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61.
Nicola Nocilla Aldo Evangelista Anna Scotto di Santolo 《Rock Mechanics and Rock Engineering》2009,42(5):815-833
In recent years, rock fall phenomena in Italy have received considerable attention for risk mitigation through in situ observations and experimental data. This paper reports the study conducted at Camaldoli Hill, in the urban area of Naples, and at Monte Pellegrino, Palermo, Italy. The rocks involved are volcanic Neapolitan yellow tuff (NYT) in the former area and dolomitic limestone in the latter. Both rocks, even though with different strength characteristics, have shown a significant tendency towards rock fragmentation during run out. This behavior was first investigated by comparing the volumes of removable blocks on the cliff faces (V 0) and fallen blocks on the slopes (V f). It was assumed that the ratio V f/V 0 decreases with the distance (x f) from the detachment area by an empirical law, which depends on a coefficient α, correlated with the geotechnical properties of the materials involved in the rock fall. Finally, this law was validated by observation of well-documented natural rock falls (Palermo) and by in situ full-scale tests (Naples). From the engineering perspective, consideration of fragmentation processes in rock fall modeling provides a means for designing low-cost mitigation measures. 相似文献
62.
Megan Gawith Roger Street Richard Westaway Anna Steynor 《Global Environmental Change》2009,19(1):113-121
The UKCIP02 climate change scenarios have become the standard reference for climate change in the UK since their release in 2002. This paper describes and reflects on the ways in which they have been applied. It then identifies some strengths, weaknesses and barriers to their application, and extracts key lessons that may inform the development and provision of future climate change scenarios.Analysis of the application of UKCIP02 shows that the scenarios have been used primarily as a communication device, as well as for scientific research and to inform policy and decision-making on climate change. They have played a critical role in raising awareness on climate change and in engaging organisations in the need to adapt. Their presentation in an accessible style, and their availability in a variety of formats, greatly facilitated their uptake. However, analysis has also revealed weaknesses which served as barriers to their uptake. Some of these, such as file format and accessibility issues, were readily overcome through technical solutions. Others, such as the issue of how to use uncertain information in decision-making, have only been partially addressed and remain an outstanding challenge for future scenario packages. Two key lessons have emerged which may benefit the provision of future climate scenarios in the UK and elsewhere. First, it is not enough to simply make climate change scenarios available. Their provision must be accompanied by ongoing guidance and support to ensure widespread and appropriate uptake. Second, on-going dialogue between those providing scenarios and the communities using them is fundamental to constructively meet the challenges associated with delivering credible scenarios that balance user requirements and expectations with what the science can deliver. 相似文献
63.
Anna M Nobili 《Celestial Mechanics and Dynamical Astronomy》1988,45(1-3):293-304
Modern computer technology allows dynamical astronomers to investigate the long term stability of real systems as thoroughly as ever. However, the process is not straightforward and new problems need to be solved. This work deals with only one such problem: the construction-from the numerical integration- of a secular perturbation theory that is able to describe the dynamical behavior of the system. The discussion refers to the outer planets and is based on the knowledge acquired by the author during her participation in project LONGSTOP. A digital filter is used in order to reduce the output and eliminate short periodic terms. Filtering uncovers long term variations in the semimajor axes. From the filtered output a secular perturbation theory is constructed in the assumption that the solution is regular, as secular perturbation theories can only be constructed for regular solutions. If we succeed, this means that the solution is indeed regular for the computed span of time; if not-and this can be established in a rigorous way-it has to be concluded a posteriori that the solution is not regular. The LONGSTOP 1A and 1B integrations show well that as the timespan of the integration increases it is possible to detect the non-regular behavior of the solution. This happens in the eccentricity of Saturn at the 10–4 level. 相似文献
64.
