The study examines the impact of the COVID-19 pandemic on the digital competencies of teachers and the educational achievements of students, focusing on Serbia and comparisons with other countries. For this study, a survey was conducted in three phases, completed by teachers. The time periods during which the surveys were filled out are characteristic because they correspond to specific points in time (June 2019, June 2022, and May 2023). The aim of the first study, conducted in June 2019, was for every school in the Republic of Serbia to explore teachers’ digital competencies as a recommendation of the Ministry of Education. Later, this survey took on a different purpose with the onset of the pandemic. The pandemic exposed challenges such as insufficient teacher preparation for online teaching, educational inequalities affecting students from lower socio-economic backgrounds, and varying levels of adaptability among students. The hypothesis of this research is as follows: Teachers demonstrate a significantly higher level of digital literacy after the crisis caused by the COVID-19 virus than before the crisis. The findings reveal improvements in teachers’ digital skills after the crisis situation, particularly in hardware, software, and internet use, alongside a shift in the primary purpose of digital tools from entertainment to education. The study emphasizes the importance of continuous professional development, standardized e-learning devices, and improved digital infrastructure to enhance the quality of education. The research found that teachers in Serbia showed a significantly higher level of digital competencies after the crisis situation. Key recommendations include integrating digital skills into teacher training, fostering innovative pedagogical practices, and addressing the digital divide to ensure equitable access to education in the future.

This paper presents a class of integer codes that can correct any burst of length \le l within a b-bit byte. Their main advantages lie in linear complexity of encoding and decoding procedures, as well as in the fact that a look-up table-based error control procedure requires relatively small memory resources.

This article presents a class of integer codes that are suitable for use in optical computer networks in which the data are transmitted serially. The presented codes are constructed with the help of a computer and have three desirable properties. First, they use integer and lookup table operations, which make them suitable for software implementation. Second, depending on the application requirements, the proposed codes can be used as low-rate error correction (EC) codes or as high-rate error detection (ED) codes. In the EC mode, which is suited for real-time applications, the receiver can correct all single and double errors, as well as all triple-adjacent (TA) errors within one b-bit byte. On the other hand, if the integrity of data is of high importance, the receiver may operate in the ED mode. In that case, it is able to detect all quadruple errors, all double TA errors within one b-bit byte, and all double TA errors within two b-bit bytes. Finally, it is important to note that the presented codes can be interleaved without delay and without using any additional hardware. Owing to this, it is possible to construct simple codes capable of detecting/correcting multiple TA and random errors.

This paper presents a new method for measurement of power grid frequency based on the use of three complementary strategies: stochastic A/D conversion, finite impulse response filtering and signal frequency estimation using zero-crossing detection. Although such an amalgamated concept offered great flexibility in choice of system parameters, this paper presents the variant with the two-bit A/D converter, which requires the simplest hardware. It is shown that this solution is highly robust against signal distortions, even when harmonic distortion factors have a value of 100%.

This letter presents a class of integer codes capable of correcting single errors. Unlike Hamming codes, the presented codes are constructed with the help of a computer. Among all codes of length up to 4096 bits, a computer search has found four perfect codes: (15, 10), (63, 56), (1023, 1012), and (4095, 4082). In addition, it is shown that, for practical data lengths up to 4096 bits, the proposed codes require only one check bit more compared to Hamming codes.