123 research outputs found

    Rapid Diagnostics of Onboard Sequences

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    Keeping track of sequences onboard a spacecraft is challenging. When reviewing Event Verification Records (EVRs) of sequence executions on the Mars Exploration Rover (MER), operators often found themselves wondering which version of a named sequence the EVR corresponded to. The lack of this information drastically impacts the operators diagnostic capabilities as well as their situational awareness with respect to the commands the spacecraft has executed, since the EVRs do not provide argument values or explanatory comments. Having this information immediately available can be instrumental in diagnosing critical events and can significantly enhance the overall safety of the spacecraft. This software provides auditing capability that can eliminate that uncertainty while diagnosing critical conditions. Furthermore, the Restful interface provides a simple way for sequencing tools to automatically retrieve binary compiled sequence SCMFs (Space Command Message Files) on demand. It also enables developers to change the underlying database, while maintaining the same interface to the existing applications. The logging capabilities are also beneficial to operators when they are trying to recall how they solved a similar problem many days ago: this software enables automatic recovery of SCMF and RML (Robot Markup Language) sequence files directly from the command EVRs, eliminating the need for people to find and validate the corresponding sequences. To address the lack of auditing capability for sequences onboard a spacecraft during earlier missions, extensive logging support was added on the Mars Science Laboratory (MSL) sequencing server. This server is responsible for generating all MSL binary SCMFs from RML input sequences. The sequencing server logs every SCMF it generates into a MySQL database, as well as the high-level RML file and dictionary name inputs used to create the SCMF. The SCMF is then indexed by a hash value that is automatically included in all command EVRs by the onboard flight software. Second, both the binary SCMF result and the RML input file can be retrieved simply by specifying the hash to a Restful web interface. This interface enables command line tools as well as large sophisticated programs to download the SCMF and RMLs on-demand from the database, enabling a vast array of tools to be built on top of it. One such command line tool can retrieve and display RML files, or annotate a list of EVRs by interleaving them with the original sequence commands. This software has been integrated with the MSL sequencing pipeline where it will serve sequences useful in diagnostics, debugging, and situational awareness throughout the mission

    The Brexit Botnet and User-Generated Hyperpartisan News

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    In this paper we uncover a network of Twitterbots comprising 13,493 accounts that tweeted the U.K. E.U. membership referendum, only to disappear from Twitter shortly after the ballot. We compare active users to this set of political bots with respect to temporal tweeting behavior, the size and speed of retweet cascades, and the composition of their retweet cascades (user-to-bot vs. bot-to-bot) to evidence strategies for bot deployment. Our results move forward the analysis of political bots by showing that Twitterbots can be effective at rapidly generating small to medium-sized cascades; that the retweeted content comprises user-generated hyperpartisan news, which is not strictly fake news, but whose shelf life is remarkably short; and, finally, that a botnet may be organized in specialized tiers or clusters dedicated to replicating either active users or content generated by other bots

    Surface chemical and color characterization of juvenile tectona grandis wood subjected to steam-drying treatments

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    ArtículoThe color of Tectona grandis wood is an attribute that favors its commercialization, however, wood color from fast-growth plantation trees is clear and lacks uniformity. The aim of this work is to characterize steamed teak wood by means of the Fourier transform infrared spectroscopy (FTIR) and L a b color systems. Two moisture conditions (green and 50%) and two grain patterns (°at and quarter) of boards were analyzed through the application of di®erent steaming times (0, 3, 6, 9, 12, 15 and 18 h). The FTIR results showed that the bands at 1158, 1231, 1373 and 1419 cm 1 did not show any change with steaming, whereas the bands at 1053, 1108, 1453, 1506, 1536, 1558, 1595, 1652, 1683, 1700 and 1733 cm 1 presented a decrease in the intensity with the steaming time. The band at 1318 cm 1 was the only one that increased. Lightness (L ) was the most a®ected parameter, followed by yellowness (b ), while redness (a ) showed the smallest change. Surface color change ( E ) presented the lowest value between 3 h and 6 h of steam-drying in the boards with °at grain, whereas for boards with quarter grain, the smallest E value was obtained after 18 h of steaming

    New technologies and firm organization : the case of electronic traceability systems in French agribusiness

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    This paper considers the relationship between the adoption of electronic traceability systems (ETSs) and the organization of firms. More precisely, it analyzes the respective roles of a firm's organizational structure, and organizational changes, in the process of ETS adoption in agribusiness. We use data from the French "Organizational Changes and Computerization" survey from 2006. We test a probit model to demonstrate the organizational structure and organizational changes underlying the firm's ETS adoption choice. Results show that ETS adoption is strongly favored by organizations with heavy hierarchical structures, standardized managerial practices and contractual mechanisms with external partners. This adoption process seems to coevolve with the organization: firms that implemented an ETS during the observed period (2003-2006) have experienced the most important organizational changes in terms of managerial practices, information systems and contractual relations, as well as the strengthening of the intermediate levels in the hierarchy

    Participant Perceptions of Twitter Research Ethics

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    Social computing systems such as Twitter present new research sites that have provided billions of data points to researchers. However, the availability of public social media data has also presented ethical challenges. As the research community works to create ethical norms, we should be considering users’ concerns as well. With this in mind, we report on an exploratory survey of Twitter users’ perceptions of the use of tweets in research. Within our survey sample, few users were previously aware that their public tweets could be used by researchers, and the majority felt that researchers should not be able to use tweets without consent. However, we find that these attitudes are highly contextual, depending on factors such as how the research is conducted or disseminated, who is conducting it, and what the study is about. The findings of this study point to potential best practices for researchers conducting observation and analysis of public data
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