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991.
Vega Prez Gracia Jos Antonio Canas Lluis G. Pujades Jaume Claps Oriol Caselles Francesc García Raul Osorio 《Journal of Applied Geophysics》2000,43(2-4)
This paper describes the ground-penetrating radar (GPR) survey performed inside the Cathedral of Valencia, Spain. It is part of historical studies performed in the Cathedral in order to add information to old maps and documents in the Cathedral Archives and also to analyze the extent and importance of potentially destructive moisture areas that were appearing on the floor. The construction of the Cathedral of Valencia occurred in three stages, all of which are well-documented in the Cathedral Archives with detailed drawings, maps, and charts. The radar data were successful in locating crypts, ossuaries, sepulchers, and graves, and the location of ancient walls that existed before the final Cathedral expansion. Three cultural layers corresponding to the three periods of construction were also identified corresponding to the Roman, Arabian and Middle Age Epochs. Measurements of relative sub-floor moisture were obtained by comparing dielectric permittivity changes and radar velocity differences between materials in humid and non-humid areas. 相似文献
992.
Jaime Burgos-García Joaquín Delgado 《Celestial Mechanics and Dynamical Astronomy》2013,117(2):113-136
The restricted three-body problem (R3BP) possesses the property that some classes of doubly asymptotic (i.e., homoclinic or heteroclinic) orbits are limit members of families of periodic orbits, this phenomenon has been known as the “blue sky catastrophe” termination principle. A similar case occurs in the restricted four body problem for the collinear equilibrium point $L_{2}$ L 2 . In the restricted four body problem with primaries in a triangle relative equilibrium, we show that the same phenomenon observed in the R3BP occurs. We prove that there exists a critical value of the mass parameter $\mu _{b}$ μ b such that for $\mu =\mu _{b}$ μ = μ b a Hamiltonian Hopf bifurcation takes place. Moreover we show that for $\mu >\mu _{b}$ μ > μ b the stable and unstable manifolds of $L_{2}$ L 2 intersect transversally and the spectrum corresponds to a complex saddle. This proves that Henrard’s theorem applies at least for $\mu $ μ close to $\mu _{b}$ μ b . In particular there exists a family of periodic orbits having the homoclinic orbit as a limit. 相似文献
993.
LISA Pathfinder is a science and technology demonstrator of the European Space Agency within the framework of its LISA mission,
which aims to be the first space-borne gravitational wave observatory. The payload of LISA Pathfinder is the so-called LISA
Technology Package, which is designed to measure relative accelerations between two test masses in nominal free fall. Its
disturbances are monitored and dealt by the diagnostics subsystem. This subsystem consists of several modules, and one of
these is the magnetic diagnostics system, which includes a set of four tri-axial fluxgate magnetometers, intended to measure
with high precision the magnetic field at the positions of the test masses. However, since the magnetometers are located far
from the positions of the test masses, the magnetic field at their positions must be interpolated. It has been recently shown
that because there are not enough magnetic channels, classical interpolation methods fail to derive reliable measurements
at the positions of the test masses, while neural network interpolation can provide the required measurements at the desired
accuracy. In this paper we expand these studies and we assess the reliability and robustness of the neural network interpolation
scheme for variations of the locations and possible offsets of the magnetometers, as well as for changes in environmental
conditions. We find that neural networks are robust enough to derive accurate measurements of the magnetic field at the positions
of the test masses in most circumstances. 相似文献
994.
F. Soydugan A. Erdem S.S. Doğru F. Aliçavuş E. Soydugan C. Çiçek O. Demircan 《New Astronomy》2011,16(4):253-264
This study presents an investigation of the orbital period variations of five Algol type binaries, UX Leo, RW Mon, EQ Ori, XZ UMa and AX Vul based on all available minima times. The O–C diagrams of all systems exhibit a periodic variation superimposed on a downward parabolic segment. The mass loss due to magnetic braking effect in the cooler components is assumed to account for the parabolic variation with a downward shape, while it is suggested that the light-time effect (LITE) due to an unseen component around the eclipsing binaries explains the tilted sinusoidal changes in their O–C diagrams. The orbital period decrease rates for the systems are estimated as approximately between about 0.7 and 2.5 s per century. It is clearly seen that mass loss effect is more dominant than the expected mass transfer for classical Algols in this study. The minimum mass of the probable third bodies around the eclipsing pairs was calculated to be ?0.5 M⊙ except for UX Leo, in which it was estimated to be approximately 0.9 M⊙. In order to search for third lights in the light curves of five systems, the V-light curves of the systems were analyzed and their physical and photometric parameters were determined. For UX Leo, a significant third light contribution was determined. We found a very small third light that can be tested using multi-color light curves, for RW Mon, EQ Ori and XZ UMa, while a third light for AX Vul could not be exposed. 相似文献
995.
