A new damage model based on non‐local displacements     

Antonio Rodríguez‐Ferran  Irene Morata  Antonio Huerta 《国际地质力学数值与分析法杂志》2005,29(5):473-493

A new non‐local damage model is presented. Non‐locality (of integral or gradient type) is incorporated into the model by means of non‐local displacements. This contrasts with existing damage models, where a non‐local strain or strain‐related state variable is used. The new model is very attractive from a computational viewpoint, especially regarding the computation of the consistent tangent matrix needed to achieve quadratic convergence in Newton iterations. At the same time, its physical response is very similar to that of the standard models, including its regularization capabilities. All these aspects are discussed in detail and illustrated by means of numerical examples. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Chemical abundances determined from meteor spectra – II. Evidence for enlarged sodium abundances in meteoroids     

Josep M. Trigo-Rodríguez  Jordi Llorca  Juan Fabregat 《Monthly notices of the Royal Astronomical Society》2004,348(3):802-810

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The pre-main-sequence star HD 34282: a very short-period δ Scuti-type pulsator     

P. J. Amado  A. Moya  J. C. Suárez  S. Martín-Ruiz  R. Garrido  E. Rodríguez  C. Catala  M. J. Goupil 《Monthly notices of the Royal Astronomical Society》2004,352(2):L11-L15

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A study of the behaviour of the Na i/K i column density ratio in the interstellar medium using the Na ultraviolet doublet     

S. N. Kemp  B. Bates  J. E. Beckman  C. J. Killow  R. Barrena  D. C. Kennedy  J. Rodríguez Alamo 《Monthly notices of the Royal Astronomical Society》2002,333(3):561-574

Here we make a new study of the behaviour of the Na  i /K  i column density ratio in the interstellar medium, using a sample of new observations of 28 stars obtained at the Nordic Optical Telescope (NOT) in 1996 and 1997, and previously published observations (obtained by some of the authors) of 21 stars. The sightlines cover a range of distances and directions, including into the Galactic halo. We make use of new observations of the Na  i ultraviolet (UV) doublet for some 18 stars. This doublet is much weaker than the Na  i D doublet and so is less susceptible to saturation effects, and it is well known that it can be used to obtain more accurate Na  i column densities with a smaller error range. We find an average N (Na  i )/ N (K  i ) ratio from the Na  i UV data of about 90, which is rather higher than that found previously by Hobbs and Lequeux. The Na  UV–K  i   ratio shows a small increase in value with increasing column density, while we also find a sample of low N (Na  i )/ N (K  i ) ratio clouds generally seen towards distant objects on high-latitude sightlines that reach into the halo, so that the ratio decreases more sharply at lower column densities. As the values of the ratio for these halo clouds  (10–20)  bracket the cosmic Na/K abundance ratio, we suggest that these ratios result from a harder radiation field in the lower halo, such that the ionized fractions of Na  i and K  i become similar. Clearly caution needs to be applied in using any kind of 'standard value' for the Na  i /K  i column density ratio.  相似文献   

Long-Term Amateur Ccd Monitoring Of Comet C/1999 S4 (Linear)     

Rodríguez  Juan  Sánchez  Salvador  García  Antonio  Blasco  Manolo  Villalonga  Miquel A. 《Earth, Moon, and Planets》2002,90(1-4):185-194

The results from the analysis of the extensive CCD photometry that we haveobtained during the long-term monitoring (from its discovery until its break-up)of comet C/1999 S4 (linear) are presented here. Our observations showthat the comet did not always behave as expected: it showed activity ahead oftime and in the end became fainter instead of brighter as it approached perihelion.A sequence of images and a lightcurve are shown.  相似文献   

Asteroseismology of the β Cephei star ν Eridani – IV. The 2003–2004 multisite photometric campaign and the combined 2002–2004 data     

M. Jerzykiewicz  G. Handler  R. R. Shobbrook †  A. Pigulski  R. Medupe  T. Mokgwetsi  P. Tlhagwane  E. Rodríguez 《Monthly notices of the Royal Astronomical Society》2005,360(2):619-630

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VLA observations at 7 mm of the planetary nebula IC 4997     

Y. Gómez  L. F. Miranda  J. M. Torrelles  L. F. Rodríguez  J. A. López 《Monthly notices of the Royal Astronomical Society》2002,336(4):1139-1142

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Modelling arsenic hazard in Cambodia: A geostatistical approach using ancillary data     

Luis Rodríguez Lado  David Polya  Lenny Winkel  Michael Berg  Aimee Hegan 《Applied Geochemistry》2008

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Chemical and geological control of spring water in Eastern Guaniguanico mountain range, Pinar del Rìo, Cuba     

Juan Reynerio Fagundo-Castillo  Joel José Carrillo-Rivera  Iñaki Antigüedad-Auzmendi  Patricia González-Hernández  Roberto Peláez-Díaz  Rebeca Hernández-Díaz  Dámaso Cáceres-Govea  José Ramón Hernández-Santana  Margaret Suárez-Muñoz  Clara Melián-Rodríguez  Mónica Rodríguez-Piña 《Environmental Geology》2008,55(2):247-267

Flows of different hierarchy, which travel through limestone, schist, sandstone and ultra-basic rocks, with ages from the Paleocene to the Jurassic, at Sierra del Rosario, Pinar del Río, Cuba, were characterized. The waters were sampled from 1984 until 2004 and the data were statistically processed by means of chemical equilibrium and physico-chemical models, under a flow system view of interpretation. Results demonstrate that the physico-chemical properties of the water are controlled by water–rock interaction resulting from residence time since rainwater infiltrate and the path it follows to the discharge zone and the type of aquifer material the different groundwater flows are in contact with. Geochemical indices allow the definition of the different types of flow (local, intermediate, regional) to be characterized, permitting a further definition of the different flow systems and rock type involved, as well as its use for water supply and medical use. The main geochemical processes which control the chemical composition acquisitions mode are: congruent dissolution of calcite, dolomite, and halite; incongruent dissolution of plagioclase and microcline minerals; pyrite oxidation, sulphate reduction, and silica dissolution at the surface or silica precipitation at deep saturation and circulation zones.  相似文献   

A combined single range and single image device for low-cost measurement of building façade features     

Celestino  Ordóñez  Pedro  Arias  José  Herráez  Jaime  Rodríguez  María T.  Martín 《The Photogrammetric Record》2008,23(122):228-240

The dimensions of building façades and window apertures are usually determined by making direct measurements using tapes and plummets. This approach, however, has a number of drawbacks including the physical risk to which the persons making the measurements are exposed. This paper proposes an indirect approach based on close range photogrammetry that is inexpensive, simple, fast and safe, and which does not require specialist staff or direct ground control measurements. The method is based on taking a picture using a digital camera and measuring the distance to the object using a handheld laser distance meter. Both items of equipment are mounted on a specially designed support that allows the laser distance meter to move independently of the camera.  相似文献