ExxonMobil

About: ExxonMobil is a company organization based out in Irving, Texas, United States. It is known for research contribution in the topics: Catalysis & Polymerization. The organization has 16969 authors who have published 23758 publications receiving 535713 citations. The organization is also known as: Exxon Mobil Corporation & Exxon Mobil Corp..

A numerical study of the laminar flame speed of stratified methane/air flames

Abstract: Freely propagating laminar methane/air flames were modeled for spatially stratified equivalence ratio conditions at atmospheric pressure. The GRI 2.11 mechanism was used with a modified version of the Lawrence Livermore National Laboratory HCT code to describe the reaction kinetics. Results showed that the laminar flame speed was strongly affected by the equivalence ratio gradient and by the burned gas composition and temperature. Production of molecular hydrogen from the original fuel and its transport to the reaction zone as well as heat transfer from the burned to the fresh gases are key factors in understanding the influence of stratification on laminar flame speed. Combinations of different mixture stratification conditions can either enhance or reduce the flame velocity when compared with homogeneous mixtures. Mixture stratification is also responsible for higher flame resistance to extinction both on the lean and rich sides of the equivalence ratio. The importance of heat and mass transfer on the observed results implies that their extrapolation to high pressure and to turbulent systems must be made with care.

Seismic velocity structure of the rifted margin of the eastern Grand Banks of Newfoundland, Canada

Abstract: [1] We present a compressional seismic velocity profile of the crust of the eastern margin of the Grand Banks of Newfoundland, Canada. This velocity model was obtained by a tomographic inversion of wide-angle data recorded on a linear array of 24 ocean bottom seismometers (OBSs). At the landward side, we imaged a crustal thickness of 27 km in Flemish Pass and beneath Beothuk Knoll, which is thinner than the 35-km-thick crust of the central Grand Banks. We therefore assume that the eastern rim of the Grand Banks stretched uniformly by 25%. Farther seaward, the continental crust tapers rapidly beneath the continental slope to ∼6 km thickness. In the distal margin we find a 60-km-wide zone with seismic velocities between 5.0 and 6.5 km s−1 that thins to the southeast from 6 to 2 km, which we interpret as highly extended continental crust. Contrary to other seismic studies of the margins of the Grand Banks, we find seismic velocities of 8 km s−1 and higher beneath this thin crustal layer in the continent-ocean transition. We conclude that mantle was locally emplaced at shallow levels without significant hydration from seawater or serpentinized mantle was removed along a decollement in the final stages of continental rifting. The outer edge of highly extended continental crust borders a 25-km-wide zone where seismic velocities increase gradually from 6.3 km s−1 just below the top of acoustic basement to 7.7 km s−1 at 5 km below basement. We interpret this area as a relatively narrow zone of exhumed and serpentinized continental mantle. Seaward, we imaged a thin and laterally heterogeneous layer with a seismic velocity that increases sharply from 5.0 km s−1 in basement ridges to 7.0 km s−1 at its base, overlying mantle velocities between 7.8 and 8.2 km s−1. We interpret this area as unroofed mantle and very thin oceanic crust that formed at an incipient, magma-starved, ultraslow spreading ridge. A comparison of the conjugate rifted margins of the eastern Grand Banks and the Iberia Abyssal Plain show that they exhibit a similar seaward progression from continental crust to mantle to oceanic crust. This indicates that before continental breakup, rifting exhumed progressively deeper sections of the continental lithosphere on both conjugate margins. A comparison between the continent-ocean transition of the Grand Banks and Flemish Cap shows that the final phase of continental rifting and the formation of the first oceanic crust required more time at the Grand Banks margin than at the southeastern margin of Flemish Cap.

Structure of Dense Sodium Di-2-Ethylsulfosuccinate/D2O/Decane Microemulsions

Abstract: Small-angle neutron scattering is used to investigate the structure of single-phase AOT (sodium di-2-ethylsulfosuccinate)/${\mathrm{D}}_{2}$O/decane microemulsions containing equal volumes of water and oil and a variable concentration of surfactant. Each scattered-neutron spectrum exhibits a pronounced interaction peak. As the volume fraction of AOT is increased from 0.18 to 0.42, the peak position shifts to larger values of $Q$, and the peak height diminishes. The spectra are consistent with an ordered droplet phase, as opposed to a bicontinuous structure.

Anomalous viscous loss in emulsions.

Abstract: We propose a model for concentrated emulsions based on the speculation that a macroscopic shear strain does not produce an affine deformation in the randomly close-packed droplet structure. The model yields an anomalous contribution to the complex dynamic shear modulus that varies as the square root of frequency. We test this prediction using a novel light scattering technique to measure the dynamic shear modulus, and directly observe the predicted behavior over six decades of frequency and a wide range of volume fractions.