The article discusses the issues associated with the preparation of hot water in individual apartment heating systems that use a secondary plate heat exchanger of the boiler. The drawbacks of this approach are highlighted, including delays in hot water supply, the need to drain water from the pipeline, the inability to regulate temperature and flow rate, as well as the lack of recirculation capabilities. As an alternative, a system with a storage tank and a plate heat exchanger is proposed, which ensures stable water temperature, adjustable flow rate, resource savings, and the possibility of recirculation. Based on experimental studies, the heat transfer coefficient for heat exchangers with profiled and flat plates has been determined. Calculations of the required heat exchanger area are provided, depending on the type of plates, the volume of the storage tank, and its charging time, which allows for the optimization of hot water supply system design.

Keywords: plate heat exchanger, storage tank, heat transfer coefficient

This study examines the control of the cooling fan speed as an effective means of reducing emissions of volatile organic compounds during three-dimensional layer-by-layer printing. The high extrusion temperatures used in modern high-speed printers lead to emissions of harmful volatile organic compounds, which poses health risks in poorly ventilated rooms. A mathematical model has been developed to establish a quadratic relationship between the fan speed and the volumetric air flow, which directly affects the deposition of volatile organic compounds on the melt surface. The experimental setup uses relay control of the motor current and proportional-integral-differentiating speed control, ensuring rapid stabilization of the air flow with minimal overshoot. From the analysis of transient characteristics, including motor current, fan speed, airflow velocity, and power consumption, it is shown that precise control of fan speed creates stable and predictable airflow movement, significantly reducing emissions of volatile organic compounds. In addition, the results show that integrating the feedback of the volatile organic compounds sensor in real time with the control of the extrusion rate can offer an even more adaptive and effective strategy for reducing emissions. This research lays the foundation for safer and more efficient 3D printing processes with layer-by-layer deposition modeling through improved temperature and emission management.

Keywords: volatile organic compounds, three-dimensional printing, adaptive control, layer-by-layer deposition, regulation

The article deals with the principles of creating software used as part of sensing systems for restoring the visibility of the gas smoke protection service link in a smoke-filled environment during rescue operations. The architectural part of the device and the description of algorithms of the device operation are described. Attention is paid to the methods of forming a digital model of obstacle heights and visualization of the spatial situation. Approaches to filtering of erroneous sensor values and selection of significant contours of objects, processing of data from ultrasonic grating, infrared sensors, as well as temperature and humidity sensors are given. The role of the device in providing accurate navigation, reducing the time to search for the fire center and improving the overall safety of the gas smoke protection service unit when working in a smoky environment is emphasized.

Keywords: smoke protection service, smoke-filled environment, sensing device, algorithms, software, firefighting, reconnaissance, modeling, navigation, sensor data

The article develops calibration methods to improve accuracy and reduce operating costs of robotic systems in warehouse logistics. Special attention is given to the use of laser sensors and offset parameters, enabling the robot's position to adapt to changing conditions. The methodology includes the stages of initialization, orientation, and final verification, which help minimize deviations and reduce the need for manual adjustments. This approach ensures consistent operational accuracy and lowers operating costs through automated and adaptive robot calibration settings.

Keywords: robot calibration, warehouse automation, laser sensor, offset, positioning accuracy, robotic system, adaptive calibration, automatic calibration, collaborative robot, cobot

When designing engineering protection, it is necessary to use modern and progressive technologies. The technical decisions made must comply with the fundamentals of design - economic and operational efficiency. This article discusses the methods and principles of operation necessary for hazard assessment and the development of effective measures to prevent and reduce risks in the design, selection of optimal solutions and recommendations for the development of engineering protection projects. A section of a public highway of local significance in the Krasnodar Territory was selected during the survey. The materials of engineering and geological studies of the slope were used as initial data, which included reconnaissance route observations, engineering and geological workings with soil sampling, and determination of the physico-mechanical characteristics of the soils.

Keywords: engineering protection, surveys, design, stability, reconstruction, soil, landslide slope

Currently, key aspects of software development include the security and efficiency of the applications being created. Special attention is given to data security and operations involving databases. This article discusses methods and techniques for developing secure applications through the integration of the Rust programming language and the PostgreSQL database management system (DBMS). Rust is a general-purpose programming language that prioritizes safety as its primary objective. The article examines key concepts of Rust, such as strict typing, the RAII (Resource Acquisition Is Initialization) programming idiom, macro definitions, and immutability, and how these features contribute to the development of reliable and high-performance applications when interfacing with databases. The integration with PostgreSQL, which has been demonstrated to be both straightforward and robust, is analyzed, highlighting its capacity for efficient data management while maintaining a high level of security, thereby mitigating common errors and vulnerabilities. Rust is currently used less than popular languages like JavaScript, Python, and Java, despite its steep learning curve. However, major companies see its potential. Rust modules are being integrated into operating system kernels (Linux, Windows, Android), Mozilla is developing features for Firefox's Gecko engine and StackOverflow surveys show a rising usage of Rust. A practical example involving the dispatch of information related to class schedules and video content illustrates the advantages of utilizing Rust in conjunction with PostgreSQL to create a scheduling management system, ensuring data integrity and security.

Keywords: Rust programming language, memory safety, RAII, metaprogramming, DBMS, PostgreSQL

This work is devoted to describing the development and integration of two key subsystems of an insect-like six-legged robot: a gait control module and a computer vision system for autonomous navigation. It examines architectural solutions, algorithmic foundations, and the practical implementation of components that ensure stable movement and intelligent interaction of the robot with its surroundings.

