2,826 research outputs found
Impact of Correlated Mobility on Delay-Throughput Performance in Mobile Ad-Hoc Networks
Abstract—We extend the analysis of the scaling laws of wireless ad hoc networks to the case of correlated nodes movements, which are commonly found in real mobility processes. We consider a simple version of the Reference Point Group Mobility model, in which nodes belonging to the same group are constrained to lie in a disc area, whose center moves uniformly across the network according to the i.i.d. model. We assume fast mobility conditions, and take as primary goal the maximization of pernode throughput. We discover that correlated node movements have huge impact on asymptotic throughput and delay, and can sometimes lead to better performance than the one achievable under independent nodes movements. I. INTRODUCTION AND RELATED WORK In the last few years the store-carry-forward communication paradigm, which allows nodes to physically carry buffered dat
Part time faculty’s enforcement of academic integrity policies
The research examined material on academic integrity/honor codes in higher education, faculty enforcement of honor codes, faculty perceptions of honor codes, perceptions of full time vs. part time faculty of the higher education experience, higher education leadership, honor codes in business degree programs, student course evaluations and faculty reactions to student course evaluations
Polarized Fusion. Can Polarization Help to Increase the Energy Output of Fusion Reactors?
Since more than 60 years scientists are working on the idea to produce energy from
nuclear fusion of light particles like the Hydrogen isotopes. In the meantime, the
energy output of e.g. tokamak reactors was increased by five orders and modern
experiments like JET are approaching the border for energy production. The international
ITER collaboration is preparing the first fusion reactor that will produce
about ten times more energy, compared to the energy that is needed to run the
experiment. Today, the laser-induced inertial fusion reached the same level and
experiments at the National Ignition Facility (NIF) in California, USA, demonstrate
a ratio between produced and induced energy about one at the end of 2013.1
In parallel, it is discussed since 1970 to use nuclear polarized fuel to increase the
total cross sections of the different fusion reactions.2 The energy gain of fusion reactors
does not depend linearly on the total cross section. Depending on the different
concepts for nuclear fusion, magnetic confinement or inertial fusion, the energy gain
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R. Engels & G. Ciullo
is improved above average. M. Temporal et al. have shown, e.g., that the energy
gain of laser-induced inertial fusion might be increased by a factor four, or that
the necessary laser power can be reduced by 20 %, if the nuclear fuel was polarized
before.3 The downsized laser power will reduce the costs of the corresponding
project by a reasonable amount. In addition, the differential cross sections can be
modified so that it will be possible to focus the ejectiles, e.g. the neutrons, on special
wall areas. In a tokamak this can be used to concentrate the neutron flux to special
outer parts of the blanket, where the cooling can be improved and the neutrons be
used for Tritium production via the exothermic reaction 6Li+n → 4He+t.4 At the
same time, less cooling is needed for the inner parts of the blanket that allows to
bring the magnetic field coils closer to the fusion plasma. The increased magnetic
field in the plasma will increase the energy gain additionally. Another option of
polarized fuel is a new kind of plasma diagnostic inside a tokamak. In combination
with modern Nuclear Magnetic Resonance technologies (NMR) anisotropies in the
plasma can be measured to learn more about the different plasma mode
The OLYMPUS Internal Hydrogen Target
An internal hydrogen target system was developed for the OLYMPUS experiment
at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled,
tubular cell within an aluminum scattering chamber. Hydrogen entered at the
center of the cell and exited through the ends, where it was removed from the
beamline by a multistage pumping system. A cryogenic coldhead cooled the target
cell to counteract heating from the beam and increase the density of hydrogen
in the target. A fixed collimator protected the cell from synchrotron radiation
and the beam halo. A series of wakefield suppressors reduced heating from beam
wakefields. The target system was installed within the DORIS storage ring and
was successfully operated during the course of the OLYMPUS experiment in 2012.
Information on the design, fabrication, and performance of the target system is
reported.Comment: 9 pages, 13 figure
Network Awareness of P2P Live Streaming Applications
Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work. In this paper we present large scale sets of experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal is to assess what level of "network awareness" has been embedded in the applications, i.e., what parameters mainly drive the peer selection and data exchange. By using a general framework that can be extended to other systems and metrics, we show that all applications largely base their choices on the peer bandwidth, i.e., they prefer high-bandwidth users, which is rather intuitive. Moreover, TVAnts and PPLive exhibits also a preference to exchange data among peers in the same autonomous system the peer belongs to. However, no evidence about preference versus peers in the same subnet or that are closer to the considered peer emerges. We believe that next-generation P2P live streaming applications definitively need to improve the level of network-awareness, so to better localize the traffic in the network and thus increase their network-friendliness as wel
Development of a surgical stereo endoscopic image dataset for validating 3D stereo reconstruction algorithms
In the last decades, endoscopic stereo images have been exploited to retrieve tissue surface information of the surgical site using 3D reconstruction algorithms. The application of such algorithms in Computer Assisted Surgery (CAS) tools for Minimally Invasive Surgery (MIS) requires a robust validation process in order to guarantee reliability and safety. 3D reconstruction algorithms are commonly evaluated comparing their result with respect to a reference Ground Truth (GT). However, few datasets providing endoscopic images and GT are openly available.
Considering the increasing necessity of surgical datasets, the aim of this work is the generation of an Endoscopic Abdominal Stereo (EndoAbS) dataset composed of stereo-images with associated GT for 3D stereo-reconstruction algorithm validation. To recreate the surgical scenario, a polyurethane surgical phantom abdomen was built. Images were captured with a stereo-endoscope, while for acquiring the GT a laser scanner (calibrated with respect to the stereoendoscope) was used. This dataset is openly available on-line for the benefit of the CAS community
Reality Check: Today’s Child Labor Issues in U.S. Tobacco Farming
Rebecca Ciullo's & Carrie A. Picardi's poster about child labor issues in U.S. tobacco farming
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