Sharif Digital Repository

This study investigated the effects of magnetic field on pressure drop and heat transfer enhancement of nanofluid in a pipe containing porous medium by a 2D simulation. The study involves modeling the flow of nanofluid as a single-phase flow and simulating fluid flow through the porous medium using the Darcy–Brinkman–Forchheimer equation. A constant uniform heat flux around the pipe is used as the thermal boundary condition. The simulations evaluate the effect of several parameters, such as Reynolds number, porosity, thermal conductivity of the porous medium, and nanofluid material. The findings show that utilizing a magnetic field increases heat transfer in nanofluid. Based on the... 

Interventions such as seismic retrofits and reconstruction of vulnerable buildings can minimize the social and economic consequences of future earthquakes. Various policies can reduce the vulnerability of communities in the face of future earthquakes by enhancing the public risk perception and reducing the costs of interventions for the landlords. There is a need for appropriate tools that can characterize the dynamics of the housing market in response to these policies. The simulation model presented in this manuscript addresses this need. In this model, the decision of the tenants and landlords is characterized by utilizing prospect theory. The impact of candidate policy interventions on... 

Earthquakes can cause significant damage to vulnerable residential buildings and cause irreversible adverse economic, social, and socioeconomic consequences. Implementing hazard mitigation policies can enhance homeowners' willingness to adopt hazard mitigation measures such as seismic retrofits or insurance. Several past studies have proposed models that aimed to explain individuals' hazard mitigation behavior. Despite their advantages, these decision-making models are subject to limitations. This manuscript proposes a new decision-making model that addresses the shortcomings of previous models. The proposed decision-making model is then incorporated at the core of an agent-based model to... 

One of the methods that is used nowadays in enhanced oil recovery is surfactant flooding. The main mechanisms of surfactant flooding in reservoir consist of reduction of interfacial tension between water and oil and modification of rock wettability. In this study, the authors simulate the surfactant injection process in Darcy scale and in one-dimensional, multicomponent, multiphase state, and effects of physical phenomena such as adsorption, dispersion, convection, and exchange between fluids and solids are considered. Wettability alteration of reservoir rock due to presence of surfactant in injected fluid is detected in relative permeability and capillary pressure curves. First, the authors... 

Building owners’ appropriate risk-mitigation decisions can minimize the social, economic, and socioeconomic consequences of earthquakes. Implementation of appropriate policies can increase the adoption of seismic retrofit measures through the modification of owners’ beliefs. Social interactions among owners can influence their response to the implemented policies. There is a need for appropriate tools that consider the social interactions among the owners and facilitate the evaluation of their response to seismic retrofit promotion policies. The agent-based simulation model in this manuscript addresses this need. The implementation of policies and interactions among agents can influence... 

Building owners’ appropriate risk-mitigation decisions can minimize the social, economic, and socioeconomic consequences of earthquakes. Implementation of appropriate policies can increase the adoption of seismic retrofit measures through the modification of owners’ beliefs. Social interactions among owners can influence their response to the implemented policies. There is a need for appropriate tools that consider the social interactions among the owners and facilitate the evaluation of their response to seismic retrofit promotion policies. The agent-based simulation model in this manuscript addresses this need. The implementation of policies and interactions among agents can influence... 

The authors simulated a reservoir by using two-layer perceptron. Indeed a model was developed to simulate the increase in oil recovery caused by bacteria injection into an oil reservoir. This model was affected by reservoir temperature and amount of water injected into the reservoir for enhancing oil recovery. Comparing experimental and simulation results and also the erratic trend of data show that the neural networks have modeled this system properly. Considering the effects of nonlinear factors and their erratic and unknown impacts on recovered oil, the perceptron neural network can develop a proper model for oil recovery factor in various conditions. The neural networks have not been... 

This paper concerns on experimental investigation of biopolymer/polymer flooding in fractured five-spot systems. In this study, a series of polymer injection processes were performed on five-spot glass type micromodels saturated with heavy crude oil. Seven fractured glass type micromodels were used to illustrate the effects of polymer type/concentration on oil recovery efficiency in presence of fractures with different geometrical properties (i.e., fractures orientation, length and number of fractures). Four synthetic polymers as well as a biopolymer at different levels of concentration were tested. Also a micromodel constituted from dead-end pores with various geometrical properties was... 

In the absence of effective and adequate vaccines, healthcare decision-makers must rely on non-pharmaceutical interventions (NPIs), such as lockdown, testing, hospital capacity building, and increasing the number of medical staff to control the outbreak of an infectious disease like COVID-19. This manuscript presents a System Dynamics (SD) model to analyze the healthcare system performance under various NPIs during a pandemic. The proposed model, which extends the commonly-used Susceptible-Exposed-Infectious-Recovered (SEIR) model, comprises four sub-models: outbreak, hospital performance, medicine supply, and staff functionality. These sub-models work in harmony to stimulate the impact of... 

Recommender Systems have become an attractive field within the recent decade because they facilitate users' selection process within limited time. Conventional recommender systems have proposed numerous methods focusing on recommendations to individual users. Recently, due to a significant increase in the number of users, studies in this field have shifted to properly identify groups of people with similar preferences and provide a list of recommendations for each group. Offering a recommendations list to each individual requires significant computational cost and it is therefore often not efficient. So far, most of the studies impose four restrictive assumptions: (1) limited number of... 

In this paper, we consider a dual-sourcing model with constant demand and stochastic lead times. Two suppliers may be different in terms of purchasing prices and lead-time parameters. The ordering takes place when the inventory level depletes to a reorder level, and the order is split among two suppliers. Unlike previous works in the order splitting literature, the supply lead time between vendor and buyer as well as unit purchasing prices is considered to be order quantity dependent. The proposed model finds out the optimal reorder point, order quantity and splitting proportion, using a solution procedure. Numerical results show that neglecting the relationship between ordering batch size...