271 research outputs found
On the Stress Intensity Factor of cracks emanating from circular and elliptical holes in orthotropic plates
Stress Intensity Factors (SIFs) for cracks emanating from circular holes in two-dimensional orthotropic bodies were numerically computed taking into account the effect of geometry and orthotropy. A semi-analytical expression for the correction factor was found fitting the numerical data. Finally, it was demonstrated how the same expression can be used to calculate the SIF for cracks emanating from elliptical holes once appropriate changes of variables are made
Hybrid Optical Fiber Sensor And Artificial Neural Networks System For Bioethanol Quality Control And Productivity Enhancement
Bioethanol is produced by bio-chemical process that converts sugar or biomass feedstock into ethanol. After bio-chemical process, the solution is distilled under controlled conditions of pressure and temperature, in order to obtain an ethanol-water solution. However, the ethanol concentration analysis is generally performed off-line and, sometimes, a re-distillation process becomes necessary. In this research, an optical apparatus based on Fresnel reflection has been used in combination with artificial neural networks for determination of bioethanol concentration in hydro-alcoholic solution at any temperature. The volumetric concentration and temperature effect was investigated. This intelligent system can effectively detect and update in real-time the correction of distillation parameters to reduce losses of bioethanol and also to improve the quality in a production plant.7004Buggy, S.J., Murphy, R.P., James, S.W., Tatam, R.P., Cure monitoring of a UV cured epoxy resin using a long period grating Mach-Zehnder interferometer (2007) Proceedings of SPIE, 6619, pp. 66190VChehura, E., James, S.W., Tatam, R.P., Simultaneous, independent measurement of temperature and strain using a tilted fibre Bragg grating (2007) Proceedings of SPIE, 6619, pp. 66190IChong, J.H., Shum, P., Haryono, H., Yohana, A., Rao, M.K., Lu, C., Zhu, Y., Measurements of refractive index sensitivity using long-period grating refractometer (2004) Optics Communications, 229, pp. 65-69Su, H., Huang, X.G., Fresnel-reflection-based fiber sensor for on-line measurement of solute concentration in solutions (2007) Sensors and Actuators B: Chemical, 126 (2), pp. 579-582Meneghini, C., Caron, S., Proulx, A., Émond, F., Paradis, P., Paré, C., Fougères, A., Ethanol concentration measurement by Raman spectroscopy in liquid-core microstructured optical fiber (2007) Proceedings of SPIE, 6619, pp. 66191ULiang, W., Huang, Y., Xu, Y., Lee, R.K., Yariv, A., Highly sensitive fiber Bragg grating refractive index sensors (2005) Appl. Phys. Lett, 86, p. 151122Kheshgi, H.S., Prince, R.C., Sequestration of fermentation CO2 from ethanol production (2005) Energy, 30, pp. 1865-1871Olsson, L., Hahn-Hagerdal, B., Fermentation of lignocellulosic hydrolysates for ethanol production (1996) Enzyme and Microbial Technology, 18, pp. 312-331Natural Gas and Biofuel, ANP Resolution, (36 BRand 2005). , www.anp.gov, National Agency of PetroleumTakeishi, R.T., Gusken, E., de Souza, H.G.E., Meirelles, B.M., Suzuki, C.K., Study of the temperature effects in the alcohol-gasoline blend ratio determined by optical sensor (2007) 4th Brazilian Conference of R&D in Petroleum and Gas, , Proceedings, Campinas-SP, CD-RomBishop, C.M., (1995) Neural Networks for Pattern Recognition, , Oxford: Oxford University PressChen, S., Billings, S.A., Neural networks for nonlinear dynamic system modelling and identification (1992) International Journal of Control, 56 (2), pp. 319-346Dempsey, G.L., Alt, N.L., Olson, B.A., Alig, J.S., Control sensor linearization using a microcontroller-based neuralnetwork (1997) IEEE Intern. Conf. on Computational Cybernetics and Simulation, 4 (12-15), pp. 3078-3083. , PPLin, T.K., Chang, K.C., Lin, Y.B., Active Control with Optical Fiber Sensors and Neural Networks. II: Experimental Verification (2006) Journal of Structural Engineering, 132 (8), pp. 1304-1313Lin, T.K., Chang, K.C., Chung, L.L., Lin, Y.B., Active Control with Optical Fiber Sensors and Neural Networks. I: Theoretical Analysis (2006) Journal of Structural Engineering, 132 (8), pp. 1293-1303Rumelhart, D.E., Hinton, G., Willians, R., Learning Representation by Back-Propagation Errors (1986) Parallel Distributed Processing, 323 (9), pp. 533-536Kolodner, P., Williams, H., Moe, C., Optical measurement of the soret coefficient of ethanol/water solutions (1988) J. Chem. Phys, 88 (10), pp. 6512-6524Pan, S., Saghir, M.Z., Kawaji, M., Jiang, C.G., Yan, Y., Theoretical approach to evaluate thermodiffusion in aqueous alkanol solutions (2007) J. of Chemical Physics, 126, p. 014502González-Salgado, D., Nezbeda, I., Excess properties of aqueous mixtures of methanol: Simulation versus experiment (2006) Fluid Phase Equilibria, 240 (2), pp. 161-166. , PPPandey, J.D., Vyas, V., Jain, P., Dubey, G.P., Tripathi, N., Dey, R., Speed of sound, viscosity and R.I. of multicomponent systems: Theoretical predictions from the properties of pure components (1999) J. of Mol. Liq, 81, pp. 123-133C. K.Suzuki, E. Gusken, A. C. Mercado, E. Fujiwara, E. Ono, Fiber Optics Sensing System For Liquid Fuels, INPI Patent, Prot. 018070050521, 200
