فصلنامه پدافند غیرعامل
سال یازدهم شماره 3 (پیاپی 43، پاییز 1399)

Nowadays, critical infrastructures are more vulnerable to natural events, malicious physical and cyber-based attacks or intrusions. Since most societal functions rely heavily on critical infrastructures’ functionality, disturbances in any of them, can yield fatal consequences for interdependent infrastructures and subsequently, for the depending society. Therefore, critical infrastructure protection (CIP) has become an important research field in this century. In our country, to strengthen critical infrastructures and reduce the likelihood of willful attacks, possible vulnerabilities and negative consequences, it is imperative to consider the requirement of passive defense. Hence, critical infrastructure protection against any types of threats, as one of the goals of passive defense, would be achieved by developing and expanding appropriate strategies and guidelines. In this paper existing methodologies and national strategies for critical infrastructure protection is described. Resilience as a novel concept in common practices and strategies that have been applied in various countries to establish national protection plans, is investigated. In the concluding remarks, a set of strategic goals and also the most important challenges and requirements for developing critical infrastructure protection frameworks with a futuristic outlook are proposed. Thus, comparative research methodology is used to analyze the primary requirements of our national critical infrastructure protection strategy which could be counted as an effective step in achieving passive defense objectives.

Considering the establishment of management systems based on international standards (ISO) in the military industry and systematic implementation of activities based on the requirements of such systems, and in spite of the high importance of passive defense issues and sporadic official notifications, unfortunately in quality, safety, health, environment and other areas, passive defense issues have not been systematically dealt with, and the related requirements are not evident in the management system which would lead to irreparable damage. The research aim is the integration of the quality management system and the CCD at all stages of the life cycle of products in the military industry from design to decline in order to reduce the vulnerability of products, equipment, installations, personnel and property and also enhancement of the coping ability against enemy threats and dangers. After recognizing the CCD requirements relevant to the military industry and using questionnaires and averages calculations to take into account the expert opinions from the mechanics, electronics, system engineering and quality and passive defense fields and final summarization, crucial requirements were selected and merged with the quality management system requirements to achieve an integrated system.By comply with the requirements of passive defense along with the requirements of management systems, this proposed model of CCD integrate management system, is a model suitable for the military as well as civilian industries, to prepare them against threats and also guide them to take effective action to prevent or minimize possible casualties and losses while ultimately providing customer satisfaction.

The stealth technology is one of the most important strategies for protecting fighters and warships in the enemy's territory. Reducing the radar cross-section (RCS) of the antennas used in the radar of these fighters and ships is one of the stealth technology techniques. In this research, the methods of the radar cross section reduction for the microstrip antennas and their effects on performance of the antennas are presented. First, the radar cross section definition and the related governing relationships are presented and the importance of RCS reduction is discussed. Then, six main methods of radar cross-section reduction for microstrip antennas are introduced. These methods are: antenna shaping, electronic band gap (EBG), complementary split ring resonators (CSRRs), ground plane with frequency selective surface (FSS), metamaterial absorbers (MMA), and microstrip resonators. In each section, the radar cross section (RCS) of the reference and modified antennas are compared and the advantages and disadvantages of the relevant method is outlined.

Multi-agent systems (MASs) provide the possibility of prediction in critical situations by simulating the components of a complex system as intelligent agents and implementing its decision-making parameters. The main objective of this paper is to simulate the search and rescue operations for airstrikes (simulation of search, rescue and medical agents) and to increase the effectiveness of rescue teams in critical situations. Implementation of this system was carried out in district 3 of Tehran in three main phases: 1) prioritization of the area with the technique for the order of preference by similarity to the ideal solution (TOPSIS) in the GIS environment, 2) simulating the operating environment and establishing cooperation between the rescue groups by the AnyLogic software, and 3) creating scenarios and analyzing the different results. The infrastructure priorities’ map showed that 21 percent of the city’s blocks in the region were priority number one to enemy air attack and the other 18, 29, 22 and 10 percentages were in the second to fifth priorities, respectively.  Implementation of a simulator system revealed that, by doubling the number of rescue forces in different scenarios, the average time of operation was decreased by 47% and the number of fatalities decreased by 9%. The results indicate the value of using multi-agent systems in designing a search and rescue simulator system and modeling the decision-making components. The output of this article can be used to manage, decide, and predict the extent of the damage caused by air attacks.

