Construction and performance of an inverted pendulum thrust balance

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 133-134).The objective of the work in this thesis was to devise a means of profiling the thrust of the MIT Space Propulsion Lab's (SPL) Diverging Cusped Field (DCF) thruster and, more generally, other thrusters of similar size and thrust levels. The former SPL thrust stand, which had been used to characterize the BHT-200 engine, was not suitable for the DCF because of its torsional style design. An entirely new, inverted pendulum-type balance needed to be built. The new design employs a vertical arm with the DCF situated at the top and a counterweight placed at the bottom. The vertical arm rotates at the fulcrum through a flexible pivot attached to a base. A horizontal thrust force from the DCF causes the balance to rotate. This motion is sensed by a linear variable differential transformer (LVDT) and counteracted by a force from a voice coil. The voice coil's neutralizing force nulls the balance back to an equilibrium position and supplies the thrust value produced by the DCF. The inverted pendulum thrust balance was built from an initial design proposed by Professor Manuel Martinez-Sanchez. Many of the electrical components found on the old thrust stand, like the LVDT and the voice coil, were incorporated into the new one. Additionally, the control software and hardware from the old stand required several changes and updates to be compatible with the new design. After the assembly of the new thrust balance, the issues of calibration and thermal drift during use were also addressed. Once a means of correcting the undesired operational forces and thermal effects had been established, the balance displayed thrust measurement within a range of 0mN to 23mN with an uncertainties as low as ±0.5mN.by Brett R. Tartler.S.M

A Conservação Preventiva como Mecanismo de Efetivação da Trilogia Museológica: Musealização, Pesquisa e Gestão

This article aims to alert to need for museums to develop a model of museological management based on the fieldof Preventive Conservation as a heritage protection policy. The result of a Master's thesisof one of the authors, it proposes to consider the Museological Trilogy, here understood in the context of musealization processes, museological research and collection management, with the main interface between these axes being Conservation, as a preservation strategy. Pervades somecharacteristics of Preventive Conservation in collections with plastic material, in order to rethink the scope of Preventive Conservation in Museums. Diffusion and access to heritage, asset management policy ensuring preservation. As a theoretical framework, it works with the Getty (GCI) and Canadian (CCI) conservation institutes, as well as research references on conservation in museum plastic objects. Preventive Conservation of museum properties implies the application of actionson the surroundings of materiality, aiming to ensure their original characteristics and, thus, the possibilities of research and reflection on identity.Este artigo tem como propósito alertar para a necessidade de os museus desenvolverem um modelo de gestão museológica fundamentada no campo da Conservação Preventiva como uma política de proteção patrimonial. Resultado da dissertação de Mestrado de uma das autoras, propõe considerar a Trilogia Museológica, aqui entendida no âmbito dos processos de musealização, a pesquisa museológica e a gestão de acervos, tendo como principal interface entre esses eixos a Conservação, como estratégia de preservação. Perpassa algumas características da Conservação Preventiva em acervos com materialidade plástica, a fim de repensar o âmbito da Conservação Preventiva em Museus. Como referencial teórico, trabalha com os institutos de conservação Getty (GCI) e Canadian (CCI), bem como com referências de pesquisas sobre conservação em objetos plásticos musealizados. A Conservação Preventiva dos bens musealizados implica na aplicação de ações sobre o entorno da materialidade,visando assegurar suas características originais e assim, as possibilidades de pesquisa ede reflexão sobre identidad

A Formação na Maturidade como Apropriação da Própria História de Vida

No presente artigo, a disposição e a competência para a apropriação da própria história de vida são consideradas como modos de formação1 na maturidade. Estas se relacionam com fatores históricos e sócio-políticos e estão inscritas em contextos multigeracionais de formação e processos de desenvolvimento ao longo da vida. Nesta perspectiva, conceitos como geração, geracionalidade, geratividade e transmissão transgeracional ganham destaque e serão aprofundados no texto. A linha argumentativa que sustenta este ponto de vista baseia-se em estudos de países de língua alemã sobre crianças da Segunda Guerra Mundial que envelheceram. Apesar de se tratar de uma situação específica, nos parece possível a extensão das reflexões também para o contexto brasileiro

Beherrschung von Variabilitätsproblemen in Linux und verwandter hoch-konfigurierbarer Systemsoftware