C. Martayan A. Alvarez P. Bristow R. Castillo H. Dekker S. D'Odorico V. Mainieri E. Mason A. Modigliani S. Moehler P. Moller F. Patat E. Pena C. Reinero J. Vernet J. Vinther M. Vuckovic all the engineers who work a lot on X‐shooter 《Astronomische Nachrichten》2011,332(3):222-223
We report on the current performances and measurements done with X‐shooter during its first year of operations at Paranal. We present the current instrumental problems, recent and future improvements, and give advice for the observations (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
996.
The Niger River is one of the most important sources of water supply for human consumption and agriculture in Western Africa. Two Landsat‐5 Multispectral Scanner (MSS) images, corresponding to the dry and wet seasons, over a selected area of the Niger River interior delta were classified to produce a land cover/land use map that reflects the geo‐hydrological units of this area. To classify the satellite data, training statistics were generated using a clustering algorithm with parameter values that maximize the separability among spectral classes. Both dry and wet season images are required to obtain an accurate classification for evaluation of hydrological parameters. The spatial resolution of the MSS proved to be adequate for this kind of work, since all the major cover types and geographic features were correctly recognized. 相似文献
997.
目的和意义:依托医院PACS安装和实施的契机,充分利用医院的病例特点和中医诊疗优势,通过结合中医辨证论治的要求对医学影像和信息进行计算机智能化处理后,达到摒弃影像诊断传统的肉眼观察和主观判断的目的。借助计算机技术,对影像的像素点进行分析、计算和处理,以得到相关的完整数据,为医学影像诊断提供更客观的信息的同时建立相关不同疾病分类的教学模块,填补国内在中医药大学医学影像学教学和科研计算机评价体系方面的空白,为临床、科研和教学工作提供了更可靠的工具。 相似文献
998.
Ana Lorena Esteban‐García Raquel Lebrero Manuel Alejandro de los Santos Raúl Muñoz Juan Ignacio Tejero 《洁净——土壤、空气、水》2013,41(5):469-472
A study was performed in two submerged, pilot‐scale biofilm bioreactors operated under different conditions to determine the relationship between the operating parameters and H2S emission. H2S was always detected in the exhaust air at concentrations varying from 1 to 353 ppmv. The specific aeration rate was the most influencing parameter, with As < 30 kg COD (dissolved oxygen concentrations <4 mg L?1) increasing noticeably the H2S production. The periodical removal of the accumulated sludge reduced H2S emissions by ~14%. 相似文献
999.
Javier Santos-González João A. Santos Rosa Blanca González-Gutiérrez José María Redondo-Vega Amelia Gómez-Villar 《自然地理学》2013,34(6):471-490
Fabric and grain-size analysis of eight deposits present in the Upper Sil River Basin palaeoglacial system of northwest Spain were used to interpret till types and to reconstruct the glacial paleoprocess history of this region. They are represented by lodgement, deformation, and melt-out tills. The first, representative of glacial advance stages, present cluster fabrics and are generally composed of poorly sorted and finer sediments. Melt-out and deformation tills, representative of stages of glacial stability followed by fast recession, present transitional to girdle fabrics and are composed of poorly sorted coarser sediments. In any case, multiple criteria, including lithological, clast-shape, or structural data, support these directional and grain-size observations. These sequences, most of them located in the snout area of the Sil palaeoglacier, are important in the reconstruction of glacial dynamics due to poor preservation of landforms related to the maximum glacial advance. This palaeoglacial system was formed by multiple tributaries and had an extension of over 450 km2, with the Sil paleoglacier being 51 km long during its maximum glacial advance. 相似文献
1000.
Antonio T. Mozas-Calvache Manuel Antonio Ureña-Cámara José Luis Pérez-García 《International journal of geographical information science》2013,27(12):2362-2374
This article describes a new methodology for the planimetric control of contour lines. The method is based on the generation of buffers around the contour lines which define a 3D buffer around the maximum slope line. After that we analyze the quantity of points from a more accurate source which is inside this buffer. As a result, we obtain a distribution function of the control points included when we apply several widths to the buffers. We have also determined the angularity and height differences of these points. The method has been applied to several sets of contour line intervals derived from a digital elevation model (DEM) and to the contour lines of one published topographic map using the DEM as the control source. We have also analyzed the representative behaviour of the contour lines, taking into account the contour line interval and the detection of an uncertainty model based on the slope variation. This study demonstrates the viability of the proposed method for obtaining the uncertainty of the contour lines depending on a given level of confidence and the variability of this uncertainty in the map. Finally, we propose a range of contour line intervals based on the scale and slopes. 相似文献