d. mokhtari

Due to its special political standing and geographical location, the land of Iran has always witnessed many natural and unnatural disasters throughout history. Therefore, the theoretical and practical position of passive defense in the face of crises is very important in this region. The location of military centers can play a significant role in passive defense naturally if it is done based on location studies and land management principles. This study is a practical research with descriptive-analytical and survey methods. In this study, in order to evaluate the factors affecting the location of military centers from the perspective of passive defense in the northwest region, the following restrictions have been used: climatic parameters (including the frequency of occurrence of frost, rain, snow, storm, dust and fog and also the wind speed), the geomorphologic and geologic parameters (the land slope and the land inclination direction , height and lithology), the parameters of accessibility of man-made centers (the distance from urban points and the distance from reservoir dams), infrastructure parameters (the distance from communication routes, the distance from airports and the distance from air corridors) and hydrological specifications (such as the distance from waterways). Then, using AHP analytical method, each of the studied parameters was given a numerical weight due to their importance in passive defense. To calculate the weight of indicators and the importance of the coefficient of each criterion, the process of hierarchical and software analysis of Expert Choice software was used. Finally, by modeling them in the GIS environment and also by using the overlap method, all effective layers in passive defense were combined. The results showed that very limited and scattered areas of the region under study, have the potential of housing military and civilian centers from the passive defense perspective.

In this research, the effect of several unconventional obstructions with cubic, spherical, cylindrical, and cone geometries on the propulsion vector of a convergent-divergent micro nozzle as a new method in propulsion vector control is experimentally investigated. For this purpose, a convergent-divergent nozzle was designed and constructed in small dimensions. This nozzle is such that the Mach number is its nominal output in full expansion conditions 2. The wall of this nozzle is designed to measure pressure variations with pressure holes. Also, in the nozzle wall, a duct has been created to apply a bulge inside the nozzle. Pressure sensors and the shadograph system have been used to pressure measurement and check the outlet flow field respectively. The total pressure of the calming chamber is constant in all experiments and is equal to 5.5 times. The results of this study show that the maximum deviation is related to an obstruction with a cubic geometry which is 2.1 degrees. Also, the geometries that have sharp corners are more shock-shaped and hit the opposite wall. In this research, the shock formed by a cubic barrier has hit the opposite wall, but with a spherical shaped and cone-shaped barrier, the shock comes out from the nozzle. Also, these results indicate that the axial force of the nozzle has been reduced to a very small extent.