مجله علوم و فناوری های پدافند نوین
سال پنجم شماره 1 (پیاپی 15، بهار 1393)

Today, the importance of classification of radar object has drastically grown and numerous methods have been applied to achieve this goal. Support Vector Machine (SVM) stands among the newest methods on this subject. Herein, three different types of SVM methods have been suggested for fighter, airplane and helicopter including on-vs-one method, one-vs-rest method and directional acyclic graph method. Since these methods were not sufficiently capable of being distinctive in a linear way, some concepts of Kernel function such as polynomial, linear, quadratic and basic radial function have been used. Directional acyclic graph method using Kernel function yielded the best results according to the outputs obtained from simulation. One-vs-rest method using RBF and quadratic Kernel as well, was more adapted than on-vs-one method. The run time of performing these three methods is also deeply verified. The results showed a similar run time for all the three. Hence, to classify the noted goal, the method of directional acyclic graph is proposed as it manifests the most optimized performance in terms of accuracy.

A proper camouflage pattern for military forces has an important role in success of military operations. Visual evaluation often is used for selecting the most proper camouflage pattern. The visual methods are not efficient, because they are depending on the accuracy and expertise of observers, and also inconsistency between experts opinion. Therefore, an efficient scientific method is necessary. Based on the literature review, two important criteria were found based on background matching and disruptive coloration. Beacause of the dependency between these criteria, a method based on analytic network process (ANP),which is more accurate than visual methods, has been presented. Also, a heuristic calculating process for this ANP-based method, has been used instead of SUPER DECISION software. The proposed calculating process afforded the results in much easier way with the same accuracy, without using the relevant software.

According to the importance of control and dispatching centers and their critical role in the control and management of the power plants and transmission networks, construction of the dispatching centers based on the security and technical standards is vital for power systems. Existing buildings of dispatching centers are relatively old, and security standards and requirements to deal with the natural disasters and enemy attacks are not met, and also, technical standards for potential development of these centers are not considered. In this paper a method is proposed which be used to develop and reconstruct the existing control centers or new buildings. First, a comprehensive optimal location criterion is required in such a way that it could be able to cover all the scientific, technical and experimental aspects. The most important criteria include passive defence consideration, natural and unnatural disasters, civil, economic, technical performance and welfare of employees. Here in, a method is proposed to find the optimum location of dispatching control centers considering several criteria through a multi-criteria decision-making (MCDM) method. The method combines an AHP and entropy techniques (EAHP).

In this paper, first, the principles of physical modeling in geotechnical centrifuge has been explained and then, the application of these principles in modeling of the blast loading is described. Thereafter, procedures and equipment of a blast test in IUST centrifuge are described. Results are presented in the form of acceleration, stress and strain time histories for two different points of underground structures that is located in the depth of 5.6 meters from ground surface. It is observed that the results are in good agreement with existing codes and past researches. The results of this study can be used to investigate the effects of blast loading on underground structures and verification of softwares to more extensive studies.

The blast loadings lead to serious damages in structures so that designers try to reduce these effects by special methods. In comparison with other threats such as earthquake and wind, the blast load has some unique characteristics i.e. the applied pressure to the structure, the situation of the blast source and small duration of blast loading. In this paper, a new approach is proposed for controlling the structural vibrations arising from the blast loads. The proposed active control method is based on structural dynamics theories in which multi actuators and sensors are utilized. Each actuator force ismodeled as an equivalent viscous damper so that several lower vibration modes are damped critically. This subject is achieved by simple mathematical formulation. The proposed method does not depend on the type of dynamic load and it could be applied to control structures with multiple degrees of freedom. For numerical verification of proposed method, several criterions such as maximum displacement, maximum kinetic energy and maximum drift are evaluated in a five story shear building, subjected to the blast load. The results show that the proposed method has suitable efficiency for reducing structural vibrations caused from blast loading.

Any country's vital infrastructure, including transportation, plays a major role in a disaster situation. As transportation networks are threatened by different events such as natural disasters (e.g., earthquakes) and also man-made disasters (e.g., terrorism).Therefore, the identification, protection, stability, and development of transportation infrastructure is a vital issue during a disaster. In this paper, a spatial decision support tool, termed ISRT, is proposed. By using this tool, the road transportation network performance is evaluated based on four criteria, i.e., capacity of the roads, accessibility of the roads to military locations, vulnerability of the roads and the importance of the roads in the geometric structure of the network. By proposing the concept of strategic roads, the road networks, studied in this paper, are ranked. The tool is able to interact with decision-makers, receive their priorities and show the results on a map. The results indicate that eight percent of the roads under study are strategic.

In this study, the effects of tunnel cross-section geometry and relative position of the explosives on the performance of the lining structure subjected to external blast loading have been investigated using finite difference method. The crosssection geometry of the modeled tunnels considered as rectangular, horseshoe and semicircle and designed based on the regulation proposed in the Iranian code No. 161(Geometric Design of Roads). To evaluate the effect of the explosive relative distance, the blast center on the ground surface was assumed at different distances relative to the center of tunnel crown. The results indicated that under the surface blast, the performance of the horseshoe crosssection tunnels was more suitable than the others. Furthermore, for the all cross-section types, the increase of blast center distance relative to the center of tunnel crown resulted in a reduction in the maximum vertical displacement of the center of tunnel crown. This was observed together with an initial increase and then reduction in the maximum values of axial force, bending moment and normal stress in the lining of tunnels.

In this work, a novel method for trace detection of uranium (VI) in water samples isintroduced. The method involves two-steps: selective preconcentration of uranium (VI) using amine functionalized nanoporous silica and reaction of uranium (VI) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) to reach a colorful complex. The effect of various parameters on preconcentration and formation of uranium (VI) complex were studied and optimized. The effect of some metal ions interferences such as Cu (II), Fe (II), Zn (II), Ni (II), Pb (II), Th (IV) and Cd (II) with the concentrations of 50 ppm reveal that these ions (except for Cu(II)), does not have any interference in this method. The detection limit of the method was obtained as 0.02 ppm. This concentration is appropriate for developing the eye sensing technique for trace detection of uranium (VI) ions. The method was successfully applied for trace detection of uranium (VI) in tap, sea and well water samples.