فصلنامه پدافند غیرعامل
سال سیزدهم شماره 1 (پیاپی 49، بهار 1401)

Since 1973, the steel shear wall system has been considered by researchers and structural designers as a lateral resistance system. This lateral resistance system has shown good performance against threats. According to the cost-benefit principle in passive defense, the results of a study on the behavior of shear walls show that the steel shear wall system will save about 50% in steel consumption compared to the flexural frame system. Since the purpose of passive defense is to reduce the vulnerability of assets against natural and man-made threats, the steel shear wall system as a lateral bearing system, in addition to being light compared to concrete shear walls, has high hardness and ductility, and in addition to Reducing the effects of the natural threat of an earthquake will also work effectively against man-made threats such as bombs and missiles and its effects, such as blast waves. Despite its high efficiency, this system has not been used significantly in Iran. In this article, various responses of thin steel shear wall system without stiffeners against lateral resistance have been investigated and the effect of three main parameters of this system has been studied. These three parameters are: beam-to-column connection type, stiffness of the beam and column (the stiffness of the border points of the frame) and the thinness ratio of the sheet (the ratio of the distance between the center line of the column and the thickness of the sheet).

In computer incidents, the benefits of the attacker’s (defender) strategy depend heavily on the performance of the defender (attacker). Thus, the effectiveness of the crisis management mechanism relies on the strategic behaviors of the defender and the attacker, and the use of an effective tool, based on information technology can lead to a significant increase in the efficiency. The DoS attacks based on bandwidth reduction are a constant threat to network security. The proposed methods, due to the lack of quantitative approaches in modeling defense strategies against these attacks, cannot solve the problem effectively. Game theory can provide a framework for modeling such attacks. A game theory-based model can act as a decision support system for the defender and enhance its ability to make the best decisions to maintain an optimal level of network security against such attacks. In this paper, a proposed model for responding to the DoS attacks, based on game theory, is presented as a game between attacker and defender. The network is also modeled and the efficiency is calculated. The results show that the game converges to the Nash equilibrium and the best action is inferred from this strategy. The results obtained by simulation and numerical calculations are in favor of the proposed theoretical defense mechanism of the game and support the merit of using game theory to defend against DoS attacks to strengthen network security.

In this study the kinetic projectile with double nose in concrete targets by considering the velocity effect on friction between projectile and target is investigated. Numerical methods and finite element solution were used to calculate the depth of the penetration. In the numerical solution method, by integrating the stress at the nose surface and calculating the force on the nose of the penetrating projectile, the penetration depth of the projectile was calculated using Newton's second law and numerical methods were used to solve the resulting differential equations. In the finite element method, the Concrete damaged plasticity structural model was used to model the behavior of concrete, and in both the finite element method and the numerical solution method, the static-dynamic exponential reduction model is used to model the frictional force on the projectile. In order to develop the penetration depth equations, the parameters and equations related to the exponential friction coefficient have been considered and the two-step nose penetration depth equation has been developed by considering different parameters. To validate the proposed model, the results of experimental projectile penetration tests with the shape of the nose of other researchers have been used. Considering the effect of speed on the coefficient of friction between the projectile and the target has significantly increased the accuracy of speed calculations in this research.

In recent decades, structures have been of special importance in terms of defense against natural and man-made disasters. Therefore, the need to build structures with high strength has been one of the concerns of engineers in this field. Concrete as one of the main materials used in concrete structures, has an effective role in improving and enhancing the strength of structures. Concrete resistance to falling weight is known as one of the mechanical properties of concrete. In this laboratory research, a mixing design was made of ordinary concrete with a cement grade of 450 kg / m3. 500 degrees Celsius, compared and evaluated at 90 days of processing age. Next, X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM) tests were performed to further evaluate and validate the impact resistance test results at 90 days of processing time at ambient temperature and 500 ° C. Samples were taken. In the results section, the amount of energy absorbed in the impact test of weight drop at ambient temperature was 244.24 joules for ordinary concrete and 223.89 joules for quilted concrete, which were subjected to high heat application in concrete. They showed a decrease of 90.9% and 72.72%, respectively. The flexibility index in this test under ambient temperature was 2.33 joules for ordinary concrete and 1.58 joules for reinforced concrete, which under high heat in concrete, improved by 28.75%, respectively. They showed a drop of 9.49%. The results of XRD and SEM tests were in coordination with each other and overlapped with the results of impact resistance test.

