Sharif Digital Repository

In this paper, a combined model of auto-transit assignment is introduced based on two complementarity formulations in the literature. The model accounts for interactions between the auto and transit modes through non-separable asymmetric demand and cost functions. A path-based solution algorithm is presented based on the three ideas of decomposition, column generation, and linearization, which have proved to be effective in tackling large-size networks. Numerical results over the Chicago sketch network suggest that the algorithm converges quickly within the first iterations, but is less effective as the solution gets closer to the neighborhood of the equilibrium solution. The sluggish... 

A system protection scheme is proposed to mitigate cascaded voltage collapses. Based on the post-contingency conditions of either existence or non-existence of an equilibrium solution, and with regard to the stability and security criteria, the proposed scheme finds the optimal set of remedies. The proposed stabilising scheme brings the non-equilibrium post-contingency operating point back inside a stable region, and then passes this point to the securing scheme. Also, to enhance the performance of the stabilising scheme, a sensitivity analysis method is presented to detect the most effective remedies. The proposed securing scheme converts the stable, but insecure operating point, to a... 

A thermodynamically consistent phase field theory for fracture is developed. An alternative approach to describe the reduction in the slope of the stress–strain curve and the reduction of the stresses to zero during damage is utilized by introducing transformation strain instead of the degradation function. The main requirements for the thermodynamic potential are presented and used to present the general energy terms. The analysis of the equilibrium solution is formulated which describes the desired stress–strain curves and for which the infinitesimal damage produces an infinitesimal change in the equilibrium elastic modulus. Analytical analysis of the equations is performed to calibrate... 

The wetting condition of the reservoir rock is the key to the success of any EOR technique and the ultimate oil recovery. Wettability is dictated by the surface chemistry related to the interactions between the fluids and the rock surface which determines the stability of the water film between the rock and the oil phase. Streaming potential measurement is one of the electrokinetic techniques used to determine the average zeta potential of porous rock which can provide reliable information on fluid-rock interaction and wettability state of the rock surface. Streaming potential measurement has recently been introduced in the oil reservoirs applications and there are still significant... 

The high reactivity of the carbonate rocks at various pH makes it difficult to evaluate the wettability, hence to find the recovery mechanisms behind modified waterflood in carbonate reservoirs. More recently, the streaming potential measurement is introduced as a method of electrokinetic phenomena more relevant to the subsurface systems. Regarding few experimental studies and in order to improve our understanding on streaming potential measurement, the electrokinetic studies on quartz and calcite surface were conducted as a function of pH in the range of 1.5–11.5 using an in-house novel setup of streaming potential measurement. High sensitivity of streaming potential coupling coefficient to...