Natalia S. Bezaeva Dmitry D. Badyukov Mikhail A. Nazarov Pierre Rochette Joshua M. Feinberg Gennadiy P. Markov Daniel Borschneck François Demory Jérôme Gattacceca Sergey E. Borisovskiy Anna Ya Skripnik 《Meteoritics & planetary science》2014,49(6):958-977
Here we characterize the magnetic properties of the Chelyabinsk chondrite (LL5, S4, W0) and constrain the composition, concentration, grain size distribution, and mineral fabric of the meteorite's magnetic mineral assemblage. Data were collected from 10 to 1073 K and include measurements of low‐field magnetic susceptibility (χ0), the anisotropy of χ0, hysteresis loops, first‐order reversal curves, Mössbauer spectroscopy, and X‐ray microtomography. The REM and REM′ paleointensity protocols suggest that the only magnetizations recorded by the chondrite are components of the Earth's magnetic field acquired during entry into our planet's atmosphere. The Chelyabinsk chondrite consists of light and dark lithologies. Fragments of the light lithology show logχ0 = 4.57 ± 0.09 (s.d.) (n = 135), while the dark lithology shows 4.65 ± 0.09 (n = 39) (where χ0 is in 10?9 m3 kg?1). Thus, Chelyabinsk is three times more magnetic than the average LL5 fall, but is similar to a subgroup of metal‐rich LL5 chondrites (Paragould, Aldsworth, Bawku, Richmond) and L/LL5 chondrites (Glanerbrug, Knyahinya). The meteorite's room‐temperature magnetization is dominated by multidomain FeNi alloys taenite and kamacite (no tetrataenite is present). However, below approximately 75 K remanence is dominated by chromite. The metal contents of the light and dark lithologies are 3.7 and 4.1 wt%, respectively, and are based on values of saturation magnetization. 相似文献
65.
V2213 Cyg was discovered as a variable star by Pavlenko (1999) in 1998. We present our photometry of V2213 Cyg from 1998–2003
based on CCD observations with the K-380 Cassegrain telescope of CrAO and the 60 cm Zeiss telescope of SAI. Observations have
been carried out mostly in R and sometimes in B and V Johnson system. The total amount of data is 2270 points, covering ∼50 nights. We classify this binary as a W UMa-type contact
system. Using all data we determined the orbital period to be 0.350079 ± 0.000007 day. The mean brightness varies between
R = 14.35 and 14.05. The mean 1999–2003 orbital light curve has two humps and a primary minimum (I), which is 0.04 mag brighter
than the deeper secondary one (II). The mean humps have slightly different height. The difference between two individual maxima
varies within 0.1 mag, which may indicate an activity of the components. The highest hump is an asymmetrical one: it has sort
of a shoulder at phases 0.75–0.80, before entering the less deep primary minimum (phase 0.0). The system is rather reddened,
its colour indices are: B−V ∼ 0.8 and V−R ∼ 0.7, and give a spectral class of V2213 Cyg earlier than K. 相似文献
66.
Vladimir A.SANKOV Anna V.PARFEEVETS Andrey I.MIROSHNITCHENKO Aleksey V.SANKOV Amgalan BAYASGALAN Sodnomsambuu DEMBEREL 《地学前缘》2022,29(1):245-265
阿穆尔板块西部边界在蒙古境内的空间位置尚不清楚,并且活动断层构造及其沿线地壳的应力状态研究较少。本文在沿此边界的三个区域——杭爱—肯特构造鞍部、布尔古特地块(鄂尔浑—土拉交汇处)和色楞格地块(包括色楞格凹陷和布伦—努鲁隆起),利用空间图像解译、地形起伏度分析、地质构造资料以及构造压裂和沿裂缝位移资料重建构造古应力,对活动断层进行研究。研究表明,活动断裂继承了古生代和中生代古构造的非均质性。这些断层沿着板块边界并不是单一的带,而是成簇的。它们的运动取决于走向:亚纬向断层是具有一定逆分量的左旋走滑断层,北西向断层是逆断层或逆冲断层,通常具有右旋走滑分量,海底断层是右旋走滑断层,北东向断层是正断层。位于色楞格凹陷和杭爱东部的断裂构造的活动始于上新世。逆断层和走滑断层与上新世情况不符,但多与更新世地貌相符,表明其活动年代较晚,为更新世时期。利用构造断裂和沿断裂的位移,重建活动断裂带变形末阶段的应力应变状态,结果表明断裂在最大挤压轴的北北东和北东方向上以压缩和走滑为主。只有在色楞格凹陷内,以扩张和走滑类型的应力张量为主,且在最小挤压轴的北西走向尤为显著。在南部,杭爱东部(鄂尔浑地堑)内有1个以扩张机制为主的局部区域,说明蒙古中部断裂在更新世—全新世阶段的活动以及现代地震活动主要受与印度斯坦和欧亚大陆汇聚过程相关的东北方向的附加水平挤压的控制。使研究区地壳产生走滑变形、贝加尔湖裂谷发散活动以及阿穆尔板块东南运动的另一个因素是东南方向软流圈流动对岩石圈底部的影响。阿穆尔板块和蒙古地块之间的边界在构造结构上是零碎的,代表了覆盖整个蒙古西部变形带的边缘部分。 相似文献
67.
