20,175 research outputs found
Efficient Implementation on Low-Cost SoC-FPGAs of TLSv1.2 Protocol with ECC_AES Support for Secure IoT Coordinators
Security management for IoT applications is a critical research field, especially when taking into account the performance variation over the very different IoT devices. In this paper, we present high-performance client/server coordinators on low-cost SoC-FPGA devices for secure IoT data collection. Security is ensured by using the Transport Layer Security (TLS) protocol based on the TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 cipher suite. The hardware architecture of the proposed coordinators is based on SW/HW co-design, implementing within the hardware accelerator core Elliptic Curve Scalar Multiplication (ECSM), which is the core operation of Elliptic Curve Cryptosystems (ECC). Meanwhile, the control of the overall TLS scheme is performed in software by an ARM Cortex-A9 microprocessor. In fact, the implementation of the ECC accelerator core around an ARM microprocessor allows not only the improvement of ECSM execution but also the performance enhancement of the overall cryptosystem. The integration of the ARM processor enables to exploit the possibility of embedded Linux features for high system flexibility. As a result, the proposed ECC accelerator requires limited area, with only 3395 LUTs on the Zynq device used to perform high-speed, 233-bit ECSMs in 413 µs, with a 50 MHz clock. Moreover, the generation of a 384-bit TLS handshake secret key between client and server coordinators requires 67.5 ms on a low cost Zynq 7Z007S device
Elaborating Transition Interface Sampling Methods
We review two recently developed efficient methods for calculating rate
constants of processes dominated by rare events in high-dimensional complex
systems. The first is transition interface sampling (TIS), based on the
measurement of effective fluxes through hypersurfaces in phase space. TIS
improves efficiency with respect to standard transition path sampling (TPS)
rate constant techniques, because it allows a variable path length and is less
sensitive to recrossings. The second method is the partial path version of TIS.
Developed for diffusive processes, it exploits the loss of long time
correlation. We discuss the relation between the new techniques and the
standard reactive flux methods in detail. Path sampling algorithms can suffer
from ergodicity problems, and we introduce several new techniques to alleviate
these problems, notably path swapping, stochastic configurational bias Monte
Carlo shooting moves and order-parameter free path sampling. In addition, we
give algorithms to calculate other interesting properties from path ensembles
besides rate constants, such as activation energies and reaction mechanisms.Comment: 36 pages, 5 figure
GAN-powered Deep Distributional Reinforcement Learning for Resource Management in Network Slicing
Network slicing is a key technology in 5G communications system. Its purpose
is to dynamically and efficiently allocate resources for diversified services
with distinct requirements over a common underlying physical infrastructure.
Therein, demand-aware resource allocation is of significant importance to
network slicing. In this paper, we consider a scenario that contains several
slices in a radio access network with base stations that share the same
physical resources (e.g., bandwidth or slots). We leverage deep reinforcement
learning (DRL) to solve this problem by considering the varying service demands
as the environment state and the allocated resources as the environment action.
In order to reduce the effects of the annoying randomness and noise embedded in
the received service level agreement (SLA) satisfaction ratio (SSR) and
spectrum efficiency (SE), we primarily propose generative adversarial
network-powered deep distributional Q network (GAN-DDQN) to learn the
action-value distribution driven by minimizing the discrepancy between the
estimated action-value distribution and the target action-value distribution.
We put forward a reward-clipping mechanism to stabilize GAN-DDQN training
against the effects of widely-spanning utility values. Moreover, we further
develop Dueling GAN-DDQN, which uses a specially designed dueling generator, to
learn the action-value distribution by estimating the state-value distribution
and the action advantage function. Finally, we verify the performance of the
proposed GAN-DDQN and Dueling GAN-DDQN algorithms through extensive
simulations
Finding Apparent Horizons in Dynamic 3D Numerical Spacetimes
We have developed a general method for finding apparent horizons in 3D
numerical relativity. Instead of solving for the partial differential equation
describing the location of the apparent horizons, we expand the closed 2D
surfaces in terms of symmetric trace--free tensors and solve for the expansion
coefficients using a minimization procedure. Our method is applied to a number
of different spacetimes, including numerically constructed spacetimes
containing highly distorted axisymmetric black holes in spherical coordinates,
and 3D rotating, and colliding black holes in Cartesian coordinates.Comment: 19 pages, 13 figures, LaTex, to appear in Phys. Rev. D. Minor changes
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cuIBM -- A GPU-accelerated Immersed Boundary Method
A projection-based immersed boundary method is dominated by sparse linear
algebra routines. Using the open-source Cusp library, we observe a speedup
(with respect to a single CPU core) which reflects the constraints of a
bandwidth-dominated problem on the GPU. Nevertheless, GPUs offer the capacity
to solve large problems on commodity hardware. This work includes validation
and a convergence study of the GPU-accelerated IBM, and various optimizations.Comment: Extended paper post-conference, presented at the 23rd International
Conference on Parallel Computational Fluid Dynamics (http://www.parcfd.org),
ParCFD 2011, Barcelona (unpublished
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