Optimized Design of Hot Water Storage in Solar Thermal Cooling Facilities

Solar thermal installations can provide a significant contribution to the energy needs of cooling demand of single family buildings. Unfortunately oversizing facility elements is not uncommon. Most of the design flaws concern collector field or auxiliary elements, such as backup boilers or electric resistances inside storage devices. This leads to lower than expected facility COP and SCOP, but also higher cost. Customer dissatisfaction is the result. This paper presents a numerical model of the multiple purpose solar thermal facility installed at Universidad Carlos III de Madrid (UC3M) using the TRNSYS® tool. The solar cooling facility (http://termica.uc3m.es/solar.htm) is completely monitored for its performance characterization in the production of AC, DHW and heating. Operational data for various summer seasons have been recorded, simultaneously with 7 meteorological variables. The experimental facility includes a single effect BrLi absorption chiller working at part load under summer season. TRNSYS is a completely feasible platform for simulating solar facilities and is commonly used by researchers and planners, for its simplicity and ease manipulation. This simulation tool contains general solar cooling elements found in most experimental facilities and has been kept as simple as possible. The model developed aims at analyzing facility elements in order to resize collector field and storage volumes. Furthermore it allows studying different configurations of the facility and the control schemes. These configurations include different hot water storage capacities within the facility allowing comparing with the facility without any kind of storage excepting its own thermal inertia. The simulation has been validated with instantaneous and seasonal experimental data for different summer seasons including 2003, 2004 and 2005. Simulation results show that there is a hot storage tank capacity that optimizes the facility in terms of COP, SCOP and total cold produced. Even with no storage at all, the facility still improves its behavior from current operating conditions. Simulation and experimental results are compared and an optimum configuration of the facility is proposed.Universidad Carlos III de Madrid - ITEA Research GroupPublicad

Simulation of an absorption based solar cooling facility using a geothermal sink for heat rejection

An important issue of solar cooling facilities based on absorption cycles and sometimes not given the necessary attention is the recooling process of the absorber and condenser. This is critical in the overall behaviour of the facility because the condensation and absorption temperatures will affect the COP and cooling capacity of the chiller. Most of the time the recooling process is made by using a wet cooling tower in a closed loop through the absorber and condenser. The use of a wet cooling tower gives good results in terms of cooling capacity and COP, but presents some health risk, like legionella, and its use is restricted to the industrial sector and places where water scarcity is not present. This paper presents the modification of the already validated TRNSYS simulation of a solar cooling facility, implementing a geothermal heat sink instead of the wet cooling tower in order to dissipate the heat generated internally in the absorption chiller. Simulation results shows that a geothermal heat sink composed of 6 boreholes of 100 meters of depth should be sufficient in order to substitute the wet cooling tower, for a typical Spanish single family dwelling.Universidad Carlos III de Madrid - ITEA Research GroupPublicad

To find or not to find a first “significant” job

In this paper we look at school-to-work transitions in Spain. We distinguish between significant and non-significant jobs and show that educational investment enhances access to a first significant job compared to a non-significant one. We also find strong differences between men and women: education attainment provides a clearer differentiating device for women than for men, whatever field of education females choose. These results are tested and confirmed by a multinomial probit model of the probability of achieving both significant and non-significant jobs and by a discrete time duration model of the probability of achieving a significant job.School-to-work transition, job search, youth labour market

La ecuación vivienda-trabajo en las políticas argentinas del nuevo milenio

Este artículo analiza la relación entre vivienda y trabajo en las políticas públicas de hábitat que se definieron e implementaron en el contexto posterior a la crisis argentina de 2001. Con base en el Area Metropolitana de Buenos Aires, se analizan y comparan el Programa Federal de Construcción de Viviendas PFCV, el Programa Federal de Emergencia Habitacional PFEH y la autogestión cooperativa del hábitat Ley 341-PAV durante el período 2003-2008. Se afirma que las variaciones en los modos de articular ambas dimensiones, sumado a las modalidades de producción e inserción urbana de cada caso, adquieren significado más allá del plano estrictamente sectorial, y nos hablan de las características medulares de un orden social desigual tanto como de cauces hacia su posible transformación

Contradiciendo la constitución de la ciudad. Un análisis de los programas habitacionales en la Ciudad de Buenos Aires en el período 2003-2013

El documento que se presenta a continuación nuclea resultados de investigación construidos de manera colectiva por investigadores del Área de Estudios Urbanos (AEU) del Instituto de Investigaciones Gino Germani (IIGG) preocupados por la producción social del hábitat y las políticas públicas que tienen por escenario la Ciudad de Buenos Aires. Se reconstruye, desde una perspectiva histórica, el impacto en el desarrollo urbano que tuvo la transformación neoliberal en la Ciudad de Buenos Aires y el rol que desempeñó el Estado en relación con la definición de su política habitacional en este derrotero. En la primera parte del trabajo, se ofrece una caracterización del déficit habitacional en la Ciudad de Buenos Aires,a partir de un análisis cuantitativo y una descripción del diseño institucional de la política habitacional de la ciudad entre los años 1984 2013, profundizando luego en el análisis de las orientaciones establecidas a partir de 2008. Esto se complementa con un análisis presupuestario para la serie de datos disponibles para el período 2005-2013 y el análisis de la ejecución de cada uno de los programas habitacionales de la Ciudad de Buenos Aires, mostrando continuidades y variaciones entre los años 2001 y 2013. Finalmente, se presentan algunas reflexiones que tienden a aportar a una lectura integrada y tendencial de la política habitacional ejecutada en los últimos años en la Ciudad de Buenos Aires que aporta a la comprensión del crítico cuadro de emergencia habitacional que azota hoy a la urbe

