Conference papers (RICE)
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Item Timepix4: Power Supply Topology Optimization(IEEE, 2025) Růžička, Ondřej; Burian, Petr; Kulhánek, Tomáš; Zich, JanThis paper describes the design of a power management system for the Timepix4 readout chip. The Timepix4, the latest generation of the Timepix family developed within the MEDIPIX collaboration at CERN, is a powerful readout chip for particle pixel detectors. It offers enhanced resolution with a matrix of 512×448 pixels and excellent timing performance with 195 ps time binning. However, this high performance comes with strict requirements for power supply stability and low-noise operation. The authors discuss these requirements in detail and propose several candidate solutions for optimal powering of the chip. Two of these solutions were practically implemented and tested. The evaluation is based on measurements of electrical parameters as well as the impact of the proposed power supply concepts on the actual performance of the detector.
Item A Compact and Wideband Wilkinson Power Divider Using Lowpass Microstrip Filters(IEEE, 2023) Jalalian, Hesam; Al-Anbagi, Haidar N.; Jahanbakhshi, Maryam; Almtrod, Abdalghfor Abdalghfar APower dividers are the most important tools in microwave systems such as mixers, frequency multipliers, and feeding networks in antennas. So far, in designing power dividers, various methods have been used to reduce the size and eliminate unwanted harmonics. In this paper, using a resonator structure and low pass filter, a Wilkinson power divider with I-shaped structure is designed, simulated, and fabricated. According to the results of the simulation, this structure has 6-harmonic elimination. The size of the designed power divider, due to the use of resonators, has dimensions of 0.06 × 0.07 λg2, which reflects a size reduction of 65% and indicates one of the advantages of this divider. The guided wavelength at the working frequency of the resonator is calculated at 0.97 GHz. This structure also has a relative working bandwidth of 42%, which indicates its wide operation band. The isolation value is −31 dB, which is another benefit of this power divider. This divider has been built and measured on the Rt-duroid 5880 substrate, where the responses from the simulation and real implementation have good match.Item Development of a Low Budget Solar Simulator for Testing the Solar Radiation Effects(IEEE, 2025) Hirman, Martin; Skarda, Jakub; Čengery, Jiří; Kučera, Tomáš; Steiner, FrantišekThis paper presents the development of a low-cost solar simulator designed for testing the effects of solar radiation on various materials and photovoltaic cells. The simulator aims to replicate the solar spectrum identified as AM1.5G, adhering to the IEC 60068-2-5 standard, while significantly reducing acquisition costs compared to commercially available devices. The construction utilizes light-emitting diodes (LEDs) as the primary light source due to their energy efficiency, long lifespan, and spectral adjustability. An optical simulation was conducted using Ansys SPEOS software to optimize the LED arrangement and ensure uniform spectral irradiance across a test area of 200mm×200 mm. The results indicate that while the simulator meets several spectral requirements, further modifications are necessary to improve radiation intensity and homogeneity. This research contributes to the accessibility of solar testing technologies for educational and research institutions with limited budgets.Item Reusing SMD Components on E-textiles: An Ageing Study by Combination of Corrosive Gases and Washing(IEEE, 2025) Hirman, Martin; Navrátil, Jiří; Benešová, Andrea; Steiner, FrantišekThe growing demand for sustainable practices in the electronics industry has led to the exploration of circular economy principles, particularly in e-textiles. This study investigates the feasibility of reusing surface-mount device (SMD) components integrated into conductive textile ribbons under conditions simulating real-life degradation. Using accelerated aging tests involving exposure to corrosive gases and washing cycles, we evaluated the durability of electrical connections and conductive paths. Results show that SMD components can be reused across multiple life cycles with minimal performance loss, while conductive ribbons exhibit degradation primarily during washing. Protective measures, such as seam-sealing adhesive tape, were effective against environmental pollutants but less so against detergent infiltration during washing. A novel remanufacturing process was employed to extract, clean, and reattach SMD components, demonstrating their viability for reuse without compromising quality. This research highlights the potential for sustainable etextile manufacturing by enabling component reuse and reducing electronic waste.Item