Iskanje po katalogu digitalne knjižnice

Opis: This paper shows the possibility of applying artificial intelligence methods in milling, as one of the most common machining operations. The main goal of the research is to obtain reliable intelligent models for selected output characteristics of the milling process, depending on the input parameters of the process: depth of cut, cutting speed and feed to the tooth. One of the problems is certainly determining the value of input parameters of the processing process depending on the objective function, i.e. the output characteristics of the milling process. The selected objective functions in this paper are the temperature in the cutting zone and arithmetic mean roughness of the machined surface. The paper examines the accuracy of three models based on artificial intelligence, obtained through artificial neural networks, fuzzy logic, and genetic algorithms. Based on the mean percentage error of deviation, conclusions were drawn as to which of the three models is most adequately applied and implemented in appropriate process systems, which are based on artificial intelligence.
Ključne besede: artificial intelligence, artificial neural networks (ANN), fuzzy logic, genetic algorithms (GA), face milling, modelling, surface roughness, cutting temperature
Objavljeno v DKUM: 15.01.2026; Ogledov: 0; Prenosov: 0
Celotno besedilo (2,12 MB)
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Opis: The aim of this paper is to present a novel and comprehensive methodology for the dynamic modeling and experimental validation of a photovoltaic/thermal system. The dynamic model is divided into thermal and electrical subsystems, encompassing the photovoltaic/ thermal module and the thermal energy storage. The thermal subsystem of both the photovoltaic/thermal module and the thermal energy storage is described by a one-dimensional dynamic model of heat transfer mechanisms and optical losses, while the electrical subsystem is presented as an electrical equivalent circuit of double diode solar cell. Model validation was conducted on a modern experimental photovoltaic/thermal system over an extended operational period at a five-minute resolution, with validation days classified as sunny, cloudy, or overcast based on weather conditions, thereby demonstrating an applied approach. The results demonstrate the lowest deviation values reported to date, confirmed using six quantitative indicators. The added value of the proposed methodology, not previously addressed in the literature, lies in the following contributions: (i) comprehensive modeling of the entire photovoltaic/thermal system, (ii) accurate consideration of optical losses in the photovoltaic/thermal module, and (iii) long-term experimental validation. Overall, the proposed methodology provides a reliable and efficient framework for PV/T system design, optimization, and long-term performance assessment.
Ključne besede: photovoltaic/thermal system, thermal energy storage, dynamic modeling, experimental validation, heat transfer mechanism, temperature, electrical power
Objavljeno v DKUM: 10.11.2025; Ogledov: 0; Prenosov: 10
Celotno besedilo (7,15 MB)
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Opis: In this article, a study was conducted on the design of smart trousers to improve the thermal comfort of the legs of paraplegics. It was based on the survey of paraplegics about the thermoregulation of their legs in cold environments, the warming of the legs during and after outdoor activities, the type of clothing for outdoor activities and the need for smart heating clothing for the lower extremities. The skin surface temperatures on the legs of fully mobile people and paraplegics were measured in a neutral state to find out to which temperature the microclimate inside the trousers can be warmed and the smart trousers can be used safely. The survey of paraplegics was conducted nationwide and included sixty-one adult male and female subjects. Skin surface temperatures were measured at eight measurement points on the right and left leg and performed on eighteen participants. After evaluating all the results of this study, recommendations for the design of smart heating trousers were proposed. The results of this part of the research can provide designers with important information about the specific requirements for smart heating trousers and enable them to design and develop products that meet real needs and are safe for paraplegic wheelchair users. Furthermore, this work aims to raise awareness of the needs of wheelchair users that enable them to integrate into the social environment on an equal footing.
Ključne besede: paraplegics, cold protection, thermal comfort, legs skin surface temperature, smart heating trousers design
Objavljeno v DKUM: 22.07.2025; Ogledov: 0; Prenosov: 0

Opis: This study sets out to examine the effects of hedgerow shading on soil physical properties, specifically soil gravimetric water content and soil temperature. Analyses of both soil parameters were conducted at two locations with different shade proportion. The aim of the study was to address the links between hedgerow shading and basic physical soil properties which could be significant both for agricultural production and for ecological processes in agroecosystems. At both locations, soil samples and measurements were taken at different distances from hedgerow and in different time intervals. Diurnal shading variation at certain distances from the hedgerow on Location 1 and 2 was calculated with the software toll for Arboriculturists. At Location 1 shading is consistently high throughout the year, ranging from 76 to 100%. In contrast, shading at Location 2 varies from 1 to 25%. The results reveal that hedgerows at Location 1, do not have a statistically significant impact on gravimetric soil water content and soil temperature across the entire plot surface. Additionally, the percentage of shading is only marginally decreases with distance. Conversely, Location 2 exhibits an increase in soil temperature and a slight but (non-significant) decrease in soil gravimetric water content as the distance from the hedgerow increases., The total mean shading at Location 2 is considerably lower compared to Location 1, and the shading percentage declines more at the distance from the hedgerow increases. Overall, lower soil temperatures and higher gravimetric soil water content where observed at the more shaded Location 1. The research outcomes are helpful in agricultural production planning as well as in the evaluation of hedgerows for the needs of agricultural policy.
Ključne besede: soil water content, soil temperature, hedgerow, sunlight
Objavljeno v DKUM: 11.04.2025; Ogledov: 0; Prenosov: 6
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Opis: Naturally flows have been the scope of the scientific research for centuries, Rayleigh-Benard convection being one of the leading. Many researchers have considered the flow patterns, boundary conditions, various cavities, nanofluids, theoretically, numerically, and experimentally. The flow was investigated in atmosphere and in nanofluids, in air, water, molten metals, non-Newtonian fluids. Almost all research focuses on 2-D or 3-D analysis of flow in laterally unlimited enclosures, as parallel plates or coaxial cylinders. In technical practice, only limited enclosures exist. This paper presents numerical and real experimental results for the test chamber with ratio 4×2×1 in x-, y-, and z direction, respectfully. The measurements were taken at fifteen different positions on the faces of the tank. Probes used are PT100 elements. As the chamber is limited in all directions, the results have shown strong influence of the lateral walls. The results are compared with the those obtained by IR camera. Various fluids were tested, and results for motor oil will be presented.
Ključne besede: Rayleigh-Bénard convection, temperature profile, PT100 probe, motor oil, numerical simulation
Objavljeno v DKUM: 27.03.2025; Ogledov: 0; Prenosov: 1
Celotno besedilo (3,41 MB)
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