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31.
Earthquake-induced landslides along the Dujiangyan-Yingxiu highway after the Ms 8.0 Wenchuan earthquake in 2008 were investigated.
It was found that: (1) slopes were shattered and damaged during the earthquake and open tension cracks formed on the tops
of the slopes; (2) the upper parts of slopes collapsed and slid, while the lower parts remained basically intact, indicating
that the upper parts of slopes would be damaged more heavily than the lower parts during an earthquake. 相似文献
32.
Hazel Matias-Peralta Fatimah Md. Yusoff Mohamed Shariff Aziz Arshad 《Marine pollution bulletin》2005,51(8-12):722
The effects of salinity, temperature, and light conditions on the reproduction and development of harpacticoid copepod, Nitocra affinis f. californica under controlled laboratory conditions were determined. Seven different salinity levels (5, 10, 15, 20, 25, 30, 35 ppt), four temperatures (20, 25, 30, 35 °C), three different light intensities (25, 56, 130 μmol m−2 s−1) and photoperiods (24 h:0 h, 1 h:23 h, 12 h:12 h LD cycle) were employed in this study. The highest (p < 0.05) overall reproduction and fastest development time were achieved by copepods reared under 30–35 ppt salinity. The optimum temperature required for the maximum reproduction was 30 °C while under 30 °C and 35 °C the copepod development time was shortest (p < 0.05) compared to other temperature levels. The overall reproduction was highest (p < 0.05) and development rate of N. affinis was shortest (p < 0.05) under lowest light intensity (25 μmol m−2 s−1). Continuous light (24 h:0 h LD) inhibited the egg production while, continuous darkness (1 h:23 h LD) and 12 h:12 h LD significantly favoured the overall reproductive activity of the female. Photoperiods 1 h:23 h and 12 h:12 h LD yielded highest total (p < 0.05) offspring female−1 coupled with highest (p < 0.05) survival percentage. This study illustrated that although N. affinis can tolerate wide range of environmental conditions, prolonged exposure to subnormal environments affect its reproduction and development. This study showed that this species can be mass cultured for commercial purposes and has a potential to be used for toxicity studies due to its high reproductive performance fast development and a wide range of tolerance to environmental conditions. 相似文献
33.
34.
Arshad Ali Iffat Jabeen Neil R. Banerjee Gordon R. Osinski Ian Nicklin David Gregory Patrick Herrmann 《Meteoritics & planetary science》2018,53(6):1223-1237
Oxygen isotope measurements of olivine in main group (MG) pallasites by traditional laser fluorination method are associated with some uncertainties including terrestrial weathering, incomplete olivine reaction, and sample state. We improved our laser fluorination approach by pretreating olivine grains with acid to remove terrestrial weathering products and by modifying the sample holder for an efficient and complete laser reaction. Our experiments on Brahin olivine demonstrate that acid-washing successfully removes the terrestrial weathering with <0.1‰ variation in δ18O value and, at the same time, improving the ∆17O value significantly. We also achieved a complete olivine fluorination by employing a custom-designed sample holder with “V”-shaped profile having rounded bottom because incomplete/partial reaction of olivine gives comparatively lighter δ18O values. Using these new techniques, we present precise triple oxygen isotope data (N = 72) of 25 olivine samples separated from main group pallasites. The data are, on average, ~0.5‰ heavier in δ18O relative to the values published in the literature for the same samples. Critically, the ∆17O values of MG pallasites and to some extent their Fo-contents suggest that there are at least two populations of olivine. Based on our improved data set, we propose that MG pallasites potentially have high-∆17O- and low-∆17O-bearing subgroups that are statistically distinct. The subgroups present average ∆17O values of −0.166 ± 0.003 (2SE; N = 16) and −0.220 ± 0.003 (2SE; N = 9), respectively. Furthermore, the high-∆17O-bearing subgroup samples trend toward lower Fo-contents compared to the other subgroup. Taken together, our data provide evidence that argues against a single parent body origin for MG pallasites. 相似文献
35.
Linear and nonlinear properties of coupled modes in a magnetized quantum plasma in the presence of electron Fermi pressure are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. Stationary solutions of the nonlinear equations that govern the dynamics of coupled modes are presented. It is found that electrostatic dipolar vortex structure can form in such a plasma. The dipolar structures in dense plasmas are observed to be formed on a much shorter scalelength by comparison with their classical counterparts. It is found that the increasing Fermi temperature shortens the scalelength over which the nonlinear coherent structures are formed. The relevance of the present investigation with regard to the dense astrophysical plasmas is also pointed out. 相似文献
36.
