Climate change impact on river flows and catchment hydrology: a comparison of two spatially distributed models     

Thomas Vansteenkiste  Mohsen Tavakoli  Victor Ntegeka  Patrick Willems  Florimond De Smedt  Okke Batelaan 《水文研究》2013,27(25):3649-3662

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Seismic expression and inferred depositional environments of Plio-Pleistocene sedimentary sequences in the southwestern Caspian Sea   总被引：1，自引：1，他引：0  

Mohsen?Kalani  Saeed?KhodabakhshEmail author  Changiz?Amirbehboudi 《Geo-Marine Letters》2008,28(1):31-41

Eight seismic profiles from the southwestern Caspian Sea were analyzed to establish the sedimentary environments and depositional history in the South Caspian Basin since Pliocene times. Based on reflection terminations, nine sequence boundaries (S1 to S9) were identified and traced across the study area. Consequently, nine depositional sequences (S1–S9) were defined on the basis of seismic facies analysis. The results suggest a transition from non-marine sedimentation in the Lower Pliocene to marine-dominated conditions in the Upper Pliocene (S1–S4). Marine conditions then continued to the present time; however, several sea-level changes led to the formation of sequences S5 to S9. Although no local sea-level curve is available due to a lack of well data, there is good agreement between the seismic stratigraphy of the study area and a published regional sea-level curve.  相似文献   

Metal pollution assessment and multivariate analysis in sediment of Anzali international wetland   总被引：4，自引：1，他引：3  

Ahmad Jamshidi-Zanjani  Mohsen Saeedi 《Environmental Earth Sciences》2013,70(4):1791-1808

Anzali international wetland located in southwestern Caspian Sea coast is one of the most important wetlands of Iran from environmental and ecological points of view. Metal concentrations (Cu, Zn, Cr, Fe, Mn, Pb, Ni, Cd, and Li) in 41 surface sediment samples from Anzali wetland were determined. Assessment of ecological risk of sediment samples as well as their degree of contamination revealed considerable ecological risk and moderate degree of contamination in eastern part of the study area. Multivariate statistical analyses were used to identify metal content relationship and their origin. Higher enrichment factors of Cd, Pb, and Zn exhibited probable effects on human activities. Based on sediment quality guidelines (SQGs), moderate potential toxicity levels of sediment samples were identified. A new sediment quality index named sediment toxicity degree was developed based on the results of the multivariate statistical analysis to assess metal toxicity in surface sediments of aquatic systems. Results showed higher sensitivity of the new index (ST_d) to assess toxic effect of heavy metals on sediments and better capability to differentiate zones with different levels of risk within the study area than that of some other indices such as SQG-Q.  相似文献   

Study of a Neogene basin dynamics: The “Bizerte basin”, northeastern Tunisia: relevance to the global Messinian Salinity Crisis     

Salah Harrab  Beya Mannai-Tayech  Mohsen Rabhi  Fouad Zargouni 《Comptes Rendus Geoscience》2013,345(5-6):251-261

The Messinian sediments of northeastern Tunisia were deposited under an active tectonic setting. They are organized in sequences indicating a transitional deposit from margin – littoral to lacustrine – continental facies. These series unconformably overlie the Serravallian–Tortonian silty clays packages, and are overlain by the transgressive Early Pliocene marl (Zanclean). The presence of evaporitic strata points out to the Messinian Salinity Crisis described in the peripheral basins of the western Mediterranean. The Messinian sedimentation was found to have been closely controlled by transtensive tectonics and differential subsidence at a large spatio-temporal scale. It is organized in sequences typical of a depositional environment controlled by eustatism, tectonic and maybe by climate changes. Despite the existence of some local specific sedimentological characteristics, our results corroborate previous findings that pointed out to the Messinian times as a singular period all around the Mediterranean Basin. Field and subsurface seismic profile data helped reconstructing either the sedimentary or tectonic unconformities existing between the studied Messinian series and older Neogene successions.  相似文献   

