1,720,975 research outputs found
The European ultrasonic planetary core drill: preliminary results from field trials at the Haughton Mars Project
No full textThis paper presents the findings of a recent field trip by the Ultrasonic Planetary Core Drill team to the Mars analog site at the Haughton Mars Project. Results of this trip are compared to results obtained drilling permafrost simulant in the lab
Ultrasonic planetary core drill: Overview and results from field trial
No full textIn the effort to explore the subsurface of terrestrial bodies, we seek to obtain better samples from ever greater depths. Many organisations are working towards technologies that can achieve this goal whilst ensuring compatibility with the likely requirements of planetary landers in terms of mass, power, and dimensions. The Ultrasonic Planetary Core Drill (UPCD) was an FP7 funded project which aimed to develop such a planetary sub-surface sample acquisition system, developing the required drill hardware and testing it in a Mars analogue environment in Antarctica. The objective was to reach 30cm and containerise the samples using the least possible power, while operating at low weight-on-bit. This has been broadly achieved within a conceptually-deployable package
UPCD: Field trial results and further work
No full textThe ultrasonic planetary core drill (UPCD) project sought to develop and conduct a field trial, in an analogous Martian environment, of a space-compatible regolith-sampling tool. The project implemented a number of key technologies to achieve this aim: a drilling control loop based on ultrasonic power feedback, a bayonet interface system to allow a drillstring to be built up in situ then disassembled after use, a coring design which captured the cores drilled out, and a mechanism for caching the core samples in sealable containers. The system was demonstrated in the laboratory with results indicating low power, low weight on bit, achievement of the targeted depth, and the retrieval of still-frozen core samples. The routines to allow the system to become fully autonomous were also demonstrated. The drill was deployed to Coal Nunatak on Alexander Island, Antarctica, for analogue trials. The drill was demonstrated to work, as was the caching and drill assembly/disassembly system, but the target depth was not achieved. A review of drill depth is provided along with a laboratory solution to the problems encountered in the field. Further work using the UPCD is also discussed
Development of a robust mating system for use in the autonomous assembly of planetary drill strings
Full text linkVolume-constrained robotic missions seeking to obtain samples from beneath a planetary subsurface may wish to use a rigid drill string consisting of multiple, individual drill bit sections connected together, as opposed to a single, lengthy drill bit. To ensure that drill strings can be assembled and disassembled reliably, it is essential that a robust connection system be used. The authors propose a geometry that seeks to address the requirements of such a mating interface. The proposed solution is based on the bayonet interface, using L- and T-shaped so-called female grooves and male studs connected and disconnected together through a series of clockwise and counterclockwise rotations and single-point clamping events. This routine allows the transfer of both percussion through the drill string and torque in both directions of rotation, while permitting the accurate disconnection of individual drills bits at the required location. Sustained laboratory and field drilling operations suggest that bayonet-style connections offer a reliable solution to the problem of autonomous assembly and disassembly of drill strings in a planetary exploration setting. This paper discusses the development of such a connection system, based on the bayonet connection, which has been implemented in the overall architecture of the Ultrasonic Planetary Core Drill (UPCD). The design trade-off study, which sought to evaluate the use of the bayonet system in comparison with the more conventional screw thread interface, will be discussed, alongside experimental results from percussion transmission testing and drill string assembly testing
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
European Ultrasonic Planetary Core Drill
No full textPaper presented at the 12th International Planetary Probe Workshop, Cologne, Germany, 15-19 June 201
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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