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Wyniki wyszukiwania dla: EARTH FAULT LOOP IMPEDANCE MEASUREMENT
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Application of the short time Fourier transformation to the continuous frequency method of measurement of electrode impedance
PublikacjaPrzedstawiona została nowa metoda pomiaru impedancji elektrodowej. Wykorzystuje ona jako pobudzenie niestacjonarny sygnał napięciowy, którego częstotliwość jest liniową funkcją czasu. Zastosowanie transformacji STFT do analizy napięciowego sygnału pobudzenia i odpowiedzi prądowej umożliwia wyznaczenie widma impedancyjnego. Dokładność otrzymywanych wartości impedancji uwarunkowana jest wielkością okna i zastosowanej funkcji analizującej.
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A microcontroller system for measurement of three independent components in impedance sensors using a single square pulse
PublikacjaOpracowano nową metodę pomiaru w dziedzinie czasu i wyznaczania trzech składowych elementów modelu czujnika impedancyjnego oraz zaimplementowano ją w inteligentnym czujniku impedancji sterowanym 8-bitowym mikrokontrolerem. Metoda bazuje na pobudzeniu dzielnika napięciowego składającego się z rezystora pełniącego funkcję konwertera prąd na napięcie i z czujnika impedancji pojedynczym impulsem prostokątnym o czasie trwania T bezpośrednio...
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Electric shock hazard in circuits with variable-speed drives
PublikacjaThe conventional approach to electrical safety under fault condition in typical power systems considers earth fault currents of sinusoidal waveform and frequency of 50/60 Hz. However, in circuits with variable-speed drives, there is earth fault current flow with harmonics, and these harmonics influence the threshold of ventricular fibrillation. The paper presents earth fault current waveforms in circuits with variable-speed drives...
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Tripping limitations of residual current devices in photovoltaic installations
PublikacjaIn electrical installations with photovoltaic sources of energy, earth fault current may comprise alternating current component and direct current component. The waveform shape of this earth fault current mainly depends on the point of the fault and the properties of a photovoltaic power electronics converter. The waveform shape of the current influences operation of protection devices, especially tripping threshold of residual...
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Experimental verification of a new method of loop resistance testing in low voltage systems with residual current devices
PublikacjaA periodical verification of the effectiveness of protection against electric shock shall be performed in low voltage systems. The scope of this verification includes loop impedance/resistance testing. If a residual current device is installed in a tested circuit, this testing is problematic. A residual current device trips out during the test, because of the high value of measurement current. This precludes the execution of the...
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Determination of Mathematical Model Parameters of a Medium Frequency Transformer
PublikacjaThe paper presents the results of experimental studies of the medium frequency transformer. The object of the research was a prototype of a single-phase transformer with a core made of ferrite I-core elements and windings made of Litz conductors. The research was carried out to determine the parameters of the transformer's mathematical model. The scope of the tests included determining the magnetic hysteresis loop and measuring...
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Broken Rotor Symptons in the Sensorless Control of Induction Machine
PublikacjaInverter fed sensorless controlled variable speed drives with induction machine are widely used in the industry applications, also in wind power generation and electric vehicles. On-line self diagnostic systems implementation is needed for early stage fault detection and avoiding a critical fault. Diagnostic algorithms in modern DSP-based controllers can operate simultaneously with control system functions. In the closed-loop controlled...
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Residual current devices in electric vehicles charging installations
PublikacjaThe main requirements of national regulations and international standards regarding protection against electric shock in electric vehicle charging installations are presented. The principles of using residual current devices (RCDs) in such installations are discussed. It is pointed out that RCDs are mandatory equipment for safe charging of electric vehicles. It is noted that the standards require the use of RCDs having an appropriate...
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State and control system variables sensitivity to rotor asymmetry in the induction motor drive
PublikacjaThe aim of this paper is to undertake analysis and comparison of the closed-loop and sensorless control systems sensitivity to the broken rotor for diagnostic purposes. For the same vector control system induction motor drive analysis concerning operation with the asymmetric motor, broken rotor fault handling and operation were investigated. Reliability, range of stable operation, fault symptoms and application of diagnosis methods...
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Impact of configuration of earth continuity conductor on induced sheath voltages in power cables
PublikacjaIn high voltage power cable systems a problem of induced sheath voltages exist. Due to these voltages electric shock and damage of non-metallic outer sheath of the cables may occur. Exposure to voltage of the outer sheath may be very high in case of earth fault with high value of earth current. In order to reduce induced sheath voltages an earth continuity conductor (conductors) along power cables is applied. Configuration of this...
