1,721,136 research outputs found
Clustering geo-tagged tweets for advanced big data analytics
No full textIn this paper, we introduce an original approach thatexploits timestamped geo-tagged messages posted by Twitter usersthrough their smartphones when they travel to trace their trips.An original clustering technique is presented, that groups similartrips to define tours and analyze the popular tours in relationwith local geo-located territorial resources. This objective is veryrelevant for emerging big data analytics tools.Tools developed to reconstruct and mine the most populartours of tourists within a region are described which identify,track and group tourists' trips through a knowledge-based approachexploiting timestamped geo-tagged information associatedwith Twitter messages sent by tourists while traveling.The collected tracks are managed and shared on the Webin compliance with OGC standards so as to be able to analyzethe characteristic of localities visited by the tourists by spatialoverlaying with other open data, such as maps of Points Of Interest(POIs) of distinct type. The result is an novel Interoperableframework, based on web-service technology
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Improving usability and accessibility of cheminformatics tools for chemists through cyberinfrastructure and education
No full textSome of the latest trends in cheminformatics, computation, and the world wide web are reviewed with predictions of how these are likely to impact the field of cheminformatics in the next five years. The vision and some of the work of the Chemical Informatics and Cyberinfrastructure Collaboratory at Indiana University are described, which we base around the core concepts of e-Science and cyberinfrastructure that have proven successful in other fields. Our chemical informatics cyberinfrastructure is realized by building a flexible, generic infrastructure for cheminformatics tools and databases, exporting "best of breed" methods as easily-accessible web APIs for cheminformaticians, scientists, and researchers in other disciplines, and hosting a unique chemical informatics education program aimed at scientists and cheminformatics practitioners in academia and industry. © 2011/2012 - IOS Press and the authors. All rights reserved
Finite Element Solution of Thermal Convection On A Hypercube Concurrent Computer
No full textNumerical solutions to thermal convection flow problems
are vital to many scientific and engineering problems.
One fundamental geophysical problem is the thermal convection
responsible for continental drift and sea floor
spreading. The earth's interior undergoes slow creeping
flow (~cm/yr) in response to the buoyancy forces generated
by temperature variations caused by the decay of
radioactive elements and secular cooling. Convection in
the earth's mantle, the 3000 km thick solid layer between
the crust and core, is difficult to model for three reasons:
(1) Complex rheology -- the effective viscosity depends
exponentially on temperature, on pressure (or depth) and
on the deviatoric stress; (2) the buoyancy forces driving
the flow occur in boundary layers thin in comparison to the
total depth; and (3) spherical geometry -- the flow in the
interior is fully three dimensional. Because of these many
difficulties, accurate and realistic simulations of this process
easily overwhelm current computer speed and memory
(including the Cray XMP and Cray 2) and only simplified
problems have been attempted [e.g. Christensen and
Yuen, 1984; Gurnis, 1988; Jarvis and Peltier, 1982].
As a start in overcoming these difficulties, a number of
finite element formulations have been explored on hypercube
concurrent computers. Although two coupled equations
are required to solve this problem (the momentum
or Stokes equation and the energy or advection-diffusion
equation), we will concentrate our efforts on the solution
to the latter equation in this paper. Solution of the former
equation is discussed elsewhere [Lyzenga, et al, 1988].
We will demonstrate that linear speedups and efficiencies
of 99 percent are achieved for sufficiently large problems
Variations on the Author
Get PDF“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
A Robust Scheduler for Workflow Ensembles under Uncertainties of Available Bandwidth
No full textImprecise input data imposes special challenges to workflow scheduling. This paper introduces a robust scheduler based on particle swarm optimisation, called RobWE, which considers uncertainties of available bandwidth when producing schedules for workflow ensembles. The proposed scheduler is also a flexible scheduler since it allows the replacement of its objective function according to the user's needs. The effectiveness of the proposed RobWE scheduler is compared to a non-robust scheduler that does not consider the presence of such uncertainties. Results of simulations considering diverse scenarios, based on several degrees of uncertainty in available bandwidth estimates, characteristics of bandwidth estimations and workflow applications, demonstrate the advantages of the proposed RobWE scheduler.</p
Distributed Handler Architecture
Get PDFThesis (PhD) - Indiana University, Computer Sciences, 2007Over the last couple of decades, distributed systems have been demonstrated an architectural evolvement based on models including client/server, multi-tier, distributed objects, messaging and peer-to-peer. One recent evolutionary step is Service Oriented Architecture (SOA), whose goal is to achieve loose-coupling among the interacting software applications for scalability and interoperability. The SOA model is engendered in Web Services, which provide software platforms to build applications as services and to create seamless and loosely-coupled interactions. Web Services utilize supportive functionalities such as security, reliability, monitoring, logging and so forth. These functionalities are typically provisioned as handlers, which incrementally add new capabilities to the services by building an execution chain. Even though handlers are very important to the service, the way of utilization is very crucial to attain the potential benefits. Every attempt to support a service with an additive functionality increases the chance of having an overwhelmingly crowded chain: this makes Web Service fat. Moreover, a handler may become a bottleneck because of having a comparably higher processing time.
In this dissertation, we present Distributed Handler Architecture (DHArch) to provide an efficient, scalable and modular architecture to manage the execution of the handlers. The system distributes the handlers by utilizing a Message Oriented Middleware and orchestrates their execution in an efficient fashion. We also present an empirical evaluation of the system to demonstrate the suitability of this architecture to cope with the issues that exist in the conventional Web Service handler structures
Hypercube data analysis in astronomy: optical interferometry and millisecond pulsar searches
No full textAstronomical data sets are beginning to live up to their name, in both their sizes and the complexity of the analysis required. Here we discuss two astronomical data analysis problems which we have begun to implement on a hypercube concurrent processor environment: The intensive image processing required in an optical interferometry project, and the large scale power spectral analysis required by a search for millisecond-period radio pulsars. In both cases the analysis proceeds largely in the Fourier domain, and we find that the problems are readily adapted to a concurrent environment. In the following report, we outline briefly the astronomical background for each problem, then discuss the general computational requirements, and finally present possible hypercube algorithms and results achieved to date
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