Martin Šíra

Martin Šíra
Czech Metrology Institute | ČMI · Department of primary metrology of electrical quantities

About

77
Publications
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585
Citations

Publications

Publications (77)
Article
Full-text available
A method for traceability to SI for ac voltage and current based on high performance digitizers is presented. In contrast to the existing thermal-based methods, the proposed method utilizes direct traceability to quantum-based waveforms via the use of Josephson voltage systems. This allows not only a simplification of the traceability chain and red...
Research
Full-text available
This Good Practice Guide is intended for both National and Industrial Metrology Laboratories who wish to invest in the development of a quantum standard for alternating voltage based on the Josephson effect. Dynamic electrical measurements are critical in many applications where the RMS (root mean square) value of an electrical signal does not prov...
Article
Full-text available
The energy efficiency of transportation is a crucial point for the rail and metro system today. The optimized recovery of the energy provided by the electrical braking can lead to savings of about 10% to 30%. Such figures can be reached by infrastructure measures which allow the recovery of the breaking energy that is not directly consumed by the r...
Article
Full-text available
Current standard EN 50463-2 indicates the tests and the requirements to be satisfied for an energy measurement system of a traction unit for railway applications. Some of these tests are to be done with several harmonics superposed on the rated voltage, respectively current. However, no calibration systems satisfying the standard requirements were...
Article
This paper describes a new four-terminal pair (4TP) digital sampling impedance bridge designed for the frequency range up to 1MHz and small impedances, such as shunts. The bridge is capable of comparing impedance standards of arbitrary ratios in a full complex plane from approximately 100kΩ down to 50mΩ, limited by the maximum achievable current 3A...
Article
A new method for the calibration of digitizers is proposed. This method uses the unique ability of the Josephson arbitrary waveform synthesizer to generate almost any waveform with high precision. A complex waveform has been prepared such that the gain of a digitizer, for different frequencies and amplitudes, was calibrated almost simultaneously. T...
Book
Full-text available
This Good Practice Guide is intended for both National and Industrial Metrology Laboratories who wish to invest in the development of a quantum standard for alternating voltage based on the Josephson effect. It gives a detailed description of the components required to construct a practical system as well as information on measurement techniques, u...
Technical Report
Full-text available
This document presents some considerations on the future inter-comparison of AC Programmable Josephson Voltage Standards (ACJVS) between two National Metrology Institutes. Namely Türkiye Bilimsel ve Teknolojik Araştirma Kurumu (TUBITAK) and Czech Metrology Institute (CMI) are considered as candidates.
Article
This paper describes a universal digital sampling setup for measurement of a complex voltage ratio. The setup was primarily designed for calibration of a phase angle error of current shunts, but it can be used for calibration of wide range of impedance standards in full complex plane. The setup allows calibration of impedances down to submegaohm ra...
Conference Paper
This paper describes digital sampling bridge for impedance measurement up to few tens of kHz in four terminal pair definition. It is primarily dedicated for low impedance measurements with comparison currents over 10 A however it can be used at least up to few tens of kΩ as well. Achieved uncertainty for near unity impedance ratio is few μΩ/Ω and t...
Conference Paper
This paper presents the evaluation of uncertainty components attributed to the algorithm used to estimate sampled signal parameters. The white noise in the signal will influence the standard deviation of the estimates while signal imperfections like harmonic distortions, interharmonics and even non-white noise would produce bias, leading to non-sta...
Conference Paper
Today a quantum Hall resistance standard (QHR) is realized in measurement setups with external supply of liquid helium. Operation costs due to helium prices and/or infrastructure needed to recycle evaporated helium gas are significant. The discovery of Quantum Hall effect in graphene made possible the measurement setup without an external supply of...
Conference Paper
This paper describes a simple, affordable and easily replicable 10 Ω resistance standard with calculable frequency dependence and time constant. The resistor is a bifilar type made from an enameled manganin wire. A time constant of 6.05 ns with uncertainty of 0.53 ns was calculated and verified by comparison with another calculable resistance stand...
Conference Paper
This paper describes an investigation of single junction thermal converters (SJTC) resulting in development of a primary standard of ac-dc current difference. Frequency characteristic of the primary standard was determined by special measurement methods (low frequency method, fast reversed dc) and by a lumped element model calculation. Comparison o...
Conference Paper
A new software toolbox QWTB is presented. It aims for aggregation of high-quality algorithms required for data processing of sampled measurements. Algorithms include frequency, amplitude and phase estimators, stability quantifiers, flicker calculator etc. The toolbox unifies and simplifies user interface of algorithms and an example for every algor...
Conference Paper
This paper describes digital sampling setup for measurement of complex voltage ratio. It was originally designed for calibration of a phase angle of current shunts. However later it was successfully used for comparison of various impedance standards up to 100 Ω, calibration of buffer transfer and also comparison of inductive voltage dividers (IVD)...
Technical Report
Full-text available