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A method of self-testing of an analog circuit terminated by an ADC in electronic embedded systems controlled by microcontrollers
PublikacjaA new self-testing method of analog parts terminated by an ADC in electronic embedded systems controlled by microcontrollers is presented. It is based on a new fault diagnosis method based on on-line (i.e. during measurement), transformations of voltage samples of the time response of a tested part to a square pulse - onto localization curves placed in the measurement space. The method can be used for fault detection and single...
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Low-frequency tripping characteristics of residual current devices
PublikacjaFast development of various types of converters makes their utilization in industry and in domestic installations very common. Due to converters, an earth fault current waveform in modern circuits can be distorted or its frequency can be different than 50/60 Hz. Frequency of earth fault (residual) current influences tripping of residual current devices which are widely used in low voltage systems. This paper presents the behaviour...
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LabVIEW-based intelligent system of protection against electric shock for photovoltaic installations
PublikacjaEvaluation of shock hazard in installations with photovoltaic sources of energy is more complicated than in a conventional low voltage system. In case of earth fault in photovoltaic generators, that are connected to the AC power public grid, a composite waveform of earth fault current in the installation may occur. For composite waveforms, the safety criteria should be modified. The paper considers the effect of the composite waveforms...
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Self-Testing of Analog Parts Terminated by ADCs Based on Multiple Sampling of Time Responses
PublikacjaA new approach for self-testing of analog parts terminated by analog-to-digital converters in mixed-signal electronic microsystems controlled by microcontrollers is presented. It is based upon a new fault diagnosis method using a transformation of the set of voltage samples of the time response of a tested analog part to a square impulse into localization curves placed in a multidimensional measurement space. The method can be used...
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Earth wires currents calculation by tableau analysis
PublikacjaThe paper presents a new method to compute a phase-to-earth fault current distribution in overhead transmission line. The method is based on the tableau analysis of an unbalanced, multi-wire model of a transmission line. It allows for the calculation of current distribution in overhead earth wires along the transmission line. Additionally, it may be used to calculate currents in a tower’s earthing system as well as voltages over...
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Broken rotor bar impact on sensorless control of induction machine
PublikacjaThe aim of the research is analysis of the sensorless control system of induction machine with broken rotor for diagnostic purposes. Increasing popularity of sensorless controlled variable speed drives requires research in area of reliability, range of stable operation, fault symptoms and application of diagnosis methods. T transformation (Cunha et al.,2003) used for conversion of instantaneous rotor currents electrical circuit...
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A method of self-testing of analog circuits based on fully differential op-amps with theTCBF classifier
PublikacjaA new approach of self-testing of analog circuits based on fully differential op-amps of mixed-signal systems controlled by microcontrollers is presented. It consists of a measurement procedure and a fault diagnosis procedure. We measure voltage samples of a time response of a tested circuit on a stimulation of a unit step function given at the common-mode reference voltage input of the op-amp. The fault detection and fault localization...
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RCDs Tripping in the Range from DC to AC 50 kHz for Slowly Rising Residual Current
PublikacjaThe wide use of power electronic converters means that in many low-voltage systems earth fault currents containing components from DC to AC of various frequencies have to be taken into account. Due to the tendency to increase the modulation frequency in converters, components of higher frequencies may be in the order of several tens of kilohertz. Therefore, it is very important to verify the behavior of devices for protection against...
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Residual current devices in installations with PV energy sources
PublikacjaThe paper presents the principles of residual current devices (RCDs) application in photovoltaic (PV) installations. Provisions of standards in this regard are commented on, in particular, attention is drawn to the lack of obligation to use of RCDs in PV installations. The issue of the shape of the earth fault current and the level of leakage currents in such installations are discussed. These factors influence the selection of...
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A Simple-Topology Compact Broadband Circularly Polarized Antenna With Unidirectional Radiation Pattern
PublikacjaIn this letter, a geometrically simple, reflector-backed single-point-fed circularly polarized (CP) antenna with unidirectional radiation pattern is presented. The structure comprises a simple coplanar waveguide (CPW) feeding circuit with an open slot etched on one side of the coplanar ground. The enhanced CP bandwidth is obtained by combining the loop mode, the slot mode, and the asymmetrical configuration of the coplanar ground...
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Computer-aided Analysis of Induced Sheath Voltages in High Voltage Power Cable System
PublikacjaThis paper concerns the effect of configuration of high voltage power cables on induced voltages in their metallic sheaths. One, two or three cables per phase and phase sequence of the cables are considered. Computing of the voltages was performed for a normal operation and in case of earth fault. Various ways of the sheaths bonding are considered as well. Shock hazard and voltage stress of non-metallic outer sheath of cables are...
