Studia Informatica. System and information technology <p><strong>ISSN:</strong> 1731-2264</p> <p><strong>DOI:</strong> 10.34739</p> <p><strong>Points:</strong> 40</p> Wydawnictwo Naukowe UPH en-US Studia Informatica. System and information technology 1731-2264 K-means is probabilistically poor <p>Kleinberg introduced the concept of k-richness as a requirement for an algorithm to be a clustering algorithm. The most popular algorithm k means dos not fit this definition because of its probabilistic nature. Hence Ackerman et al. proposed the notion of probabilistic k-richness claiming without proof that k-means has this property. It is proven in this paper, by example, that the version of k-means with random initialization does not have the property probabilistic k-richness, just rebuking Ackeman's claim.</p> Mieczysław Kłopotek Copyright (c) 2023 2023-01-11 2023-01-11 27 2 5 26 10.34739/si.2022.27.01 Artificial Neural Network based on mathematical models used in quantum computing <p>The article is a proposition of a new approach to building a neural model based on the system of Day-Ahead Market operating at TGE S.A. The reason for the proposed method is an attempt to find a better model for the DAM system. The proposed methodology is based on using mathematical models used in quantum computing. All calculations performed on learning the Artificial Neuron Network are based on operations described in Hilbert space. The main idea of calculations is to replace the data from the decimal system into the quantum state in Hilbert space and perform learning operations for a neural model of the DAM system in a special manner which relay on the teaching model for each position of the quantum register for all data. The obtained results were compared to the “classical” neural model with the use of a comparative model.</p> Dariusz Ruciński Copyright (c) 2023 2023-01-11 2023-01-11 27 2 27 48 10.34739/si.2022.27.02 Analysis of data quoted on the Day-Ahead Market of TGE S.A. using Statistics and Machine Learning Toolbox <p>The publication contains the results of research in the field of cluster analysis carried out using data quoted on the Day-Ahead Market of TGE S.A. Two methods were used in the analysis, one hierarchical known as the Ward’s method, and the other non-hierarchical - the k-means method. Many interesting research results have been obtained, which are illustrated, among others, in in the form of dendrograms, silhouette graphs and graphs in the form of clusters. Data on the volume and the volumeweighted average price of electricity were examined for various types of quotations: fixing 1, fixing 2 and continuous quotations. The research was carried out in the MATLAB and Simulink environments using a library called Machine and Statistics Learning Toolbox. Selected test results were interpreted.</p> Jerzy Tchórzewski Bartłomiej Longota Copyright (c) 2023 2023-01-11 2023-01-11 27 2 49 74 10.34739/si.2022.27.03 ICT security in revenue administration - incidents, security incidents - detection, response, resolve <p>The article shows the author's approach to the methods of acquiring and analyzing reports and security incidents, categorizing their sources in relation to the literature describing ICT security threats, taking into account the legal regulations in force in the Polish public administration. Methods of verification and analysis of detected threats, methods of threat resolution were presented. Tools and procedures used to evaluate reported incidents and assess the threat level of reported incidents were discussed. The incidents and events identified in the period April 2018 - February 2022 were analyzed. Due to the implementation of remote work, there were challenges related to the need to ensure secure remote access to ICT systems of the tax administration. This entailed the need to develop other methods of analysis, response and development of procedures for safe use of workstations by employees providing remote work. The article shows a wide variety of events that members of the security incident response team had to deal with. The obtained results will also be compared with the conducted scientific research on the perception of security threats in public administration and how changes in IT service in the studied organization influenced security management and affect the developed model of combating intentional security threats to information systems.</p> Tomasz Muliński Copyright (c) 2023 2023-01-11 2023-01-11 27 2 75 93 10.34739/si.2022.27.04 Optimizing the placement of BLE transmitters for Indoor Positioning Systems <p>The article presents the results of experimental research related to the optimization of the placement of BLE transmitters (beacons) inside rooms in order to locate the user. The experiments were carried out to check how far BLE transmitters can be moved away from each other so that the average localization error was at a level acceptable to the user. The value of the localization error was assumed based on the literature (less than 1 m). As a result of the conducted experiments, a mathematical formula was defined to calculate the required number of BLE transmitters for the exact location inside the rooms. The experiments used BLE transmitters, rooms inside the building of Siedlce University of Natural Sciences and Humanities and a mobile application with a database. In the study of the optimization of the placement of beacons, the fingerprint technique was used.</p> Marek Pilski Mateusz Aleksandrowicz Copyright (c) 2023 2023-01-11 2023-01-11 27 2 95 107 10.34739/si.2022.27.05 A methodology of identification and metaidentification research on the example of Day Ahead Market System <p>The paper contains selected research results in the field of identification and metaidentification of the Day Ahead Market system of TGE S.A. Due to the proposed new approach to identification, a methodology for conducting research has been developed, which requires eight stages. Then, both the tasks and research objectives as well as the form of research occurring at all stages of research in order to meet the distinguished specific objectives and the general purpose of the research were shown in detail. Then an example of both identification and metaidentification of Day Ahead Market systems was shown. The obtained models and metamodels confirm the need and possibility of conducting this type of research at TGE S.A.</p> Radosław Marlęga Copyright (c) 2023 2023-01-11 2023-01-11 27 2 109 137 10.34739/si.2022.27.06