Acoustic Monitoring of Partial Discharges: Differentiating Corona and Surface Discharges Using Ultrasonic Methods(IEEE, 2025) Pihera, Josef; Tureček, Oldřich; Balvín, Ondřej; Řeboun, JanThe measurement and monitoring of partial discharges (PD) have become increasingly important due to the rapid rise of new technologies that increase the frequency of PD occurrences in electrical equipment, where such phenomena were previously absent or limited. This effect directly impacts the lifespan and reliability of devices, raising the need for timely diagnostics for their detection. This study focuses on the detection of partial discharges using acoustic methods, with particular attention given to the use of ultrasonic microphones. The aim of this work was to analyze the acoustic emission signals generated by partial discharges, such as corona and surface discharges, and evaluate how their frequency spectra can be used to distinguish between these types of discharges.For the measurement of partial discharges, an ultrasonic microphone was used to record the acoustic signals generated by discharges in the tested materials. The signal was then processed using FFT analysis. This process provides a detailed overview of the frequency components of the acoustic emissions, which are characteristic of various types of partial discharges, such as corona and surface discharges for different materials. Key frequency bands were identified that correlate with the intensity and type of discharges, enabling their effective differentiation.Item Soutěže a kreativní úlohy v programování – inovace v zadávání úloh s nástupem umělé inteligence(Vysoká škola polytechnická Jihlava, 2025) Šroubová, Lenka; Kropík, PetrV předmětech Katedry elektrotechniky a počítačového modelování týkajících se programování, práce s výpočetními systémy a informačních technologií dlouhodobě vyučujeme s využitím autotestů, autodiagnostických testů i řádných testů. Využíváme k tomu systém Moodle. S nástupem umělé inteligence je třeba formulovat úlohy tak, aby student nemohl snadno najít odpověď. Prioritou začíná být, aby student vygenerovaný kód pochopil, porozuměl mu a upravil ho podle zadání. Samotné zadání příkladů z programování je nutno koncipovat kombinováním nejen reálných příkladů z praxe a úlohpropojených s jinými teoretickými předměty, ale i smyšlených příběhů. Motivace pro řešení úkolů je udržována formou semestrálních soutěží.
Item Diagnostický systém pro prediktivní údržbu elektrických strojů v rámci správy aktiv(Západočeská univerzita v Plzni, 2025) Leffler, Jan; Mokrá, Zdislava; Sláma, Pavel; Frána, Zdeněk; Trnka, PavelTento příspěvek představuje přístup založený na univerzálním, modulárním, škálovatelném a nákladově poměrně efektivním systému, který byl vyvinut speciálně pro menší provozy s nízkonapěťovými až vysokonapěťovými elektrickými zařízeními a stroji. Navrhované komplexní řešení umožňuje lokální, autonomní odhad zbývající životnosti i pravděpodobnosti poruchy v reálném čase prostřednictvím využití relevantních a originálních modelů propojených s příslušnými provozními diagnostickými signály. Tento systém tak nabízí možnost zvýšit provozní spolehlivost aktiv, snížit náklady na údržbu, řídit stárnutí a prodloužit životnost aktiv v rámci strategie prediktivní údržby.Item Behavior of Printed Conductive Structures Under Cyclic Load Realized by Direct-Write on a Textile Substrate(IEEE, 2024) Janda, Martin; Pretl, Silvan; Řeboun, JanIn this work, the stretchability of conductive tracks realized by Direct-Write on a thermoplastic polyurethane foil and laminated onto a textile, is analyzed. Samples of printed tracks are subjected to the mechanical cyclic stress test, and their electrical resistance is measured. Also, the mechanical properties of polyurethane foil as well as foil laminated onto a textile are measured. Results show, that the mechanical properties of a substrate play an important role in the electrical behavior of printed tracks, and therefore such stretchable systems should be always analyzed as a combination of its parts rather than just in terms of conductor properties.Item Comparison of Polarization Phenomena and Changes in Relative Permittivity in Mineral- and Ester-Based Nanofluids(IEEE, 2025) Mokrá, Zdislava; Trnka, Pavel; Michal, Ondřej; Hornak, Jaroslav; Sláma, PavelTwo different phenomena were observed in nanofluids with different oil-based fluids. While the relative permittivity increases in mineral oil-based oxide nanofluids, the opposite effect is seen in ester nanofluids. This paper describes the relaxation times and polarizations in pure oil samples and nanofluids, using Havriliak-Negami formula, a mathematical explanation of this phenomenon is attempted. An experiment was conducted where pure samples of the mineral oil Nynas Lyra, the natural ester rapeseed oil, and synthetic ester oil MIDEL 7131, and