Sharif Digital Repository

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have... 

In this thesis, experimental and numerical investigations are performed on dynamic behavior of fiber reinforced concrete (FRC) by split Hopkinson pressure bar (SHPB) and penetration tests. In the experimental part, effects of parameters such as quasi-static compressive strength of matrix (36 and 48 MPa), strain rate (3*10-5 up to 100 s-1), type of fibers (crimped steel, hooked-end steel, micro polypropylene and micro polypropylene) and volume fraction of the fibers (0%, 1% and 2%) are studied by employing SHPB apparatus on testing more than 150 specimens. Also, different types of FRC panels with 5 cm thickness were casted to perform 20 penetration tests with compressed gas gun apparatus. The... 

Using an efficient method to manage inventory systems is always a challenging issue in supply chain optimization. In supply chains including perishable goods, it is possible to reduce waste and other costs by identifying uncertain demand patterns and managing inventory levels at different stages of the supply chain. Considering the uncertainty and complex conditions of supply chains in the real world, in order to create a suitable model to express these conditions, various uncertain factors must be considered, each of which affects the supply chain inventory level in some way. In this research, a multi-level perishable supply chain model with uncertain demand, lead time and deterioration... 

Reviewing trends of energy consumption in the world reveals that sooner or later energy resources will be depleted. This concerning rate of consumption has brought about more greenhouse gases (GHG) emission influencing deleteriously on environment and climate. Human has continued energy consumption to maintain and improve the quality of his life through industrial production. Industry as a significant energy user owns considerable contribution to this consumption. Several attempts have been carried out to develop energy management systems in order to improve the energy efficiency of industrial sectors. Whilst they are comprehensive and could be applied to any sector, there is lack of... 

This research aims to study fundamentals of design as a science for possible use in special structures. Special structures are referred to those structures that designers’ knowledge for which are insufficient. Designs of such structures are complex in the sense that we lack all necessary elements of design matrix; as well as proper steps to reach the unknowns. Introducing appropriate design strategy for such structures; we show how a design could be developed without specific needs for trial and errors. In this work, various design methodologies and especially “Axiomatic Design” have been examined. In addition, functional requirement and associated design parameters for structural design are... 

Dynamic analysis of deploying elastic arms of spacecrafts carrying tip mass has been presented. The research concentrates on the precise analytical simulation to reveal the phenomena which are usually eliminated in estimations. One of the most important factors which affect the dynamic response of such arms is rigid body dynamics of spacecraft. Considering this aspect of the problem the evolutionary analytical simulation has been developed through three steps. The first step focuses on the minute simulation of the arm deployment, in which a new mathematical approach called "elastic profile" has been developed which leads to semi-analytical solutions for the arm carrying tip mass.... 

The behavior of boundary layer under the effect of the sweep angle is considered. The measurements were performed by a pitot tube rake. Three models with various sweep angels at angles of attack -2, 0 and 2 degree were tested. Both tip and root of all wings were closed by flat plates in order to prevent the flow to roll-up. However the flow field on the wing was still three-dimensional because of the sweep angle. The velocity on the wing has two components; longitudinal and lateral. The cross flow emerges due to the non-equilibrium of pressure and centrifugal forces. The velocity profiles showed that the magnitude of cross flow was stronger near the leading edge of the wing. The cross flow... 

This research attempts to develop the optimal solution for an inventory problem consisting of a single machine which produces items some of which may be defective. We assume that no shortages are allowed and all defective items are to be reworked. Setup cost for rework and waiting time of defectives are considered. This research consists of two different parts. In the first part we consider two different policies where in the first policy in each cycle after the regular production the machine is setup for the rework of defectives of the same cycle. In the second policy several cycles constitute a period. All the defectives produced in the period are reworked in the last cycle of that period.... 

Energy harvesters are used in today’s Wireless Sensor Networks (WSNs) to harvest the energy from the environment. One of the important advantages of the energy harvesting sensor networks over battery-operated sensor networks is that the use of the energy harvester prolongs the life time of the nodes, while a battery-operated node becomes useless once its energy runs out. Although an energy harvester can provide a supply source with a lifetime much greater than a battery, the amount of available energy for an energy harvesting system is a random variable and is not as predictable as the energy of a battery. This unpredictability may cause reliability problems. In order to solve the existing... 

Wireless Sensor Networks have become widespread because of their flexibility, applicability and ability to precept data with high accuracy. However, the most limiting factor in their usage is the amount of available energy in nodes since energy depletion in a node means that it is dead, therefore many efforts have been done for optimum energy management in Wireless Sensor Networks. In many cases, the key solution to prolong the network lifetime is load balancing. In this way, all the nodes will die (approximately) together and the lifetime of network will be maximized. Load balancing can be implemented in all layers from physical layer to application. It should be noted that it is not always... 

The competitiveness of a port convinced shipping lines and shippers with a significant basis in selecting a port. Port authorities and port operators can make use of the competitive advantage as a parameter for counter measures by grasping the advantages and disadvantages of the ports and be a prime factor of opportunities and threats of the ports. Ports have a significant role in today’s networked business environment. They are being regarded as hubs that are part of various logistic systems. The very essence of a seaport is to link maritime networks and land network. These networks for the port are means of analyzing its competitiveness. A port overall competitiveness is determined by it’s... 

Concrete is the second most structural material in the world. So attention and promotion of the concrete mix design with respect to variable issues and requirements, is very important. On the other hand, these days environment and its pollution has become very popular discussion. Waste-glass which is produced by human products is one of the environmental pollutants. In this thesis it replaces some aggregate in concrete and it can reduce the level of this material in the world. Also we study effects of silica-fume as cement replacement and properties enhancer in our concrete mix design and see how it can ... 

In recent decades the use of FRP materials for strengthening structures has been developed extensively, thanks to their high strength, sufficient stiffness, high durablity, and ease of use. A great deal of research has been conducted on strengthening reinforced concrete beams and columns with FRP composites. By contrast, not many researches are performed on slabs, especially two-way slabs. In these few researches, the loading and boundary conditions are limited to simplest ones. Therefore, in this thesis, the focus of attention is on strengthening reinforced concrete slabs under various loads and boundary conditions using FRP composites.
In this thesis, first, FRP composites and their... 

Supplier selection is a strategic decision that has a key impact on the success of the supply chain. Due to the nature of goods and storage conditions in the cold supply chain has a great impact on environmental pollution compared to other chains, and it also has the possibility of disrupting the chain due to the importance of temperature and time conditions. Currently, due to the spread of international pressures on the observance of environmental and social principles, the issue of choosing a sustainable supplier has been raised. Also, the expansion of supply chains has caused the challenges and risks faced by supply chains to expand and disrupt the chain, so the decision of supply chain...