m. fayyaz

The retrofitting plan is effective when, in addition to being cost-effective, it minimizes casualties, reduces infrastructure damage, and limits the extent and scope of damages as much as possible. The design and construction of most explosion-resistant barriers in all types of structures are not optimal due to the high cost on the one hand and the low probability of explosion during the life of the structure on the other hand. In this research, the proposal of using the combined method of restraining net along with the blast wave absorber panel as a new model in protecting the building against external explosions has been studied. The rocket is restrained at a certain distance from the main structure by a resistant net and the panel absorbs the wave caused by the explosion. By conducting studies and experiments on various absorbent materials, the selected panel was introduced and its behavior against threats at different distances was evaluated numerically and in the field. The results of the simulations were in good agreement with the field tests, which can be generalized for different amounts of charge.

Concrete canvas rolls have several unique properties have made it a strategic material. A major property is rapidness of installation that can be considered in the construction of accelerated shelters of protection against threats. The use of concrete canvas in the construction of the shelter is also expanding worldwide due to its economic benefits and the speed of its installation, as experience has shown that a two-person team can build a shelter with an area of 25 square meters of concrete canvas in less than an hour. Increasing attention to this function of concrete canvas requires studying product behavior against incoming loads, and the need for a deep understanding of the material and components of aerated concrete leads to a better understanding of this product and the possibility of improving product quality. Therefore, the properties of two-phase concrete canvas, including fabric and mortar that have structural performance, were studied using Abacus finite element software. The results of finite element simulation on macro and Meso scales were compared with the laboratory results of different samples, showing the accuracy of the study. The results illustrate that the use of fibers with higher tensile strength and high Young's modulus and stiffness has a better performance against the applied loads. The shelter behavior is evaluated against different probable attack scenarios. The designed shelter is capable of withstanding slag up to a height of 70 cm of soil, which also makes it resistant to mortar attacks. The use of a concrete canvas shelter without any slag also makes it resistant to the 5 kg TNT threat at a distance of 3 meters. Using products against larger threats or loads strengthens the shell with appropriate materials or several layers of concrete canvas shells.

With the increasing development of concrete structures, properties such as strength and durability of concrete have become particularly important. Therefore, it is necessary to use special concretes and obtain new combinations. Ordinary concrete is brittle and frangible, and if rebar is not used, other materials such as fibers should be added to the mixture to remove the brittleness of the concrete. Fiber is used to control cracks in concrete, which in addition to controlling cracks, improves impact resistance, fatigue, shear, bending, as well as energy absorption of concrete. In this research, fiber concrete made of steel, barchip, and macro synthetic fibers and the combination of each fiber with different volume ratios is subjected to explosive load and the failure rate of each sample and the resistance of fiber concrete with hybrid fibers to explosion have been investigated in laboratory and field. Also, the special electrical resistance of hybrid fiber concrete against the electric current has been evaluated, which can be considered as a measure to evaluate the permeability and parallel absorption of concrete water. The results showed that concrete with macro synthetic fibers had greater explosion resistance than other samples. Also, the electrical resistance of concrete with macro-synthetic fibers has been higher than that of other samples, which will have special applications in corrosive areas with high penetration of chloride ions due to higher electrical resistance and consequently lower permeability. Also, for estimating the cost of fiber performance in concrete, the lowest excess cost of using fibers in concrete was related to the use of 1.5% of the concrete volume of macro synthetic fibers due to the low cost of these fibers and its high resistance to electrical resistance and resistance to explosive load. The use of these fibers in concrete to withstand explosion and electric current has been cost effective.

In recent years, with the increasing number of terrorist attacks and explosions in structures, extensive studies have been carried out on the performance of structures and their reactions under blast load. Due to the importance of the pile in the load transfer of various structures such as wharves, oil platform and bridges it is essential to study the behavior of this member. In this research, to minimize the damage caused by the blast load and the waves caused by the blast, the behavior of steel piles in two types of loose and dense sandy soil was investigated by Abaqus. The modeled pile is placed under different blast loads at 5 m distance from the pile head (at the soil surface) and the end of the pile (at the soil depth) has been studied. Finally, it was observed that the bending moment pile in dense sandy soil was significantly more than bending moment pile in loose sandy soil. The horizontal displacement of the pile head when the blast occurred at the soil surface is far greater than the displacement of the pile head under the blast load.

The trust inference problem in a social network is defined as anticipating the trust level that a user can have to another user who is not directly connected to him on the trust network. This research aims to propose a method for trust inference in a trust network. Previous research studies are mainly limited to one type of trust network, and they cannot be used for different trust networks with different values of trust. In this research, soft computing and neural network model are used to predict trust values. To train the neural network system, genetic algorithm is exploited. One of the main advantages of the proposed method is that, unlike previous methods, it is not limited to one type of trust network, and it can also be used for trust networks with different values of trust. In the proposed method, at first four proposed features are extracted from the trust network, and afterward, the proposed neural network system is trained using these features as well as the genetic algorithm. The proposed method is implemented on the standard trust network and is compared with other similar methods. Experimental results indicate that the proposed method is able to produce more accurate results in comparison with previous methods.

Analyzing of shape, location and other properties of propagating waves involve complicated boundary conditions, nonlinear equations, variant domain and intensive effect of various flow phases on each others. These properties have made waves modeling one of the most complicated computational problems. In this research a Lagrangian, multiphase, meshless and three dimensional method called MP-MPS (Multi Phase Moving Particle Semi-implicit) have been developed based on the MPS method. The MPS method is applicable in solving turbulent flow equations such as prorogating near shore waves. In the multi phases model of MP-MPS the three dimensional and viscous equations have been extended for three phases of gas, liquid and solid. In this way different phase’s counteraction effect have been exerted in the equations by some variables, so the phase changes are modeled synchronically. The dam breaking and wave propagating problems have been applied to show the ability and accuracy of the model. The results have been compared against experimental and analytical models. Comparison of model results against applied methods of primary researches represents the accuracy and applicability of modified methods and algorithms deployed in the developed model.