Out‐of‐plane seismic behaviour of rocking masonry walls     

Omar Al Shawa  Gianmarco de Felice  Alberto Mauro  Luigi Sorrentino 《地震工程与结构动力学》2012,41(5):949-968

The evaluation of the out‐of‐plane behaviour of unreinforced walls is one of the most debated topics in the seismic assessment of existing masonry buildings. The discontinuous nature of masonry and its interaction with the remainder of the building make the dynamic modelling of out‐of‐plane response troublesome. In this paper, the results of a shaking table laboratory campaign on a tuff masonry, natural scale, U‐shaped assemblage (façade adjacent to transverse walls) are presented. The tests, excited by scaled natural accelerograms, replicate the behaviour of external walls in existing masonry buildings, from the beginning of rocking motion to overturning. Two approaches have been developed for modelling the out‐of‐plane seismic behaviour: the discrete element method and an SDOF analytic model. Both approaches are shown to be capable of reproducing the experimental behaviour in terms of maximum rotation and time history dynamic response. Finally, test results and numerical time history simulations have been compared with the Italian seismic code assessment procedures. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Biocontrol of Meloidogyne javanica on Tomato Plants by Hypocrea lixii (the Teleomorph of Trichoderma harzianum)          下载免费PDF全文

Abdallah M. Elgorban  Mohamed A. Abdel‐Wahab  Ali H. Bahkali  Basheer A. Al‐Sum 《洁净——土壤、空气、水》2014,42(10):1464-1469

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Biocontrol of Meloidogyne javanica on Tomato Plants by Hypocrea lixii (the Teleomorph of Trichoderma harzianum)          下载免费PDF全文

Abdallah M. Elgorban  Mohamed A. Abdel‐Wahab  Ali H. Bahkali  Basheer A. Al‐Sum 《洁净——土壤、空气、水》2014,42(11):1660-1660

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Dynamic Treatment Response of Olive Mills Wastewater Using Series of Adsorption Steps     

Mohammed‐Osama J. Azzam  Kamal Al‐Malah  Ziad Al‐Gazzawi  Saad A. Al‐Omari 《洁净——土壤、空气、水》2010,38(9):822-830

Olive mills wastewater (OMW) is a critical environmental problem in the Mediterranean area due to its extremely high levels of COD and phenols. In this study, a group of adsorption experiments were conducted to investigate the dynamic response of the pH, COD, phenols, TSS, TDS, and TS concentrations of pretreated OMW, using different concentrations of activated carbon as adsorbent. The pretreatment included sedimentation and filtration of OMW. The pretreated OMW was then subjected to adsorption. A series of adsorption steps in stirred batch vessels were studied, namely, one stage, two‐stage countercurrent, and three‐stage countercurrent adsorption systems. A combined two‐ two‐stage countercurrent adsorption steps were also studied. Experimental results showed that such treatment protocols were promising. For example, a treatment protocol composed of a three‐stage countercurrent adsorption process using activated carbon of concentration of 24 g/L of OMW was able to reduce the COD from 60 000 mg/L down to 22 300 mg/L, while phenols were reduced from 450 to 15 mg/L.  相似文献   

Free Amino Acids Content in Some Halophytes under Salinity Stress in Arid Environment,Jordan     

Farah Al Nasir  Mufeed Batarseh  Adel H. Abdel‐Ghani  Anwar Jiries 《洁净——土壤、空气、水》2010,38(7):592-600

The variation in free amino acids concentration was examined in halophytes under salt stress conditions during spring and autumn in an arid environment, Jordan. The experiment was conducted in the southern region of the Jordan valley, using four different halophytes namely: Atriplex halimus, Atriplex nummularia, Tamarix aphylla L., and Portulaca oleracea L. Free amino acid concentrations showed changeable patterns under salinity stress conditions compared to the non‐stress (control) with respect to plant species and seasonal variation. In general, the amino acid pool during the spring experienced increases in A. halimus with increasing salinity; and decreased in A. nummularia, P. oleracea L., and T. aphylla L., respectively. Whereas, during the autumn, the overall amino acids decreased in A. halimus and A. nummularia, and increased in T. aphylla L. and P. oleracea with increasing salinity. The amino acid pool concentrations of A. halimus L. during the autumn was similar to that in spring under stress condition. Similarly, T. aphylla L. and P. oleracea showed higher rates in the autumn. In contrast, A. nummularia L. exhibited a slight increase in amino acid composition in the autumn under stress conditions. The plantation of salt tolerant plants such as halophytes in saline sodic soils showed an effective decline in soil salinity and can be recommended to be used as a bioreclamation method instead of the traditional leaching method, which requires large amount of fresh water.  相似文献   

A ∼33,000 year record of environmental change from Arolik Lake, Ahklun Mountains, Alaska, USA     

Darrell S. Kaufman  Feng Sheng Hu  Jason P. Briner  Al Werner  Bruce P. Finney  Irene Gregory-Eaves 《Journal of Paleolimnology》2003,30(4):343-361

