فصلنامه پدافند غیرعامل
سال سیزدهم شماره 2 (پیاپی 50، تابستان 1401)

The phenomenon of progressive collapse is very important in the management of structures as well as the discussions related to passive defense. Due to the increasing terrorist threats in recent decades and the prevalence of such issues, this phenomenon has become more pronounced. The soil-structure interaction is also a new science in civil engineering. The structure behavior changes due to interactions with the soil and the literature review reveals various methods that have been presented for modelling this phenomenon in recent years. The main problem of the present study is to determine the critical column in the phenomenon of progressive collapse in steel flexural frame by considering the effect of soil-structure interactions with both the direct and indirect methods. The phenomenon of progressive collapse in the present study has been done with the help of column deletion scenario. In addition, the effect of soil-structure interactions has been modeled using the two direct and indirect methods in both Sap and Plaxis software. The two-dimensional steel frames are made for 5, 10, 15 and 20 story structures and are analyzed by the nonlinear static analysis and examined by the corner and middle column removal scenario. Various parameters such as the coefficient of behavior, base shear, displacement of the operating point and top of the node displacement are removed and the expansion of plastic joints are proposed as evaluation indicators. The results of the present study shows that the corner columns are in a more critical condition and the effect of soil-structure interactions in the direct method is much more significant.

The ultra-high performance concrete which has high ductility and toughness, is widely used in the construction of new structures. The key feature of ultra-high performance concrete is that it has a very high potential in bearing strong loads such as impact loads or explosions. In this paper a 3D model of an ultra-high performance concrete slab is modeled and subjected to blast loading in LS-DYNA finite element software. To this end, different scenarios of blast loading are selected and the responses including the vertical displacement and the plastic strain contour of the slab are determined under each scenario. In this numerical model, the effect of strain rate on the dynamic behavior of materials is also considered. It is observed that when the slab is subjected to a shorter distance and stronger blast load, it first experiences the largest displacement and after that the displacement decreases and remains constant. However, in the case of exposure to a weaker blast load at a longer distance from the surface of the slab, the slab fluctuates relative to the initial position with an almost constant fluctuation period and has little displacements.

One of the important aspects in development planning is paying attention to the vulnerability of the country and cities to the threats of war and natural disasters. Hence, the protection requirements and safety consideration of agricultural-related industries, as the most fundamental food industries in society, are more evident than ever. The present applied research was conducted with the aim of identifying and validating the passive defense evaluation indicators in the establishment of agricultural industries in Kermanshah province by combined (qualitative- quantitative) exploratory method. The statistical population of the study was composed of passive defense experts whose number was determined in the qualitative part with purposeful snowball sampling approach with the theoretical saturation being obtained after 14 interviews. In the first stage namely the quantitative part, using the method of statistical population counting, information was collected from 30 experts. The required data was gathered in the qualitative part through interviewing and in the quantitative part using questionnaires. Data analysis was performed in the qualitative part using open and axial coding and in the quantitative part using spsswin20 and Smart pls3 software. After grouping the obtained codes, 96 markers were identified and then classified in the following 9 categories: 1. spatial compatibility, 2.reinforcements and fortifications, 3.safety, 4.camouflage, deception, concealment and cover, 5. dispersion and downsizing, 6. parallelization of dependent support systems, 7. alarm and warning equipment, 8. crisis management and, 9. education and research. In the second stage namely the quantitative approach, a researcher made questionnaire was prepared in which the content validity was confirmed by professors and the reliability was confirmed by calculating Cronbach's alpha (0/87). In order to perform the validation, the amount of factor coefficients related to each dimension was calculated though the path analysis method and 77 indicators were confirmed. The z factor also showed an effective significance for each one of the 9 dimension indicator paths. The prioritization of each dimension indicator was also confirmed by the Friedman test. Due to the high sensitivity of agricultural industries, for their establishment it is necessary to pay attention to the indicators identified and approved in this research.

