Magnetic Resonance Imaging of Nonaqueous Phase Liquid Distribution in Unconsolidated Soils Using Discriminatory Freezing     

Saeed Kiaalhosseini  Benjamin Kohn  A. Ted Watson  Tom C. Sale  Jens Blotevogel 《Ground Water Monitoring & Remediation》2019,39(2):71-75

Organic contaminants present as nonaqueous phase liquids (NAPLs) in the subsurface often pose a long-term risk to human health and the environment. Investigating the distribution of NAPLs in porous media remains a major challenge in risk assessment and management of contaminated sites. Conventional soil coring and monitoring wells have been widely used over past decades as the primary means of subsurface investigation to determine NAPL extent. Known limitations of conventional approaches have led us to explore an alternative or a complementary technique to provide high-quality information of NAPL source zone architecture. This work advances an imaging tool for a variety of organic NAPL contaminants in unconsolidated soils through magnetic resonance imaging (MRI) of frozen cores. Using trichloroethylene (TCE) and o-xylene as model species, we illustrate that discriminatory freezing of water, while keeping the NAPL in a liquid state, enables high-resolution qualitative delineation of NAPL distribution within porous media. This novel approach may help improve site conceptual models and consequentially lead to highly tailored, more efficient remedial measures.  相似文献   

The plurality effect of topographical irregularities on site seismic response     

Jahromi  Saeed Ghaffarpour  Karkhaneh  Sama 《地震工程与工程振动(英文版)》2019,18(3):521-534

Topography can have significant effects on seismic ground response during an earthquake because topographic irregularities cause considerable differences between the seismic waves emitted by the source and the waves reaching the ground surface. When a seismic motion happens in a topographically irregular area, seismic waves are trapped and reflected between the topographic features. Therefore, the interaction between topographies can amplify seismic ground response. In order to reveal how interaction between topographies influences seismic response, several numerical finite element studies have been performed by using the ABAQUS program. The results show that topographic features a greater distance between the seismic source and the site would cause greater seismic motion amplification and is perceptible for the hills far away from the source and the ridges. Also, site acceleration response is impacted by surrounding topography further than site velocity and displacement response.  相似文献   

Evaluation of sediment contamination in the Red Sea coastal area combining multiple pollution indices and multivariate statistical techniques     

Yousef Saeed Saleh 《国际泥沙研究》2021,36(2):243-254

In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen's Red Sea coast sediment and identifies the possible sources of pollution.The concentrations of five metals(copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),and nickel(Ni))collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS).Sediment quality indices,such as the sediment quality guidelines(SQGs),potential ecological risk(RI),contamination factor(CF),pollution load index(PLI),geoaccumulation index(Igeo),and modified degree of contamination(mCd)were computed.In addition,multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis,and Pearson's correlation analysis)were applied to identify the potential sources of metals.The mean concentrations of Cu,Zn,Cd,Pb,and Ni were 51.3,61.9,4.02,9.9,and 33.4 mg/kg dry wt,respectively.The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city.According to the SQGs,the adverse biological effects of metals were occasionally associated with Cu and Cd,frequently associated with Ni,and not expected to occur with Zn and Pb.The RI indicated that the sediment of the studied sites pose low(RI<50)to considerable(100≤RI<200)ecological risk.The mean effect range-median quotient(M-ERM-Q)indicated that the combination of the studied metals had the toxicity probability of 21%at all studied sites.Igeo and CF indicated that the metals concentrations were in the descending order of:Zn>Ni>Pb>Cd>Cu,whereas the PLI and mCd indicated that Ras Isa(Site 5)and Urj village(Site 6)were the most polluted sites.PCA,cluster analysis,and correlation analysis found that Cd,Pb,and Ni mostly originated from anthropogenic sources while Cu and Zn were mainly derived from natural sources.Thus,it is evident that the intensive anthropogenic activities had negative influence on metals accumulation in the sediment of the Red Sea coast of Yemen leading to detrimental effects to the whole ecosystem.These comprehensive findings provide valuable information and data for future monitoring studies regarding heavy metals pollution and sediment quality at the Red Sea coast of Yemen.  相似文献   

Timing of Late Neoproterozoic glaciation on Baltica constrained by detrital zircon geochronology in the Hedmark Group, south-east Norway     

