Sharif Digital Repository

Design of thick-walled spherical and cylindrical vessels as fluids containers of high gradient thermal loading is a challenging issue. Using these tanks in high pressure and temperature gradient, particularly in chemical industries, needs to use new methods in design. Elasto-Plastic solution for thick-walled hollow spherical and cylindrical tanks made of FG materials subjected to internal pressure and temperature loading is presented. The power law modeling is used for through-the-thickness variation of mechanical properties. This method is using the new advanced materials with high pressure and thermal strength in fabricating these vessels. One of these materials is functionally graded (FG)... 

This thesis considers theoretical, analytical and engineering design issues relating to non-orthogonal Spectrally Efficient Frequency Division Multiplexing (SEFDM) communication systems that exhibit significant spectral merits when compared to Orthogonal FDM (OFDM) schemes. Alas, the practical implementation of such systems raises significant challenges, with the receivers being the bottleneck.
This research explores detection of SEFDM signals. The mathematical foundations of such signals lead to proposals of different orthonormalisation techniques as required at the receivers of non-orthogonal FDM systems. To address SEFDM detection, two approaches are considered: either attempt to... 

This research presents scheduling of several different projects in supply chain environment which activities of these projects are performed by some contractor companies. A new practical model for solving project scheduling problem in supply chain environment is present. Multi renewable resource presents in the model of research. The research proves that the model is NP-Hard. A genetic algorithm and a simulated annealing algorithm are proposed for solving the model. The parameters of genetic algorithm such as the number of steps, the number of mutation in each step, the number of crossover in each step, the number of generation phase and also the parameters of simulated annealing algorithm... 

Circular polarization (CP) is one of the common polarization types used in wireless systems for frequency identification (RFID), global positioning (GPS) and wireless local area networks (WLAN), since it can provide greater flexibility in orientation angle between transmitter and receiver, and better mobility and weather penetration than the linearly polarized antennas. Magnetic permeability in ferrites can be tuned by external magnetic field ; So ferrites can be good candidates for new reconfigurable CP antenna technology. In this project, we will consider circularly polarized slot antenna with a wide axial ratio beamwidth that consists of a normally magnetized ferrite substrate mounted... 

In urban rail transport systems such as subway, Trains are constantly accelerate and brake, so the braking system is of great importance in energy consumption and constitute about 30 to 40 percent of total energy consumption trains, thus retrieval braking energy will lead to significant savings in urban rail transport systems. In this paper, in the beginning, different storage equipments for storage braking energy have been studied and compared and finally Supercapacitors due to technical and economic features have been selected for the storge of equipment. These systems can be implemented in both stationary and onboard. For precise evaluation and select the appropriate storage system, by... 

Now a days, the ability of measuring the mechanical properties of the living cells in in experiments has been increased. Experiments shows that the stem cells could alter their faith in different mechanical situations, but an integrated model about this phenomenon in literature has not been introduced yet. In this research thesis s minimal cell model (MMC) is developed to capture the behavior of the cells on substrates with varying mechanical properties and morphologies, MMC consists of large scale models for outer membrane of the cell and nuclear envelope, cytoplasmic area, chromatin fibers and Extra cellular matrix. Each component of the MMC will be placed in an integrated software to... 

Motion simulators have been highly sought after by the growth of the aerospace industry. In the meantime, the Stewart mechanism, or the so-called Hexapads, is a robot that, in addition to being used in machining tools, is mainly used to simulate the flight. The robot is considering the project to test parts and equipment installed in marine vessels under sea movements and waves. Therefore, according to information obtained through real case studies, the purpose of this project is to design and implement a hexapad controller and user interface for samples weighing up to 2 tons which can handle linear accelerations up to 1 g, rotary accelerations up to 200 º / s2 performs at a frequency... 

Due to the expanding trend of using induction furnaces in Iran, the production of sponge iron at a smaller scale by Midrex method has become important. Since induction furnaces cannot benefit from the oxygen blower and foam slag like arc furnaces, the induction furnace charge should be of a higher quality. In addition, as the oxidation conditions in induction furnace are higher in comparison to arc furnaces, re-oxidation control of the induction furnace is essential. Making briquettes is one of the processes, which reduces re-oxidation during melting and since the briquette remains floated on the melt until complete melting, the lower level of briquette's contact with ambient atmosphere and... 

In this article we have investigated an inventory control model with uncertainly in supply and capacity constraints in the volume and variety of goods for supply chain of chain toy stores. The purpose of model is to minimize inventory costs, ordering cost and the cost of shortage to develop an acceptable customer service level. In order to execute replenishment process of goods we propose three periodic review inventory control policies that are implemented automatic, step by step and by using indicators defined in this article. The major difference between the proposed policies and the as-is policy is to use categorization od goods based on specific characteristics. Each of the three...