Modal characterization of the ASCIE segmented optics testbed: New algorithms and experimental results

New frequency response measurement procedures, on-line modal tuning techniques, and off-line modal identification algorithms are developed and applied to the modal identification of the Advanced Structures/Controls Integrated Experiment (ASCIE), a generic segmented optics telescope test-bed representative of future complex space structures. The frequency response measurement procedure uses all the actuators simultaneously to excite the structure and all the sensors to measure the structural response so that all the transfer functions are measured simultaneously. Structural responses to sinusoidal excitations are measured and analyzed to calculate spectral responses. The spectral responses in turn are analyzed as the spectral data become available and, which is new, the results are used to maintain high quality measurements. Data acquisition, processing, and checking procedures are fully automated. As the acquisition of the frequency response progresses, an on-line algorithm keeps track of the actuator force distribution that maximizes the structural response to automatically tune to a structural mode when approaching a resonant frequency. This tuning is insensitive to delays, ill-conditioning, and nonproportional damping. Experimental results show that is useful for modal surveys even in high modal density regions. For thorough modeling, a constructive procedure is proposed to identify the dynamics of a complex system from its frequency response with the minimization of a least-squares cost function as a desirable objective. This procedure relies on off-line modal separation algorithms to extract modal information and on least-squares parameter subset optimization to combine the modal results and globally fit the modal parameters to the measured data. The modal separation algorithms resolved modal density of 5 modes/Hz in the ASCIE experiment. They promise to be useful in many challenging applications

Apparatus for retaining and releasing a payload

An apparatus for latching an object, such as a payload for a space vehicle, includes an expandible latch which is shifted between a relaxed open condition and a flexed closed condition by actuation of a pair of temperature-responsive members, such as shaped memory alloy (SMA) coil springs. One of the two temperature-responsive members biases an actuator into a first position that allows the expandible latch to open. The other SMA member biases the actuator in the opposite position to close the expandible latch. Heating the appropriate SMA member causes the actuator to move from one position to the other position. In the preferred embodiment, no power is required to maintain the actuator in either position once the position has been established. For example, the actuator may have a rest position that allows the expandible latch to remain open when the two SMA members are cooled and allowed to reach an equilibrium condition with respect to applied force to the actuator. A detent-and-ball arrangement may be used to maintain the position of the actuator after the expandible latch has been closed

Estimation-based synthesis of H∞-optimal adaptive FIR filtersfor filtered-LMS problems

This paper presents a systematic synthesis procedure for H∞-optimal adaptive FIR filters in the context of an active noise cancellation (ANC) problem. An estimation interpretation of the adaptive control problem is introduced first. Based on this interpretation, an H∞ estimation problem is formulated, and its finite horizon prediction (filtering) solution is discussed. The solution minimizes the maximum energy gain from the disturbances to the predicted (filtered) estimation error and serves as the adaptation criterion for the weight vector in the adaptive FIR filter. We refer to this adaptation scheme as estimation-based adaptive filtering (EBAF). We show that the steady-state gain vector in the EBAF algorithm approaches that of the classical (normalized) filtered-X LMS algorithm. The error terms, however, are shown to be different. Thus, these classical algorithms can be considered to be approximations of our algorithm. We examine the performance of the proposed EBAF algorithm (both experimentally and in simulation) in an active noise cancellation problem of a one-dimensional (1-D) acoustic duct for both narrowband and broadband cases. Comparisons to the results from a conventional filtered-LMS (FxLMS) algorithm show faster convergence without compromising steady-state performance and/or robustness of the algorithm to feedback contamination of the reference signal

La notion d'anomie : généalogie d'un concept sociologique

Pour respecter une certaine manière de parler, qui n'est pas propre à notre discipline, nous avons évoqué dans le titre de notre mémoire "un" concept d'anomie, comme en physique par exemple on parle "du" concept de force. Toutefois, comme c'est le cas pour ce dernier concept, qui lui non plus ne renvoie pas directement à un observable, le concept d'anomie change de signification avec la théorie explicative dans laquelle il prend place et qui seule lui confère un sens précis, à tel point qu'il faudrait peut-être parler "des" concepts successifs d'anomie apparus en sociologie, plutôt que d' "un" concept et de son histoire. Dans ce mémoire nous procédons à une enquête épistémologique sur les divers concepts d'anomie construits par trois théoriciens à qui on doit associer l'usage du terme : Guyau, Durkheim, Merton

