فصلنامه پدافند غیرعامل
سال یازدهم شماره 2 (پیاپی 42، تابستان 1399)

Some of the main goals of passive defense in times of urban crises are timely relief and applying proper crisis management practices such as evacuating the city and removing traffic jams to keep people away from danger. Therefore, public transport systems in urban areas during emergency evacuation are important assets and play important roles in the evacuation operations. One of the public transportation systems in Tehran is the urban rail transport system which has been developed in recent years and its variety and flexibility effectively influences rapid emergency evacuation. Due to the importance of the matter, the aim of this research is to investigate the role and capacity of the metro system in emergency evacuation of Tehran city and to provide solutions for crisis management in emergency evacuation. Hence, previous studies on the role and analysis of the capacity of the metro lines are inspected and then the role and capacity of the metro systems in the discharge of Tehran city population are analyzed according to scenarios of the city pathology and specification of departures and destinations. Finally, crisis management solutions are provided to facilitate and accelerate the emergency evacuation of the population in Tehran using the subway system.

Explosions at the entrance of tunnels and underground spaces can lead to losses. To decrease side effects of such explosions, some approaches like dead_end, bends, geometric barriers and anti-explosion doors are available. Using geometric barriers, especially the waveguides, is the most commonly used and economical way. The purpose of this paper is to investigate the effect of the angle of rotation of the longitudinal axis (bend) and the local variation of the tunnel area on reducing the impact of explosions. Appropriate angle of rotation of the longitudinal axis and suitable location for local variation of the tunnel cross section in line with the tunnel are calculated, by numerical analysis, using Abaqus software.  Finally, proper characteristics are used to propose a method, requiring the least drilling in construction (the most economical method), and generating the highest reduction in the effects of the explosion (the highest vulnerability reduction) in explosions near and away from the span. The results show that the localized change in the tunnel cross-section at the end of the direct path and the change in the angle of rotation of the long axis from 135 ° to 90 ° (90 °) will lead to the greatest reduction in pressure.

Today, discussing, identifying and preventing casualties, and economic and social losses due to natural disasters such as landslides, floods, and earthquakes are of particular interest to official authorities and scientific and research communities in most countries. The occurrence of landslides can be closely related to other natural disasters such as floods and earthquakes, and these phenomena have a significant role in the development and severity of landslides. In this research, lithology, distance from the fault, slope, elevation, land use and coverage, distance from rivers and distance from the roads are considered as the factors affecting the occurrence of landslides and the Fuzzy-AHP method is used. The study area is located in the northwest of Iran, in the East Azarbaijn province, in the area of Maraghe and Hashtrood. The length of the Maraghe-Hashtrood highway is 92 Kilometers, the second part of this highway is 26 Kilometers. The main reason that this location, as the area of study, is classified as a medium to high risk zone is mainly due to the highway rocks type, which are sedimentary and weak in erosion. Proximity of the study area to streams and dispersed vegetation, also exacerbates the risk of landslides.

An earthquake as a natural phenomenon is a risky and crisis-making event that by not being prepared to face it, makes the society vulnerable. The experience of earthquakes in our country has shown that there is no readiness to deal with this natural phenomenon in the country. In such circumstances, an earthquake occurring in one of the big and crowded cities of the country such as Tehran, can lead to irreparable damages. On the other hand, if it is not possible to prevent an earthquake, it is possible to reduce the damage it causes, and most importantly to save people's lives against this natural occurrence. In short, the earthquake vulnerability of the city of Tehran especially the 2nd district, and the importance of maintaining the safety and security of citizens as one of the most important goals of urban planning, highlight the necessity of this project.In this research, the theoretical framework was carried out by collecting information through library and electronic resources and articles. The vulnerability of the urban structure to earthquakes was studied with the passive defense approach, based on experts' opinions and review of previous studies, and the dimensions and suggested criteria were determined. Then, the paired comparisons of indicators were carried out with the help of 15 faculty members and experts specializing in environmental planning, urban planning, rural planning and urban engineering. Their valuations are based on their experiences and studies. After the pair comparisons, the maps of the factors affecting the vulnerability of the urban structure of the area were standardized in the Idrisi environment, and the weight of each of the effective measures influencing the vulnerability of the structures in the layers, were applied in the GIS environment. Then the maps were combined to determine the vulnerability of the urban structure to earthquakes; the passive defense approach applied.

Nowadays, with the widespread use of the Internet, one of the great challenges of communication networks is the access speed. The speed of access becomes a challenge when different devices connect to a wireless network. Wi-Fi networks are facing some problems, such as difficult or impossible connectivity in some places and a speed far below today's needs. In this research, while introducing Li-Fi technology, where the data is exchanged wirelessly through visible light, its features and limitations are studied. The architecture and scientific relations and mathematical models of this new technology are also presented. There are new ideas and applications for the Li-Fi that are explored in this paper and finally, Li-Fi technology is compared to Wi-Fi technology based on various parameters.

This article mentions that safety and security have been the most important concerns in the design process of nuclear power plants. Surveying the building form of these complexes shows that most of them have a dome-formed structure in their design. Therefore, the goal of this study is to specify why this form is prevailing in the design of nuclear power plants. The research method is based on the theoretical survey of the relevant standards and also the experimental survey of the existing power plant design. The results have indicated that confining the radioactive materials inside the building, preventing any leakage, avoiding the internal and external hazards, accommodating the active and passive safety systems, as well as reducing the pressure and temperature of internal air in LOCA events are the main intended safety/security functions of these one or two layered dome-formed structures, only some of which are actually realized.

Most of the destructive effects of blast loading on structures can be found in the form of local failure of structural members. Such local damages could be associated with progressive collapse of the whole building. Progressive collapse, which has caused widespread casualties and financial losses at the blast events, can occur as a result of the sudden collapse and removal of structural columns under direct effect of the blast pressure. Therefore, assessment of the blast response of RC columns and their retrofitting against blast loading would provide very useful information in the field of blast resistant structures. In this paper, using a validated FE modeling process, square RC columns and RC columns strengthened with steel jacketing under blast loading, are analyzed by the explicit solver of ABAQUS software package. By performing nonlinear dynamical analyses, the explosive response of simple and strengthened RC column models are compared in terms of maximum displacement values ​​and absorbed energy. Obtained results show that retrofitting of RC columns with steel jackets, significantly reduces the energy reaching the structure and the deformation, and improves the performance against blast loading.

Threats are essential. The purpose of this study was to evaluate the risk of concrete hydrocarbon dams against human threats, which is considered as an applied research. In this regard, librarianship, interviewing and viewing methods have been used to identify threats to dams and extract damage caused by their occurrence and provide non-operational defense considerations, and to prioritize threats, vulnerabilities and value Assets were also used to collect information using a questionnaire. Therefore, the research method of this paper is a descriptive-analytical method. Content analysis (qualitative) and descriptive statistics (quantitative) were used to analyze the data. Expert Choice v11.0 and SPSS13.0 software was selected as the data processing tool. The findings of the research showed that the threats of air strikes, missiles and militias were considered as the main threats to dams. By implementing risk assessment components on a case study (Lerro Dam), the dam and overflow risks and building of the dam's power plant were at the highest risk Has been accompanied. The risk assessment methodology used in this study is using the FEMA and RAMCAP compilation method, which consists of three basic components (asset value determination, threat screening and vulnerability and risk assessment), which has been tried briefly in this research. They will be introduced to them