Inverse mass matrix via the method of localized lagrange multipliers

An efficient method for generating the mass matrix inverse is presented, which can be tailored to improve the accuracy of target frequency ranges and/or wave contents. The present method bypasses the use of biorthogonal construction of a kernel inverse mass matrix that requires special procedures for boundary conditions and free edges or surfaces, and constructs the free-free inverse mass matrix employing the standard FEM procedure. The various boundary conditions are realized by the method of localized Lagrange multipliers. Numerical experiments with the proposed inverse mass matrix method are carried out to validate the effectiveness proposed technique when applied to vibration analysis of bars and beams. A perfect agreement is found between the exact inverse of the mass matrix and its direct inverse computed through biorthogonal basis functions

The social learning of threat and safety in the family:Parent-to-child transmission of social fears via verbal information

Parental verbal threat (vs. safety) information regarding the social world may impact a child's fear responses, evident in subjective, behavioral, cognitive, and physiological indices of fear. In this study, primary caregivers provided standardized verbal threat or safety information to their child (N = 68, M = 5.27 years; 34 girls) regarding two strangers in the lab. Following this manipulation, children reported fear beliefs for each stranger. Physiological and behavioral reactions were recorded as children engaged with the two strangers (who were blind to their characterization) in a social interaction task. Child attention to the strangers was measured in a visual search task. Parents also reported their own, and their child's, social anxiety symptoms. Children reported more fear for the stranger paired with threat information, but no significant differences were found in observed child fear, attention, or heart rate. Higher social anxiety symptoms on the side of the parents and the children exacerbated the effect of parental verbal threat on observed fear. Our findings reveal a causal influence of parental verbal threat information only for child‐reported fear and highlight the need to further refine the conditions under which acquired fear beliefs persist and generalize to behavior/physiology or get overruled by nonaversive real‐life encounters

Stand dynamics, spatial pattern and site quality in Austrocedrus chilensis forests in Patagonia, Argentina

Aim of study: The objective of this study was to analyze the stand structure and spatial pattern of two A. chilensis stands with contrasting soil conditions and different site qualities in order to explore if these differences lead to patterns similar to the ones observed under different precipitation conditions.Area of study: The study was carried out in two stands located near the city of El Bolsón (41° 56’S - 71° 33’ W), Rio Negro, Argentina.Material and Methods: We evaluated age difference between canopy strata (upper and lower) in two stands with different site qualities by means of a Mann-Whitney test. Dead individuals by diameter class were compared by means of a chi square test. Spatial distribution pattern was analyzed using the pair-correlation function and the mark-correlation function.Main results: Both sites exhibited a random spatial distribution of A. chilensis but different processes seem to underlie the patterns. In the low-quality site facilitation and continuous establishment led to a transient clumped spatial pattern. Mortality mediated by competition occurred mainly on small trees resulting in the current random pattern. On the other hand, spatial pattern in the high-quality site does not reflect a facilitation mediated recruitment. The upper strata established synchronously and subsequent regeneration was episodic.Research highlights: The results show that the differences in site quality may lead to different establishment spatial patterns, showing the importance of facilitation processes in sites with drier soil conditions and lower quality, although results may be site specific, due to the lack of replications.Keywords: Spatial analysis; regeneration; mortality; competition; facilitation.Abbreviations used:  LQ: low-quality site; HQ: high-quality site

Corrección de la deriva en sistemas de seguimiento solar a través de control de lazo cerrado