Globalization and political management: towards a reactive democracy

Nuestra sociedad se encuentra en un proceso de mutación. Cada día son más los índices que nos muestran que las estructuras políticas, económicas, y por lo tanto sociales y culturales se están modificando. Pero, ¿hacia dónde vamos? Analizando nuestras realidades a la luz de las reflexiones de varios autores, podemos empezar a vislumbrar las nuevas tendencias del próximo sistema político - económico post democracia.Our society is experiencing a mutation process. Everyday, more and more figures show us that political and economicalstructures change; therefore, social and cultural structures are alsobeing modified. But, where are we going? Analyzing our realities,according to some authors, we can start figuring out the new tendenciesfor the next political – economical post democracy system

EL TRATADO DE TAPIHUE ENTRE CIERTOS LINAJES MAPUCHES Y EL GOBIERNO DE CHILE (1825)

Indexación: Web of Science; ScieloThe document reproduced here is a photographic copy ofthe only printed version of the Tapihue Treaty, signed on January 7, 1825, by the patriot army colonel and commander in chiefofthe High Frontier, Pedro Barnechea, representing the Government ofChile and the principal chiefofthe alliance "llanista" Juan Mariluán,. It was the first ofseveral peace agreement sheld between the republic and the various lineages Mapuche groups after independence. While the content of the treaty has circulated before, a visual reproduction of the original form after being published by order ofCongress, in the workshops ofthe National Printing Office, Santiago de Chile, was not available. It is therefore a reliable picture of the "official" sponsored by the Chilean legislature. It is preceded by a presentation that explains the history surrounding its release, rediscovery and technical analysis. Likewise, this presentation provides comments relevant to the legal scope, anthropological and political content. It makes a special reflection on the political status acquired through the territory ofAraucania, one of the themes of this work, derivedfrom Fondecytproject on the development ofthe Mapuche society at the beginnings ofthe Chilean republic.Resumen: El documento reproducido es una copia fotográfica del único texto impreso del Tratado de Tapihue, suscrito el 7 de enero de 1825, por el coronel del ejército patriota y comandante en jefe de la Alta Frontera, Pedro Barnechea, en representación del gobierno de Chile, y el cacique principal de la alianza "llanista", Juan Mariluán; el primero de varios acuerdos de paz llevados a cabo entre la república y las diversas parcialidades mapuches, tras la Independencia. Si bien el contenido del tratado ha sido muy difundido últimamente, nunca se había efectuado una reprografía visual del impreso original, tras su publicación, por orden del Congreso Nacional, en los talleres de la Imprenta Nacional, de Santiago de Chile. Se trata, por consiguiente, de una imagen fidedigna de la versión "oficial" patrocinada por el poder legislativo chileno. Va precedido de una presentación que ilustra al lector sobre los antecedentes que rodearon su edición, redescubrimiento y análisis técnico. Asimismo, se brindan comentarios pertinentes a los alcances jurídicos, antropológicos y políticos de su contenido. Se formula una especial reflexión en torno al estatus político adquirido por el territorio de la Araucanía, uno de los ejes temáticos de este trabajo, derivado de un proyecto Fondecyt relativo al devenir de la sociedad en los orígenes de la república.http://ref.scielo.org/v4fcq

Estimation-based multi-channel adaptive algorithm for filtered-LMS problems

This paper presents an estimation-based adaptive filtering algorithm for the multi-channel Filtered-LMS problems where a number of adaptively controlled secondary sources use multiple reference signals to cancel the effect of a number of primary sources (i.e. disturbance sources) as seen by a number of error sensors. We show that our estimation based approach easily extends to the multi-channel case, and that it maintains all of the stability and performance features of the single-channel solution. The problem of noise cancellation in a one dimensional acoustic duct, and a structural vibration control problem are chosen to examine the main characteristics of the proposed multi-channel adaptive algorithm. The performance of the new multi-channel adaptive algorithm is compared to the performance of a multi-channel implementation of the FAMS algorithm in these cases, and it is shown that the new algorithm provides a faster response, with improved transient behavior and steady-state performance

