciedad y de hasta el 30 % por incremento de temperatura. La validación del modelo mostró un coeficiente de determinación R2 = 0,996 y un RMSE normalizado de 8,16 %. Se concluye además que, por la latitud particular del sitio en estudio, a diferencia de la mayor parte del planeta, la disposición de paneles fotovoltaicos en cualquier orientación considerando pendientes bajas, no reduce significativamente el rendimiento en la generación de energía eléctrica anual.This research calibrates and validates a model for monocrystalline photovoltaic systems in SAM (System Advisor Model) for power generation simulation, considering the meteorological characteristics of Cuenca, Ecuador, close to the equatorial line. The electrical performance is calculated by arranging photovoltaic systems with specific characteristics, with inclinations that respond to conventional local roofing and different orientations. Efficiency is calculated with in-situ measurements over a period of 18 days. Meteorological data were used to calibrate a weather file for the year 2016. Annual yields are estimated according to inclination and orientation, and technical characteristics of the photovoltaic system. Losses are detected due to dirt accumulation and increase in temperature of the panels. The model is validated by linear regression, by comparing the simulated values with the data obtained from in-situ measurements of a reference panel deployed horizontally. The results show an average efficiency loss of 2,77% for dirt conditions and up to 30% for temperature increases. The validation of the model showed a determination coefficient R2=0,996 and a normalized Root Mean Square Error (RMSE) of 8,16%. It is concluded that, because of the particular latitude of the study site, unlike most of the planet, the provision of photovoltaic panels in any orientation considering low slopes, does not significantly reduce the annual power generation performance

Calculating Matter and Recombinant Subjects: The Infinitesimal and the Fractal Fold

Because different mathematical practices are aligned with different ontologies, it matters what kind of mathematics we bring to bear in social theory. This article explores the open and urgent question as to whether and how calculation becomes an inventive practice that doesn't simply serve the control society. In search of a non-axiomatic mathematical problematic, I examine the infinitesimal for its enigmatic role in calculation and show how Deleuze and Guattari use the infinitesimal to (a) rethink the relationship between matter and meaning, and (b) describe a recombinant fractal subject well suited to our digital times. The infinitesimal is a sort of changeling number with one foot in the virtual and one foot in the actual, and thus pivotal to considerations of vitalist new mixtures of number and matter

Water Availability Is the Main Climate Driver of Neotropical Tree Growth

• Climate models for the coming century predict rainfall reduction in the Amazonian region, including change in water availability for tropical rainforests. Here, we test the extent to which climate variables related to water regime, temperature and irradiance shape the growth trajectories of neotropical trees. • We developed a diameter growth model explicitly designed to work with asynchronous climate and growth data. Growth trajectories of 205 individual trees from 54 neotropical species censused every 2 months over a 4-year period were used to rank 9 climate variables and find the best predictive model. • About 9% of the individual variation in tree growth was imputable to the seasonal variation of climate. Relative extractable water was the main predictor and alone explained more than 60% of the climate effect on tree growth, i.e. 5.4% of the individual variation in tree growth. Furthermore, the global annual tree growth was more dependent on the diameter increment at the onset of the rain season than on the duration of dry season. • The best predictive model included 3 climate variables: relative extractable water, minimum temperature and irradiance. The root mean squared error of prediction (0.035 mm.d–1) was slightly above the mean value of the growth (0.026 mm.d–1). • Amongst climate variables, we highlight the predominant role of water availability in determining seasonal variation in tree growth of neotropical forest trees and the need to include these relationships in forest simulators to test, in silico, the impact of different climate scenarios on the future dynamics of the rainforest