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Fast High-Impedance Spectroscopy Method Using SINC Signal Excitation
PublikacjaIn this paper the method of fast impedance spectroscopy of technical objects with high impedance (|Zx| > 1 Gohm) is evaluated by means of simulation and practical experiment. The method is based on excitation of an object with a sinc signal and sampling response signals proportional to current flowing through and voltage across the measured impedance. The object impedance spectrum is obtained with use of continuous Fourier transform...
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Investigation of the electrochemical behaviour of AA1050 aluminium alloy in aqueous alkaline solutions using Dynamic Electrochemical Impedance Spectroscopy
PublikacjaThe paper presents the electrochemical behaviour of aluminium alloy AA1050 in aqueous alkaline media in the pH range 14–8.5. Electrochemical study was applied in order to obtain comprehensive information on the mechanism and kinetics of the process of anodic dissolution of aluminium, supplemented by monitoring of surface topography using an electron microscope. The corrosion rate of AA1050 increases with increasing concentration...
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Using an IEEE1149.1 Test Bus for Fault Diagnosis of Analog Parts of Electronic Embedded Systems
PublikacjaThe new solution of a BIST called the JTAG BIST for self-testing of analog parts of electronic embedded systems is presented in the paper. The JTAG BIST consists of the BCT8244A and SCANSTA476 integrated circuits of Texas Instruments controlled via the IEEE 1149.1 bus. The BCT8244A is a scan test device with octal buffers, and the SCANSTA476 is a 12-bit ADC with 8 analog input channels. Self-testing approach is based on the fault...
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Programmable dynamically changing RC model for evaluation of Dynamic EIS methods and instrumentation
PublikacjaThe paper concerns the RC equivalent circuit of electrochemical cell with the impedance changed during the experiment. The model was constructed using the digital potentiometers controlled by the microcontroller. This solution allows to control the model impedance by the software means. By creating adequate changes of the impedance spectrum as a time function, the different impedance measurement method can be tested to find out...
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Nowa metoda obliczania rozpływu prądów zwarciowych w przewodach odgromowych linii wysokiego napięcia
PublikacjaReferat przedstawia nowatorską metodę obliczania wartości prądów płynących w przewodach odgromowych w czasie zwarć, pozwalającą na dobór przewodów odgromowych pod względem wytrzymałości cieplnej. Proponowana metoda charakteryzuje się większą dokładnością i większą uniwersalnością niż powszechnie stosowane metody, pozwalając tym samym na dobór przewodów odgromowych z mniejszym ryzykiem niepewności. Prezentowana metoda obliczeniowa...
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Analysis of thoracic regional impedance changes using PCA approach
PublikacjaA multichannel impedance and one lead electrocardiographic recording system has been developed. The impedance measurement unit is built using a four-electrode technique. It consists of a sinusoidal, 40 kHz, current source and five measurement channels. Circumferential current electrodes have been located at a neck and an abdomen. Voltagemeasurement disk electrodes formed five two-electrode measurement ports. The impedance change...
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Performance of DS-CDMA Radionavigation Receiver with Subsample Time Measurement Resolution in Various Environments
PublikacjaThis paper presents results of investigation of position estimation performance in TDOA radionavigation system with receiver containing code tracking loop with subsample time measurement resolution. Position estimation accuracy was evaluated using real signals from CDMA base stations, recorded during measurement campaigns in various environments: on sea, flat terrain and hilly terrain.
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Metrological analysis of an computerized system of protection against electric shock in circuits with variable speed drives
PublikacjaDrive systems, that can be operated at variable speed, are equipped with power electronics converters. This causes distortion of the earth current, and consequently the need to take into account the use of proper protective devices in relation to earth current harmonics. This paper presents a system for protection against electric shock in circuits with power electronics converters and metrological analysis indicating the requirements...
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Demonstrator testera wbudowanego BIST dla układów w pełni różnicowych
PublikacjaPrzedstawiono demonstrator testera wbudowanego, przeznaczony do pracy na stanowisku dydaktycznym w laboratorium z przedmiotu Zaawansowane Metody Pomiarowe i Diagnostyczne. Na stanowisku studenci zapoznają się z technologią BIST (ang. Built-In Self-Test), która jest przykładem wdrożenia strategii projektowania dla testowania.
