فصلنامه پدافند غیرعامل
سال چهاردهم شماره 3 (پیاپی 55، پاییز 1402)

Human life has always been in danger throughout history, and the struggle for survival has always made man inevitably prepared. Threats are both made by man or are natural. The type of exposure to these threats has different forms throughout time and space. This study has selected the Central Plateau region of Iran to understand the respond to the threats in this area.The Central Plateau of Iran, with its hot and dry climate, covers a large part of the territory of Iran and, due to its climatic and geographical characteristics, has its own security considerations. This study aims to understand the defensive methods of the Iran historic cities in the Central Plateau region of Iran and the article seeks to find the defensive methods of the past in comparison to present principles of passive-defense.The research has done using documentary studies and qualitative analysis method. The results show that although the principles and characteristics of defence in the historical cities of this region have been proportionate with the threats of its time, but also with many principles of today's passive-defense, include location, the optimal scale of population and activity, dispersion, camouflage, concealment, cover, deception, and dual-purpose structures. By providing additional facilities, other principles such as "optimal scale in dispersion and special economic justification," "downsizing and cheapening and initiative in passive defense ,"  "division," "dispersal," and "deception" can be provided, too.

In this research, at first, different types of trenches, headquarters and concrete hospitals during the holy defense were investigated from the perspective of commanders and specialists of holy defense. In order to investigate in addition to library studies, the performance of these structures has been investigated through interviews and questionnaire distribution among veterans in the field of sacred defense engineering and after aggregating the opinions, general analysis of the role of these structures, their technical disadvantages and advantages has been presented and then some strategies have been presented to promote these types of structures for today's use.One of the main disadvantages of them is the heavyness of prefabricated concrete parts and one of the solutions provided for today's use is to increase resistance to bearing impact loads. In a numerical analysis, the effect of increasing steel fibers on concrete slabs under impact load in Matlab programming environment has been investigated. The results show that the use of steel fibers up to 2% increases the ductility and strength of concrete to a great extent and is recommended for use in war zones.

The design of elements under blast load came to the attention of scientists after World War II. Extensive research has been done in the last fifty years on the behavior of structures against blast loads and their reaction. Due to the intensity and magnitude of blast loads, it is important to carry out the most appropriate scheme in terms of economics and safety for a structure. If the design is not done correctly and with the right criteria selected, it may impose exorbitant costs on the execution of a structure. The type of blast in this research is blast in the open air and unrestricted surface. A surface blast is a blast that occurs at a surface or at a very close distance to the ground. In this research, different methods of strengthening the column of concrete bridges under blast load will be investigated. The considered strengthening methods include changing the arrangement of the rebars on the cross-sectional area, increasing the amount of cross-sectional rebars, using FRP rebars and increasing or changing the geometric shape of the column cross-sectional area; Then the most appropriate, economical and safest strengthening scheme is selected and a suitable strengthening model for the above system is presented. The structural models studied in this research are investigated at an identical blast level (1000 kg TNT at 3 meters from the structure). The software used in analyzing the studied models is SAP2000 software. The results showed that some strengthening methods, such as increasing the amount of cross-sectional rebars, increase structural responses. Also, among the strengthening methods selected in the research, replacing FRP rebars instead of regular rebars in the reinforced concrete bridge columns is the most effective and the best method of strengthening these structures against the blast loads.

Critical infrastructures form the foundation and framework of any society, on which the daily activities of societies depend. The operation of these infrastructures is not separate and unique, but they interact with other components and infrastructures of the society. If the performance of one of these infrastructures is disrupted due to natural or man-made threats, in addition to disrupting the continued functioning of that infrastructure, it can also affect the performance of other infrastructures, which leads to disruption of the whole society. To evaluate the resilience of any infrastructure, it is necessary to determine the assets and threats of each infrastructure sector and identify the effective components in the resilience of that infrastructure and then evaluate the resilience of that infrastructure. Gives a weighted pattern using the ANP method To eliminate the ineffective components and to examine the internal relations between the components, the Delphi method and a questionnaire were used. Finally, the components were weighed using the ANP method and Super Decisions software. It should be noted that the underlying threats in this study were determined and examined using the Delphi method and interviews with threat experts. For the first time, the effective components in the resuscitation of road arteries in war crises and man-made attacks were studied and presented in the form of a practical model.

The issue of overflowing domestic sewage with urban industries into water resources, along with population growth and reduction of soil self-remediation, is one of the threats that can lead to irreparable damage to metropolises. The purpose of the current research was to design an integrated management model for passive defense against the threats of drinking water supply chain. This research was based on the objective of a fundamental type and it has used the integrated method. Solutions related to the management of supply chain threats were presented by conducting interviews with experts in the field of water and sewageand then the most important factors were designed in the form of a conceptual model by analyzing the content of the interviews.Following, the effect of each factor on reducing the threats related to the domestic sewage with urban industries was investigated by designing a researcher-made questionnaire and checking its validity through content validity and Cronbach’s alpha test.. For quantitative analysis, structural equation model method, SPSS 26, and PLS 3 softwares were used. The findings showed that modern work tools, prohibitive and mandatory laws, preventive controls and optimal exploitation had a significant positive impact on the threat of domestic sewage with urban industries, while the impact of low-risk measures was not confirmed. The findings of the present research can be used to make strategic decisions in managing and controlling threats related to domestic sewage and urban industries.

