A mitochondrial DNA PCR-RFLP marker for population studies of the black scabbardfish (Aphanopus carbo)     

Quinta  Ricardo; Gomes  Laurentina; Teia dos Santos  Ana 《ICES Journal of Marine Science》2004,61(5):864-867

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Analysis of roll motion and stability of a fishing vessel in head seas   总被引：1，自引：0，他引：1  

M. A. Santos Neves  N. Prez  O. Lorca 《Ocean Engineering》2003,30(7):921-935

The present paper describes an investigation on the relevance of parametric resonance for a typical fishing vessel in head seas. Results for different Froude numbers are discussed based on experimental, numerical and analytical studies.The first region of resonance is investigated. Distinct wave amplitudes are considered. Some intense resonances are found to occur. The paper compares the experimental results with non-linear time simulations of the roll motion. Very good agreement is found, even when large motions take place.Finally, in order to analyze the experimental/numerical results, analytic consideration is given to distinct parameters affecting the dynamic process of roll amplification. The influence of heave, pitch, wave passage effect, speed and roll restoring characteristics are discussed.  相似文献   

Possible patterns in the distribution of planetary formation regions     

J. L. Ortiz  F. Moreno  A. Molina  P. Santos Sanz  P. J. Gutiérrez 《Monthly notices of the Royal Astronomical Society》2007,379(3):1222-1226

Eris, an object larger than Pluto, is known to reside in the transneptunian region further away than Pluto. One can wonder whether its semimajor orbital axis fits in a generalized Titius–Bode law, in the same way as Pluto does. We performed a new least-squares fit to a generalized Titius–Bode law including Eris and found that not only does Eris fit in the trend, but also the correlation coefficient improves. In addition, there is a remarkable symmetry of the location of the planetary formation regions with respect to Jupiter when the natural logarithm of the heliocentric distance is used as the metric. The issue of whether the observed patterns have some physical meaning or are due to mere chance is addressed using a Monte Carlo approach identical to that of Lynch. Although the probability of chance occurrence is highly dependent on the way in which the random configurations of synthetic planetary systems are selected, we find that in all reasonable scenarios of random planetary systems the probability of chance occurrence of the observed patterns is small (below 1 per cent in most cases). If the trend were used as a prediction tool, one might expect another planet or dwarf planet or a swarm of bodies with semimajor orbital axis of 120 ± 20 au. Simple calculations show that the protoplanetary nebula most likely had enough mass to allow the accretion of at least a dwarf planet at that distance. We also found that if the surface density of the nebula decayed with heliocentric distance ( r ) as a power of −2, the regular spacing in ln  r in the Solar system could be a natural consequence of the existence of a threshold mass for planetary formation.  相似文献   

Modelling discharge through artesian springs based on a high‐resolution piezometric network          下载免费PDF全文

P. Martínez‐Santos  S. Díaz‐Alcaide  S. Castaño‐Castaño  A. Hernández‐Espriú 《水文研究》2014,28(4):2251-2261

Artesian springs are localized aquifer outlets that originate when pressurized ground water is allowed to rise to the surface. Computing artesian discharge directly is often subject to practical difficulties such as restricted accessibility, abundant vegetation or slow flow rates. These circumstances call for indirect approaches to quantify flow. This paper presents a method to estimate ground water discharge through an upwelling spring by means of a three‐layer steady‐state groundwater flow model. Model inputs include on‐site measurements of vertical sediment permeability, sediment temperatures and hydraulic gradients. About 70 spring bed piezometers were used to carry out permeability tests within the spring sediments, as well as to quantify the hydraulic head at different depths below the discharge point. Sediment temperatures were measured at different depths and correlated to permeabilities in order to demonstrate the potential of temperature as a substitute for cumbersome slug tests. Results show that the spatial distribution of discharge through the spring bottom is highly heterogeneous, as sediment permeability varies by several orders of magnitude within centimetres. Sensitivity analyses imply that geostatistical interpolation is irrelevant to the results if field datasets come from a sufficiently high resolution of piezometric records. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Settlement Analysis of Açu Dam,Brazil     

de Souza  Andriele Nascimento  da Silva  Aline Ribeiro  Santos  Olavo F.  de Freitas Neto  Osvaldo 《Geotechnical and Geological Engineering》2022,40(3):1565-1583

Geotechnical and Geological Engineering - The Armando Ribeiro Gonçalves Dam, popularly known as The Açu Dam, is an important geotechnical construction in Rio Grande do Norte state,...  相似文献   

