1. 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: 2
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2. 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: 1
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3. 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: 9
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4. 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
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5. 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: 6
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6. 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
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7. 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
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8. Measurements of Small Frequency Differences by Dual Mode 4 MHz Quartz SensorsVojko Matko, 2023, izvirni znanstveni članek Opis: We proposed a method for measuring frequency differences of the order of a few Hz with an experimental error lower than 0.0001% by using two 4 MHz quartz oscillators, the frequencies of which are very close (a few 10 Hz difference) due to the dual mode operation (differential mode with two temperature-compensated signal frequencies or a mode with one signal and one reference frequency). We compared the existing methods for measuring frequency differences with the new method which is based on counting the number of transitions through zero within one beat period of the signal. The measuring procedure requires equal experimental conditions (temperature, pressure, humidity, parasitic impedances etc.) for both quartz oscillators. To ensure equal resonant conditions for oscillation two quartz crystals are needed, which form a temperature pair. The frequencies and resonant conditions of both oscillators must be almost equal, which is achieved by an external inductance or capacitance. In such a way, we minimized all the external effects and ensured highly stable oscillations and high sensitivity of the differential sensors. The counter detects one beat period by an external gate signal former. By using the method of counting transitions through zero within one beat period, we reduced the measuring error by three orders of magnitude, compared to the existing methods. Ključne besede: small frequency difference measurement, temperature-compensated quartz sensors, differential sensors, quartz oscillators, transitions-through-zero method Objavljeno v DKUM: 26.03.2024; Ogledov: 357; Prenosov: 246
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9. Loss of oxygen atoms on well-oxidized cobalt by heterogeneous surface recombinationDomen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, izvirni znanstveni članek Opis: Calorimetry is a commonly used method in plasma characterization, but the accuracy of the method is tied to the accuracy of the recombination coefficient, which in turn depends on a number of surface effects. Surface effects also govern the kinetics in advanced methods such as atomic layer oxidation of inorganic materials and functionalization of organic materials. The flux of the reactive oxygen atoms for the controlled oxidation of such materials depends on the recombination coefficient of materials placed into the reaction chamber, which in turn depends on the surface morphology, temperature, and pressure in the processing chamber. The recombination coefficient of a well-oxidized cobalt surface was studied systematically in a range of temperatures from 300 to 800 K and pressures from 40 to 200 Pa. The coefficient increased monotonously with decreasing pressure and increasing temperature. The lowest value was about 0.05, and the highest was about 0.30. These values were measured for cobalt foils previously oxidized with oxygen plasma at the temperature of 1300 K. The oxidation caused a rich morphology with an average roughness as deduced from atomic force images of 0.9 µm. The results were compared with literature data, and the discrepancy between results reported by different authors was explained by taking into account the peculiarities of their experimental conditions. Ključne besede: heterogeneous surface recombination, recombination coefficient, cobalt, cobalt oxide, temperature dependence, pressure dependence, plasma, oxygen Objavljeno v DKUM: 26.03.2024; Ogledov: 228; Prenosov: 18
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10. Development of the smart T-shirt for monitoring thermal status of athletesSandra Stojanović, Jelka Geršak, Suzana Uran, 2022, izvirni znanstveni članek Opis: Athletes are often subjected to a great physical strain during training and competition. Sport activities performed in hot and humid conditions may result in different heat illnesses with mild or fatal consequences. Against this background it is important to know the thermal state of athletes during physical activity.
This article presents the development of a smart T-shirt for monitoring the thermal status of an athlete. The smart T-shirt was created by embedding an electronic system with temperature and humidity sensors that allows the measurement of temperature and the relative humidity of the microclimate. A smart T-shirt is comfortable, and integrated sensors and electronics do not affect wearing comfort. A good concurrence between the temperature and humidity results from using the smart T-shirt, and thus the medical device was achieved. Data obtained can be of great importance to the sports staff who will be able to monitor the athletes' thermal state during matches and competitions. Ključne besede: smart T-shirt, microclimate temperature, relative humidity of the microclimate Objavljeno v DKUM: 26.03.2024; Ogledov: 190; Prenosov: 19
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