Analysis of star camera errors in GRACE data and their impact on monthly gravity field models   总被引：1，自引：1，他引：0  

Pedro Inácio  Pavel Ditmar  Roland Klees  Hassan Hashemi Farahani 《Journal of Geodesy》2015,89(6):551-571

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Frictionless contact formulation for dynamic analysis of nonlinear saturated porous media based on the mortar method          下载免费PDF全文

Hassan Sabetamal  Majid Nazem  Scott W. Sloan  John P. Carter 《国际地质力学数值与分析法杂志》2016,40(1):25-61

A finite element algorithm for frictionless contact problems in a two‐phase saturated porous medium, considering finite deformation and inertia effects, has been formulated and implemented in a finite element programme. The mechanical behaviour of the saturated porous medium is predicted using mixture theory, which models the dynamic advection of fluids through a fully saturated porous solid matrix. The resulting mixed formulation predicts all field variables including the solid displacement, pore fluid pressure and Darcy velocity of the pore fluid. The contact constraints arising from the requirement for continuity of the contact traction, as well as the fluid flow across the contact interface, are enforced using a penalty approach that is regularised with an augmented Lagrangian method. The contact formulation is based on a mortar segment‐to‐segment scheme that allows the interpolation functions of the contact elements to be of order N. The main thrust of this paper is therefore how to deal with contact interfaces in problems that involve both dynamics and consolidation and possibly large deformations of porous media. The numerical algorithm is first verified using several illustrative examples. This algorithm is then employed to solve a pipe‐seabed interaction problem, involving large deformations and dynamic effects, and the results of the analysis are also compared with those obtained using a node‐to‐segment contact algorithm. The results of this study indicate that the proposed method is able to solve the highly nonlinear problem of dynamic soil–structure interaction when coupled with pore water pressures and Darcy velocity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Steel rings as seismic fuses for enhancing ductility of cross braced frames     

Behnamfar  Farhad  Arman  Saeid  Zibasokhan  Hassan 《地震工程与工程振动(英文版)》2022,21(4):1103-1117

A new remedy is proposed in this study to increase the ductility of cross-braced frames to a level comparable with ductile moment frames. The suggested system consists of one or two concentric steel rings installed in the cross-braced bay vertically. The steel rings are designed such that they fail in bending sooner than failure of the braces in compression. Then the rings act as seismic fuses with multiple bending plastic hinges. Using nonlinear static analysis, it is shown that the proposed system can be designed to behave like cross-braced frames with regard to stiffness and strength, and like special moment frames with regard to ductility. Seismic design factors for the proposed system are recommended based on nonlinear pushover and cyclic analysis studies.

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Introduction of sealing fault in Asmari reservoir by using FMI and RFT in one of the Iranian naturally fractured oil fields     

Zohreh Movahed  Radzuan Junin  Hassan Amiri Bakhtiari  Zeynalabedin Safarkhanlou  Ali Asghar Movahed  Mostafa Alizadeh 《Arabian Journal of Geosciences》2015,8(12):10919-10936

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Syn-rift unconformities punctuating the lower–middle Cambrian transition in the Atlas Rift,Morocco     

J. Javier Álvaro  Hassan Ezzouhairi  Sébastien Clausen  M. Luisa Ribeiro  Rita Solá 《International Journal of Earth Sciences》2015,104(3):753-773

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Hydrodynamic Efficiency Improvement of the High Skew Propeller for the Underwater Vehicle Under Surface and Submerged Conditions     

Hassan Ghassemi  Parviz Ghadimi 《青岛海洋大学学报(英文版)》2011,(4):314-324

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http://www.sciencedirect.com/science/article/pii/S167498711100048X     

Ibrahim H. Khalif  Mohammed Z. El-Bialy  Doa’a M. Hassan 《地学前缘(英文版)》2011,2(3):385-402

Metavolcanic rocks hosting base metal sulphide mineralization, and belonging to the Kid Metamorphic Complex, are exposed in the Samra-Tarr area, Southern Sinai. The rocks consist of slightly metamorphosed varicolored porphyritic lavas of rhyolite-to-andesite composition, and their equivalent pyroclastics. Geochemically, these metavolcanics are classified as high-K calc-alkaline, metaluminous andesites, trachyandesites, dacites, and rhyolites. The geochemical characteristics of these metavolcanics strongly point to their derivation from continental crust in an active continental margin. The sulphide mineralization in these metavolcanics occurs in two major ore zones, and is represented by four distinct styles of mineralization. The mineralization occurs either as low-grade disseminations or as small massive pockets. The associated hydrothermal alterations include carbonatization, silicification, sericitization and argillic alterations. The base metal sulphide mineralization is epigenetic and was formed by hydrothermal solutions associated with subduction-related volcanic activity.  相似文献   

