1,065 research outputs found
Automatização de processos de soldadura de estruturas hiperestáticas em ligas de alumínio
Este projeto tem como objetivo a promoção da tecnologia de soldadura robotizada, avançada, e com carácter de significativo grau de transversalidade à indústria, tendo em vista o desenvolvimento de processos mais eficientes, em termos de utilização de recursos de produção, em processo de soldadura.info:eu-repo/semantics/publishedVersio
Damage localisation in beams using the ritz method and speckle shear interferometry
A novel numerical-experimental technique is developed in order to minimise some
of the difficulties exhibited by others damage localisation approaches. The present
technique relies on the computation of undamaged rotation fields using the Ritz
method and the Timoshenko beam theory, while the measurement of damaged
rotation fields is performed by speckle shear interferometry. Two damage
localisation indicators are also presented, which, instead of being based on the
second derivative of displacement fields, are based on the first spatial derivative of
rotation fields. These damage localisation indicators, the modified curvature
difference (MCD) and the modified damage index (MDI), were applied successfully
in the localisation of damage in two clamped-clamped aluminium beams.The authors greatly appreciate the financial support of FCT through Project FCT PTDC/EME-PME/102095/2008
Charge-density waves in the Hubbard chain: evidence for 4k_F instability
Charge density waves in the Hubbard chain are studied by means of
finite-temperature Quantum Monte Carlo simulations and Lanczos diagonalizations
for the ground state. We present results both for the charge susceptibilities
and for the charge structure factor at densities \rho=1/6 and 1/3; for \rho=1/2
(quarter filled) we only present results for the charge structure factor. The
data are consistent with a 4k_F instability dominating over the 2k_F one, at
least for sufficiently large values of the Coulomb repulsion, U. This can only
be reconciled with the Luttinger liquid analyses if the amplitude of the 2k_F
contribution vanishes above some U^*(\rho).Comment: RevTeX, 4 two-column pages with 7 colour figures embedded in tex
Robotic welding tests MIG standard and CMT+P in aluminum alloy 6082-T6 for optimization of penetration, cord width and reinforcement
The present article describes an experimental analysis of a robotized Gas Metal-arc
Welding (GMAW) in aluminum alloy, using Metal Inert Gas (MIG) in its transfer method variation
Standard and pulsed Cold Metal Transfer (CMT+P), developed in order to optimize the penetration
depth, width and reinforcement of the weld bead. The base metal was the aluminum alloy 6082-T6
and the filler metal was aluminum alloy 5754.info:eu-repo/semantics/publishedVersio
Optimization of robotized welding in aluminum alloys with pulsed transfer mode using the Taguchi method
In order to obtain an optimal combination of welding parameters to weld an aluminum
alloy (6082-T6) with MIG (Metal Inert Gas) it was used an L27 Taguchi orthogonal array. The array
originated 27 different combinations that gives rise to 27 welding programs for the metal pulsed
spray mode. The welds were made in aluminum bars using an industrial robot. All welds were
repeated three times to ensure string repeatability. Metallographic tests were performed on the weld
beads for measuring the width bead, penetration and reinforcement. Measurement data was
analyzed for signal/noise and analysis of variance (ANOVA). Applying the Taguchi’s method, an
optimal combination of welding parameters was reached.info:eu-repo/semantics/publishedVersio
Charge-density waves in one-dimensional Hubbard superlattices
We study the formation of charge density waves (CDW's) in one-dimensional
Hubbard superlattices, modeled by a repeated pattern of repulsive (U>0) and
free (U=0) sites. By means of Lanczos diagonalizations for the ground state, we
calculate the charge structure factor. Our results show that while the
superlattice structure affects the modulation of the charge density waves, the
periodicity can still be predicted through an effective density. We also show
that, for a fixed repulsive layer thickness, the periodicity of the CDW is an
oscillatory function of the free layer thickness.Comment: 4 pages, 4 figure
Efeitos Da Clonidina E Da Rilmenidina Sobre Os Sistemas Cardiorrespiratório E Gastrointestinal De Equinos
