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Non-Linear Geometric Analysis in Guyed Masts No linealidad geométrica en torres atirantadas
Vivian Elena Parnás,Ingrid Fernández Lorenzo
Revista Cubana de Ingeniería , 2011, DOI: 10.1234/rci.v2i3.56
Abstract: A guyed mast is an example of structures with non-lineal behaviour under extreme wind loads. Cables are used to stabilize structures; changes in the stiffness of these structures give rise to non linearity. The variations in stiffness are produced as results of displacements of structures under wind loads and of variations in tension in cables. The aim of this paper is to analyse the variations obtained in internal stresses in tower members under extreme wind loads by considering and not considering the geometric non-linearity alternatively in order to value the necessity of non-lineal geometric application in guyed mast under extreme wind loads. Results obtained from the guyed mast model reflect considerable increases in stress in all members of the tower under non-linear analysis compared to linear analysis and confirm that linear analysis conduces to increases in vulnerability under wind loads and hence to an unsafe design. Las torres atirantadas son estructuras con un alto comportamiento estructural no lineal geométrico bajo la acción de cargas de viento extremas. La no linealidad es debida a los cambios en la rigidez que experimentan los cables que las estabilizan, lo cual se produce a partir de los desplazamientos de la estructura bajo cargas de dise o y la consecuente variación de tensión en los cables. Los cables a barlovento incrementan los valores de tensión mientras que los cables a sotavento experimentan distensión. Este trabajo tiene por objeto estudiar las variaciones en los esfuerzos internos obtenidos en los elementos de una torre atirantada bajo carga de viento extrema considerando la no linealidad geométrica y sin considerarla, a fin de valorar la necesidad de este tipo de análisis. Los resultados obtenidos de la modelación de la torre reflejaron incrementos significativos en los esfuerzos para todos los elementos, confirmando la necesidad de aplicación de análisis no lineal en torres bajo carga de viento extrema. Los resultados permiten afirmar que la no consideración de la no linealidad geométrica produce un au
El movimiento de los trabajadores rurales sin tierra y la reforma agraria en Brasil
Lorenzo FERNáNDEZ FRANCO
América Latina Hoy , 2009,
Abstract: RESUMEN: Este artículo, es un primer avance, de carácter exploratorio, de una investigación más amplia que el autor está llevando a cabo sobre el mismo tema. Centrado en el "Movimiento de los Trabajadores Rurales sin Tierra", habitualmente identificado en Brasil por las siglas MST, se contempla dicho movimiento social desde sus orígenes más remotos, al final de los a os 50, hasta nuestros días situándolo, por un lado, en las transformaciones políticas y en parte sociales, y en el largo y lento proceso de una reforma agraria inconclusa, por otro. De forma descriptiva, se desarrollan, en un primer paso, los antecedentes, proceso de constitución, etapas y estructura agraria brasile a, se plantea de forma suscinta la problemática de la reforma agraria. Con estas consideraciones preliminares, siguiendo casi literalmente la formulación del propio MST, se exponen, con mayor amplitud, los objetivos y características de la Reforma Agraria desde la perspectiva de los propios trabajadores rurales. Asimismo, aunque de forma más esquemática y en base a los datos oficiales, se plantean las directrices, metas y algunas de las realizaciones del Gobierno de Fernando H. Cardoso sobre dicha reforma. En definitiva, con este artículo, se pretenden establecer las bases y los ejes analíticos necesarios para una investigación más amplia y comprensiva de este fenómeno social de masas que va más allá de la propia realidad de injusticia que se está viviendo en el mundo rural brasile o y que está contando también con un amplio y sorprendente apoyo de sectores urbanos de la población brasile a. ABSTRACT: This article is an introductory and exploratory advance of a more extensive investigation that the author is carrying out on the same subject. The research is centred on the "Movement of the Rural Workers without Land", which is ussually identified in Brazil with the initials MST. This social movement is analyzed since its remotest origins, the end of the fifties to present day, contextualizing the political and social transformations and the long, slow process of an unfinished agrarian reform. In a descriptive way, the study develops at first the backgrounds, constitutional process, phases and organizational structure of the MST and after some brief comments on the Brazilian agricultural structure, it moves on to the problematic agriculture reform. With these preliminary considerations, following almost literally the formulation of the own MST, the investigation displays, to a greater extent, the objectives and characteristics of the agricultural reform from the point of view of t
ANáLISIS Y RESULTADOS DE UN MODELO DE EVALUACIóN, APOYO Y MEJORA DE PROYECTOS EMPRESARIALES IMPULSADOS POR JóVENES EMPRENDEDORES
REVUELTO TABOADA,LORENZO; FERNáNDEZ GUERRERO,RAFAEL;
Estudios Gerenciales , 2009,
Abstract: analysis and results of a model to assess, support, and improve business projects run by young entrepreneurs new firms play an important role in employment, economic growth, innovation, and competitiveness. for this reason, a growing number of public institutions are dedicating more and more resources to promoting entrepreneurship. thus, it is particularly interesting to analyze the effectiveness of different programs and identify the most effective practices. the main objective of this paper is to make progress in the improvement of systems used for assessing public assistance plans and show how changes introduced as a result of this assessment have important effects on the quality of start-ups. to accomplish this objective, we carried out an in-depth case study of the young entrepreneurs' assistance program launched by the valencian institute for youth.
