1,301 research outputs found
Second harmonic generation at fatigue cracks by low-frequency Lamb waves: experimental and numerical studies
No full textAbstract not availableYi Yang, Ching-Tai Ng, Andrei Kotousov, Hoon Sohn, Hyung Jin Li
La crítica materialista de Sohn-Rethel o “No lo saben, pero lo hacen”
No full textEscribimos este trabajo como una breve presentación de algunos aspectos del pensamiento de Alfred Sohn-Rethel (1899-1990) que, aunque representa una de las apropiaciones más originales de Marx, es escasamente conocido en Latinoamérica. Aunque sus ideas fueron muy cercanas a las de los pensadores teóricos de la llamada Escuela de Frankfurt –en especial, Theodor Adorno y, en menor medida, Walter Benjamin–, nunca se insertó formalmente en el Instituto de Investigación Social. Igualmente, pudo alcanzar, por sus reconocidos aportes, un cargo universitario en Bremen, pero recién en su vejez. En primer lugar, comenzaremos por clarificar el peculiar sentido que Alfred Sohn-Rethel da al concepto de crítica. El subtítulo del libro, Crítica de la epistemología, reenvía a dos legados: el de la crítica materialista histórica de la economía política y el de la crítica kantiana del conocimiento. Reseñemos mínimamente el doble legado que habilita esta singular apropiación de la noción de Kritik por Sohn-Rethel.Fil: Martín, Facundo Nahuel. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Mariano NIcolás. Universidad de Buenos Aires; Argentin
Bayesian probabilistic damage detection of a reinforced-concrete bridge column
No full textA Bayesian probabilistic approach for damage detection has been proposed for the continuous monitoring of civil structures (Sohn H, Law KH. Bayesian probabilistic approach for structure damage detection. Earthquake Engineering and Structural Dynamics 1997; 26: 1259-1281). This paper describes the application of the Bayesian approach to predict the location of plastic hinge deformation using the experimental data obtained from the vibration tests of a reinforced-concrete bridge column. The column was statically pushed incrementally with lateral displacements until a plastic hinge is fully formed at the bottom portion of the column. Vibration tests were performed at different damage stages. The proposed damage detection method was able to locate the damaged region using a simplified analytical model and the modal parameters estimated from the vibration tests, although (1) only the first bending and first torsional modes were estimated from the experimental test data, (2) the locations where the accelerations were measured did not coincide with the degrees of freedom of the analytical model, and (3) there existed discrepancies between the undamaged test structure and the analytical model. The Bayesian framework was able to systematically update the damage probabilities when new test data became available. Better diagnosis was obtained by employing multiple data sets than just by using each test data set separately. Copyright (C) 2000 John Wiley & Sons, Ltd.The "rst author wishes to express his sincere thanks to Professor Gerard C. Pardoen and his students at the
University of California at Irvine for providing an opportunity to observe the bridge column test. Also, the
authors are indebted to Dr Charles R. Farrar and Dr Scott W. Doebling of the Los Alamos National
Laboratory for providing the vibration test data. This research was partially sponsored by the National
Science Foundation under Grant No. CMS-95261-2
Troca ou produção? Uma introdução crítica à proposta teórica de Alfred Sohn-Rethel
No full textThis paper explores and analyzes the critique of the modern-traditional epistemology of the philosopher Alfred Sohn-Rethel, focusing on the categories of "social synthesis" and "real abstraction" that the author postulated in his magnum opus Manual Work and Intellectual Work (2001) . Sohn-Rethel\u27s perspective seeks to critically adapt Marx\u27s materialist conception of history to the analysis of the emergence of the fundamental categories of scientific knowledge, as formulated in European modernity. However, the author\u27s emphasis on exchange over production ends up being inconsistent with basic postulates derived from the critique of political economy formulated by Marx in Capital. Thus, from the review of Marx\u27s categories and taking into account the position of other authors, the research emphasizes the limitations derived from the Sohn-Rethel proposal when analyzing the social forms of knowledge.El presente artículo explora y analiza la crítica a la epistemología moderna-tradicional del filósofo Alfred Sohn-Rethel centrándose en las categorías de “síntesis social” y “abstracción real” que el autor postuló en su obra magna Trabajo manual y trabajo intelectual (2001). La perspectiva de Sohn-Rethel busca adecuar críticamente la concepción materialista de la historia de Marx al análisis de la emergencia de las categorías fundamentales del conocimiento científico, tal y como se formularon en la modernidad europea. Sin embargo, el énfasis que el autor sostiene del intercambio por encima de la producción termina por ser incongruente con postulados básicos derivados de la crítica de la economía política formulada por Marx en El Capital. Así, a partir de la revisión de las categorías de Marx y tomando en cuenta la posición de otros autores, la investigación enfatiza en los limitantes derivados de la propuesta de Sohn-Rethel al analizar las formas sociales del conocimiento.Este artigo explora e analisa a crítica à epistemologia moderno-tradicional do filósofo Alfred Sohn-Rethel, com foco nas categorias de "síntese social" e "abstração real" que o autor postulou em sua magnum opus Trabalho Manual e Trabalho Intelectual (2001). ). A perspectiva de Sohn-Rethel procura adaptar criticamente a concepção materialista da história de Marx à análise da emergência das categorias fundamentais do conhecimento científico, tal como formuladas na modernidade europeia. No entanto, a ênfase do autor na troca sobre a produção acaba sendo inconsistente com os postulados básicos derivados da crítica da economia política formulada por Marx em O Capital. Assim, a partir da revisão das categorias de Marx e levando em conta a posição de outros autores, a pesquisa enfatiza as limitações derivadas da proposta de Sohn-Rethel ao analisar as formas sociais de conhecimento
