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Author Cruz, J.J.; Escudero, F.; Alvarez, E.; da Silva, L.F.F.; Carvajal, G.; Thomsen, M.; Fuentes, A.
Title Three-wavelength broadband soot pyrometry technique for axisymmetric flames Type
Year 2021 Publication Optics Letters Abbreviated Journal Opt. Lett.
Volume 46 Issue 11 Pages 2654-2657
Keywords VOLUME FRACTION; DIFFUSION FLAMES; TEMPERATURE; ABSORPTION; ETHYLENE
Abstract Soot temperature measurements in laminar flames are often performed through two-color broadband emission pyrometry (BEMI) or modulated absorption/emission (BMAE) techniques, using models to relate the ratio between flame intensities at two different wavelengths with soot temperature. To benefit from wider spectral range and increase the accuracy of experimental estimation of soot temperature, this work proposes a new approach that uses three-color broadband images captured with a basic color camera. The methodology is first validated through simulations using numerically generated flames from the CoFlame code and then used to retrieve soot temperature in an experimental campaign. The experimental results show that using three-color and BEMI provides smoother reconstruction of soot temperature than two-color and BMAE when small disturbances exist in the measured signals due to a reduced experimental noise effect. A sensitivity analysis shows that the retrieved temperature from three-color BEMI is more resilient to variations on the ratio of measured signals than BMAE, which is confirmed by an error propagation analysis based on a Monte Carlo approach.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0146-9592 ISBN Medium
Area Expedition Conference
Notes WOS:000658132700025 Approved
Call Number UAI @ alexi.delcanto @ Serial 1413
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Author Grigioni, I.; Polo, A.; Dozzi, M.V.; Stamplecoskie, K.G.; Jara, D.H.; Kamat, P.V.; Selli, E.
Title Enhanced Charge Carrier Separation in WO3/BiVO4 Photoanodes Achieved via Light Absorption in the BiVO4 Layer Type
Year 2022 Publication ACS Applied Energy Materials Abbreviated Journal ACS Appl. Energy Mater.
Volume 5 Issue 11 Pages 1314213148
Keywords solar water oxidation; heterojunction; ultrafast transient absorption; photoactive layer thickness; filter effect
Abstract Photoelectrochemical (PEC) water splitting converts solar light and water into oxygen and energy-rich hydrogen. WO3/BiVO4 heterojunction photoanodes perform much better than the separate oxide components, though internal charge recombination undermines their PEC performance when both oxides absorb light. Here we exploit the BiVO4 layer to sensitize WO3 to visible light and shield it from direct photoexcitation to overcome this efficiency loss. PEC experiments and ultrafast transient absorption spectroscopy performed by frontside (through BiVO4) or backside (through WO3) irradiating photoanodes with different BiVO4 layer thickness demonstrate that irradiation through BiVO4 is beneficial for charge separation. Optimized electrodes irradiated through BiVO4 show 40% higher photocurrent density compared to backside irradiation.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2574-0962 ISBN Medium
Area Expedition Conference
Notes Approved
Call Number UAI @ alexi.delcanto @ Serial 1732
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Author Moffat, R.; Jadue, C.; Beltran, J.F.; Herrera, R.
Title Experimental evaluation of geosynthetics as reinforcement for shotcrete Type
Year 2017 Publication Geotextiles And Geomembranes Abbreviated Journal Geotext. Geomembr.
Volume 45 Issue 3 Pages 161-168
Keywords Geosynthetics; Shotcrete; Geosynthetics reinforcement; Energy absorption; Shotcrete strength
Abstract One of the commonly used stabilization systems for rock tunnels is shotcrete. This fine aggregate mortar is usually reinforced for improving its tensile and shear strength. In deep tunnels, its capacity to absorb energy has been recently considered for design purposes, as large displacements of the wall are expected. Two of the most used materials of reinforcement are steel welded-wire mesh and fibers (steel or polypropylene) in the shotcrete mix. This study presents the results and discussion of an experimental test program conducted to obtain the load-deformation curves of reinforced shotcrete, according to ASTM C 1550, using geosynthetics grids and geotextiles as alternative reinforcement materials. In addition, plain shotcrete and steel welded-wire mesh reinforced shotcrete specimens are also considered in the experimental program as benchmark cases. The experimental results are analyzed in terms of maximum strength and toughness. Results show that the use of geosynthetics as a reinforcement material is a promising alternative to obtain shotcrete with energy absorption capacity comparable with the most common reinforcement materials used. (C) 2017 Elsevier Ltd. All rights reserved.
Address [Moffat, R.] Univ Adolfo Ibanez, Dept Civil Engn, Santiago, Chile, Email: ricardo.moffat@uai.cl;
Corporate Author Thesis
Publisher Elsevier Sci Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0266-1144 ISBN Medium
Area Expedition Conference
Notes WOS:000401879300004 Approved
Call Number UAI @ eduardo.moreno @ Serial 733
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Author Parot, R.; Rivera, J.I.; Reszka, P.; Torero, J.L.; Fuentes, A.
