Surface Location (surface + location)

Distribution by Scientific Domains


Selected Abstracts


What is DMO coverage?

GEOPHYSICAL PROSPECTING, Issue 6 2000
Ralf Ferber
,Coverage' or ,fold' is defined as the multiplicity of common-midpoint (CMP) data. For CMP stacking the coverage is consistent with the number of traces sharing a common reflection point on flat subsurface reflectors. This relationship is not true for dipping reflectors. The deficiencies of CMP stacking with respect to imaging dipping events have long been overcome by the introduction of the dip-moveout (DMO) correction. However, the concept of coverage has not yet satisfactorily been updated to a ,DMO coverage' consistent with DMO stacking. A definition of constant-velocity DMO coverage will be proposed here. A subsurface reflector will be illuminated from a given source and receiver location if the time difference between the reflector zero-offset traveltime and the NMO- and DMO-corrected traveltime of the reflection event is less than half a dominant wavelength. Due to the fact that a subsurface reflector location is determined by its zero-offset traveltime, its strike and its dip, the DMO coverage also depends on these three parameters. For every surface location, the proposed DMO coverage consists of a 3D fold distribution over reflector strike, dip and zero-offset traveltime. [source]


Numerical simulation on liquid jet behavior issued into still air

HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2003
Takao Inamura
Abstract Numerical simulations have been conducted to clarify the effects of turbulence, in the onset of protrusions on liquid jet surfaces. The turbulences in the liquid jet were simulated by the Rankin vortices. The liquid jet surface was tracked numerically by the VOF method. From numerical simulations, the protrusions on the liquid jet surface are induced by the vortices in the liquid, whose rotational direction decelerates the jet surface. Despite the distance between vortices, the displacement of the liquid jet surface from the initial surface location increases linearly, in time, at almost the same growth rate. In the initial region, the growth rate of the displacement increases as the major semiaxis-to-minor semiaxis ratio of the ellipsoidal vortex increases. The initial growth rate of displacement is almost proportional to the vortex intensity. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(2): 141,152, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10078 [source]


Self-Assembled Pb Nanostructures on Si(111) Surfaces: From Nanowires to Nanorings

ADVANCED MATERIALS, Issue 45 2009
Rui Wu
Abstract A template-directed growth method for metals is described in which ordered arrays of super-long single-crystalline metal nanowires with atomic-level-controlled width, thickness (height), and surface location are prepared by molecular beam epitaxy. Their subsequent examination by in situ scanning tunneling microscopy is also outlined. A phase-separated stripe pattern composed of alternately a Ge-rich incommensurate phase and a ,3,×,,3 phase is first obtained by Ge deposition on Si(111) substrates. Further deposition of Pb on this patterned surface leads to a well-ordered array of super-long Pb nanowires. Using the same mechanism, superconducting Pb nanorings can also be fabricated. In this review of our recent work, these Pb single-crystalline nanowires and nanorings are shown to serve as an ideal platform for the study of superconductivity in reduced dimensionalities. Furthermore, because the widths and spatial distributions of two phases can be precisely controlled by the Ge coverage and substrate temperature, and because a metal will always selectively nucleate on one of two phases, this template-directed growth method can be applied to a wide range of metals. [source]


Morphology of Polymer/Clay Latex Particles Synthesized by Miniemulsion Polymerization: Modeling and Experimental Results

MACROMOLECULAR REACTION ENGINEERING, Issue 6-7 2010
Matej Mi
Abstract BA/MMA (90:10,wt.-%) were copolymerized in the presence of two different organomodified clays (C30B and CMA16) and 1.6,2.6,wbm.-% surfactants. The effect of the compatibility of the organoclay in the monomer mixture on the morphology of hybrid polymer/clay particles was determined using TEM. The resulting morphologies were compared with the prediction of a Monte-Carlo simulation that determined the equilibrium morphology of monomer/clay hybrid miniemulsion droplets. The model predicted encapsulated morphologies only when the organoclay presented low clay/monomer and high clay/water interfacial tensions. C30B and CMA16 did not fulfill these conditions and provided a preferential surface location of the platelets on the polymer/water interphase as predicted by the model. [source]


Thermal characterisation of active layer across a soil moisture gradient in the McMurdo Dry Valleys, Antarctica

PERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2009
Scott J. Ikard
Abstract Heat transport into active layer soils is important to understanding potential responses to changes in surface energy balance, particularly in the context of changing climate. Here we present results of a study to characterise soil thermal properties along a soil moisture gradient adjacent to Lake Fryxell in Taylor Valley, Antarctica. Our goals were to characterise the thermal characteristics of these relatively wet soils (compared to the rest of the McMurdo Dry Valleys landscape), and to assess the response of the active layer to possible increases in soil moisture. We measured subsurface temperatures at depths from 3 to 50,cm at four locations along a natural gradient of wet to dry soils adjacent to Lake Fryxell from January 2006 to January 2007. We used a numerical model to estimate apparent thermal diffusivity (ATD) and simulate observed temperature time series. Calculations of ATD at discrete locations yielded values ranging from 1.0,×,10,9 , 2.4,×,10,5,m2,s,1, and the corresponding range of bulk (i.e. depth averaged at a single surface location) ATD was 2.9,×,10,9,1.2,×,10,7,m2,s,1. Thawed soils had a range of bulk ATD during warming of 2.9,×,10,9,3.8,×,10,8,m2,s,1, and during cooling of 2.9,×,10,9,4.8,×,10,8,m2,s,1. When soils were frozen, however, the range of bulk ATD was 7.6,×,10,9,1.2,×,10,7,m2,s,1 during warming, and 7.8,×,10,9,1.1,×,10,7,m2,s,1 during cooling. Estimated bulk ATD values were consistently greater in locations of enhanced soil moisture, so lakeside soils were more likely to conduct energy into the subsurface. Increased soil moisture across the landscape would likely increase ATD, allowing for greater heat exchange between the atmosphere and the subsurface. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Combined seismic tomographic and ultrashallow seismic reflection study of an Early Dynastic mastaba, Saqqara, Egypt

ARCHAEOLOGICAL PROSPECTION, Issue 4 2005
Mohamed Metwaly
Abstract Mastabas were large rectangular structures built for the funerals and burials of the earliest Pharaohs. One such mastaba was the basic building block that led to the first known stone pyramid, the,>4600-year old Step Pyramid within the Saqqara necropolis of Egypt. We have tested a number of shallow geophysical techniques for investigating in a non-invasive manner the subsurface beneath a large Early Dynastic mastaba located close to the Step Pyramid. After discovering that near-surface sedimentary rocks with unusually high electrical conductivities precluded the use of the ground-penetrating radar method, a very high-resolution seismic data set was collected along a profile that extended the 42.5,m length of the mastaba. A sledgehammer source was used every 0.2,m and the data were recorded using a 48-channel array of single geophones spaced at 0.2,m intervals. Inversions of the direct- and refracted-wave travel times provided P-wave velocity tomograms of the shallow subsurface, whereas relatively standard processing techniques yielded a high-fold (50,80) ultrashallow seismic reflection section. The tomographic and reflection images were jointly interpreted in terms of loose sand and friable limestone layers with low P-wave velocities of 150,650,m,s,1 overlying consolidated limestone and shale with velocities,>,1500,m,s,1. The sharp contact between the low- and high-velocity regimes was approximately horizontal at a depth of ca. 2,m. This contact was the source of a strong seismic reflection. Above this contact, the velocity tomogram revealed moderately high velocities at the surface location of a friable limestone outcrop and two low-velocity blocks that probably outlined sand-filled shafts. Below the contact, three regularly spaced low velocity blocks probably represented tunnels and/or subsurface chambers. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Supplementation with CoQ10 lowers age-related (ar) NOX levels in healthy subjects

BIOFACTORS, Issue 1-4 2008
Dorothy M. Morré
Our work has identified an aging-related ECTO-NOX activity (arNOX), a hydroquinone oxidase which is cell surface located and generates superoxide. This activity increases with increasing age beginning > 30 y. Because of its cell surface location and ability to generate superoxide, the arNOX proteins may serve to propagate an aging cascade both to adjacent cells and to oxidize circulating lipoproteins as significant factors determining atherogenic risk. The generation of superoxide by arNOX proteins is inhibited by Coenzyme Q10 as one basis for an anti-aging benefit of CoQ10 supplementation in human subjects. In a preliminary pilot study, 25 female subjects between 45 and 55 y of age were recruited at Stanford University from the Palo Alto, CA area. Informed consent was obtained. Ten of the subjects received Coenzyme Q10 supplementation of 180 (3 × 60 mg) per day for 28 days. Serum, saliva and perspiration levels of arNOX were determined at 7, 14 and 28 days of CoQ10 supplementation and compared to the initial baseline value. Activity correlated with subject age up to a maximum between age 50 and 55 years of age for saliva and perspiration as well and then declined. With all three sources, the arNOX activity extrapolated to zero at about age 30. Response to Coenzyme Q10 also increased with age being least between ages 45 and 50 and greatest between ages 60 and 65. With all three biofluids, arNOX activity was reduced between 25 and 30% by a 3 × 60 mg daily dose Coenzyme Q10 supplementation. Inhibition was the result of Coenzyme Q10 presence. [source]