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William L Roberts - One of the best experts on this subject based on the ideXlab platform.
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
Energy & Fuels, 2019Co-Authors: Long Jiang, Paolo Guida, Ayman El-baz, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co...
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
2019Co-Authors: Long Jiang, Paolo Guida, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, Ayman M. Elbaz, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co-flow rate increased. Energy-dispersive X-ray spectroscopy results show that these parameters also significantly influenced the evolution of cenosphere surface elemental composition. All parameters show linear effects on the surface content of C, O, and S, excluding air co-flow rate. The increase of air co-flow temperature enhanced droplet combustion; conversely, larger initial droplet size and asphaltene content inhibited droplet combustion. The nonlinear effect of air co-flow rate indicates that it has an optimum rate for falling droplet combustion, as 90 slpm based on the current experimental setup. Eventually, our study proposed the pathway of cenosphere formation during the HFO droplet combustion
Long Jiang - One of the best experts on this subject based on the ideXlab platform.
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
Energy & Fuels, 2019Co-Authors: Long Jiang, Paolo Guida, Ayman El-baz, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co...
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
2019Co-Authors: Long Jiang, Paolo Guida, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, Ayman M. Elbaz, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co-flow rate increased. Energy-dispersive X-ray spectroscopy results show that these parameters also significantly influenced the evolution of cenosphere surface elemental composition. All parameters show linear effects on the surface content of C, O, and S, excluding air co-flow rate. The increase of air co-flow temperature enhanced droplet combustion; conversely, larger initial droplet size and asphaltene content inhibited droplet combustion. The nonlinear effect of air co-flow rate indicates that it has an optimum rate for falling droplet combustion, as 90 slpm based on the current experimental setup. Eventually, our study proposed the pathway of cenosphere formation during the HFO droplet combustion
Garth D Illingworth - One of the best experts on this subject based on the ideXlab platform.
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the uvj selection of quiescent and star forming galaxies separating early and late type galaxies and isolating edge on spirals
The Astrophysical Journal, 2012Co-Authors: Shannon G Patel, B Holden, Daniel D Kelson, Marijn Franx, Arjen Van Der Wel, Garth D IllingworthAbstract:We utilize for the first time Hubble Space Telescope Advanced Camera for Surveys imaging to examine the structural properties of galaxies in the rest-frame U - V versus V - J diagram (i.e., the UVJ diagram) using a sample at 0.6 10.25). The use of the UVJ diagram as a tool to distinguish quiescent galaxies from star-forming galaxies (SFGs) is becoming more common due to its ability to separate red quiescent galaxies from reddened SFGs. Quiescent galaxies occupy a small and distinct region of UVJ color space and we find most of them to have concentrated profiles with high Sersic indices (n > 2.5) and Smooth Structure characteristic of early-type systems. SFGs populate a broad but well-defined sequence of UVJ colors and are comprised of objects with a mix of Sersic indices. Interestingly, most UVJ-selected SFGs with high Sersic indices also display Structure due to dust and star formation typical of the n < 2.5 SFGs and late-type systems. Finally, we find that the position of an SFG on the sequence of UVJ colors is determined to a large degree by the mass of the galaxy more » and its inclination. Systems that are closer to edge-on generally display redder colors and lower [O II]{lambda}3727 luminosity per unit mass as a consequence of the reddening due to dust within the disks. We conclude that the two main features seen in UVJ color space correspond closely to the traditional morphological classes of early- and late-type galaxies. « less
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the uvj selection of quiescent and star forming galaxies separating early and late type galaxies and isolating edge on spirals
arXiv: Cosmology and Nongalactic Astrophysics, 2011Co-Authors: Shannon G Patel, B Holden, Daniel D Kelson, Marijn Franx, Arjen Van Der Wel, Garth D IllingworthAbstract:We utilize for the first time HST ACS imaging to examine the structural properties of galaxies in the rest-frame U-V versus V-J diagram (i.e., the UVJ diagram) using a sample at 0.6 10.25). The use of the UVJ diagram as a tool to distinguish quiescent galaxies from star forming galaxies (SFGs) is becoming more common due to its ability to separate red quiescent galaxies from reddened SFGs. Quiescent galaxies occupy a small and distinct region of UVJ color space and we find most of them to have concentrated profiles with high Sersic indices (n>2.5) and Smooth Structure characteristic of early-type systems. SFGs populate a broad, but well-defined sequence of UVJ colors and are comprised of objects with a mix of Sersic indices. Interestingly, most UVJ-selected SFGs with high Sersic indices also display Structure due to dust and star formation typical of the n<2.5 SFGs and late-type systems. Finally, we find that the position of a SFG on the sequence of UVJ colors is determined to a large degree by the mass of the galaxy and its inclination. Systems that are closer to edge-on generally display redder colors and lower [OII]3727 luminosity per unit mass as a consequence of the reddening due to dust within the disks. We conclude that the two main features seen in UVJ color space correspond closely to the traditional morphological classes of early and late-type galaxies.