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Three modes of electrochemical impedance spectroscopy measurements performed on vanadium redox flow battery
PublikacjaThis article presents an innovative approach to monitor working redox flow batteries using dynamic electrochemical impedance spectroscopy, diverging from the commonly sequential impedance methods carried out under potentiostatic or galvanostatic conditions close to the open circle voltage. The authors introduce a fresh variation of dynamic impedance measurement that leverages an amplitude-modulated multi-frequency alternating current...
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Electrochemical Evaluation of Sustainable Corrosion Inhibitors via Dynamic Electrochemical Impedance Spectroscopy
PublikacjaFinding suitable measurement methods for the effective management of electrochemical problems is of paramount importance, particularly for improving efficiency in corrosion protection. The need for accurate measurement techniques specific to nonstationary conditions has long been recognized, and promising approaches have emerged. This chapter introduces dynamic electrochemical impedance spectroscopy as a novel advancement in electrochemistry...
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A concept of measurement system based on the Z-Wave standard
PublikacjaIn the paper a new concept of measurement system based on the Z-Wave standard is presented. This standard is dedicated to use mainly in home automation systems, but its properties enable to use it in dispersed measurement systems and support wireless communication between measurement nodes in a mesh-type network. In the paper basic metrological aspects of the Z-Wave standard and an example of impedance measurement system are discussed.
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The effect of current delay angle on tripping of residual current devices
PublikacjaPower electronics converters applied in domestic or similar installations may utilize current delay (phase) angle control to change the level of transferred power. Due to application of such types of converters, earth fault current in the installation may be strongly distorted. The current distortion level depends on a value of current delay angle. This delay angle also influences the tripping threshold of residual current devices....
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Uziemienia w zespołach elektrowni wiatrowych
PublikacjaW pracy jest omawiana problematyka budowy systemów uziemień na farmach elektrowni wiatrowych. Uziemienia poszczególnych elektrowni są wykorzystywane jako elementy systemu ochrony odgromowej oraz układu ochrony od porażeń otoczenia elektrowni wiatrowej. Farmy elektrowni są często umieszczane na gruntach o wysokiej rezystywności, co utrudnia realizację skutecznych systemów uziemień elektrowni. Trudność może napotykać zwłaszcza wykonanie...
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Polynomial analysis as a new way of describing dynamic impedance spectra – Differential and relative impedance spectra
PublikacjaModel measurements of an equivalent electrical system were carried out using the technique of Dynamic Electrochemical Impedance Spectroscopy. The measurement took the form of potentiodynamic changes imposed on the tested system. Using the possibility of continuous impedance measurements, an attempt was made to develop an original and innovative method of analyzing impedance spectrograms, which is termed polynomial analysis. As...
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Design and optimization of a novel compact broadband linearly/circularly polarized wide-slot antenna for WLAN and Wi-MAX applications
PublikacjaA novel topologically modified structure of a compact low profile wide-slot antenna for broadband applications is presented. The antenna comprises a modified E-shaped slot with unequal arm lengths in the ground plane, and a parasitic quasi-rectangular loop placed coplanar with the feedline. For exciting orthogonal modes with equal amplitude, a single-point feeding technique with an asymmetrical geometry of the coplanar waveguide...
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Noninvasive method for rotor fault diagnosis in inverter fed induction motor drive
PublikacjaThis article presents a proposal, simulation and experimental results of a noninvasive rotor fault diagnosis method for the inverter fed induction motor drive. Comparing to reported methods the proposed one does not require any load, rotor brake, slip, mechanical or electrical system physical modification e.g. machine disassembly and can be applied regardless the rotor speed measurement or estimation method.
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Novel fast non-linear electrochemical impedance method for corrosion investigations
PublikacjaThe paper presents a novel approach to corrosion rate monitoring using non-linear electrochemical impedance spectroscopy. The authors propose a new variant of non-linear impedance measurement using amplitude-modulated multi-frequency ac perturbation signal. It allows shortening of measurement duration so it is possible to monitor corrosion rate of the systems experiencing rapid changes. In this way a limitation resulting from lack...
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Tripping of F-type RCDs for sinusoidal residual current with superimposed smooth DC component
PublikacjaRecent trends in green energy development make that photovoltaics and electric vehicles are applied on an increasing scale. In both photovoltaic and electric vehicle charging installations, a significant value of DC component of the earth fault current may appear, which is a challenge, in particular, for commonly used residual current devices (RCDs). This paper presents results of the laboratory test on the operation of F-type...
