Sharif Digital Repository

Road accidents are currently one the main existing problems and a big challenge in Iran that is putting the lives of Iranian citizens in danger. Each accident is the result of a complex interplay between road users, vehicles, roads and environment. One of the main goals of accident data analysis is to identify and determine the main factors of a road accident. The dataset used here was obtained from the road traffic police and is stored in 3 different databases and corresponds to the accidents that happened between years 1390 and 1395 according to the Shamsi calendar. In this thesis, in order to deal with the inherent complexity and heterogeneity of the accident data, we will first introduce... 

The present study aims at investigating the stability of flexible spinning cylinders conveying flow in an external fluid Medium. Using the linearized Navier-Stokes equations for the flow, a two-dimensional model is developed governing the fluid motion. The resultant force exerted on the flexible cylinder wall due to the fluid interactions is calculated as a function of the lateral acceleration. Applying the Hamilton principle, the governing equations of flexural vibration of the rotary flexible cylinder mounted on simply supported axles are derived. Having the forces due to the conveying fluid calculated and substituting into the governing equations, a coupled field governing equations of... 

Artemia (brine shrimp) is a genus of crustaceans that lives in saltwater and due to having unique features, in producing the food and nutrients needed for larvae and other types of farmed sea creatures, is of great importance. In its natural environment under certain conditions, Artemia produces cysts that float at the water surface and are driven ashore by wind and waves. These cysts are inactive and do not develop further as long as they are kept dry. Upon immersion in seawater, the biconcave cysts hydrate and become spherical and, within the shell, the embryo resumes its interrupted metabolism. After about 20 h the outer membrane of the cyst breaking and the embryo appears, surrounded by... 

In the present study, the nonlinear vibrations of the rotor on the nonlinear bearing have been studied by the multiple scale method. To achieve this goal, Jeffcott models, two degrees of freedom and rotating Euler-Bernoulli beam have been used as rotors and insulators and nonlinear tilting-bearing bearings have been used as supports.To better understand the importance of the supports in the analysis of rotating systems, the rotor joints with isolates with high static stiffness and low dynamic stiffness have been considered and the dynamic behavior of the system has been studied using the multiple scale method. The results of this study showed that this type of nonlinear isolator has a good... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key...