then their nanofluids with SiO2 additive were measured. The measurements were carried out using Broadband dielectric spectroscopy as a function of frequency and temperature.Item The fast neutron fluence and the activation monitor activity calculations using fine multigroup and continuous nuclear data(EDP Sciences, 2024) Lovecký, Martin; Tušlová, Pavlína; Smutný, VladimírThe fast neutron fluence and the activation monitor activities are routinely calculated with TORT deterministic code and BUGLE-B7 nuclear data library with 47 broad energy groups. The objective of the paper is to analyse options to improve reactor dosimetry transport calculations. There are two paths to improve reactor dosimetry calculations. Increasing geometry, angular and energy mesh size is applicable for TORT code while using newer nuclei data libraries is relevant for both deterministic and Monte Carlo codes. Two new calculation options (improved TORT and Monte Carlo MCNP6) were compared with the standard TORT calculation for VVER-440 Dukovany Unit 3 Cycle 31. The fast neutron fluence with 0.5 MeV threshold as well as activity of Fe, Ni, Ti, Cu, Mn and Nb monitors were evaluated. Standard TORT calculations were improved from S16P3 to S30P3 with three times finer axial mesh size, 120° core symmetry r-9 mesh size with 0.5° step and fine multigroup libraries VITAMIN-B7 with 199 neutron energy groups and ENDF/B-VII.1 with 200 neutron energy groups. Both EMDF/B and IRDFF activation cross sections were used The drawback of expanded mesh size is raised calculation runtime since TORT deterministic code is not parallelized and one calculation can require multiple weeks of CPU time An alternative option of using MCNP6 Monte Carlo code with continuous ENDF/B-VE.1 nuclear data with detailed 3-D geometry and pin-wise effective neutron source prepared by MOBY-DICK diffusion code reactor analysis was explored. It was found that using finer mesh size affects reactor dosimetry tallies less than the choice of nuclear data library. BUGLE-B7 and VITAMIN-B7 produce results typically within 1% difference. ENDF/B-VII.1 calculations with 200 neutron energy groups with TORT code are even in better agreement with MCNP6 calculations with continuous nuclear data libraries The largest differences of around 2% were observed between VITAMIN-B7 library based on ENDF/B-WO nuclear data and ENDF/B-VII.l library. Nuclear data library has larger impact on the results with up to 7 % difference between all 0.5 MeV fast neutron fluence calculations. The largest impact of nuclear data was observed for Mn(n,2n) monitor.Item Insulation for Rotating Machines Type II under Different Electrical Stress Conditions(IEEE, 2023) Zedan, Ousama Ahmed Abdalla; Haller, Rainer; Trnka, Pavel; Bärnklau, HansWith the increasing application of power electronic components in driving rotating machines, the electrical stress factors were significantly changed. This paper deals with the investigation of lifetime characteristics for insulation of type II rotating machines performed by breakdown measurement of pulse voltage at the different waveforms and rise time. The results were compared with those gathered at power frequency, using different time scaling parameters (number of pulses, effective time). It is found that the effective time of stress voltage provides a clearer perception to study the lifetime behaviour than the number of pulses, especially for comparing the effect of the different applied voltage waveforms on acceleration aging. The results indicate that the rise time of the pulse voltage is considered the main influence on the life of insulations, it leads to insulation failure in a lower time. Additionally, the effect of combined stress (electrical, thermal, mechanical) was studied by using a specially developed sample, which included the curved parts of windings. It was found that the most critical part of such "coil-windings"are those curved parts because they are stressed not only by higher mechanical but also by larger electrical field strength.Item Textile-based Antennas(Trans Tech Publications Ltd, 2025) Blecha, Tomáš; Handrejch, Jan; Radouchová, Michaela; Fröhlich, Adéla; Soukup, RadekThis article explores the design, fabrication, and application of textile-based antennas within the rapidly growing field of electronic textiles (e-textiles). Textile antennas are lightweight, flexible, and capable of seamless integration into garments, making them ideal for wearable electronics, Internet of Things (IoT) devices, and wireless sensor networks. In addition to facilitating wireless data transmission, they can serve as strain or deformation sensors for health monitoring and structural applications. A critical focus of the study is the development of reliable electrical interconnections between textile antennas and conventional electronic components, a challenge