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prof. Ing. Václav Papež, CSc.

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Review of electrochemical impedance spectroscopy methods for lithium-ion battery diagnostics and their limitations

  • DOI: 10.1007/s00706-023-03165-1
  • Link: https://doi.org/10.1007/s00706-023-03165-1
  • Department: Department of Electrotechnology
  • Annotation:
    Electrochemical impedance spectroscopy (EIS) is a measurement method widely used for non-destructive analysis and diagnostics in various electrochemical fields. From the measured dependence of the battery impedance on the frequency, it is possible to determine the parameters of various equivalent electrical circuit models of the battery. The conventional method of battery measurement using single-sine EIS is currently one of the most widely used methods for the analysis of lithium-ion batteries. However, its most significant disadvantage is the relatively long measurement time. For this reason, there is a growing demand for faster methods using fast-Fourier transform or pseudo-random sequences. A description of various EIS methods applications is provided in this paper.

Applicability of magnetic field for directed orientation of steel fibres in high-performing cementitious composites

  • Authors: Carrera, K., Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc., Konrád, P., Mára, M., Fornůsek, J., Kheml, P., Sovják, R.
  • Publication: The International Journal of Computational Methods and Experimental Measurements. 2022, 10(2), 131-145. ISSN 2046-0546.
  • Year: 2022
  • DOI: 10.2495/CMEM-V10-N2-131-145
  • Link: https://doi.org/10.2495/CMEM-V10-N2-131-145
  • Department: Department of Electrotechnology
  • Annotation:
    This paper explores the practical possibility of using a magnetic field to orient steel fibres in a fresh concrete matrix. This process leads to preferential orientation, which increases the desired mechanical properties of the hardened material. In general, this paper focuses on the technical aspects of the orientation process and identifies key areas, such as the strength and shape of the magnetic field, velocity of the sample’s passage through the magnetic field and viscosity of the materials. A proto-type orienting apparatus was constructed with different permanent magnet systems to evaluate their performance. An ultrasound gel and a cementitious matrix were used as a medium for the fibres. Numerical simulations were created to further understand the effects of the magnetic field’s strength and shape. The final orientation of the fibres in hardened concrete was evaluated using Q factor measurements, X-ray scans and bending tests. A sufficiently strong magnetic field can be used to orient fibres in fresh concrete.

Concrete lintels reinforced with steel fibres oriented by a magnetic field

  • DOI: 10.14311/AP.2022.62.0531
  • Link: https://doi.org/10.14311/AP.2022.62.0531
  • Department: Department of Electrotechnology
  • Annotation:
    This paper explores the possibility of applying the technique of magnetic orientation of steel fibres for manufacturing a concrete structural element of realistic dimensions, compared to small laboratory specimens. This technique could be a part of an answer to the current need for faster and automated production in the prefabrication industry. The examined specimens have dimensions of commonly used lintels in construction, 80 mm × 100 mm × 980 mm. The properties of specimens with magnetically oriented fibres are compared with same size specimens prefabricated conventionally. The orientation of fibres has been confirmed by Q-factor non-destructive testing method using a measuring coil. All specimens were tested with a four-point bending test. The specimens with oriented fibres show a significantly higher flexural strength, by 150 %, than specimens produced conventionally with the same volume of fibres.

Flexural strength of fibre reinforced concrete in relation to the angle of magnetically orientated fibres

  • DOI: 10.1051/matecconf/202236405017
  • Link: https://doi.org/10.1051/matecconf/202236405017
  • Department: Department of Electrotechnology
  • Annotation:
    This paper focuses on high-performance fibre-reinforced concrete and its flexural strength concerning fibre orientation. The orientation is provided by a fully controlled special device. This device can align the fibres in fresh concrete using a magnetic field. The specimens are inserted into the device at different angles to ensure different fibre orientations concerning the longer side of the sample, which corresponds to the direction of the main tensile stresses. Specifically, angles of 0 °, 30 °, 60 ° and 90 ° are tested and compared with each other and with reference specimens that are not exposed to a magnetic field. All samples are measured by a non-destructive method. This method was developed in our previous research and is based on measuring the quality factor Q of a measuring coil using an impedance meter. The samples are inserted into a measuring coil connected to an impedance meter. Flexural strength is obtained from the results of a threepoint bending test. All samples are tested until complete failure.

Magnetic properties of steel fibres commonly used in concrete

  • DOI: 10.1016/j.matpr.2022.04.134
  • Link: https://doi.org/10.1016/j.matpr.2022.04.134
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with measuring of magnetic properties of selected steel fibres commonly used in concrete. The results in relation to the possibility to orient fibres by magnetic field in fresh concrete are explained. The principle of the measurement setup used to obtain the magnetic parameters of the fibres is presented. The measurement setup is chosen to test fibres as they are with only the necessary mechanical shortening for fibres with shaped ends. Furthermore, the results for ten types of commonly used steel fibres from different manufacturers are presented and compared. For overview and control, the measurements on the fibres are supplemented by testing of known materials used in magnetic circuits.

Mechanical properties of high-performance concrete with steel fibres oriented by an electromagnetic field

  • DOI: 10.1061/(ASCE)MT.1943-5533.0004342
  • Link: https://doi.org/10.1061/(ASCE)MT.1943-5533.0004342
  • Department: Department of Electrotechnology
  • Annotation:
    In order to achieve better efficiency of dispersed fibre reinforcement in cementitious composites, manufacturers need to be able to directly control the fibre orientation. The magnetic orientation of fibres is an effective way to align fibres in the desired direction of the main tensile stresses and significantly improve the load-bearing capacity of the composite material. In this study, cementitious composites with different percentages of fibre reinforcement were subjected to the magnetic fibre-orienting process and their resulting mechanical parameters were examined. Also, a non-destructive method was used to evaluate the fibre orientation and volume. The flexural strengths and the capacity to dissipate mechanical energy were improved considerably compared to the reference non-oriented specimens. The non-destructive method was also reasonably accurate to predict these results.

Quality factor as a tool to measure concentration and orientation of ferromagnetic fibres in sample

  • DOI: 10.1016/j.matpr.2022.04.605
  • Link: https://doi.org/10.1016/j.matpr.2022.04.605
  • Department: Department of Electrotechnology
  • Annotation:
    Fibre-reinforced concrete is a modern composite material. Steel fibres are often used as scattered reinforcement in cement composites. We can achieve anisotropic final products by orienting the fibres, i.e. higher strength in the required direction. One of the ways, how to control the orientation of ferromagnetic fibre in composites, is a non-destructive method based on mutual induction. The advantage of non-destructive testing is, among other things, the possibility of application to fresh cement mixtures. This paper presents a fast and effective non-destructive measuring method of fibres orientation degree and fibre volume in cementitious composites. Furthermore, the measurement of fibres oriented at different angles and different fibre volumes is shown.

Simulations of the behaviour of steel ferromagnetic fibres commonly used in concrete in a magnetic field

  • DOI: 10.3390/ma15010128
  • Link: https://doi.org/10.3390/ma15010128
  • Department: Department of Electrotechnology
  • Annotation:
    The efficiency of fibre reinforcement in concrete can be drastically increased by orienting the fibres using a magnetic field. However, the parameters of such a field are not immediately apparent, as they depend on the specific fibre reaction to the magnetic field. In this paper, numerical simulations are conducted to study the mechanical torque acting on fibres placed in a magnetic field. The simulations are verified with an experimental setup as well as theoretical relationships. Ten different fibre types, both straight and hook-ended, are examined. The developed model can be successfully used to study the behaviour of fibres in a magnetic field. The fibre size plays the most important role together with the magnetic saturation of the fibre material. Multiple fibres show significant interactions.

Summary of findings on magnetic orientation of fibers in cement composites

  • DOI: 10.1016/j.matpr.2022.01.201
  • Link: https://doi.org/10.1016/j.matpr.2022.01.201
  • Department: Department of Electrotechnology
  • Annotation:
    This article summarizes the findings in newly developed technology – Magnetic Orientation of Fibers (MOF). New incoming technology MOF can easily and effectively reinforce concrete elements in a specific direction with ferromagnetic fibers using a magnetic field. Using this technology, it is possible to provide the required orientation of steel ferromagnetic fibers in a fresh mixture of High-Performance Fiber Reinforced Cementitious Composite (HPFRC) with the help of a magnetic field. This article aims to inform about the existing research that deals with this technology. It summarizes the experiments performed, the development of magnetic field generation devices and fiber alignment measurement equipment.

Electromagnetic Properties of Steel Fibres for Use in Cementitious Composites, Fibre Detection and Non-Destructive Testing

  • DOI: 10.3390/ma14092131
  • Link: https://doi.org/10.3390/ma14092131
  • Department: Department of Electrotechnology
  • Annotation:
    This paper deals with the description, measurement, and use of electromagnetic properties of ferromagnetic fibres used as dispersed fibre reinforcement in composite mixtures. Firstly, the fibres’ magnetic properties are shown, and a method of measuring the hysteresis loop of fibres is proposed. The results from the measurements are presented and a discussion of the influence of measured parameters on the fibres’ orientation in a magnetic field is performed. Furthermore, methods of non-destructive estimation, of their amount and orientation in the composite specimens, are discussed. The main experimental goal of this paper is to show the relationship between this non-destructive method’s results and the destructive flexural strength measurements. The method is sensitive enough to provide information related to fibre reinforcement.

