Some foundation stability problems of the railway bridge over the Mala Rijeka     

Ž. Radosavljević  O. Marković 《Rock Mechanics and Rock Engineering》1977,9(1):55-64

SummarySome Foundation Stability Problems of the Railway Bridge over the Mala Rijeka The authors presented an outlay of problems occurring in estimating the stability of rocky slopes loaded by large vertical forces. General attitudes, kept by the authors during the stability analysis for an actual case — foundation of piers No. 3 and 4 of the railway bridge across the Mala Rijeka, are also presented. The results of calculation as well as the advantages of the approach applied are outlined in the paper. Finally, general conclusions are drawn regarding the method to be kept in solving the stability of slopes loaded by large artificial loading.With 7 Figures  相似文献   

New Definition of Discovery for Solar System Objects     

Andrea Milani  Giovanni F. Gronchi  Zoran Knežević 《Earth, Moon, and Planets》2007,100(1-2):83-116

We propose a new formal definition of discovery for a Solar System object. It is based on an objective and mathematically rigorous algorithm to assess when a set of observations is enough to constitute a discovery. When this definition is satisfied, in almost all cases the orbit is defined well enough to establish the nature of the object discovered (Main Belt vs. Near Earth Asteroid, Trans-Neptunian vs. long period comet). The frequency of occurrence of exceptions is estimated by a set of numerical experiments. The availability of a non-subjective definition of discovery allows some rules to be adopted for the assignment of discovery credit with a minimum risk of dispute. Such rules should be fair, encourage good practice by the observers and acknowledge the contribution of the orbit computers providing the identifications and the orbits, as well as the one of all the contributing observers.  相似文献   

Footwall mineralization during Late Miocene extension along the West Cycladic Detachment System,Lavrion, Greece     

Alexandra Berger  David A. Schneider  Bernhard Grasemann  Daniel Stockli 《地学学报》2013,25(3):181-191

The West Cycladic Detachment System (WCDS) has been mapped from the western Cycladic islands to Lavrion (mainland Greece), where several top‐to‐SSW low‐angle normal faults at different structural levels are observed. Near the detachment horizon, hydrothermal fluid flow originating from Miocene intrusions lead to high‐temperature carbonate strata‐bound Pb–Ag–Zn ore deposits. Zircon (U–Th)/He cooling ages from the mineralized footwall are 7.1 ± 0.6 to 7.9 ± 0.6 Ma. Carbon‐ and O‐isotope analyses of the carbonate host indicate high water‐to‐rock ratios during brittle deformation‐induced metasomatism, and that this interaction, unrelated to proximity of the intrusions, plays the dominant role in the mineralization. The Late Miocene geology of Lavrion is strikingly similar to Serifos island on the SE termination of the WCDS, both characterized by strong localization of detachment faulting and the interaction of brittle deformation with the injection of fluids related to granitoid intrusions.  相似文献   

Radionuclides and mercury in the salt lakes of the Crimea     

Natalya Mirzoyeva  Larisa Gulina  Sergey Gulin  Olga Plotitsina  Alexandra Stetsuk  Svetlana Arkhipova  Nina Korkishko  Oleg Eremin 《中国海洋湖沼学报》2015,33(6):1413-1425

90 Sr concentrations,resulting from the Chernobyl NPP accident,were determined in the salt lakes of the Crimea(Lakes Kiyatskoe,Kirleutskoe,Kizil-Yar,Bakalskoe and Donuzlav),together with the redistribution between the components of the ecosystems.The content of mercury in the waters of the studied reservoirs was also established.Vertical distributions of natural radionuclide activities( 238 U,232 Th,226 Ra,210 Pb,40 K) and anthropogenic 137 Cs concentrations(as radiotracers) were determined in the bottom sediments of the Koyashskoe salt lake(located in the south-eastern Crimea) to evaluate the longterm dynamics and biogeochemical processes.Radiochemical and chemical analysis was undertaken and radiotracer and statistical methods were applied to the analytical data.The highest concentrations of 90 Sr in the water of Lake Kiyatskoe(350.5 and 98.0 Bq/m 3) and Lake Kirleutskoe(121.3 Bq/m 3) were due to the discharge of the Dnieper water from the North-Crimean Canal.The high content of mercury in Lake Kiyatskoe(363.2 ng/L) and in seawater near Lake Kizil-Yar(364 ng/L) exceeded the maximum permissible concentration(3.5 times the maximum).Natural radionuclides provide the main contribution to the total radioactivity(artificial and natural combined) in the bottom sediments of Lake Koyashskoe.The significant concentration of 210 Pb in the upper layer of bottom sediments of the lake indicates an active inflow of its parent radionuclide—gaseous 222 Rn from the lower layers of the bottom sediment.The average sedimentation rates in Lake Koyashskoe,determined using 210 Pb and 137 Cs data,were 0.117 and 0.109 cm per year,respectively.  相似文献   

Virilization of the Broad Line Region in Active Galactic Nuclei—connection between shifts and widths of broad emission lines     

