1,721,014 research outputs found
VIS-NIR reflectance analysis of (162173) Ryugu analogues mixtures and CC meteorites in the framework of Hayabusa2 mission
No full textQCM-based sensor for volatile organic compounds characterization
No full textThermogravimetry (TG) or Thermogravimetric Analysis (TGA) is a widely used technique to obtain information about thermal stability and composition and to monitor different thermal processes of materials. The TGA analysis is frequently used to monitor the deposition/sublimation and absorption/desorption processes of volatiles compounds in different environments: outgassing rates from degassing in space [1], dehydration and organics decomposition in minerals [2] and the fate of various materials in atmospheric environments [3]. In particular, it is possible to obtain a characterization of organic compounds by using Quartz Crystal Microbalance (QCM)-based sensors, equipped with an integrated heater in order to study the deposition and desorption processes. In this work, an organic compound (used as contaminant source) was characterized by using the breadboard of a QCM-based sensor, i.e. CAM (Contamination Assessment Microbalance), which shows several improvements compared to the previous Quartz Crystal Microbalance sensors used by European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) [1,4]. CAM instrument aims to monitor contaminants and outgassing materials which are released by spacecrafts during in-orbit space missions characterizing the contaminant source by means of Thermogravimetric technique. The organic compound desorption rates and the enthalpy of sublimation (ΔHsub) were retrieved by using the Langmuir relation while the sensor regeneration was obtained by means of thermal cycles by using the integrated heaters on crystal surface. The CAM breadboard validation, the experimental procedure and results are presented, and compared previous works
MOVIDA: an instrument for the characterization of lunar dust charging and levitation process and measurement of volatiles
No full textAssessment of TEC suitability for a low temperature QCM
No full textQuartz crystal microbalances have been used as measuring and monitoring devices for particle deposition on sensitive surfaces such as optical mirrors, thermal radiators, solar arrays, and other equipment used in space exploration. Moreover, microbalances have been applied in space to perform thermo-gravimetric analyses in order to infer about the type of volatile and condensable material. When the object of contamination monitoring is an intrinsically cold surface, e.g. a radiator, an effective cooling is required to achieve the same (or slightly lower) condensing temperature. The cooling problem of the microbalance sensing area has found promising solution from the use of thermoelectric coolers, the only compact and lightweight devices that can be housed in a typical microbalance envelope. Nevertheless, performance of the thermoelectric element at low temperature is a known issue so that restricts most applications above-40°C therefore there is a lack of data about performances below that temperature and characterization in expected environment is generally required. Thus, in this work cooling performance of commercial thermoelectric elements has been assessed at low temperature along with its survival to thermal cycling in off condition, in order to assess its applicability for the space borne microbalance under development
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Performance tests and qualification of VISTA, a microbalance for asteroids characterization for Hera mission
No full textTemperature sensitivity of a quartz crystal microbalance for TGA in Space
No full textThis research activity investigates the temperature-frequency relationship of quartz crystal microbalance for thermogravimetric analyses in space. The microbalance configuration is innovative because of built-in heater and temperature sensor made by metallic films deposited on the crystal. This configuration allows direct temperature measurement over the sensing area, an essential feature for a thermogravimetric sensor that must operate in a wide temperature range, in transient conditions and/or with unknown external heat flux. In fact, beside the deposited mass, the oscillating frequency of the crystal strongly depends on the temperature of the electrode area. In this work, the effect of the temperature on the microbalance frequency has been addressed for the case of uniform distribution, in the temperature range from -20°C to 100°C but the methodology hereafter presented, can be applied to vider temperature ranges where a specific microbilance might be required to operate
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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