Flash flood risk estimation along the St. Katherine road,southern Sinai,Egypt using GIS based morphometry and satellite imagery   总被引：7，自引：4，他引：3  

Ahmed M. Youssef  Biswajeet Pradhan  Abdallah Mohamed Hassan 《Environmental Earth Sciences》2011,62(3):611-623

Flash floods are considered to be one of the worst weather-related natural disasters. They are dangerous because they are sudden and are highly unpredictable following brief spells of heavy rain. Several qualitative methods exist in the literature for the estimations of the risk level of flash flood hazard within a watershed. This paper presents the utilization of remote sensing data such as enhanced Thematic Mapper Plus (ETM+), Shuttle Radar Topography Mission (SRTM), coupled with geological, geomorphological, and field data in a GIS environment for the estimation of the flash flood risk along the Feiran–Katherine road, southern Sinai, Egypt. This road is a vital corridor for the tourists visiting here for religious purposes (St. Katherine monastery) and is subjected to frequent flash floods, causing heavy damage to man-made features. In this paper, morphometric analyses have been used to estimate the flash flood risk levels of sub-watersheds within the Wadi Feiran basin. First, drainage characteristics are captured by a set of parameters relevant to the flash flood risk. Further, comparison between the effectiveness of the sub-basins has been performed in order to understand the active ones. A detailed geomorphological map for the most hazardous sub-basins is presented. In addition, a map identifying sensitive sections is constructed for the Feiran–Katherine road. Finally, the most influenced factors for both flash flood hazard and critical sensitive zones have been discussed. The results of this study can initiate appropriate measures to mitigate the probable hazards in the area.  相似文献   

Mineralogical, geochemical, and geotechnical evaluation of Al-Sowera soil for the building brick industry in Iraq     

Salih Muhammad Awadh  Hamed Hassan Abdullah 《Arabian Journal of Geosciences》2011,4(3-4):413-419

The raw material soil of Al-Sowera factory quarry (quarry soil and mixture) used for building brick industry was tested mineralogically, geochemically and geotechnically. Mineral components of soil are characterized by Clay minerals (Palygoriskite and chlorite) and non-clay minerals like calcite, quratz, feldspar, gypsum and halite. The raw material is deficient in SiO₂, Al₂O₃, K₂O, Fe₂O₃ and MgO, while enriched in CaO. Loss on ignition and Na₂O are in suitable level and appear to be concordant with the standard. Grain size analyses show that the decreasing sand and clay, and increasing silt ratio in both quarry soil and mixture caused decreasing in strength of brick during molding and after firing. The quarry soil is characterized by high plasticity clayey soil of 30.49 plastic index (P.I), whereas the mixture considered a clayey soil has a low plasticity of 7.7 plastic index (P.I). To improve the chemical and physical properties of the raw material, alumina-silicate minerals rich in K₂O, Fe₂O₃ and MgO are recommended as additive materials to the main mixture.  相似文献   

Hydrodynamic efficiency improvement of the High Skew Propeller for the underwater vehicle under surface and submerged conditions     

Hassan Ghassemi  Parviz Ghadimi 《中国海洋大学学报(英文版)》2011,10(4):314-324

An algorithm based on the Boundary Element Method(BEM)is presented for designing the High Skew Propeller(HSP)used in an Underwater Vehicle(UV).Since UVs operate under two different kinds of working conditions(i.e.surface and submerged conditions),the design of such a propeller is an unwieldy task.This is mainly due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different.Therefore,some factors are necessary for the design of the opti-mum propeller to utilize the power under the mentioned conditions.The design objectives of the optimum propeller are to obtain the highest possible thrust and efficiency with the minimum torque.For the current UV,the main dimensions of the propeller are pre-dicted based on the given required thrust and the defined operating conditions.These dimensions(number of blades,pitch,diameter,expanded area ratio,thickness and camber)are determined through iterative procedure.Because the propeller operates at the stern of the UV where the inflow velocity to the propeller is non-uniform,a 5-blade HSP is preferred for running the UV.Finally,the propel-ler is designed based on the numerical calculations to acquire the improved hydrodynamic efficiency.  相似文献