New method for Si-wafer resistivity determination

  • DOI: 10.14311/ISPS.2021.021
  • Link: https://doi.org/10.14311/ISPS.2021.021
  • Department: Department of Electrotechnology
  • Annotation:
    Wafer resistivity is one of the most important parameters in production of Power Semiconductor Devices (PSD). This parameter is mainly responsible for achieving required breakdown voltage and other electric parameters. Proposal article describes principles and details of newly designed resonant method and new equipment according patent [1] and compares it with commonly known 4point method. This new method is based on resonant measurement of capacity and following calculation. New method exhibits comparable accuracy with 4point method and brings additional advantages.

Directed orientation of steel fibres in ultra-high-performance cementitious composite using the magnetic field

  • Authors: Lovichová, R., Takáčová, K., Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc., Mára, M., Fornůsek, J., Konrád, P., Sovják, R.
  • Publication: WIT Transactions on the Built Environment. Wessex: WIT PRESS, 2020. p. 39-49. High Performance and Optimum Design of Structures and Materials IV. vol. 196. ISSN 1746-4498. ISBN 978-1-78466-389-6.
  • Year: 2020
  • DOI: 10.2495/HPSM200051
  • Link: https://doi.org/10.2495/HPSM200051
  • Department: Department of Electrotechnology
  • Annotation:
    Ultra-high-performance fibre-reinforced cementitious composites are one of the key industries in the field of concrete technology. Thanks to their exceptional mechanical properties and significantly improved ductility, they are widely used for various special applications such as defensive and protective structures. In composite materials, it is desirable to place the reinforcement where it is needed and in the direction, it is needed. In fibre-reinforced cementitious composites, this orientation is possible through a magnetic field. In the framework of this study, a prototype device for controlled fibre orientation in a cementitious composite was developed. Mixtures of both cementitious composite and ultrasound gel having similar rheological properties to the cementitious matrix were tested. It has been observed that is possible to control the orientation of the steel fibres and direct the fibres in the desired direction by employing an electromagnetic field.

Optimization of a photovoltaic LiFePO4 battery charger

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 11th International Conference Biosystems Engineering. Tartu: University of Tartu, 2020.
  • Year: 2020
  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes the analysis and construction of an autonomous photovoltaic system for charging a LiFePO4 battery. The system is optimized for available components and their pricing to achieve a minimum battery charging time. The efficiency of the power transmission from the photovoltaic generator to the terminals of the charging battery, when they are directly inter-connected, is compared to the efficiency of conventional chargers with a DC/DC converter controlled by the “Maximum Power Point Tracking” algorithm.

Radiofrequency and Microwave Dielectric Properties of Plasma Sprayed and Annealed Thick Layers of Titanium Dioxide

  • DOI: 10.1007/s11666-020-01065-y
  • Link: https://doi.org/10.1007/s11666-020-01065-y
  • Department: Department of Electrotechnology
  • Annotation:
    Titanium dioxide (TiO2) was plasma sprayed using a high feed-rate spray system with hybrid water– argon stabilization torch (WSP-H). TiO2 powder agglom- erated from nanometric particles was used as the feedstock. The produced coating had thickness over 4 mm, to be comparable with bulk ceramic bodies. The deposit was removed from the substrate and annealed in air to reoxidize the oxygen deficient as-sprayed titania and to obtain material with a proper dielectric behavior. Besides the microstructure studies, radiofrequency dielectric spec- troscopy and microwave dielectric spectroscopy were in the focus of investigation. The approach to annealing of an extremely thick coating is studied: The significance of annealing of a large-area thick coating is discussed, as the role of grain interior and grain boundaries in the charge transport is influenced. Relative permittivity 94 and the Q*f product 12,800 GHz were reached at frequency 4 GHz, whereas the frequency response under 1 MHz was mapped continuously and the values (i.e., low and stable loss tangent) confirmed that a sprayed and air-an- nealed TiO2 is able to approach or also overperform dielectric parameters typical for TiO2 sintered bulk.

Capacitors with Metallized Electrodes Degradation Model

  • Department: Department of Electrotechnology
  • Annotation:
    Capacitors with Metallized Electrodes Degradation Model Lifetime prediction, testing and measurement of film capacitors parameters

Effective control and battery charging system of an island PV power plant

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Agronomy Research. 2019, 17(special issue 1), 1181-1190. ISSN 1406-894X.
  • Year: 2019
  • DOI: 10.15159/AR.19.122
  • Link: https://doi.org/10.15159/AR.19.122
  • Department: Department of Electrotechnology
  • Annotation:
    The paper presents a new concept of an autonomous PV power plant regulatory system with LiFePO4 batteries, which was functionally verified. The hardware system is significantly simpler and more operationally reliable. It also shows higher efficiency and lower acquisition costs than conventional commercial systems. The proposed control system was optimized for charging a multicell battery by PV electric energy. The system automatically maximizes the power supplied by the photovoltaic source and minimizes the power loss caused by balancing the individual cell charging processes. The problem of charge balancing is solved without the balancers. Battery cells are recharged from the separate converters supplying the PV power. The converters are controlled to observe a LiFePO4 battery charging mode while controlling the photovoltaic generator (PVG) load resistance based on an MPP monitoring. PVG power is not supplied to the charged cells, which are in this way protecte from overcharging. The entire PVG power is fed to the cells to be charged. The transmission from the converters is controlled in order not to exceed the voltage and current limits at the terminals and to minimize the actual voltage deviation from the control voltage at the PVG output. The control voltage is generated as an MPP voltage approximation according to the load characteristics and the actual PVG operating conditions.

Analysis of the Measuring Circuit for the OCVD Method

  • Department: Department of Electrotechnology
  • Annotation:
    The article describes the analysis of a possible influence of a measuring circuit on the results of the OCVD method. The influence of further junction parameters on effective carrier lifetime measurements is evaluated, which has not been currently monitored by the OCVD method. Then the influence of the exciting current generator, exciting current waveform and parasitic properties of the generator is searched. A especial emphasis is given on the impedance matching between an analysed PN junction and an evaluating part of a measuring circuit. A simulation algorithm expressing the processes both in the tested junction and measurement circuit was found. The measuring system was implemented in several variants and typical measurements were carried out. For experimentally determined parameters, the simulations, whose results showed a good compliance with the results of the experiments, were performed.

Battery capacity drop during operation

  • DOI: 10.15159/AR.18.026
  • Link: https://doi.org/10.15159/AR.18.026
  • Department: Department of Electrotechnology
  • Annotation:
    A lithium-iron-phosphate (LiFePO4) battery is nowadays considered one of the best types of batteries. The paper deals with the evaluation of the drop in their capacity during operation. Based on the physical analysis of charging and discharging processes, a mathematical model of the battery capacity has been developed during its lifetime. The decrease in capacity during battery operation is evaluated according to the loss of active material, which gradually diminishes due to a number of different processes. The analysis of the loss of the active material is carried out, in particular, according to the depth of discharge, battery temperature, charging and discharging time, including the time when the battery is out of service. The tests were performed on the Winston Battery, Calb, Thunder Sky and Sinopoly batteries by cyclic discharging and charging at the 50%, 90% or 100% depth of discharge. Their real parameters were determined, compared to the model parameters and the parameters specified by the manufacturers and suppliers. Two automated systems were used for testing. During the test, in the tested battery with several cells, charging and discharging by a constant current were carried out automatically. Operating parameters of the tested battery were continuously scanned, recorded and evaluated by the control computer. The capacity curves during the battery operation, determined by the type of models, were compared with the results of long-term real battery tests.

Capacitive frost depth indicator

  • DOI: 10.15159/AR.18.062
  • Link: https://doi.org/10.15159/AR.18.062
  • Department: Department of Electrotechnology
  • Annotation:
    The depth of soil freezing, i.e., the depth at which water is frozen, is a significant factor in meteorology, as it affects many processes in agriculture, building, etc. Soil frost penetration is an important factor for overwintering organisms, but also for physical and chemical processes in soil, particularly for its mechanical properties. The depth of freezing is normally determined directly, i.e. mechanically, using a special soil freezing meter, i.e., frost-depth indicator, according to the process of water freezing in the probe. Another method lies in determining the soil temperature by the interpolation of the curves from the graph, as measured by soil thermometers according to the change in the resistivity of soil or water, when frozen. The principle of the frost-depth indicator function is to evaluate the temperature dependence of water permittivity, which decreases, when water is frozen, from r ~ 87 at 1 r ~ 3.2 at -1 typical for ice. The water permittivity is evaluated by a measuring capacitor, which is adapted into the shape of the frost depth indicator probe, whose dielectric is deionized water. During freezing, the capacity is reduced in this area. The capacity of the partially frozen probe is directly proportional to the length of its non-frozen section. The measuring capacitor is a part of the resonant circuit of the oscillator. The frequency of the oscillator varies with the capacity of the probe and is further evaluated. The achievable measurement accuracy is approximately 2% for the probe of a 1m length and in direct evaluation by an autonomous counter. For the computer evaluation, with the possibility to compensate the probe non-linearity, the measurement accuracy is approximately 0.5%.