Shana Watanabe Anna Metaxas Jessica Sameoto Peter Lawton 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2235-2248
Deep-water corals form unique ecosystems, yet very little is known about factors that regulate their distribution and growth. The abundance and size of two deep-water gorgonian coral species, Paragorgia arborea and Primnoa resedaeformis, and their relationship with depth and substratum cover, were investigated at Northeast Channel, off Nova Scotia, in July 2006. This is the first study to measure abundance and size of these two coral species at depths >500 m in the Canadian Atlantic region. A total of 5 transects between 500 and 1000 m depth were examined using video collected by the remotely operated vehicle ROPOS. Abundance of both species was patchy, but higher at these deeper depths than at <500 m. Abundance generally declined with depth, and was moderately correlated with cover of hard substratum (cobble, boulder, bedrock). These relationships were stronger and less variable for P. resedaeformis than for P. arborea, suggesting that factors such as topographic relief may play an additional role in regulating distributions of P. arborea. Maximum colony height was 125 and 240 cm for P. resedaeformis and P. arborea, respectively, and much greater than recorded for depths <500 m. Overall, colony height and depth relationships were strong for both species, but variable among transects. P. resedaeformis showed a negative relationship with depth, while the opposite was observed for P. arborea, suggesting that the two species are affected differently by factors that vary with depth (e.g. temperature, fishing disturbance). Relationships between colony size and size of attachment stone were stronger for P. arborea, especially for overturned colonies, than for P. resedaeformis, suggesting that availability of suitably coarse substrate may be more important for the long-term persistence of P. arborea colonies. 相似文献
68.
ABSTRACTThe Australian government’s proposal to expand the Snowy Hydro Scheme to include a second pumped hydro energy storage (PHES) system, and support for feasibility studies for PHES in Tasmania, offer an opportunity to incorporate more intermittent renewable energy generation into the National Energy Market. However, the infrastructure construction required for PHES expansion may have negative effects for biodiversity in subalpine and alpine areas. To identify the potential effects of PHES on biodiversity in Kosciuszko National Park (KNP), this systematic literature review assesses: (i) the key environmental disturbances likely to arise from PHES construction; and (ii) the specific impacts of these construction processes on biodiversity in subalpine and alpine environments. We find that the effects of PHES construction-related disturbances are likely to be negative for subalpine and alpine biodiversity, with impacts including the proliferation of exotic flora, habitat loss resulting from vegetation clearing, altered landscape hydrology and reduced water quality. Management recommendations to limit these impacts are provided and further research is recommended to assess: (i) the effects of PHES on fish populations in alpine reservoirs; (ii) the utility of spoil as artificial habitat for endemic fauna; and (iii) the chemical and physical impacts of spoil dumping in alpine reservoirs. 相似文献
69.
Tina-Simone Neset Tomasz Opach Peter Lion Anna Lilja Jimmy Johansson 《The Professional geographer》2016,68(1):103-114
This article discusses the state of the art in geovisualization supporting climate change adaptation. We reviewed twenty selected map-based Web tools, classified by their content and functionality, and assessed them by visual representations, interactive functions, information type, target audience, and how vulnerability and adaptation to climate change are addressed. Our study concludes that the tools (1) can be classified as data viewers with basic functionality and data explorers offering more sophisticated interactive functions; (2) mostly feature moderate or high richness of data content; and (3) predominantly target expert users. 相似文献
70.
María Luisa Ávila-Jiménez Stephen J. Coulson Torstein Solhøy & Anna Sjöblom 《Polar research》2010,29(1):127-137
There are over 500 species of arthropods recorded from Svalbard. These animals overwinter either within the soil or on the ground surface, and have to tolerate an environment where the ground is frozen for over 9 months each year. Three cold-tolerance strategies have been described from Svalbard invertebrates: freeze avoidance, freeze tolerance and desiccation. Once in a cold-tolerant state the animals can be extremely cold tolerant in terms of both minimum exposure temperature and period of exposure. How the overwintering capabilities of these animals will be affected by climate changes during the next 100 years, as predicted by climate models, is not yet known. Four principle factors with an impact on overwintering of the terrestrial arthropod fauna are outlined here: (1) warmer winter temperatures, with an increased frequency of extreme events such as freeze–thaw cycles and surface icing; (2) changes in snow fall and snow lie; (3) pollutant load; and (4) dispersal of invertebrates to Svalbard. Finally, areas where further research is required are highlighted: including the development of controlled multi-season field experiments; effect of freeze–thaw cycles; changes in thickness and distribution of snow lie, with the subsequent effects on duration of the summer period; chill susceptibility of soil arthropods; assessing potential colonizing species and the likelihood of these species becoming established; assessing the effect of gene flow from surrounding populations; interactions between pollution and cold tolerance; anoxia stress; and the genetics of cold tolerance. 相似文献