共查询到20条相似文献，搜索用时 31 毫秒
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Øyvind Breivik Jose Henrique Alves Diana Greenslade Kevin Horsburgh Val Swail 《Ocean Dynamics》2017,67(3-4):551-556
Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice. 相似文献
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为了总结在阿尔及利亚地震救援工作中存在的问题和经验教训，联合国人道主义事务办公室于2003年9月9～10日在瑞士日内瓦举行了“阿尔及利亚地震救援经验工作会议”。来自参加过地震救援的部分国家、阿尔及利亚和有关国际机构的代表共93人参加了会议。文章介绍了会议讨论的问题，包括灾害初期预警、动员和救援队的部署；现场协调；搜救工作和使用指南。最后，针对我国国际救援队的工作，提出具体建议。 相似文献
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Swail Val Alves Jose-Henrique Breivik Øyvind Brown Jennifer Greenslade Diana 《Ocean Dynamics》2019,69(4):513-517
Following the 1st International Workshop on Waves, Storm Surges and Coastal Hazards, which incorporated the 15th session of the long-standing the International Workshop on Wave Hindcasting and Forecasting, in September 2017 in Liverpool, United Kingdom, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 15 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. The continuing trend towards closer integration between the wave and ocean modeling communities is reflected in this workshop, culminating in the renaming of the workshop, while maintaining the connection with the three-decade long history of the wave workshop. This is also seen in this topical collection, with several papers exploring wave-generated storm surge, wave-tide contributions to coastal flooding, forcing a global ocean model with fluxes from a wave model and interaction between surface waves and sea ice.
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中国国际救援队指挥员代表团 《国际地震动态》2003,(3):24-28
2002年11月17日至12月5日中国国际救援队指挥员代表团赴欧洲参加了短期紧急救援指挥员培训，文章介绍了国际紧急技术中心的基本情况、培训内容和几点体会。 相似文献
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—?Seismic precursors to space shuttle re-entry shock fronts are detected at TXAR in Southwest Texas when the ground track of the orbiter vehicle passes within ～150–200?km of the observatory. These precursors have been termed “shuttle-quakes” because their seismograms superficially mimic the seismograms of small earthquakes from shallow sources. Analysis of the “shuttle-quake” seismograms, however, reveals one important difference. Unlike ordinary earthquakes, the propagation azimuths and horizontal phase velocities of the individual phases of the “shuttle-quakes” are functionally related. From a theoretical model developed to account for the origin of these precursors it is found that the seismic phases of “shuttle-quakes” are “bow” waves. A “bow” wave originates at the advancing tip of the shock front trace (i.e., intersection of the re-entry shock front with the surface of the earth) when the ground speed of the orbiter vehicle exceeds the horizontal phase velocity of a particular seismic phase. “Bow” waves are shown to differ in two important respects from the ordinary seismic phases. They vanish ahead of the advancing tip of the shock front trace and their propagation azimuths and horizontal phase velocities are functionally related. The ground speed of the orbiter vehicle exceeds the horizontal phase velocities of crustal seismic phase over much of the re-entry flight profile. As a result, P,S, and R g “bow” waves will be seen as precursors to the re-entry shock front at stations located within a few hundred km of its ground track. 相似文献
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《Journal of Atmospheric and Solar》2007,69(14):1668-1679
In the present study, we analyze the magnetospheric processes accompanied by midnight “pearls”— interval of pulsations of diminishing period (IPDP) sequence at the mid-latitude observatory Mondy (L=2.1). The pulsations were not obviously related to an individual substorm injection, but were generated at the time of intensification of magnetospheric convection. A “Wave-Particle Boiler” (WPB) model of the IPDP generation is used for the interpretation of the results obtained. 相似文献
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A combined magnetomineralogical analysis of a doleritic collection gathered from four natural outcrops in the mouth area of the Stolbovaya River revealed a spinodal pattern of the decomposition of a magnetite-ulvospinel solid solution (the stage of the “modulated structure” formation) in the ferromagnetic fraction of samples. Homogenization of exsolution structures during thermal treatment of the majority of the collected samples is shown to involve the effect of partial self-reversal of thermoremanent magnetization. A distinct dependence of the effect on the level of internal elastic stresses suggests that a reverse component of J n can arise during some phases of the spinodal stage of the solid solution decomposition in natural titanomagnetites. 相似文献
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On the classification of surface geoelectric arrays 总被引：1，自引：0，他引：1
We collected approximately one hundred independent geoelectric arrays from published geophysical literature. We have presented them in a systematic way and with a unified notation. The classification of arrays is based on three divalent parameters: “superposition” of measurements, “focusing” of currents and “colinearity” of the array, creating 8 classes of geoelectric arrays. Among the 102 independent arrays we found in the geophysical literature, we managed to classify 92 arrays in the aforementioned way. Ten further techniques fell beyond the proposed classification. The classification we propose may open the way to new geoelectric arrays, hopefully providing improving responses to the infinite variety of field problems we may face. It may bring to daylight, exclusively in a logical way, currently unused arrays. In searching new geoelectric arrays this paper helps to avoid rediscovering the discovered. Although it might be thought that the modern multielectrode systems will supersede all former arrays, such systematization is not only for historical and tutorial interests: some of the “old” arrays can be perhaps built into new multielectode systems, further enhancing their effectivity in the future. Finally, this collection of arrays establishes the possibility of systematic intercomparisons of arrays on the basis of various theoretical or practical aspects. 相似文献
