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111.
Nasser Laouami Abdennasser Slimani Youcef Bouhadad Jean-Luc Chatelain Ali Nour 《Soil Dynamics and Earthquake Engineering》2006,26(11):991-1003
The Algiers–Boumerdes region has been struck by a destructive magnitude 6.8 (Mw) earthquake on May 21, 2003. The study presented in this paper is based on main shock strong motions from 13 stations of the Algerian accelerograph network. A maximum 0.58g peak ground acceleration (PGA) has been recorded at 20 km from the epicenter, only about 150 m away from a PGA of 0.34g, with both a central frequency around 5 Hz, explained by a strong very localized site effect, confirmed by receiver function technique results showing peaks at 5 Hz with amplitudes changing by a factor of 2. Soil amplifications are also evidenced at stations located in the quaternary Mitidja basin, explaining the higher PGA values recorded at these stations than at stations located on firm soil at similar distances from the epicenter. A fault-related directionality effect observed on the strong motion records and confirmed by the study of the seismic movement anisotropy, in agreement with the N65 fault plan direction, explains the SW–NE orientation of the main damage zone. In the near field, strong motions present a high-frequency content starting at 3 Hz with a central frequency around 8 Hz, while in the far field their central frequency is around 3 Hz, explaining the high level of damage in the 3- to 4-story buildings in the epicentral zone. The design spectra overestimate the recorded mean response spectra, and its high corner frequency is less than the recorded one, leading to a re-examination of the seismic design code that should definitively integrate site-related coefficient, to account for the up to now neglected site amplification, as well as a re-modeling of the actual design spectra. Finally, both the proposed Algerian attenuation law and the worldwide laws usually used in Algeria underestimate the recorded accelerations of the 6.8 (Mw) Boumerdes earthquake, clearly showing that it is not possible to extrapolate the proposed Algerian law to major earthquakes. 相似文献
112.
Summary The aim of this study is the evaluation of models that estimate daily global solar radiation on tilted surfaces from that
measured on horizontal surfaces. Global solar radiation incident on a tilted plane consists of three components: beam radiation,
diffuse radiation and reflected radiation from the ground.
The Klein (1977) method, modified by Andersen (1980), was used for estimating direct solar radiation incident on tilted surfaces
and an isotropic model was used for estimating reflected solar radiation incident on a tilted plane. In contrast models for
the diffuse radiation component show major differences, which justifies a validation study which has been done.
Eight models for derivation of daily slope diffuse irradiance from daily horizontal diffuse irradiance were tested against
recorded slope irradiances at Karaj (35°55′ N; 50°56′ E), Iran. The following models were included: Badescu (2002), Tian et
al. (2001), Reindl et al. (1990), Skartveit and Olseth (1986), Koronakis (1986), Steven and Unsworth (1980), Hay (1979) and
Liu and Jordan (1962).
All the models use the same method for calculating beam radiation as well as ground reflected radiation. However, only diffuse
component of radiation was compared. Statistical indices showed that Reindl’s model gives the most accurate prediction for
the south-facing surface and Koronakis’s model performs best for the west-facing surface. The Relative Root Mean Square Errors
(%RMSE), except for Steven and Unsworth’s model that has unacceptable results, for whole data range from 1.02 to 10.42%. In
general, Reindl’s model produces the best agreement with the measured tilted data. 相似文献
113.
114.
Chabazite-phillipsite tuff from Tell Rimah volcano was evaluated in industrial wastewater treatment. Samples of two different size fractions have suitable zeolite content and cation exchange capacity, and are characterized by good attrition resistance and high packed bed density. Such properties enable these fractions to be used as ion exchangers under column operation condition. In the presence of high concentration of competing ions, such as Na+, Ca+2 and K+, and under conditions of high total ionic concentration of toxic metals, the chabazite-phillipsite tuff exhibits successful performance in removing Cu+2, Cr+3, Ni+2, Zn+2 and Fe+2 from electroplating effluents. The factors that influence selectivity and efficiency of the zeolitic tuff were evaluated. The experimental work indicates that both selectivity and efficiency of the zeolite shows similar trends. The selectivity sequence exhibited by the zeolitic tuff is Ni+2>>Zn+2 and Cr+3>Cu+2>>Fe+2. 相似文献
115.
116.
