فصلنامه پدافند غیرعامل
سال یازدهم شماره 1 (پیاپی 41، بهار 1399)

Steganography on the VoIP Platform is a Real-time network Steganography Method, It uses VoIP Protocols as a cover channel to hide messages. At the moment, real-time steganography is one of the challenging research areas. The reason for this is the inherent characteristics of the transfer of information in real time, which limits the complexity of operations. In this paper, we first describe the definition of Steganography and describe the VoIP concept briefly, and then we will describe some of the work done in this field. In continuation, we express the way VoIP works and the problems that we face, and then we consider the concept of VoIP Steganography and describe its challenges. Finally, introduce some of the most widely used methods of VoIP Steganography, and then we compare the different ways of VoIP steganography with each other, and discuss the weaknesses and strengths of each of them. In the final section of this paper, we will give the research results.

Earthquake is one of the eminent dangers that threaten the lives of people in Tehran. Therefore, the urban management administration should make the best decisions for prevention and safeguard measures after the occurrence of this natural event. Due to the psychological effects of the crisis time in the managers' decision-making, necessarily a mechanism independent of the crisis effects should be designed that analyzes the urban situation and provides crisis management proposals. Tehran consists of 22 zones that are located on 13 faults. Hence in this paper we design and present an expert system which uses process pattern and takes important physical and urban concepts indices, as well as the factors that are identified by the Center for Vibration Detection as input, and offers the necessary plan to take appropriate measures relating to each of the 22 zones’ safety centers in Tehran. This plan offers the best actions for each region in the event of an earthquake, according to the indicators of the region. The purpose of this paper is making crisis management smart in order to minimize damage in the event of an earthquake. Finally, to evaluate and compare the proposed method with Mercalli and Richter methods, the occurrence of a hypothetical earthquake in Ozgol area of region number 1 of Tehran was assumed, and a program preview implemented. The results show that the method presented in this article is more precise than Richter and Mercalli methods in proposing the provisional measures for the mentioned earthquake, due to the effectiveness of various factors in this method.

The earthquake is one of the coincidental events with fault that at the time of the event, this phenomenon can cause damages to vital facilities such as roads, railway, oil and gas pipe lines and buried electric cables, tunnels and Buildings. The occurrence of frequent earthquake in Iran, indicates the existence of tectonics activity in the present century. Seismicity assessment is a preliminary measure for estimating the risk of earthquakes in the region or their existing structure. In this study, seismicity parameters of the study area were studied using Zmap software, which is a set of Matlab software codes. The study area is located in the northwest of Iran, in the East Azerbaijan 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. In this study, the earthquake recurrence time and annual probability were calculated and zonation maps were prepared based on the b-value and Mmax rate. By examining the b-value zoning map, the dominate value of this coefficient is found to be between 1.17 to 1.38 which is about 33.12% of the total area and the study path is located in this area. Minimum and maximum Mmax values are 3.5 and 5.4 Richter respectively, the path studied being in the range of 4.4 to 4.5 Richter. Finally, it can be concluded that the study area is susceptible to the possibility of major earthquake, and the necessary measures for the stability and prevention for the destruction of existing structures should be considered.

In crisis situations, such as natural disasters and warfare, using inactive means, it is possible to prevent financial losses to vital and military installations and human casualties, or to reduce the amount of such damage and losses to the minimum. Given the importance of health care centers, hospitals are one of these critical areas and the need for the facility to make non-operational defense strategies is essential. This study was to investigate the readiness of Tehran hospitals for passive defense in 1397. This cross-sectional descriptive study was conducted on 15 managers of hospitals in Tehran. The sampling method was census method and the data gathering tool was a researcher-made four-part questionnaire.Data analysis was performed using SPSS23 softwares and descriptive-analytic tests of Spearman correlation, univariate regression and t-test. Knowledge of physical characteristics 0.71, dispersion of 0.606, multiple outputs 0.587, open space, 0.518 The highest level of knowledge and awareness of shelter 0.138, depth and height of building 0.018, aerial access 0.016 showed the lowest level of awareness. The readiness of hospitals in Tehran was moderately low.

