2,510,250 research outputs found
Multi Agent Modelling: Evolution and Skull Thickness in Hominids
Within human evolution, the period of Homo Erectus is particularly interesting since in this period,
our ancestors have carried thicker skulls than the species both before and after them. There are
competing theories as to the reasons of this enlargement and its reversal. One of these is the theory
that Homo Erectus males fought for females by clubbing each other on the head. The other one says
that due to the fact that Homo Erectusâ did not cook their food at all, they had to have strong jaw
muscles attached to ridges on either side of the skull which prohibited brain and skull growth but
required the skull to be thick.
The re-thinning of the skull on the other hand might be due to the fact that a thick skull provided
poor cooling for the brain or that as hominids started using tools to cut their food and using fire to
cook it, they did not require the strong jaw muscles anymore and this trait was actually selected
against since the brain had a tendency to grow and the ridges and a thick skull were preventing this.
In this paper we simulated both the fighting and the diet as ways in which the hominid skull grew
thicker. We also added other properties such as cooperation, selfishness and vision to our agents and
analyzed their changes over generations.
Keywords: Evolution, Skull Thickness, Hominids, Multi-Agent Modeling, Genetic Algorithm
Zigzag Codes: MDS Array Codes with Optimal Rebuilding
MDS array codes are widely used in storage systems to protect data against
erasures. We address the \emph{rebuilding ratio} problem, namely, in the case
of erasures, what is the fraction of the remaining information that needs to be
accessed in order to rebuild \emph{exactly} the lost information? It is clear
that when the number of erasures equals the maximum number of erasures that an
MDS code can correct then the rebuilding ratio is 1 (access all the remaining
information). However, the interesting and more practical case is when the
number of erasures is smaller than the erasure correcting capability of the
code. For example, consider an MDS code that can correct two erasures: What is
the smallest amount of information that one needs to access in order to correct
a single erasure? Previous work showed that the rebuilding ratio is bounded
between 1/2 and 3/4, however, the exact value was left as an open problem. In
this paper, we solve this open problem and prove that for the case of a single
erasure with a 2-erasure correcting code, the rebuilding ratio is 1/2. In
general, we construct a new family of -erasure correcting MDS array codes
that has optimal rebuilding ratio of in the case of erasures,
. Our array codes have efficient encoding and decoding
algorithms (for the case they use a finite field of size 3) and an
optimal update property.Comment: 23 pages, 5 figures, submitted to IEEE transactions on information
theor
IDENTIFYING IT SOLUTIONS ON FRAUD IN ELECTRONIC TRANSACTIONS OF FUNDS FROM BANKING SYSTEM
Although we hear daily of fraud, most of them are not reported. Some reports estimated that approximately 90% of assaults are not reported outside organizations were attacked, and only some of the reports are completed by punishment.In fact, for fear of losing customers, some companies (usually banks and large corporations) prefers to fall to an understanding with attackers in exchange for preserving part of the stolen money and keeping silence. Taking into account the development and modernization of the economies of the world in the last four decades, and simultaneous this global banking development and distribution were strongly influenced by the introduction of new computer technology; in such activities new computer technology had a strong impact on providers and on consumers.IT security, fraud, electronic transactions, banking system
Diffusion Adaptation over Networks under Imperfect Information Exchange and Non-stationary Data
Adaptive networks rely on in-network and collaborative processing among
distributed agents to deliver enhanced performance in estimation and inference
tasks. Information is exchanged among the nodes, usually over noisy links. The
combination weights that are used by the nodes to fuse information from their
neighbors play a critical role in influencing the adaptation and tracking
abilities of the network. This paper first investigates the mean-square
performance of general adaptive diffusion algorithms in the presence of various
sources of imperfect information exchanges, quantization errors, and model
non-stationarities. Among other results, the analysis reveals that link noise
over the regression data modifies the dynamics of the network evolution in a
distinct way, and leads to biased estimates in steady-state. The analysis also
reveals how the network mean-square performance is dependent on the combination
weights. We use these observations to show how the combination weights can be
optimized and adapted. Simulation results illustrate the theoretical findings
and match well with theory.Comment: 36 pages, 7 figures, to appear in IEEE Transactions on Signal
Processing, June 201
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