Matter infall in collapsing molecular cloud cores with an axial magnetic field     

Mohsen Nejad-Asghar 《Astrophysics and Space Science》2011,334(1):27-33

The magnetic fields affect collapse of molecular cloud cores. Here, we consider a collapsing core with an axial magnetic field and investigate its effect on infall of matter and formation of accretion disk. For this purpose, the equations of motion of ions and neutral infalling particles are numerically solved to obtain the streamlines of trajectories. The results show that in a non-steady state of ionization and ion–neutral coupling, which is not unexpected in the case of infall, the radius of accretion disk will be larger as a consequence of axial magnetic field.  相似文献   

Quality assessment for terrestrial gravity anomalies by variance component estimation using GOCE gradiometric data and Earth’s gravity models     

Mehdi Eshagh  Mohsen Romeshkani 《Studia Geophysica et Geodaetica》2013,57(1):67-83

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Incremental dynamic analysis of concrete gravity dams including base and lift joints     

Mohammad Alembagheri  Mohsen Ghaemian 《地震工程与工程振动(英文版)》2013,12(1):119-134

The growth in computer processing power has made it possible to use time-consuming analysis methods such as incremental dynamic analysis(IDA) with higher accuracy in less time.In an IDA study,a series of earthquake records are applied to a structure at successively increasing intensity levels,which causes the structure to shift from the elastic state into the inelastic state and finally into collapse.In this way,the limit-states and capacity of a structure can be determined.In the present research,the IDA of a concrete gravity dam considering a nonlinear concrete behavior,and sliding planes within the dam body and at the dam-foundation interface,is performed.The influence of the friction angle and lift joint slope on the response parameters are investigated and the various limit-states of the dam are recognized.It is observed that by introducing a lift joint,the tensile damage can be avoided for the dam structure.The lift joint sliding is essentially independent of the base joint friction angle and the upper ligament over the inclined lift joint slides into the upstream direction in strong earthquakes.  相似文献   

Rayleigh–Taylor instability in an ionized medium     

Mohsen Shadmehri  Asiyeh Yaghoobi  Mahdi Khajavi 《Astrophysics and Space Science》2013,347(1):151-157

We study the linear theory of the magnetized Rayleigh–Taylor instability in a system consisting of ions and neutrals. Both components are affected by a uniform vertical gravitational field. We consider ions and neutrals as two separate fluid systems that can exchange momentum through collisions. However, ions have a direct interaction with the magnetic field lines but neutrals are not affected by the field directly. The equations of our two-fluid model are linearized and by applying a set of proper boundary conditions, a general dispersion relation is derived for our two superposed fluids separated by a horizontal boundary. We found two unstable modes for a range of wavenumbers. It seems that one of the unstable modes corresponds to the ions and the other one is for the neutrals. Both modes are reduced with increasing particle collision rate and ionization fraction. We show that if the two-fluid nature is considered, the RT instability would not be suppressed and we also show that the growth time of the perturbations increases. As an example, we apply our analysis to the Local Clouds which seem to have arisen because of the RT instability. Assuming that the clouds are partially ionized, we find that the growth rate of these clouds increases in comparison to the fully ionized case.  相似文献   

Distribution Coefficient of Trichloroethylene in Soil-Water Systems     

Mohsen Mehran  Roger L. Olsen  Bryan M. Rector 《Ground water》1987,25(3):275-282

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Modeling and Prediction of Habitat Suitability for Ferula gummosa Medicinal Plant in a Mountainous Area     

Mohammady  Majid  Pourghasemi  Hamid Reza  Yousefi  Saleh  Dastres  Emran  Edalat  Mohsen  Pouyan  Soheila  Eskandari  Saeedeh 《Natural Resources Research》2021,30(6):4861-4884

Natural Resources Research - Habitat suitability modeling and mapping are important aspects of long-term strategies for sustaining plant ecosystems. In this study, seven state-of-the-art machine...  相似文献