1. Mathematical modeling of the floating sleeper phenomenon supported by field measurements : Mojmir Uranjek, Denis Imamović and Iztok PerušMojmir Uranjek, Denis Imamović, Iztok Peruš, 2024, izvirni znanstveni članek Opis: This article aims to provide an accurate mathematical model with the minimum number of degrees of freedom for describing the floating sleeper phenomenon. This was accomplished using mathematical modeling supported by extensive field measurements of the railway track. Although the observed phenomenon is very complex, the simplified single degree of freedom (SDOF) mathematical model proved accurate enough for its characterization. The progression of the deterioration of the railway track was successfully correlated to changes in the maximal dynamic factor for different types of pulse loading. The results of the presented study might enable the enhanced construction and maintenance of railroads, particularly in karst areas.
Ključne besede: floating sleepers, dynamic factor, pulse loading, field measurements, SDOF mathematical model
Objavljeno v DKUM: 28.11.2024; Ogledov: 0; Prenosov: 2
 Celotno besedilo (6,27 MB)
Gradivo ima več datotek! Več... |
2. Precision magnetometry exploiting excited state quantum phase transitionsQian Wang, Ugo Marzolino, 2024, izvirni znanstveni članek Opis: Critical behaviour in phase transitions is a resource for enhanced precision metrology. The reason is that the function, known as Fisher information, is superextensive at critical points, and, at the same time, quantifies performances of metrological protocols. Therefore, preparing metrological probes at phase transitions provides enhanced precision in measuring the transition control parameter. We focus on the Lipkin-Meshkov-Glick model that exhibits excited state quantum phase transitions at different magnetic fields. Resting on the model spectral properties, we show broad peaks of the Fisher information, and propose efficient schemes for precision magnetometry. The Lipkin-Meshkov-Glick model was first introduced for superconductivity and for nuclear systems, and recently realised in several condensed matter platforms. The above metrological schemes can be also exploited to measure microscopic properties of systems able to simulate the LipkinMeshkov-Glick model.
Ključne besede: magnetometry, quantum phase transitions, precision, measurements
Objavljeno v DKUM: 22.08.2024; Ogledov: 62; Prenosov: 10
Celotno besedilo (1,52 MB)
Gradivo ima več datotek! Več... |
3. Optical characteristics of directly deposited gold nanoparticle filmsJordi Sancho-Parramon, Tilen Švarc, Peter Majerič, Žiga Jelen, Rebeka Rudolf, 2024, izvirni znanstveni članek Opis: The manuscript presents the optical properties of directly deposited films of gold nanoparticles (AuNPs) prepared by the Ultrasonic Spray Pyrolysis (USP) technology. Four samples were produced, with AuNP deposition times on the glass substrate of 15 min, 30 min, 1 h and 4 h. The morphological characterisation of the deposited films showed that the size of the first deposited AuNPs was between 10 and 30 nm, while, with a longer duration of the deposition process, larger clusters of AuNPs grew by coalescence and aggregation. The prepared layers were characterised optically with Ultraviolet–visible spectroscopy (UV–vis) and ellipsometry. The ellipsometric measurements showed an increasingly denser and thicker effective thickness of the AuNP layers. The extinction spectra displayed a clear local surface plasmonic resonance (LSPR) signature (peak 520–540 nm), indicating the presence of isolated particles in all the samples. For all AuNP layers, the imaginary part of the parallel and perpendicular components of the anisotropic dielectric function was dominated by a central peak at around 2.2 eV, corresponding to the LSPR of isolated particles, and a high-energy shoulder due to Au interband transitions. It was shown that, as the density of particles increased, the extinction cross-section grew over the whole spectral range where measurements are taken. Thus, the response can be explained with an enhanced electromagnetic response between the AuNPs that can be connected to the increase in particle density, but also by the formation of clusters and irregular structures.
Ključne besede: optical characteristics, gold nanoparticles’ films, UV–vis, ellipsometry measurements
Objavljeno v DKUM: 28.05.2024; Ogledov: 124; Prenosov: 0 |
4. |
5. 1D battery electric vehicle thermal management system calibration and simulation based on measurements : magistrsko deloManja Umbreht, 2024, magistrsko delo Opis: Electric vehicles are developing at an increased rate due to electrification trends and are trying to achieve the comfort level of existing vehicles with internal combustion engines. In this thesis, we considered a battery electric vehicle, with which measurements were carried out. We created a complete vehicle model in GT Suite software based on available measurements and vehicle data. The model was used to simulate measured test cases. We described the calibration procedure of standalone models and the assembly of a complete thermal model of the entire vehicle. At the end we compared three simulated test cases with vehicle measurements. We concluded that the developed vehicle simulation model behavior fits well to the measured vehicle.
