simulation

Today, the use of tunnels is one of the favorite strategies of armies as well as guerilla forces, and in many cases it is considered one of the important factors of victory. Due to the high contrast of the specific electrical resistance of tunnels with the host environment, the specific electrical resistance method can be called as the most powerful near-surface method for detecting such structures. In this study, conventional electrical tomography arrays have been simulated in order to detect tunnels using the forward modeling method. Based on the obtained results, the dipole-dipole, polar-dipole and Wenner-Schlumberger arrays have the best response in their sections to the presence of the tunnel, and the Wenner array has a weaker sensitivity than all of them. Also, in this study, based on the principle of changing the geometrical  parameters (depth and size) of the tunnel as well as the conductive overburden, solutions have been proposed to hide the tunnels from the field of view of the arrays.

The purpose of this article is to investigate the resilience of Mehrabad airport in possible crises such as war and earthquake through the simulation of emergency population evacuation. The research method is descriptive-analytical, in terms of solving the combined problem and the type of explanatory results. . Collecting field and documentary information has been done. The statistical population includes 160 specialists, academic staff and graduate students. Random sampling and Cochran's formula were used. After conducting the interview and completing the questionnaire, compatible scenarios are obtained from Wizard software and then modeling in normal, disaster and optimistic mode with maximum two incompatible factors is considered in Any Logic. The results of the simulation have shown that the fourth scenario is in a more critical condition than the other scenarios with an evacuation time of 125 minutes and a simulation time of 87.19. In scenario 1, normal conditions, since all entry and exit doors are healthy, the percentage of evacuation of people is maximum immediately after the beginning of the crisis, the presence of obstacles has no effect on the creation of a population node, and over time, the population gradually leaves. In the case of a disaster, time Draining is 100 and simulating 59.11 minutes. The resilience of airport hall number 2 is suitable under normal conditions, but in the event of a crisis and an increase in density, fear and speed, it is very low. Unlike the previous studies that have a one-dimensional view of the emergency evacuation issue, this article has a mixed approach.

Systolic architecture is one of most important parallel processing architectures.In the systolic array, ALU units are arranged as an array. This array acts synchronously and executes the recursive equations in parallel by applying the proper input. In this paper, the systolic array for the SL0 is designed and simulated. Simulation results showed that the implementation of this algorithm with a single processor, assuming 4 clocks for executing each recursive equation, requires 4N ^ 3 + 9.7N ^ 2 + 3.2N + 18 clocks, while doing it with a systolic array requires 48n + 32 clocks due to parallel computing and pipelines.

In this study, the feasibilityof using the Ground Penetrating Radar (GPR) method to detect and locate subsurface utilities in various conditions has been investigated. To do this end, the performance of radar waves in detecting different material types in environmental conditions with different electrical conductivity has been studied. The GPR's performance criterion in this study is the resolution of the reflected waves in using radar systems with different central frequencies. The results indicate that the central frequency has a great influence on the size of the target with proper imaging. Moreover, the simulation results show that for central frequencies of 50, 250, 500 MHz, 1 GHz and 2 GHz, targets with sizes 125, 25, 6 and 3 cm cannot be detected, respectively. Estimated results on resolution are related to the radar wave propagation velocity in the media severely. Also, the estimated resolution values are valid for a medium with a wave propagation velocity equal to 0.15 m/ns (For example, alluvium with moderate grains or dry sand). Simulation results on martial type based on relative electromagnetic permittivity (Ɛ), sub-layer conductivity (δ) and layers thickness (D), show that the electrical conductivity had a higher effect on the GPR results with respect to the other parameters and layers with an electrical conductivity of less than 0.1 ohm-meter strongly weaken the amplitude of the transmitted wave and made it difficult to identify the target. Results show that with changing the central frequency in the GPR system, transmitted and reflected radar waves have different frequency content and pulse width in both frequency and time domain. As it is presented in the paper, short pulse width in time domain led to a broad band in frequency domain. Simulation results on substance type which is simulated by relative electromagnetic permittivity (Ɛ) parameter show that high relative permittivity led to receiving a reflected signal with high frequency content in frequency domain and recording strong amplitude in time domain. The simulation results show that soil conductivity attenuated electromagnetic waves severely. Based on simulated data for a target located in 1 m depth and a GPR system with dominant frequency equal to 500 MHz media with electrical resistivity more than 20 ohm.m does not affect the signal quality in radar waves. However, decreasing electrical resistivity by less than 2 ohm.m caused lack of penetration and without receiving any reflection from the target. The simulation results concluded that, using a GPR system in normal condition such as soil with 100 ohm.m, target and media relative permittivity respectively equal to 80 and 4 and target depth located in effective depth, reflected electromagnetic waves are recorded in different resolution. As results for 50, 250 500 and 2000 MHz central frequency 125, 25, 6 and 3 cm resolution is calculated respectively. Estimated results on resolution is related to radar wave propagation velocity in the media severely. Estimated resolution are valid wave propagation velocity equal to 0.15 m/ns. In the second part oof this study 2D simulation is performed. 2D simulation conducted for four different conditions. In all conditions 3 layers and 3 target is simulated. Ground penetrating radar data is simulated based on central frequency 50 MHz.  Finally, 2D simulation, synthetic cross-sections indicated that high conductivity of soils cause the less penetration and low-resolution results. In addition, attenuation parameter investigations show that value of high attenuation in silt and clay soils by two and four cause the very low-resolution data in ground penetrating radar method.

