Abstract: It is known that symmetric encryption algorithms are
fast and easy to implement in hardware. Also elliptic curves have
proved to be a good choice for building encryption system. Although
most of the symmetric systems have been broken, we can create a
hybrid system that has the same properties of the symmetric
encryption systems and in the same time, it has the strength of
elliptic curves in encryption. As DES algorithm is considered the
core of all successive symmetric encryption systems, we modified
DES using elliptic curves and built a new DES algorithm that is hard
to be broken and will be the core for all other symmetric systems.
Abstract: Key management represents a major and the most
sensitive part of cryptographic systems. It includes key generation,
key distribution, key storage, and key deletion. It is also considered
the hardest part of cryptography. Designing secure cryptographic
algorithms is hard, and keeping the keys secret is much harder.
Cryptanalysts usually attack both symmetric and public key
cryptosystems through their key management. We introduce a
protocol to exchange cipher keys over insecure communication
channel. This protocol is based on public key cryptosystem,
especially elliptic curve cryptosystem. Meanwhile, it tests the cipher
keys and selects only the good keys and rejects the weak one.
Abstract: This paper presents a novel method for remaining
useful life prediction using the Elliptical Basis Function (EBF)
network and a Markov chain. The EBF structure is trained by a
modified Expectation-Maximization (EM) algorithm in order to take
into account the missing covariate set. No explicit extrapolation is
needed for internal covariates while a Markov chain is constructed to
represent the evolution of external covariates in the study. The
estimated external and the unknown internal covariates constitute an
incomplete covariate set which are then used and analyzed by the EBF
network to provide survival information of the asset. It is shown in the
case study that the method slightly underestimates the remaining
useful life of an asset which is a desirable result for early maintenance
decision and resource planning.
Abstract: Let p be a prime number, Fp be a finite field and t ∈ F*p= Fp- {0}. In this paper we obtain some properties of ellipticcurves Ep,t: y2= y2= x3- t2x over Fp. In the first sectionwe give some notations and preliminaries from elliptic curves. In the second section we consider the rational points (x, y) on Ep,t. Wegive a formula for the number of rational points on Ep,t over Fnp for an integer n ≥ 1. We also give some formulas for the sum of x?andy?coordinates of the points (x, y) on Ep,t. In the third section weconsider the rank of Et: y2= x3- t2x and its 2-isogenous curve Et over Q. We proved that the rank of Etand Etis 2 over Q. In the last section we obtain some formulas for the sums Σt∈F?panp,t for an integer n ≥ 1, where ap,t denote the trace of Frobenius.
Abstract: The main goal of this paper is to show a possibility, how to solve numerically elliptic boundary value problems arising in 2D linear elasticity by using the fictitious domain method (FDM) and the Total-FETI domain decomposition method. We briefly mention the theoretical background of these methods and demonstrate their performance on a benchmark.
Abstract: In this paper, we introduce a new method for elliptical
object identification. The proposed method adopts a hybrid scheme
which consists of Eigen values of covariance matrices, Circular
Hough transform and Bresenham-s raster scan algorithms. In this
approach we use the fact that the large Eigen values and small Eigen
values of covariance matrices are associated with the major and minor
axial lengths of the ellipse. The centre location of the ellipse can be
identified using circular Hough transform (CHT). Sparse matrix
technique is used to perform CHT. Since sparse matrices squeeze zero
elements and contain a small number of nonzero elements they
provide an advantage of matrix storage space and computational time.
Neighborhood suppression scheme is used to find the valid Hough
peaks. The accurate position of circumference pixels is identified
using raster scan algorithm which uses the geometrical symmetry
property. This method does not require the evaluation of tangents or
curvature of edge contours, which are generally very sensitive to
noise working conditions. The proposed method has the advantages of
small storage, high speed and accuracy in identifying the feature. The
new method has been tested on both synthetic and real images.
Several experiments have been conducted on various images with
considerable background noise to reveal the efficacy and robustness.
Experimental results about the accuracy of the proposed method,
comparisons with Hough transform and its variants and other
tangential based methods are reported.
Abstract: The Elliptic Curve Digital Signature Algorithm
(ECDSA) is the elliptic curve analogue of DSA, where it is a digital
signature scheme designed to provide a digital signature based on a
secret number known only to the signer and also on the actual
message being signed. These digital signatures are considered the
digital counterparts to handwritten signatures, and are the basis for
validating the authenticity of a connection. The security of these
schemes results from the infeasibility to compute the signature
without the private key. In this paper we introduce a proposed to
development the original ECDSA with more complexity.
