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S. B. Dharmadhikari E. Garcia S. Espinoza J. Dominguez J. M. Goris 《Ocean Engineering》1978,5(3):165-180
This paper describes the process of launching and joining of two sections of a product carrier of 30,500 DWT built at Dianca shipyard at Puerto Cabello, Venezuela. The specifications and characteristics of this ship are in line with the market requirements. This paper deals with the problems encountered during the decision of dividing the ship in two halves, use of syncrolift for launching and subsequent joining of two halves in the dry dock. 相似文献
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JosMaria Landim Dominguez Abilio Carlos da Silva Pinto Bittencourt Louis Martin 《Sedimentary Geology》1992,80(3-4):213-232
East-northeastern Brazil has a wave-dominated, micro- to meso-tidal coast, lying entirely within the southern Atlantic trade wind belt. Integration of geologic mapping, radiocarbon dating and vibracoring data shows that the Quaternary coastal evolution of this area was controlled by three major factors: (1) sea-level history; (2) trade winds; and (3) climate change.
Sea-level history. Along the east-northeastern coast of Brazil, relative sea level has fallen approximately 5 m during the last 5000 y. Correlation of this sea-level history with the evolution of beach-ridge, lagoonal and coastal plain deposits shows that: (1) sea-level rise favours the formation of barrier island—lagoonal systems and the construction of intralagoonal deltas; (2) sea-level lowering is not conductive to barrier island formation. Rather, lagoons and bays become emergent and beach-ridge plains rapidly prograde.
Trade winds. Sediment dispersal systems along the coastal zone of east-northeastern Brazil have been highly persistent since Pleistocene time, as deduced from beach-ridge orientation. This persistence results from the fact that sediment dispersal in wave-dominated settings is ultimately controlled by atmospheric circulation which, for the east-northeastern coast of Brazil is associated with the South Atlantic high-pressure cell. The remarkable stability of this cell through time, has allowed the accumulation of extensive beach-ridge plains at the longshore drift sinks located along the coast.
Climate change. Effects of Quaternary climate changes on coastal sedimentation are twofold. Climate changes may affect rainfall patterns, thus exerting an important control on coastal dune development. Along the coast of northeastern Brazil, active coastal dunes are only present in those areas in which at least four consecutive dry months occur during the year. Mapping of these areas has shown that dune development during the Holocene has been episodic, these episodes being probably controlled by variations in rainfall patterns associated with climate changes. Secondly, despite its overall stability, the position of the high-pressure cell has experienced small shifts in position during the Holocene in response to climate changes. Changes in wind direction associated with these shifts have induced modifications in the coastal dispersion system, which are recorded in the strandplains as small truncations in the beach-ridge alignments.
These results have important implications in understanding accumulation of ancient sandstone shoreline sequences. 相似文献
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Alo Schlagenhauf Isabelle Manighetti Jacques Malavieille Stphane Dominguez 《Earth and Planetary Science Letters》2008,273(3-4):299-311
We conducted a laser-equipped analog experiment aimed at quasi-continuously monitoring the growth of a dense population of normal faults in homogeneous conditions. To further understand the way geological faults progressively gain in slip and length as they accumulate more strain, we measured with great precision the incremental slip and length changes that the analog faults sustain as they grow. These measurements show that the analog faults share common features with the natural ones. In particular, during their growth, the faults develop and maintain cumulative slip profiles that are generally triangular and asymmetric. The growth takes place through two distinct phases: an initial, short period of rapid lateral lengthening, followed by a longer phase of slip accumulation with little or no lengthening. The incremental slip is found to be highly variable in both space (along the faults) and time, resulting in variable slip rates. In particular, ‘short- and long-term’ slip rates are markedly different. We also find that slip measurements at local points on fault traces do not contain clear information on the slip increment repeat mode. Finally, while the fault growth process is highly heterogeneous when considered at the scale of a few slip events, it appears homogeneous and self-similar at longer time scales which integrate many slip increments. This is likely to be the result of a feedback between stress heterogeneities and slip development. The long-term scale homogeneity also implies that the long-term faulting process is primarily insensitive to the short-term heterogeneities that are rapidly smoothed or redistributed. We propose a new conceptual scenario of fault growth that integrates the above observations and we suggest that faults grow in a bimodal way as a result of a self-driven and self-sustaining process. 相似文献
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Julien Charreau Amandine Sartgou Dimitri Saint‐Carlier Jrme Lav Pierre‐Henri Blard Stphane Dominguez Sheng Li Wang Gang Rao 《地学学报》2020,32(1):89-96