Mabrouk SAMI Theodoros NTAFLOS Haroun A. MOHAMED Esam S. FARAHAT Christoph HAUZENBERGER Nasser M. MAHDY Khaled M. ABDELFADIL Douaa FATHY 《《地质学报》英文版》2020,94(3):763-776
A highly-fractionated garnet-bearing muscovite granite represents the marginal granitic facies of the Abu-Diab multiphase pluton in the Central Eastern Desert of Egypt. New electron microprobe analyses(EMPA) and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) data from garnets are reported, in order to constrain their origin and genesis. Garnet in the Abu-Diab host granite is euhedral to subhedral, generally homogeneous and, in rare cases, it shows weak zonation. The garnet contains appreciable amounts of MnO and FeO, with lesser amounts of MgO and CaO, yielding an end-member formula of Sps_(61–72)Alm_(25–35)Prp_(1–4)Adr_(0–1). Moreover, it is depleted in large ion lithophile elements(LILE) with lower values of Ba, Nb and Sr relative to the primitive mantle. Additionally, it contains high concentrations of HREE and Y and their REE pattern shows strong negative Eu anomalies. The garnet was crystallized under relatively low temperature(646°C–591°C) and pressure( 3 kbar) conditions. The textural and chemical features indicate that the garnet is magmatic in origin and is chemically similar to that from highly-fractionated A-type granite. It was probably formed at the expense of biotite in a highly-evolved MnO-rich magma and/or by hydroxyl complexing of Mn during the ascending fluid phases. 相似文献
117.
Nasser Mostafawi 《Environmental Geology》2001,40(10):1185-1191
Ostracods from 14 surface sediment samples taken from the northwest part of the Persian Gulf (Iranian side) at water depths of 32-54 m were studied to evaluate the environmental pollution caused by oil spills following the 1991 Gulf War. With the exception of two live ostracods, which show no response to the contamination, at least 58 closed carapaces from 18 taxa of herbivorous and sediment-feeding species were found containing dark brown oil. All contaminated specimens were restricted to the uppermost part of the sediments (0.0-0.5 cm). The extent of the impact and the number of affected species varies within the samples. The most heavily contaminated ostracods were encountered in samples 1, 3, 14, 21 and 26 in which 3-5% of the complete carapaces contain oil residues. Compared to a previous sampling in 1965, seven additional ostracod species occur in the modern Persian Gulf. This indicates an intact environmental state prior to the Gulf War. 相似文献
118.
A new constitutive model is developed for the mechanical behaviour of unsaturated soils based on the theory of hypoplasticity and the effective stress principle. The governing constitutive relations are presented and their application is demonstrated using several experimental data from the literature. Attention is given to the stiffening effect of suction on the mechanical response of unsaturated soils and the phenomenon of wetting‐induced collapse. All model parameters have direct physical interpretation, procedures for their quantification from test data are highlighted. Quantitative predictions of the model are presented for wetting, drying and constant suction tests. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
119.
120.
Catchment lithology as a major control on alluvial megafan development,Kohrud Mountain range,central Iran 总被引:1,自引:0,他引:1
Nasser Arzani 《地球表面变化过程与地形》2012,37(7):726-740
The relative importance of tectonics, climate, base level and source lithology as primary factors on alluvial‐fan evolution, fan morphology and sedimentary style remain in question. This study examines the role of catchment lithology on development and evolution of alluvial megafans (>30 km in length), along the flanks of the Kohrud Mountain range, NE Esfahan, central Iran. These fans toe out at axial basin river and playa‐fringe sediments towards the centre of basin and tectonics, climatic change and base‐level fluctuations, were consistent for their development. They formed in a tectonically active basin, under arid to semiarid climate and a long term (Plio‐Pleistocene to Recent) change from wetter to drier conditions. The key differences between two of these fans, Soh and Zefreh fans, along the west and south flanks of this mountain range, is that their catchments are underlain by dissimilar bedrock types. The source‐area lithologies of the Soh and Zefreh fans are in sedimentary and igneous terrains, respectively, and these fans developed their geometry mainly in response to different weathering intensities of their catchment bedrock lithologies. Fan surface mapping (based on 1/50000 topographic maps, satellite images, and fieldwork), reveals that the geomorphic evolution of these fans differs in that the relatively large‐scale incision and through trenching of the Soh fan is absent in the Zefreh fan. Whereas the limited sediment supply of the Soh fan has resulted in a deep incised channel, the Zefreh fan has remained aggradational with little or no trenching into proximal to medial fan surface due to its catchment bedrock geology, composed mainly by physically weathered volcaniclastic lithology and characterized by high sediment supply for delivery during episodic flash floods. Sediment supply, which is mainly a function of climate and source lithology, is a dominant driver behind the development of fan sequences in alluvial megafans. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献