Keywords: insect-like robot, gait control module, computer vision, autonomous navigation, ROS2, SLAM, RTABMap, NAV2, OctoMap, tripod gait, Raspberry Pi, LiDAR

This paper presents a highly technical implementation of an ECG-based biometric identification system utilizing deep learning models for both verification and closed-set identification. We propose a dual-model architecture comprising a Siamese neural network for one-to-one verification and a deep convolutional neural network (CNN) for one-to-many classification. The methodology includes comprehensive signal preprocessing, data augmentation to simulate physiological variability, and feature extraction tailored to ECG characteristics. Experimental evaluation on benchmark ECG datasets demonstrates the effectiveness of the proposed system. The Siamese network achieves high verification accuracy with low equal error rates, while the CNN classifier attains state-of-the-art identification accuracy (exceeding 98% on average) across enrolled subjects. Key performance metrics—accuracy, precision, recall, and F1-score—indicate robust performance, outperforming several existing biometric methods. The results highlight the viability of ECG-based authentication in real-world applications.

Keywords: biometric authentication, electrocardiogram (ECG), siamese neural network, convolutional neural network, qrs complex, signal processing

In this paper, a star sensor tracking method without a star library based on the angular distance chain algorithm is proposed to solve the problem that traditional star sensors rely on a fixed star library and need to be configured to work with multiple units in the tracking mode. This method achieves star map matching by dynamically generating angular distance chains, avoiding the dependence on the global star library. Experiments show that the recognition time of the algorithm in the tracking mode is reduced to milliseconds, and the maximum pose determination error is no more than 0.035°, which proves its effectiveness and reliability. The study provides key technical support for the development of low-cost and lightweight star sensors that are suitable for scenarios such as deep space exploration and near-Earth satellite clusters.

Keywords: angular distance chain algorithm, star sensor without star library, star map recognition, tracking mode, orientation, dynamic matching, deep space exploration

The article proposes to strengthen the upper chord of the triangular spacer system with fiberglass. The material used for strengthening shows high efficiency in increasing the strength of the wooden element for the 1st group of limit states. The material proposed for strengthening does not lead to a change in the original decorative expressiveness of wooden structures, and maintains the service life.

Keywords: spacer structure, upper chord, glued laminated board element, modulus of elasticity, volumetric weight, geometric characteristics, bending moment, longitudinal compressive force, structural reinforcement, composite material

The article presents the method of multiple initial connections aimed at enhancing the information security of peer-to-peer virtual private networks. This method ensures the simultaneous establishment of several initial connections through intermediate nodes, which complicates data interception and minimizes the risks of connection compromise. The paper describes the algorithmic foundation of the method and demonstrates its application using a network of four nodes. An analysis of packet routing is conducted, including the stages of packet formation, modification, and transmission. To calculate the number of unique routes and assess data interception risks, a software package registered with the Federal Service for Intellectual Property was developed. The software utilizes matrix and combinatorial methods, providing high calculation accuracy and analysis efficiency. The proposed method has broad application prospects in peer-to-peer networks, Internet of Things systems, and distributed control systems.

Keywords: multiple initial connections, peer-to-peer network, virtual private network, information security, data transmission routes, intermediate nodes, unique routes

The article discusses the main methods of carbon black granulation, and compares the results with an existing industrial installation. The granulation process is necessary to convert powdered carbon black into homogeneous granules in order to simplify its further transportation and use. Despite the wide variety of granulation methods, there are problems with the uniformity of granules, equipment wear, and the formation of stagnant zones. As a result of the experiments conducted on the laboratory granulator described in the article, photos of the results are provided. Each of the methods used has a description of stagnation zones, which allows us to conclude that the most efficient method is to convert powdered carbon black into granules.

Keywords: pelletizing, wear, granulator, rotor fingers, experiment, technique, carbon black

Explicit formulas for the spectral characteristic and optimal linear filtration operator with a forecast for stochastic L–Markov processes are obtained using methods of spectral analysis of random processes, the theory of functions of a complex variable, and using stochastic differential-difference equations. An interesting example of an optimal filtration operator with a forecast for an L-Markov process with a quasi-rational spectral density generalizing the rational one is constructed for technical applications. It is shown that the forecast filtering operator is the sum of a linear combination of the values of the received signal at some time points and the integral of an exponentially decaying weight function.

Keywords: random process, L-Markov process, prediction filtering, spectral characteristic, filtration operator

The article presents an algorithm for establishing a secure connection for peer-to-peer virtual private networks aimed at enhancing information security. The algorithm employs modern cryptographic protocols such as IKEv2, RSA, and DH, providing multi-level data protection. The developed algorithm structure includes dynamic generation and destruction of temporary keys, reducing the risk of compromise. The proposed solution is designed for use in corporate network security systems, Internet of Things system, and distributed systems.

Keywords: virtual Private Network, peer-to-peer network, cryptographic protocols, RSA, Diffie-Hellman, IKEv2, secure connection, multi-layer protection, information security, distributed systems

This article examines the vulnerability associated with storing image files in the cache on the device's hard disk in unencrypted form. The nature of this problem and the possible consequences of its exploitation, including leakage of confidential data, abuse of information received and risks to corporate information systems, are being investigated. The main attention is paid to the method of protection against this vulnerability, which is based on the use of masking techniques using orthogonal matrices.. The developed prototype of the messenger is presented, in which this method is implemented: images are transmitted and stored in the file system in masked form, the unmasking process is carried out directly in the messenger application itself.

Keywords: information security, messenger, messaging, communications, instant messaging systems, encryption, orthogonal matrices