Solução para a mediterraneidade da Bolivia: uma proposta desde o Chile

After the signing of the 1904 Treaty between Chile and Bolivia, the former was left without a sovereign outlet to the Pacific Ocean. This article gives an account of how Chile throughout the twentieth century has had as a State policy, finding a formula to give Bolivia access to the sea. In addition, this paper presents a proposal to solve Bolivia's landlocking, based on the experience of the Antarctic Treaty of 1959 and finally, analyzes the power relations involved that facilitate or impede a solution.Tras la firma del Tratado de 1904 suscrito entre Chile y Bolivia, este último Estado se quedó sin una salida soberana al océano pacífico. El presente artículo da cuenta de cómo Chile a lo largo del siglo XX ha tenido como política de Estado buscar alguna fórmula para brindarle acceso al mar a Bolivia. Además, este artículo presenta una propuesta para solucionar la mediterraneidad de Bolivia, basada en la experiencia del Tratado Antártico de 1959, y finalmente analiza las relaciones de poder involucradas que facilitarían o impedirían una solución.Após a assinatura do Tratado de 1904 entre o Chile e a Bolívia, este último Estado foi deixado sem uma saída soberana para o Oceano Pacífico. Este artigo descreve como o Chile no decorrer do século XX manteve uma política de Estado a fim de encontrar uma fórmula para dar à Bolívia um acesso ao mar. Além disso, este trabalho apresenta uma proposta para resolver a mediterraneidade da Bolívia, com base na experiência do Tratado Antártico de 1959 e, finalmente, analisa as relações de poder envolvidas que facilitaria ou impediria uma solução

Desenvolvimento nuclear: outono ou primavera para a proliferação em atores estatais?

This paper presents the status of nuclear proliferation from the point of view of States. Using the international nuclear regime, an analysis is made of the performance of the nuclear States, the situation of intermediate powers and who constitutes a threat to the international system. The main hubs where the discussion deepens are: the growing group of nuclear States, the continual increase of nuclear reactors in the world in order to meet the high global demand for electricity, and the erosion in the specifics of the nuclear nonproliferation regime. Among the key conclusions, a case is mentioned of the direct relationship between the International Security Agenda and the development of nuclear weapons in order to balance the State relations under different regional dynamics, where States allocate resources for research and military spending in order to achieve technological advances, which become the basis to support their options, interests and ambitions in the international system.El presente artículo tiene como objetivo exponer la situación de la proliferación nuclear desde los actores estatales. Por medio del régimen nuclear internacional se analiza el desempeño de los Estados nucleares, la situación de las potencias intermedias y quienes constituyen una amenaza para el sistema internacional. Los ejes destacados en que se profundiza la discusión, son la ampliación del grupo de Estados nucleares, el aumento sostenido de los reactores nucleares en el mundo con el propósito de suplir la alta demanda de energía eléctrica mundial, y la erosión en los hechos del régimen de no proliferación nuclear. Entre las principales conclusiones se argumenta la relación directa entre la Agenda de Seguridad Internacional y el desarrollo de armas nucleares con el objetivo de balancear las relaciones interestatales según las diferentes dinámicas regionales, donde los Estados destinan recursos a investigación y gasto militar con el objetivo de lograr avances tecnológicos, los cuales se constituyen en la base para sustentar sus opciones, intereses y pretensiones en relación al sistema internacional.Este artigo tem como objetivo explicar a situação da proliferação nuclear desde a perspectiva dos atores estatais. Por meio do regime nuclear internacional analisa-se o desempenho dos Estados nucleares, a situação das potências medianas e aqueles que representam uma ameaça para o sistema internacional. Os principais eixos em que a discussão se aprofunda são a ampliação do grupo de Estados nucleares, o aumento contínuo dos reatores nucleares em todo o mundo com o propósito de atender a alta demanda de energia elétrica global e um desgaste nas práticas do regime de não proliferação nuclear. Entre as principais conclusões, argumenta-se sobre a relação direta entre a Agenda de Segurança Internacional e o desenvolvimento de armas nucleares com o objetivo de equilibrar as relações interestatais conforme as diferentes dinâmicas regionais, nas quais os Estados injetam recursos para pesquisa e gasto militar a fim de alcançar avanços tecnológicos, que constituem a base para sustentar as suas escolhas, interesses e pretensões no que diz respeito ao sistema internacional