Defense architecture is one of the hidden values of historical contexts and passive defense has different criteria based on the type of use and different dangers in historical periods. Today, with the advancement of technology and the change of dangers, the principles of passive defense have also changed, but the initial measures in historical monuments are comparable to the new and modern principles of passive defense. Noshabad Owi Underground Complex, as a 1400-year-old historical site of which only a limited part has been identified so far, is an example of past defense architecture and allows the study of passive defense principles. The purpose of this research is to identify the architectural design in the first part and to analyze the passive defense arrangements in the Owi underground complex in the second part and to investigate how these components are used in the design of architectural elements and its spatial organization. In this article, using descriptive-analytical method and using library resources and field perceptions, while introducing and recognizing the architectural design of this underground complex, the principles of passive defense have been studied and its components and aspects using different sources. Has been extracted and analyzed. The results show that in this underground complex, various techniques and measures in the field of passive defense have been used in the fields of architecture, structures and facilities in accordance with the type of hazards and equipment of the past, and this is the intelligence of the predecessors. It shows us and complete knowledge of the general principles of passive defense from decades ago.

The current research aims to provide an algorithm using artificial intelligence calculations to satisfy all the regulations of Mabhas-6, Mabhas-10, and standard 2800 of the national building regulations while minimizing the weight of the structure. In previous research, the control of constraints and the optimal design of steel moment frames were done in two dimensions and only with older algorithms. One of the most important tasks of this research is the completion of the new restrictions of regulations to control all the restrictions and optimal design of the widely used types of short and intermediate steel structures. All the regulations and controls necessary for the three main types of steel structures widely used in the country, such as 1) braced frames and 2) frames with shear walls, and 3) a dual system of moment frames and shear walls, have been implemented. Finally, the results of this algorithm were validated with a Tabriz hospital project. One of the valuable results of the work is to facilitate the safe design and control process of the steel buildings by providing a graphic panel of the model input and displaying all the essential outputs of the structure in the form of text and diagrams. The work process is intelligently programmed to be performed automatically by just inputting a standard ETABS file into the optimal seismic design process algorithm. In the ETABS file, each design group (e.g., columns, beams, braces, and walls) is defined as a list of usable sections so that the artificial intelligence algorithm can choose the best arrangement. For the three structural examples and the hospital project, we showed that in addition to design safety, significant savings between 11 to 30 percent could be made on the total steel weight, which would take several years to achieve these results for a computer without the use of artificial intelligence.

Examining the thermal behavior of concrete lining of tunnels against thermal loads is of special practical importance. The purpose of this research is to investigate the behavior of fiber concrete lining tunnels with rectangular, semicircular and horseshoe sections under the effect of thermal load in a specific time history. In this regard, numerical simulations have been carried out using Abaqus finite element software. Stress-time and deformation-time graphs in fiber concrete coating under the effect of thermal loads have been investigated. Fiber concrete in this research, which is considered as cover in tunnel sections, is of steel fiber concrete type with a volume percentage of 0.5 to 1.5. Also, in addition to the common design loads, the sections are subjected to thermal loading conditions. According to the obtained results, the strength of the investigated sections depends on the amount of steel fibers in the concrete in addition to the appearance. Investigations show that the cross-section with horseshoe shape has the best performance against thermal load and the increase of fibers up to 1.5 volume percent of concrete compared to tunnel linings with a lower volume percentage of fibers leads to stability in a longer period of time.

Natural disasters and cyber-attacks pose many risks to the acceptable performance of power grids. In addition, the bitter experiences, gained from the recent Natural disasters in the country, lead to a greater focus on the concept of resilience. In this paper, a flexible method for improving the distribution network distribution resilience is proposed considering remote control switches and mobile power sources according to Tavanir Company policies. In the proposed method, changing the network configuration in real-time, controlling switches, and utilizing mobile power sources bring high flexibility and resilience to the network. The objective functions and constraints of the problem are completely linearized to reduce the complexity and solving time of the resilience problem. The mixed-integer linear programming method is used in the proposed method to optimize the objective functions. A modified IEEE 33-bus distribution system is utilized to evaluate the efficiency of the proposed method. According to the results, when the mobile power sources are located in the network based on the proposed method along with sending the repair team and operating switches after a disaster, the value of the objective functions and un-supplied loads are reduced by about 85 %. Therefore, the proposed method has a proper performance in increasing the resilience of distribution systems.

Audio steganography is very important, equally steganography in other media (image, video, etc.). In this paper is presented steganography of audio based on embedded zero-tree waveleten transform algorithm. Improving the resistance against white noise and additive noise with the lowest SNR is one of the important topics in steganography. The proposed algorithm is more robust against normal white noise than uniform noise and has a bit error rate of less than 1 bit against SNRs higher than 10db. According to the obtained BER, if the proposed algorithm is attacked, the hidden signal is lost completel. Also, the proposed method is resistant against additive noise. The proposed algorithm has the least changes in the sound smoothness criterion in frequency domain with Capstrom distance scale and audio files in the form of music with soft tone (loudness), and the increase of secret message does not have much effect on creating disturbances in the frequency domain. The proposed algorithm of the frequency spectrum does not change the audio signal much, and it also follows the property of the hearing threshold level, and high-pitched music with male speech has the best results, so it is favorable to the spectrum structure of Bark. Also, the proposed algorithm has favorable results in the time domain. The lowest SNR is related to high-pitched music with female speech, which has an SNR of about 13db. According to the obtained results, we will have the worst case of embedding a secret message by choosing the audio signal with female speech. Because there is a certain smoothness in the fmale speech signal. Therefore, this uniform state will be lost to some extent by embedding a secret message in this type of audio signal, and the CZD criterion will increase according to the component-by-component comparison of the two main signals and the signal containing the secret message.