JOURNAL OF ENGINEERING SCIENCE

STRUCTURAL ANALYSIS AND VIBRATION TESTING OF THE TUMnanoSAT MICROSATELLITE

2025-02-18T08:41:13+00:00

One of the important verification steps before the launch of the nanosatellite developed at Technical University of Moldova (TUMnanoSAT) was vibration testing of the real model. These tests were carried out according to the requirements submitted by the Japan Aerospace Exploration Agency (JAXA) in collaboration with which the launch of our nanosatellite was possible. Thus, in order to validate the structural integrity of CubeSat nanosatellites under launch loads, a 1U TestPod was designed and manufactured. This work presents hands-on experience of the vibration testing of the TUMnanoSAT microsatellite and simulation of static and dynamic loads. The dynamic behavior was analyzed by checking the harmonic oscillations (modal analysis and random vibrations) in order to avoid critical frequency (140 Hz). The testing facilities were provided by the Space Science Institute from Bucharest. The microsatellite was vibration tested in X, Y and Z axis directions according to special requirements. The numerical calculation model was developed in ANSYS Workbench. Comparison of the experimental results and numerical modal tests showed a good correlation within 10%.

ADVANCEMENTS IN SENSOR TECHNOLOGY FOR AUTONOMOUS WALKER

2025-02-18T08:36:52+00:00

This study presents a detailed analysis of gait trajectory and orientation using Time of Flight sensors and Inertial Measurement Units during controlled movement tests in a robotic walker. The tests were performed on three distinct path configurations: straight-line, rectangular, and lemniscate paths. The Time-of-Flight sensors measured changes in distance, while the Inertial Measurement Units captured yaw and orientation data. Notably, during sharp turns, the Time-of-Flight sensors detected significant distance fluctuations corresponding to the directional changes captured by the Inertial Measurement Units yaw data. The results highlight the effectiveness of combining Time of Flight and Inertial Measurement Units data to track stable movement, detect sudden turns, and monitor orientation adjustments in complex trajectories. This combined approach can offer critical insights for gait analysis, rehabilitation, and robotics navigation.

MEASURING PASSENGER SATISFACTION IN URBAN PUBLIC TRANSPORT IN CHISINAU

2025-02-18T08:44:40+00:00

The quality of services provided by the urban public transport system plays an essential role in determining the level of satisfaction of a city's inhabitants and in improving their quality of life. The analysis of the methods used to assess the quality of urban transport services reveals the need to adopt new concepts that more realistically reflect the various aspects of their quality. A critical aspect identified is the fact that traditional methods for assessing the quality of urban passenger transport fail to fully integrate the subjective perceptions of users. They usually focus on technical, operational or economic parameters, neglecting the importance of the personal experience and satisfaction felt by passengers. The integration of subjective perceptions and the use of advanced evaluation methods contribute to the development of a public transport system that better meets passengers' expectations, stimulating the use of public transport and reducing the negative impact on the urban environment.This article represents an application of the principal component analysis (PCA) method to assess the quality of services provided by the urban public transport system using the data collected during the study.This approach will allow for a more balanced assessment focused on the real needs of passengers, thus providing more solid support for decision-making and the implementation of measures to improve urban public transport.

IMPLEMENTATION OF INDUCTIVE PROCESSES IN GENERAL-PURPOSE EQUIPMENT TO ENHANCE HEAT TRANSFER PROCEDURES

2025-02-18T08:48:02+00:00

The paper explores the energy efficiency of general-purpose installations, particularly the equipment used in espresso coffee production, and the unique functions of hydraulic systems. By applying eco-design principles and innovative, efficient solutions, the negative impact on the environment can be significantly reduced, transforming citizens into eco-consumers. The study aimed to explore ways to decrease energy consumption in hydraulic systems of standard installations, particularly in heat transfer processes in solids and liquids, which account for up to 97% of energy consumption in such installations. An innovative solution is presented that converts electric energy into heat in liquids using inductive heat transfer. The instant heating inductive boiler, based on inductive heat transfer phenomena, eliminates the convective and conductive heat transfer losses associated with the operation of the boiler with the resistive heating element. The design methodology for dimensioning this type of equipment is provided, and the simulation model for necessary verifications in MatLab Simscape is created. With its practical benefits, the new inductive boiler reduces the preheating period to 7.5 s compared to the 90 s of systems with resistive heating elements, thereby eliminating the need to keep the coffee machine at operating temperatures during breaks and providing a reliable solution for energy efficiency.

