1. Experimental and numerical investigation of Rayleigh-Benard convection in rectangular cavity with motor oilPredrag Živković, Mladen A. Tomić, Sadoon Ayed, Cristian Barz, Drago Sever, 2023, izvirni znanstveni članek 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: 0
 Celotno besedilo (3,41 MB)
Gradivo ima več datotek! Več... |
2. Study on the compression effect of clothing on the physiological response of the athleteMarianna Halász, Jelka Geršak, Péter Bakonyi, Gabriella Oroszlány, András Koleszár, Orsolya Nagyné Szabó, 2022, izvirni znanstveni članek Opis: The study aimed to analyze whether the high compression of unique, tight-fitting sportswear
influences the clothing physiology comfort of the athlete. Three specific sportswear with different
compression were tested on four subjects while they were running on a treadmill with increasing
intensity. The compression effect of the sportswear on the body of the test persons, the temperature
distribution of the subjects, and the intensity of their perspiration during running were determined.
The results indicate that the compression effect exerted by the garments significantly influences the
clothing physiology comfort of the athlete; a higher compression load leads to more intense sweating
and higher skin temperature.
Ključne besede: clothing physiology, tight-fitting sportswear, running test on a treadmill, thermal comfort, skin temperature, perspiration
Objavljeno v DKUM: 21.03.2025; Ogledov: 0; Prenosov: 0
Celotno besedilo (3,48 MB)
Gradivo ima več datotek! Več... |
3. High resolution short response time fiber-optic temperature sensorNermin Sinanović, Simon Pevec, Matej Njegovec, Vedran Budinski, Denis Đonlagić, 2025, izvirni znanstveni članek Opis: This article presents an all-silica microwire optical sensor designed for both fast response time and high-resolution temperature detection. The sensor consists of a thin optical microwire created at the tip of an optical fiber, configured as a temperature sensitive Fabry–Perot interferometer (FPI). For the purposes of achieving rapid response times, the sensing section of the sensor has a diameter of 11 µm. Experimental bench tests were set up to evaluate the sensor’s static and dynamic performance. The results indicate a sensor system resolution of about 5 mK and demonstrate a bandwidth of 38 Hz that corresponds to a response time of 4 ms in still air. The sensor’s functionality is shown through a basic periodic gas compression method detecting small temperature fluctuations. In addition, the sensor was demonstrated for operation up to 600 ◦C.
Ključne besede: Fabry-Perot, high-resolution temperature sensor, micromachining, microwire optic sensor, optical fibers, short response time
Objavljeno v DKUM: 12.02.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (8,03 MB) |
4. A short-range quasi-distributed strain and temperature sensing system utilizing a standard telecom laser diodeJure Javornik, Denis Đonlagić, 2025, izvirni znanstveni članek Opis: This article presents a short-range fiber-optic quasi-distributed sensing device suitable for strain and temperature measurement. The sensing assembly consists of an fs laser inscribed reference mirror and a sensing array of equidistantly positioned mirrors. Utilization of the reference mirror and proper sensor geometry selection provides the possibility for a high-resolution spectral interrogation of the sensing array while relying on an ordinary, cost-effective distributed feedback (DFB) telecom laser diode. Beside the telecom DFB diode, the entire interrogation system includes only an additional detector, optical coupler, analog interface and a microcontroller. Measurement resolution better than 1 µε was demonstrated experimentally at a sampling rate exceeding 65 samples per second, while utilizing a sensing device with a typical length of 50 mm and spatial resolution of approximately 2 mm. To demonstrate the application potential of the proposed measuring device, a few different packages and sensor configurations were demonstrated and tested, including a system for tactile sensing applications and a short-range quasi-distributed temperature measurement probe.