S. Jonić  J. Kovačević-Dojčinović  D. Ilić  L. Č. Popović 《Astrophysics and Space Science》2016,361(3):101

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Hyperspectral mapping of alteration assemblages within a hydrothermal vug at the Haughton impact structure,Canada          下载免费PDF全文

Rebecca N. Greenberger  John F. Mustard  Gordon R. Osinski  Livio L. Tornabene  Alexandra J. Pontefract  Cassandra L. Marion  Roberta L. Flemming  Janette H. Wilson  Edward A. Cloutis 《Meteoritics & planetary science》2016,51(12):2274-2292

Meteorite impacts on Earth and Mars can generate hydrothermal systems that alter the primary mineralogies of rocks and provide suitable environments for microbial colonization. We investigate a calcite–marcasite‐bearing vug at the ~23 km diameter Haughton impact structure, Devon Island, Nunavut, Canada, using imaging spectroscopy of the outcrop in the field (0.65–1.1 μm) and samples in the laboratory (0.4–2.5 μm), point spectroscopy (0.35–2.5 μm), major element chemistry, and X‐ray diffraction analyses. The mineral assemblages mapped at the outcrop include marcasite; marcasite with minor gypsum and jarosite; fibroferrite and copiapite with minor gypsum and melanterite; gypsum, Fe³⁺ oxides, and jarosite; and calcite, gypsum, clay, microcline, and quartz. Hyperspectral mapping of alteration phases shows spatial patterns that illuminate changes in alteration conditions and formation of specific mineral phases. Marcasite formed from the postimpact hydrothermal system under reducing conditions, while subsequent weathering oxidized the marcasite at low temperatures and water/rock ratios. The acidic fluids resulting from the oxidation collected on flat‐lying portions of the outcrop, precipitating fibroferrite + copiapite. That assemblage then likely dissolved, and the changing chemistry and pH resulting from interaction with the calcite‐rich host rock formed gypsum‐bearing red coatings. These results have implications for understanding water–rock interactions and habitabilities at this site and on Mars.  相似文献   

Seasonal analysis of cold and heat waves in Serbia during the period 1949–2012     

Miroslava Unkašević  Ivana Tošić 《Theoretical and Applied Climatology》2015,120(1-2):29-40

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Dynamical portrait of the Lixiaohua asteroid family     

B. Novaković  K. Tsiganis  Z. Knežević 《Celestial Mechanics and Dynamical Astronomy》2010,107(1-2):35-49

In this paper we present a comprehensive analysis of the dynamics in the region of the (3556) Lixiaohua asteroid family. The family lies in a particularly interesting region of the phase space, crossed by several two-body and three-body mean motion resonances. Also, members of this family can have close encounters with large asteroids, such as Ceres. We have identified the mean motion resonances which contribute to the long-term dynamical evolution of the family and our results confirm that the members of this family can be classified into a number of groups, exhibiting different dynamical behavior. We show for the first time that in the Lixiaohua region, apart from the chaotic diffusion in proper eccentricity and inclination (e _p and I _p ), there is at least one extended chaotic zone where several resonances overlap, thus giving rise to chaotic diffusion in proper semi-major axis (a _p ) as well. Using a code of Monte Carlo type, we simulate the evolution of the family, according to the model which combines the chaotic diffusion (in a _p , e _p and I _p ), Yarkovsky/YORP thermal effect and random walk in a _p due to the close encounters with massive asteroids. These simulations show that all these effects should be taken into account in order to accurately explain the observed distribution of family members in the space of proper elements, although a “minimal” model that accounts for chaotic diffusion in (e _p , I _p ), Yarkovsky-induced drift in a _p and random walk in a _p due to the close encounters with the most massive asteroids is enough to grossly characterize the shape of the family.  相似文献   

A new orbit of binary 15 Monocerotis     

Z. Cvetković  I. Vince  S. Ninković 《New Astronomy》2010,15(3):302-306

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Temporal Evolution of a Rapidly-Moving Umbral Dot     

Hiroko Watanabe  Alexandra Tritschler  Reizaburo Kitai  Kiyoshi Ichimoto 《Solar physics》2010,266(1):5-16

We performed two-dimensional spectroscopic observations of the preceding sunspot of NOAA 10905 located off disk center (S8 E36, μ≈0.81) by using the Interferometric BI-dimensional Spectrometer (IBIS) operated at the Dunn Solar Telescope (DST) of the National Solar Observatory, New Mexico. The magnetically insensitive Fe I line at 709.04 nm was scanned in wavelength repetitively at an interval of 37 s to calculate sequences of maps of the line-wing and line-core intensity, and the line-of-sight Doppler velocity at different line depths (3% to 80%). Visual inspection of movies based on speckle reconstructions computed from simultaneous broadband data and the local continuum intensity at 709.04 nm revealed an umbral dot (UD) intruding rapidly from the umbral boundary to the center of the umbra. The apparent motion of this object was particularly fast (1.3 km s⁻¹) when compared to typical UDs. The lifetime and size of the UD was 8.7 min and 240 km, respectively. The rapid UD was visible even in the line-core intensity map of Fe I 709.04 nm and was accompanied by a persistent blueshift of about 0.06 km s⁻¹.  相似文献