Advanced Defense Science and Technology
Year:2020 | Volume:11 | Issue:1|Papers Count:10

The efforts for better planning of power systems from various viewpoints, such as economic, technical, and environmental, for reliably meeting the demand are continued. The unit commitment (UC) is one of these planning problems. In this paper, the security-constrained unit commitment problem is addressed with focusing on the strategic importance of electrical energy in the presence of smart grids. To achieve this, firstly, a comprehensive UC model, amalgamating with emergency demand response programs (EDRP), is presented. To adapt the model with war condition, a modified form of EDRP, the so called strategic EDRP, is also proposed. The problem is formulated as a mixed integer linear programming problem solved via the GAMS. Then, to investigate the impacts of smart demand response programs on the reliability of load meeting, several scenarios are conducted regarding a stochastic contingency model for generating units under war condition. It is found in result evaluation that smart demand side contribution under war condition can increase reliability and so decreases the costs.

Today, the attacks on the infrastructures of the electricity industry by Graphite bomb are very likely. By securing the power grid, the damages can be minimized. One of the ways that can be implemented in Iran's power grid is the reconfiguration of the distribution network. Reconfiguration is actually a change in distribution network arrangement by changing the state of the normally open and normally close switches. In this paper, the reconfiguration of the distribution network is used to reduce the possibility of blackout in sensitive areas of the military sites during a Graphite bomb attacks. The used optimization algorithm, is the discrete particle swarm algorithm and the network under study, is the 69-buses IEEE network. The results show that reconfiguration can significantly reduce the possibility of blackout and damage to military areas during Graphite bomb attacks.

The wide spreading restructuring has laid further emphasis on economic and reliable operation of power grids. Power systems are, however, always subject to disturbances. These disturbances cause an unbalance between the electrical and mechanical power in generators, thus leading to angle oscillations on generator rotors. The analysis of system behavior in case of large disturbances is referred to as transient stability. On the other hand, exploiting renewable sources has been increasing due to the ever-increasing energy requirements in the developing and developed countries. Solar power is among the main sources of renewables that has drawn much attention due to the environmental concerns. In this project, the impact of integration of photovoltaic (PV) systems on transient stability of bulk power systems is investigated. As the PVs have different dynamic characteristic than the synchronous machines, system dynamic behavior will be affected by an increased penetration of photovoltaic generation. An appropriate model is, therefore, utilized for PVs in the transient period and incorporated in the energy margin. The sensitivity of energy margin is then calculated to the replacement of conventional generation resources with photovoltaic resources. Based on different scenarios, for example, four faults in the power system, the photovoltaic generations are located and sized at various buses.

The Security of Power networks is one of the main focuses of operation utilities and measuring parameters of lines, buses, and other substantial equipment has particular importance for them. Essential role of measuring and control in normal operation of smart grids makes cyber security an important necessity for todays and future power grids. Therefore, as the power network depends on communication systems and information technologies, using phasor measurement units (PMUs) in order to measuring, protection and control become expanded. Reconfiguration of the power network is implemented for several reasons including loss reduction, improving voltage profile, power quality, etc. In this paper power network observability through PMUs which are allocated optimally is analyzed in reconfigured networks in order to investigate the network cyber security. Performance of the proposed method is evaluated in 14-bus and 30-bus IEEE.

The importance and demand of visual scene understanding have been increasing because of autonomous systems development. Optical flow is known as an important tool for scene understanding. Current optical flow methods present general assumptions and spatial homogeneous for spatial structure of flow. In fact, the optical flow in an image depends on object class and the type of object movement. The first assumption in many methods in this field is the brightness constancy during movements of pixels between frames. This assumption is proven to be inaccurate in general. In this paper, we use recent development of deep convolutional networks in semantic segmentation of static scenes to divide an image in to different objects and also depends on type of the object different movement patterns are defined. Next, estimation of the optical flow is performed by using deep neural network for initial image which has been semantically segmented. The proposed method provides minimum error in optical flow measures for KITTI-2015 database and results in more accurate segmentation compared to state-of-the-art methods for several natural videos.

