4,891 research outputs found
An approach to rollback recovery of collaborating mobile agents
Fault-tolerance is one of the main problems that must be resolved to improve the adoption of the agents' computing paradigm. In this paper, we analyse the execution model of agent platforms and the significance of the faults affecting their constituent components on the reliable execution of agent-based applications, in order to develop a pragmatic framework for agent systems fault-tolerance. The developed framework deploys a communication-pairs independent check pointing strategy to offer a low-cost, application-transparent model for reliable agent- based computing that covers all possible faults that might invalidate reliable agent execution, migration and communication and maintains the exactly-one execution property
Passive wireless tags for tongue controlled assistive technology interfaces
Tongue control with low profile, passive mouth tags is demonstrated as a humanâdevice interface by communicating values of tongue-tag
separation over a wireless link. Confusion matrices are provided to demonstrate user accuracy in targeting by tongue position. Accuracy is
found to increase dramatically after short training sequences with errors falling close to 1% in magnitude with zero missed targets. The
rate at which users are able to learn accurate targeting with high accuracy indicates that this is an intuitive device to operate. The
significance of the work is that innovative very unobtrusive, wireless tags can be used to provide intuitive humanâcomputer interfaces
based on low cost and disposable mouth mounted technology. With the development of an appropriate reading system, control of assistive
devices such as computer mice or wheelchairs could be possible for tetraplegics and others who retain fine motor control capability of
their tongues. The tags contain no battery and are intended to fit directly on the hard palate, detecting tongue position in the mouth with
no need for tongue piercings
The fission yeast FANCM ortholog directs non-crossover recombination during meiosis
Peer reviewedPostprin
CloudScope: diagnosing and managing performance interference in multi-tenant clouds
© 2015 IEEE.Virtual machine consolidation is attractive in cloud computing platforms for several reasons including reduced infrastructure costs, lower energy consumption and ease of management. However, the interference between co-resident workloads caused by virtualization can violate the service level objectives (SLOs) that the cloud platform guarantees. Existing solutions to minimize interference between virtual machines (VMs) are mostly based on comprehensive micro-benchmarks or online training which makes them computationally intensive. In this paper, we present CloudScope, a system for diagnosing interference for multi-tenant cloud systems in a lightweight way. CloudScope employs a discrete-time Markov Chain model for the online prediction of performance interference of co-resident VMs. It uses the results to optimally (re)assign VMs to physical machines and to optimize the hypervisor configuration, e.g. the CPU share it can use, for different workloads. We have implemented CloudScope on top of the Xen hypervisor and conducted experiments using a set of CPU, disk, and network intensive workloads and a real system (MapReduce). Our results show that CloudScope interference prediction achieves an average error of 9%. The interference-aware scheduler improves VM performance by up to 10% compared to the default scheduler. In addition, the hypervisor reconfiguration can improve network throughput by up to 30%
Einstein Geometrization Philosophy and Differential Identities in PAP-Geometry
The importance of Einstein's geometrization philosophy, as an alternative to
the least action principle, in constructing general relativity (GR), is
illuminated. The role of differential identities in this philosophy is
clarified. The use of Bianchi identity to write the field equations of GR is
shown. Another similar identity in the absolute parallelism geometry is given.
A more general differential identity in the parameterized absolute parallelism
geometry is derived. Comparison and interrelationships between the above
mentioned identities and their role in constructing field theories are
discussed.Comment: LaTeX file, 17 pages, comments and criticism are welcom
Low loss waveguide-based Butler matrix with iris coupling control method for millimeterwave applications
This paper proposes a low loss 4Ă4 Butler matrix based on rectangular
waveguide cavity resonators technology for millimeterwave
beamforming network using iris coupling method. This method has
the advantage of controlling the electrical fields and the coupling factor
inside a complex medium such as waveguide cavity resonators.
The coupling factor of 6 dB for 4Ă4 Butler matrix is achieved by
tuning the iris coupling k-value between the waveguide cavity resonators.
Thus, avoiding a higher phase difference losses and component
losses at upper millimeterwave bands. To validate the proposed
method, CST software simulations are performed under several
iris coupling k-values to achieve a 6 dB coupling factor. Then,
the proposed 4Ă4 Butler matrix is 3D metal printed using selective
laser melting (SLM) technique. The measured reflection and
isolation coefficients are observed below â10 dB, with coupling
coefficients ranging between â6 and â7 dB. The phase differences
of â42.02°, 42.02°, â130.95°, and 133.3° are achieved at the outputs.
It confirmed that using this proposed method has the superiority
over the conventional microstrip and waveguide coupling
methods by a 1 dB coupling factor loss and a 3° phase difference
error
Using cyber capabilities to inform and influence
As the world evolves and becomes more technical, the need for traditional messaging techniques diminishes. The need of the military to be able to dynamically target an individual or group with specific messages in order to inform or influence grows exponentially every year. This need also increases as the United States shifts its military focus from uneducated Third World countries to countries with established infrastructure and large cyber footprints. The military must be able to use the cyber domain to inform or influence a target audience to achieve a desired effect by disseminating a message, attributable or non-attributable, through use of the Web, e-mail or social media. The ability to understand the topology of the Internet is key to targeting a specific audience and to do this an understanding of geolocation is key. To target a specific audience with a message we must understand where they are located to understand culture, customs, and language. With cyberspace quickly becoming a dominant factor in the information environment, how can the military use the cyber domain to inform or influence a target audience to achieve a desired effect by disseminating a message, either attributable or non-attributable through the web, e-mail or social mediahttp://archive.org/details/usingcybercapabi1094527908Major, United States ArmyApproved for public release; distribution is unlimited
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Storyline description of Southern Hemisphere midlatitude circulation and precipitation response to greenhouse gas forcing
As evidence of climate change strengthens, knowledge of its regional implications becomes an urgent need for decision making. Current understanding of regional precipitation changes is substantially limited by our understanding of the atmospheric circulation response to climate change, which to a high degree remains uncertain. This uncertainty is reflected in the wide spread in atmospheric circulation changes projected in multimodel ensembles, which cannot be directly interpreted in a probabilistic sense. The uncertainty can instead be represented by studying a discrete set of physically plausible storylines of atmospheric circulation changes. By mining CMIP5 model output, here we take this broader perspective and develop storylines for Southern Hemisphere (SH) midlatitude circulation changes, conditioned on the degree of global-mean warming, based on the climate responses of two remote drivers: the enhanced warming of the tropical upper troposphere and the strengthening of the stratospheric polar vortex. For the three continental domains in the SH, we analyse the precipitation changes under each storyline. To allow comparison with previous studies, we also link both circulation and precipitation changes with those of the Southern Annular Mode. Our results show that the response to tropical warming leads to a strengthening of the midlatitude westerly winds, whilst the response to a delayed breakdown (for DJF) or strengthening (for JJA) of the stratospheric vortex leads to a poleward shift of the westerly winds and the storm tracks. However, the circulation response is not zonally symmetric and the regional precipitation storylines for South America, South Africa, South Australia and New Zealand exhibit quite specific dependencies on the two remote drivers, which are not well represented by changes in the Southern Annular Mode
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