ARCHITECTURE OF THE SPACE RADIATION SENSOR SATELLITE MODULE BASED ON ARTIFICIAL INTELLIGENCE

2025-02-18T08:55:11+00:00

This paper is dedicated to the study of the cosmic radiation and its effects on electronics, as well as methods to measure it in order to aid the elaboration of the architecture of the satellite module with space radiation sensors for classification and real-time analysis of cosmic radiation-induced fault patterns and state predictions the of electronic systems embedded in satellites. The architecture of the satellite module with an intelligent radiation sensor based on an FPGA device is proposed, which will include as radiation sensing elements arrays of various types of electronic memories (on semiconductors), both within the circuit and external nearby this circuit. A significant part of the FPGA circuit configuration consists in the development of acquisition, processing and communication procedures using structures with majoritz voting to exclude the influence of spatial radiation.

ANALYSIS AND EVALUATION OF ROMANIAN VOICE COMMANDS FOR THE CONTROL OF MECHATRONIC SYSTEMS

2025-02-18T08:57:51+00:00

This paper focuses on the analysis and evaluation of voice commands for controlling mechatronic systems in exceptional situations. It highlights the role and benefits of mechatronic devices in modern society, emphasizing their use across various fields, from industrial process automation and infrastructure to consumer electronics and energy. Significant benefits of these devices, such as comfort, efficiency, and technological innovation, are outlined, along with the risks associated with their use, including short circuits and electro-mechanical failures. The research is directed towards integrating voice emotion recognition technologies into the control systems of household appliances to handle exceptional situations. Emotion recognition from speech, based on artificial intelligence and voice signal processing, is described as an interdisciplinary approach that combines audio processing, voice feature extraction, and machine learning. The objectives include developing effective techniques and methods to classify emotions and ensure the safe operation of devices. Research results show the potential of these techniques and technologies to transform interactions with mechatronic systems, offering innovative solutions for enhancing performance and reducing the risks associated with complex activities. The study opens new directions for integrating artificial intelligence into production processes and creating safer, more intuitive working environments.

EXPLORING THE HUMAN CIRCULATORY SYSTEM THROUGH SYSTEM DYNAMICS: A MODEL-BASED APPROACH

2025-02-18T08:59:31+00:00

System dynamics is a robust methodology for understanding the behavior of complex systems over time. By employing feedback loops, stocks, flows, and time delays, this approach provides a comprehensive framework for simulating and analyzing dynamic systems. The application of system dynamics to the human circulatory system presents numerous possibilities, benefits, and practical applications that can significantly enhance our understanding and management of cardiovascular health. This article details experimental results from modeling myocardial infarction conditions using a six-compartment model developed in the NetLogo integrated development environment, incorporating BehaviorSpace for extensive simulations. For result analysis, specialized packages in R, Python, and Wolfram Mathematica were utilized to ensure rigorous data interpretation. The results demonstrate promising fidelity when compared to existing literature and real-time patient data, indicating the model's potential for clinical applications. By illustrating the interactions within the circulatory system, this research not only contributes to theoretical knowledge but also offers practical insights into disease management and intervention strategies, paving the way for improved cardiovascular health outcomes.

MEASURING THE IMPACT OF MOBILE APPLICATIONS

2025-02-18T09:04:31+00:00

Although mobile devices have widespread popularity, allowing, for example, companies to innovate, streamline operations, and maintain a competitive advantage in a rapidly evolving market, the economic impact of using mobile applications (apps) is less researched. In an attempt to improve the state of affairs in the field, this paper provides a classification (based on business domains) and defines models for calculating the costs of developing and using mobile apps in various situations. To evaluate the economic impact of mobile apps, the opportunity of use is argued and the mathematical expressions for calculating the quantitative indices, Net Present Value, Profitability and Internal Rate of Return, eventually in conjunction with the Equivalent Annual Value method, are determined for 12 specific cases of development and use of mobile apps. Also, multiple qualitative indices for measuring the impact of mobile apps are succinctly characterized and systematized. In confirmation of the significant economic and social impact of mobile apps, three implementations of them in various fields are described.

CASCADE CONTROL ALGORITHM OF THE ROBOTIC ARM'S SERVOMOTOR

2025-02-18T09:08:31+00:00

In this paper, there have been synthesized the control algorithms in cascade control systems. The control object is the robotic arm which is actuated by a servo motor presented as an automatic cascade control system which is consisting of two loops. The use of multiple loops is justified by the fact that with a single loop, only one parameter of the servo motor is controlled, which leads to a decrease in the reliability of the automatic system. A case study was carried out for a direct current electric motor, where proportional (P), proportional-integral (PI), and proportional-integral-derivative (PID) control algorithms were used, with P and PI applied to the inner loop, and P, PI, and PID to the outer loop. The system was simulated with the synthesized algorithms and the results were analyzed, it was established that the system has robustness and high performance for the case of using maximum stability degree method with iterations.

