Abstract: SIP (Session Initiation Protocol), using HTML based
call control messaging which is quite simple and efficient, is being
replaced for VoIP networks recently. As for authentication and
authorization purposes there are many approaches and considerations
for securing SIP to eliminate forgery on the integrity of SIP
messages. On the other hand Elliptic Curve Cryptography has
significant advantages like smaller key sizes, faster computations on
behalf of other Public Key Cryptography (PKC) systems that obtain
data transmission more secure and efficient. In this work a new
approach is proposed for secure SIP authentication by using a public
key exchange mechanism using ECC. Total execution times and
memory requirements of proposed scheme have been improved in
comparison with non-elliptic approaches by adopting elliptic-based
key exchange mechanism.
Abstract: Data Envelopment Analysis (DEA) is one of the most
widely used technique for evaluating the relative efficiency of a set
of homogeneous decision making units. Traditionally, it assumes that
input and output variables are known in advance, ignoring the critical
issue of data uncertainty. In this paper, we deal with the problem
of efficiency evaluation under uncertain conditions by adopting the
general framework of the stochastic programming. We assume that
output parameters are represented by discretely distributed random
variables and we propose two different models defined according to a
neutral and risk-averse perspective. The models have been validated
by considering a real case study concerning the evaluation of the
technical efficiency of a sample of individual firms operating in
the Italian leather manufacturing industry. Our findings show the
validity of the proposed approach as ex-ante evaluation technique
by providing the decision maker with useful insights depending on
his risk aversion degree.
Abstract: The effect of calcination temperature and MgO crystallite sizes on the structure and catalytic performance of TiO2 supported nano-MgO catalyst for the trans-esterification of soybean oil has been studied. The catalyst has been prepared by deposition precipitation method, characterised by XRD and FTIR and tested in an autoclave at 225oC. The soybean oil conversion after 15 minutes of the trans-esterification reaction increased when the calcination temperature was increased from 500 to 600oC and decreased with further increase in calcination temperature. Some glycerolysis activity was also detected on catalysts calcined at 600 and 700oC after 45 minutes of reaction. The trans-esterification reaction rate increased with the decrease in MgO crystallite size for the first 30 min.
Abstract: Transpedicular screw fixation in spinal fractures,
degenerative changes, or deformities is a well-established procedure.
However, important rate of fixation failure due to screw bending,
loosening, or pullout are still reported particularly in weak bone stock
in osteoporosis. To overcome the problem, mechanism of failure has
to be fully investigated in vitro. Post-mortem human subjects are less
accessible and animal cadavers comprise limitations due to different
geometry and mechanical properties. Therefore, the development of a
synthetic model mimicking the realistic human vertebra is highly
demanded. A bone surrogate, composed of Polyurethane (PU) foam
analogous to cancellous bone porous structure, was tested for 3
different densities in this study. The mechanical properties were
investigated under uniaxial compression test by minimizing the end
artifacts on specimens. The results indicated that PU foam of 0.32
g.cm-3 density has comparable mechanical properties to human
cancellous bone in terms of young-s modulus and yield strength.
Therefore, the obtained information can be considered as primary
step for developing a realistic cancellous bone of human vertebral
body. Further evaluations are also recommended for other density
groups.
Abstract: Linear stochastic estimation and quadratic stochastic
estimation techniques were applied to estimate the entire velocity
flow-field of an open cavity with a length to depth ratio of 2. The
estimations were done through the use of instantaneous velocity
magnitude as estimators. These measurements were obtained by
Particle Image Velocimetry. The predicted flow was compared
against the original flow-field in terms of the Reynolds stresses and
turbulent kinetic energy. Quadratic stochastic estimation proved to be
more superior than linear stochastic estimation in resolving the shear
layer flow. When the velocity fluctuations were scaled up in the
quadratic estimate, both the time-averaged quantities and the
instantaneous cavity flow can be predicted to a rather accurate extent.
Abstract: Spatial and mobile computing evolves. This paper
describes a smart modeling platform called “GeoSEMA". This
approach tends to model multidimensional GeoSpatial Evolutionary
and Mobile Agents. Instead of 3D and location-based issues, there
are some other dimensions that may characterize spatial agents, e.g.
discrete-continuous time, agent behaviors. GeoSEMA is seen as a
devoted design pattern motivating temporal geographic-based
applications; it is a firm foundation for multipurpose and
multidimensional special-based applications. It deals with
multipurpose smart objects (buildings, shapes, missiles, etc.) by
stimulating geospatial agents.
Formally, GeoSEMA refers to geospatial, spatio-evolutive and
mobile space constituents where a conceptual geospatial space model
is given in this paper. In addition to modeling and categorizing
geospatial agents, the model incorporates the concept of inter-agents
event-based protocols. Finally, a rapid software-architecture
prototyping GeoSEMA platform is also given. It will be
implemented/ validated in the next phase of our work.
