139,225 research outputs found
Optimization of the mass ratio and melting temperature of PCMs integrated in Salt Gradient Solar Ponds
No full textPhase Change Materials (PCMs) are promising materials to increase the storage capacity of solar energy-based systems, such as Salt Gradient Solar Ponds (SGSPs), as they are characterized by a large latent heat during the solid-liquid phase change. This paper introduces an optimization study for PCM integration in SGSP, in terms of PCM mass ratio (14 %, 19 %, 28 % and 47 %) in the lower convective zone and PCM melting temperature (35 °C, 44 °C and 50 °C). Numerically, a 2D model is developed, consisting in the continuity equation as well on momentum, thermal energy and diffusion equations. In order to validate this numerical model, an experimental campaign of a parallelepiped SGSP with PCM capsules in the bottom is constructed. The latter is tested for two PCMs (RT35HC and RT44HC) and under different climatic conditions of March and June. Numerical and experimental have been compared in which the maximum average relative error does not exceed 4.62 %, which ensures a positive validation. The optimization returns that the final liquid fraction of PCM decreases both increasing the mass ratio and melting temperature. Higher mass ratios reduce the final temperature of the PCM (49.5 °C with 14 % and 42 °C with 47 % for RT35HC), and also with higher melting temperatures reduce the thermal energy stored, since the pond tends to work only as a sensible energy storage system
Effects of Double-Diffusive Convection on Calculation Time and Accuracy Results of a Salt Gradient Solar Pond: Numerical Investigation and Experimental Validation
No full textThe main aim of this study is to investigate numerically and experimentally the effects of double-diffusive convection on calculation time and accuracy results of a Salt Gradient Solar Pond (SGSP). To this end, two-numerical models are developed based on the Fortran programming language. The first one is based on energy balance neglecting the development of double-diffusive convection, while the second is two-dimensional and is based on Navier-Stokes, heat, and mass transfer equations considering the development of double-diffusive convection. The heat losses via the upper part, bottom, and vertical walls, as well as the internal heating of saltwater, are considered. In order to validate and compare both numerical models, a laboratory-scale SGSP is designed, built, and tested indoors for 82 h. Results indicate that the two numerical models developed can predict the SGSP thermal behavior with good accuracy. Furthermore, the average relative error between experimental and numerical results is around 9.39% for Upper Convective Zone (UCZ) and 2.92% for Lower Convective Zone (LCZ) based on the first model. This error reduces to about 5.98% for UCZ and 3.74% for LCZ by using the second model. Consequently, the neglect of double-diffusive convection in the SGSP modeling tends to overestimate the thermal energy stored in the storage zone by about 4.3%. Based on the calculation time analysis, results show that the second model returns a calculation time hundreds of times larger than the first one and, accordingly, an increase in computational cost
Spatially-localized time dependent solutions including turbulence and their interactions in 2D Kolmogorov flow
No full textIn 2D Kolmogorov flow in small aspect ratio domains, spatially-localized solutions such as kink, traveling or time-dependent kink-antikink pars coexist. However, the conservation of the flow rate in the y direction strongly restrict combination of localized solutions and their positioning. We find that by adding a homogeneous flow U y their positioning is controlled and each of localized solutions including a spatially-localized chaos is isolated. Numerical results suggest that these isolated solutions can be elements constructing a whole flow
Characteristics of overlap region in high-Reynolds number turbulent channel flow
