11,593 research outputs found
Platform as a service gateway for the Fog of Things
Internet of Things (IoT), one of the key research topics in recent years, together with concepts from Fog Computing, brings rapid advancements in Smart City, Monitoring Systems, industrial control, transportation and other fields. These applications require a reconfigurable sensor architecture that can span multiple scenarios, devices and use cases that allow storage, networking and computational resources to be efficiently used on the edge of the network. There are a number of platforms and gateway architectures that have been proposed to manage these components and enable application deployment. These approaches lack horizontal integration between multiple providers as well as higher order functionalities like load balancing and clustering. This is partly due to the strongly coupled nature of the deployed applications, a lack of abstraction of device communication layers as well as a lock-in for communication protocols. This is a major obstacle for the development of a protocol agnostic application environment that allows for single application to be migrated and to work with multiple peripheral devices with varying protocols from different local gateways. This research looks at existing platforms and their shortcomings as well as proposes a messaging based modular gateway platform that enables clustering of gateways and the abstraction of peripheral communication protocols. This allows applications to send and receive messages regardless of their location and destination device protocol, creating a more uniform development environment. Furthermore, it results in a more streamlined application development and testing while providing more efficient use of the gateways resources. Our evaluation of a prototype for the system shows the need for the migration of resources and the QoS advantages of such a system. The presented use-case scenarios show that clustering can prove to be an advantage in certain use-cases as well as the deployment of a larger testing and control environment through the platform
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Collaborative development of diffraction-limited beamline optical systems at US DOE light sources
An ongoing collaboration among four US Department of Energy (DOE) National Laboratories has demonstrated key technology prototypes and software modeling tools required for new high-coherent flux beamline optical systems. New free electron laser (FEL) and diffraction-limited storage ring (DLSR) light sources demand wavefront preservation from source to sample to achieve and maintain optimal performance. Fine wavefront control was achieved using a novel, roomtemperature cooled mirror system called REAL (resistive element adjustable length) that combines cooling with applied, spatially variable auxiliary heating. Single-grating shearing interferometry (also called Talbot interferometry) and Hartmann wavefront sensors were developed and used for optical characterization and alignment on several beamlines, across a range of photon energies. Demonstrations of non-invasive hard x-ray wavefront sensing were performed using a thin diamond single-crystal as a beamsplitter
Quark Orbital Angular Momentum in the Baryon
Analytical and numerical results, for the orbital and spin content carried by
different quark flavors in the baryons, are given in the chiral quark model
with symmetry breaking. The reduction of the quark spin, due to the spin
dilution in the chiral splitting processes, is transferred into the orbital
motion of quarks and antiquarks. The orbital angular momentum for each quark
flavor in the proton as a function of the partition factor and the
chiral splitting probability is shown. The cancellation between the spin
and orbital contributions in the spin sum rule and in the baryon magnetic
moments is discussed.Comment: 26 pages, 3 figures, revised version with minor eq. no and ref. no.
corrections. Discussion on the spin and a new ref. are adde
Phenomenology of quintessino dark matter -- Production of NLSP particles
In the model of quintessino as dark matter particle, the dark matter and dark
energy are unified in one superfield, where the dynamics of the Quintessence
drives the Universe acceleration and its superpartner, quintessino, makes up
the dark matter of the Universe. This scenario predicts the existence of long
lived as the next lightest supersymmetric particle. In this
paper we study the possibility of detecting produced by the high
energy cosmic neutrinos interacting with the earth matter. By a detailed
calculation we find that the event rate is one to several hundred per year at a
detector with effective area of . The study in this paper can be also
applied for models of gravitino or axino dark matter particles.Comment: 16 pages, 5 figures, a new section about NLSP stau is added,
references adde
Circuit Effect On The Current-Voltage Characteristics Of Ultrasmall Tunnel Junctions
We have used the method of generating functional in imaginary time to derive
the current-voltage characteristics of a tunnel junction with arbitrary
tunneling conductance, connected in series with an external impedance and a
voltage source. We have shown that via the renormalized charging energy and the
renormalized environment conductance, our nonperturbative expressions of the
total action can be mapped onto the corresponding perturbative formulas. This
provides a straightforward way to go beyond the perturbation theory. For the
impedance being a pure resistance, we have calculated the conductance for
various voltages and temperatures, and the results agree very well with
experiments.Comment: 10 pages including 2 figures, to appear in PR
Electronic Structure of KFeSe from First Principles Calculations
Electronic structure and magnetic properties for iron-selenide KFeSe
are studied by first-principles calculations. The ground state is stripe-like
antiferromagnetic with calculated 2.26 magnetic moment on Fe atoms; and
the , coupling strengths are calculated to be 0.038 eV and 0.029 eV.
The states around are dominated by the Fe-3d orbitals which hybridize
noticeably to the Se-4p orbitals. While the band structure of KFeSe is
similar to a heavily electron-doped BaFeAs or FeSe system, the Fermi
surface of KFeSe is much closer to \fs11 system since the electron
sheets around is symmetric with respect to - exchange. These
features, as well as the absence of Fermi surface nesting, suggest that the
parental KFeSe could be regarded as an electron over-doped 11 system
with possible local moment magnetism.Comment: accepted by Chinese Physics Letter, to appear as Chinese Physics
Letter, Vol 28, page 057402 (2011
Hadronic Production of the Doubly Charmed Baryon with Intrinsic Charm
The effects of the intrinsic charm on the hadronic production of
are studied. By taking reasonable intrinsic charm component into account, the
change of the theoretical prediction on the production of for LHC
and Tevatron is small, but in contrast it may enhance significantly for SELEX.
The reason is that the collision energy at LHC and Tevatron is so large that
the gluon-gluon fusion sub-process, which is irrelevant to intrinsic charm,
becomes dominant. But the situation for SELEX is quite different. Our numerical
results for SELEX show that by considering all the contributions from various
sub-processes, the predicted cross-section may be enhanced by a factor so big
as due to a modulating intrinsic charm being taken into account.
Therefore, the hadronic production of at SELEX may be sensitive
enough in observing the intrinsic charm inside the incident hadrons.Comment: 18 pages, 8 figures. More discussions are adde
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