158 research outputs found

    Leveraging Semantic Web Technologies for Managing Resources in a Multi-Domain Infrastructure-as-a-Service Environment

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    This paper reports on experience with using semantically-enabled network resource models to construct an operational multi-domain networked infrastructure-as-a-service (NIaaS) testbed called ExoGENI, recently funded through NSF's GENI project. A defining property of NIaaS is the deep integration of network provisioning functions alongside the more common storage and computation provisioning functions. Resource provider topologies and user requests can be described using network resource models with common base classes for fundamental cyber-resources (links, nodes, interfaces) specialized via virtualization and adaptations between networking layers to specific technologies. This problem space gives rise to a number of application areas where semantic web technologies become highly useful - common information models and resource class hierarchies simplify resource descriptions from multiple providers, pathfinding and topology embedding algorithms rely on query abstractions as building blocks. The paper describes how the semantic resource description models enable ExoGENI to autonomously instantiate on-demand virtual topologies of virtual machines provisioned from cloud providers and are linked by on-demand virtual connections acquired from multiple autonomous network providers to serve a variety of applications ranging from distributed system experiments to high-performance computing

    Why the economy still plays a major role in shaping support for European integration

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    The success of Eurosceptic parties is often attributed to cultural factors such as the strength of citizens’ national identities. Chase Foster and Jeff Frieden write that while these cultural considerations can help predict support for European integration, the importance of economic factors should not be overlooked. Drawing on a new study, they illustrate that every percentage-point increase in average unemployment in the EU is associated with a two percentage-point decline in favourable views toward EU membership

    Direct Statistical Constraints on the Natal Kick velocity of a Black Hole in an X-ray Quiet Binary

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    In recent years, a handful of ``dark" binaries have been discovered with a non-luminous compact object. Astrometry and radial velocity measurements of the bright companion allow us to measure the post-supernova orbital elements of such a binary. In this paper, we develop a statistical formalism to use such measurements to infer the pre-supernova orbital elements, and the natal kick imparted by the supernova (SN). We apply this formalism to the recent discovery of an X-ray quiet binary with a black hole, VFTS 243, in the Large Magellanic Cloud. Assuming an isotropic, Maxwellian distribution on natal kicks and using broad agnostic mass priors, we find that kick velocity can be constrained to Vk<72V_k < 72 km/s and the dispersion of the kick distribution to σk<68\sigma_k < 68 km/s at 90 % confidence. We find that a Blaauw kick cannot be ruled out and }that at least about 0.6M0.6 M_{\odot} was lost during the supernova with 90 % confidence. The pre-SN orbital separation is found to be robustly constrained to be around 0.30.3 AU.Comment: 13 pages, 5 figure

    Metropolitan Wi-Fi Research Network at the Los Angeles State Historic Park

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    UCLA is deploying a metropolitan-scale Wi-Fi mesh network near Downtown Los Angeles. It supports research in community-based urban participatory sensing, which focuses on how people can use their everyday mobile phones as sensors for data gathering on personal, community, and urban scales.&nbsp; Moreover, we will use it to explore Cultural Civic Computing, a service-oriented urban computing model in which neighborhoods power the processes of imagining, specifying, and designing technology infrastructure for public places. This work provides infrastructure with which to explore the potential that a large scale Wi-Fi deployment offers multicultural communities in investigating and reclaiming their own environments, and creating healthy and livable cities.&nbsp; It also enables public exploration of creativity and cultural identity, as well as the diverse histories of our cities and neighborhoods

    Video capture and post-processing technique for approximating 3D projectile trajectory

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    In this paper we introduce a low-cost procedure and methodology for markerless projectile tracking in three-dimensional (3D) space. Understanding the 3D trajectory of an object in flight can often be essential in examining variables relating to launch and landing conditions. Many systems exist to track the 3D motion of projectiles but are often constrained by space or the type of object the system can recognize (Qualisys, Göteborg, Sweden; Vicon, Oxford, United Kingdom; Opti-Track, Corvallis, Oregon USA; Motion Analysis, Santa Rosa, California USA; Flight Scope, Orlando, Florida USA). These technologies can also be quite expensive, often costing hundreds of thousand dollars. The system presented in this paper utilizes two high-definition video cameras oriented perpendicular to each other to record the flight of an object. A postprocessing technique and subsequent geometrically based algorithm was created to determine 3D position of the object using the two videos. This procedure and methodology was validated using a gold standard motion tracking system resulting in a 4.5 ± 1.8% deviation from the gold standard

    Video capture and post-processing technique for approximating 3D projectile trajectory

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    In this paper we introduce a low-cost procedure and methodology for markerless projectile tracking in three-dimensional (3D) space. Understanding the 3D trajectory of an object in flight can often be essential in examining variables relating to launch and landing conditions. Many systems exist to track the 3D motion of projectiles but are often constrained by space or the type of object the system can recognize (Qualisys, Göteborg, Sweden; Vicon, Oxford, United Kingdom; Opti-Track, Corvallis, Oregon USA; Motion Analysis, Santa Rosa, California USA; Flight Scope, Orlando, Florida USA). These technologies can also be quite expensive, often costing hundreds of thousand dollars. The system presented in this paper utilizes two high-definition video cameras oriented perpendicular to each other to record the flight of an object. A postprocessing technique and subsequent geometrically based algorithm was created to determine 3D position of the object using the two videos. This procedure and methodology was validated using a gold standard motion tracking system resulting in a 4.5 ± 1.8% deviation from the gold standard

    A Black Hole Kicked At Birth: MAXI J1305-704

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    When a compact object is formed in a binary, any mass lost during core collapse will impart a kick on the binary's center of mass. Asymmetries in this mass loss would impart an additional natal kick on the remnant black hole or neutron star, whether it was formed in a binary or in isolation. While it is well established that neutron stars receive natal kicks upon formation, it is unclear whether black holes do as well. Here, we consider the low-mass X-ray binary MAXI J1305-704, which has been reported to have a space velocity \gtrsim 200 km/s. In addition to integrating its trajectory to infer its velocity upon formation of its black hole, we reconstruct its evolutionary history, accounting for recent estimates of its period, black hole mass, mass ratio, and donor effective temperature from photometric and spectroscopic observations. We find that if MAXI J1305-704 formed via isolated binary evolution in the thick Galactic disk, then its black hole received a natal kick of at least 70 km/s with 95\% confidence.Comment: To be submitted; 9 pages, 5 figure
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