due to the incompatibility between standard electronic processes and textile substrates.Item Fabrication of Conductive Contact on Graphene Monolayers via Direct Ink Writing(IEEE, 2025) Šorm, Martin; Štulík, Jiří; Janda, Martin; Hamáček, AlešThis study investigates the formation of conductive contacts directly on graphene monolayers using direct ink writing (DIW). A glass substrate coated with a graphene monolayer was patterned using femtosecond laser ablation to create test lines with 200μ m width. Silver paste was deposited on the patterned graphene using DIW and then sintered at 60∘C in ambient air. The electrical properties of the resulting heterostructure were characterized by resistance, impedance, and current-voltage (I-V) measurements. The results showed that the silver-graphene interface exhibits ohmic behavior, with linear I-V characteristics and negligible effect on the conductivity of the graphene pathways. The measured resistivity values were consistent with lower values than theoretical expectations. This study demonstrates that the combination of femtosecond laser patterning and DIW provides an efficient approach to forming reliable electrical contacts for graphene-based devices, potentially as a pathway for applications in flexible electronics and sensors.Item Overview of Open-Source PoS Blockchain Platforms Using Smart Contracts for Energy Data Management(IEEE, 2025) Vinš, Martin; Noháč, KarelConsidering the completely new principles of the required cooperation of energy and financial operations in energy systems of the near future, their frequency, and the necessity of their protocol irreversibility, it is a new challenge for the energy industry to implement advanced algorithms of chained cooperatively authorized platforms for most of the new processes. Platforms that exist are often based on the blockchain principle. There are a variety of these platforms with different characteristics, making it difficult to assess them for a specific application in energy data management. This paper outlines the basic characteristics and possible criteria for selecting a suitable platform, focusing on three representative examples with which the authors have become more familiar.Item Influence of Load Impedance on PD Monitoring Sensitivity for High-Voltage Cable Lines(IEEE, 2025) Musil, Ondřej; Kettner, Finn A.; Steiner, Christoph; Shevchenko, Iaroslav; Kaltenborn, Uwe; Pihera, Josef; Polanský, RadekThe aim of this paper is to discuss the influence of the load impedance on the sensitivity of partial discharge (PD) measurements. The investigated circuit is based on coupling capacitors to provide a current path for PD signals during resonance testing of cables. The choice of an appropriate value for this capacitance is crucial. However, the overall impedance at the point of measurement is also determined by the inductance of the test circuit. The presented PD measurement method is a nonconventional system using high-frequency current transformers (HFCTs) to measure and localize PD sources along the cable system. The sensitivity of the whole measurement is, among others, strongly dependent on the impedance at the point of measurement. The results of simulations and effective measurements are analyzed and compared. The impact of the different parameters like parasitic capacitances and inductances in the measurement circuit on the accuracy as well as the sensitivity will be discussed in detail.Item Overview of Technologies for Wearable Textile Antennas Realization Based on Hybrid Threads(IEEE, 2025) Radouchová, Michaela; Handrejch, Jan; Fröhlich, Adéla; Blecha, TomášThis paper provides a comprehensive overview of fabrication technologies for wearable textile antennas based on hybrid conductive threads used during research at the University of West Bohemia. Emphasis is placed on comparing knitting, embroidery, and weaving in terms of flexibility, durability, integration potential, and suitability for specific wearable applications. The study also explores various interconnection technologies – including hot-bar welding, ultrasonic and thermo-compression bonding, and adhesive methods – that are critical for ensuring mechanical and electrical reliability. The integration of hybrid threads allows for the development of antennas that are lightweight, washable, and adaptable to body movements, making them suitable for applications in telemedicine, health monitoring, sports, and emergency services. The findings highlight the importance of selecting appropriate materials and techniques to meet the functional and comfort requirements of modern e-textiles..Item Space Charge Accumulation and Measurement Method for Insulation Materials(IEEE, 2025) Sláma, Pavel; Steiner, František; Trnka, PavelThis study focuses on the space charge accumulation in insulations. The specimens used in this study consist