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Kr and Xe were measured by a stepwise heating technique in three samples of a drill core in the “Minnesota” fragment of the Estherville mesosiderite. The cosmogenic78Kr/83Kr decreased from the “top” sample to the “bottom” sample(“top” = 0.163 ± 0.005, “bottom” = 0.151 ± 0.005) while the cosmogenic131Xe/126Xe ratio increased(“top” = 5.58 ± 0.35, “bottom” = 6.92 ± 0.17). Cosmic-ray track studies have shown that the “top” sample was indeed closer to the preatmospheric surface than the “bottom” sample by ～ 10 cm. This is the first direct evidence, in a sample of known geometry, that the cosmogenic131Xe/126Xe ratio increases as a function of depth, and as such, confirms the hypothesis that the lunar131Xe anomaly is a bona fide depth effect due to resonance neutron capture in130Ba. 相似文献
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It is shown that the source for numerous magma superflows (MSFs) with complex structures, whose traces have been identified in the Bering Sea (Melekestsev and Slezin, 2017), was regional mantle plume-like formations (or plumes). The magmatic material propagated from these for some hundreds of kilometers or farther along interfaces at different depths between crustal layers during n × 105 to n × 106 years. The long-continued generation and multi-portion structure of the MSFs is explained by slow pulsations in the rising jet of primary melt in the form of a beaded (“peristalsis-like”) structure of successive bulges (which we shall refer to as “magmons”), which float up as “asthenoliths” as the through flow in the channel becomes lower. The most extensive and longest MSFs were formed at the end of the Eocene through Oligocene, while the youngest and shortest flow was generated in the Pleistocene. 相似文献
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TONG HengMao WANG JianJun ZHAO HaiTao LI Bo HAO HuaWu WANG MingYang 《中国科学:地球科学(英文版)》2014,57(7):1595-1604
The activation coefficient equations in the"activation criterion of pre-existing weakness"are relatively complex and not easy to apply to specific applications.The relative activity of pre-existing weaknesses is often critical in geological analysis.The Mohr circle can be used only in two-dimensional stress analysis.By applying the"activation criterion of pre-existing weakness"and combining it with numerical analysis,we establish the correspondence between the pole(n,n)of a pre-existing weakness plane and its orientation in"Mohr space".As a result,the normal stress(n)and shear stress(n)of a pre-existing weakness plane can be readily expressed in Mohr space.Furthermore,we introduce the method and procedures for predicting the activation and relative activation of pre-existing weaknesses in Mohr space.Finally,we apply the Mohr space method and compare the predictions to sandbox modeling results and 3D seismic data.The results show that Mohr space can be used in stress analysis to estimate the activation of a pre-existing weakness in any triaxial stress state. 相似文献
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Joseph R. Smyth 《Earth and Planetary Science Letters》1974,24(2):262-270
X-ray single-crystal studies have been made of armalcolites from the 2–5-mm fraction of Apollo 17 soils 75082 and 78502. Two types of armalcolite, “ortho” and “para” have previously been distinguished on the basis of optical properties and crystal habit in the Apollo 17 samples. “Ortho”-armalcolite has the space group of pseudobrookite, Bbmm, and has cell dimensions: a = 9.743 (5); b = 10.001 (5); and c = 3.728 (2)Å. The crystal structure, refined from 582 symmetry-independent intensities, is ordered with Ti in the site with m symmetry and Mg and Fe in the site with mm symmetry. “Para”-armalcolite has space group Bbmm, cell dimensions: a = 9.712 (20), b = 9.997 (20), and c 3.735 (8)Å; and is structurally identical with “ortho”-armalcolite. The two crystals studied are similar but not identical in composition, but the slight compositional differences and identical structures do not warrant the use of separate mineral names. 相似文献
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Passive surface wave methods have gained much attention from geophysical and civil engineering communities because of the limited application of traditional seismic surveys in highly populated urban areas. Considering that they can provide high-frequency phase velocity information up to several tens of Hz, the active surface wave survey would be omitted and the amount of field work could be dramatically reduced. However, the measured dispersion energy image in the passive surface wave survey would usually be polluted by a type of “crossed” artifacts at high frequencies. It is common in the bidirectional noise distribution case with a linear receiver array deployed along roads or railways. We review several frequently used passive surface wave methods and derive the underlying physics for the existence of the “crossed” artifacts. We prove that the “crossed” artifacts would cross the true surface wave energy at fixed points in the f–v domain and propose a FK-based data selection technique to attenuate the artifacts in order to retrieve the high-frequency information. Numerical tests further demonstrate the existence of the “crossed” artifacts and indicate that the well-known wave field separation method, FK filter, does not work for the selection of directional noise data. Real-world applications manifest the feasibility of the proposed FK-based technique to improve passive surface wave methods by a priori data selection. Finally, we discuss the applicability of our approach. 相似文献