Endurance LiFePO4 battery testing

  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes the battery testing system, in which their real parameters, comparable with the parameters indicated by the suppliers, are tested

Optimization of the balancer for LiFePO4 battery charging

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, doc. Ing. CSc, S.
  • Publication: Agronomy Research. 2017, 15(S1), 1141-1151. ISSN 1406-894X.
  • Year: 2017
  • Department: Department of Electrotechnology
  • Annotation:
    Optimized balancers, whose construction is described in th e paper, work on a principle of a linear feedback controller. They can work with a maximum charging current up to 20 A, they have very low dynamic resistance of about 1 mW, and are absolutely stable. Their properties are further compared both with previously used circuits and commercial circuits.

Target position determining in aeronautical issues

  • Authors: Žák, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Proceedings of the International Radar Symposium 2017. Bonn: Deutsche Gesellschaft für Ortnung und Navigation (DGON), 2017. ISSN 2155-5745. ISBN 978-3-7369-9343-3.
  • Year: 2017
  • DOI: 10.23919/IRS.2017.8008243
  • Link: https://doi.org/10.23919/IRS.2017.8008243
  • Department: Department of Electrotechnology
  • Annotation:
    This article discusses the possibilities of the location of aircraft via active and passive radiolocation systems. The next part is dedicated to location recording of the aircraft, which uses the general type of Radiolocation Warning Receiver by triangulation method and PG method. Then we examine the analysis of the measured data with the purpose of determination of the location of source radiotechnical signal, using the general calculation algorithm and map image. Finally, we check the relevance of the results via graphical analysis, which was based on line of sight and special software computing.

Automated measuring station for accumulator testing

  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes the design and implementation of the system allowing the testing of the lithium-iron-phosphate (LiFePO4) cell parameters during long-term loading. Manufacturers and retailers, in particular, accentuate their beneficial properties the possibility of charging and discharging by high currents, minimum influence of the discharge time on capacity, long durability. At the same time, their operational conditions are a lot more strictly defined than those for other types of accumulators.

High-speed switch based on MOSFETs

  • Department: Department of Electrotechnology
  • Annotation:
    This article describes both the design and construction of the switch that enables switching with a high di/dt rate and a special type of a shunt for measuring current. A designed circuit is based on a parallel connection of high power MOSFET transistors with independent drivers. Negative influence of parasitic inductions of transistor leads was analyzed. Film capacitor testing is based on applying a very fast discharging process. Current and voltage waveforms arising during the measurement are used to create an equivalent circuit of the capacitor.

Optimization of a solar power station with LiFePO4 accumulators

  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes the design and construction of an isolated solar power station supplying energy at weekends to a remote location. The system comprises two parts: A photovoltaic system generating electric energy in sunlight, and an accumulator accumulating energy to be permanently available and to be able to supply a peak power of several kW. The design of the system optimized with respect to maximum reliability, ease of operation and minimum purchase costs. The control circuits were therefore constructed by means of simple analog circuits

Capacitive methodes for testing of power semiconductor devices

  • DOI: 10.2298/FUEE1503495P
  • Link: https://doi.org/10.2298/FUEE1503495P
  • Department: Department of Electrotechnology
  • Annotation:
    Electrical capacity of power semiconductor devices is quite an important parameter that can be utilized not only for testing a component itself, but it can also be applied practically; e.g. in series-connected high voltage devices. This paper first analyzes the theoretical voltage distribution on the bases of the polarized p-n junction, as well as the size of capacity. The measurement of the voltage capacity dependence using the resonance principle is illustrated on the samples of 4kV and 6kV thyristors. The correspondence between theoretical estimate of the capacity, measured voltage capacity dependence based on the resonance principle and experimentally determined by injected charge proves the correctness of the applied procedures and assumptions.

Isolated Solar Power Station

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 14th International Scientific Conference Engineering for Rural Development Proceedings. Jelgava: Latvia University of Agriculture, 2015. pp. 458-465. ISSN 1691-3043.
  • Year: 2015
  • Department: Department of Electrotechnology
  • Annotation:
    The paper describes a design of a simple small solar photovoltaic energy system that has been realized for electric power supply of objects situated on a (far-away) remote site out of reach of the power line system. Output of this power system is designed in order to supply a week-end operation of a shooting range for a hunting association and an amateur transmitting station. This system delivers approximately 5 kWh during Saturday and Sunday, in months with minimum sunshine (since November to February) and up to 10 kWh in months with higher level of sunshine. The construction of the system is optimised regarding maximal reliability, service unpretentiousness and minimal purchase costs.

MEASUREMENT OF TIME BASE CHARACTERISTICS OF HIGH RESOLUTION DIGITIZERS

Non-linearity Diagnostics of Nominally Linear Components

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2015 12th International Conference on Telecommutications in Modern Satellite, Cable and Broadcasting Services. Niš: Faculty Electrical Engineering of Niš, 2015. pp. 323-326. ISBN 978-1-4673-7516-0.
  • Year: 2015

Transformer Short-time Overload Testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2015 12th International Conference on Telecommutications in Modern Satellite, Cable and Broadcasting Services. Niš: Faculty Electrical Engineering of Niš, 2015. pp. 327-330. ISBN 978-1-4673-7516-0.
  • Year: 2015

Complementary methods for a diagnostic evaluation of physical and electrical parameters of power silicon devices

  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with investigation physical and electrical parameters of power semiconductor devices. The samples of the diodes with reverse voltage exceeding 6 kV were used for the measurement of p-n junction capacity. Capacity of p-n junction has been evaluated according current pulse during a fast transient waveform of reverse voltage. Another way is presented as the evaluation of voltage dependence of dynamic capacity of reverse biased diode. These non-destructive measurements enabled to evaluate the following parameters: (i) the resistivity of initial bulk silicon used for the processing of wafers, (ii) so called critical intensity of an electric field, which can be used as a quality marker of final (capsulated) devices and is inherently connected with the quality of the used input silicon material; this critical intensity is also a quality indicator of high temperature diffusion processes.

Equipment for the automatic testing of power capacitors

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2014 29th INTERNATIONAL CONFERENCE ON MICROELECTRONICS - PROCEEDINGS. Piscataway: IEEE - Electron Devices Society, 2014. pp. 341-344. ISSN 2159-1660. ISBN 978-1-4799-5296-0.
  • Year: 2014

High sensitivity phase noise measuring equipment

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2014 29th INTERNATIONAL CONFERENCE ON MICROELECTRONICS - PROCEEDINGS. Piscataway: IEEE - Electron Devices Society, 2014. pp. 337-340. ISSN 2159-1660. ISBN 978-1-4799-5296-0.
  • Year: 2014

Influence of surface states on the reverse and noise properties of silicon power diodes

  • DOI: 10.1049/iet-cds.2013.0219
  • Link: https://doi.org/10.1049/iet-cds.2013.0219
  • Department: Department of Electrotechnology
  • Annotation:
    This contribution investigates transient degradation of reverse characteristics of diodes by means of a noise measurement. This effect appears immediately after external heating or after a long time on-state polarisation of diodes (without a significant temperature growth of the device in this case). Simultaneously with the reverse characteristics degradation, the noise power measured under a low voltage DC reverse bias is influenced. The first possible cause of these effects is connected with so called slow surface states (SSS). The SSS are caused by the presence of material process induced defects in the region of a p-n junction surface termination. SSS have fundamental impact on the reverse properties of diodes and their low frequency noise behaviour. The second cause is connected with so called volume structural defects (VSD). Their origin can be genetic (e.g. the presence of imperfection inside a silicon crystal) or they can be induced during technological processing. These defects are not repairable and under the reverse bias they will form so called hot spots that is, places with a local high current density. Rapid and operative measurements of the noise power can reveal latent instabilities of reverse characteristics invisible during a standard inspection process during the production.

Current Loading of Adhesive Joints Aged in Environment with High Humidity

  • Department: Department of Electrotechnology
  • Annotation:
    Electrically conductive adhesive with epoxy matrix and silver filler was used for forming of adhesive joints. The joints were at first aged at the humidity near 100 % for 300 hours. The joints were then loaded with the rectangular current pulses with the amplitude 10 A, 20 A and 50 A. The width of the pulses was 5 microseconds, the frequency 50 Hz. It was found that the pulses changed the joints resistance.

Frequency Compensated High Power Matrix Resistor Network

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2013 11th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services. Beograd: IEEE - Jugoslovenskog IEEE, 2013. pp. 497-500. 1.. ISBN 978-1-4799-0899-8.
  • Year: 2013
  • DOI: 10.1109/TELSKS.2013.6704426
  • Link: https://doi.org/10.1109/TELSKS.2013.6704426
  • Department: Department of Electrotechnology
  • Annotation:
    The special construction of power load consisting of many pieces of thick film flanged resistors, which are in serial parallel connected so that load had different impedance than individual resistors, or it can be loaded with a greater power than a single part.

Low Level Phase Noise Measurement Techniques

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 2013 11th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services. Beograd: IEEE - Jugoslovenskog IEEE, 2013. pp. 493-496. 1.. ISBN 978-1-4799-0899-8.
  • Year: 2013

Air-Conditioner Control System for Foodstuffs Storing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceedings of 15th Mechatronika 2012. Praha: Czech Technical University in Prague, 2012. pp. 161-164. ISBN 978-80-01-04987-7.
  • Year: 2012
  • Department: Department of Electrotechnology
  • Annotation:
    This article deals with design and realization of control system for foodstuffs air-conditioned storing. System was developed with regard to minimal demand on energy consumption. It controls the operation of ventilators ensuring the exchange of air with the outside environment according to temperature of outside environment and temperature inside of stock room.