of a metal base with an applied insulator. Such specimen consists of copper base with a conformal coating. The conformal coating used is a commercially available acrylic resin-based coating. The pulsed electroacoustic (PEA) method was used for these measurements. The measured data gives information about the amount of space charge, its distribution and its effect on the electric field. Information about the ability of material to accumulate space charge is important as space charge can affect lifetime of insulating material, in this case of conformal coating. This in turn can give us information about the possibility of electric breakdown and partial discharges in conformal coating. The secondary aim of this study is to determine the suitability of used measurement method for the measurement of such samples.Item Temperature Profile Optimization for Vacuum Soldering of Components on Heat Sink(IEEE, 2025) Steiner, František; Hirman, Martin; Rous, Pavel; Wirth, VáclavEfficient heat dissipation is critical to the reliability and performance of modern high power density electronic systems. Direct soldering of power components to heat sinks minimizes thermal resistance, but traditional reflow soldering methods often result in the formation of voids in the joints, degrading thermal conductivity. This paper focuses on optimizing the temperature profile and vacuum process when soldering electronic components to heat sinks to minimize the occurrence of these voids. Key parameters such as temperature rise rate, time above liquidus (TAL), peak temperature, and most importantly timing and level of vacuum application are described. Using an experiment with different settings of the TAL parameters and vacuum timing, analysis was performed by X-ray inspection and quantification of the percentage of voids. The results show that the correct timing of vacuum application is a critical factor - the most effective vacuum application is after the solder has completely melted. Premature vacuuming leads to an increase in the number of voids, despite the extended TAL time. By optimizing the temperature profile and timing the vacuum correctly, a significant reduction in the occurrence of voids in the joint has been achieved. The paper presents an experimental approach and provides a instructions for achieving a high quality solder joint with minimal thermal resistance.Item Relative Resistance of PEEK and XLPE Insulated LV Cables in Nuclear Power Plants(IEEE, 2025) Kupilík, Tomáš; Prosr, Pavel; Pihera, JosefThis work focuses on high-temperature insulation materials for cables intended for use in nuclear power plants, emphasizing their stability and durability under harsh operating conditions. The introduction provides an overview of cable structures and insulation materials used in cable technology and describes diagnostic methods for analyzing their structural and phenomenological properties. In the experimental part, PEEK (polyetheretherketone) and XLPE (cross-linked polyethylene) insulated cables were selected for testing. The cables were subjected to accelerated thermal aging to simulate 60 years of operation in a nuclear power plant environment, with PEEK additionally undergoing radiation aging. The results show that XLPE exhibited significant degradation during thermal aging, while PEEK maintained stable structural and electrical properties throughout the tests.Item Mechanical Strength of Aged Solder Joints: Impact of Plasma Treatment(IEEE, 2025) Rous, Pavel; Krammer, Olivér; Medgyes, Bálint; Steiner, FrantišekThe reliability of solder joints, crucial for electronic assemblies, is influenced by factors including intermetallic compound (IMC) growth during aging and surface properties. This study investigated the impact of atmospheric plasma pre-treatment on the shear strength and IMC formation of aged (thermal aging and thermal shock) SAC305 solder joints on various PCB finishes (Cu, ImT, HASL, ENIG). Shear testing revealed that plasma treatment had a limited effect on mechanical strength under the applied test conditions. Fracture mode analysis indicated that failures predominantly occurred at the component’s lead metallization, suggesting that component quality was the limiting factor, masking potential effects of the plasma treatment applied to the PCB pads. Thermal shock aging was observed to be more detrimental to joint strength than thermal aging, particularly affecting the component-level integrity. IMC analysis showed expected growth with thermal aging. Plasma treatment had negligible impact on IMC thickness for ENIG finish, while an unexpected trend of reduced IMC thickness was observed for HASL finish, warranting further investigation. The study highlights the critical role of component robustness in reliability testing and suggests its potential to overshadow the influence of PCB surface treatments.
