1,720,987 research outputs found
Numerical study of the coupling effect between fluid diffusion and medium deformation for subsidence calculation over deep reservoirs
No full textApplication of the Virtual Internal Bond model for the simulation of delamination in laminated composites
No full textModelling of delamination growth in composite laminates by the virtual internal bond method
No full textThe paper examines the potential of the virtual internal bond (VIB) model to predict delamination initiation and growth in composite laminates. Finite elements implementing a formulation of the VIB model based on a two-parameter bond potential were used to simulate the resin-rich interface between adjacent layers. The performance of VIB elements was assessed by modelling the fracture response of unidirectional laminates with different cohesive strengths and fracture energy values in DCB, ENF and MMB tests. Even though some issues that restrict the applicability range of the model remain to be addressed, the good agreement achieved between finite element results and both analytical solutions and experimental results demonstrates the capability of VIB-based finite element models to correctly simulate the mechanics of delamination under different loading modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Seawater intrusion risk analysis under climate change conditions for the Gaza Strip aquifer (Palestine)
No full textSeawater intrusion (SWI) has become a major threat to coastal freshwater resources, particularly in the Mediterranean basin, where this problem is exacerbated by the lack of appropriate groundwater resources management and with serious potential impacts from projected climate changes. A proper analysis and risk assessment that includes climate scenarios is essential for the design of water management measures to mitigate the environmental and socio-economic impacts of SWI. In this study a methodology for SWI risk analysis in coastal aquifers is developed and applied to the Gaza Strip coastal aquifer in Palestine. The method is based on the origin-pathway-target model, evaluating the final value of SWI risk by applying the overlay principle to the hazard map (representing the origin of SWI), the vulnerability map (representing the pathway of groundwater flow) and the elements map (representing the target of SWI). Results indicate the important role of groundwater simulation in SWI risk assessment and illustrate how mitigation measures can be developed according to predefined criteria to arrive at quantifiable expected benefits
Finite element analysis of land subsidence above depleted reservoirs with pore pressure gradient and total stress formulations
No full textThe solution of the poroelastic equations for predicting land subsidence above productive gas/oil fields may be addressed by the principle of virtual works using either the effective intergranular stress, with the pore pressure gradient regarded as a distributed body force, or the total stress incorporating the pore pressure. In the finite element (FE) method both approaches prove equivalent at the global assembled level. However, at the element level apparently the equivalence does not hold, and the strength source related to the pore pressure seems to generate different local forces on the element nodes. The two formulations are briefly reviewed and discussed for triangular and tetrahedral finite elements. They are shown to yield different results at the global level as well in a three-dimensional axisymmetric porous medium if the FE integration is performed using the average element-wise radius. A modification to both formulations is suggested which allows to correctly solve the problem of a finite reservoir with an infinite pressure gradient, i.e. with a pore pressure discontinuity on its boundary
Integrazione GIS e software modellistica per l’analisi della vulnerabilità dell’acquifero della piana di Oristano (Sardegna)
No full textA Simulation/Optimization approach to manage groundwater resources in the Gaza aquifer (Palestinian Territories) under climate change conditions
No full textThe Gaza aquifer is the main source of water for agricultural, domestic, and industrial uses in the Gaza Strip. The
rapid increase on water demand due to continuous population growth has led to water scarcity and contamination
by seawater intrusion (SWI). Furthermore, current projections of future climatic conditions (IPCC, 2007) point to
potential decreases in available water, both inflows and outflows.
A numerical assessment of SWI in the Gaza coastal aquifer under climate induced changes has been carried out by
means of the CODESA-3D model of density-dependent variably saturated flow and salt transport in groundwaters.
After integrating available data on climatology, geology, geomorphology, hydrology, hydrogeology, soil use, and
groundwater exploitation relative to the period 1935-2010, the calibrated and validated model was used to simulate
the response of the hydrological basin to actual and future scenarios of climate change obtained from different
regional circulation models. The results clearly show that, if current pumping rates are maintained, seawater
intrusion will worsen.
To manage sustainable aquifer development under effective recharge operations and water quality constraints, a
decision support system based on a simulation/optimization (S/O) approach was applied to the Gaza study site.
The S/O approach is based on coupling the CODESA-3D model with the Carroll’s Genetic Algorithm Driver.
The optimization model incorporates two conflicting objectives using a penalty method: maximizing pumping
rates from the aquifer wells while limiting the salinity of the water withdrawn. The resulting coastal aquifer
management model was applied over a 30-year time period to identify the optimum spatial distribution of pumping
rates at the control wells. The optimized solution provides for a general increase in water table levels and a
decrease in the total extracted salt mass while keeping total abstraction rates relatively constant, with reference to
non-optimized conditions
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