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Mahmoudi E Essid N Beyrem H Hedfi A Boufahja F Vitiello P Aissa P 《Marine pollution bulletin》2005,50(11):1197-1204
Anthropogenic inputs of crude and refined petroleum hydrocarbons into the sea require knowledge of the effects of these contaminants on the receiving assemblages of organisms. A microcosm experiment was carried out to study the influence of diesel on a free living nematode community of a Tunisian lagoon. Sediments were contaminated by diesel that ranged in concentration from 0.5 to 20 mg diesel kg−1 dry weight (dw), and effects were examined after 90 days. Gradual changes in community structure were revealed depending on the quantity of diesel administrated. In the medium (1 mg diesel kg−1 and 5 mg diesel kg−1 (dw)) and high (10 mg diesel kg−1, 15 mg diesel kg−1 and 20 mg kg−1 (dw)) treated microcosms, most univariate measures, including diversity and species richness, decreased significantly with increasing level of diesel contamination whereas nematode assemblage from the low treated microcosm (0.5 mg diesel kg−1 (dw)) remained unaffected. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the diesel treatments were varied: Chaetonema sp. was eliminated at all doses tested and seemed to be intolerant species to diesel contamination; Pomponema sp. and Oncholaimus campylocercoïdes were significantly affected at all diesel contamination levels but they were not eliminated, these species were categorized as “diesel-sensitive”; Hypodontolaimus colesi, Daptonema trabeculosum and Daptonema fallax which significantly increased respectively at 0.5, 1 and 5 mg diesel kg−1 (dw) concentrations and appeared to be “opportunistic” species at these doses whereas Marylynnia stekhoveni which increased at all high doses (10, 15 and 20 mg diesel kg−1 (dw)) seemed to be a “diesel-resistant” species. 相似文献
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Soil failure can be used for seismic protection of structures 总被引：2，自引：2，他引：0
I. Anastasopoulos G. Gazetas M. Loli M. Apostolou N. Gerolymos 《Bulletin of Earthquake Engineering》2010,8(2):309-326
A new seismic design philosophy is illuminated, taking advantage of soil “failure” to protect the superstructure. Instead of over-designing the foundation to ensure that the loading stemming from the structural inertia can be “safely” transmitted onto the soil (as with conventional capacity design), and then reinforce the superstructure to avoid collapse, why not do exactly the opposite by intentionally under-designing the foundation to act as a “safety valve” ? The need for this “reversal” stems from the uncertainty in predicting the actual earthquake motion, and the necessity of developing new more rational and economically efficient earthquake protection solutions. A simple but realistic bridge structure is used as an example to illustrate the effectiveness of the new approach. Two alternatives are compared : one complying with conventional capacity design, with over-designed foundation so that plastic “hinging” develops in the superstructure; the other following the new design philosophy, with under-designed foundation, “inviting” the plastic “hinge” into the soil. Static “pushover” analyses reveal that the ductility capacity of the new design concept is an order of magnitude larger than of the conventional design: the advantage of “utilising” progressive soil failure. The seismic performance of the two alternatives is investigated through nonlinear dynamic time history analyses, using an ensemble of 29 real accelerograms. It is shown that the performance of both alternatives is totally acceptable for moderate intensity earthquakes, not exceeding the design limits. For large intensity earthquakes, exceeding the design limits, the performance of the new design scheme is proven advantageous, not only avoiding collapse but hardly suffering any inelastic structural deformation. It may however experience increased residual settlement and rotation: a price to pay that must be properly assessed in design. 相似文献
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The aim of this study is to investigate the seismicity of Central Anatolia, within the area restricted to coordinates 30–35° longitude and 38–41° latitude, by determining the “a” and “b” parameters in a Gutenberg–Richter magnitude–frequency relationship using data from earthquakes of moment magnitude (Mw)?≥?4.0 that occurred between 1900 and 2010. Based on these parameters and a Poisson model, we aim to predict the probability of other earthquakes of different magnitudes and return periods (recurrence intervals). To achieve this, the study area is divided into six seismogenic zones, using spatial distributions of earthquakes greater than Mw?≥?4.0 with active faults. For each seismogenic zone, the a and b parameters in the Gutenberg–Richter magnitude–frequency relationship were calculated by the least squares method. The probability of occurrence and return periods of various magnitude earthquakes were calculated from these statistics using the Poisson method. 相似文献