Sharif Digital Repository

The wireless sensor networks include a lot of sensor nodes with a limited energy distributed in a limited geography area. One of the important issues in these networks is the increased longevity of a network. In a wireless sensor network a long connecting distance between sensors and sink uses a lot of energy and decreases the longevity of network. Since clustering can decrease requirement of using energy for wireless sensor networks, we are following an intelligent technique for forming and managing clusters in this article. With clustering wireless sensor network and using a genetic algorithms we can decrease the connecting distance a little, so the longevity of network will be more. The... 

Conic shell structures are widely used in aerospace industries. In the literature various models have been proposed to failure analysis of composite materials. Clearly, each model has a favorable range of applications. In this paper tensile, compressive, shear and thermal expansion properties of tape-wounded Carbon/Phenolic composites are firstly measured at various temperatures in range 23–200°C. The captured properties are then taken into account to progressive failure analysis of a conic Carbon/Phenolic structure under internal pressure and thermal loadings. For this end, a particular failure criterion is proposed to predict failure in the composite structures with a reasonable margin of... 

In the present research work the 2024 aluminum alloy was reinforced with SiC particles via powder metallurgy method. The effect of heat treatment conditions on artificial aging kinetics was investigated. The solution treatment of the composite sample and the unreinforced alloy was carried out at 495 °C for 1, 2 and 3 h followed by aging at 191 °C for various aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the alloy. The peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 and 3 h, but took place at longer times for the samples solution treated for 1 h.... 

Hydrogen generation from renewable energy resources is considered as a suitable solution to solve the problems related to the energy sector and the reduction of greenhouse gases. The aim of this study is to provide an integrated framework for identifying suitable areas for the construction of wind farms to produce hydrogen. For this purpose, a combined method of Geographic Information System (GIS) and multi-criteria decision making (MCDM) has been used to locate the power plant in Yazd province. The GIS method in the present study consisted of two parts: constraints and criteria. The constraint section included areas that were unsuitable for the construction of wind farms to produce power...