Averaging for Control Programs of Active Filters

  • Authors: Brejcha, M., Hájek, J., Černek, P., Pígl, J., prof. Ing. Václav Papež, CSc., Ing. Karel Künzel, CSc., Žáček, J.
  • Publication: Proceedings of the 13th International Scientific Conference EPE 2012. Brno: VUT v Brně, Fakulta elektrotechniky a komunikačních technologií, 2012. pp. 323-328. ISBN 978-80-214-4514-7.
  • Year: 2012
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with issues of calculating average value of instantaneous active power in control programs of active harmonic conditioners (active harmonic filters). Common methods based on infinite impulse response (IIR) digital filters are not optimal in some cases. The reason could be the computational and memory complexity. The article describes the cases of instabilities of the IIR filters, which leads to malfunction of control program of active filter. The CIC decimator is presented as suitable substitution of IIR filters.

Influence of Intermetallic Compounds on RF Resistance of Joints Soldered with Lead Free Alloys

  • Department: Department of Electrotechnology
  • Annotation:
    During soldering process intermetallic compounds as a reaction between solder and substrate are created. Physical properties of those compounds are different to properties of solder and substrate. The influence of intermetallic compounds (IMC) on radio frequency resistance of soldered joint has been identified. Tested solders were lead free Sn-1Cu, Sn-4Ag and Sn-3.8Ag-0.7Cu and lead containing Sn-37Pb (all in weight percent). Samples were annealed up to 3000 hours at 150 °C to accelerated growing of IMC. Radio frequency measuring method has been developed and is described. Influence of IMC on resistance of joint is growing with growing frequency because IMC with slightly different resistivity to base solder is creating barrier to current. Resistance of joints has been measured up to 3 GHz.

Influence of surface states on reverse and noise properties of silicon

  • Department: Department of Electrotechnology
  • Annotation:
    This contribution investigates transient degradation of reverse characteristics of diodes. This effect appears immediately after external heating or after a long time on-state polarization of diodes (without significant temperature growth of the device in this case). Simultaneously with the reverse characteristics degradation, the noise power (measured under low voltage reverse bias) is influenced. Common factor (which acts on both reverse and noise properties of diodes) is connected with so called surface states. The slow surface states (SSS) are caused by presence of material process induced defects in the region of p-n junction surface termination. SSS have fundamental impact on reverse properties of diodes and their low frequency noise behavior. The kinetics of processes evoked by temperature heating of diodes is described in former study. Presented article extends interest also on changes induced by on-state polarization of diodes. Inherent connection between SSS on semiconductor-dielectric interface and reverse behavior of diodes has a fundamental importance for a good prognosis of function and reliability. Rapid and operative measurements of noise power can reveal latent instabilities of reverse characteristics (invisible during standard inspection process) in production.

Investigation of Flicker Noise in Silicon Diodes under Reverse Bias

  • DOI: 10.1016/j.microrel.2011.10.021
  • Link: https://doi.org/10.1016/j.microrel.2011.10.021
  • Department: Department of Electrotechnology
  • Annotation:
    This article analyses some connections between the reverse properties of silicon power diodes and their flicker noise under reverse bias conditions. It is shown that the presence of defects in the silicon surface near the pn-junction termination has a significant influence on both the reverse VA characteristics (RVAC) and the low-frequency power noise of diodes under reverse bias conditions. However, the inherent relationship between both effects becomes apparent only under special conditions and by the use of sophisticated measurements. The article presents a simple physical model, describing the behaviour and effect of surface structural defects on the silicon surfaces in connection with the reverse and noise properties of the tested diodes. The model identifies and consequently performs the mutual relationships with respect to the physical nature of the investigated defects. The most important practical contribution of this article is to identify a simple way to reveal latent defects of chip reverse properties undetected by the standard in-process inspection, and to rectify these defects by a simple operation process (e.g. chemical etching). This information has great importance for reasonable prognosis of devices' reliability and lifetime, especially before encapsulation and introduction on the market.

Very Low Noise DC Power Supply

  • Department: Department of Electrotechnology
  • Annotation:
    Abstract - All electronic equipment where large S/N ratio is requested for the signal processing is very sensitive on disturbances coming from power supplies. This is especially true for high accuracy measurement equipment. Then simple solution is to feed such equipment from accumulators or batteries; nevertheless, this brings problems with their servicing. This contribution presents the results of study of noise disturbance of laboratory power supply on high pure sine-wave signal source and describes a design of realized special power supply with minimum noise.

Bio-impedance Signal Processing using Adaptive Digital Filter

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 10th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting. Niš: University of Niš, 2011. pp. 261-264. ISBN 978-1-4577-2016-1.
  • Year: 2011

Bridge Symetric Crystal Oscillator

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 10th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting. Niš: University of Niš, 2011. pp. 597-600. ISBN 978-1-4577-2016-1.
  • Year: 2011

Issues of flicker noise measurements on power semiconductor devices

  • Department: Department of Electrotechnology
  • Annotation:
    Flicker noise is one of the most important quality indicators of electronic devices. Quality of passive elements is often evaluated according noise level, which is deeply affected by material ageing. Noise measurement can be used for lifetime prediction and probability of failures. Concerning semiconductor devices flicker noise is a criterion of used production technology. Influence of ageing is (contrary of passive devices) not so expressive. However, noise measurement allows to reveal latent defects of diode reverse properties that are unidentified by means of standard in-process inspection. Unlike other standard methods noise measurement requires perfect matching of analyzing circuit and investigated device. Used equipment and method deeply affect results of measurement.

Low-distortion Harmonic Signal Quality Testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO TC4 International Workshop on ADC Modelling, Testing and Data Converter Analysis and Design. Perugia: Universita degli Studi di Perugia, 2011. ISBN 978-1-61839-279-4.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    The paper desctibeed special methods for measuring of special signal source with extreme high spectral purity that are designed with higher resolution for ADC testing.

Power Wire-wound RF Resistor with High Linearity

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 10th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting. Niš: University of Niš, 2011. pp. 601-604. ISBN 978-1-4577-2016-1.
  • Year: 2011

Radio-frequency Solder Film Surface Resistance Measurement

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with solder film measurement using high frequency resonator. Measurement of surface resistance of a conductor that consists of a layer of solder that is applied to the conductive material was done on high frequency, in the range of 500-5000 MHz.

Special Harmonic Signal Generators for ADC Testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO TC4 International Workshop on ADC Modelling, Testing and Data Converter Analysis and Design. Perugia: Universita degli Studi di Perugia, 2011. ISBN 978-1-61839-279-4.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    This paper described the parameters of harmonic signal are analysed in contribution, which is needed for inverters testing and further a construction of a special generator with high spectral purity is described.

Using of buck-converter to provide quality of the electricity

  • Authors: Brejcha, M., prof. Ing. Václav Papež, CSc., Pokorný, L.
  • Publication: Workshop 2011. Praha: České vysoké učení technické v Praze, 2011. pp. 1-6.
  • Year: 2011
  • Department: Department of Electrotechnology
  • Annotation:
    This project deals with the solution of AC/ AC converter based on buck-converter circuit. The circuit has interesting features in AC circuits, which were hardly described before. First of all it doesn't need a rectifier for its run. The conversion is made direct from AC circuit to AC circuit. The distortion of input current can be removed by simple passive filters without need any complicated PFC. The output voltage can be also easy sinusoidal if it is wanted. The control of the converter is also very easy, because the switches work with static duty-cycle. Behavior of the converter is very similar to regulated transformer. That can be utilize to construct an active compensator cos(φ). Unfortunately there are some catches in construction of the converter. This article tries to describe all of the main features and problems of the AC buck-converter.

An evaluation of the influence of a magnetic field on a human subject with the use of bio-impedance

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: Journal of Physics: Conference Series. 2010, 2010(200), 122007/1-122007/4. ISSN 1742-6588.
  • Year: 2010

Contactless measurement of thin metallic films

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceedings Miel 2010. Niš: IEEE Electron Devices Society, 2010. pp. 111-114. ISBN 978-1-4244-7198-0.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    The contribution presents the measurement of thin films exploiting the change of complex coil impedance. A special algoritm, ensuring the explicit evaluation of the measuring, is used for determining the layer thickness or sheet resistance.

DC Power Supply with Very Low Noise

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO Symposium TC-4, TC-19 & IWADC Instrumentation for the ICT Area. Košice: Technical University of Košice, 2010. ISBN 978-1-61782-338-1.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    This contribution presents the results of study of noise disturbance of laboratory power supply on high pure sine-wave signal source and describes a design of special power supply with minimum noise, which was realized

Evaluation of the Influence of the Magnetic Field on a Living Tissue

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: 4th IMECO International Symposium on Measurement, Analysis and Modelling of Human Functions - ISHF 10. Praha: České vysoké učení technické v Praze, Fakulta strojní, 2010. pp. 152-156. ISBN 978-1-61738-984-9.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    The paper provides a practicable methodology for direct quantitative observation of the influence of a magnetic field on live tissue by means evaluation of vasodilatation effects using infrared thermography, bio-impedance measurement and plethysmography.