No full textDirect numerical simulation of the fully developed turbulent channel flows have been carried out at the Reynolds number based on the friction velocity and the channel half width, 2000, 4000 and 8000. A hybrid 10th order accurate finite difference scheme in the stream and spanwise directions, and a second-order scheme in the wall-normal direction is adapted as the spatial discretization method. We observed the plateau profiles in the indicator function corresponded to the von Karman constant. Furthermore, second peak of streamwise pre-multiplied spectra were appeared in the same wall normal height, 300 < y+ < 600, in case of Re = 4000. Nevertheless, the effects of the lager than the channel half height scale on the streamwise turbulent intensity are fixed contributions without dependence on Reynolds number. These results suggested that the new streamwise vortexes are formed between buffer layer and outer layer with increasing of Reynolds number
La 'circunstancia' de 'Herederos y Pretendientes
No full textIn June 2010, the Ortega y Gasset Foundation hosted a Conference about the “Spanish Philosophical Transition” in order to debate the book of Francisco Vázquez, La filosofía española. Herederos y Pretendientes. Una lectura sociológica (1963-1990), recently published. This paper is the author’s response to criticism raised in the Conference and to published reviews received by this book. First, the author summarized the argument of Herederos y pretendientes. Secondly he responds and takes into account the most important objections against the book’s hypothesis and methodology. Finally the author evaluates the favorable judgments received by the book and suggests the limits of the historian’s task.Fundación Ortega y Gasset-Marañó
Author self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
Overview of the Author Profiling Task at PAN 2013
No full text[EN] This overview presents the framework and results for the Author Profiling
task at PAN 2013. We describe in detail the corpus and its characteristics,
and the evaluation framework we used to measure the participants performance to
solve the problem of identifying age and gender from anonymous texts. Finally,
the approaches of the 21 participants and their results are described.The author profiling task @PAN-2013 was an activity of the WIQ-EI IRSES project (Grant No. 269180) within the FP 7 Marie Curie People Framework of the European Commission. We want to thank the Forensic Lab of the Universitat Pompeu Fabra Barcelona for sponsoring the award for the winner team. The work of the first author was partially funded by Autoritas Consulting SA and by Ministerio de Economía y Competitividad de España under grant ECOPORTUNITY IPT-2012-1220-430000. The work of the second author was in the framework the DIANA-APPLICATIONS-Finding Hidden Knowledge in Texts: Applications (TIN2012-38603-C02-01) project, and the VLC/CAMPUS Microcluster on Multimodal Interaction in Intelligent Systems. The work of fifth author was funded in part by the Swiss National Science Foundation (SNF) project "Mining Conversational Content for Topic Modelling and Author Identification (ChatMiner)" under grant number 200021_130208.Rangel, F.; Rosso, P.; Koppel, M.; Stamatatos, E.; Inches, G. (2013). Overview of the Author Profiling Task at PAN 2013. CLEF Conference on Multilingual and Multimodal Information Access Evaluation. 352-365. https://riunet.upv.es/handle/10251/46636S35236
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
Semana Santa y su simbología. 5 Segunda época Año 3 (2019) enero-junio. Rutas de Campo. Trabajo de Campo: Iztapalapa: memoria y cultura
No full textLos dos grandes momentos en torno a los cuales gira la cosmovisión católica, el nacimiento de Jesús y su muerte, han dado lugar, el primero, a la celebración de la Navidad, y el segundo, a la conmemoración de Semana Santa. En este texto nos ocuparemos de los años finales de la vida de Jesús, pues es precisamente Semana Santa la celebración litúrgica con que se recuerda su Pasión y su muerte. Recordemos que, en este contexto, el término “pasión” hace referencia al sufrimiento y a la serie de tormentos a que fue sometido Jesús poco antes de su muerte en la cruz, que todos conocemos.Altamirano, Ignacio Manuel (1974). Paisajes y leyendas. Tradiciones y costumbres de México. México: Porrúa.Calendario de fiestas tradicionales (1988). México: Dirección General de Culturas Populares-SEP.Calendario Litúrgico Pastoral 1991 (1990). México: Obra Nacional de la Buena Prensa.Campos, Rubén M. (1929). El