Ključne besede: optical fiber sensors, short-range quasi-distributed fiber-optic sensor, strain/temperature sensing device, cost-effective interrogation system, tactile sensing, phase subtraction
Objavljeno v DKUM: 03.02.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (6,44 MB) |
5. Long-term temperature prediction with hybrid autoencoder algorithmsJorge Pérez-Aracil, Dušan Fister, C. M. Marina, César Peláez-Rodriguez, L. Cornejo-Bueno, P. A. Gutiérrez, Matteo Giuliani, A. Castelleti, Sancho Salcedo-Sanz, 2024, izvirni znanstveni članek Opis: This paper proposes two hybrid approaches based on Autoencoders (AEs) for long-term temperature prediction. The first algorithm comprises an AE trained to learn temperature patterns, which is then linked to a second AE, used to detect possible anomalies and provide a final temperature prediction. The second proposed approach involves training an AE and then using the resulting latent space as input of a neural network, which will provide the final prediction output. Both approaches are tested in long-term air temperature prediction in European cities: seven European locations where major heat waves occurred have been considered. The longterm temperature prediction for the entire year of the heatwave events has been analysed. Results show that the proposed approaches can obtain accurate long-term (up to 4 weeks) temperature prediction, improving Persistence and Climatology in the benchmark models compared. In heatwave periods, where the persistence of the temperature is extremely high, our approach beat the persistence operator in three locations and works similarly in the rest of the cases, showing the potential of this AE-based method for long-term temperature prediction.
Ključne besede: autoencoder, temperature prediction, hybrid models, heatwave
Objavljeno v DKUM: 29.01.2025; Ogledov: 0; Prenosov: 2
Celotno besedilo (1,82 MB) |
6. Regulator temperature s krmilnikom pid : diplomsko deloMiha Jerebic, 2024, diplomsko delo Opis: Učinkovito vzdrževanje želene temperature je bistveno za zagotavljanje udobja, varnosti in optimalnega delovanja različnih sistemov. V ta namen se uporabljajo regulatorji temperature, ki omogočajo natančen nadzor nad temperaturo in zagotavljajo stabilno delovanje. V nalogi opišemo različne vrste regulatorjev temperature, njihove uporabe ter s tem povezano elektroniko na splošno. Posebno pozornost v nalogi namenjamo regulatorjem s proporcionalno-integracijsko-diferencialnimi krmilniki in kot praktični primer opišemo postopek načrtovanja v programu Altium Designer in izdelavo končnega izdelka v fizični obliki. Delovanje izdelka preverimo tudi z meritvami s pomočjo oscilatorja, ki nam ponudijo vpogled v pomanjkljivosti izdelanega regulatorja in njegove potencialne izboljšave.
Ključne besede: regulator temperature, temperatura, tiskanina, PID
Objavljeno v DKUM: 14.10.2024; Ogledov: 0; Prenosov: 13
Celotno besedilo (3,52 MB) |
7. The importance of thermally abnormal waters for bioinvasions - a case study of Pistia stratiotesNina Šajna, Tina Urek, Primož Kušar, Mirjana Šipek, 2023, izvirni znanstveni članek Opis: Thermally abnormal waters represent safe sites for alien invasive plants requiring warmer conditions than provided by the ambient temperatures in the temperate zone. Therefore, such safe sites are frequently inhabited by tropical and sub-tropical plants. By performing a literature review we assessed that at least 55 alien aquatic plant taxa from 21 families were found in thermally abnormal waters in Europe. The majority of these taxa are submerged or rooted macrophytes. Six taxa are listed as quarantine pests according to EPPO. Among these, Pistia stratiotes is present in seven European countries, most of the records of this presence being recent. We studied P. stratiotes in a thermally abnormal stream where a persistent population was able to survive harsh winters. Models showed that the optimum temperature for P. stratiotes biomass was 28.8 ± 3.5 ◦C. Here, we show that air temperatures had a higher influence on the photosynthetic efficiency of P. stratiotes, estimated by chlorophyll fluorescence measurements, than did water temperatures. Generally, growth, and consequently surface cover for free-floating plants, cannot be explained solely by thermally abnormal water temperatures. We conclude that even though the majority of thermophile alien plant occurrences resulted from deliberate introductions, thermally abnormal waters pose an invasion risk for further deliberate, accidental, or spontaneous spread, which might be more likely for free-floating macrophytes.