The report is on the definition of the requirements to use common software for the AC quantum voltage infrastructures. This involves monitoring and control of the AC quantum voltage standard (and automation of the measurements taken by the system under calibration (including RMS and direct sampling).
Article
Nonintrusive load meters (NILMs) with a load identification ability have been developed in several institutes and companies. All load identification algorithms (LIAs) have a common characteristic: load identification is based on the current waveform. A system for calibration and testing of meters with load identification ability is presented in thi...
Technical Report
Full-text available
This collection of training materials is based on slides presented during Workshop on AC Quantum Voltage Standards, held in Physikalisch-Technische Bundesanstalt, June 2015, in the scope of Joint research project ACQ-PRO (14RPT01)
Conference Paper
Full-text available
Josephson voltage standards are well established for use at dc and low-frequency ac voltages. The increasing demand i) to provide traceability for arbitrary waveforms, ii) to extend the range of use to higher frequencies, and iii) to improve the accuracy is being addressed in the project Q-WAVE, which is jointly funded by the European Union and the...
Conference Paper
Uncertainty analysis of a very simple sampling phase meter based on four parameter sine wave fitting is presented in this paper. An uncertainty of a sample time and a measured voltage is assigned to every sampled point and a total uncertainty of a phase difference is calculated by means of the Monte Carlo method. Results show the total uncertainty...
Article
Proposing the new SI prefixes is a very popular activity. However, its amusing nature often misleads the proponents. The aim of this paper is to provide them with as much rigorous reference as possible.
Article
This paper describes a new generation of cage-type ac/dc current shunts from 30 mA up to 10 A developed using a lumped circuit element model. Comparison of the calculated and measured values shows agreement better than 6 ?Ω/Ω in the ac-dc difference at frequencies up to 100 kHz.
Article
We report on the performance of a simple method, known as the reference step method, to build up the dc voltage scale of a source. The key advantages of this method are that it relies on equipment that is readily available in most high-level laboratories and can be fully automated. The Type A uncertainties achieved by this approach can be less than...
Conference Paper
This paper describes an open source software 1-phase digital sampling wattmeter based on the sampling card National Instruments 5922 and a set of voltage and current transducers with measurement ranges from 10 mA up to 20 A and from 12 V up to 560 V with ability to measure amplitude and phase of harmonics up to 10 kHz.
Conference Paper
This paper summarizes a comparison between two methods of building the voltage scale. The first one is the Reference Step Method developed at the Measurement Standards Laboratory of New Zealand. The second one is based on a binary potentiometer represented by the MI 8000/8001 instrument. Both methods were used to calibrate voltage ratios of a Fluke...
Article
The plasma pencil in liquids is a new device for the treatment of archeological artifacts. Plasma jets out from the pencil so that it makes radical changes in the conductivity and reactivity of liquids. An artifact is immersed in liquid and the plasma has a local and rapid effect on materials.
Article
A comparison of the 10 V Josephson array voltage standard of the Bureau International des Poids et Mesures (BIPM) was made with that of the Czech Metrology Institute (CMI), Czech Republic, in February 2011. For this exercise, option B of the comparison protocol was applied for the nominal voltage of 10 V. The BIPM provided a reference voltage for m...
Conference Paper
This paper describes a measurement system for DC characterization of high current shunts (below 0,1 Ω) in wide current level (from 5 A up to 100 A) built at CMI. DC characterization of such shunt includes direct resistance measurements, temperature coefficient and power coefficient measurement with uncertainties at ppm level.
Article
This paper describes current and frequency range extension of AC-DC current transfer difference measurement system in CMI which is now able to measure AC-DC current differences from 1 mA up to 10 A in the frequency range 10 Hz - 100 kHz.
Article
This paper describes the experiences and operational parameters of the Josephson voltage system cooled by closed cycle refrigerator produced by HYPRES, INC., USA and operated in CZECH METROLOGY INSTITUTE. The change of the cooling system was required and the new cooling system was implemented by SUPRACON AG. The overall increase in operational para...
Article
Automatic divider MI8000A is used to calibrate high precisions voltmeters up to ten volts. One have to use extender MI8001A to measure up to one thousand volts. As with software for the 8000A divider, calculation of uncertainties for this extender was corrected.
Article
The evolution of the luminosity of the coplanar barrier discharge in the single-filament mode was studied by the technique of cross-correlation spectroscopy and intensified high-speed CCD camera. For the first time 3D-spatially and temporally resolved investigations of the luminosity of second positive (at 337.1 nm) and first negative (at 391.5 nm)...
Article
Full-text available
This paper presents overview of new extension of use of the Binary Voltage Divider (BVD) based on Cutkosky principle for fully automated maintenance of voltage scale at positive and also negative voltages at range from 1 mV to 1200V. Existing Automated Potentiometer systems based on BVD principle are regularly used for maintenance of traceability f...
Conference Paper
Full-text available
The evolution of the luminosity of the coplanar barrier discharge in the single-filament mode was studied by the technique of cross-correlation spectroscopy. For the first time 3D-spatially and temporally resolved investigations of the second positive (at 337.1 nm) and first negative (at 391.5 nm) system of molecular nitrogen in this discharge type...
Article
Full-text available