New tools and new ideas for HR practitioners. Structural and predictive validity of weighted satisfaction questionnaire
Revuelto Taboada,Lorenzo; Fernández Guerrero,Rafael;
Cuadernos de Administración (Universidad del Valle) , 2012,
Abstract: one of the fundamental tasks for an human resource management (hrm) practitioner consists in designing a reward system that can be broadly understood and can influence the attitudes and, subsequently, the behavior of individuals to permit achievement of organizational objectives. to do so, appropriate tools are necessary to allow key actions to be identified in terms of motivating employees; thereby, avoiding opportunistic costs derived from allocating resources needed to close the gap in employee satisfaction, with regard to non-priority factors for workers in satisfying their own personal needs. this article, thus, presents a dual assessment scale consisting of 44 items, categorized into six dimensions, which firstly evaluates the importance of motivation and, secondly, the level of satisfaction with the current situation for each of the 44 factors considered. using a sample of 801 individuals, we analyzedthe internal consistency, face validity, and predictive validity of the measuring scales, obtaining a series of results that were, to say the least, promising
Dos nuevas obras de Francisco Gallardo
Alonso de la Sierra Fernández, Lorenzo
Archivo Espa?ol de Arte , 2001,
Abstract: La localización de dos lienzos firmados por Francisco Gallardo, uno en Sevilla y otro en Cádiz, amplía las escasas noticias que se conocen sobre la vida y obra de este autor. El cuadro de Cádiz, de propiedad particular, es un trampantojo del tipo conocido como rincón de taller y sus dimensiones son 83 x 62 cms. En él destaca una estampa, sobre la que se posa una mosca, clavada al habitual fondo de tablas, y en cuya zona inferior se puede leer: En Cádiz, a o de 1720... Franco. Julo. Gallado F. . Bajo la estampa hay una cinta, sujeta con puntas y atravesada en uno de los extremos por un punzón, que sirve de soporte a una carta plegada en la cual aparece escrito: Sr. Dn. Franco X... . La obra conservada en Sevilla, también de propiedad particular, mide 157 x 108 cms. y representa a santo Tomás de Aquino.…
ANáLISIS Y RESULTADOS DE UN MODELO DE EVALUACIóN, APOYO Y MEJORA DE PROYECTOS EMPRESARIALES IMPULSADOS POR JóVENES EMPRENDEDORES
LORENZO REVUELTO TABOADA,RAFAEL FERNáNDEZ GUERRERO
Estudios Gerenciales , 2009,
Abstract: Las empresas de nueva creación juegan un papel crucial en la generación de empleo, el crecimiento económico, la innovación y la competitividad. Ello ha llevado a un número creciente de instituciones públicas a dedicar ingentes recursos al apoyo y fomento de iniciativas empresariales. Resulta por ello de especial interés analizar la eficacia de los distintos programas e identificar cuáles son las prácticas más efectivas. Este trabajo tiene como objetivo avanzar en la mejora de los sistemas de evaluación de programas de ayuda a emprendedores y mostrar cómo las mejoras introducidas pueden tener efectos sobre la calidad de los negocios creados. Para ello se analiza en profundidad el caso del programa de ayudas a jóvenes emprendedores del Instituto Valenciano de la Juventud.
