نشریه دفاع هوافضایی
سال دوم شماره 4 (پیاپی 8، زمستان 1402)

Software testing operations, as one of the fundamental methods for evaluating the quality of software products, are employed throughout various stages of software development and maintenance. With the increasing complexity and ubiquity of software, the need for performance and efficiency testing methods with a suitable balance between reducing time and increasing accuracy is felt. In this study, automated software testing methods using Biogeography-Based Optimization algorithms, coupled with the bat algorithm, have been investigated, resulting in the production of a high-performance covering array. These innovations, along with the utilization of optimized data structures, have not only aided in managing software complexity but also addressed the success requirements of software projects. This research is recommended for enhancing the quality of software products, focusing on producing covering arrays with high efficiency and improving the performance of software testing.

In this work, an attempt was made to prepare thin layers of nanostructured cadmium selenide (CdSe) based on a simple solution method of chemical bath deposition (CBD), which commercially has an accessible precursor. In the chemical solution bath layering method, manufacturing factors play a significant role and determine the characteristics of the final product. In this research, the effect of an important factor, the concentration of primary solutions of selenium and cadmium ions, which is one of the most important factors in the formation of cadmium selenide, and it will be observed that the change in the concentration of these metal and non-metal ions strongly affects the type of electronic structure of the material. In comparison with the sputtering methods, in the chemical solution deposition method, there is a high control in the formation of solid deposits with different combinations of metal and non-metal binary compounds. Changing the selenide ionconcentration changes the size of the energy band gap. It has been observed that the energy gap increases with the increase of selenide non-metal ion concentration.

This article aims at the improvement of Synthetic Aperture Radar (SAR) resolution by using a Matched Filter (MF) based on the Fractional Fourier Transform (FrFT) that has been called a Matched Slope Filter (MSF). Generally, the received SAR signals are processed by well-known algorithms to extract the final image, such as the Chirp Scaling Algorithm (CSA) and the Range Doppler Algorithm (RDA). Implementing a Matched Filter (MF) that aims at compressing the received signal in the range and azimuth directions is a principal part of these algorithms to deliver target positioning and high resolution. Because the transmitted signal by SARs has often been Linear Frequency Modulated (LFM), the received echo from the targets in the range direction is the LFM. On the other hand, there is always a chirp signal in the azimuth orientation. Thus, this paper proposes the Matched on Slope Filter to improve the compression of the azimuth signals. It's clear the proposed method has been adopted for LFM signal compression in the range direction also. The evaluation results show that our method that uses the FrFT in the time-frequency domain for implementing a Matched Slope Filter enhances the resultant azimuth resolution and reduces the sidelobe level compared to the other frequency-based method.

In this paper, a rotor position estimation algorithm based on sliding mode observer (SMO) and phase-locked loop (PLL) for permanent magnet synchronous motor (PMSM) control in STM32L431RCT6 microcontroller is presented. The proposed SMO and PLL-based observer has two advantages compared to the conventional SMO observer: reducing the undesirable phenomenon of chattering and improving the accuracy of rotor position estimation. In this research, a hybrid sensorless control system for PMSM drive has been designed, using the I-f startup method and a smooth transition to sensorless closed-loop vector control with SMO and PLL. C programming language is used to implement field vector control, phase-locked loop, sliding mode observer, proportional-integral controllers, space vector pulse width modulation, and coordinate transformations. The proposed method is implemented using STM32 family 32-bit microcontrollers. In the following, the presented laboratory results show the desirable performance of the proposed observer.