Investigation of Flicker Noise in Silicon Diodes under Reverse Bias

  • Department: Department of Electrotechnology
  • Annotation:
    This article analyses some connections between reverse properties of silicon power diodes and their flicker noise under reverse bias. Common (connecting) aspect of these different angles of view is technological production process. The article presents a simple physical model describing a behavior and effect of surface structural defects in connection with a reverse and noise properties of tested diodes. Model defines and consequently performs mutual relations with respect to physical nature of the investigated defects. An interesting output of the model is the possibility to identify energy level and density of investigated defects.

Non-linearity diagnostics for Conductive Adhesives

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO Symposium TC-4, TC-19 & IWADC Instrumentation for the ICT Area. Košice: Technical University of Košice, 2010. ISBN 978-1-61782-338-1.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    The contribution present measuring equipment for non-linearity diagnostics of conductive adhesives. The equipment measures non-linearity of 3 orders. The measured level of non-linearity is - 180 dB with respect to the actuating signal.

Non-linearity measurement of low resistances

  • Department: Department of Electrotechnology
  • Annotation:
    A method of non-linearity evaluation for low resistances by the use of determination of the level of intermodulation signals is described. The equipment can measure small resistances powered with current 2 A and an inherent signal to carriers ratio of 180 dB.

PHOTOVOLTAIC POWER SUPPLY FOR A DISTANT STANDPOINT

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 4th International Conference on Trends in Agricultural Engineering - Proceedings Paper. Praha: Česká zemědělská univerzita (ČZU), 2010. pp. 463-467. ISBN 978-80-213-2088-8.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    Contribution describes a small autonomic source of electrical power, which is used for continual power supply of a small radio relay terminal station. The station is placed on a hilltop in a distance about 1,5 km from the village. This source is realized as photovoltaic system, which consists of silicon solar cells, accumulators and control circuits. The parameters of the arrangement during one year of the operation are presented in conclusion of our paper.

Signal Generator with Minimal Distortion for ADC Testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO Symposium TC-4, TC-19 & IWADC Instrumentation for the ICT Area. Košice: Technical University of Košice, 2010. ISBN 978-1-61782-338-1.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    The contribution presents signal generator with minimal distortion. The frequency stability of the generator is in order of 10-6/day, the output power 1W, the value of SINAD is close to 120 dB and the total harmonic distortion under - 170 dB by using of linear narrow-band filter.

Sine -wave signal sources for dynamic ADC testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceedings Miel 2010. Niš: IEEE Electron Devices Society, 2010. pp. 291-294. ISBN 978-1-4244-7198-0.
  • Year: 2010
  • Department: Department of Electrotechnology
  • Annotation:
    The contribution presents the analysis of parameters of testing generators und the construction of special generators with a high signal purity. The total harmonic distortion of the generators is under -170 dB, the value of SINAD is close to 120 dB, the output power is 1W.

Teaching in Electromagnetic Compatibility

  • Department: Department of Electrotechnology
  • Annotation:
    Proposal publication is focused on EMC branch. Except "classical" chapters it is interested in legislation and economical aspects of EMC, in designing and introducing electrical equipment into operation. Authors were deeply interested in new term "fixed installation", that is defined in new EU directives for EMC. Due to the accent on actual legislation process this publication is the only one in our country.

Thermal evaluation of the quality of electrically conductive adhesive joints

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with electrically conductive adhesives and inovative quality estimation method based on thermal field evaluation. The resistance of joint heated by passing current can be roughly estimated by the used of temperature field picture.

Analysis of the Signal Network Non-Linearity in a Metrological Laboratory

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XIX IMEKO World Congress 2009 - Fundamental and Applied Metrology. Lisbon: Instituto Superior Técnico/Instituto de Telecomunicaçoes Portugal, 2009. pp. 1463-1468. ISBN 978-963-88410-0-1.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    This paper presented examples of measured intermodulation product levels on transmission lines components.

Characteristics of high voltage cables and motors by impuls transmission

  • Authors: Pavelka, J., prof. Ing. Václav Papež, CSc.,
  • Publication: XXXI. celostátní konference o elektrických pohonech. Praha: Česká elektrotechnická společnost, 2009. pp. 141-146. ISBN 978-80-02-02151-3.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    Contribution presents results of high frequency measurements on low voltage and medium voltage cables and motors. Bode diagrams and Nyquist diagrams are presented and real parameters are determined. The comparison with calculation results and with data sheet parameters is down.

Contactless Diagnostics of Thin Film Layers

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XIX IMEKO World Congress 2009 - Fundamental and Applied Metrology. Lisbon: Instituto Superior Técnico/Instituto de Telecomunicaçoes Portugal, 2009. pp. 1428-1433. ISBN 978-963-88410-0-1.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    Thin layer resistance measurement using the change of complex coil impedance is a contact-less method for conductive layer diagnostics.

Highly Pure Signal Generators

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 9th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services. Niš: University of Nis, 2009. pp. 526-529. ISBN 978-1-4244-4381-9.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    The special testing signal generators designed for a series of frequencies in the frequency band 0.5 to 20 MHz. The frequency stability of the generators is in the order of 10-6/day, the output power is 1 W, the value of SINAD is under - 130 dB.

Low Noise DC Power Supplies

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XIX IMEKO World Congress 2009 - Fundamental and Applied Metrology. Lisbon: Instituto Superior Técnico/Instituto de Telecomunicaçoes Portugal, 2009. pp. 809-814. ISBN 978-963-88410-0-1.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with conception of low noise DC power supplies.The available noise level is 1nV/ÖHz.

Measurement of Conductive Connections and Joints Using Current Noise Evaluation

  • Department: Department of Electrotechnology
  • Annotation:
    The article describes a system with current noise evaluation for joints and contacts quality determination.

Sine Wave Signal Sources for Testing High-Speed High-Resolution A/D Converters

Vasodilation Effect of Pulse Magnetic Field

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: International Conference on Magnetism 2009, Karlsruhe, Germany. Karlsruhe: Universität Karlsruhe, 2009. p. 200.
  • Year: 2009
  • Department: Department of Electrotechnology
  • Annotation:
    The influence of a magnetic field on human is monitored by a special system which enables quantitative monitoring and evaluation of the influence of a pulse magnetic field on a live organism by using of bio-impedance evaluation of vasodilatation effects.

Contactless Measurement of Thin Film Thickness

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: EUROSENSORS XXII 2008. Dresden: Eurosensors, 2008. pp. 276-280. ISBN 978-3-00-025217-4.
  • Year: 2008
  • Department: Department of Electrotechnology
  • Annotation:
    The paper described the using of an induction - coil as a thickness sensor of thin conductive layer. Thin film thickness is evaluated by non-contact method using the change of complex coil impedance.

Equipment for Contactless Sheet Resistance Measurement

Evaluation of the Influence of the Magnetic Field on Human by use of Bio-Impedance

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: 16th IMEKO TC4 International Symposium. Florence: University of Florence, Faculty of Engineering and Faculty of Economics, 2008. ISBN 978-88-903149-3-3.
  • Year: 2008
  • Department: Department of Electrotechnology
  • Annotation:
    This paper describes a system, which enables quantitative monitoring and evaluation of the influence of pulse magnetic field on a live organism by using of bioimpedance measurement.

Power MOSFETs Bias Voltage Temperature Stabilization

  • DOI: 10.1049/ic:20080213
  • Link: https://doi.org/10.1049/ic:20080213
  • Department: Department of Electrotechnology
  • Annotation:
    The article describes a development of system that automatically stabilizes operating point of the MOSFETs used in Radio Frequency Power Amplifier (RFPA) with output power approx 500 W. This device uses a micro controller based system for measurement of power MOSFETs temperature and generating output bias voltage.

Power voltage sources with sinusoidal wave shape

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with power supplay for laborator purposes with sinusoidal wave shape of supply voltage. The sources work on power network frequency with minimum disturbances in wide frequency range. Such sources can be used for EMC measurement of harmonics, conducted emissions and other accurate measurements. The supressing of disturbance signals by filters is mentioned too.

Reliability of Reverse Properties of Power Semiconductor Devices: Influence of Surface Dielectric Layer and its Experimental Verification

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B., Šámal, D.
  • Publication: Microelectronics Journal. 2008, 39(6), 851-856. ISSN 0026-2692.
  • Year: 2008

Sinewave Signal Sources for Testing High Speed High Resolution Analog-to-Digital Converters

Source for a Power Supply of Measuring Systems in Laboratory

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 16th IMEKO TC4 International Symposium. Florence: University of Florence, Faculty of Engineering and Faculty of Economics, 2008. ISBN 978-88-903149-3-3.
  • Year: 2008
  • Department: Department of Electrotechnology
  • Annotation:
    In the paper are evaluated properties of the concrete power supplies used in laboratory - AC power network, testing AC power supply, UPC power supply, DC/AC inverter and special sources with minimal distribution - inverter with harmonic output voltage and motor - generator power supply.

Statictical Analysis of the Serial Connected Diode Chain Under Reverse Bias Devices

  • Authors: Šámal, D., Kojecký, B., prof. Ing. Václav Papež, CSc.,
  • Publication: ISPS 08 Proceedings. Praha: České vysoké učení technické v Praze, 2008. pp. 243-247. ISBN 978-80-01-04139-0.
  • Year: 2008
  • Department: Department of Electrotechnology
  • Annotation:
    This articla deals with the reverse voltage distribution along a chain of large number serial connected power silicon diodes. Reverse properties of an individual diode can be affected by random influences of its production process.

