Sharif Digital Repository

One of the most important elements of performance-based seismic engineering elements is precision in determination of seismic displacement demand evaluation. Although seismic demands which are estimated by utilizing non-linear dynamic analysis are most effective, but with regards to inherent complexities of these methods and demands for time-consuming calculations , non-¬linear static methods seems to be an appropriate representative and is recently considered by engineers. In countries with oil resources including Iran, offshore jacket platforms are among outstanding structures being considered. Inasmuch as high design and execution expenses of these structures and also important role of... 

The extensive use of nonlinear loads such as motor drives and new generation of home appliances has caused a deterioration of power quality in power systems. The use of active power filters due to the fast variation of the loads has been recommended by power engineering. In this method, the harmonic profiles are controlled by applying active filters in a distribution feeder. Optimal placement of active filters in a distribution system due to the increase of harmonic generation loads has attracted researchers. However placement of each filter is the major concern that researchers face. In this paper, a new objective function is introduced to determine the optimal number and location of active... 

Formation damage in oil and gas wells is mainly induced by drilling operations. Filtrate and particle invasion into formation as the sources of this damage caused serious problems, e.g. reduction of production rates. Therefore numerical modeling of this phenomenon helps us to better understand the process, and as a result, control and reduce formation damage associated with this impairment. In this research, a model to estimate the invasion depth and damage of mud filtrate from water-based mud is presented. Filtrate invasion into the formation is investigated by convection-diffusion equation with regard to dispersion term. The invasion depth is obtained from mud filtrate profile in the... 

This study highlights an important distinction between heat transfer mechanism in dry and saturated soil. Soil temperature data recorded during model tests, soil thermal response predicted using finite difference and analytical methods are compared with finite element models. In recent years, due to the industrial development of human societies, the energy consumption has been increased worldwide. On the other hand, the most commonly used energy resources are non-renewable energies. Therefore, governments and industries aimed to develop a technology which provides economical use of renewable energy sources. One of the renewable energy sources is the geothermal energy of the Earth. In this... 

In the real engineering problems, the existing materials in the nature or human-made materials, contain different heterogeneities from the view of small scale. Reinforced composite materials and porous media containing grains or micro-cracks are some examples of these materials. Due to the large amount of these heterogeneities as well as the small size, direct modelling of these micro-structures requires extremely high computational and memorial cost. Also, the equivalent models introduced in the literature, have strong limitations and therefore, cannot capture accurate behavior of the material. Hence, multiscale methods have been proposed in order to model these heterogeneous media with... 

Shallow geothermal energy is a renewable and sustainable form of energy that has the potential to help alleviate the growing climate and energy crisis. The most common system used to extract shallow geothermal energy is the ground source heat pump (GSHP) system. The concept of using underground structures in exploiting shallow geothermal energy for space heating and cooling has received increasing attention. This study focuses on the use of geothermal tunnels as a means of extracting shallow geothermal energy.This research examines the effects of different heat transfer mechanisms, and highlights the effects of this phenomenon by focusing on the effects of natural convection around the...