1,720,954 research outputs found
Asynchronous data transfers on large scale HPC systems with experiments on the CRAY XT3/XT4
No full textA key challenge faced by the emerging large scale scientific and engineering simulations is effectively and efficiently managing the large volumes of heterogeneous data generated. This includes offloading this data from the compute nodes at runtime, and transferring it over to service nodes or remote clusters for online
monitoring, analysis, or archiving. To be effective, these I/O operations should not impose additional synchronization penalties on
the simulation, should have minimal impact on the computational performance, maintain overall Quality of Service, and ensure that no data is lost.
This thesis describes the design, implementation, and operation of DART (Decoupled Asynchronous Remote Transfers). DART is a thin software layer built on RDMA (Remote Direct Memory Access) communication technology, and specifically the Portals RDMA library to allow fast, low-overhead access to data from simulations running on compute elements, and to support high-throughput low latency
asynchronous I/O transfer of this data.
DART is part of the infrastructure for an integrated simulation of fusion plasma in a Tokamak being developed at the Center for Plasma Edge Simulation (CPES), a DoE Office of Fusion Energy Science (OFES) Fusion Simulation Projects (FSP). A performance evaluation on the Cray XT3/XT4 system at Oak Ridge National Laboratory demonstrates that DART can be used to offload expensive I/O operations to dedicated service nodes allowing more efficient utilization of the compute elements.M.S.Includes bibliographical references (p. 41-42)
Enabling dynamic interactions in large scale applications and scientific workflows using semantically specialized shared DataSpaces
No full textEmerging scientific and engineering applications use large-scale parallel machines to simulate, with higher accuracy, complex physical phenomena consisting of dynamically interacting processes. The workflows associated with these applications consist of parallel application codes that need to co- ordinate and interact at runtime. The interactions typically involve large volumes of data that must be exchanged and processed by the codes. The heterogeneous nature of the coupled codes, their numerical formulations, and their data decompositions lead to complex and dynamic interaction and data exchange patterns that are only defined at runtime. Moreover, these simulations often run on separate resources and progress at different rates, which adds to their complexity. Efficient and scalable implementation of these coupled application workflows present several challenging programming, orchestration, coordination, and data exchange requirements. Existing programming frameworks, however, are rigid and provide limited support for the dynamic inter- actions manifested by these applications. For example, existing frameworks need to gather global application knowledge, impose tight synchronization between applications, or demand pre-defined and static interaction patterns that must be known prior to execution. These constraints can introduce significant performance penalties and can limit application interaction programming expressiveness. This thesis explores a new communication and coordination model to enable flexible and asynchronous application coupling for coupled applications workflows. It derives from the tuple-space model and provides the abstraction of a virtual distributed shared-space, which is customized for the application data domain. It enables applications to coordinate and exchange data by inserting and retrieving data objects. This model does not impose any synchronization requirements between independent applications. Data stored on the space can be accessed by multiple applications, which can associatively query the space and retrieve data objects. Furthermore, it enables decoupled and dynamic interactions driven by application computations. This thesis presents DataSpaces, a prototype implementation of the distributed shared-space model. DataSpaces enables memory-to-memory application coupling and transparent data redistribution. It can complement existing workflow engines to enable in-memory data transports between distributed applications that run on separate resources as part of end-to-end scientific workflows. The thesis also presents ActiveSpaces, which extends DataSpaces and the shared-space model to enable in-transit data processing. It proposes and demonstrates a shift in the data processing paradigm by moving processing code closer to the data. ActiveSpaces provides programming support for defining data processing routines, and a runtime execution system to deploy and remotely execute these routine on the space. The research concepts and software frameworks have been deployed and evaluated using real application workflows in production runs on high-end computing systems.Ph. D.Includes bibliographical referencesIncludes vitaby Ciprian Doca
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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