Today, increasing the flexibility and strength of structures against explosions and impacts is one of the main concerns of governmental organizations across the world. The consideration of progressive destruction has added to the importance of structural strength against explosions and impacts in recent years. In this regard, most of the existing structures do not have adequate resistance and flexibility against explosions and impacts. The present study investigates the behavior of a one-sided concrete slab in four cases, including the reinforced and non-reinforced concrete, using glass-fiber-reinforced plastic (GFRP) plates in a gravity bearing building system on and under the slab explosive-loaded as a one-story structure with a span against direct explosive pressure. A TNT explosion model in the form of a 0.5-kg cube was applied to evaluate the deflection of the slabs in the ANSYS software which is capable of analyzing the explosion-load behavior of the structure. The loading parameters obtained from geometric modeling and other parameters required by the structure were modeled as 3D objects. The results indicated that the use of GFRP and carbon fiber reinforced polymer (CFRP) reinforcement plates were effective in reducing the displacement of the slabs due to the explosion load. They prevented the spalling and collapse of slabs and reduced slab displacement by 62%. In addition, an increase in the thickness of slabs, the diameter of GFRP bars, the number of CFRP layers, and their slab coverage percentage dramatically reduced the deflection of the samples.

One of the approaches to passive defense is to protect important buildings against progressive collapse. Progressive collapse is a phenomenon that happens in a building due to the removal of some structural members. In this research, the progressive collapse of a 26 story residential building in Tehran was studied by the alternative load path (ALP) method according to UFC 4-023-03. Several independent column and shear wall removal scenarios were adopted from the first floor. Nonlinear dynamic analysis was performed with SAP2000 software according to UFC to evaluate the bridging ability of the building on the remained members. Plastic joints in beams and columns were defined in special moment frames according to the instructions ASCE41-17 and FEMA356. Also, the shear walls were modeled by the multi-layer shells method and the mid column equivalent method. The results showed that correct relocation of the shear walls in a dual system within building guidelines leads to appropriate resistance to progressive collapse.

Space is the main element in creating social events. So, with the configuration of spaces and matching them we can perceive the spatial structure of the city, neighborhood, community, etcetera. The pattern of connection of spaces and associating them gives us different choices of spaces or streets to pass through. It reminds us that the street network is an element of the urban persistent infrastructure and somehow forms the social interaction and behavior. The old urban structures are part of the historical and cultural heritage of the cities and have a great value although with their organic street network they evoke a kind of confusion. Whilst in the past they carried their own semantic and identity values in turn, today they contain decrepit buildings, lost spaces, dark corners, step-backs and so on which is mainly the product of space configuration. This condition has provided the context for the occurrence of possible crimes and insufficient psychological security, or in other words, the creation of defenseless urban spaces. The method of this research is descriptive-analytical. Desk research has been used to organize the theoretical foundations of the paper, and the Depth Map and the GIS software as well as field observations have been used to analyze the data. As a result, it seems that by geometrical correction of the route axes (including the main structure of the neighborhood) and other organic streets and providing efficient access, it is possible to improve the movement of people. Moreover, by producing lively activities the Qatarchian neighborhood can escape desolation and survive.

The purpose of this study is to provide solutions to reduce environmental vulnerability in Zabol. For this purpose, after full introduction of Zabol city geographically, socially, culturally, economically and environmentally, 30 questionnaires were prepared and distributed among professors, PhD students and postgraduate students in environmental engineering and used in statistical analysis. External and internal factors evaluation matrix was used to evaluate environmental factors and SWOT analysis was used to determine appropriate solutions to reduce the 120-day wind damage. Results show that filing a complaint with the international community to halt the dam project on Hirmand in Afghanistan is the most important strategy to reduce vulnerability of Zabul City to the microdust phenomenon in order to promote national security. Subsequently, providing special facilities for farmers in Zabul and Sistan and Baluchestan province to use wasteland for agriculture, creating protected areas, banning cattle herding in the area prone to desertification on the western edge of the city, efficient drip irrigation technology and construction of settlements off the sand displacement path are among the key strategies to counteract this phenomenon and reduce environmental vulnerability. Also, to deal with environmental damage in Zabol city, in this study 20 strengths, 30 weaknesses, 20 opportunities and 30 threats were identified for the environmental situation. Accordingly, the environmental status of Zabul city in the defensive zone whilst facing dust storms was determined using the SWOT method and a set of appropriate environmental strategies with a defensive approach was presented.