4,653 research outputs found
Towards the AlexNet Moment for Homomorphic Encryption: HCNN, theFirst Homomorphic CNN on Encrypted Data with GPUs
Deep Learning as a Service (DLaaS) stands as a promising solution for
cloud-based inference applications. In this setting, the cloud has a
pre-learned model whereas the user has samples on which she wants to run the
model. The biggest concern with DLaaS is user privacy if the input samples are
sensitive data. We provide here an efficient privacy-preserving system by
employing high-end technologies such as Fully Homomorphic Encryption (FHE),
Convolutional Neural Networks (CNNs) and Graphics Processing Units (GPUs). FHE,
with its widely-known feature of computing on encrypted data, empowers a wide
range of privacy-concerned applications. This comes at high cost as it requires
enormous computing power. In this paper, we show how to accelerate the
performance of running CNNs on encrypted data with GPUs. We evaluated two CNNs
to classify homomorphically the MNIST and CIFAR-10 datasets. Our solution
achieved a sufficient security level (> 80 bit) and reasonable classification
accuracy (99%) and (77.55%) for MNIST and CIFAR-10, respectively. In terms of
latency, we could classify an image in 5.16 seconds and 304.43 seconds for
MNIST and CIFAR-10, respectively. Our system can also classify a batch of
images (> 8,000) without extra overhead
"Mariage des Maillages": A new numerical approach for 3D relativistic core collapse simulations
We present a new 3D general relativistic hydrodynamics code for simulations
of stellar core collapse to a neutron star, as well as pulsations and
instabilities of rotating relativistic stars. It uses spectral methods for
solving the metric equations, assuming the conformal flatness approximation for
the three-metric. The matter equations are solved by high-resolution
shock-capturing schemes. We demonstrate that the combination of a finite
difference grid and a spectral grid can be successfully accomplished. This
"Mariage des Maillages" (French for grid wedding) approach results in high
accuracy of the metric solver and allows for fully 3D applications using
computationally affordable resources, and ensures long term numerical stability
of the evolution. We compare our new approach to two other, finite difference
based, methods to solve the metric equations. A variety of tests in 2D and 3D
is presented, involving highly perturbed neutron star spacetimes and
(axisymmetric) stellar core collapse, demonstrating the ability to handle
spacetimes with and without symmetries in strong gravity. These tests are also
employed to assess gravitational waveform extraction, which is based on the
quadrupole formula.Comment: 29 pages, 16 figures; added more information about convergence tests
and grid setu
Constraining gamma-ray pulsar gap models with a simulated pulsar population
With the large sample of young gamma-ray pulsars discovered by the Fermi
Large Area Telescope (LAT), population synthesis has become a powerful tool for
comparing their collective properties with model predictions. We synthesised a
pulsar population based on a radio emission model and four gamma-ray gap models
(Polar Cap, Slot Gap, Outer Gap, and One Pole Caustic) normalizing to the
number of detected radio pulsars in select group of surveys. The luminosity and
the wide beams from the outer gaps can easily account for the number of Fermi
detections in 2 years of observations. The wide slot-gap beams requires an
increase by a factor of ~10 of the predicted luminosity to produce a reasonable
number of gamma-ray pulsars. Such large increases in the luminosity may be
accommodated by implementing offset polar caps. The narrow polar-cap beams
contribute at most only a handful of LAT pulsars. Standard distributions in
birth location and pulsar spin-down power (Edot) fail to reproduce the LAT
findings: all models under-predict the number of LAT pulsars with high Edot,
and they cannot explain the high probability of detecting both the radio and
gamma-ray beams at high Edot. The beaming factor remains close to 1 over 4
decades in Edot evolution for the slot gap whereas it significantly decreases
with increasing age for the outer gaps. The evolution of the slot-gap
luminosity with Edot is compatible with the large dispersion of gamma-ray
luminosity seen in the LAT data. The stronger evolution predicted for the outer
gap, which is linked to the polar cap heating by the return current, is
apparently not supported by the LAT data. The LAT sample of gamma-ray pulsars
therefore provides a fresh perspective on the early evolution of the luminosity
and beam width of the gamma-ray emission from young pulsars, calling for thin
and more luminous gaps.Comment: 23 pages, 21 figures, accepted for publication in A&
Evaluation of insulation materials and composites for use in a nuclear radiation environment, phase 2
The nuclear heating of the propellant in all of the four baseline RNS configurations studied was much lower than that of the nuclear flight module configuration with the 5000-MW NERVA analyzed previously. Although the nuclear heating has been reduced, the effect of nuclear heating on the propellant as well as the effect of nuclear heating on internal structures such as antivortex baffles, screens, and sump components cannot be neglected. In addition, it was found that the present analytical precedures were not able to predict boundary layer initiation and breakoff points with the accuracy necessary to predict propellant thermodynamic nonequilibrium (stratification) and/or mixing
Design and Implementation of an RNS-based 2D DWT Processor
No abstract availabl
On the Nature of Pulsar Radio Emission
A theory of pulsar radio emission generation, in which the observed waves are
produced directly by maser-type plasma instabilities operating at the anomalous
cyclotron-Cherenkov resonance and the Cherenkov-drift resonance , is capable of explaining the main
observational characteristics of pulsar radio emission. The instabilities are
due to the interaction of the fast particles from the primary beam and the tail
of the distribution with the normal modes of a strongly magnetized
one-dimensional electron-positron plasma. The waves emitted at these resonances
are vacuum-like, electromagnetic waves that may leave the magnetosphere
directly. In this model, the cyclotron-Cherenkov instability is responsible for
core emission pattern and the Cherenkov-drift instability produces conal
emission. The conditions for the development of the cyclotron-Cherenkov
instability are satisfied for both typical and millisecond pulsars provided
that the streaming energy of the bulk plasma is not very high . In a typical pulsar the cyclotron-Cherenkov and Cherenkov-drift resonances
occur in the outer parts of magnetosphere at . This
theory can account for various aspects of pulsar phenomenology including the
morphology of the pulses, their polarization properties and their spectral
behavior. We propose several observational tests for the theory. The most
prominent prediction are the high altitudes of the emission region and the
linear polarization of conal emission in the plane orthogonal to the local
osculating plane of the magnetic field.Comment: 39 pages, 10 figure
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