The radioastronomical “time machine” effect can help the solution of the gamma ray bursts mystery     

Galina V. Lipunova  Ivan E. Panchenko  Vladimir M. Lipunov 《New Astronomy》1997,2(6):555-558

The possible low-frequency radio emission from the progenitors of gamma ray bursts can experience a delay from tens of seconds to hours on the way to the observer due to the dispersion in galactic and extragalactic plasma, and thus reach the observer as a radio afterglow of the burst. This opens a unique possibility (peculiar “time machine”) of seeing what happened at that place before the catastrophe.  相似文献   

FDwave3D: a MATLAB solver for the 3D anisotropic wave equation using the finite-difference method     

Li  Lei  Tan  Jingqiang  Zhang  Dazhou  Malkoti  Ajay  Abakumov  Ivan  Xie  Yujiang 《Computational Geosciences》2021,25(5):1565-1578

Seismic modeling plays an important role in geophysics and seismology for estimating the response of seismic sources in a given medium. In this work, we present a MATLAB-based package, FDwave3D, for synthetic wavefield and seismogram modeling in 3D anisotropic media. The seismic simulation is carried out using the finite-difference method over the staggered grid, and it is applicable to both active and passive surveys. The code package allows the incorporation of arbitrary source mechanisms and offers spatial derivative operators of accuracy up to tenth-order along with different types of boundary conditions. First, the methodological aspects of finite-difference method are briefly introduced. Then, the code has been tested and verified against the analytical solutions obtained for the homogeneous model. Further, the numerical examples of layered and overthrust models are presented to demonstrate its reliability.

  相似文献   

Aligned olivine in the Springwater pallasite          下载免费PDF全文

Neva A. Fowler‐Gerace  Kimberly T. Tait  Desmond E. Moser  Ivan Barker  Bob Y. Tian 《Meteoritics & planetary science》2016,51(6):1125-1135

The mechanism by which olivine grains became embedded within iron‐nickel alloy in pallasite meteorites continues to be a matter of scientific debate. Geochemical and textural observations have failed to fully elucidate the origin and history of the olivine crystals; however, little research attention has been devoted to their crystallographic orientations within the metal matrix. Using electron backscatter diffraction, we have collected crystallographic orientation data for 296 crystals within ～65 cm² sample surface from Springwater. Though no global crystallographic preferred orientation exists, very low misorientations are observed among [100] axes of olivine crystals within specific texturally defined domains. Combined with a thorough characterization of large‐scale Springwater textures, the definitively nonrandom spatial distribution of olivine orientations provides clues regarding the nature of the olivine's initial formation environment as well as the sequence of events subsequent to metal incorporation.  相似文献   

Brittle and ductile deformation in extensional tectonic settings within the Central Asian Orogenic Belt (evidence from Geotransect «East Siberian Plate - Siberian Craton –Central Asian Belt»)     

Ivan V. Kudriavtcev  Oleg V. Petrov  Sergey N. Kashubin  Evgeniia D. Milshtein  Evgeniy Al. Androsov 《《地质学报》英文版》2018,92(Z1):115-116

  相似文献   

Heat wave risk assessment and mapping in urban areas: case study for a midsized Central European city,Novi Sad (Serbia)   总被引：1，自引：0，他引：1  

Stevan Savić  Vladimir Marković  Ivan Šećerov  Dragoslav Pavić  Daniela Arsenović  Dragan Milošević  Dragan Dolinaj  Imre Nagy  Milana Pantelić 《Natural Hazards》2018,91(3):891-911

Risk assessment and mapping methodologies for heat waves as frequently occurring hazards in central and southeastern Europe were applied in this study, and the impact of heat waves on the mortality of urban populations was determined as part of the assessment. The methodology for conducting the heat wave risk assessment is based on European Commission’s Guidelines for Risk Assessment and Mapping. The Novi Sad (Serbia) urban area was studied during summer 2015, which was one of the hottest summers in the last few decades. In situ air temperature measurements from urban stations and mortality of urban populations were used. Nocturnal urban heat island (UHI) intensity values between the various built-up zones and natural surrounding areas were used for the hazard level calculation. Temperature data from 9 p.m. to 5 a.m. were used because during the night, the UHI intensity reached its maximum values. The average daily number of deaths by LCZs was used to define the impact level of the vulnerability index. Calculations for both hazard levels were completed during two intensive heat waves (in July and August 2015) when it was expected that there may be a high level of risk. The results and maps show that the urban area is complex, and the heat wave risk on the population is not uniform. The most densely built-up areas (LCZs 2, 5 and 6) have very high or high risk values that are influenced by a higher rate of mortality. The obtained results and maps can be used by local authorities to prevent and mitigate climate-related hazards, for medical institutions as well as urban planners and for ancillary local, regional or national services. According to these results, the local authorities could define hot spots where they can place medical and rescue teams and install points with water supplies, etc.  相似文献   

Geochemical evolution of tourmaline in the Darasun gold district,Transbaikal region,Russia: evidence from chemical and boron isotopic compositions     

Ivan A. Baksheev  Vsevolod Yu. Prokofiev  Robert B. Trumbull  Michael Wiedenbeck  Vasilii O. Yapaskurt 《Mineralium Deposita》2015,50(1):125-138

  相似文献   

Geochemical signal of seasonality in annually laminated organic- carbonate sediments in Shira lake(Khakasia)     

Ivan KALUGIN  Andrey DARIN  Denis ROGOZIN  Gennady TRET’YAKOV 《《地质学报》英文版》2014,88(Z1):12-13