Title A simplified analytical model for radiation dominated ignition of solid fuels exposed to multiple non-steady heat fluxes Type
Year 2022 Publication Combustion and Flame Abbreviated Journal Combust. Flame
Volume 237 Issue Pages 111866
Keywords Ignition delay time; Fire safety; Integral heat equation; Solid ignition; Translucent solids; In-depth absorption of radiation
Abstract Heat fluxes from fires are strongly time-dependent. Historically, the thermal ignition theory in its classical form has neglected this time dependency until recent years, where theories have been developed to include time-varying incident heat fluxes. This article proposes a simplified general model formulation for the heating of solid fuels exposed to four different heat flux behaviors, considering the penetration of radiation into the medium. The incident heat flux cases developed where: Constant, Linear, Exponential and Polynomial, which represent different situations related to structural and wildland fires. The analytical models consider a spatially averaged medium temperature and exact and approximate solutions are presented, based on the critical ignition temperature criterion, which are valid for solids of any optical thickness. The results were validated by comparison with various models presented in the literature, where the model granted in this work was capable to adjust to all of them, especially when high heat fluxes are involved. Therefore, the proposed model acquires a significant engineering utility since it provides a single model to be used as a general and versatile tool to predict the ignition delay time in a manageable way for solid fuels exposed to different fire conditions.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0010-2180 ISBN Medium
Area Expedition Conference
Notes WOS:000735880500007 Approved
Call Number UAI @ alexi.delcanto @ Serial 1521
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Author Rao, B.V.B.; Jena, M.; Aepuru, R.; Udayabhaskar, R.; Mangalaraja, R.V.; Espinoza-Gonzalez, R.; Kale, S.N.
Title Superior electromagnetic wave absorption performance of Fe3O4 modified graphene assembled porous carbon (mGAPC) based hybrid foam Type
Year 2022 Publication Materials Chemistry and Physics Abbreviated Journal Mater. Chem. Phys.
Volume 290 Issue Pages 126512
Keywords Fe3O4, modified graphene assembled porous carbon (mGAPC); Reflection loss (RL); Electromagnetic wave absorption (EA)
Abstract High performance Fe3O4 modified graphene assembled porous carbon (mGAPC) based epoxy paint coated on Polyethylene (PE) foam is realized by spray technique to fabricate light weight electromagnetic absorbers. The mGAPC as a pigment in a standard composition of commercial paint was optimized and the influence of solvent and additives are studied to achieve X-band (8.2-12.4 GHz) electromagnetic wave absorption (EA) in the hybrid foam (HF). From the comparative studies, the hybrid foams obtained from epoxy paint with toluene as solvent (without Mn-octate as additive) showed a Reflection Loss (RL) -19 dB (in the range of 8.3-8.7 GHz), which was further increased with the coating cycles up to -43 dB (in 10.2-11.2 GHz).The observed rise is attributed to increase in localized interfacial polarization that arises at the combined interfaces of mGAPC. The result showed 99% loss, which projects a promising EA paint for practical applications. Further thickness dependent studies of EA in Paint Coat HF1, reveals that with increasing thickness from 0.3 to 2 mm, the RL also increases from -19 to -43 dB with changing absorption band. The superior EA properties are correlated to the percolation threshold, pigment dispersibility and further correlated to the strong absorption, destructive interference, multiple internal reflections and interfacial polarization of the radiation in the hybrid foam. Moreover, considering the paint lowest thickness similar to 0.3 mm with -19 dB of RL, the hybrid foam promises a cost-effective, fine, light-weight EA/ RL material for secure electronic devices and packaging in civil and defence applications.
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Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0254-0584 ISBN Medium
Area Expedition Conference
Notes WOS:000863104600005 Approved
Call Number UAI @ alexi.delcanto @ Serial 1677
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Author Thomsen, M.C.; Fuentes, A.; Demarco, R.; Volkwein, C.; Consalvi, J.L.; Reszka, P.
Title Soot measurements in candle flames Type
Year 2017 Publication Experimental Thermal And Fluid Science Abbreviated Journal Exp. Therm. Fluid Sci.
Volume 82 Issue Pages 116-123
Keywords MAE; Modulated Absorption/Emission; Soot volume fraction; Soot temperature; Wick effects
Abstract Soot volume fractions and soot temperatures have been measured for the first time on candle flames. Measurements on laminar steady flames were carried out using candles with wick diameters of 2, 3 and 4 mm. Wick length was varied between 4 and 10 mm. The shape of the candle flame was obtained from CH* spontaneous emissions. Measured flame heights show an increase with wick dimensions, approaching an asymptotic value for increasing wick lengths. Soot volume fractions were obtained from laser extinction measurements with the Modulated Absorption/Emission (MAE) technique. A deconvolution technique and a regularization procedure were applied to the data. Radial profiles of soot volume fractions increase when varying the wick dimensions; this effect is produced by the greater amount of fuel released by the wick. Radially integrated soot volume fractions were also calculated, presenting a similar behavior to the soot volume fraction radial profiles. The peak integrated soot volume fraction was found at approximately half the flame height, independent of the wick dimensions and burning rates. Soot temperature was obtained from emission measurements at two different wavelengths considering the attenuation of the soot particles in the optical path length. A deconvolution and regularization procedure was carried out in order to obtain temperature profiles for different heights in the flame. The observed increase in soot production and soot temperature profiles was directly related to the higher burning rate experienced by the candle. The results show that peak integrated soot volume fractions are proportional to both the mass loss rates and the flame heights. (C) 2016 Elsevier Inc. All rights reserved.
Address [Thomsen, M. C.] Univ Calif Berkeley, Dept Mech Engn, Berkeley, CA 94720 USA, Email: pedro.reszka@uai.cl
Corporate Author Thesis
Publisher Elsevier Science Inc Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0894-1777 ISBN Medium
Area Expedition Conference
Notes WOS:000392769400012 Approved
Call Number UAI @ eduardo.moreno @ Serial 696
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