5,278 research outputs found
An Efficient Analytical Solution to Thwart DDoS Attacks in Public Domain
In this paper, an analytical model for DDoS attacks detection is proposed, in
which propagation of abrupt traffic changes inside public domain is monitored
to detect a wide range of DDoS attacks. Although, various statistical measures
can be used to construct profile of the traffic normally seen in the network to
identify anomalies whenever traffic goes out of profile, we have selected
volume and flow measure. Consideration of varying tolerance factors make
proposed detection system scalable to the varying network conditions and attack
loads in real time. NS-2 network simulator on Linux platform is used as
simulation testbed. Simulation results show that our proposed solution gives a
drastic improvement in terms of detection rate and false positive rate.
However, the mammoth volume generated by DDoS attacks pose the biggest
challenge in terms of memory and computational overheads as far as monitoring
and analysis of traffic at single point connecting victim is concerned. To
address this problem, a distributed cooperative technique is proposed that
distributes memory and computational overheads to all edge routers for
detecting a wide range of DDoS attacks at early stage.Comment: arXiv admin note: substantial text overlap with arXiv:1203.240
A Possible Nanometer-scale Computing Device Based on an Adding Cellular Automaton
We present a simple one-dimensional Cellular Automaton (CA) which has the
property that an initial state composed of two binary numbers evolves quickly
into a final state which is their sum. We call this CA the Adding Cellular
Automaton (ACA). The ACA requires only 2N two-state cells in order to add any
two N-1 bit binary numbers. The ACA could be directly realized as a wireless
nanometer-scale computing device - a possible implementation using coupled
quantum dots is outlined.Comment: 8 pages, RevTex, 3 Postscript figures. This version to appear in App.
Phys. Let
Peristaltic Transport of a Rheological Fluid: Model for Movement of Food Bolus Through Esophagus
Fluid mechanical peristaltic transport through esophagus has been of concern
in the paper. A mathematical model has been developed with an aim to study the
peristaltic transport of a rheological fluid for arbitrary wave shapes and tube
lengths. The Ostwald-de Waele power law of viscous fluid is considered here to
depict the non-Newtonian behaviour of the fluid. The model is formulated and
analyzed with the specific aim of exploring some important information
concerning the movement of food bolus through the esophagus. The analysis has
been carried out by using lubrication theory. The study is particularly
suitable for cases where the Reynolds number is small. The esophagus is treated
as a circular tube through which the transport of food bolus takes places by
periodic contraction of the esophageal wall. Variation of different variables
concerned with the transport phenomena such as pressure, flow velocity,
particle trajectory and reflux are investigated for a single wave as well as
for a train of periodic peristaltic waves. Locally variable pressure is seen to
be highly sensitive to the flow index `n'. The study clearly shows that
continuous fluid transport for Newtonian/rheological fluids by wave train
propagation is much more effective than widely spaced single wave propagation
in the case of peristaltic movement of food bolus in the esophagus.Comment: Accepted for publication in Applied Mathematics and Mechanics (AMM),
Springe
Acoustic Properties of Soybeans
Acoustic transmission and impact force response methods were investigated for classification of soybeans. The transmission method was slow and not suitable for real-time application. A polynomial was fitted to the deconvolved frequency spectrum of acoustic impulse data for soybeans. The curve fitting procedure successfully predicted the mass of each soybean. The size of soybeans was related to the bandwidth. Diseased soybeans consistently showed narrower bandwidths than healthy soybeans. The diseased and damaged soybeans had broad variations in low frequency which was quantifiable by threshholding the error of fit in the curve fitting procedure
Quantum Information and Entropy
Thermodynamic entropy is not an entirely satisfactory measure of information
of a quantum state. This entropy for an unknown pure state is zero, although
repeated measurements on copies of such a pure state do communicate
information. In view of this, we propose a new measure for the informational
entropy of a quantum state that includes information in the pure states and the
thermodynamic entropy. The origin of information is explained in terms of an
interplay between unitary and non-unitary evolution. Such complementarity is
also at the basis of the so-called interaction-free measurement.Comment: 21 pages, 3 figure
INTRINSIC MECHANISM FOR ENTROPY CHANGE IN CLASSICAL AND QUANTUM EVOLUTION
It is shown that the existence of a time operator in the Liouville space
representation of both classical and quantum evolution provides a mechanism for
effective entropy change of physical states. In particular, an initially
effectively pure state can evolve under the usual unitary evolution to an
effectively mixed state.Comment: 20 pages. For more information or comments contact E. Eisenberg at
[email protected] (internet)
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