Ključne besede: 1D CFD, VTMS, energy consumption, measurements, battery electric vehicle
Objavljeno v DKUM: 22.04.2024; Ogledov: 203; Prenosov: 0
Celotno besedilo (6,01 MB) |
6. Measurement of the branching fraction and ▫$CP$▫ asymmetry for ▫$B \to \bar{D}^0 \pi$▫ decaysT. Bloomfield, Jyoti Prakash Biswal, Marko Bračko, Samo Korpar, Peter Križan, Rok Pestotnik, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek Opis: We measure the branching fractions and CP asymmetries for the decays B⁰ → D¯ 0π⁰ and B⁺ → D¯ 0π⁺, using a data sample of 772 × 10⁶ BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB e⁺e− collider. The branching fractions obtained and direct CP asym-metries are B(B⁰ → D¯ 0π⁰)=[2.70 0.06(stat) 0.10(syst)]×10−⁴, B(B⁺ → D¯ 0π⁺)=[4.53 0.02(stat) 0.15(syst)]×10−³, ACP(B⁰ → D¯ 0π⁰)= [+0.42 2.05(stat) 1.22(syst)]%, and ACP(B⁺ → D¯ 0π⁺) = [+0.19 0.36(stat) 0.57(syst)]%. The measurements of B are the most precise to date and are in good agreement with previous results, as is the measurement of ACP(B⁺ → D¯ 0π⁺). The measurement of ACP for B⁰ → D¯ 0π⁰ is the first for this mode, and the value is consistent with Standard Model expectations.
Ključne besede: branching fraction, hadronic decays, particle decays, mesons, CP violation, precision measurements
Objavljeno v DKUM: 17.08.2023; Ogledov: 364; Prenosov: 39
Celotno besedilo (506,19 KB)
Gradivo ima več datotek! Več... |
7. Processing of signals produced by strain gauges in testing measurements of the bridgesBoštjan Kovačič, Rok Kamnik, Andrej Štrukelj, Nikolai Ivanovich Vatin, 2015, objavljeni znanstveni prispevek na konferenci Opis: Practical example of signal processing from strain gauge, inductive transducer and total station measurements are used to illustrate the features of the bridge load testing measurements. FFT provides accurate representation of physical behavior for static and dynamic signals obtained when loading the bridge. As a reference measurement the signal from inductive transducer was taken. A static part of the load test was also geodetically measured and theoretically calculated. The results are comparable.
Ključne besede: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Objavljeno v DKUM: 12.07.2023; Ogledov: 445; Prenosov: 32
Celotno besedilo (500,43 KB)
Gradivo ima več datotek! Več... |
8. A microfluidic, flow-through, liquid reagent fluorescence sensor applied to oxygen concentration measurementDominik Gril, Denis Đonlagić, 2023, izvirni znanstveni članek Ključne besede: microfluidic, microfluidic sensing systems, capillary-based fluorescent chemical sensor system, fluorescent sensors, oxygen sensing, fluorescent decay time measurements, on-line liquid analysis, optical fibers, capillaries, liquid reagent
Objavljeno v DKUM: 31.05.2023; Ogledov: 550; Prenosov: 72
Celotno besedilo (4,68 MB)
Gradivo ima več datotek! Več... |
9. GNSS monitoring of geologically demanding areasBoštjan Kovačič, Boško Pribičević, Rok Kamnik, 2016, izvirni znanstveni članek Opis: Displacement research using the three-dimensional global navigation satellite system (GNSS) as part of geodetic monitoring is becoming the key investigation for establishing a cause-and-effect relationships model between external natural factors, on the one hand, and the criteria that describes the level of functionality and safety of the observed natural or artificial object, on the other, in cases of motion of an object in space and time. The main objective of the deformation analysis is to confirm the stabilities of the reference points of a geodetic network, which are used to determine the movements of the control points that are stabilized on the observed objects. The assumption about the stabilities of certain reference points must be based on reasonable grounds, underpinned by measurements and proven by numerical methods. This is one part of the results of the deformation analysis when determining the extent of the movements and deformations. To do this a transformation is used in which a comparison is made between the coordinates of the points for two separate epochs. On the basis of the estimated transformation parameters, possible movements can be concluded within the reference points, i.e., on whether the datum parameters have changed. After confirming the stability of the geodetic network the coordinate differences of identical points measured within the different time windows can be determined as displacements and/or deformations of an object. In this paper one viaduct was assessed through geology and tectonic activities and also a load test of the viaduct was performed. The viaduct is in a quite active region, but the load test showed that the bridge response to the load is as expected.
Ključne besede: geodesy, geotehnics, monitoring, GNSS measurements, geology, deformation analysis, geodetic network
Objavljeno v DKUM: 18.06.2018; Ogledov: 1784; Prenosov: 77
Celotno besedilo (630,78 KB)
Gradivo ima več datotek! Več... |
10. Measurement and interpretation of the small strain stifness of Boštanj silty sandGregor Vilhar, Vojkan Jovičić, 2009, izvirni znanstveni članek Opis: This paper presents measurements, and an interpretation of these measurements, based on the use of bender-element probes for Boštanj silty sand. The samples were prepared at different initial void ratios and isotropically compressed up to 5 MPa. The bender-element technique was used to determine the dynamic shear modulus ($G_0$) of the soils at very small strains. The multiple bender-element probes were shot at different excitation frequencies in order to increase the reliability of the measurements. The $G_0$ stiffness was determined by using three different techniques: a) the first-time arrival, b) the phase-change method and c) the cross-correlation method. The systematic differences observed between the $G_0$ values, calculated using the three techniques, are discussed. The variation of $G_0$ in the log$G_0$ - log$p'$ plane was evaluated for the Boštanj silty sand and compared with other sands.
Ključne besede: silty sand, triaxial testing, small strain stiffness, bender elements, time-domain and frequency-domain, measurements
Objavljeno v DKUM: 06.06.2018; Ogledov: 1194; Prenosov: 165
Celotno besedilo (706,26 KB)
Gradivo ima več datotek! Več... |
