Sharif Digital Repository

This study examines the behaviour of credit rating agencies during the credit crunch and compares it with normal economic conditions. The rating agencies claim that when assessing the credibility of firms over time, they can distinguish between short-term and long-term factors of credit shocks. To evaluate this claim, using Moody's rating data and variables that represent the macroeconomic conditions and financial and business risks, we study whether there is a difference in the tendency of rating agencies to downgrade the rating of firms in the periods of the credit crunch. A credit crunch index is used to determine the occurrence of credit cycles, which is obtained from the time series of... 

The daily increase of fuel prices, decrease of fuel resources and the need for controlling environmental pollution, reflect the importance of optimizing the heat recovery in different industries. In the past 20 years, Pinch technology has been considered as a powerful tool used for, recovering wasted energies, optimizing the energy transfer between hot and cold streams and reducing the need for additional services. In this thesis, Pinch technology is used to optimize the process of wafer and chocolate production in one of the KitKat’s factories and different retrofits for the increase of the heat recovery are proposed. urthermore, the data collected at this factory is used to investigate the... 

The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have... 

Out of several ground improvement techniques available, stone columns have been widely used. This technique has been successfully applied to increase the bearing capacity and to reduce the settlement for foundation of structures like liquid storage tanks, earthen embankments, raft foundations, etc., where a relatively large settlement is permissible. This technique has, generally, been proven successful in increasing the stiffness of weak soils, upgrading their safe bearing capacity, and reducing their total and differential settlements, as well as speeding up their consolidation process. The beneficial effects of stone column installation in weak deposits is manifested in the form of... 

Laminar forced convection flow through a channel partially filled with a porous material was numerically studied in this thesis. The Navier-Stokes and Brinkman-Forchheimer equations were used to model the fluid flow in the free and porous regions, respectively. Coupling of the pressure and velocity fields was resolved using the SIMPLEC algorithm. The local thermal equilibrium was adopted in the energy equation. The effects of the thermal conductivity ratio, Darcy number, porosity, Reynolds number and height of the porous insert on velocity and temperature field were investigated. The results show that the flow behavior and its associated heat transfer are susceptible to the variation of the...