Abstract: Wireless sensor networks can be used to measure and monitor many challenging problems and typically involve in monitoring, tracking and controlling areas such as battlefield monitoring, object tracking, habitat monitoring and home sentry systems. However, wireless sensor networks pose unique security challenges including forgery of sensor data, eavesdropping, denial of service attacks, and the physical compromise of sensor nodes. Node in a sensor networks may be vanished due to power exhaustion or malicious attacks. To expand the life span of the sensor network, a new node deployment is needed. In military scenarios, intruder may directly organize malicious nodes or manipulate existing nodes to set up malicious new nodes through many kinds of attacks. To avoid malicious nodes from joining the sensor network, a security is required in the design of sensor network protocols. In this paper, we proposed a security framework to provide a complete security solution against the known attacks in wireless sensor networks. Our framework accomplishes node authentication for new nodes with recognition of a malicious node. When deployed as a framework, a high degree of security is reachable compared with the conventional sensor network security solutions. A proposed framework can protect against most of the notorious attacks in sensor networks, and attain better computation and communication performance. This is different from conventional authentication methods based on the node identity. It includes identity of nodes and the node security time stamp into the authentication procedure. Hence security protocols not only see the identity of each node but also distinguish between new nodes and old nodes.
Abstract: The effect of thermally induced stress on the modal
properties of highly elliptical core optical fibers is studied in this
work using a finite element method. The stress analysis is carried out
and anisotropic refractive index change is calculated using both the
conventional plane strain approximation and the generalized plane
strain approach. After considering the stress optical effect, the modal
analysis of the fiber is performed to obtain the solutions of
fundamental and higher order modes. The modal effective index,
modal birefringence, group effective index, group birefringence, and
dispersion of different modes of the fiber are presented. For
propagation properties, it can be seen that the results depend much on
the approach of stress analysis.
Abstract: Natural gas flow contains undesirable solid particles,
liquid condensation, and/or oil droplets and requires reliable
removing equipment to perform filtration. Recent natural gas
processing applications are demanded compactness and reliability of
process equipment. Since conventional means are sophisticated in
design, poor in efficiency, and continue lacking robust, a supersonic
nozzle has been introduced as an alternative means to meet such
demands.
A 3-D Convergent-Divergent Nozzle is simulated using
commercial Code for pressure ratio (NPR) varies from 1.2 to 2. Six
different shapes of nozzle are numerically examined to illustrate the
position of shock-wave as such spot could be considered as a
benchmark of particle separation. Rectangle, triangle, circular,
elliptical, pentagon, and hexagon nozzles are simulated using Fluent
Code with all have same cross-sectional area.
The simple one-dimensional inviscid theory does not describe the
actual features of fluid flow precisely as it ignores the impact of
nozzle configuration on the flow properties. CFD Simulation results,
however, show that nozzle geometry influences the flow structures
including location of shock wave.
The CFD analysis predicts shock appearance when p01/pa>1.2 for
almost all geometry and locates at the lower area ratio (Ae/At).
Simulation results showed that shock wave in Elliptical nozzle has
the farthest distance from the throat among the others at relatively
small NPR. As NPR increases, hexagon would be the farthest. The
numerical result is compared with available experimental data and
has shown good agreement in terms of shock location and flow
structure.
Abstract: Let p be a prime number, Fpbe a finite field and let Qpdenote the set of quadratic residues in Fp. In the first section we givesome notations and preliminaries from elliptic curves. In the secondsection, we consider some properties of rational points on ellipticcurves Ep,b: y2= x3+ b2 over Fp, where b ∈ F*p. Recall that theorder of Ep,bover Fpis p + 1 if p ≡ 5(mod 6). We generalize thisresult to any field Fnp for an integer n≥ 2. Further we obtain someresults concerning the sum Σ[x]Ep,b(Fp) and Σ[y]Ep,b(Fp), thesum of x- and y- coordinates of all points (x, y) on Ep,b, and alsothe the sum Σ(x,0)Ep,b(Fp), the sum of points (x, 0) on Ep,b.
Abstract: This paper aims to perform the second law analysis of
thermodynamics on the laminar film condensation of pure saturated
vapor flowing in the direction of gravity on an ellipsoid with variable
wall temperature. The analysis provides us understanding how the
geometric parameter- ellipticity and non-isothermal wall temperature
variation amplitude “A." affect entropy generation during film-wise
condensation heat transfer process. To understand of which
irreversibility involved in this condensation process, we derived an
expression for the entropy generation number in terms of ellipticity
and A. The result indicates that entropy generation increases with
ellipticity. Furthermore, the irreversibility due to finite temperature
difference heat transfer dominates over that due to condensate film
flow friction and the local entropy generation rate decreases with
increasing A in the upper half of ellipsoid. Meanwhile, the local
entropy generation rate enhances with A around the rear lower half of
ellipsoid.
Abstract: Polynomial bases and normal bases are both used for
elliptic curve cryptosystems, but field arithmetic operations such as
multiplication, inversion and doubling for each basis are implemented
by different methods. In general, it is said that normal bases, especially
optimal normal bases (ONB) which are special cases on normal bases,
are efficient for the implementation in hardware in comparison with
polynomial bases. However there seems to be more examined by
implementing and analyzing these systems under similar condition. In
this paper, we designed field arithmetic operators for each basis over
GF(2233), which field has a polynomial basis recommended by SEC2
and a type-II ONB both, and analyzed these implementation results.