B. Bingen  W. L. Griffin  T. H. Torsvik  A. Saeed 《地学学报》2005,17(3):250-258

The Moelv Tillite is the Late Neoproterozoic Varanger glacial deposit recorded in the Hedmark Group, SE Norway. Paired U–Pb and Lu–Hf data collected on detrital zircons in the Rendalen Formation underlying the Moelv Tillite have identified an uncommon 677 ± 15 to 620 ± 14 Ma population, that constrain the deposition of the Moelv Tillite to be younger than 620 ± 14 Ma. The youngest detrital zircons may be derived from granite magmatism related to the 616 ± 3 Ma Egersund dolerite magmatism, situated in the western part of the Sveconorwegian orogen. The Moelv Tillite, which is not overlain by a cap carbonate, possibly correlates with the c. 580 Ma Squantum-Gaskiers glacial deposits of Avalonia. Available palaeomagnetic data for the Late Neoproterozoic suggest that Baltica was located at intermediate to high latitude between 620 and 555 Ma.  相似文献   

The social and physical vulnerability assessment of old texture against earthquake (case study: Fahadan district in Yazd City)     

Saeed Fallah Aliabadi  Alireza Sarsangi  Ehsan Modiri 《Arabian Journal of Geosciences》2015,8(12):10775-10787

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Solving land-use suitability analysis and planning problem by a hybrid meta-heuristic algorithm     

Kaveh Khalili-Damghani  Bahram Aminzadeh-Goharrizi  Saeed Rastegar  Babak Aminzadeh-Goharrizi 《International journal of geographical information science》2014,28(12):2390-2416

The aim of Land-use Suitability Analysis and Planning Problem (LSAPP) is to identify the most suitable parcels of land for future land-uses considering several conflicting criteria. LSAPP can be modeled using a variant of a well-known combinatorial optimization problem called Quadratic Assignment Problem (QAP). In this paper, a multi-objective mathematical model is developed for LSAPP based on QAP modeling. The large-size instances of the proposed multi-objective mathematical model are difficult to solve in a reasonable CPU time using exact algorithms. So, an efficient three-phase hybrid solution procedure is proposed. In the first phase, the compensatory objectives are integrated using Analytic Hierarchy Process (AHP) and Decision-Making Trial and Evaluation Laboratory. Then, based on the aforementioned suitability objective function and other spatial objectives and constraints, a multi-objective LSAPP is constructed. Finally, a hybrid multiple objective meta-heuristic algorithm is proposed to solve the LSAPP. The core of the proposed algorithm is based on Scatter Search while Tabu Search and Variable Neighborhood Search are also utilized. The proposed algorithm is equipped with the concepts of Pareto optimality and Veto Threshold, which improve its efficacy. The proposed algorithm is applied on a real LSAPP case study, in ‘Persian Gulf Knowledge Village’, wherein its performance is compared with a well-known evolutionary computation algorithm called Vector Evaluated Genetic Algorithm (VEGA) using comprehensive statistical analysis. A survey on time complexity of the proposed algorithm is also accomplished. The results show that MOSVNS is significantly superior to VEGA both in single and in multi-objective modes. Furthermore, analysis of time complexity of the proposed algorithm shows that it is of polynomial time and can be applied to significantly larger problems with multiple compensatory and non-compensatory objectives.  相似文献   

Optical and physical characterization of ��Iraqi freedom�� dust storm, a case study     

Thuraya M. Saeed  Hassan Al-Dashti 《Theoretical and Applied Climatology》2011,104(1-2):123-137

Kuwait was exposed to a severe dust storm on 19 March 2003, the eve of operation ??Iraqi Freedom??. Three days of dust events (19, 26, 27 March) were analyzed for their aerosol optical and physical properties using ground-based and satellite-retrieved measurements. Ground-based measurements of aerosol optical depth (or thickness; AOD or AOT) at 675?nm, ?? ₆₅₇, ?ngstrom coefficient ?? _936/657, particulate matter of diameter 10???m or less, PM₁₀ (??g/m³), and meteorological parameters were analyzed for March 2003. AOT exceeded 3 for the 3?days of interest and PM₁₀ concentrations reached as high value as 2,457???g/m³ on 19 March dust storm day. Retrieved aerosol characteristics from space using Moderate Resolution Imaging Spectrometer (MODIS) on board Terra and Aqua satellite were examined against ground-based measurements. A strong correlation was found between ground-based measurements of ?? ₆₇₅ and the Terra-MODIS retrieved AOD₅₅₀. The synoptic of the dust storm were analyzed and source regions were identified using back trajectory analysis and Total Ozone Mapping Spectrometer Aerosol Index.  相似文献   