Highly Pure Sine-Wave Signal Sources for ADC Testing

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 15th IMEKO TC 4 International Symposium on Novelties in Electrical Measurements and Instrumentations. Iasi: CERMI Publishing House, 2007. pp. 35-40. ISBN 978-973-667-261-3.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    It is necessary to keep at the disposition test signals with a high spectral purity for series measuring e.g. in the area of metrology or electronics. Commercial signal generators do not satisfy higher requirements in this area. Our contribution describes chances of the improvement of their quality while using of suitable filters. There is described the construction of a special generator with a high spectral purity of a signal.

Impedance of Adhesive Joints over Frequency Range 0.3 to 3 GHz

Influence of Magnetic Field on Bioimpedance Changes

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 13th International Conference on Electrical Bioimpedance and 8 th Conference on Electrical Impedance Tomography 2007. Berlin: Springer, 2007. ISSN 1727-1983. ISBN 978-3-540-73840-4.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    This paper describes a system which enables quantitative monitoring and evaluation of the influence of a pulse magnetic field on a live organism by using of bioimpedance measurement.

Influence of Magnetic Field on Human

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: Proceeding ISHF. Lisbon: Faculdade de Motricidade Humana, 2007, pp. 313-318. ISBN 978-972-735-145-9.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    A magnetic field effect on a human being has been monitored at the exposure of a part body by a strong pulse magnetic field. A pulse magnetic field, generated by a pseudo-random current, has been used for experimental exposures. A couple of Helmholz coils have been chosen as an applicator. The high-level of the flux density of used magnetic field was c. 60 mT. The influence of the magnetic field has been monitored by evaluations of the bio-impedance changes and by the blood pressure. The bio-impedance has been measured by use of RF signal with the frequency 75 kHz by four-point method on the forearm. The bio-impedance change is a measure of a vasodilatation effect during the cardiac cycle and affection of those effects by a magnetic field too. The blood pressure has been measured in brachial artery by using common semi-automatic cuff pressure gauge

Special Power Supply for Measuring Systems

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 15th IMEKO TC 4 International Symposium on Novelties in Electrical Measurements and Instrumentations. Iasi: CERMI Publishing House, 2007. pp. 487-491. ISBN 978-973-667-261-3.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The functions of measuring instruments and measured equipments are always affected by technical parameters of the electrical energy, which supplies apparatus and arrangements. Disturbing signals, which are spread by power line along the supply system or by the form of radiated electromagnetic waves, get through measuring circuits. The relevance of all effects grows up with the increasing of the accuracy and sensitivity of taken measurements. In this paper there are analysed parameters of typical sources that are used for power supply of measuring instruments in laboratory. There is described the construction of a special source with minimal distortion too.

Technological Aspects of Noise-suppressing Filter Design

  • Authors: Ing. Karel Künzel, CSc., prof. Ing. Václav Papež, CSc.,
  • Publication: PIERS 2007 Prague - Proceeding of Progress In Electromagnetics Research Symposium. Cambridge, MA: The Electromagnetics Academy, 2007. pp. 102-106. ISSN 1559-9450. ISBN 978-1-934142-02-8.
  • Year: 2007
  • Department: Department of Electrotechnology
  • Annotation:
    The noise suppression is up to date problem of power electronic devices like power sources, power converters etc. Paper deals with suppression of conducted disturbances. Main topic is the filter design and it's assembling from real devices with theirs real characteristics. Filter topology and device wiring are very important too. Paper calls attention to selected questions and proposes their solution.

The Difficulties of Noise-suppressing Filter Design

  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with miscellaneous aspects of noise-suppressing filter design and application, especially with posibility worsen or fully inhibit correct filter function.

Conditions of Temperature and Time Instability Occurrence of Reverse-Biased Semiconductor Power Devices

  • Authors: Kojecký, B., prof. Ing. Václav Papež, CSc., Šámal, D.
  • Publication: Microelectronics Journal. 2006, 2006(37), 269-274. ISSN 0026-2692.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with temperature and time instability occurrence of reverse-biased semiconductor power device.

Diagnostics of Selected Electrical Properties of Nature-Friendly Joining Materials

  • Department: Department of Electrotechnology
  • Annotation:
    Diagnostics of electrically conductive adhesive joints is shown. As for electrical properties the resistance, nonlinearity and noise are investigated.

Equipment for Measurement of Nonlinearity of Nominally Linear Components

  • Department: Department of Electrotechnology
  • Annotation:
    Nonlinearity of a nominally linear components is a significant parameter which informs about the difference of and investigated component from ideal one.Equipment is based on evaluation of intermodulation distortion.Experiment is focus on measurement of conductive adhesive joints.

Equipment for Noise Monitoring of Power Supply Units

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Applied Electronics 2006. Plzeň: ZČU Plzeň, 2006. pp. 137-140. ISBN 978-80-7043-442-0.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    Contribution describes the methodic of the measuring of low-frequency interfering signals on the output of power supplied.

Frequency Dependence of Impedance of Adhesive Joints

  • Department: Department of Electrotechnology
  • Annotation:
    Electrically conductive adhesives have in comparison with solders, significantily higher in-homogeneity of the structure and therefore electrical as well as mechanical properties of adhesive joints differ in comparison with that soldered ones. The joint impedances in the frequency range of 300 MHz to 3.4 GHz have been investigated.

Frequency Filters With High Linearity Design and Used Devices

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XIX-th Symposium Electromagnetic Phenomena in Nonlinear Circuits. Poznaň: University of Technology, 2006. pp. 121-122. ISSN 0332-1649. ISBN 83-921340-1-X.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The paper contains experieces about construction, realization and achievement record for high linear frequency filter.

Influence of Magnetic Field on Living Tissue

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XVIII-th IMEKO World Congress and Brazilian Congress of Metrology. Rio de Janeiro: IMEKO, 2006.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    This paper deskribes a system, which enebles quantitative monitoring and evaluation of the influence of a pulse magnetic field on a live organism by using of bioimpedance measurement. There are present results of performed experiments.

Nonlinearity Correction of a Pressure Sensor on the Basis of a Conductive Elastomer

  • Authors: Papežová, S., prof. Ing. Václav Papež, CSc.,
  • Publication: XIX-th Symposium Electromagnetic Phenomena in Nonlinear Circuits. Poznaň: University of Technology, 2006. pp. 173-174. ISSN 0332-1649. ISBN 83-921340-1-X.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with the calibration of the resistive sensor of mechanical pressure, the construction of the calibrating equipment and determinated dependencies of the resistance on the pressure.

OCVD Carrier Lifetime in P+NN+ Diode Structures With Axial Carrier Lifetime Gradient

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with OCVD Carrier Lifetime in P+NN+ diode structures with axial carrier lifetime gradient. Theoretically and experimentally is evaluated influence of carrier lifetime gradient on voltage courses during OCVD measurement and on the resulting carrier lifetime.

Reliability of Reverse Properties of Power Semiconductor Devices

  • Authors: Kojecký, B., prof. Ing. Václav Papež, CSc., Šámal, D.
  • Publication: ISPS 06 Proceedings. Praha: Ediční středisko ČVUT, 2006. pp. 183-187. ISSN 1751-858X. ISBN 80-01-03524-7.
  • Year: 2006
  • Department: Department of Electrotechnology
  • Annotation:
    Reliability of reverse properties of power semiconductor devices is an important condition for their practical applications.

Sine-Wave Signal Sources for Dynamic Testing High-Resolution High-Speed ADCs

  • Department: Department of Electrotechnology, Department of Measurement
  • Annotation:
    The paper deals with methods of a sine-wave signal generation for dynamic testing high-speed (1 MSa/s) to 100 MSa/s) ADCs with high resolution (14 to 20 bits). The techniques of noise and distortion measurement of spectrally-pure sine-wave signals are also discussed.

A Simple Technique for Measuring Signal Source Noise

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceedings of the 14th International Symposium on New Technologies in Measurement and Instrumentation. Gdynia/Jurata: Gdynia Maritime University, Faculty of Marine Electrical Engineering, 2005. pp. 57-60. ISBN 83-89786-37-0.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    Any practical oscillator has fluctuations in its amplitude and frequency. These fluctuations represent random amplitude modulation and phase jitter in the time domain.

Calibration Equipment for a Pressure Sensor on the Basis of a Conductive Elastomer

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceedings of the 14th International Symposium on New Technologies in Measurement and Instrumentation. Gdynia/Jurata: Gdynia Maritime University, Faculty of Marine Electrical Engineering, 2005. pp. 101-104. ISBN 83-89786-37-0.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    The equipment described in this paper has been developed on the basis of the requirement for a calibration pressure sensor based on the use of a conductive elastomer.

Close - to - Carrier Noise Measurement

  • Authors: prof. Ing. Václav Papež, CSc.,
  • Publication: Applied Electronics 2005. Plzeň: Západočeská univerzita v Plzni, 2005. pp. 265-268. ISBN 80-7043-369-8.
  • Year: 2005
  • Department: Department of Electrotechnology
  • Annotation:
    The close - to - carrier noise measurement can be provided by specially designed notch filter to suppress the dynamic range of sine - wave signal produced by high-quality signal generators.