The barrier discharge in the coplanar arrangement operating in a single-filament mode was studied spectroscopically. The evolution of the discharge luminosity was measured by the technique of cross-correlation spectroscopy. The 1D-spatially and temporally resolved luminosities of the first negative (at 391.5 nm) and the second positive (at 337.1 nm...
Article
A homogeneous atmospheric pressure dielectric barrier discharge was used for the surface modification of polycarbonate (PC). The discharge was generated between two planar metal electrodes, the top electrode was covered by glass and the bottom electrode was covered by a polymer sample. The discharge burned in pure nitrogen or in a mixture of nitrog...
Conference Paper
Full-text available
The evolution of the luminosity of the coplanar barrier discharge in the single-filament mode was studied by the technique of cross-correlation spectroscopy. The 2D-spatially and temporally resolved luminosity of the second positive system of molecular nitrogen (at 337.1 nm) was recorded. From these experimental data, the propagation of the cathode...
Article
In our previous work [1], we have demonstrated the possibility of observing the transition from a filamentary dielectric barrier discharge operation regime into the diffuse barrier discharge regime in air at atmospheric pressure. This work presents our attempt to reproduce the transition conditions in newly constructed transparent discharge reactor...
Article
The plasma device for fine hand manipulation called "plasma pencil" and diaphragm discharges is a special type of plasma nozzle generating high pressure non-isothermal plasma for different possible applications such as local treatment and cleaning of archaeological artifacts (metal, glass, ceramics) in liquid solution. In the contribution, the diag...
Article
Recently the technologies based on atmospheric pressure plasma sources become very promising tool for the control of surface properties of solids while the desirable bulk properties are kept. In this work the surface barrier discharge operated at atmospheric pressure was used for deposition of thin protective hydrophobic films from mixture of nitro...
Article
The atmospheric pressure glow discharge burning in nitrogen with small admixture of organosilicon compounds such as hexamethyldisilazane (HMDSN) or hexamethyldisiloxane (HMDSO) was used for the deposition of thin organosilicon polymer films at deposition temperatures up to 120 °C. The properties of the discharge were studied by means of optical emi...
Article
In this work, poly(ethylene terephthalate) (PET) cords were treated by an aborted arc discharge generated at atmospheric pressure. The PET cords were modified by plasma polymerization in a mixture of nitrogen and butadiene. The gaseous products arisen by decomposition of butadiene during the plasma polymerization were observed by UV–VIS emission sp...
Article
The objective of the present work is the development of a technique for the deposition of thin films, by means of an atmospheric pressure discharge, onto a pulp board surface, with the desired surface energy, permeability and wear resistant surface. The deposition of thin films was carried out by a surface barrier discharge at the atmospheric press...
Article
We present longitudinal emission diagnostics of the plasma channel in the special design of the plasma pencil - rf barrier torch discharge. This configuration has been developed for deposition of thin films on various surfaces. Using optical emission spectroscopy the spectroscopic quantities were determined as well as the longitudinal distribution...
Article
An atmospheric pressure glow discharge (APGD) was used for surface modification of polyethylene (PE) and polypropylene (PP). The discharge was generated between two planar metal electrodes, with the top electrode covered by a glass and the bottom electrode covered by the treated polymer sample. The discharge burned in pure nitrogen or in nitrogen–h...
Article
The plasma deposition at atmospheric pressure becomes a promising technology due to its economical and ecological advantages. The objective of the present work is to develop technique for deposition of thin films with desired surface energy, permeability and wear resistance on pulp board surface by means of discharge at atmospheric pressure. The...
Article
The results of statistical study of acid-base approach to the determination of the surface free energy are presented. Plasma enhanced chemical vapour deposition (PECVD) in low pressure RF discharge was used to prepare diamond-like carbon (DLC) coatings. The plasma deposited films were investigated by means of contact angle technique in order to det...
Article
The atmospheric pressure glow discharge was used for activation of polymer materials. The discharge was generated between two plane metal electrodes covered by a glass dielectric barrier. The discharge was ignited in pure nitrogen or in mixtures of nitrogen with hydrogen or nitrogen with ammonia. Studied polymers were polyethylene and polypropylene...
Article
In order to better understand the relations between the deposition conditions, the microstructure and hydrogen and/or nitrogen incorporation in polymeric films the thermal stability of coatings prepared in atmospheric pressure glow discharge was studied. The polymeric films were prepared from the mixture of hexamethyldisiloxane (HMDSO) or hexamethy...
Book
The book is a collection of 721 poems which reflect the breakdown of the postmodern poetry. The book is accessible in the Library of University Greifswald with the signature 558/KS 9999 S796 R4. Pages: 782.
Article
The atmospheric pressure glow discharge was used for the deposition of thin organosilicon polymer films. The discharge was burning in pure nitrogen used as a carrier gas with a small admixture of organosilicon compound - hexamethyldisiloxane (HMDSO) which was used as a monomer. The temperature of the substrate was elevated up to 120 °C to obtain ha...
Article
Full-text available
Plasma-enhanced chemical vapour deposition (PECVD) at atmospheric pressure becomes a promising technology. The objective of the present work is to develop technique for deposition of thin films with desired properties on paper surface by means of atmospheric pressure discharge. The depositions were carried out by the means of surface discharge at a...

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