The reflex triode is one of the varieties of vircators that are among several types of high power microwave sources. The Main application of these tubes is the disruption of enemy systems by creating a strong electromagnetic field on the target. This paper presents a comparison of experimental and simulation results of a reflex triode. Experimental and simulation results are in good agreement. The software used for simulation is the CST STUDIO SUITE. It is based on the Finite Integration Technique (FIT) and includes a particle in cell code. In previous studies, with the use of two disk-shaped and strip reflectors in this tube, the electric field output was increased by a maximum of 126%. In this research for the first time with the introduction and use of wall reflector, the electric field output was increased by 193%. It was shown that each of the disk-shaped, strip, and wall reflectors increased 37% and 29% of the output electric field, respectively. A variation in the position of the reflector causes a variation in the radiation power. This variation is periodic.

Using the high-speed data communication systems, along with the quality of service desirable, is the infrastructure of a command and control system (C41) that should be used in the worst case scenario with the best transmission quality. The use of such a structure in the new defensive systems is very important research topics. As bandwidth increase to increase data rates is costly and sometimes impractical, the use of the orthogonal frequency division multiplexing systems (MIMO-OFDM) The main technology has become the 4G systems. Because of this, multi-channel systems in wireless systems are used to improve the transmission quality and high-speed telecommunication data, and recently, Frequency-Time-Space Coding (STF) methods have been developed to improve multiplicity interest. The purpose of this paper is to analyze the MIMO-OFDM using a combination of beam shaping and STF techniques. The proposed STFBF method, which combines these two methods, performs better in terms of bit error rates than STF without beamforming and the proposed model is better than the combination of beamforming method and time-space block method (STBC).

In this paper, the explosion wave effect on prestressed concrete shells was numerically discussed. For this purpose, at first, a semi cylindrical shell roof without pre-stressing imposed by an explosion of a ton of TNT at a distance of 10 meters from the center line of the structure. The finite element analysis was performed by Abaqus software and the results of tensile and compression failures are extracted and verified by the results of the literature. In order to investigate the effect of pre-stressed tendons in longitudinal direction on mises stresses and tensile and compression failures, the semi cylinders were pre-stressed by 3 MPa, 5 MPa and 8 MPa. In addition, the effect of the span length on the results of mises stresses and failure modes was evaluated using three lengths of 30, 45 and 60 meters. The results of the analysis showed that the pre-stressed structures would reduce the damage caused by the explosion. Increasing the span length causes the failure to focus on longitudinal symmetrical axes.

Coding theory is one of the most interesting and applied branches of mathematics that has been widely used in Wireless networking, include mobile networks, wireless local area networks, wireless sensor networks and satellite communication networks. In this paper, our goal is to provide some new codes by using t-Pell number sequences and Hadamard product. In order to achieve this goal, we first study the properties of matrix of t-Pell number sequences and their Hadamard product of these matrices. Then, using the obtained results, we present some coding and decoding algorithms. Finally, we study the blocking algorithm on the matrix of the t-Pell number sequences and their Hadamard product.

Researchers have always been interested in graph nodes clustering based on content or structure. But less attention has been paid to clustering based on both structure and content. But a content-structural clustering is needed in information networks like social networks. In this paper, the ICS-Cluster algorithm is proposed which takes into consideration both the structure and content aspects of the nodes. The purpose of this approach is to gain a coherent internal structure (structural aspect) and homogeneous attribute values (content aspect) in the graph. In this approach firstly the graph is converted into a content-structural graph which edges' weight show similarity between the connected nodes. Incremental clustering is done based on edges’ weight in this process the edges with the most weight is considered as clusters then the weight of connected edge to the cluster is aggregated and they’ ll be one edge, the process is repeated until the algorithm reaches the number of clusters that indicated by the user. ICS-Cluster algorithm number of cluster is indicated by the user. Comparing ICS-Cluster with other content structural algorithm based on six criteria for measuring cluster quality shows that ICS-Cluster has good performance. These criteria contain structural criteria (Modularity, Error Link, and Density), content criterion (Average Similarity), content-structural criterion (CS-Measure) and the run time.