Abstract: Nowadays, computer worms, viruses and Trojan horse
become popular, and they are collectively called malware. Those
malware just spoiled computers by deleting or rewriting important
files a decade ago. However, recent malware seems to be born to earn
money. Some of malware work for collecting personal information so
that malicious people can find secret information such as password for
online banking, evidence for a scandal or contact address which relates
with the target. Moreover, relation between money and malware
becomes more complex. Many kinds of malware bear bots to get
springboards. Meanwhile, for ordinary internet users,
countermeasures against malware come up against a blank wall.
Pattern matching becomes too much waste of computer resources,
since matching tools have to deal with a lot of patterns derived from
subspecies. Virus making tools can automatically bear subspecies of
malware. Moreover, metamorphic and polymorphic malware are no
longer special. Recently there appears malware checking sites that
check contents in place of users' PC. However, there appears a new
type of malicious sites that avoids check by malware checking sites. In
this paper, existing protocols and methods related with the web are
reconsidered in terms of protection from current attacks, and new
protocol and method are indicated for the purpose of security of the
web.
Abstract: Independent spanning trees (ISTs) provide a number of advantages in data broadcasting. One can cite the use in fault tolerance network protocols for distributed computing and bandwidth. However, the problem of constructing multiple ISTs is considered hard for arbitrary graphs. In this paper we present an efficient algorithm to construct ISTs on hypercubes that requires minimum resources to be performed.
Abstract: Cu-mesoporous TiO2 is developed for removal acid
odor cooperated with ozone assistance and online- regeneration
system with/without UV irradiation (all weather) in study. The results
showed that Cu-mesoporous TiO2 present the desirable adsorption
efficiency of acid odor without UV irradiation, due to the larger
surface area, pore sizeand the additional absorption ability provided by
Cu. In the photocatalysis process, the material structure also benefits
Cu-mesoporous TiO2 to perform the more outstanding efficiency on
degrading acid odor. Cu also postponed the recombination of
electron-hole pairs excited from TiO2 to enhance photodegradation
ability. Cu-mesoporous TiO2 could gain the conspicuous increase on
photocatalysis ability from ozone assistance, but without any benefit
on adsorption. In addition, the online regeneration procedure could
process the used Cu-mesoporous TiO2 to reinstate the adsorption
ability and maintain the photodegradtion performance, depended on
scrubbing, desorping acid odor and reducing Cu to metal state.
Abstract: Cryptography provides the secure manner of
information transmission over the insecure channel. It authenticates
messages based on the key but not on the user. It requires a lengthy
key to encrypt and decrypt the sending and receiving the messages,
respectively. But these keys can be guessed or cracked. Moreover,
Maintaining and sharing lengthy, random keys in enciphering and
deciphering process is the critical problem in the cryptography
system. A new approach is described for generating a crypto key,
which is acquired from a person-s iris pattern. In the biometric field,
template created by the biometric algorithm can only be
authenticated with the same person. Among the biometric templates,
iris features can efficiently be distinguished with individuals and
produces less false positives in the larger population. This type of iris
code distribution provides merely less intra-class variability that aids
the cryptosystem to confidently decrypt messages with an exact
matching of iris pattern. In this proposed approach, the iris features
are extracted using multi resolution wavelets. It produces 135-bit iris
codes from each subject and is used for encrypting/decrypting the
messages. The autocorrelators are used to recall original messages
from the partially corrupted data produced by the decryption process.
It intends to resolve the repudiation and key management problems.
Results were analyzed in both conventional iris cryptography system
(CIC) and non-repudiation iris cryptography system (NRIC). It
shows that this new approach provides considerably high
authentication in enciphering and deciphering processes.
Abstract: This article presents the evolution and technological changes implemented on the full scale simulators developed by the Simulation Department of the Instituto de Investigaciones Eléctricas1 (Mexican Electric Research Institute) and located at different training centers around the Mexican territory, and allows US to know the last updates, basically from the input/output view point, of the current simulators at some facilities of the electrical sector as well as the compatible industry of the electrical manufactures and industries such as Comision Federal de Electricidad (CFE*, The utility Mexican company). Tendencies of these developments and impact within the operators- scope are also presented.
Abstract: In July 1, 2007, Taiwan Stock Exchange (TWSE) on
market observation post system (MOPS) adds a new "Financial
reference database" for investors to do investment reference. This
database as a warning to public offering companies listed on the
public financial information and it original within eight targets. In
this paper, this database provided by the indicators for the application
of company financial crisis early warning model verify that the
database provided by the indicator forecast for the financial crisis,
whether or not companies have a high accuracy rate as opposed to
domestic and foreign scholars have positive results. There is use of
Logistic Regression Model application of the financial early warning
model, in which no joined back-conditions is the first model, joined it
in is the second model, has been taken occurred in the financial crisis
of companies to research samples and then business took place
before the financial crisis point with T-1 and T-2 sample data to do
positive analysis. The results show that this database provided the
debt ratio and net per share for the best forecast variables.
