Stratification and prioritization of assets from the point of view of passive defense (Case Study: Tehran)

Introduction:
Key assets include systems and assets, whether physical or spiritual, which are necessary for a system and any disruption in its services can have a serious impact on national security, economic well-being, public health or safety. , or a combination of them (zhang et al, 2015:7). Looking at the recent wars, including the war of the occupation regime of Al-Quds against Hamas and the war between Russia and Ukraine, we come to the conclusion that the enemy's attack has always been focused on key assets in order to reduce the ability to defend the country with the least cost and power. Invasion, take away and in the destruction strategy, the centers of gravity of key assets are located in the primary rings, and in case of malfunctioning and being threatened, the possibility of providing services will be denied.
Cities and metropolitan, due to the high volume of investment and establishment of many establishments and centers of gravity and vital arteries, suffer significant financial and life injuries in the event of man-made threats (Abazarlou, 2015: 31). In metropolitan cities, the damage caused by man-made threats on key assets includes a combination of physical damage and disruption of the functioning of urban elements. Destruction of structures and buildings, road and access network, basic facilities of water reservoirs, power plants, communication lines of telephone, electricity, water, gas, etc. are among them (Hosseini et al., 2010: 46).
Passive defense is considered as a platform for sustainable development and one of the most effective and sustainable methods of defense against threats and includes different areas of urban spaces. This type of defense includes five main objectives; It follows increasing deterrence, reducing vulnerability, continuing necessary activities, promoting national stability and facilitating crisis management (Ghazanfari, 2012: 45). In this regard, the objectives of the research are as follows:
1. Identifying the key assets of the case study
2. Evaluation of the value of the key assets of the case study

Research Methodology:
In terms of the type of research, the present research is considered as applied research and in terms of research method, it is considered as descriptive-analytical research. According to the goals and questions of the research, in order to collect information, library studies and questionnaires are used. In this research, the FEMA (American Emergency Management Agency) technique has been used to evaluate the value of key assets of a case study.

Discussion and findings:
- Leveling of key assets of the case sample
In this section, through interviews with project experts, the key assets of Tehran city were counted and identified, which are:
Mehrabad Airport (1), Milad Hospital (2), Tehran No. 6 Treatment Plant (3), Azadi Stadium (4) and key administrative centers (Islamic Shura Council) (5) which are based on the guidelines for leveling centers of gravity. It was leveled according to table (1). The results of the research show that Mehrabad Airport and key administrative centers (Islamic Council) with a sensitive level and Milad Hospital, Tehran No. 6 Water Treatment Plant and Azadi Stadium are among the important assets.
-Evaluation of the key assets of the case study
Key administrative centers (Islamic Council) with a score of 9.54, Mehrabad Airport with a score of 9.204, Milad Hospital with a score of 8.539, Tehran's Sixth Treatment Plant with a score of 7.712, and Azadi Stadium with a score of 6.273 have high value.
According to the FEMA technique in the evaluation of key assets, the rating scale of assets and specifying the grouping of each asset is done.

Conclusion:
Key assets as one of the existing uses in cities, due to their attractiveness and the possibility of being targeted by enemies, need to be developed in the context of passive defense in order to minimize their vulnerability. The purpose of this research is leveling and prioritizing the value of key assets of Tehran city.
In this research, based on the opinion of experts based in Tehran, Mehrabad Airport, Milad Hospital, Azadi Stadium, Islamic Council and Tehran's 6th Refinery were introduced as key assets.
In the following, according to the approved guidelines for the leveling of centers of gravity of the inactive defense organization, Mehrabad airport and key administrative centers (Islamic Council) with a sensitive level and Milad hospital, Tehran's No. 6 treatment plant and Azadi Stadium are among assets with a significant level. to be
Also, to prioritize the value of the key assets of the case sample, the FEMA evaluation technique was used, and the research results show that key administrative centers (Islamic Shura Council) with a score of 9.54, Mehrabad Airport with a score of 9.204, Milad Hospital, respectively With 8/539, Tehran's sixth refinery with 7/712, and Azadi Stadium with 6/273 have high value.
In comparing the findings of the current research with previous researches, it is worth mentioning that in previous researches, no process and guidelines were adopted for how to level and prioritize the value of key assets, and only based on expert opinions. And the quality of this issue has been covered, but in the current research, the instructions for leveling the centers of gravity and the instructions for assessing the value of the inactive defense organization's assets have been used, and the results are more accurate.
Key words: assets, passive defense, Tehran city, asset leveling, asset prioritization, FEMA technique