Elastase-2, a tissue alternative pathway for angiotensin II generation, plays a role in circulatory sympathovagal balance in mice
In vitro and ex vivo experiments indicate that elastase-2 (ELA-2), a chymotrypsin-serine protease elastase family member 2A, is an alternative pathway for angiotensin II (Ang II) generation. However, the role played by ELA-2 in vivo is unclear. We examined ELA-2 knockout (ELA-2KO) mice compared to wild-type (WT) mice and determined whether ELA-2 played a role in hemodynamics [arterial pressure (AP) and heart rate (HR)], cardiocirculatory sympathovagal balance and baroreflex sensitivity. The variability of systolic arterial pressure (SAP) and pulse interval (PI) for evaluating autonomic modulation was examined for time and frequency domains (spectral analysis), whereas a symbolic analysis was also used to evaluate PI variability. In addition, baroreflex sensitivity was examined using the sequence method. Cardiac function was evaluated echocardiographically under anesthesia. The AP was normal whereas the HR was reduced in ELA-2KO mice (425 ± 17 vs. 512 ± 13 bpm from WT). SAP variability and baroreflex sensitivity were similar in both strains. The LF power from the PI spectrum (33.6 ± 5 vs. 51.8 ± 4.8 nu from WT) and the LF/HF ratio (0.60 ± 0.1 vs. 1.45 ± 0.3 from WT) were reduced, whereas the HF power was increased (66.4 ± 5 vs. 48.2 ± 4.8 nu from WT) in ELA-2KO mice, indicating a shift toward parasympathetic modulation of HR. Echocardiographic examination showed normal fractional shortening and an ejection fraction in ELA-2KO mice; however, the cardiac output, stroke volume, and ventricular size were reduced. These findings provide the first evidence that ELA-2 acts on the sympathovagal balance of the heart, as expressed by the reduced sympathetic modulation of HR in ELA-2KO mice
Scalar hairy black holes and solitons in asymptotically flat spacetimes
A numerical analysis shows that a class of scalar-tensor theories of gravity
with a scalar field minimally and nonminimally coupled to the curvature allows
static and spherically symmetric black hole solutions with scalar-field hair in
asymptotically flat spacetimes. In the limit when the horizon radius of the
black hole tends to zero, regular scalar solitons are found. The asymptotically
flat solutions are obtained provided that the scalar potential of the
theory is not positive semidefinite and such that its local minimum is also a
zero of the potential, the scalar field settling asymptotically at that
minimum. The configurations for the minimal coupling case, although unstable
under spherically symmetric linear perturbations, are regular and thus can
serve as counterexamples to the no-scalar-hair conjecture. For the nonminimal
coupling case, the stability will be analyzed in a forthcoming paper.Comment: 7 pages, 10 postscript figures, file tex, new postscript figs. and
references added, stability analysis revisite
The Hamiltonian formulation of General Relativity: myths and reality
A conventional wisdom often perpetuated in the literature states that: (i) a
3+1 decomposition of space-time into space and time is synonymous with the
canonical treatment and this decomposition is essential for any Hamiltonian
formulation of General Relativity (GR); (ii) the canonical treatment
unavoidably breaks the symmetry between space and time in GR and the resulting
algebra of constraints is not the algebra of four-dimensional diffeomorphism;
(iii) according to some authors this algebra allows one to derive only spatial
diffeomorphism or, according to others, a specific field-dependent and
non-covariant four-dimensional diffeomorphism; (iv) the analyses of Dirac
[Proc. Roy. Soc. A 246 (1958) 333] and of ADM [Arnowitt, Deser and Misner, in
"Gravitation: An Introduction to Current Research" (1962) 227] of the canonical
structure of GR are equivalent. We provide some general reasons why these
statements should be questioned. Points (i-iii) have been shown to be incorrect
in [Kiriushcheva et al., Phys. Lett. A 372 (2008) 5101] and now we thoroughly
re-examine all steps of the Dirac Hamiltonian formulation of GR. We show that
points (i-iii) above cannot be attributed to the Dirac Hamiltonian formulation
of GR. We also demonstrate that ADM and Dirac formulations are related by a
transformation of phase-space variables from the metric to lapse
and shift functions and the three-metric , which is not canonical. This
proves that point (iv) is incorrect. Points (i-iii) are mere consequences of
using a non-canonical change of variables and are not an intrinsic property of
either the Hamilton-Dirac approach to constrained systems or Einstein's theory
itself.Comment: References are added and updated, Introduction is extended,
Subsection 3.5 is added, 83 pages; corresponds to the published versio
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
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