10,527 research outputs found
Hierarchical Design Based Intrusion Detection System For Wireless Ad hoc Network
In recent years, wireless ad hoc sensor network becomes popular both in civil
and military jobs. However, security is one of the significant challenges for
sensor network because of their deployment in open and unprotected environment.
As cryptographic mechanism is not enough to protect sensor network from
external attacks, intrusion detection system needs to be introduced. Though
intrusion prevention mechanism is one of the major and efficient methods
against attacks, but there might be some attacks for which prevention method is
not known. Besides preventing the system from some known attacks, intrusion
detection system gather necessary information related to attack technique and
help in the development of intrusion prevention system. In addition to
reviewing the present attacks available in wireless sensor network this paper
examines the current efforts to intrusion detection system against wireless
sensor network. In this paper we propose a hierarchical architectural design
based intrusion detection system that fits the current demands and restrictions
of wireless ad hoc sensor network. In this proposed intrusion detection system
architecture we followed clustering mechanism to build a four level
hierarchical network which enhances network scalability to large geographical
area and use both anomaly and misuse detection techniques for intrusion
detection. We introduce policy based detection mechanism as well as intrusion
response together with GSM cell concept for intrusion detection architecture.Comment: 16 pages, International Journal of Network Security & Its
Applications (IJNSA), Vol.2, No.3, July 2010. arXiv admin note: text overlap
with arXiv:1111.1933 by other author
Role of Mothers\u27 Nutritional Knowledge, Nutritional Factors on the School Performance
A cross sectional study was carried out to investigate the effects of mothers\u27 nutritional knowledge, health and nutritional factors and socio-economic parameters on school performance among class five students of University Laboratory School, Dhaka. All of the eighty students were selected for this study. This study found there is a strong relationship between mother\u27s knowledge score and school performance. It was found that mothers\u27 knowledge score was responsible for 91.1 percent change in school performance. The mean BMI of the mothers was 20.44. We found that the school performance measured by class roll number of the students is significantly related with mothers BMI. There was an imperfect negative association between socio-economic parameters and school performance. But the relationship between the school performances with socio-economic parameters was strongly significant. This study also observed the relationship between Individual Dietary Diversity Score (IDDS) of respondent and marks achieved in class 4 final exam. It is alarming that consumption percentage were low for eggs (30) and milk and milk products (37.5), but majority of the students who consumed milk and milk products (63.3%) and eggs (66.7%) got the highest marks
Algorithms to Compute the Lyndon Array
We first describe three algorithms for computing the Lyndon array that have
been suggested in the literature, but for which no structured exposition has
been given. Two of these algorithms execute in quadratic time in the worst
case, the third achieves linear time, but at the expense of prior computation
of both the suffix array and the inverse suffix array of x. We then go on to
describe two variants of a new algorithm that avoids prior computation of
global data structures and executes in worst-case n log n time. Experimental
evidence suggests that all but one of these five algorithms require only linear
execution time in practice, with the two new algorithms faster by a small
factor. We conjecture that there exists a fast and worst-case linear-time
algorithm to compute the Lyndon array that is also elementary (making no use of
global data structures such as the suffix array)
Loss functions, utility functions and Bayesian sample size determination.
PhDThis thesis consists of two parts. The purpose of the first part of the research is
to obtain Bayesian sample size determination (SSD) using loss or utility function
with a linear cost function. A number of researchers have studied the Bayesian SSD
problem. One group has considered utility (loss) functions and cost functions in
the SSD problem and others not. Among the former most of the SSD problems are
based on a symmetrical squared error (SE) loss function. On the other hand, in
a situation when underestimation is more serious than overestimation or vice-versa,
then an asymmetric loss function should be used. For such a loss function how
many observations do we need to take to estimate the parameter under study? We
consider different types of asymmetric loss functions and a linear cost function for
sample size determination. For the purposes of comparison, firstly we discuss the
SSD for a symmetric squared error loss function. Then we consider the SSD under
different types of asymmetric loss functions found in the literature. We also introduce
a new bounded asymmetric loss function and obtain SSD under this loss function.
In addition, to estimate a parameter following a particular model, we present some
theoretical results for the optimum SSD problem under a particular choice of loss
function. We also develop computer programs to obtain the optimum SSD where the
analytic results are not possible.
In the two parameter exponential family it is difficult to estimate the parameters
when both are unknown. The aim of the second part is to obtain an optimum decision
for the two parameter exponential family under the two parameter conjugate
utility function. In this case we discuss Lindley’s (1976) optimum decision for one
6
parameter exponential family under the conjugate utility function for the one parameter
exponential family and then extend the results to the two parameter exponential
family. We propose a two parameter conjugate utility function and then lay out the
approximation procedure to make decisions on the two parameters. We also offer a
few examples, normal distribution, trinomial distribution and inverse Gaussian distribution
and provide the optimum decisions on both parameters of these distributions
under the two parameter conjugate utility function
Structural, elastic, and electronic properties of newly discovered Li2PtSi3 superconductor: Effect of transition metals
First-principles calculations within the density functional theory (DFT) with
GGA-PBE exchange-correlation scheme have been employed to predict the
structural, the elastic and the electronic properties of newly discovered
lithium silicide superconductor, Li2PtSi3, for the first time. All the
theoretical results are compared with those calculated recently for
isostructural Li2IrSi3. The present study sheds light on the effect of
replacement of transition metal element Ir with Pt on different mechanical,
electronic, and superconducting properties. The effect of spin-orbit coupling
on electronic band structure was found to be insignificant for Li2PtSi3. The
difference in superconducting transition temperatures of Li2PtSi3 and Li2IrSi3
arises primarily due to the difference in electronic energy density of states
at the Fermi level. Somewhat reduced Debye temperature in Li2PtSi3 plays a
minor role. We have discussed the implications of the theoretical results in
details in this study.Comment: Submitted for publicatio
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