Probabilistic seismic hazard assessment for Thailand   总被引：3，自引：1，他引：2  

Teraphan Ornthammarath  Pennung Warnitchai  Kawin Worakanchana  Saeed Zaman  Ragnar Sigbj?rnsson  Carlo Giovanni Lai 《Bulletin of Earthquake Engineering》2011,9(2):367-394

A set of probabilistic seismic hazard maps for Thailand has been derived using procedures developed for the latest US National Seismic Hazard Maps. In contrast to earlier hazard maps for this region, which are mostly computed using seismic source zone delineations, the presented maps are based on the combination of smoothed gridded seismicity, crustal-fault, and subduction source models. Thailand’s composite earthquake catalogue is revisited and expanded, covering a study area limited by 0°–30°N Latitude and 88°–110°E Longitude and the instrumental period from 1912 to 2007. The long-term slip rates and estimates of earthquake size from paleoseismological studies are incorporated through a crustal fault source model. Furthermore, the subduction source model is used to model the megathrust Sunda subduction zones, with variable characteristics along the strike of the faults. Epistemic uncertainty is taken into consideration by the logic tree framework incorporating basic quantities, such as different source modelling, maximum cut-off magnitudes and ground motion prediction equations. The ground motion hazard map is presented over a 10 km grid in terms of peak ground acceleration and spectral acceleration at 0.2, 1.0, and 2.0 undamped natural periods and a 5% critical damping ratio for 10 and 2% probabilities of exceedance in 50 years. The presented maps give expected ground motions that are based on more extensive data sources than applied in the development of previous maps. The main findings are that northern and western Thailand are subjected to the highest hazard. The largest contributors to short- and long-period ground motion hazard in the Bangkok region are from the nearby active faults and Sunda subduction zones, respectively.  相似文献   

Vulnerability of ordinary moment resistant concrete frames     

Mohammad Barkhordary  Saeed Tariverdilo 《地震工程与工程振动(英文版)》2011,10(4):519-533

The effects of structural modeling (bar slip in lap splice), ground motion selection process (epsilon effect) and size of a structure (number of bays and stories) on the fragility of reinforced concrete ordinary moment resisting frames are investigated. An analytical model is developed to account for bar slip in lap splice, which exhibits good correlation with existing experimental data. Then, incremental dynamic analysis is used to derive the fragility curves for four model structures. The model structures simulate frames with a different number of bays and stories. Finally, the fragility curves are corrected for the epsilon effect. The results show that slip in the lap splice can significantly increase the failure probability, especially for the collapse prevention limit state. At the same time, it is found that spectral shape has a significant impact on the fragility curves. It is also found that accounting for or ignoring bar slip or epsilon effects increases the probability of failure for larger structures. This indicates an unconservative bias in the safety of larger structures.  相似文献   

Lithostratigraphic subdivision of the Kuhlan Formation in Yemen     

Mohammed Al-Wosabi  Saeed Wasel 《Arabian Journal of Geosciences》2011,4(7-8):1323-1335

The lithostratigraphic subdivision of the Kuhlan Formation in Yemen is reviewed based on the previous literature and new examination of five widely spaced outcrops in the Kuhlan Affar, Jabal Maswar, Jabal Salab, Wadi Hajar, and Ras Falanj areas. Following the guidelines set by the North American Commission on Stratigraphic Nomenclature, Kuhlan Formation, with an age as latest Triassic to the Middle Jurassic, includes three members, Azzan, Souq, and Hesn, in an ascending order. Azzan member consists mainly of about 40 m of whitish coarse grained sandstone with many conglomeratic horizons. The Souq member is characterized by its reddish to brownish sandstones as well as the presence of polygonal structures at in the central part of this member, with a thickness of about 70 m. The Hesn member consists dominantly (80 m) of whitish sandstones with some marl intercalations at its topmost part. The Kuhlan Formation was deposited in a fluviatile environment.  相似文献