Fiber optic sensing system

A fiber optic interferometer utilizes a low coherence light emitting diode (LED) laser as a light source which is filtered and driven at two RF frequencies, high and low, that are specific to the initial length of the resonator chamber. A displacement of a reflecting mirror changes the length traveled by the nonreferencing signal. The low frequency light undergoes destructive interference which reduces the average intensity of the wave while the high frequency light undergoes constructive interference which increases the average intensity of the wave. The ratio of these two intensity measurements is proportional to the displacement incurred

Time domain referencing in intensity modulation fiber optic sensing systems

Intensity modulation sensors are classified depending on the way in which the reference and signal channels are separated: in space, wavelength (frequency), or time domains. To implement the time domain referencing different types of fiber optic (FO) loops have been used. A pulse of short duration sent into the loop results in a series of pulses of different amplitudes. The information about the measured parameter is retrieved from the relative amplitudes of pulses in the same train

Referencing in fiber optic sensing systems

Different techniques to account for losses induced by the environment on signals in intensity modulation fiber optic sensing systems are described and analyzed

RF modulated fiber optic sensing systems and their applications

A fiber optic sensing system with an intensity sensor and a Radio Frequency (RF) modulated source was shown to have sensitivity and resolution much higher than a comparable system employing low modulating frequencies or DC mode of operation. Also the RF modulation with an appropriate configuration of the sensing system provides compensation for the unwanted intensity losses. The basic principles and applications of a fiber optic sensing system employing an RF modulated source are described. In addition the paper discusses various configurations of the system itself, its components, and modulation and detection schemes. Experimental data are also presented

Fiber optic sensing systems using high frequency resonant sensing heads with intensity sensors

Optical fibers have an inherent capability of transmitting high bandwidth analog and digital signals. To apply this property of fiber optics to remote sensing, special sensing heads as well as signal processing electronics have to be developed. In systems employing intensity modulating sensors, there is also a need for a referencing technique to compensate for changes in the transmission of the connecting fibers and light source intensity. Fiber optic sensing systems incorporated in sensing heads of a special configuration are discussed. Different modes of operation as well as resonant conditions are explained. Theoretical and experimental analyses are also given

La revolución rusa de 1905 : el año en que nacieron los soviets

Fil: Adamovsky, Ezequiel. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina.En enero de 1905, se desató en Rusia un proceso revolucionario que se inició a partir del Domingo\nSangriento, cuando fuerzas represivas dispararon sobre una manifestación obrera pacífica que arrojó\ncomo resultado más de doscientos muertos. La miseria y el autoritarismo se tradujeron durante este\nlargo proceso en el pedido de libertades civiles, jornada de ocho horas, y el establecimiento de una\nrepública democrática. Si bien aquella revolución no tuvo éxito, subsistieron los soviets, los consejos\nde obreros fabriles destinados a canalizar las inquietudes de las bases y que se transformarían en el\nparadigma fundamental de la lucha revolucionaria, no sólo en Rusia sino en buena parte del mundo

Fiber optic sensors with internal referencing

The main problem with amplitude modulating type sensors is that any variation in the intensity of the optical signal which occurs throughout the sensing system is interpreted by the photodetector as resulting from the sensor itself and is reflected as an error in the sensed parameter. To account for these errors, a referencing technique with the signal and reference channels separated in the time domain over the same fiber link can be used. Selected sensing and signal processing techniques involving temporally separated signal and referencing channels are described. A transition from the time into the frequency domain is also discussed. Experimental data are presented

"Clase media": reflexiones sobre los (malos) usos académicos de una categoría

Para gobiernos, organismos internacionales y muchos académicos, una suerte de «clasemediarización» global sería la variable explicativa de muchos fenómenos actuales, y los propios actores suelen sentirse cómodos con esta categoría que remite a un políticamente correcto «justo medio», además de estar asociada a la modernidad y colocada en el mapa de la «civilización». Pero ¿qué es la clase media? ¿Se trata de un concepto científico o de un eslogan político? ¿Cómo usar esta categoría en la investigación política y social? Estas son algunas de las preguntas que este artículo se propone responder partiendo de una problematización del concepto que permite correrlo del sentido común dominante.Fil: Adamovsky, Ezequiel Agustin. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

N.F. Danielsón en la historia del pensamiento político ruso: los comienzos olvidados de una reflexión marxista sobre el atraso económico

En el presente artículo intentaremos rescatar del olvido la obra de N. F. Danielsón como una notable anticipación de las teorías acerca del atraso económico que sólo aparecerían muchos años más tarde. Al mismo tiempo, intentaremos una caracterización alternativa de sus ideas, en el contexto de los combates ideológicos del último cuarto del siglo XIX en Rusia.Fil: Adamovsky, Ezequiel Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto de Historia Argentina y Americana ; Argentin

Pierre Bezukhov Becomes (Really) Russian: Some Issues of National Identity in Tolstoy’s Narrative and Life Experience

This article seeks to analyze the weight and effects of the Western gaze (France’s in particular) in Tolstoy’s own life experience, and how it affected his literary production. The psychology of stigma provides some interesting insights as to how French opinions about Russia may have affected Tolstoy’s identity as a Russian, thus conditioning his choice of “identities” for the characters of some of his novels (for example, that of Pierre Bezukhov in War and Peace).Esse artigo procura analisar o peso e os efeitos do olhar ocidental (o francês, em particular) na experiência de vida de Tolstói, e como sua produção literária foi afetada. A psicologia do estigma fornece alguns insights interessantes sobre como as opiniões francesas a respeito da Rússia podem ter afetado a identidade russa de Tolstói, desse modo condicionando sua escolha de “identidades” para os personagens de alguns de seus romances (por exemplo, o de Pierre Bezukhov em Guerra e Paz).Fil: Adamovsky, Ezequiel Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto de Historia Argentina y Americana; Argentina; Universidad de Buenos Aires; Argentina