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: Los sistemas de seguimiento solar de dos ejes en aplicaciones de concentración solar requieren una mayor precisión en el seguimiento automático de la posición aparente del Sol, esto con el fin de mantener la radiación solar concentrada en una posición fija en el receptor del sistema, ya que una mínima variación se traduce en un desplazamiento (deriva) del spot de concentración de la zona de interés. Este trabajo se centra en la discusión de los métodos implementados para la solución de los problemas de deriva y corrección de los ángulos de elevación y acimut en los dispositivos de seguimiento solar. Para llevar a cabo la evaluación de la corrección de la deriva, se emplearon dos dispositivos de seguimiento solar de dos ejes de movimiento. Un Helióstato de 36 m2 (E3) ubicado en la Plataforma Solar de Hermosillo, Sonora, México. El segundo es un concentrador solar reflectivo de no imagen tipo Fresnel para la caracterización de celdas fotovoltaicas ubicado en el IER-UNAM en Temixco, Morelos, México. El análisis planteado en este documento se basa principalmente en la comparativa de los resultados obtenidos a partir de implementar una estrategia de control de lazo abierto y cerrado. El control de lazo abierto consiste en un código de programación que realiza el cálculo de la posición del Sol mediante algoritmos propuestos por distintos autores, y que permiten enviar señales de comando a los actuadores de los ejes de acimut y elevación en ambos dispositivos de seguimiento. Para la metodología de lazo cerrado se utiliza un sistema óptico de retroalimentación que trata de un dispositivo de visión (CCD) que permite observar la posición del Sol en tiempo real.ABSTRACT: Two axis solar tracking systems require high precision regarding automatic tracking of apparent sun position for solar concentration applications. This, with the aim of maintaining the concentrated solar radiation in a fixed position in the system´s receiver. This is so, because a minimum variation results in a deviation (drift) of the solar image concentrated in the area of interest. This work focuses on a discussion of implemented methods for solving drift problems and a correction of elevation and azimuth angles in solar tracking devices. Two sun tracking devices of two axes movement were used in order to evaluate drift correction. The first one was a 36 m2 heliostat (named E3), located in the Solar Platform in Hermosillo, Sonora, México. The second tracking device was a solar concentrator Fresnel type for characterizing photovoltaic cells (FRESNEL) located at IER-UNAM, Temixco, Morelos, México. The analysis of this document is mainly based on the comparison of obtained results from implementing an open-loop and close-loop control strategy. Open-loop control consists of a program code that calculates the Sun's position using algorithms suggested by different authors, it allows send command signals to elevation and azimuth axis actuators on both tracking devices. Closed-loop methodology uses an optical feedback system, which refers to a vision device (webcam) that allows observing in real time the Sun´s position.info:eu-repo/semantics/publishedVersio

Resurrección, apocalíptica, historia. Emergencia y desarrollo de la idea de resurrección en el judaísmo del II Templo

Esta tesis doctoral explora la temática del origen de la creencia en la resurrección de los muertos en el judaísmo del II Templo mediante el análisis de las concepciones fundamentales de la apocalíptica. Consiste en un examen del contexto histórico y sociológico en el que surgió el movimiento apocalíptico, así como de la impronta de la teología bíblica, del helenismo y de las religiones circundantes, y del modo en que su imagen del mundo, de la humanidad y de la historia configuró sus creencias escatológicas. Siguiendo a la clasificación de las principales tendencias en la investigación contemporánea aparece un tratamiento sistemático de la teología apocalíptica, y un estudio de los textos bíblicos e intertestamentarios más importantes. Esta tesis aborda los distintos niveles de significación adoptados por la idea de resurrección en la teología apocalíptica, prestando especial atención a la respuesta al problema de la teodicea y a su potencial crítico y emancipador con respecto a la realidad presente. La conclusión más relevante se refiere al influjo de la visión cosmopolita y universalista de la historia, propiciada por el helenismo, en el nacimiento de una perspectiva menos etnocéntrica, que habría favorecido la asimilación de una proyección escatológica de la acción divina al final de los tiempos, subrayando el destino común de la humanidad más que el de la nación (restauración colectiva). El énfasis en la pertenencia a la nación se sustituye por la fe en un juicio universal que afectará a todos los seres humanos

Inverse mass matrix via the method of localized Lagrange multipliers

An efficient method for generating the mass matrix inverse of structural dynamic problems is presented, which can be tailored to improve the accuracy of target frequency ranges and/or wave contents. The present method bypasses the use of biorthogonal construction of a kernel inverse mass matrix that requires special procedures for boundary conditions and free edges or surfaces and constructs the free-free inverse mass matrix using the standard FEM procedure. The various boundary conditions are realized by the the method of localized Lagrange multipliers. In particular, the present paper constructs the kernel inverse matrix by using the standard FEM elemental mass matrices. It is shown that the accuracy of the present inverse mass matrix is almost identical to that of a conventional consistent mass matrix or a combination of lumped and consistent mass matrices. Numerical experiments with the proposed inverse mass matrix are conducted to validate its effectiveness when applied to vibration analysis of bars, beams, and plain stress problems.Centre of Excellence for nonlinear dynamic behavior of advanced materialsin engineering CZ.02.1.01/0.0/0.0/15 003/000049