1,655 research outputs found
Fracture toughness in fibrous materials
In the present paper, a fiber bundle model in (1+1)-dimensions that simulates
the rupture process of a fibrous material pulled by an uniaxial force F is
analyzed. In this model the load of a broken fiber is shifted in equal portions
onto the nearest unbroken fibers. The force-displacement diagram is obtained
for several traction velocities v and temperatures t. Also, it is shown how the
fracture toughness changes with the traction velocity v and with the
temperature t. In this paper it is shown that the rupture process is strongly
dependent on temperature t and on velocity v.Comment: 4 pages, 4 figures.eps, Revte
Fluctuating Commutative Geometry
We use the framework of noncommutative geometry to define a discrete model
for fluctuating geometry. Instead of considering ordinary geometry and its
metric fluctuations, we consider generalized geometries where topology and
dimension can also fluctuate. The model describes the geometry of spaces with a
countable number of points. The spectral principle of Connes and
Chamseddine is used to define dynamics.We show that this simple model has two
phases. The expectation value , the average number of points in the
universe, is finite in one phase and diverges in the other. Moreover, the
dimension $\delta$ is a dynamical observable in our model, and plays the role
of an order parameter. The computation of is discussed and an upper
bound is found, . We also address another discrete model defined
on a fixed dimension, where topology fluctuates. We comment on a possible
spontaneous localization of topology.Comment: 7 pages. Talk at the conference "Spacetime and Fundamental
Interactions: Quantum Aspects" (Vietri sul Mare, Italy, 26-31 May 2003), in
honour of A. P. Balachandran's 65th birthda
Experimental Realization of the Fuse Model of Crack Formation
In this work, we present an experimental investigation of the fuse model. Our
main goal was to study the influence of the disorder on the fracture process.
The experimental apparatus used consisted of an square lattice with
fuses placed on each bond of the lattice. Two types of materials were used as
fuses: copper and steel wool wires. The lattice composed only by copper wires
varied from a weakly disordered system to a strongly disordered one. The
lattice formed only by steel wool wires corresponded to a strongly disordered
one. The experimental procedure consisted of applying a potential difference V
to the lattice and measuring the respective current I. The characteristic
function obtained was investigated in order to find the scaling law
dependence of the voltage and the current on the system size when the
disorder was changed. Our results show that the scaling laws are only verified
for the disordered regime.Comment: 4 pages, 8 figures.ep
Endometriosis: A Rare Cause of Large Bowel Obstruction.
Large bowel obstruction can result in significant morbidity and mortality, especially in cases of acute complete obstruction. There are many possible causes, the most common in adults being colorectal cancer. Endometriosis is a benign disease, and the most affected extragenital location is the bowel, especially the rectosigmoid junction. However, transmural involvement and acute occlusion are very rare events. We report an exceptional case of acute large bowel obstruction as the initial presentation of endometriosis. The differential diagnosis of colorectal carcinoma may be challenging, and this case emphasizes the need to consider intestinal endometriosis in females at a fertile age presenting with gastrointestinal symptoms and an intestinal mass causing complete large bowel obstruction.info:eu-repo/semantics/publishedVersio
WEB CRAWLER FOR SOCIAL NETWORK USER DATA PREDICTION USING SOFT COMPUTING METHODS
This paper addresses how elementary data from a public user profile in Instagram can be scraped and loaded into a database without any consent. Furthermore, discusses how soft computing methods such neural networks can be used to determine the popularity of a user’s post. Conclusively, raises questions about user’s privacy and how tools like this can be used for better or for wors
Identificação taxonômica de três lepidópteros em cajueiro no Brasil.
Este trabalho objetiva relatar a identificacao taxonomica de tres especies de lepidopteros, pragas do cajueiro.bitstream/CNPAT-2010/5372/1/Ct-026.pd
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