And, in addition, we predicted the efficiency of two elliptic curve
cryptosystems using these field arithmetic operators.
Abstract: This paper presented the results of an experimental
investigation into the axial fatigue behavior of a 5086 aluminum
alloy which have several notch-aspect ratios a0/c0 and notch
thickness ratio a/t with semi-elliptical surface cracks. Tests were
conducted in la b air for stress levels of 50 % of their yield
strength. Experiments were carried out for various notch to
thickness ratios. Crack growth rates of test specimens both in
surface and depth directions were determined by using die
penetration method. Fuzzy Logic method was used to predict the
deep direction crack growth because the dept of the crack is
considerably difficult to measure.
Abstract: This paper reports on the results of experimental investigations on the performance of a jet pump operated under selected primary flows to optimize the related parameters. For this purpose a two-phase flow jet pump was used employing various profiles of nozzles as the primary device which was designed, fabricated and used along with the combination of mixing tube and diffuser. The profiles employed were circular, conical, and elliptical. The diameter of the nozzle used was 4 mm. The area ratio of the jet pump was 0.16. The test facility created for this purpose was an open loop continuous circulation system. Performance of the jet pump was obtained as iso-efficiency curves on characteristic curves drawn for various water flow rates. To perform the suction capability, evacuation test was conducted at best efficiency point for all the profiles.
Abstract: The major building block of most elliptic curve cryptosystems
are computation of multi-scalar multiplication. This paper
proposes a novel algorithm for simultaneous multi-scalar multiplication,
that is by employing addition chains. The previously known
methods utilizes double-and-add algorithm with binary representations.
In order to accomplish our purpose, an efficient empirical
method for finding addition chains for multi-exponents has been
proposed.
Abstract: Steel made pipelines with different diameters are used
for transmitting oil and gas which in many cases are buried in soil
under the sea bed or immersed in sea water. External corrosion of
pipes is an important form of deterioration due to the aggressive
environment of sea water. Corrosion normally results in pits. Hence,
using the finite element method, namely ABAQUS software, this
paper estimates the amount of pressure capacity reduction of a pipecontaining
a semi-elliptical pitting corrosion and the rate of corrosion
during the pipeline life of 25 years.
Abstract: The effect of wood vinegar, entomopathogenic
nematodes ((Steinernema thailandensis n. sp.) and fermented organic
substances from four plants such as: Derris elliptica Roxb, Stemona
tuberosa Lour, Tinospora crispa Mier and Azadirachta indica J. were
tested on the five varieties of sweetpotato with potential for
bioethanol production ie. Taiwan, China, PROC No.65-16, Phichit
166-5, and Phichit 129-6. The experimental plots were located at
Faculty of Agriculture, Natural Resources and Environment,
Naresuan University, Phitsanulok, Thailand. The aim of this study
was to compare the efficiency of the five treatments for growth, yield
and insect infestation on the five varieties of sweetpotato. Treatment
with entomopathogenic nematodes gave the highest average weight
of sweetpotato tubers (1.3 kg/tuber), followed by wood vinegar,
fermented organic substances and mixed treatment with yields of
0.88, 0.46 and 0.43 kg/tuber, respectively. Also the
entomopathogenic nematode treatment gave significantly higher
average width and length of sweet potato (9.82 cm and 9.45 cm,
respectively). Additionally, the entomopathogenic nematode
provided the best control of insect infestation on sweetpotato leaves
and tubers. Comparison among the varieties of sweetpotato, PROC
NO.65-16 showed the highest weight and length. However, Phichit
129-6 gave significantly higher weight of 0.94 kg/tuber. Lastly, the
lowest sweet potato weevil infestation on leaves and tubers occurred
on Taiwan and Phichit 129-6.
Abstract: The development of shape and size of a crack in a
pressure vessel under uniaxial and biaxial loadings is important in
fitness-for-service evaluations such as leak-before-break. In this
work finite element modelling was used to evaluate the mean stress
and the J-integral around a front of a surface-breaking crack. A
procedure on the basis of ductile tearing resistance curves of high and
low constrained fracture mechanics geometries was developed to
estimate the amount of ductile crack extension for surface-breaking
cracks and to show the evolution of the initial crack shape. The
results showed non-uniform constraint levels and crack driving forces
around the crack front at large deformation levels. It was also shown
that initially semi-elliptical surface cracks under biaxial load
developed higher constraint levels around the crack front than in
uniaxial tension. However similar crack shapes were observed with
more extensions associated with cracks under biaxial loading.
Abstract: Simulations of magnetic microstructure in elliptical
Permalloy elements used for controlled motion of magnetic particles
are discussed. The saturating field of the elliptical elements was
studied with respect to lateral dimensions for one-vortex, cross-tie,
diamond and double-diamond states as initial zero-field domain
configurations. With aspect ratio of 1:3 the short axis was varied
from 125 nm to 1000 nm, whereas the thickness was kept constant at
50 nm.