Wheeler Campbell - One of the best experts on this subject based on the ideXlab platform.
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On the Kontsevich geometry of the combinatorial Teichm\"uller space
2021Co-Authors: Andersen, Jørgen Ellegaard, Borot Gaëtan, Charbonnier Séverin, Giacchetto Alessandro, Lewański Danilo, Wheeler CampbellAbstract:For bordered surfaces S, we develop a complete parallel between the geometry of the combinatorial Teichm\"uller space $T_S^{comb}$ equipped with Kontsevich symplectic form $\omega_K$, and then the usual Weil-Petersson geometry of Teichm\"uller space $T_S$. The basis for this is an identification of $T_S^{comb}$ with a space of measured foliations with transverse boundary conditions. We equip $T_S^{comb}$ with an analog of the Fenchel-Nielsen coordinates (defined similarly as Dehn-Thurston coordinates) and show they are Darboux for $\omega_K$ (analog of Wolpert formula). We then set up the geometric recursion of Andersen-Borot-Orantin to produce mapping class group invariants functions on $T_S^{comb}$ whose integration with respect to Kontsevich volume form satisfy topological recursion. Further we establish an analog of Mirzakhani-McShane identities, and provide applications to the study of the enumeration of multicurves with respect to combinatorial lengths and Masur-Veech volumes. The formalism allows us to provide uniform and completely geometric proofs of Witten's conjecture/Kontsevich theorem and Norbury's topological recursion for lattice point count in the combinatorial moduli space, parallel to Mirzakhani's proof of her recursion for Weil-Petersson volumes. We strengthen results of Mondello and Do on the convergence of hyperbolic geometry to combinatorial geometry along the rescaling flow, allowing us to flow systematically natural constructions on the usual Teichm\"uller space to their combinatorial analogue, such as a new derivation of the piecewise linear Structure of $T_S^{comb}$ originally obtained in the work of Penner, as the limit under the flow of the Smooth Structure of $T_S$.Comment: 107 pages. v2: Section 1 explains better relations to previous works, in particular how Dehn-Thurston coordinates compare to Fenchel-Nielsen coordinates. The PL statement (Section 5) follows from Penner's 1982 PhD thesis, this article provides a different proof via the rescaling flow on Teichm\"uller (we added Remark 5.9 in that proof to take into account twisting numbers at the boundaries
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On the Kontsevich geometry of the combinatorial Teichm\"uller space
2020Co-Authors: Andersen, Jørgen Ellegaard, Borot Gaëtan, Charbonnier Séverin, Giacchetto Alessandro, Lewański Danilo, Wheeler CampbellAbstract:We study the combinatorial Teichm\"uller space and construct on it global coordinates which are analogous to the Fenchel--Nielsen coordinates on the ordinary Teichm\"uller space. We prove that these coordinates constitute global Darboux coordinates for the Kontsevich symplectic Structure on top-dimensional cells and form an atlas with piecewise linear transition functions, providing the combinatorial Teichm\"uller space with a mapping class group invariant piecewise linear Structure. We then set up the geometric recursion in the sense of Andersen--Borot--Orantin adapted to the combinatorial setting, which naturally produces mapping class group invariant functions on the combinatorial Teichm\"uller spaces. We establish a combinatorial analogue of the Mirzakhani--McShane identity fitting this framework. We move on to the study of the spine construction and the associated rescaling flow on the Teichm\"uller space. We strengthen results of Mondello and Do on the convergence of this flow. In particular, we prove convergence of hyperbolic Fenchel--Nielsen coordinates to the combinatorial ones with some uniformity. This allows us to effectively carry natural constructions on the Teichm\"uller space to their analogues in the combinatorial spaces. For instance, we obtain the piecewise linear Structure on the combinatorial Teichm\"uller space as the limit of the Smooth Structure on the Teichm\"uller space. Finally we provide a complete recursive solution to the enumeration problem of multicurves on the combinatorial Teichm\"uller space and relate it to Masur--Veech volumes and measured foliations in the combinatorial setting.Comment: 105 page