folklore literario en México. Investigación de la producción literaria popular. México: Talleres Gráficos de la Nación._____ (1958). “Semana Santa”. En Fiesta. México: Talleres de la Secretaría de Hacienda.Castelló Iturbide, María Teresa (1958). “El altar del Viernes de Dolores”. En Fiesta. México: Talleres de la Secretaría de Hacienda.Catalán Blanco, Juan Carlos (s.f.). “Las fiestas de carnestolendas y la celebración de la Semana Santa en la época colonial” [inédito]. s.l.: Dirección General de Culturas Populares de Guerrero-SEP.Cid, Carlos, y Manuel Riu (1965). Historia de las religiones. Barcelona: Sopena._____ (1987). Compendio de historia sagrada y de la historia de la Iglesia. México: Progreso.Crumrine N., Roos (1979). “Cuaresma”. En Gran Enciclopedia Rialp. Madrid: Rialp.Estrada, Genaro (1945). Visionario de la Nueva España. México: Patria.Estrada, Humberto (1985). “La cuaresma” [inédito]. s.l.: Dirección General de Culturas Populares-SEP.Foster, George M. (1962). Cultura y conquista. Xalapa: Universidad Veracruzana.García Cubas, Antonio (1945). El libro de mis recuerdos. México: Patria.González Obregón, Luis (1936). Croniquillas de la Nueva España. México: Botas.____(1941). Las calles de México. México: Botas.Horcasitas, Fernando (1974). El teatro náhuatl: época novohispana y moderna. México: IIH-UNAM.Iglesias y Cabrera, Sonia C. (1996). Tradiciones de Cuaresma y Semana Santa. México: Museo Nacional de Culturas Populares-Dirección General de Culturas Populares._____ (2001). La semana Santa en México. Con la muerte en la cruz. México: Dirección General de Culturas Populares.Lercaro, Giacomo (1960). ¿Cuál es el vocabulario de la liturgia católica? México: Novaro.Macgowan, Kenneth, y William Melnitz (1964). Las edades de oro del teatro. México: FCE.Mendieta, Gerónimo de (1945). Historia eclesiástica indiana. México: Salvador Sánchez.Mendoza, Vicente T., y Adalberto Fuentes Cruz (1945). “Drama de la Pasión intitulado: el drama del Gólgota, que se representa en la delegación de Milpa Alta, D.F.”. Anuario de la Sociedad Folklórica de México, 6.Moreno Toscano, Alejandra (1981). “La conquista espiritual”. En Historia general de México. México: El Colegio de México.Olavarría Ferrari, Enrique de (1953). “Pasión de Cristo”. En Enciclopedia de la religión católica [t. V]. Barcelona: Dalma y Jovier._____ (1961). Reseña del teatro en México. México: Porrúa.Pike E., Royston (1986). Diccionario de religiones. México: FCE.Prieto, Guillermo (1969). Memorias de mis tiempos. México: Patria.Rodríguez, Mariángela (1991). Hacia la estrella con la Pasión y la ciudad a cuestas. Semana Santa en Iztapalapa. México: Ediciones de la Casa Chata-CIESAS.Sociedad Bíblica Británica y Extranjera de Londres (1929). La Santa Biblia. Londres: SBBEL.Vetancurt, Agustín de (1941). Teatro mexicano: descripción breve de los sucesos exemplares de la Nueva España en el mundo occidental de las Indias. Madrid: J. Porrúa.Verti, Sebastián (1991). Tradiciones mexicanas. México: Diana.Weckmann, Luis (1984). La herencia medieval de México. México: FCE
The Viral Author
No full textLa idea moderna de la "figura de autor" debe mucho, de manera irreversible, a los dos ensayos de Roland Barthes y Michel Foucault, "La muerte del autor" y "¿Qué es un autor?". Ellos proporcionan un marco útil para una investigación sobre la aparente ausencia del autor en el mundo del web, nos permite preguntarnos si la autoría es congruente con los nuevos medios de comunicación, y si algún modelo puede ser establecido por su presencia. Se argumenta que el autor es de hecho presente, pero con su presencia y modalidades de actividad desplazadas a la figura del usuario.The modern idea of the author-figure owes much, irreversibly, to the two essays of Roland Barthes and Michel Foucault, “The Death of the Author” and “What is an Author?”. They provide a useful framework for an investigation into the apparent absence of the author-figure in the online world, allow us to ask whether authorship is congruent with online media, and whether some model may be established for his presence. It is argued that the author is indeed present, but with his presence and modes of activities displaced, perhaps counter-intuitively, to the figure of the user
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