Nowadays, one of the most common methods for water transmission is through underground tunnels. Tunnels are in line with the fundamental principle of the passive defense for protection of water resources and are able to prevent any potential risks to water transmission lines. In this research, a numerical study has been employed to investigate the effects of surface explosion on the water transmission tunnels. Herein, by changing the distance of explosive materials as well as the thickness of concrete segments, response displacements and explosion effects on the concrete segments have been calculated. For this purpose, three concrete segments with the thicknesses of 0.2, 0.3 and 0.4 m were selected and subjected to the explosive materials located 0.5, 1 and 2 m away from them. The obtained results showed that the concrete segments with the thicknesses of 0.2 and 0.3 m experienced significant damage when subjected to 20 lb. explosive material at the distance of 0.5 m. It was found that burying the structures or embankments of the structures were among the best methods for damping the blast waves.

There are many methods for converting the beta particle energy to electrical energy. Conversion of the beta particle energy to the electrical energy using semiconductors, is one of the important methods that can be used in radioisotopic batteries. In this work, a photo-betavoltaic semiconductor battery has been designed and constructed. The battery produce electric energy by converting photon energy from the sun or kinetic energy of beta particles. Doping process of silicon to fabrication of the p-i-n diode has been investigated. Thus, diffusion of dopants in 1000°C, SEM analysis, calculation of doping concentration, calculation of the diffusion depth and electric resistance of the doped silicon have been investigated. The measured betavoltaic current was 50 pA for a 58 μCi 90Sr/90Y. The photo-betavoltaic battery has been simulated by Monte-Carlo MCNP5 code and 45.2 pA electric current has been obtained. A fairly good agreement was observed between experimental and numerical results. Also, this battery is responds to visible light, sensitivity of which is comparable with the sun cells.

With the increase in using cyber space in organizations, cyber-attacks specially DDOS attacks by malware and intruders have increased. According to limits that do not allow the terms of a cyber attack to be created in organizations, in addition to providing information about systems at the time of the attack, using simulation provides the possibility of a wide variety of attacks with different sizes. Agent-based modeling and simulation is a method for simulating systems comprised of different agents. In this article, in addition to describing the concepts and features of the agentbased modeling and simulation and DDOS attack, the necessary conditions to examine the various scenarios of distributed interactive and non-interactive cyber attack and defense and evaluation of its performance is provided. The results show that the Defense Distributed Interactive has a better performance than non-interactive mode and the load at the time of the attack is reduced to an average of 15 percent. This reduction of traffic load is due to interaction of defence agents with each other that subsequently increases the defense capability of agents when the attack occurs.

About a quarter of a century has passed since the IRAK-IRAN war but unfortunately، some areas of the country still remains contaminated by mines and unexploded bombs and sometimes irreparable damage is inflicted. Due to the limitation of magnetic mine detectors، penetration depth should be estimated with reasonable accuracy. In this paper، the mathematical model of the bomb motion in the air and soil is written. The bomb motion is simulated based on TM and military handbook with MATLAB. Then UXO penetration depth in Azadegan oilfield was Investigated as a case study and simulation results are compared with MIZUHO results. The effect of the bomb angle of attack in the penetration depth is also determined. Finally، regarding all effectives parameters، the correct depth is estimated and invalidity of MIZUHO results is shown. Subsequent excavations carried out in the field and non-observation of UXO in more than six meters deep proved obtained results.

Metamaterials are artificial composites that acquire their electromagnetic properties from embedded subwavelength metallic structures. In theory, the effective electromagnetic properties of metamaterials at any frequency can be engineered to take on arbitrary values, including those not appearing in nature. As a result, this new class of materials can dramatically add a degree of freedom to the control of electromagnetic waves and open new vistas in military camouflage and offer the possibility of target's perfect cloacking. In this paper, we firstly introduce active and passive metamaterials and then we simulate them with arbitrary shapes.