Determination of vanadium accumulation in onion root cells (Allium cep a L.) and its correlation with toxicity
Letty Marcano,Ingrid Carruyo,Yusmary Fernández,Xiomara Montiel
Biocell , 2006,
Abstract: The vanadium is a metal that presents great interest from the toxicological point of view, because of the numerous alterations that can take place in different biological systems. This work evaluated the capacity of vanadium accumulation and its correlation with genotoxic effects in root cells of Allium cepa L. The bulbs were cultivated in renovated filtered water each 24 h, at a temperature of 25 ± 0.5 ° C, in darkness and constant aeration. Treatments were carried out under the same experimental conditions, using water solutions of vanadium of 25, 50, 75 and 100 μ g/g for 0, 12, 24, 48 and 72 h. A control was carried out where metal solution was substituted by distilled water. After the treatment, the meristems were fixed with alcohol - acetic acid (3:1) and stained according to the technique of Feulgen. The capacity of accumulation was determined by GFAAS. The analysis of the results revealed an accumulation of the metal for all times and concentrations. No correlation was presented among vanadium accumulation, growth and mitotic index; however, positive correlation was given with the induction of chromosomic aberrations. In conclusion, vanadium is able to induce cytotoxic effect in the exposed roots, but only genotoxic effect was correlated with metal accumulation.
Tipificación fágica de aislados de Salmonella enteritidis de muestras clínicas, alimentarias y avícolas en Chile
Prat,Soledad; Fernández,Alda; Fica,Alberto; Fernández,Jorge; Alexandre,Marcela; Heitmann,Ingrid;
Revista Panamericana de Salud Pública , 2001, DOI: 10.1590/S1020-49892001000100004
Abstract: since 1994 an extensive epidemic of infections with salmonella enteritidis (s. enteritidis) has affected chile. in order to understand the diversity of infective sources, the possible origin of the epidemic, and the epidemiological relationships between clinical, food, and poultry isolates, we carried out phage typing of three groups of samples: 1) 310 s. enteritidis clinical samples collected between 1975 and 1996, 2) 47 food isolates obtained during s. enteritidis outbreaks, and 3) 27 strains isolated in surveillance studies of poultry-raising establishments. with the clinical samples, a total of 13 phage types were identified, 2 isolates could not be typed, and 1 was considered atypical. the phage types that were identified most frequently were 1 (56.8%) and 4 (31.3%), trailed by type 8 (4.8%) and type 28 (1.9%). over time and in different regions of the country there were major changes in the distribution of the phage types. in the first years of collection the only phage types registered were 8 and 28, which disappeared around 1980 and then began reappearing sporadically in 1996. with the gradual s. enteritidis expansion that started in 1988, in the central and southern areas of the country phage type 4 began to appear; that type had not been found before in chile. in 1991 in the northern area of the country phage type 1 began to predominate; it was another type that had not been reported before in chile. in the food isolates the only phage types identified were 1 and 4, which were also the most common in the poultry isolates. phage typing of s. enteritidis has proved to be useful in guiding the epidemiological analysis of the infections caused by this pathogen.
Map Building and Monte Carlo Localization Using Global Appearance of Omnidirectional Images
Luis Payá,Lorenzo Fernández,Arturo Gil,Oscar Reinoso
Sensors , 2010, DOI: 10.3390/s101211468
Abstract: In this paper we deal with the problem of map building and localization of a mobile robot in an environment using the information provided by an omnidirectional vision sensor that is mounted on the robot. Our main objective consists of studying the feasibility of the techniques based in the global appearance of a set of omnidirectional images captured by this vision sensor to solve this problem. First, we study how to describe globally the visual information so that it represents correctly locations and the geometrical relationships between these locations. Then, we integrate this information using an approach based on a spring-mass-damper model, to create a topological map of the environment. Once the map is built, we propose the use of a Monte Carlo localization approach to estimate the most probable pose of the vision system and its trajectory within the map. We perform a comparison in terms of computational cost and error in localization. The experimental results we present have been obtained with real indoor omnidirectional images.
Experiencia en la Aplicación del Aprendizaje Basado en Problemas en la Asignatura Proyecto de Licenciatura en Química
Lorenzo,Rosa A; Fernández,Purificación; Carro,Antonia M;
Formación universitaria , 2011, DOI: 10.4067/S0718-50062011000200005
Abstract: the design and implementation of a virtual classroom on the webct platform for the course chemistry project at the university of santiago de compostela in spain are described. problem-based learning has been implemented in this course. the topic of the course belongs to the experimental training block and its objective is to provide the student of an initial formation in scientific experimental research through a supervised work proposed by the instructors. the application of the methodology of problem-based learning has proved to be a very useful experience for the development of skills, abilities and competences, nowadays demanded by companies and institutions.
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