New developments in the field of science, technology, politics, and military have caused the attention of various countries to the field of new war and In particular, the development of new factors and methods of attack on the underlying targets to damage them. In this context, UAVs with regard to their kind, facilities, and equipment are able to perform a variety of intelligence missions including identification, surveillance and targeting and electronic intelligence by priority optimal use of facilities, especially human resources. In other words, UAVs are among the advanced equipment of current era that will have a special place in future wars that will be asymmetric and heterogeneous. Hence, in this article we have tried to comprehensive introduction of UAVs, Identification of influential indicators on UAV intelligence missions. In this way, we weighted and prioritized the indicators using the opinions of military experts and Fuzzy Analytical Hierarchy Process (FAHP) method. The results of the present study indicates the identification Criterion is the most Influential criterion in promoting the UAVs mission and visibility UAV cameras is the most important sub-criteria affecting on identification criteria on information UAVs in the future asymmetric wars.

At recent years, online social network sites have been popular dramatically. Cybercrimes use from social media as a new platform at acceptation of some types of computer crimes like phishing, spamming, malware spread and cyber harassment. In this research, we will improve the function of detecting cybercrime with the help of useful information in the messages. Choosing the best features with high separation. Strength between cyber harassment tweets and none cyber harassment is a complex activity which extremely needs substantially effort in making Machine Learning Model. In this way, we compare function of five classification methods Naive Bayes, Support Vector Machine, Decision Tree, k-Nearest Neighbor and Neural Network under five different tuning in order to selecting the best adjustment for suggested features. Also, we have improved C and Sigma parameters by using the bat, genetics and particle swarm algorithms. Additionally, we have compared five classification methods with default parameters and parameters obtained with optimization algorithms. Finally, we have shown that bat algorithm has had the best performance among other optimization algorithms. According to the research we did the most accuracy with the SVM model to 86.56 and the highest precision to 87.14.

One of the passive defense policies in any country is site selection for public shelters in order to prevent casualties and protect the lives of citizens, and to strengthen the spirit of defense and reduce vulnerabilities in the human domain, which considering the increasing threats of the enemies of Islamic Republic of Iran, should be one of the requirements on the agenda of urban decision makers. In addition to the increasing urban population, thanks to the presence of Hazrat Abdolazim, Shahre-Rey hosts thousands of pilgrims. Considering the overcrowding of residents during the pilgrimage days, the necessity and importance of controlling the traffic and the readiness to direct the people to public shelters in the holy shrine are becoming increasingly apparent. Therefore, by implementing the principles of site selection and locating and designing dual purpose public shelters in the Hazrat Abdolazim holy shrine before the crisis, the severity of the casualties and damage caused by the enemy's aggression in a critical stage can be greatly reduced.In this research, based on library and documentary studies, the criteria and indicators for dual-purpose public shelters site selection in the shrine complex were identified and interviews and questionnaires from experts and field visits and SPSS software were used. Considerations and principles of dual-purpose public shelters site selection were extracted and prepared in the Hazrat Abdolazim holy shrine, and according to these principles, suitable places for the construction of shelter were specified in AutoCAD by staining. The achievements of this research are dual-purpose public shelters site selection in the Hazrat Abdolazim holy shrine and updating technical and theoretical knowledge about the effectiveness of using common principles of passive defense in the site selection of dual-purpose public shelters.

Today, the growth of threats and military weapons and the rise of terrorist attacks has pushed governments into a comprehensive plan of non-operational defense in order to increase their security. Underground structures are one of the most basic ways to protect sensitive and strategic sites against explotions.In this paper, the dynamic interaction of soil and structure is considered, and at this stage, the results of nonlinear dynamic analysis are compared with the results of experimental and analytical relations. Also, while considering the behavior of the buried structure under the influence of the explosion load, the effect of different parameters, such as structural depth and position of the explosion point relative to the structure, and the dynamics characteristics of the complex in the type of structural performance, have been investigated.Then, in the last part, according to the results obtained from the previous section, it was proposed to conclude and provide solutions for protecting and retrofitting the buried structures against the explosion. Finally, it has been observed that the protective concrete layer alone was not effective for the reinforcement of the underground structure due to direct transfer of soil to the soil, and its composition with a porous medium such as a protective concrete box on a structure with porous space is close to 100% Attention was paid to reducing the pressure on the underground structure.