Aerospace Defense

Abstract Template matching techniques are widely used today in image-based tracking systems to identify and track military targets. Due to their passivity, these systems are resistant to common electronic warfare techniques. One of the problems with using template matching algorithms is that they are slow, especially when rotation and scaling occur in targets relative to a predetermined pattern. In this paper, we perform an optimized algorithm for grayscale template-matching based on correlation coefficients which is invariant to scale and angle. The ‘brute force’ algorithm performs template-matching between the image to analyze and the template query shape rotated by specific angle, translated to specific scale. This takes too long and thus is no practical. The optimized algorithm includes three cascaded filters for scale, angle and template matching which results in probability of scaling, rotated angle for each pixel and point of template-matching, respectively. This algorithm accelerates searching and is 400 times faster than ‘Brute Force’ algorithm. By implementing hardware on the FPGA, it is possible to identify and track military targets at a speed of 10 frames per second.

Abstract Today, terrorism is a serious threat to all societies. The acquisition of nuclear weapons by these groups will pose serious problems for global security. Therefore, studying the methods of passive nuclear defense against nuclear attacks and predicting the direction of radioactive materials can increase the preparedness of society against such attacks and save the lives of many people. Numerous pieces of software have been developed to simulate the release of radioactive material from nuclear weapons and nuclear power plant accidents. The HYSPLIT model is one of the most efficient models in this field. This model has the ability to simulate meteorological with data from different centers. In this research, this model along with meteorological data (GDAS) has been used to simulate the release of radioactive material caused by the explosion of atomic bombs in north of Iran. In this simulation, it is assumed that the atomic cloud resulting from the explosion is composed of 13 particles of different sizes. The results show that the model is well able to simulate the direction of propagation and increasing the size of the bomb will increases the distance of propagation and has no effect on the direction of propagation. Small bomb simulations also give more consistent results.

Abstract Spread spectrum facilitated the using of communication channels. Also it has improved signal privacy against noise jammers and interference. Althogh the privacy of spread spectrum technique is robust against signal jammers and interference with respect to its processing gain , but it can further be improved by side-lobe suppression an and decreasing of side-lobe integration in spread spectrum systems that use match filter for synchronization and despreading of SS receivers .This paper will illustrate a new technique to improve the decrement of side-lobe in comparison with other common related methods such as amplitude weighting.

Abstract In this study, an anlytical exact solution for tow-dimensional steady-state heat transfer in cylindrical sandwich panel made of graphite-epoxy and poly urethane foam is presented. these sandwich panel is cylindrical shape and simulated a ground to air rocket. the symmetry heat transfer in the longitudinal and radial directions is presented. Finding the most possible solution based on complex boundary conditions and parametric studies is one of the innovative aspects of the present study. To find the most complete solution, Matlab and Abaqus software were used. For this purpose, first the cylinder was reliably analyzed in Abaqus software and then using the formulas of Strom-Liouville theory and Fourier transform heat transfer in Matlab software and the results were compared. Finally, the temperature distribution for each composite layer with the desired fiber angle between the temperature distribution for the zero and 90 angles is presented.

Abstract In this article, nickel graphene spinel ferrites are made. The purpose of making these ferrites is to use and examine them as a phase shifting material in the frequency band of 2-18 GHz. First, these materials were made through co-precipitation synthesis method. Then the physical tests of these materials including X-ray diffraction (XRD), infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and histogram of particle size distribution were taken. After that, VNA network tests were taken for these materials. Real and imaginary parameters of dielectric permittivity and real and imaginary parameters of magnetic permeability were obtained after coding in MATLAB software. Dielectric loss tangent and return loss were also obtained for these materials. Finally, the performance of these materials in the hysteresis loop was evaluated using the VSM test. The manufactured ferrite materials showed a good response to magnetic tests in the frequency band of 2 to 18 GHz. The results obtained for the main parameters in line with the studied parameters in radar shifters produced good results.

Abstract In this paper, the design and simulation of a combined navigation guidance law for two-dimensional ground-to-air missile autopilot is presented. In the proposed guidance law, in the missile guidance phase, the proportional navigation guidance method is used for the active guidance system of the ground-to-air defense missile. Since autopilot must be designed to control the path of the missile, we use the linear two-regulator (LQR) method to design the missile autopilot. The design of the closed-loop system is completed using the guidance and autopilot system, as well as the use of a search engine to estimate the range and speed of the missile approaching the target. The simulation results of the designed system show that using the proposed design for the overall control system, the missile was able to track and hit the target at a constant speed.