Close-to-Carrier Noise Measurement

  • Department: Department of Electrotechnology, Department of Measurement
  • Annotation:
    The close-to-carrier noise measurement can be provided by a specially designed notch filter to suppress the dynamic range of sine-wave signal produced by high-quality signal generators. Filter design and experimental measurements at several commercial generators are presented in the paper.

Sine-Wave Signal Distortion Measurement at Higher Frequencies

  • Department: Department of Electrotechnology, Department of Measurement
  • Annotation:
    Noise and distortion measurement of sine-wave signal can be provided by a specially designed notch filter to suppress the dynamic range of sine-wave signal produced by high-quality signal generators. Filter design and experimental measurements at several commercial generators are presented in the paper.

Conditions of Temperature and Time Instability Occurrance of Reverse-Biased Semiconductor Power Devices

  • Authors: Kojecký, B., prof. Ing. Václav Papež, CSc., Šámal, D.
  • Publication: 7th International Seminar on Power Semiconductor. Praha: Ediční středisko ČVUT, 2004. pp. 191-196. ISBN 80-01-03046-6.
  • Year: 2004
  • Department: Department of Electrotechnology
  • Annotation:
    An investigation of the boundary states of power semiconductor devices is important with respect to their function reliability.

Harmonic Signal Generation with a High Spectral Purity for High Speed ADC Testing

  • Department: Department of Electrotechnology, Department of Measurement
  • Annotation:
    The paper describes the design and construction of the source of the testing signal with a high spectrl purity for the dynamic testing of the new high speed ADCs with more than 14-bits resolution. The system is based on a common sine-wave signal generator and the precise narrow-band band pass passive filter, and it performs a sine-wave signal with spectral purity higher than 130 dBc. It can be used for the dynamic testing of the ADCs up to 20-bits resolution.

Influence of a Magnetic Field on the Impedance of Living Tissue

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: IMEKO - International Measurement Confederation. Genova: IMEKO, 2004. pp. 247-250. ISBN 88-901344-0-2.
  • Year: 2004
  • Department: Department of Electrotechnology
  • Annotation:
    The use of a magnetic field for therapeutic purposes in medicine has been known since ancient times.

Noise Figure Measurement in Highly Mismatched Systems

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: 13th International Symposium on Measurements for Research and Industry Applications. Athens: IMEKO TC-4, 2004. pp. 635-640. ISBN 960-254-643-3.
  • Year: 2004
  • Department: Department of Electrotechnology
  • Annotation:
    This paper describes problems of measuring the noise figure when the noise figures are low and there is high mismatching of measurement system.

OCVD Carrier Lifetime in Diode Structutes with Axial Carrier Lifetime Gradient

  • Department: Department of Electrotechnology
  • Annotation:
    The OCVD (open circuit voltage decay) method is generally used method for determination carrier lifetime in structures of semiconductor devices.

Power Engineering Education and RF Properties of Power Devices and Converters

  • Department: Department of Electrotechnology
  • Annotation:
    The article deals with some problems related to application of contemporary power semiconductor devices.

RF Meesurements in Power Engineering

Degradation of Adhesive Bonds with Short Current Pulses

  • Department: Department of Electrotechnology
  • Annotation:
    Degradation of adhesive bonds powered by rectangular very short current pulses of the width of 1 microsec. and frequency of 1 kHz of high amplitude has been examined. The amplitudes of the pulses have been 5 and 10 A.

Electromagnetic Compatibility of SMPS

Energy Saving and Ecological Climatization Control System

  • Department: Department of Electrotechnology
  • Annotation:
    The contribution describes a self-contained air conditioner of the foodstore.The arrangement allows to observe an optimum thermic regime for the long-term storage of the foodstuffs during autumn,winter and spring.The thermic regime is regulated by using of the appreciable temperature capacity of the stock material.The power ventilation of the stock is controlled according to the variation of the outside temperature.Control system observes the inside and outside temperatures and controls the ventilation in order to keep the selected thermic regime.

Measurement of SMPS RF Conducted Emissions

Measurement of SMPS RF Conducted Emissions

Measurement System of RF Interferencies a Power Equipments

Measuring of Non-Linearity of Nominaly Linear Electronic Components and Networks

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: XVIIth IMEKO World Congress Metrology in the 3rd Millenium. Dubrovnik: IMEKO, 2003. pp. 832-836. ISBN 953-7124-00-2.
  • Year: 2003

Some Problems of EMC of Electric Drives

The Electromagnetic Compatibility of SMPS

  • Department: Department of Electrotechnology
  • Annotation:
    The paper deals with assurement, measurement and assessment of electromagnetic compatibility of switching mode power supplies.

The problems of RF conducted emissions measurement

Transient Effects on High Voltage Diode Stack under Reverse Bias

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B., Kožíšek, J., Hejhal, J.
  • Publication: Microelectronics Reliability. 2003, 43/4(274), 557-564. ISSN 0026-2714.
  • Year: 2003
  • Department: Department of Electrotechnology
  • Annotation:
    This article describes and analzses the fast transient processes that can occur during a local non-destructive breakdown in a circuit consisting of a serial connection of reverse biased high-voltage silicon diodes. Measurements of the reverse current-voltage characteristics of the individual diodes showed that a breakdown had occured. However, this phenomenon is very difficult to study when there are many diodes connected in series in a stack. A physicalmodel was therefore created to show the individual local breakdown in this case. The validity of the model was verified by means of circuit simulation of the process under investigation. The statistical significance of the process was considered with respect to the reliability and lifetime of a high-voltage diode stack.

Where starts and where ends power electrical engineering

Equpment for Therapeutic Use of Magnetic Field

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Elektroenergetika 2002. Praha: České vysoké učení technické v Praze, 2002. pp. 167-170. ISBN 80-01-02614-0.
  • Year: 2002

High Frequency Parameters of Power Cables

Transient Effects on High Voltage Diode Stack under Reverse Bias

  • Authors: prof. Ing. Václav Papež, CSc.,
  • Publication: Proceedings of the 6th International Seminar on Power Semiconductors. Praha: CTU. Publishing House, 2002. p. 181-187. ISBN 80-01-02595-0.
  • Year: 2002
  • Department: Department of Electrotechnology
  • Annotation:
    The existance of the non-destructive breakdown was observed at some measurements of reverse current-voltage characteristics of individual diodes. However, the study of this phenomenon is very difficult for many in series connected diodes in stack.

Transient Effects on High Voltage Diode Stack under Reverse Bias

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B., Kožíšek, J., Hejhal, J.
  • Publication: Proceedings of the 6th International Seminar on Power Semiconductors. Praha: Vydavatelství ČVUT, 2002. pp. 181-187. ISBN 80-01-02595-0.
  • Year: 2002

Development of the Course on Photovoltaic Systems

Elektromagnetické vyzařování laboratorních přístrojů se spínanými zdroji

Magnetotherapeutic Devices with Pulse Random Signal

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Applied Electronics 2001. Plzeň: Západočeská universita, 2001. pp. 158-161. ISBN 80-7082-758-0.
  • Year: 2001

The Diagnostic of Power Convertor Output Filters

The Overvoltage Suppression in A.C. Converter Drives

The Overvoltage Suppression on the long Cable with Matching Circuit

Advanced Thick Film Materials for High Density Metallization

EMC filters and their application

MEE - Aim, Tools, and Perspectives

Non-Linearity Measurement of Passive Components by Using of Intermodulation Distortion

  • Authors: prof. Ing. Václav Papež, CSc.,
  • Publication: XII. DIDMATTECH'99. Nitra: Univerzita Konštantína Filozofa v Nitre, 2000. pp. 130-133. ISBN 80-8050-283-8.
  • Year: 2000
  • Department: Department of Electrotechnology
  • Annotation:
    The new method of non-linearity measurement of nominal linear passive electronic components is described in the paper. The new method is compared with the method of third harmonic index measurement.

Properties and Limits of Material Systems for High-Density Metallization

RF Characteristics of Power Cables

Spectral Measurement on the System Frequency Converter-Cable-Induction Motor

Spurious Pulses in the Circuits of Electrical Equipment and Methods of their Elimination

  • Authors: prof. Ing. Václav Papež, CSc., Cetl, T.
  • Publication: Elektroenergetika 2000. Praha: České vysoké učení technické v Praze, 2000. pp. 98. ISBN 80-01-02238-2.
  • Year: 2000

Statistic Analysis Application for Some Electrical Parameters of the Silicon Power Diodes in Relation to Their Physical Design

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B., Konrádová, H.
  • Publication: ISPS'2000 Proceedings. Praha: České vysoké učení technické v Praze, 2000. pp. 169-174. ISBN 80-01-02195-5.
  • Year: 2000
  • Department: Department of Electrotechnology
  • Annotation:
    Statistic Analysis Application for Some Electrical Parameters and Reliability of the Silicon Power Diodes in Relation to Their Physical Design

Effects of Stirring During THM Crystal Growth

Grounding of cable shielding - evaluation of construction principles

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Urbánek, J.
  • Publication: XXVI. Celostátní konference o el. pohonech. Praha: Česká elektrotechnická společnost, 1999. pp. 171-175. ISBN 80-02-01292-5.
  • Year: 1999

Grounding of cable sielding - technology and quality

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Urbánek, J.
  • Publication: Diagnostika 99. Plzeň: ZČU FE, Odd. elektrotechnologie katedry el. strojů, 1999. pp. 19-21. ISBN 80-7082-544-8.
  • Year: 1999

