نشریه دفاع هوافضایی
سال دوم شماره 3 (پیاپی 7، پاییز 1402)

In this article, a contrast enhancement algorithm using wavelet transform is proposed to create natural enhancement in images with various brightness ranges. In the proposed method, the input image is first decomposed into 4 sub-bands by discrete wavelet transformation. Then, in the LL sub band image, the histogram cutting process is performed by the cutting threshold level equal to the average intensities. Next, the cut histogram based on entropy is divided into three parts with approximately equal number of pixels, and before equalization process, each sub-histogram is mapped to the new dynamic range. Finally, we use the inverse discrete wavelet transform to create an improved image. By controlling the enhancement ratio, the proposed method produces an image with maximum details and natural enhancement in the output image. Comparing the performance of the proposed method with previously presented methods, in terms of entropy as well as visual quality based on the mean opinion score, shows the superiority of the proposed algorithm.

The Kalman filter is a set of mathematical equations that is a computationally efficient tool for estimation. It provides us with the process status, in this way, it minimizes the mean square error. In some applications, this filter is very strong, it supports the past situation as well as the present and future situation. This mode is accurate for when the system model is also uncertain. The Kalman filter guides general problems trying to estimate the state x so that the discrete-time process is linearly controlled by a stochastic differential equation. The purpose of this article is to correctly track the target used in a radar with the help of the Kalman filter technique and MATLAB. The result of the implementation has been analyzed and planned for flight system maneuvers using a simulated target.

As radar technology advances, training operators to effectively analyze and respond to potential threats is critical. This research presents a PPI radar display simulator implemented using C# and WPF platform. This simulator integrates a neural network powered by the Encog library with a radar display to predict attack locations and future trajectories of simulated targets. The implemented neural network has a four-layer architecture that allows operators to adjust multiple network parameters to suit their needs. With the ability to change training data through Excel files, this simulator has increased interaction with the user, and it is also possible to add or remove target locations. This allows for more realistic scenarios. The implemented simulator allows the operators of Khatam al-Anbia Air Defense University to strengthen their skills in radar data analysis and familiarize themselves with a comprehensive and advanced learning environment of new generation radar displays equipped with neural network technology.

In this paper, the effect of impurity injection on the structural, optical and magnetic properties of ZnO nanostructures prepared by sol-gel method was investigated. The Ultraviolet spectroscopy (UV-Vis), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and vibrometer magnetometer (VSM) were used to analyze the samples. The experimental results showed that the addition of impurities caused the displacement of the adsorption peak and the reduction of the band gap. From the XRD spectrum, it appears that all specimens are formed in the Versatite structure. No additional peaks are seen in the spectrum, indicating complete phase formation without creating any secondary phases. The absence of additional peaks indicates the high solubility of iron in oxidation, and the results show that the addition of impurities increased the size of the nanocrystals, while the increase in the percentage of impurities did not affect the size of the nanocrystals. Also, iron impurity has caused ferromagnetic properties in the samples so that with increasing the amount of impurity, the induction field decreases. Ultraviolet spectroscopy (UV-Vis), scanning electron microscopy (SEM) and vibrometer magnetometer (VSM) were used to analyze the samples.

In this study, the numerical investigation of the pre-approved connections of the 10th topic of the National Building Regulations under explosive loading was done. For this purpose, six three-story, two-span frames with different connections were examined. These frames had similar beams and columns, and their connection types differed. The results showed that the frame with a bolted unstiffened extended end-plate connection (BUEEP) had the minimum displacement and optimal performance under explosive loading. Also, the frame with the reduced beam section connection (RBS) had the highest displacement and the weakest performance. Decreasing or increasing the number of floors did not affect the optimal performance of the frame with a bolted unstiffened extended end-plate (BUEEP) connection. To improve the performance of these connections, various methods were investigated. It was found that adding a steel plate with a thickness of 1 cm to the center of the column and the two ends of the beams separately reduced the maximum displacement of the frame by 11 and 5%. Meanwhile, adding a steel plate with a thickness of 1 cm to the two ends of the beams and the middle of the column at the same time caused a 15% reduction in displacement at the level of the third roof of the frame, which is a very suitable method to improve the performance of connections against explosion.

Summary: Gamma rays, like radio waves, infrared waves, ultraviolet rays, and X-rays, are a type of electromagnetic waves. The beginning of the use of radiation dates back to the end of the 19th century, after the discovery of X-rays by Rothengen. The use of radiation is widely and successfully seen in medicine, industry, agriculture and research sectors. For example, neutrons and gamma rays are used in medicine to treat cancerous tumors, and X-rays are used in radiology. In the defense and military industry, gamma rays emitted from radioactive radium and cobalt with high power. They are used to find small holes and fractures of metal parts in the aircraft and missile industry They are also used to determine the type and amount of radioactive material in aerial monitoring of gamma rays during identification operations. Another application of rays in the field of radiation processing. Ultra-processing is used in order to process and modify materials, reduce harmful industrial waste and reprocess waste water, etc., which is introduced in more detail in the rest of this article. Therefore, in this article, radiation and its types are first explained, and then the different types of gamma radiation systems are introduced, as well as some radiation emitters in the world are discussed.