Majlesi Journal of Telecommunication Devices
Volume:11 Issue: 4, Dec 2022

With the advent of communication networks, the speed of data transmission has increased dramatically. One of the important factors in each transfer is to maintain data security and prevent unauthorized access to data transmitted. Using cryptography is one of the methods used to keep data secure throughout the transmission path. Today, with the growth of computer networks, the use of video conferencing, the transfer of military information, image data, the need for encryption of data in a variety of image data plays an important role. Encryption in images due to its specific features, such as the high volume of transmitted images, the amount of additional data for encryption, the correlation coefficient and the high repetition among the pixels, are very different from the text data; this has led to all traditional encryption methods It is not suitable for image data and there are changes in their structure to use traditional methods in image cryptography. In this paper, using pixel shift algorithms and Hill's encryption algorithm, ciphering of color images has been addressed; the pixel shift algorithm has been used to maintain greater dependency and security, and Hill's encryption algorithm has been used to change the amount of pixels. For analysis of the work, the algorithm is presented and for comparison with other methods, images and standard analysis methods have been used. The obtained results improve the efficiency of the proposed algorithm in comparison with the standard hail algorithm (especially in images with similar pixels) And compared with other comparable algorithms.

The continuous progress of photography technologies as well as the increase in the number of images and their applications requires the emergence of new algorithms with new and different capabilities. Among the various processes on medical images, the segmentation of medical images has a special place and has always been considered and investigated as one of the important issues in the processing of medical images. Based on this, in this research, a solution to diagnose the tumor through the use of a combined method based on watershed algorithm, co-occurrence matrix and neural networks has been presented, so that through the use of this combined solution, the tumor can be detected with high accuracy. Medical images diagnosed. According to the method used in this research, as well as the implementation of the solution in the Python environment and through the use of CV2 and SimpleITK modules, it is possible to set parameters such as accuracy, correctness, recall and Fscore criteria. which are always important parameters that are investigated in researches, improved compared to the past and achieved favorable results. This will increase the improvement of tumor detection in the brain compared to Thersholding and TKMeans methods.

The purpose of this study is to determine the optimum location for intermediate band in the middle of band gap of an ideal solar cell for maximum performance. By changing the location of the intermediate band, output current and therefore performance can be changed. Choosing the best location in terms of solar cell energy gap and how to change the performance by means of the location of intermediate band has the important role in the energy band gap engineering. This matter in the known methods of the intermediate bands realization such as quantum well and quantum dots can be used for selecting the type of semiconductor in quantum well or quantum dot and also for selecting dimension of quantum dot or quantum well. Conclusion of this paper is by increasing energy gap, the optimal location of intermediate band for cells with one intermediate band, will be closer to the middle of the energy gap.

Block chain technology, known by popular crypto currencies mainly Bitcoin, is widely used in several fields, not only in the financial sector but also in the healthcare industry as well as supply chain management sectors. To produce an efficient block chain, consensus algorithms are an essential part of it. Proof of Work (POW) and Proof of Stake (POS) protocols are widely used in many block chain networks such as Bitcoin, Ethereum, and Litecoin. Block size optimization solves the trade-off between maximum revenue and becomes an alternative payment system. In this research, differential evolution algorithm was used to determine the size of the blocks. The simulation of this research has been done in MATLAB environment. In order to evaluate the proposed method, two scenarios of the number of miners and the type of request have been used. In this research, statistical criteria have been used to evaluate the proposed method. The criteria used in this research include maximum, minimum, average and standard deviation criteria. The results showed that in the scenario of the number of miners, the best answer was obtained in the case where the number of miners was equal to 3. In the request type scenario, the dependency of the requests has been checked. In this case, requests are considered dependent and non-dependent. The results showed that in the non-dependency mode, the request processing time has decreased because in this mode the requests can be executed simultaneously with each othe. in the dependency mode, the requests have priority over each other.  In this case until the desired request is not executed, the next request cannot be executed.

High output power, good efficiency, sufficient power gain, compact size, and low cost are essential parameters of high-frequency integrated microwave power amplifiers. Due to its unique characteristics, gallium nitride is considered a good choice for realizing high-frequency power amplifiers. This article presents an integrated microwave power amplifier with high efficiency and wide bandwidth in 0.25 μm GaN technology. Input and output matching networks are realized using spiral inductors, on-chip resistors, on-chip capacitors, and appropriate transmission line structures. The optimal values of the elements have been determined using the random and hybrid optimizer in the ADS simulator. Large on-chip inductors in the drain and gate bias circuits were used for biasing. They were designed in such a way that no ac signal leaks into the bias circuit. The proposed circuit works at 6.8 GHz to 11 GHz frequency, while its maximum PAE is 60%. The small signal gain at the frequency of 9.8 GHz is 12.45 dB, whereas the saturated output power is 32.68 dBm.

Networks are all around us and can be in the Euclidean space of concrete objects such as power grids, the Internet, highways or subway systems, and neural networks, or in an abstractly defined space, such as networks of familiarity or cooperation between people. To express the general properties of such networks, their modeling is in the form of graphs that show the nodes as oscillators (the dynamic unit) and the edges as the existence of interaction between oscillators We applied the Kuramato model to networks of oscillators connected in a small-world network pattern and considered the influence of oscillators on each other as conformist and contrarian. Based on this, we examined the synchronization in the network. We showed that if the number of contrarian oscillators in the network reaches a certain value, it will cause more of the network, which is due to the weakening of defects created in compatible oscillators.