Abstract: In this paper, first we introduce the stable distribution, stable process and theirs characteristics. The a -stable distribution family has received great interest in the last decade due to its success in modeling data, which are too impulsive to be accommodated by the Gaussian distribution. In the second part, we propose major applications of alpha stable distribution in telecommunication, computer science such as network delays and signal processing and financial markets. At the end, we focus on using stable distribution to estimate measure of risk in stock markets and show simulated data with statistical softwares.
Abstract: The purpose of this study is to suggest energy efficient
routing for ad hoc networks which are composed of nodes with limited
energy. There are diverse problems including limitation of energy
supply of node, and the node energy management problem has been
presented. And a number of protocols have been proposed for energy
conservation and energy efficiency. In this study, the critical point of
the EA-MPDSR, that is the type of energy efficient routing using only
two paths, is improved and developed. The proposed TP-MESR uses
multi-path routing technique and traffic prediction function to increase
number of path more than 2. It also verifies its efficiency compared to
EA-MPDSR using network simulator (NS-2). Also, To give a
academic value and explain protocol systematically, research
guidelines which the Hevner(2004) suggests are applied. This
proposed TP-MESR solved the existing multi-path routing problem
related to overhead, radio interference, packet reassembly and it
confirmed its contribution to effective use of energy in ad hoc
networks.
Abstract: An Ad hoc wireless network comprises of mobile
terminals linked and communicating with each other sans the aid of
traditional infrastructure. Optimized Link State Protocol (OLSR) is a
proactive routing protocol, in which routes are discovered/updated
continuously so that they are available when needed. Hello messages
generated by a node seeks information about its neighbor and if the
latter fails to respond to a specified number of hello messages
regulated by neighborhood hold time, the node is forced to assume
that the neighbor is not in range. This paper proposes to evaluate
OLSR routing protocol in a random mobility network having various
neighborhood hold time intervals. The throughput and delivery ratio
are also evaluated to learn about its efficiency for multimedia loads.
Abstract: An important task in solving second order linear ordinary differential equations by the finite difference is to choose a suitable stepsize h. In this paper, by using the stochastic arithmetic, the CESTAC method and the CADNA library we present a procedure to estimate the optimal stepsize hopt, the stepsize which minimizes the global error consisting of truncation and round-off error.
Abstract: The lack of any centralized infrastructure in mobile ad
hoc networks (MANET) is one of the greatest security concerns in
the deployment of wireless networks. Thus communication in
MANET functions properly only if the participating nodes cooperate
in routing without any malicious intention. However, some of the
nodes may be malicious in their behavior, by indulging in flooding
attacks on their neighbors. Some others may act malicious by
launching active security attacks like denial of service. This paper
addresses few related works done on trust evaluation and
establishment in ad hoc networks. Related works on flooding attack
prevention are reviewed. A new trust approach based on the extent of
friendship between the nodes is proposed which makes the nodes to
co-operate and prevent flooding attacks in an ad hoc environment.
The performance of the trust algorithm is tested in an ad hoc network
implementing the Ad hoc On-demand Distance Vector (AODV)
protocol.
Abstract: Many studies have shown that Artificial Neural
Networks (ANN) have been widely used for forecasting financial
markets, because of many financial and economic variables are nonlinear,
and an ANN can model flexible linear or non-linear
relationship among variables.
The purpose of the study was to employ an ANN models to
predict the direction of the Istanbul Stock Exchange National 100
Indices (ISE National-100).
As a result of this study, the model forecast the direction of the
ISE National-100 to an accuracy of 74, 51%.
Abstract: Key management is a vital component in any modern security protocol. Due to scalability and practical implementation considerations automatic key management seems a natural choice in significantly large virtual private networks (VPNs). In this context IETF Internet Key Exchange (IKE) is the most promising protocol under permanent review. We have made a humble effort to pinpoint IKEv2 net gain over IKEv1 due to recent modifications in its original structure, along with a brief overview of salient improvements between the two versions. We have used US National Institute of Technology NIIST VPN simulator to get some comparisons of important performance metrics.
Abstract: This essay endeavors to read Ama Ata Aidoo-s Our Sister Killjoy with a postocolonially-inflected consciousness. It aims at demonstrating how her work could be read as a sophisticated postcolonial revision of the colonial travel narrative whereby the protagonist-s black-eyed squint operates as 'the all-seeing-eye' to subvert the historically unbroken legacy of the Orientalist ideology. It tries to demonstrate how Sissie assumes authority and voice in an act that destabilizes the traditionally established modes of western representation. It is also an investigation into how Aidoo-s text adopts processes which disengage the Eurocentric view produced by the discursive itineraries of western institutions through diverse acts of resistance and 'various strategies of subversion and appropriation'. Her counter discursive strategies of resistance are shaped up in various ways by a feminist consciousness that attempts to articulate a distinct African version of identity and preserve cultural distinctiveness.