Suitability of GNSS for analysis of soil subsidence in Recife in a highly urbanized coastal area     

de Luna  Rejane Maria Rodrigues  dos Anjos Garnés  Silvio Jacks  da Silva Pereira Cabral  Jaime Joaquim  dos Santos  Sylvana Melo 《Natural Hazards》2021,106(3):1821-1837

Natural Hazards - Recife Metropolitan Region, in the northeast of Brazil, is formed by a coastal plain bounded by hills and by the Atlantic Ocean. Recife Metropolitan Region has about 4 million...  相似文献   

Land use and land cover dynamics in Leiria City: relation between peri-urbanization processes and hydro-geomorphologic disasters     

Barros  José Leandro  Tavares  Alexandre Oliveira  Santos  Pedro Pinto 《Natural Hazards》2021,106(1):757-784

Natural Hazards - The objective of the present study is to evaluate the relation between the spatial and temporal dynamics of Land Use and Land Cover (LULC) and the hydro-geomorphological processes...  相似文献   

Reply to Discussion “Geopolymers Based on Recycled Glass Powder for Soil Stabilization” Jair de Jesús Arrieta Baldovino,Ronaldo Luis dos Santos Izzo,Juliana Lundgren Rose,and Mônica Angélica Avanci     

de Jesús Arrieta Baldovino  Jair  dos Santos Izzo  Ronaldo Luis  Rose  Juliana Lundgren  Avanci  Mônica Angélica 《Geotechnical and Geological Engineering》2021,39(6):4655-4657

Geotechnical and Geological Engineering -  相似文献   

Core Jamming in Unconsolidated Formations     

Peixoto Filho  Flávio Tito  Vargas Junior  Euripedes do Amaral  Santos  Erick Slis Raggio  Ferreira  Francisco Henriques 《Geotechnical and Geological Engineering》2021,39(6):4127-4142

Geotechnical and Geological Engineering - In coring operations, core jamming is a permanent concern, taking place when the rock core sample becomes stuck within the inner core barrel, thus...  相似文献   

Ray-traced slant factors for mitigating the tropospheric delay at the observation level   总被引：3，自引：2，他引：1  

Landon?UrquhartEmail author  Felipe?G.?Nievinski  Marcelo?C.?Santos 《Journal of Geodesy》2012,86(2):149-160

Three-dimensional ray tracing through a numerical weather model has been applied to a global precise point positioning (PPP) campaign for modeling both the elevation angle- and azimuth-dependence of the tropospheric delay. Rather than applying the ray-traced slant delays directly, the delay has been parameterized in terms of slant factors, which are applied in a similar manner to traditional mapping functions, but which can account for the azimuthal asymmetry of the delay. Five strategies are considered: (1) Vienna Mapping Functions 1 (VMF1) and estimation of a residual zenith delay parameter; (2) VMF1, estimation of a residual zenith delay and estimation of two tropospheric gradient parameters; (3) three-dimensional ray-traced slant factors and estimation of a residual zenith delay; (4) using only ray-traced slant factors and no estimation of any tropospheric parameters and; (5) using both ray-traced slant factors and estimating a residual zenith delay and two tropospheric gradient parameters. The use of the ray-traced slant factors (solution 3) showed a 3.8% improvement in the repeatability of the up component when compared to the assumption of a symmetric atmosphere (solution 1), while the estimation of two tropospheric gradient parameters gave the best results showing an 7.6% improvement over solution 1 in the up component. Solution 4 performed well in the horizontal domain, allowing for sub-centimeter repeatability but the up component was degraded due to deficiencies in the modeling of the zenith delay, particularly for stations located at equatorial latitudes. The magnitude of the differences in the mean coordinates between solution 2 and solution 3, and the strong correlation with the differences between the north component and the ray-traced gradients (coefficient of correlation of 0.83), as well as the impact of observation geometry on the gradient solution indicate that the use of the ray-traced slant factors could have an implication on the realization of reference frames. The estimated tropospheric products from the PPP solutions were compared to those derived from ray tracing. For the zenith delay, a root mean square (RMS) of 5.4 mm was found, while for the gradient terms, a correlation coefficient of 0.46 for the N–S and 0.42 for the E–W was found for the north–south and east–west components, suggesting that there are still important differences in the gradient parameters which could be due to either errors in the NWM or to non-tropospheric error sources leaking into the PPP-estimated gradients.  相似文献