14,214 research outputs found
Real-Time Misbehavior Detection in IEEE 802.11e Based WLANs
The Enhanced Distributed Channel Access (EDCA) specification in the IEEE
802.11e standard supports heterogeneous backoff parameters and arbitration
inter-frame space (AIFS), which makes a selfish node easy to manipulate these
parameters and misbehave. In this case, the network-wide fairness cannot be
achieved any longer. Many existing misbehavior detectors, primarily designed
for legacy IEEE 802.11 networks, become inapplicable in such a heterogeneous
network configuration. In this paper, we propose a novel real-time hybrid-share
(HS) misbehavior detector for IEEE 802.11e based wireless local area networks
(WLANs). The detector keeps updating its state based on every successful
transmission and makes detection decisions by comparing its state with a
threshold. We develop mathematical analysis of the detector performance in
terms of both false positive rate and average detection rate. Numerical results
show that the proposed detector can effectively detect both contention window
based and AIFS based misbehavior with only a short detection window.Comment: Accepted to IEEE Globecom 201
A positivity preserving scheme for Poisson-Nernst-Planck Navier-Stokes equations and its error analysis
We consider in this paper a numerical approximation of
Poisson-Nernst-Planck-Navier- Stokes (PNP-NS) system. We construct a decoupled
semi-discrete and fully discrete scheme that enjoys the properties of
positivity preserving, mass conserving, and unconditionally energy stability.
Then, we establish the well-posedness and regularity of the initial and
(periodic) boundary value problem of the PNP-NS system under suitable
assumptions on the initial data, and carry out a rigorous convergence analysis
for the fully discretized scheme. We also present some numerical results to
validate the positivity-preserving property and the accuracy of our scheme
Exploration of the Survival Probability and Shape Evolution of Crushable Particles during One-Dimensional Compression Using Dyed Gypsum Particles
Observing the fragmentation of individual particles within granular assemblies is a subject of evident theoretical and practical importance. A new technique using dyed gypsum particles (DGPs) to match the broken particles to their parents was adopted in this study. An image-based method of acquiring the shape information of particles from two orthogonal views was proposed. The mass survival probability and shape characteristics of the children particles were analyzed after a series of one-dimensional compression tests on the DGPs. It was found that medium-sized particles in the polydisperse samples underwent more breakage than the other particles, and this might have been attributed to the combined effects of the particle crushing strength and the coordination number. The shape evolution of broken particles and surviving particles showed opposite trends. Because the particles after the test within a given size range consisted of both the broken and surviving particles, their overall shape characteristics did not show a consistent trend. Furthermore, individual particle crushing tests on the children particles suggested that the breakage-induced shape irregularity did not change the Weibull modulus, but had a substantial effect on the magnitude of the survival probability
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