Agroterrorism in natural resources mainly involves using various biological agents such as fungi, bacteria, viruses, and insects by terrorist groups to destroy forest trees and natural resources, create fear, economic losses, and reduce socio- political stability. Successful counter-terrorism policies have led to restrictions on the activities of terrorist organizations resulted, agroterrorism attacks increased. The increase of such threats is directly related to the progress of genetic engineering and biological science methods, which the adversaries exploit. In such situations, agricultural and natural resources research institutes are in a unique position to assist information and military organizations. They can identify threats and use agricultural biotechnology and plant immunology to strengthen the safety of products against pathogens. The purpose of this research is to show how passive defense can be used as an indicator to emphasize the increase in the ability to prevent, detect and discover, react and recover natural resources against agroterrorism actions. This research was descriptive, analytical and practical in terms of type, and the sample population based on Cochran's formula included 108 professors and students in the field of natural resources. After collecting the information, a questionnaire consisting of 11 questions related to the research variables was prepared. The results of the research showed that passive defense can quickly prevent the spread of damage and destruction in the field of natural resources by timely detection of the threat. Passive defense with the provision and operation of the central laboratory, careful monitoring of the country's borders, periodic and regular monitoring of various regions, and the creation of databases will be effective.

Finding the principles of passive defense from the perspective of verses and hadiths to deal with Subsistence crises is a necessity for the individual and society. Economic crises are caused by human factors (such as war, sanctions and economic blockade) or natural factors (such as famine, earthquakes, floods and droughts). The present research has explored the ways of immunity against economic threats, damage and attacks. In the following, by examining the verses of the Holy Quran and analyzing the validity of the extracted components, it has been tried to present and explain operational solutions to stay safe and defend against Subsistence attacks in the two areas of insight barriers and behavioral barriers. According to scientific researches in the field of passive economic defense, another mission of this article is to compare the results of those researches with the discovered Quranic narrative solutions. Prioritizing the deterrents against threats to Subsistence according to the weight of the relevant verses and presenting it in the form of tables and graphs is one of the achievements of this article.

Today, reducing the vulnerability of urban land uses to reduce the amount of damage is one of the most important objectives that city planners and managers are trying to achieve, which is important by using new approaches to crisis management such as passive defense. It is achievable and can be effective in creating a safe environment in cities. Urban flood risk mapping is a new tool that can be used to identify development sites to reduce public risk and damage to land uses. These maps show the condition of residential areas and other uses in relation to floods and state that flood control operations and flood warning systems should be considered in areas that are highly vulnerable. In this research, flood prone areas in the return period of 2, 5, 25, 50, 100, 200 and 500 years in an interval of 5.8 km from the Dez River bed in the central area of ​​Dezful city using HEC-RAS model and ArcGIS software was prepared, for this purpose digital maps with 10 meters accuracy, discharge statistics of Dezful regulatory dam hydrometric station and river morphology features were used in the study area. Since the Dez river basin is a flood zone with a return period of 25 years, the results showed that the maximum depth and speed of water during the flood with a return period of 25 years are 19.47 m and 7.43 m/s, respectively. For the return period of 2, 5, 25, 50, 100, 200 and 500 years, 65.6, 106.3, 1.154, 1.168, 180.6, 192.4 and 208 hectares under flood cover, respectively. It is decided that due to the existence of residential areas and resort uses on the banks of the river, it is necessary to carry out flood control operations and flood warning systems in the parts where more vulnerability is predicted, and in order to Necessary measures should be taken to remove the illegal possessions that have taken place in the bed and privacy of the Dez river.