Nowadays, the impact of accidents with a low probability of occurrence and severe damage such as natural disasters and terrorist attacks on the power grid has been considered in many research works. According to the reported results, it is highlighted that such events can influence power systems in the form of long-term blackouts in large parts of the power system, the elimination of main equipment (ex. posts, transmission lines, and power plants), and the infliction of severe damage on the equipment. Therefore, the power system resilience concept is defined as the power system capability to reduce the effects that occur as a result of the occurrence of high-impact low-probability events. In other words, the goal of power system resilience is to create a potential capability for accelerating the recovery of the system from the impacts of such events and to adapt its functions and structure to reduce or eliminate the effects of these events. In this paper, a comprehensive review of power system resilience against high-impact low-probability events is provided. The related published works are classified in two parts including resilience against natural disasters and resilience against terrorist attacks. The published work related to each part is described in detail, and the papers of each sub-section are classified from different perspectives and the characteristics of all categories are presented.

As the architectural buildings are among the national investments, their beneficial life should be as long as possible. It seems that ignoring the short life of contemporary buildings is one of the factors that has led to the emergence of complex problems in the economic and environmental fields, the early destruction of contemporary buildings and the massive production of construction debris. Since the arrival of the modern era in Iran, the long working life of the buildings and its necessity has been forgotten, despite the fact that architecture durability has always been at the center of attention in the traditional Iranian society; there are buildings in Iran's historical neighborhoods with the useful life of several hundred years. In this regard, the purpose of this research is to identify the role of materials in the survival of traditional architecture. From the perspective of the research methodology, the research method of this study is qualitative and is a type of grounded theory research, based on the induction procedure and data analysis. By systematically gathering data using library resources, field studies, interviews with traditional architects and applying an inductive analysis, some knowledge about the long useful life of traditional architecture is obtained. According to these studies, considerations related to materials can be considered as one of the factors affecting the durability of traditional Iranian architecture. Knowing how to use the materials, applying domestic materials suitable to the climate, boosting material resistance, matching closely related materials, reducing the material vulnerability against environmental issues, knowledge of material type and finally, choosing materials according to the building functionality are important matters taken into consideration in traditional domestic architecture. Traditional architects had made durable long lasting buildings relying on the collective wisdom and taking into account these considerations and patterns, in general. The patterns that have evolved over the course of history, relying on collective wisdom and have resulted in a durable architecture for Iran.

The present study was conducted with the aim of presenting a passive defense model in the development of sports facilities in Tabriz with a combined approach. This study is practical in terms of purpose, and the research method is the mixed consecutive exploratory type and the collection method is survey. The statistical population in the qualitative sector includes experts in various fields including passive defense, urban management, structures and architecture, as well as experts in the field of sports management. These individuals were purposefully selected for qualitative interviews on the subject of research (17 interviews with 17 people and continued to the point of theoretical saturation). The statistical population of the quantitative section includes the same group of qualitative scratches plus a few more members (as samples). Out of 162 research samples, 128 valid questionnaires were analyzed. The data collection tool in the present study was a semi-structured interview and a researcher-made questionnaire. In the qualitative part, coding and in the quantitative part, structural equation method was used to analyze the data. In the qualitative part of the research, it was found that the categories were extracted in the form of 48 concept codes and 6 main categories. In the quantitative part, it was found that all 6 main categories of research (location, facilities, demographic, human, economic and demographic, respectively) have a good fit, so the research model has a sufficient fit.

One of the most popular ways to detect malware is to find a match for malware file signature pattern in the malware signature database. The malware signature database is pre-extracted and is constantly updated. Checking the similarity of input data using the stored signatures causes storage problems and increases the calculation costs. In addition, the detection based on adapting the malware signature pattern fails when changing the malware code in polymorphic malware. In this paper, by combining the static analysis of executable file structure and the machine learning algorithms, an effective method for malware detection is presented. The data set for training and evaluation of the proposed method includes 36,567 samples of malware and 17295 benign files, and the malware is clustered in 7 families. The results show that the presented method is able to detect and cluster malware from benign files with an accuracy of more than 99% and a false positive rate less than 0.4%. The proposed method has very low processing overheads compared to similar methods and the average scanning time of executable files is 0.244 second.