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On the Kontsevich geometry of the combinatorial Teichm\"uller space
HAL CCSD, 2020Co-Authors: Andersen, Jørgen Ellegaard, Borot Gaëtan, Charbonnier Séverin, Giacchetto Alessandro, Lewański Danilo, Wheeler CampbellAbstract:We study the combinatorial Teichm\"uller space and construct on it global coordinates which are analogous to the Fenchel--Nielsen coordinates on the ordinary Teichm\"uller space. We prove that these coordinates constitute global Darboux coordinates for the Kontsevich symplectic Structure on top-dimensional cells and form an atlas with piecewise linear transition functions, providing the combinatorial Teichm\"uller space with a mapping class group invariant piecewise linear Structure. We then set up the geometric recursion in the sense of Andersen--Borot--Orantin adapted to the combinatorial setting, which naturally produces mapping class group invariant functions on the combinatorial Teichm\"uller spaces. We establish a combinatorial analogue of the Mirzakhani--McShane identity fitting this framework. We move on to the study of the spine construction and the associated rescaling flow on the Teichm\"uller space. We strengthen results of Mondello and Do on the convergence of this flow. In particular, we prove convergence of hyperbolic Fenchel--Nielsen coordinates to the combinatorial ones with some uniformity. This allows us to effectively carry natural constructions on the Teichm\"uller space to their analogues in the combinatorial spaces. For instance, we obtain the piecewise linear Structure on the combinatorial Teichm\"uller space as the limit of the Smooth Structure on the Teichm\"uller space. Finally we provide a complete recursive solution to the enumeration problem of multicurves on the combinatorial Teichm\"uller space and relate it to Masur--Veech volumes and measured foliations in the combinatorial setting
Paolo Guida - One of the best experts on this subject based on the ideXlab platform.
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
Energy & Fuels, 2019Co-Authors: Long Jiang, Paolo Guida, Ayman El-baz, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co...
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Cenosphere Formation during Single-Droplet Combustion of Heavy Fuel Oil
2019Co-Authors: Long Jiang, Paolo Guida, Saeed M. Al-noman, Ibrahim A. Alghamdi, Saumitra Saxena, Ayman M. Elbaz, William L RobertsAbstract:The current study aims to investigate cenosphere formation during single-droplet combustion of heavy fuel oil (HFO). A droplet generator was developed to produce freely falling monodisperse droplets uniformly. With the aid of high-speed imaging, droplet diameter was verified to be well controlled within the range of 390–698 μm, and droplets spacing distance was sufficient to avoid droplet–droplet interactions. Impacts of operation conditions (initial HFO droplet size, temperature, and air co-flow rate) and asphaltene content on cenosphere formation in a drop tube furnace were then investigated. Three types of cenosphere morphology were observed by field emission scanning electron microscopy (SEM), namely, larger hollow globules, medium porous cenospheres, and smaller cenospheres with a perfectly spherical and Smooth Structure. The SEM results show that the mean diameter of collected cenospheres increased as initial droplet size and asphaltene content increased, while it decreased as temperature and air co-flow rate increased. Energy-dispersive X-ray spectroscopy results show that these parameters also significantly influenced the evolution of cenosphere surface elemental composition. All parameters show linear effects on the surface content of C, O, and S, excluding air co-flow rate. The increase of air co-flow temperature enhanced droplet combustion; conversely, larger initial droplet size and asphaltene content inhibited droplet combustion. The nonlinear effect of air co-flow rate indicates that it has an optimum rate for falling droplet combustion, as 90 slpm based on the current experimental setup. Eventually, our study proposed the pathway of cenosphere formation during the HFO droplet combustion
