2,937 research outputs found
Direct tensor expression by Eulerian approach for constitutive relations based on strain invariants in transversely isotropic green elasticity - finite extension and torsion
It has been proven by J.C.Criscione that constitutive relations(mixed approach) based
on a set of five strain invariants (Beta-1, Beta-2, Beta-3, Beta-4, Beta-5) are useful and stable for experimentally
determining response terms for transversely isotropic material. On the other
hand, Rivlin’s classical model is an unsuitable choice for determining response terms
due to the co-alignment of the five invariants (I1, I2, I3, I4, I5). Despite this, however,
a mixed (Lagrangian and Eulerian) approach causes unnecessary computational time
and requires intricate calculation in the constitutive relation. Through changing the
way to approach the derivation of a constitutive relation, we have verified that using
an Eulerian approach causes shorter computational time and simpler calculation than
using a mixed approach does. We applied this approach to a boundary value problem
under specific deformation, i.e. finite extension and torsion to a fiber reinforced circular
cylinder. The results under this deformation show that the computational time
by Eulerian is less than half of the time by mixed. The main reason for the difference
is that we have to determine two unit vectors on the cross fiber direction from the
right Cauchy Green deformation tensor at every radius of the cylinder when we use a
mixed approach. On the contrary, we directly use the left Cauchy Green deformation
tensor in the constitutive relation by the Eulerian approach without defining the two
cross fiber vectors. Moreover, the computational time by the Eulerian approach is not influenced by the degree of deformation even in the case of computational time
by the Eulerian approach, possibly becoming the same as the computational time by
the mixed approach. This is from the theoretical thought that the mixed approach
is almost the same as the Eulerian approach under small deformation. This new
constitutive relation by Eulerian approach will have more advantages with regard
to saving computational time as the deformation gets more complicated. Therefore,
since the Eulerain approach effectively shortens computational time, this may enhance
the computational tools required to approach the problems with greater degrees of
anisotropy and viscoelasticity
Andro-Simnet: Android Malware Family Classification Using Social Network Analysis
While the rapid adaptation of mobile devices changes our daily life more
conveniently, the threat derived from malware is also increased. There are lots
of research to detect malware to protect mobile devices, but most of them adopt
only signature-based malware detection method that can be easily bypassed by
polymorphic and metamorphic malware. To detect malware and its variants, it is
essential to adopt behavior-based detection for efficient malware
classification. This paper presents a system that classifies malware by using
common behavioral characteristics along with malware families. We measure the
similarity between malware families with carefully chosen features commonly
appeared in the same family. With the proposed similarity measure, we can
classify malware by malware's attack behavior pattern and tactical
characteristics. Also, we apply a community detection algorithm to increase the
modularity within each malware family network aggregation. To maintain high
classification accuracy, we propose a process to derive the optimal weights of
the selected features in the proposed similarity measure. During this process,
we find out which features are significant for representing the similarity
between malware samples. Finally, we provide an intuitive graph visualization
of malware samples which is helpful to understand the distribution and likeness
of the malware networks. In the experiment, the proposed system achieved 97%
accuracy for malware classification and 95% accuracy for prediction by K-fold
cross-validation using the real malware dataset.Comment: 13 pages, 11 figures, dataset link:
http://ocslab.hksecurity.net/Datasets/andro-simnet , demo video:
https://youtu.be/JmfS-ZtCbg4 , In Proceedings of the 16th Annual Conference
on Privacy, Security and Trust (PST), 201
Analysis of Building Energy Savings Potential for Metal Panel Curtain Wall Building by Reducing Thermal Bridges at Joints Between Panels
AbstractTo achieve national greenhouse gas reduction in the building sector, heating and cooling energy in buildings should be reduced. The government has strengthened regulations on insulation performance for building energy savings. However, the building envelope has various thermal bridges. In particular, a metal panel curtain wall comprises a number of thermal bridges at joints between the panels and the fixing units, thus degrading the overall thermal performance. To reduce building energy, it is necessary to reduce thermal bridges in building envelopes. This study aims to analyze the energy saving potential achieved by reducing thermal bridges. For this, the insulation performance and building energy needs of the existing and alternative metal panel curtain wall were evaluated. The alternative metal panel curtain wall that uses plastic molds at joints between panels and the thermally-broken brackets was suggested to reduce heat loss through thermal bridges. As results, the effective U-value of the alternative metal panel curtain wall was reduced by 72% compared with the existing metal panel curtain wall. In addition, annual heating energy needs of the alternative metal panel curtain wall building was reduced by 26%, and annual total energy needs was reduced by 6% because annual cooling energy needs of it slightly increased compared with the existing metal panel curtain wall. In conclusion, the alternative metal panel curtain wall considerably influenced the savings in building energy needs by reducing thermal bridges
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