158 research outputs found
Leveraging Semantic Web Technologies for Managing Resources in a Multi-Domain Infrastructure-as-a-Service Environment
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
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
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
km/s and the dispersion of the kick distribution to
km/s at 90 % confidence. We find that a Blaauw kick cannot be ruled out and
}that at least about was lost during the supernova with 90 %
confidence. The pre-SN orbital separation is found to be robustly constrained
to be around AU.Comment: 13 pages, 5 figure
Metropolitan Wi-Fi Research Network at the Los Angeles State Historic Park
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. 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. 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
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
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
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
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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