Many structures (including transmission-line towers, bridges, tall buildings and coastal structures) are founded on piles, which are designed to transmit both vertical and horizontal forces, and resulting moments, to the load bearing strata. The design of such foundations for large lateral repeating loads (e.g. caused by wind, wave action, earthquake) and lateral earth pressures is a challenging task. This paper presents an experimental study that investigates the use of concentric rings (CRs) of small diameter (displacement) piles (SDPs) surrounding a monopile installed in dry sand, with the intention of limiting its rotation (lateral displacement) under repeated lateral loading. The test results showed that the rotation of the monopile, investigated for a range of different repeated lateral loading schemes, was reduced by 35?75% on account of the densification of the sand achieved during installation of the SDPs and also the lateral confinement they provided to the sand located within the CRs. Significant increases to both the cyclic stiffness and load carrying resistance of the monopile under lateral loading are documented with the inclusion of the SDPs. Further experimental as well as numerical studies are necessary to validate this novel technique and to optimise the geometrical size and network pattern of the SDPs and the CRs. 相似文献
37.
Fahim Abul Kashem Faruki Rahman Md. Zillur Hossain Md. Shakhawat Kamal A. S. M. Maksud 《Natural Hazards》2022,113(2):933-963
Natural Hazards - Soil liquefaction resistance evaluation is an important site investigation for seismically active areas. To minimize the loss of life and property, liquefaction hazard analysis is... 相似文献
38.
Ashraf Muhammad Arshad Adnan Patel Praharsh M. Khan Adeel Qamar Huma Siti-Sundari Ristina Ghani Muhammad Usman Amin Ali Babar Jamilur Rehman 《Natural Hazards》2021,109(3):2127-2151
Natural Hazards - Climate change-induced disasters show the highest risk for agriculture and livelihoods in rural areas of developing countries. Due to changing rainfall pattern, the arid and... 相似文献
39.
Iffat Jabeen Minoru Kusakabe Keisuke Nagao Arshad Ali 《Meteoritics & planetary science》2019,54(2):431-451
Precise triple oxygen isotope compositions of 32 Allende bulk chondrules (ABCs) are determined using laser‐assisted fluorination mass spectrometry. Various chemically characterized chondrule types show ranges in δ18O that vary from ?4.80‰ to +1.10‰ (porphyritic olivine; PO, N = 15), ?3.10‰ to +1.50‰ (porphyritic olivine pyroxene; POP, N = 9), ?3.40‰ to +2.60‰ (barred olivine; BO, N = 4), and ?3.60‰ to +1.30‰ (porphyritic pyroxene; PP, N = 3). Oxygen isotope data of these chondrules yield a regression line referred to as the Allende bulk chondrule line (ABC line, slope = 0.86 ± 0.02). Most of our data fall closer to the primitive chondrule minerals line (PCM line, slope = 0.987 ± 0.013) and the carbonaceous chondrite anhydrous mineral line (CCAM line, slope = 0.94 ± 0.02) than the Allende anhydrous mineral line (AAML, slope = 1.00 ± 0.01) with a maximum δ18O value (+2.60‰) observed in a BO chondrule and a minimum δ18O value (?4.80‰) shown by a PO chondrule. Similarly, these chondrules depict variable ?17O values that range from ?5.65‰ to ?3.25‰ (PO), ?4.60‰ to ?2.80‰ (POP), ?4.95‰ to ?3.00‰ (BO), ?5.30‰ to ?3.20‰ (PP), and ?4.90‰ (CC). A simple model is proposed for the Allende CV3 chondrite with reference to the AAML and PCM line to illustrate the isotopic variations occurred due to the aqueous alteration processes. The estimated temperature ranging from 10 to 130 °C (mean ~60 °C) implies that the secondary mineralization in Allende happened in a warmer and relatively dry environment compared to Murchison. We further propose that thermal metamorphism could have dehydrated the Allende matrix at temperatures between >150 °C and <600 °C. 相似文献
40.
A large numbers of mountain communities in the Himalayan region depend on glacier-fed kuhl system – gravity flow irrigation, for their sustenance. The depletion and retreat of glaciers often result in disruption of melt flows to kuhl system, which ultimately impacts the agriculture as well as livelihood of the local communities. Sustainability of glacial resource was assessed for establishing kuhl irrigation system based on indices of glacier decrease by number(GDN) and glacier depletion by volume(GDV) during the 2001-2013 period. The selected factors are important in terms of understanding point source and reserve potential of glaciers for sustaining glacier-fed kuhl irrigation in this region. The sustainability of glaciers was found good(i.e. a least decrease or rather increase in glacier number and volume) in about 23.6% glaciers(ice reserves about 705.9 km~3) under 10 km~2 area class of glaciers mainly in Gilgit and Shigar river basins of the Karakoram range. In the 5–10 km~2 class of glaciers, sustainability was good in 49 glaciers(ice reserve 26.59 km~3) and under 1–5 km~2 class, in 558 glaciers(ice reserve 60.189 km~3). Overall sustainability of glaciers appears to prevail in the Karakoram basins. The lesser sustainability of glaciers in the Himalaya basins like Astore and Jhelum would apparently be compensated by monsoon and change in rainfall pattern. A regular monitoring of the glacier resource and utilizing advance water conservation techniques would help in coping with negative impacts of downwasting of glaciers and provide long-term support to kuhl irrigation system in the Himalayan region in future. 相似文献