The compile-time configuration mechanisms of modern system software allow the adaptation to a broad range of supported hardware architectures and application domains. Linux is hereby a both prominent and good example: In version 3.2, Linux provides more than 12.000 user-configurable configuration options, growing rapidly. This high amount of configurability imposes big challenges for developers. First, the declared variability in the configuration tooling, and what is actually implemented in the code, have to be kept in sync. If performed manually, this is a tedious and error-prone task. Second, alternatives implemented in the code make the use of tools for static analysis challenging. Finally, the overwhelming amount of configuration options make finding the best configuration for a given use-case hard for system integrators and developers. In this thesis, I analyze the variability mechanisms in Linux and related system software, in which I reveal many inconsistencies between the variability declaration and implementation. Many of these inconsistencies are hereby provably actual programming errors. It turns out that the extracted variability model is useful for additional applications. The formalized model helps developers with employing existing tools for static analysis more effectively. This allows the systematic revelation of bugs that are hidden under seldom tested configurations. Moreover, my approach enables the construction of a minimal Linux configuration with the extracted variability model and a run-time analysis of the system. This enables system administrators to compile and operate a Linux kernel with significantly reduced attack-surface, which makes the system more secure. In the end, my approach allows the holistic mastering of compile-time variability across the language barriers of the employed tools Kconfig, make and CPP.Die von moderner Systemsoftware angebotenen Konfigurationsmechanismen erlauben die Anpassung an eine breite Auswahl von unterstützten Hardwarearchitekturen und Anwendungsdomänen. Linux ist hierbei ein sowohl prominentes als auch gutes Beispiel: In Version 3.2 bietet Linux mehr als 12.000 vom Benutzer steuerbare Konfigurationsschalter, mit stark steigender Tendenz. Dieses hohe Maß an Konfigurierbarkeit stellt Entwickler vor große Herausforderungen. Zum einen muss die in den Konfigurationswerkzeugen deklarierte, mit der im Programmtext umgesetzten Variabilität in Einklang gehalten werden. Bei händischer Durchführung stellt dies einen mühsamen und fehleranfälligen Arbeitsschritt dar. Zum anderen erschweren die im Programmtext programmierten Alternativen den Einsatz von statischen Analysewerkzeugen. Schließlich macht die überwältigende Anzahl an Konfigurationsoptionen es Systemintegratoren und Entwicklern schwer, die für einen gegebenen Anwendungsfall beste Belegung der Konfigurationsschalter zu finden. In dieser Arbeit analysiere ich die Variabilitätsmechanismen in Linux und verwandter Systemsoftware, bei der ich im ersten Schritt viele Inkonsistenzen zwischen der Deklaration und Umsetzung von Variabilität aufdecke. Viele dieser Inkonsistenzen sind dabei nachweislich tatsächliche Programmierfehler. Es stellt sich dabei heraus, dass das extrahierte Variabilitätsmodell auch für weitere Anwendungen nützlich ist. So hilft das formalisierte Modell Entwicklern bestehende statische Analysewerkzeuge effektiver einsetzen zu können. Dies erlaubt die systematische Aufdeckung von Programmfehlern, die in selten gewählten Konfigurationen verborgen sind. Darüber hinaus ermöglicht mein Ansatz die Konstruktion einer minimalen Konfiguration mit dem extrahierten Variabilitätsmodell und einer Laufzeitanalyse des Systems. Dies ermöglicht es Systemadministratoren einen Linux-Kern mit einer deutlich verkleinerten Angriffsfläche zu übersetzen und zu betreiben, was die Sicherheit des Gesamtsystems deutlich erhöht. Letztendlich erlaubt mein Ansatz die ganzheitliche Beherrschung der Variabilität in Linux zur Übersetzungszeit über die Sprachgrenzen der eingesetzten Werkzeuge Kconfig, make und CPP, hinweg

O percurso do objeto pela trilogia museológica como estratégia de conservação preventiva : musealização, pesquisa e gestão em acervos com objetos de plástico em museus públicos no Rio Grande do Sul, Brasil

Aborda o percurso de objetos plásticos em museus públicos do Rio Grande do Sul, Brasil, sob a perspectiva da Musealização, da Pesquisa Museológica e da Gestão de Museus e de Acervos. Propõe considerar a Trilogia Museológica como estratégia de preservação. Enfatiza as características da Conservação Preventiva em acervos com materialidade plástica, a fim de repensar o âmbito da Conservação Preventiva em Museus e ao Patrimônio. Como referencial teórico, trabalha com os institutos de conservação Getty (GCI) e Canadian (CCI), bem como com referências de pesquisas sobre conservação em objetos plásticos musealizados. A metodologia é qualitativa, a qual se concentra em pesquisa documental, observação direta nos museus pesquisados e quadro metodológico e conceitual. Apresenta proposta metodológica para reflexão sobre os acervos em materialidade plásticas observados nas instituições Museu Julio de Castilhos e Museu de Arte Contemporânea do Rio Grande do Sul. Diante da quase inexistência de bibliografia que trate especificamente da conservação preventiva de objetos de materialidade plástica, espera-se contribuir para pesquisas futurasIt approaches the path of plastic objects in public museums of Rio Grande do Sul, Brazil, from the perspective of Musealization, Museological Research and Museum and Collection Management. It proposes to consider the Museological Trilogy as a preservation strategy. Emphasizes the characteristics of Preventive Conservation in collections with plastic material, in order to rethink the scope of Preventive Conservation in Museums and Heritage. As a theoretical framework, he works with the Conservation Institutes Getty (GCI) and Canadian (CCI), as well as research references on conservation in musealised plastic objects. The methodology is qualitative, which focuses on documentary research, direct observation in the researched museums and methodological and conceptual framework. It presents a methodological proposal for reflection on the collections in plastic materiality observed in the institutions Julio de Castilhos Museum and Museum of Contemporary Art of Rio Grande do Sul. Given the almost inexistence of bibliography that specifically deals with the preventive conservation of plastic material objects, it is expected contribute to future research