In this study, we reconstruct the Miocene to Quaternary shortening history across the Qiulitag anticline, a complex fault‐bend fold located in southern Tianshan. We studied the Yaha and Kuche sections, where we combined surface structural measurements and seismic imaging to model the stratigraphic horizons. The history of folding was reconstructed based on magnetostratigraphic analyses and eight cosmogenic burial ages in Kuche. Pleistocene deformation rates were also quantified in Yaha based on a deformed fluvial terrace that we dated to ~67 ka using a cosmogenic depth profile. Our results suggest that the fold grew at a mean slip rate of 0.9–1.3 mm/a in both sections but accelerated to ~2.5 mm/a during the Pleistocene in Kuche. These results support a migration of the deformation towards the basin during the Pleistocene and suggest that most of the present deformation in the Tianshan is accommodated across the external structures of the range. 相似文献
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Sedimentary kaolin deposits in the Lote 18 area (Santa Cruz Province, Patagonia, Argentina) have been mined since 1951. They constitute 30% of the country's production and are mainly used in the ceramic whiteware industry. The deposits belong to the Baqueró Formation (Lower Cretaceous) and unconfomably overlie either the ash-flow tuffs of the Chon-Aike Formation (Middle Jurassic), which are altered to kaolinite and minor illite, or the ash-fall tuffs of Bajo Grande Formation (Upper Jurassic-Lower Cretaceous), which are altered mainly to smectites. The presence of illite or smectite, as well as the kaolinite crystallinity, depends on the stratigraphic position of the kaolin horizons within the Lower Member of the Baqueró Formation and on the lithology of the underlying rocks. Kaolin beds composed of well-crystallized kaolinite at the base of the sequence overlaying Chon-Aike rocks are the purest. Kaolinite becomes less well cystallized with transport. Edge-to-face and swirl SEM textural patterns indicate the compaction of flocculated clays and clay movement during drainage and compaction. Mineralogical, petrological, and physico-structural evidence (i.e., form, extent, thickness) indicates that the kaolin deposits are sedimentary, formed by the transportation and deposition of previously formed kaolinite. Kaolin beds are ovoidal in plan and lenticular in profile, with thickness ranging from centimeters to 11 meters, and the culmination of fining-upward clastic sequences. Sedimentary facies analysis indicates that the kaolin deposits were formed in a fluvial environment from currents with a high suspended-load/bed-load ratio, as would result from deposition in ox-bow lakes. 相似文献
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Gerardo Dominguez 《Meteoritics & planetary science》2009,44(10):1431-1443
Abstract— Aerogel collectors have been used to capture cometary, interplanetary, and interstellar dust grains by NASA's Stardust mission, highlighting their importance as a scientific instrument. Due to the fragile and heterogeneous nature of cometary dust grains, their fragments are found along the walls of tracks that are formed during the capture process. These fragments appear to experience a wide range of thermal alteration and the causes of this variation are not well understood at a theoretical level as physical models of track formation are not well developed. Here, a general model of track formation that allows for the existence of partially and completely vaporized aerogel material in tracks is developed. It is shown that under certain conditions, this general track model reduces to the kinetic “snowplow” model that has previously been proposed. It is also shown, based on energetic considerations, that track formation is dominated by an expansion that is snowplow‐like in the later stages of track formation. The equation of motion for this snowplow‐like stage can be solved analytically, thus placing constraints on the amount of heating experienced by cometary dust fragments embedded in track walls. It is found that the heating of these fragments, for a given impact velocity, is expected to be greater for those embedded in larger tracks. Given the expected future use of aerogels for sample return missions, the results presented here imply that the choice of aerogel compositions can have a significant effect on the modification of samples captured and retrieved by these collectors. 相似文献
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Juan Argüelles Ricardo Tafur Anatolio Taipe Piero Villegas Friedeman Keyl Noel Dominguez Martín Salazar 《Progress in Oceanography》2008,79(2-4):308
Changes in population structure of the jumbo flying squid Dosidicus gigas in Peruvian waters were studied based on size-at-maturity from 1989 to 2004. From 1989 to 1999, mature squid belonging to the medium-sized group prevailed, but from 2001 on, mature squids were larger. This change is not related to the changes in sea surface temperature and we hypothesized that it was caused by the population increase of mesopelagic fishes as prey. 相似文献
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The boundary element method is used to obtain dynamic stiffness functions of rigid cylindrical foundations embedded in a uniform or layered viscoelastic half-space. Dynamic stiffness functions of hemispherical foundations embedded in a uniform half-space are also computed. The direct integral equation formulation is used in combination with the complete space point load fundamental solution that is integrated numerically along the azimuthal coordinate. The approach is easy to implement because of the simplicity of the fundamental solution. The numerical results obtained by this method for cylindrical and hemispherical foundations are very close to corresponding published results obtained by different procedures. A parametric study shows the important effects of the Poisson's ratio on the dynamic stiffness functions of cylindrical foundations embedded in a uniform viscoelastic half-space. The effect of the bedrock compliance on the stiffness functions is also shown in the case of cylindrical foundations embedded in a soil layer that rests on a bedrock. 相似文献