Ključne besede: macrophytes, alien invasive plants, chlorophyll fluorescence, plant mass, temperature gradient
Objavljeno v DKUM: 05.06.2024; Ogledov: 158; Prenosov: 30
Celotno besedilo (3,03 MB)
Gradivo ima več datotek! Več... |
8. Slow growth storage of Berula erecta in vitro - effect of sucrose, sorbitol and temperatureJana Ambrožič-Dolinšek, Sanja Oblonšek, Terezija Ciringer, 2022, izvirni znanstveni članek Opis: It has been established that in vitro storage of Berula erecta (Huds.) Coville by slow growth would rationalize the culture maintenance by reducing the number of transfers to fresh medium. Attempts of slow growth were made while maintaining viability by adding sugars and sugar alcohols to the MS medium and lowering the culture temperature in the growth chambers. The effect of low temperatures (13°C and 4°C), different combinations and concentrations of sorbitol (20, 40 g L-1) and sucrose (30, 40 g L-1), and light was tested to determine the viability and ability of B. erecta to recover growth. Increasing sucrose concentration did not inhibit or slow growth. At 23 ± 2°C, the addition of 20 g L-1 sorbitol successfully inhibited growth, while the addition of 40 g L-1 sorbitol resulted in plant senescence after two months of culturing. Storage of B. erecta at 13°C did not effectively inhibit growth and recovery ability in any treatment. The most effective way to maintain B. erecta for long-term slow growth storage in tissue culture while retaining a high level of viability with minimal growth was to culture the plants at 4°C in the dark. This kept the plants viable and capable of regeneration for several months.
Ključne besede: slow growth storage, viability, sucrose, sorbitol, temperature, Berula erecta
Objavljeno v DKUM: 23.05.2024; Ogledov: 204; Prenosov: 7
Celotno besedilo (878,32 KB)
Gradivo ima več datotek! Več... |
9. Solidification Behavior of Fe-6.5Si Alloy Powder for AM-SLM Processing, as Assessed by Differential Scanning CalorimetryDarja Steiner Petrovič, Črtomir Donik, Irena Paulin, Matjaž Godec, Maja Vončina, Martin Petrun, 2023, izvirni znanstveni članek Ključne besede: kalorimetrija, kisik, visoke temperature, mikrostrukture, soft magnetic alloy, differential scanning calorimetry, oxygen, high-temperature phase, microstructure, eutectics
Objavljeno v DKUM: 22.05.2024; Ogledov: 128; Prenosov: 13
Celotno besedilo (9,05 MB)
Gradivo ima več datotek! Več... |
10. Carbon-free heat production for high-temperature heating systemsSven Gruber, Klemen Rola, Danijela Urbancl, Darko Goričanec, 2023, izvirni znanstveni članek Opis: The article presents a new carbon-free heat production technology for district heating, which consists of a combined heat and power generation fuel cell (FC CHP) with CO2 capture and a two-stage cascade high-temperature heat pump (TCHHP). The FC generates heat and electricity, the latter being used to drive the compressors of the TCHHP. During the winter period, the water temperature achieved can occasionally be too low, so it would be heated up with hydrogen gas boilers. The hydrogen would be produced by reforming natural gas, synthetic methane, or biogas. The results are presented with natural gas utilization—the ratio between the obtained heat flow transferred directly to the water for district heating and the input heat flow of natural gas. In the case of a return water temperature of 60 °C and district heating temperature of 85 °C, the TCHHP, whose heat source is groundwater, achieves plant efficiency of 270.04% in relation to the higher heating value (HHV) and 241.74% in relation to the lower heating value (LHV) of natural gas. A case with a TCHHP whose heat source is low-temperature geothermal water achieves a plant efficiency of 361.36% in relation to the HHV and 323.49% in relation to the LHV.
Ključne besede: carbon-free, decarbonization of district heating systems, fuell cell, high-temperature district heating, high-temperature heat pump
Objavljeno v DKUM: 10.05.2024; Ogledov: 233; Prenosov: 17
Celotno besedilo (3,32 MB)
Gradivo ima več datotek! Več... |
