Sharif Digital Repository

The most important step in current dynamic analysis of machine foundations is determining dynamic impedance functions. Impedance functions are defined as ratios of applied force or moment to induced displacement or rotation angle of foundation. In this research, horizontal dynamic response of foundation on homogeneous halfspace was investigated using physical modeling. Soil medium was built in a 1mx1mx0.8m steel box whose interior walls were covered by 0.1m of sawdust (a material with high damping). In order to prevent possible reflection of waves, this cover was extended to the box bottom with 0.2 m thickness. Sand raining method was used to build soil medium. In this method, with... 

A considerable number of engineering applications deal with flow of fluid(s) through particulate porous media. For certain engineering problems, fluid flow may displace and even dislodge the solid particles from the mass where a fluid-particle flow occurs. The complexity of involving processes which should be studied at the scale of moving particles transforms the analyses of these problems towards a difficult engineering task. Characteristics of solid grains such as size and shape and properties of the flowing fluid(s) such as viscosity and surface tension play essential roles in the behavior of fluid-particle systems. Also, when fluid flows through porous media, secondary processes such as... 

With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system.... 

Polymer concrete is well-known for the quick repair of concrete structures and pavement. Many concrete structures such as bridges, offshore, and pavements are under cyclic loads when they are exposed to different environmental conditions during their lifespan. However, there are relatively few studies on the durability of Polymer concrete. The durability and fatigue performance of these structures are significant issues that should be considered. This study aims to investigate the long-term environmental effects on the mechanical properties of Polymer concrete. Therefore, polymer and ordinary cement concrete specimens were prepared and exposed to four chemical solutions with pH values of...