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Search Results: 1 - 10 of 15 matches for " Lombera "
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Proporción y autoría. Arte mueble paleolítico. Figuras de los Omóplatos de
José Antonio Fernández Lombera
Munibe Antropologia-Arkeologia , 2003,
Abstract: El trabajo se compone de las siguientes partes : a.- Realización de calcos con una gran objetividad gráfica de las figuras grabadas en los omóplatos de El Castillo, exhumados por OBERMAIER en sus campa as de 1911/12. b.- Dise o, validación y aplicación de un método para el cálculo de la proporción de una figura, independoentemente de cuál sea, enfrentándola a un arquetipo. c.- Aplicación de tal método, una vez validado, a las figuras de los omóplatos de El Castillo. d.- Análisis de la manera de hacer de cada uno de los autores de las figuras de El Castillo ; es a lo que llamamos autoría. e.- Obtención de un conjunto de conclusiones de tipo formal, artístico y paleoetnológico
Modelado numérico del proceso de pultrusión en materiales compuestos
Santiago, Diego;Lombera, Guillermo;Urquiza, Santiago;Moschiar, Stella M.;
Materials Research , 2003, DOI: 10.1590/S1516-14392003000400027
Abstract: a mathematical pultrusion model of a thermosetting matrix composite is presented. the energy balance was solved by finite elements techniques using a program developed for this purpose. this model is applied to describe the temperature and resin conversion profiles along the die. this study was developed considering different pulling velocity, die temperature, different composite and different sections die. the model outcomes are verified through comparison with the experimental results reported in the literature.
New records of Heliconia (Heliconiaceae) for the region of Chajul, Southern Mexico, and their potential use in biodiversity-friendly cropping systems
Santos, Bráulio A.;Lombera, Rafael;Benitez-Malvido, Julieta;
Revista mexicana de biodiversidad , 2009,
Abstract: we report 4 new records of heliconia species (heliconiaceae) for the region of chajul, one of the most studied sites of the mexican lacandona. records are for h. champneiana griggs cv. maya gold, h. latispatha bentham cv. orange gyro, h. vaginalis bentham, and h. wagneriana petersen. we provide a brief description of morphological and ecological traits of the species and demonstrate the high potential they have to be cultivated in biodiversity-friendly cropping systems. we suggest the use of heliconia in the enrichment of secondary forests and forest fragments as an alternative of combining forest management with biological conservation.
3D modeling of material flow and temperature in Friction Stir Welding
Santiago, Diego;Urquiza, Santiago;Lombera, Guillermo;Vedia, Luis de;
Soldagem & Inspe??o , 2009, DOI: 10.1590/S0104-92242009000300008
Abstract: the process of friction stir welding (fsw) is a welding method developed by the "the welding institute" (twi) of england in 1991. the welding equipment consists of a tool that rotates and progresses along the joint of two restrained sheets. the joint is produced by frictional heating which causes the softening of both components into a viscous-plastic condition and also by the resultant flow between the sheets to be joined. numerical modeling of the process can provide realistic prediction of the main variables of the process, reducing the number of experimental tests, thus accelerating the design processes while reducing costs and optimizing the involved technological variables. in this study the friction stir welding process is modeled using a general purpose finite element based program, reproducing the material thermal map and the corresponding mass flow. numerical thermal results are compared against experimental thermographic maps and numerical material flow results are compared with material flow visualization techniques, with acceptable concordance.
Modelado numérico del proceso de pultrusión en materiales compuestos
Santiago Diego,Lombera Guillermo,Urquiza Santiago,Moschiar Stella M.
Materials Research , 2003,
Abstract: A mathematical pultrusion model of a thermosetting matrix composite is presented. The energy balance was solved by Finite Elements techniques using a program developed for this purpose. This model is applied to describe the temperature and resin conversion profiles along the die. This study was developed considering different pulling velocity, die temperature, different composite and different sections die. The model outcomes are verified through comparison with the experimental results reported in the literature.