正1 Introduction The most valuable for the task of climate reconstruction are the time series with an annual resolution,which allows to reveal natural periodicity and pass to the search for mechanisms of regional and global climatic changes.Bottom sediments of lakes are one of the best climate archives in addition to tree ring series,ice cores etc.  相似文献   

A Bayesian vulnerability assessment tool for drinking water mains under extreme events   总被引：2，自引：1，他引：1  

Alessandro Pagano  Raffaele Giordano  Ivan Portoghese  Umberto Fratino  Michele Vurro 《Natural Hazards》2014,74(3):2193-2227

Drinking water security is a life safety issue as an adequate supply of safe water is essential for economic, social and sanitary reasons. Damage to any element of a water system, as well as corruption of resource quality, may have significant effects on the population it serves and on all other dependent resources and activities. As well as an analysis of the reliability of water distribution systems in ordinary conditions, it is also crucial to assess system vulnerability in the event of natural disasters and of malicious or accidental anthropogenic acts. The present work summarizes the initial results of research activities that are underway with the intention of developing a vulnerability assessment methodology for drinking water infrastructures subject to hazardous events. The main aim of the work was therefore to provide decision makers with an effective operational tool which could support them mainly to increase risk awareness and preparedness and, possibly, to ease emergency management. The proposed tool is based on Bayesian Belief Networks (BBN), a probabilistic methodology which has demonstrated outstanding potential to integrate a range of sources of knowledge, a great flexibility and the ability to handle in a mathematically sound way uncertainty due to data scarcity and/or limited knowledge of the system to be managed. The tool was implemented to analyze the vulnerability of two of the most important water supply systems in the Apulia region (southern Italy) which have been damaged in the past by natural hazards. As well as being useful for testing and improving the predictive capabilities of the methodology and for possibly modifying its structure and features, the case studies have also helped to underline its strengths and weaknesses. Particularly, the experiences carried out demonstrated how the use of BBN was consistent with the lack of data reliability, quality and accessibility which are typical of complex infrastructures, such as the water distribution networks. The potential applications and future developments of the proposed tool have been also discussed accordingly.  相似文献   

Detection of detached forced-regressive nearshore wedges: a case study from the central-southern Siena Basin (Northern Apennines, Italy)     

Ivan Martini  Simone Arragoni  Mauro Aldinucci  Luca Maria Foresi  Anna Maria Bambini  Fabio Sandrelli 《International Journal of Earth Sciences》2013,102(5):1467-1489

The detection of detached nearshore wedges formed in response to relative sea-level drops is considered one of the hottest topics in sequence stratigraphic analysis due to their importance as reservoir analogues. In fact, they usually constitute sandy and porous bodies generally encased in impermeable clay, thus presenting a good potential as traps for fluids. This paper focuses on the sequence stratigraphic analysis of the Pliocene deposits cropping out in the central-southern sector of the Siena Basin (Tuscany, Italy), a post-collisional basin of the Northern Apennines. The exposed sedimentary succession was investigated through a detailed sedimentological and stratigraphic approach, integrated by biostratigraphic analyses, aimed at a better characterization of the infilling history of this sector of the basin. Specifically, this study revealed the occurrence of repeated facies shifts that allowed the identification of two depositional sequences. In detail, a thick sand-rich body far from the basin margins, and previously considered as a turbiditic lobe, has been reinterpreted as formed in a nearshore setting during a fall in relative sea level. This body is totally encased in offshore clay, and due to the lack of physical connection with the related HST deposits, it has to be considered as a detached forced-regressive wedge. The present work led to the recognition of some sedimentological and stratigraphic features typical of falling stage systems tract deposits (e.g. presence of intrabasinal recycled materials, sedimentological evidence of a pre-existing fluvial network subsequently eroded) that can provide useful clues for the identification of detached forced-regressive nearshore wedges in core studies and poorly exposed settings.  相似文献   

Increased soil gas radon and indoor radon concentrations in Neoproterozoic olistostromes of the Teplá-Barrandian unit (Czech Republic)     

Ivan Barnet  Petra Pacherová 《Environmental Earth Sciences》2013,69(5):1601-1607

The Neoproterozoic olistostromes were first distinguished as a special geological unit in a generalised geological map of the Czech Republic on a scale 1:500,000. The olistostromes represent a tectonic mélange or subaquatic continental slope-slides formed by a mixture of black shales, greywackes, carbonates and shales, forming an extremely inhomogeneous geological environment. The extreme over-limit values of indoor radon (Rn, ²²²Rn) were first detected during check measurements performed for final building approval by team of the National Radiation Protection Institute in a house situated on bedrock of black shales—lithological component of olistostromes north-eastward from Plzeň. Additional measurements of soil gas Rn performed by the Czech Geological Survey were oriented to cover the whole olistostrome belt extending over 65 × 25 km area NE of Plzeň–Prague general direction. The increased concentrations both of soil gas and indoor Rn were confirmed in the whole extent of Neoproterozoic olistostrome belt compared to neighbouring geological units (Neoproterozoic metasediments on NW and Cambrian Palaeovolcanites and Ordovician sediments on SE). This observation lead to increasing the radon index of olistostromes to medium radon category (from the low one) both in general and detailed Rn index maps. Drawing the attention to this lithological type enables to improve the radon risk prevention for newly built houses and interest of remediation of existing houses not only in the specific area of the Czech Republic, but also in other European countries, where Neoproterozoic olistostromes form the geological basement.  相似文献