A continuous record of lacustrine sedimentation capturing the entire full-glacial period was obtained from Arolik Lake in the Ahklun Mountains, southwestern Alaska. Fluctuations in magnetic susceptibility (MS), grain size, organic-matter (OM) content, C/N ratios, ¹³C, and biogenic silica (BSi) record marked environmental changes within the lake and its watershed during the last 33 cal ka. Age control is provided by 31 ¹⁴C ages on plant macrofossils in four cores between 5.2 and 8.6 m long. Major stratigraphic units are traceable throughout the lake subbottom in acoustical profiles, and provisional ages are derived for six prominent tephra beds, which are correlated among the cores. During the interstadial interval between 33 and 30 cal ka, OM and BSi contents are relatively high with values similar to those of the Pleistocene–Holocene transition, suggesting a similar level of aquatic productivity. During the glacial interval that followed (30–15 cal ka), OM and BSi decrease in parallel with declining summer insolation. OM and BSi values remain relatively uniform compared with the higher variability before and after this interval, and they show no major shifts that might correlate with climate fluctuations evidenced by the local moraine record, nor with other global climate changes. The glacial interval includes a clay-rich unit with a depauperate diatom assemblage that records the meltwater spillover of an ice-dammed lake. The meltwater pulse, and therefore the maximum extent of ice attained by a major outlet glacier of the Ahklun Mountain ice cap, lasted from 24 to 22 cal ka. The Pleistocene–Holocene transition (15–11 cal ka) exhibits the most prominent shifts in OM and BSi, but rapid and dramatic fluctuations in OM and BSi continue throughout the Holocene, indicating pronounced paleoenvrionmental changes.  相似文献   

The Use of Ambient Seismic Noise Measurements for the Estimation of Surface Soil Effects: The Motril City Case (Southern Spain)     

Z. Al Yuncha  F. Luzón  A. Posadas  J. Martín  G. Alguacil  J. Almendros  S. Sánchez 《Pure and Applied Geophysics》2004,161(7):1549-1559

This paper presents a study of the ambient seismic noise features in Motril City. The predominant resonant period at each site was determined using the Horizontal to Vertical Noise Ratio (HVNR) of the microtremors records; it was applied to 91 points which cover the city and we present the distribution of the periods over a map which shows important characteristics requiring consideration in a study focussing on the mitigation of the seismic risk. Using these results, two zones can be distinguished: north of the GG profile with predominant periods smaller than 0.25 sec which corresponds with a hard soil, and south of GG with periods ranging from 0.25 to 0.6 indicating a medium-soft soil. Microtremors are a preliminary useful tool that compensates for the lack of seismic recorded data, and that can complement other valuable information (borehole logs, geology, etc.) to evaluate the seismic risk on places as Motril City where some of this information is unavailable. Through the predominant period the HVNR indicates the kind of soil we are dealing with.  相似文献   

A general view on the activity in the field of mathematical geology in Romania     

Cristina Dumitriu  Al. Dimitriu 《Mathematical Geology》1970,2(3):333-334

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Assessment of organic pollutants in the offshore sediments of Dubai, United Arab Emirates     

H. A. Al Darwish  E. A. Abd El-Gawad  F. H. Mohammed  M. M. Lotfy 《Environmental Geology》2005,48(4-5):531-542

Fifteen stations (st) were selected along Dubai coastal region to delineate the distribution and the source of total petroleum hydrocarbon (TPH), total organic carbon (TOC), total Kjeldhal nitrogen (TKN), polycyclic aromatic hydrocarbon (PAHs) and polychlorinated biphenyls. The concentrations of TPH fluctuated between 2 μg g ⁻¹ and 48018 μg g ⁻¹ and the values of TOC were in the range of 0.16–5.9 wt%, while TPAHs ranged from 0.09 μg g ⁻¹ to 161.72 μg g ⁻¹. On the other hand, TPCBs showed values between 0.8 μg kg⁻¹ and 93.3 μg kg⁻¹ and TKN values varied from 218 μg g⁻¹ to 2457 μg g ⁻¹. Distribution of oil and organic compounds in Dubai sediments are safe compared with previous studies except for limited areas at the northeastern offshore. These readings are probably due to: (1) presence of commercial or industrial ports, dry docks and fishing harbours and (2) population centers mainly concentrated at the northern part of the study area. Results indicate that TOC can be used as indicator of oil pollution only in heavily oiled sediments. The highest values of TOC, TPH, TPAHs and TPCBs corresponded to the stations covered with fine sand, due to adsorption properties and larger surface area. The evaporation of low boiling point compounds from surface layers led to enrichment of sediments with the thick residual. Al-Hamriya St 3 exhibited the highest values of TPH, TOC, TPAHs and TPCBs and the second highest value of TKN.  相似文献   

The role of volcanic eruptions in blocking the drainage leading to the Dead Sea formation     

Elias Salameh  Mohammed Al Farajat 《Environmental Geology》2007,52(3):519-527

The shrinkage of the Lisan Lake (LL) to form the recent Dead Sea (DS) was mainly a result of the reduction of the catchment area from around 157,000 km² during Late Pleistocene to 43,000 km² presently. The reduction in the catchment area resulted from the eruption and spread of the basalt flows of Jabal Arab-Druz (JAD), which together with the resulting deposition of thick rock debris and gravels occupied the drainage system. The filling of the pre-basalt drainage system, which used to feed the Dead Sea, with basalts and alluvial sediments blocked the inflows from reaching the Dead Sea. Local base levels along the basalt flow boarders such as Azraq Oasis, Sirhan Basin and Damascus Oasis, and numerous pools and mud flats were created.  相似文献