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Samotestowanie toru analogowego ze wzmacniaczem w pełni różnicowym w elektronicznych systemach wbudowanych sterowanych mikrokontrole-rami
PublikacjaPrzedstawiono nową metodę samotestowania toru analogowego opartego na wzmacniaczu w pełni różnicowym w elektronicznych systemach wbu-dowanych sterowanych mikrokontrolerami. Bazuje ona na nowej metodzie diagnostycznej opartej na przekształceniu transformującym próbki odpo-wiedzi czasowej badanej części analogowej na pobudzenie "ujemnym" impulsem prostokątnym na wejściu Vocm na krzywe identyfikacyjne w przestrzeni pomiarowej. Metoda...
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Sensorless field oriented control for five-phase induction motors with third harmonic injection and fault insensitive feature
PublikacjaThe paper presents a solution for sensorless field oriented control (FOC) system for five-phase induction motors with improved rotor flux pattern. In order to obtain the advantages of a third harmonic injection with a quasi-trapezoidal flux shape, two vector models, α1–β1 and α3–β3, were transformed into d1– q1, d3– q3 rotating frames, which correlate to the 1st and 3rd harmonic plane respectively. A linearization approach of the...
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Implementation and Validation of Multisinusoidal, Fast Impedance Measurements in Atomic Force Microscope Contact Mode.
PublikacjaThis study presents a novel approach to impedance measurements. The methodology discussed is limited to contact in the sample-probe system under ambient conditions without the presence of electrolyte. Comparison with results of direct and alternating current measurements for well-defined metallic surfaces are made. In spite of idealization related to the type of contact examined, the proposed technique provides an improvement of...
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Multispectral impedance quality testing of coil-coating system using principal component analysis
PublikacjaThe task of quality checking of the coil-coated system was undertaken using impedance spectroscopy. In order to properly characterize the system the new impedance spectrum was calculated as an averaged result of 12 experimental spectra obtained from 12 different places of the sample at the same time of immersion in 3% of NaCl. The experimental spectra were recorded for a 24-h period at 1 h intervals between starting points of each...
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Multichannel self-optimizing narrowband interference canceller
PublikacjaThe problem of cancellation of a nonstationary sinusoidal interference, acting at the output of an unknown multivariable linear stable plant, is considered. No reference signal is assumed to be available. The proposed feedback controller is a nontrivial extension of the SONIC (self-optimizing narrowband interference canceller) algorithm, developed earlier for single-input, single-output plants. The algorithm consists of two loops:...
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A Comprehensive Analysis of Impedance of the Electrochemical Cell
PublikacjaA comprehensive impedance characteristics of two electrodes electrochemical cell has been pre sented. In this method a multisinusoidal current excitation signal is used. The change of potential of both the electrodes are all registered as a function of time. The proposed method gives the possibility of determining the impedance of both electrodes individually as well as the impedance of a twoelectrode system. Additional application...
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Localized impedance measurements of AA2024 and AA2024-T3 performed by means of AFM in contact mode
PublikacjaPurpose: The purpose of this paper is to present the results of an atomic force microscopy (AFM) based approach to local impedance spectroscopy (LIS) measurement performed on AA2024 and AA2024-T3 aluminium alloys. Design/methodology/approach: AFM-LIS measurements were performed ex-situ without the electrolyte environment, so in fact the electrical not electrochemical impedance was obtained. Findings: Relative local impedance values...
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Local electrochemical impedance spectroscopy in dynamic mode of galvanic coupling
PublikacjaA novel method that combines local electrochemical impedance spectroscopy and mapping in dynamicmode is proposed. Method was validated over two galvanic couplings, namely zinc/copper and cad-mium/copper. Impedance spectrum response for all measuring points was obtained by means ofsimultaneous implementation of selected range of frequencies. Proposed method allows the measure-ment in a more time-efficient manner, at the same time...
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Risk Analysis by a Probabilistic Model of the Measurement Process
PublikacjaThe aim of the article is presentation of the testing methodology and results of examination the probabilistic model of the measurement process. The case study concerns the determination of the risk of an incorrect decision in the assessment of the compliance of products by measurement. Measurand is characterized by the generalized Rayleigh distribution. The model of the meas-urement process was tested in parallel mode by six risk...
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Badania eksperymentalne rezonansowego przetwornika piezoelektrycznego typu "unimorph"
PublikacjaW artykule opisano badania eksperymentalne piezoelektrycznego rezonansowego przetwornika zastosowanego do pomiaru właściwości mechanicznych tkanek miękkich. Po krótkim wstępie w kolejnych punktach przedstawiono opis stanowiska pomiarowego oraz metody pomiaru odkształceń prototypów, przesunięć częstotliwości rezonansowej, impedancji elektromechanicznej i parametrów schematów zastępczych. W dalszej...