1,723,782 research outputs found
Feng shi Eluosi ri ji
No full text李仙根撰 ; 吳震方輯. 奉使俄羅斯日記 / 張鵬翮撰 ; 吳震方輯.Li Xiangen zhuan ; Wu Zhenfang ji. Feng shi Eluosi ri ji / Zhang Penghe zhuan ; Wu Zhenfang ji
Combining formal verification environments and model-driven engineering
No full textLes méthodes formelles (comme les prouveurs interactifs) sont de plus en plus utilisées dans la vérification de logiciels critiques. Elles peuvent compter sur leurs bases formelles solides ainsi que sur leurs sémantiques précises. Cependant, elles utilisent des notations complexes qui sont souvent difficiles à comprendre. D'un autre côté, l'Ingénierie Dirigée par les Modèles nous propose des langages de descriptions, comme les diagrammes de classes, utilisant des notations intuitives mais qui souffrent d'un manque de bases formelles. Dans cette thèse, nous proposons de faire interagir les deux domaines complémentaires que sont les méthodes formelles et l'ingénierie dirigée par les modèles. Nous proposons une approche permettant de transformer des types de données fonctionnels (utilisés dans les prouveurs interactifs) en diagrammes de classes et vice-versa. Afin d'atteindre ce but, nous utilisons une méthode de transformation dirigée par les modèles.Formal methods (such as interactive provers) are increasingly used in the verification of critical software. This is so because they rely on their strong formal basis and precise semantics. However, they use complex notations that are often difficult to understand. On the contrary, the tools and formalisms provided by Model Driven Engineering offer more attractive syntaxes and use intuitive notations. However, they suffer from a lack of formal foundations. In this thesis, we are interested in combining these two complementary domains that are formal methods and Model Driven Engineering. We propose an approach allowing to translate functional data types (used in interactive provers) into class diagrams and vice versa. To achieve this goal, we use a model-driven transformation method
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
T-COL: Generating Counterfactual Explanations for General User Preferences on Variable Machine Learning Systems
No full textTo address the interpretability challenge in machine learning (ML) systems, counterfactual explanations (CEs) have emerged as a promising solution. CEs are unique as they provide workable suggestions to users, instead of explaining why a certain outcome was predicted. The application of CEs encounters two main challenges: general user preferences and variable ML systems. On one hand, user preferences for specific values can vary depending on the task and scenario. On the other hand, the ML systems for verification may change while the CEs are performed. Thus, user preferences tend to be general rather than specific, and CEs need to be adaptable to variable ML models while maintaining robustness even as these models change. Facing these challenges, we propose general user preferences based on insights from psychology and behavioral science, and add the challenge of non-static ML systems as one preference. Moreover, we introduce a novel method, Tree-based Conditions Optional Links (T-COL) for generating CEs adaptable to general user preferences. Moreover, we employ T-COL to enhance the robustness of CEs with specific conditions, making CEs robust even when the ML models are replaced. To assess subjectivity preferences, we define LLM-based autonomous agents to simulate users and align them with real users. Experiments show that T-COL outperforms all baselines in adapting to general user preferences
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
VHF and UHF Electromagnetic Radiation Produced by Streamers in Lightning
Full text linkIn this letter, we report simulation results of streamer propagation and collision that produce electromagnetic radiation in the very high frequency (VHF) and ultra high frequency (UHF) bands. The streamers are initiated in overbreakdown field conditions, 1.5E(k)and2E(k), respectively, which may be found during the corona flash stage of negative leader stepping processes. We find that while streamer propagation produces stronger VHF radiation, the head-on collision of streamers dominates UHF, and even higher-frequency radiation. Analysis of the energy spectral densities obtained from different simulation cases shows that the total length and radii of colliding streamers, as well as the ambient field, are important parameters for the UHF radiation produced by streamer collisions. The larger those parameters are, the stronger UHF radiation produced. Finally, by comparing with the measured spectral magnitude of lightning field in the VHF range, it is found that there are probably 10(5)-10(7) streamers involved during the lightning corona flash stage. Plain Language Summary Despite being a familiar phenomenon, the physics of lightning initiation and propagation is not well understood. An effective approach to study lightning is to observe their radio frequency (RF) signals, which is especially critical for understanding the lightning activities inside thunderstorms, because clouds are opaque for other signals. The RF signals with frequencies above about 10MHz are commonly used to map/image lightning development. They are believed to be produced by the physical process electrically breaking down virgin air. Previous work has shown that electrical breakdown processes known as streamers, which are the precursors of lightning, can produce RF radiation below hundreds of megahertz. Our study investigates a physical process that enables lightning to produce RF radiation above hundreds of megahertz. We find that collisions between streamers can generate rapid increases of electrical current to produce RF emissions extending to tens of gigahertz. The results will be helpful for understanding and interpreting RF observations/measurements of lightning and will generate impact in the field of atmospheric and space electricity.PublishedYe
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