SELECTION OF DESIGN VALUES FOR PHYSICAL-MECHANICAL PROPERTIES IN THE CONSTRUCTIONS ON COLLAPSIBLE SOILS

2025-02-18T09:11:40+00:00

The article substantiated the necessity of detailed geological-engineering surveys during the design and construction on collapsible soils. A landslide incident on the Cahul-Giurgiulești railway line at 74th km was highlighted. Among the main causes there were the soaking of collapsible soils and the development of suffusion processes. A brief historical overview of the study of collapsible soils in Republic of Moldova was provided. The results of theoretical and laboratory studies aimed at further revealing the nature of collapsible soils were presented. The impact of additional soil moisture on the values of physical-mechanical property characteristics was studied. Based on the moisture-density theory, the dependencies of strength on consistency were constructed. It was established that the decrease in the strength of collapsible loams over time might have been caused by the disruption of rigid cementation bonds of structural cohesion (Cc) and the reduction of hydrocolloid cohesion (Σw) under conditions of changes in the existing natural moisture regime (consistency) due to additional moisture from engineering activities and the rise of the groundwater level. Recommended design values for physical-mechanical characteristic parameters for construction projects were provided.

ANALYSIS METHODOLOGY OF OPENSTREETMAP DATA COMPLETENESS (CASE STUDY: CHISINAU CITY)

2025-02-18T09:14:07+00:00

In recent years, special attention has been paid to free and open geospatial data sources accessible to the whole world, which have benefits for all sectors of the national economy. Taking into account the interest in this topic, the article proposes a data completeness analysis for OpenStreetMap, that is based on crowd sourcing, compared to data sources available at the national level, such as statistical information from Public Institution Real Estate Cadastre registers or the Spatial Data Infrastructure of the Republic of Moldova (NSDI), Agency Geodesy, Cartography and Cadastre. Thus, a general methodology for completeness analysis framework is designed based on the characteristics of OSM data, since is a well-known standard. Secondly, an attempt was made to apply a quality assessment model for OSM data through three different quality elements: completeness, thematic accuracy and positional accuracy based on the visual and quantitative analyses taking into account the spatial data that already exists on national platforms. The Chisinau city was selected as a case study/area of interest, and the results of the presented research can subsequently be applied to the entire Republic of Moldova. Based on the analysis performed, it can conclude that spatial data sources, whether from official sources or those based on crowd sourcing, still need to be supplemented with both spatio-temporal and qualitative information.

STATISTICAL EVALUATION OF DATA ON THE POLLUTION OF THE PRUT RIVER WITH AMMONIUM NITROGEN

2025-02-18T09:22:12+00:00

This paper analyzes the pollution of the Prut River with ammonium nitrogen (NH₄⁺) during the period 2019–2021, focusing on exceedances of the maximum allowable concentration (MAC) of 0.2 mg/L. The analyzed data comes from measurements taken in various localities along the river. The results indicate constant pollution with significant exceedances of the MAC, the highest measured concentration being 3.85 mg/L. Descriptive analysis reveals an asymmetric distribution, with extreme values raising the average to 0.8456 mg/L. The 2019–2021 period was chosen because this interval recorded significant MAC exceedances. Urban localities, such as Leova and Lipcani, show the highest concentrations, and are correlated with intense human activities. The conclusions emphasize the need for urgent action to reduce pollution and protect aquatic ecosystems and public health.

THE ROLE OF PROCYANIDINS IN GRAPES AND WINES: EFFECTS ON QUALITY AND COMPOSITION

2025-02-18T09:24:39+00:00

Proanthocyanidins in grapes and wine are oligomers and polymers of flavan-3-ols, predominantly connected through C4–C8 and/or C4–C6 bonds (B-type). These compounds significantly influence red wine’s sensory profile, particularly its color and mouthfeel. In addition, proanthocyanidins are recognized for their antioxidant and radical-scavenging properties, capable of neutralizing reactive oxygen species and preventing cellular damage caused by oxidative stress. These properties give them an important role in protecting health, with beneficial effects on the body by reducing the risk of cardiovascular diseases and cancer. The aim of the article is to explore the role of proanthocyanidins in grapes and wine, focusing on their contributions to wine’s sensory characteristics such as color, astringency, and mouthfeel. It aims to examine the factors influencing their composition, the transformations they undergo during winemaking and aging, and their broader implications for wine quality, stability, and health benefits. The objectives of the study are to investigate the physical, chemical, and biochemical properties of procyanidins, as well as the influence of factors such as grape variety, ripeness, health status, climatic conditions, viticultural techniques, grape processing methods, wine stabilization, and aging techniques on their content.