Materials Engineering - the Influence of Force Fields on an Acceleration of Solidification Processes

MEE (Materials Engineering for Electronics)- Aim, Tools and Perspectives

  • Authors: Kousal, J., prof. Ing. Václav Papež, CSc., Venkrbec, J., Štětina, J., Ing. Josef Sedláček, CSc.,
  • Publication: Proceedings of the First International Conference on Advanced Engineering Design. Praha: České vysoké učení technické v Praze, 1999, pp. 115. ISBN 80-01-02055-X.
  • Year: 1999

Propagation of the Voltage Surge in Power Cables

Properties of Electically Conductive Adhesive Joints in Wide Frequency Range

Quality Evaluation of Grounding of Cable Screening

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Urbánek, J.
  • Publication: 22nd International Spring Seminar on Electronics Technology 1999. Dresden: Electronics Technology Laboratory of the Dresden University of Technology, 1999. pp. 347-349. ISBN 3-934142-00-1.
  • Year: 1999

Quality of Electrically Conductive Adhezive Joints

  • Authors: doc. Ing. Pavel Mach, CSc., Škvor, M., prof. Ing. Václav Papež, CSc.,
  • Publication: 22nd International Spring Seminar on Electronics Technology 1999. Dresden: Electronics Technology Laboratory of the Dresden University of Technology, 1999. pp. 1-5. ISBN 3-934142-00-1.
  • Year: 1999

Transient Impedance of Joint of Shielding Cable Sheath

  • Authors: Kuba, J., Urbánek, J., prof. Ing. Václav Papež, CSc.,
  • Publication: The 10th Conference on Microwave Techniques COMITE 1999. Prague: Czechoslovakia Section IEEE, 1999. pp. 146-148. ISBN 80-902417-3-5.
  • Year: 1999

A Wide-band Curent Sensor for Power Electronics

  • Department: Department of Electrotechnology
  • Annotation:
    A resistive current sensor with a wide frequency band (from DC to several MHz) for the use in power electronics. The sensor is constructed as a volume resistor (1-10 mOhms) with minimum parasitics

A Wide-band Current Sensor

  • Department: Department of Electrotechnology
  • Annotation:
    A resistive current sensor with a wide frequency band (from DC to several MHz) for the use in power electronics. The sensor is constructed as a volume resistor (1-10 mOhms) with minimum parasitics

Accelerated THM Crystal Growth of Semiconductor Materials

Design and Diagnostic of the Insulating Systems of Medical Devices

  • Authors: prof. Ing. Václav Papež, CSc., Kuba, J.
  • Publication: Dielectric and Insulating Systems in Electrical Engineering. Bratislava: STU v Bratislave, 1998. pp. 166-169. ISBN 80-227-1017-2.
  • Year: 1998

Materials Engineering - the Influence of Force Fields on an Acceleration of Solidification Processes

MHD and Mechanical Stirring in Semiconductor Crystal Growth

Superconducting Magnetic Bearing for High-Speed Engines

  • Authors: Vlček, J., Novák, J., prof. Ing. Václav Papež, CSc., Kuba, J., Galaš, I., Schustr, P., Vinš, M., Trubač, L.
  • Publication: Workshop 97. Praha: České vysoké učení technické v Praze, 1997, pp. 79-80.
  • Year: 1997

Testing of Avalanche Diode Characteristics

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B.
  • Publication: Workshop 97. Praha: České vysoké učení technické v Praze, 1997. pp. 951-952.
  • Year: 1997

The Influence of the Melt Stirring During the THM Crystallization on Crystal Growth for Optoelectronic Applications

  • Authors: Štětina, J., Kousal, J., prof. Ing. Václav Papež, CSc., Venkrbec, J.
  • Publication: Workshop 97. Praha: České vysoké učení technické v Praze, 1997, pp. 673-674.
  • Year: 1997
  • Department: Department of Electrotechnology
  • Annotation:
    Vliv míchání taveniny na růst definovaných krystalů pro optoelektronické aplikace při krystalizaci metodou THM.

THM and Mechanical Stirring in Semiconductor Crystal Growth

Monitoring of Ageing Process of Insulating Varnishes

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Workshop 96. Praha: České vysoké učení technické v Praze, 1996, pp. 633-634.
  • Year: 1996

Numerical Processing in Pulse Field Measurements

Power Avalanche Diodes - Test Equipment and Avalanches Behaviour Investigation

  • Authors: prof. Ing. Václav Papež, CSc., Kojecký, B.
  • Publication: Proceedings of the 3rd International Seminar on Power Semiconductors ISPS 96. Praha: České vysoké učení technické v Praze, 1996, pp. 95-103.
  • Year: 1996

Properties of Substrates for HTS Films

Substrates for HTS Films Elements

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Proceedings of the 19th International Spring Seminar on Electronics Technology ISSE 96. Budapest: Technical University, 1996. pp. 1-4. ISBN 963-420-505-4.
  • Year: 1996

A Study of the Dynamic Behaviour of Voltage Controlled Power Devices Extreme Conditions

High Temperature Superconductive Microwave Resonator

  • Authors: prof. Ing. Václav Papež, CSc., Kuba, J.
  • Publication: 3rd Japanese-Czech-Slovak Joint Seminar Aplied Electromagnetic. Praque: 1995. In proceeding. 1995, pp. 105-108.
  • Year: 1995

Magnetoterapeutický přístroj JAMAWA

  • Authors: Kuba, J., Stoulil, M., prof. Ing. Václav Papež, CSc.,
  • Publication: Workshop 95. Praha: České vysoké učení technické v Praze, 1995, pp. 71.
  • Year: 1995

Measurement of Dielectric Parametrs of Insulating Varnishes

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Proceeding of ISSE 95. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 1995, pp. 92-95.
  • Year: 1995

Methodology of Monitoring Correlation between Electric Properties Electric Insulating Varnish

Microwave Measurement of Insulator Properties at Very Low Temperatures

Microwave Quality Testing of Ceramic Materials

Microwave Quality Testing of Ceramic Materials

Novel Growth Methods of Optoelektronic Crystals Based on Animonides

  • Authors: Venkrbec, J., Kousal, J., Štětina, J., Fiksa, J., prof. Ing. Václav Papež, CSc., Rosická, V., Knobloch, V., Leitner, J., Kohout, J.
  • Publication: Journal of Thermal Analysis and Calorimetry. 1995, 43(2), 399-410. ISSN 0368-4466.
  • Year: 1995

Small Magnetotherapeutic Programmable Apparatus

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Stoulil, M.
  • Publication: Journal of the Japan Society on Applied Electromagnetics in Materials. 1995, 4(7), 415-421. ISSN 0919-4452.
  • Year: 1995

The Superconductive Microvawe Resonator

Dielectric Properties of Substrates for HTS Layers

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: CTU Seminar 94. Praha: České vysoké učení technické v Praze, 1994, pp. 135-136.
  • Year: 1994

Ecological Diagnostic of Leakages of Steam Turbines

  • Authors: Kuba, J., Mach, P., prof. Ing. Václav Papež, CSc.,
  • Publication: CTU Seminar 94. Praha: České vysoké učení technické v Praze, 1994, pp. 133-134.
  • Year: 1994

Experimental and Practical Activites in the Education of Electrotechnology

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc.,
  • Publication: Transaction of the Technical University in Košice. 1994, 3(1), 74. ISSN 0960-6076.
  • Year: 1994

Magnetoterapeutic Apparatus JAMAVA

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Stoulil, M.
  • Publication: Biomedical Engineering and Biotechnnology. Book of Abstracts. Praha: České vysoké učení technické v Praze, 1994, pp. 34-35.
  • Year: 1994

Novel Growth Methods of Optoelectronic Crystals

Properties of High Temperature Superconductor Layers at Very High Frequency

Small Magnetotherapeutic Programable Apparatus

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Stoulil, M.
  • Publication: Journal of the Japan Society on Applied Electromagnetics in Materials. 1994, 3(30), 8. ISSN 0919-4452.
  • Year: 1994

Small Magnetotherapeutic Programable Apparatus

  • Authors: Kuba, J., prof. Ing. Václav Papež, CSc., Stoulil, M.
  • Publication: Second Japanese-Czech-Slovak Joint Seminar on Applied Electromagnetics in Materials. Proceeding Abstracts. Kyoto: Doshisha University, 1994, pp. 178-181.
  • Year: 1994

Low Magnetic Field Sensor

  • Authors: Kuba, J., Stoulil, M., prof. Ing. Václav Papež, CSc.,
  • Publication: Thick and Thin Film Sensors. Wroclaw: Technical University, 1993, pp. 28-31.
  • Year: 1993

The Compensating Sensor

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S.
  • Publication: Proceeding of the Third International Symposium on Measurement and Control in Robotics. Session Cm. IV. Torino: Associazone Industriali Metallurgici Meccanici Affini, 1993, pp. 13-17.
  • Year: 1993

The Fibre Position Sensor

  • Authors: prof. Ing. Václav Papež, CSc., Papežová, S., Ryšánek, V.
  • Publication: Thick and Thin Film Sensors. Wroclaw: Technical University, 1993, pp. 36-39.
  • Year: 1993

Responsible person Ing. Mgr. Radovan Suk