Transient modeling of thermal degradation in non-charring solids
No full textFor a more extensive investigation of polymers, a better understanding of its gasification process is extremely essential. Especially compared with the extensive studies in the gas phase, the solid phase received rather little attention. Thus, the purpose of this paper is in its comparison of several modeling approaches for thermal degradation and systematic demonstration of the effects of basic assumptions on the model results, while taking account of in-depth radiation. For this object, this study has examined in more detail the degradation for a horizontally positioned polymer which is exposed to external radiation. After a preliminary study, three different solid degradation models were chosen from the literature, and their corresponding mass and energy conservation equations and boundary conditions were assembled. The in-depth non-gray as well as gray radiation was taken into account by solving relevant radiative transfer equation. In order to concentrate on the fundamental mechanisms of polymer degradation, gas phase reactions and subsequent heal feedback from the gas were neglected. This corresponds to a nitrogen environment. Various other parameters such as the polymer refractive index, polymer absorption coefficient, convective heat loss, solid fuel thickness and external radiative heat flux were changed to discuss their effects on the quantitative as well as qualitative change in the mass loss rate. While the effect of the solid fuel thickness on the mass loss rate was negligible for a thick sample, each parameter among the polymer refractive index, polymer absorption coefficient, convective heat loss, and external radiative heat flux incurred a non-negligible change in the results. Furthermore, the convection term in the energy equation, which is usually neglected in the in-depth pyrolysis by many other works, was shown to account for 29% decrease in the mass loss rate. Finally, depending on the solid degradation model used, the addition of gray radiation to the energy equation was shown to augment or diminish the mass loss rate. It was further enhanced by taking account of the non-gray radiation. This results from the fact that the inner solid is more quickly heated due to the far-reaching effects of radiation from the surface
Disparity estimation using a region-dividing technique and energy-based regularization
No full textA two-stage algorithm is proposed for locating smooth and detailed disparity vector fields in a stereo image pair. The algorithm consists of hierarchical disparity estimation using a region-dividing technique and edge-preserving regularization. The hierarchical region-dividing disparity estimation increases the efficiency and reliability of the estimation process. At the second stage, the vector fields are regularized with an energy model that produces smooth fields while preserving discontinuities resulting from object boundaries. The minimization problem is addressed by solving a corresponding partial differential equation using a finite-difference method. Experiments show that the proposed algorithm provides accurate and spatially correlated dispartly vector fields in various types of stereo images, even in the case of images with large displacements. © 2004 Society of Photo-Optical Instrumentation Engineers
Teodolito
No full textLa fecha de producción se ha tomado de fuentes directas existentes en el Archivo del Observatorio de San Fernando.Sumario: El teodolito Ertel & Sohn es uno de los llamados teodolitos sencillos (plain theodolite), caracterizados por no disponer de círculo graduado vertical completo. Se trata, pues, de un instrumento utilizado para la medida de los ángulos horizontales y para trabajos de nivelación geodésica. Va dotado de montura acimutal, con círculo horizontal graduado y sector vertical graduado 50º -0º -50º.
Fue construido por la casa alemana Ertel & Sohn, fundada por T. L. Ertel y su hijo Georg en 1834. Llegó al Observatorio con destino a la Comisión Hidrográfica de las Antillas. Estuvo a cargo de la Comisión encargada de la observación del paso de Venus de 1882, de las fragatas Blanca y Carmen (1885-1889), y de la Comisión Hidrográfica de las Antillas (1890-1899).Transcripción: "Ertel & Sohn in Munchen
Baseline-free damage detection through mode separation of lamb waves using self-sensing piezoelectric wafer transducers
No full textThis research is supported by the Radiation Technology Program under Korea
Science and Engineering Foundation (KOSEF) and the Ministry of Science and
Technology (M20703000015-07N0300-01510) and Korea Research Foundation
(D00462)
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