Matching in vitro bioaccessibility of polyphenols and antioxidant capacity of soluble coffee by Boosted Regression Trees

The aim of this study was to evaluate changes in polyphenol profile and antioxidant capacity of five soluble coffees throughout a simulated gastro-intestinal digestion, including absorption through a dialysis membrane. Our results demonstrate that both polyphenol content and antioxidant capacity were characteristic for each type of studied coffee, showing a drop after dialysis. Twenty-seven compounds were identified in coffee by HPLC-MS, while only 14 of them were found after dialysis. Green+roasted coffee blend and chicory+coffee blend showed the highest and lowest content of polyphenols and antioxidant capacity before in vitro digestion and after dialysis, respectively. Canonical correlation analysis showed significant correlation between the antioxidant capacity and the polyphenol profile before digestion and after dialysis. Furthermore, boosted regression trees analysis (BRT) showed that only four polyphenol compounds (5-p-coumaroylquinic acid, quinic acid, coumaroyl tryptophan conjugated, and 5-O-caffeoylquinic acid) appear to be the most relevant to explain the antioxidant capacity after dialysis, these compounds being the most bioaccessible after dialysis. To our knowledge, this is the first report matching the antioxidant capacity of foods with the polyphenol profile by BRT, which opens an interesting method of analysis for future reports on the antioxidant capacity of foods.Fil: Podio, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: López Froilán, Rebeca. Universidad Complutense de Madrid; EspañaFil: Ramirez Moreno, Esther. Universidad Autónoma de Estado de Hidalgo; México. Universidad Complutense de Madrid; EspañaFil: Bertrand, Lidwina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Baroni, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Pérez Rodríguez, María L.. Universidad Complutense de Madrid; EspañaFil: Sánchez Mata, María Cortes. Universidad Complutense de Madrid; EspañaFil: Wunderlin, Daniel A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentin

Desde África a Latinoamérica : encuentro diacrónico de mujeres pintoras

In this article, we propose to explain a situation that presents some complexity because it refers to different levels, all of which are given off to relate the work of women painters which, despite being produced in different times and contexts such geographically distant between them, they share certain biographical circumstances. All in all, we aim to link here all the limitations that they found in their respective artistic paths, it means, exposing their lives, something crucial in the path taken by each of them, from Peru in Latin America, via Canary Islands until South Africa. To this purpose we find appropriate the feminist theory. Which theory is now plural, heterogeneous, once the scheme has exceeded monolithic Eurocentric, of the initial feminism new codes and change the hegemonic discourse. Opens the way for minorities in particular, we are interested in highlighting the importance of autobiography to legitimize marginalized spaces, mostly in the domestic field. What we want, taking into account diversity, is to meet the specific testimony to trace the traits that unifies the experience of a Latin American painter, one of the Canary Islands and Africa

El aprendizaje de la matemática y sus referencias semióticas

Las ciencias fácticas tienen contenido existencial que se corresponde con la realidad. En cambio, las ciencias formales, desde el siglo XIX, sostienen una dimensión sintáctico-formalista, sin contenidos semántico y pragmático. Por lo cual la simbología matemática se presenta como vacía, o sea que no habla de nada. Esto daría derecho al alumno a cuestionar “Y... aprender este lenguaje que no habla de nada, ¿de qué me sirve?” El profesor se verá obligado a demostrar que este lenguaje es fecundo, que puede hablar de todo y que se constituye en la estructura del lenguaje científico porque, precisamente, no habla de nada específico. En este trabajo reflexionamos acerca de las relaciones semánticas y pragmáticas que encierra la Matemática pura y que nos conduce a consideraciones de la ontología matemática, correlacionando genéticamente el pensamiento concreto y el abstracto

Precisión del posicionamiento en interiores utilizando Bluetooth con diferentes técnicas de reconocimiento de patrones

Object indoor location is a field that receives much research effort but that is lacking enough maturity for its integration in popular devices like mobile phones. This paper describes the results of an experiment carried out to compare different pattern recognition algorithms in order to process the information from a set of Bluetooth transmitters, located in fixed positions, with the aim of locating an object in a precise position. Our conclusion is that the best algorithms, among the five we tested, are random forests and model-based clustering, which gave accuracies around 90%. We have also conducted experiments to analyse the influence of the number of Bluetooth transmitters and to determine the sets of features with better performance. The proposed approach is simple and gives 90% of accuracy for locating objects with 1 m precision, making it suitable for a wide range of applications.Facultad de Informátic

Equivalences of Zt×Z22-cocyclic Hadamard matrices

One of the most promising structural approaches to resolving the Hadamard Conjecture uses the family of cocyclic matrices over Zt × Z2 2. Two types of equivalence relations for classifying cocyclic matrices over Zt × Z2 2 have been found. Any cocyclic matrix equivalent by either of these relations to a Hadamard matrix will also be Hadamard. One type, based on algebraic relations between cocycles over any fi- nite group, has been known for some time. Recently, and independently, a second type, based on four geometric relations between diagrammatic visualisations of cocyclic matrices over Zt × Z2 2, has been found. Here we translate the algebraic equivalences to diagrammatic equivalences and show one of the diagrammatic equivalences cannot be obtained this way. This additional equivalence is shown to be the geometric translation of matrix transposition