Clonidine and rilmenidine are drugs used in human medicine as central acting antihypertensive agents due to their actions on the alpha2-adrenoceptor and I1 imidazoline receptors in the central nervous system. Currently, clonidine is also used as a pre-anesthetic medication and in spinal anesthesia, and rilmenidine, despite the lower selectivity for alpha2-adrenergic receptors than clonidine, has also shown antinociceptive potential in experimental pain models. In this study, six horses were submitted to four treatments: R1 group (0.014 mg/kg of rilmenidine); R2 group (0.021 mg/kg of rilmenidine); Clo group (0.002 mg/kg of clonidine), and a control group. The assessment comprehended their heart and respiratory rates, systolic blood pressure and intestinal motility at basal levels and, then, 60 and 120 minutes after the oral administration of the drugs. Rilmenidine decreased heart rate on the two tested doses, which did not occur in the Clonidine treatment; slight variations in systolic blood pressure in all treatments and respiratory rate reduction in treatments with rilmenidine at 0.021 mg/ kg and clonidine at 0.002 mg/kg were also observed. Further studies with different dosages and varied administration routes are still necessary in order to elucidate more effects of these drugs on horses. © 2016, Cienc. anim. bras., Goiânia. All rights reserved.17460861
Frequency and damping of hydrodynamic modes in a trapped Bose-condensed gas
Recently it was shown that the Landau-Khalatnikov two-fluid hydrodynamics
describes the collision-dominated region of a trapped Bose condensate
interacting with a thermal cloud. We use these equations to discuss the low
frequency hydrodynamic collective modes in a trapped Bose gas at finite
temperatures. We derive a variational expressions based on these equations for
both the frequency and damping of collective modes. A new feature is our use of
frequency-dependent transport coefficients, which produce a natural cutoff by
eliminating the collisionless low-density tail of the thermal cloud. Above the
superfluid transition, our expression for the damping in trapped inhomogeneous
gases is analogous to the result first obtained by Landau and Lifshitz for
uniform classical fluids. We also use the moment method to discuss the
crossover from the collisionless to the hydrodynamic region. Recent data for
the monopole-quadrupole mode in the hydrodynamic region of a trapped gas of
metastable He is discussed. We also present calculations for the damping of
the analogous monopole-quadrupole condensate mode in the superfluid
phase.Comment: 22 pages, 10 figures, submitted to Physical Review
Reduction of blood nitric oxide levels is associated with clinical improvement of the chronic pelvic pain related to endometriosis
The objective of this prospective study was to determine the plasma levels of nitric oxide (NO) in women with chronic pelvic pain secondary to endometriosis (n=24) and abdominal myofascial pain syndrome (n=16). NO levels were measured in plasma collected before and 1 month after treatment. Pretreatment NO levels (μM) were lower in healthy volunteers (47.0±12.7) than in women with myofascial pain (64.2±5.0, P=0.01) or endometriosis (99.5±12.9, P<0.0001). After treatment, plasma NO levels were reduced only in the endometriosis group (99.5±12.9 vs 61.6±5.9, P=0.002). A correlation between reduction of pain intensity and reduction of NO level was observed in the endometriosis group [correlation = 0.67 (95%CI = 0.35 to 0.85), P<0.0001]. Reduction of NO levels was associated with an increase of pain threshold in this group [correlation = -0.53 (-0.78 to -0.14), P<0.0001]. NO levels appeared elevated in women with chronic pelvic pain diagnosed as secondary to endometriosis, and were directly associated with reduction in pain intensity and increase in pain threshold after treatment. Further studies are needed to investigate the role of NO in the pathophysiology of pain in women with endometriosis and its eventual association with central sensitization.484363369CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQSem informaçã
Pregnancy Reprograms the Epigenome of Mammary Epithelial Cells and Blocks the Development of Premalignant Lesions
Pregnancy causes a series of cellular and molecular changes in mammary epithelial cells (MECs) of female adults. In addition, pregnancy can also modify the predisposition of rodent and human MECs to initiate oncogenesis. Here, we investigate how pregnancy reprograms enhancer chromatin in the mammary epithelium of mice and influences the transcriptional output of the oncogenic transcription factor cMYC. We find that pregnancy induces an expansion of the active cis-regulatory landscape of MECs, which influences the activation of pregnancy-related programs during re-exposure to pregnancy hormones in vivo and in vitro. Using inducible cMYC overexpression, we demonstrate that post-pregnancy MECs are resistant to the downstream molecular programs induced by cMYC, a response that blunts carcinoma initiation, but does not perturb the normal pregnancy-induced epigenomic landscape. cMYC overexpression drives post-pregnancy MECs into a senescence-like state, and perturbations of this state increase malignant phenotypic changes. Taken together, our findings provide further insight into the cell-autonomous signals in post-pregnancy MECs that underpin the regulation of gene expression, cellular activation, and resistance to malignant development
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