New records of Heliconia (Heliconiaceae) for the region of Chajul, Southern Mexico, and their potential use in biodiversity-friendly cropping systems Nuevos registros de Heliconia (Heliconiaceae) para la región de Chajul, sur de México, y su uso potencial en plantaciones amigables de la biodiversidad
Bráulio A. Santos,Rafael Lombera,Julieta Benitez-Malvido
Revista mexicana de biodiversidad , 2009,
Abstract: We report 4 new records of Heliconia species (Heliconiaceae) for the region of Chajul, one of the most studied sites of the Mexican Lacandona. Records are for H. champneiana Griggs cv. Maya Gold, H. latispatha Bentham cv. Orange Gyro, H. vaginalis Bentham, and H. wagneriana Petersen. We provide a brief description of morphological and ecological traits of the species and demonstrate the high potential they have to be cultivated in biodiversity-friendly cropping systems. We suggest the use of Heliconia in the enrichment of secondary forests and forest fragments as an alternative of combining forest management with biological conservation. Se registran por primera vez 4 especies de Heliconia (Heliconiaceae) para la región de Chajul, uno de los sitios más estudiados de la lacandona mexicana. Los nuevos registros son para H. champneiana Griggs cv. Maya Gold, H. latispatha Bentham cv. Orange Gyro, H. vaginalis Bentham, y H. wagneriana Petersen. Se presenta una breve descripción acerca de las características morfológicas y ecológicas de las especies y se demuestra el alto potencial que tienen para ser cultivadas en plantaciones amigables de la biodiversidad. Se sugiere el uso de Heliconia en el enriquecimiento de bosques secundarios y fragmentos de selva como una alternativa de combinar manejo forestal con conservación biológica.
Numerical modeling of welded joints by the "Friction Stir Welding" process
Santiago, Diego H.;Lombera, Guillermo;Urquiza, Santiago;Cassanelli, Anibal;Vedia, Luis A. de;
Materials Research , 2004, DOI: 10.1590/S1516-14392004000400010
Abstract: the present work is aimed to simulate the friction stir welding process as a three-dimensional thermally coupled viscoplastic flow. a finite element technique is employed, within the context of a general purpose fem framework, to provide the temperature distributions and the patterns of plastic flow for the material involved in the welded joints. the computational tool presented here may be of great relevance for technologist seeking to set the process control variables, as they are intended to obtain suitable material properties that yield the adequate on service response of the structural components.
Modelado numérico del socavado lateral en procesos de soldadura
Cassanelli, A.;Márquez, A.;Lombera, G.;De Vedia, L.A.;
Materials Research , 2003, DOI: 10.1590/S1516-14392003000100016
Abstract: when welded joints have to meet particular requirements related to fatigue life they are usually designed using the so called s-n design curves. this implies the construction of a curve for each particular design. from the point of view of the user, it is often difficult to establish accurately which is the curve that better fits the design that is being considered. the so called " local approach " is based on the concept that the fatigue strenght of welded joints is essentially determined by the local stress and strain in the " hot spots ". these spots are located in the geometric discontinuities of the joint. through this approach is possible to consider the possibility of constructing and using only one curve of design or " key curve ", for a given material. in this case the design parameter is the local stress or strain instead of the nominal stress. in the present work the lateral defect is modeled with fillet welds using the local approach combined with the finite elements method. a data base of kt for different dimensionless geometric relations is generated, and from these results an analytical function for the value of the concentrator is interpolated. finally the contour plots that were generated help reducing the number laboratory tests needed for the determination of kt.
Modelado numérico del proceso de soldadura por fricción agitación en aceros inoxidables
Pereyra, S.;Lombera, G.;Urquiza, S.;Santiago, D.;De Vedia, L.A.;
Matéria (Rio de Janeiro) , 2008, DOI: 10.1590/S1517-70762008000200017
Abstract: in this work the friction stir welding (fsw) process of stainless steel probes is modeled by a general propose finite element program, reproducing both thermal and material flow distribution. in the fsw process the equipment consist essentially of a rotating tool, which travel along the joint of two restricted plates. the union results from the frictional heating induced by the tool, which led into a viscoplastic material flow between the joined plates. this work simulates the process for a union of austenitic stainless steel considering thermo-mechanical coupling. in order to solve the mechanical problem, a viscoplastic model is implemented for this steel, involving a representative constitutive relation within the range of process temperatures. on the other hand, the related thermal problem is modeled considering the advection phenomena induced by the tool movement. at this first stage, the results obtained have been contrasted with data reported in the published literature, obtaining good agreement between them.
Discovering Joining Nodes and Detecting Leaving Nodes in the iTrust Membership Protocol
Yung-Ting Chuang,P. M. Melliar-Smith,L. E. Moser,Isai Michel Lombera
Lecture Notes in Engineering and Computer Science , 2013,
Abstract:
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