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    Wyświetlanie 1-13 z 13
    Tytuł:
    Selection of optical to mography parameters for gas bubble shape analysis
    Autorzy:
    Rząsa, M.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/185491.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    bubble shape
    gas flow
    optical
    tomography
    two-phase measurement
    kształt bańki
    przepływ gazu
    tomografia
    pomiar dwufazowy
    Opis:
    An optical tomograph in which a tested object is illuminated from five directions has been presented in the paper. The measurements of luminous intensity after changing into discrete signals (0 or 1) in the detectors equipped with 64 optical sensors were subjected to reconstruction by means of the matrix algorithm. Detailed description of the measuring sensor, as well as the principles of operation of the electronic system, has been given in the paper. Optical phenomena occurring at the phase boundary while transmitted through the sensor wall and phenomena inside the measuring space have also been taken into account. The method of the sensor calibration has been analysed and a way of technical solution of the problem under consideration has been discussed. The elaborated method has been tested using objects of the known shape and dimensions. It was found that reconstruction of the shapes of moving bubbles and determination of their main parameters is also possible with a reasonable accuracy.
    Źródło:
    Chemical and Process Engineering; 2014, 35, 1; 19-33
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Single parallel stubs as broadband microwave phase shifters
    Autorzy:
    Rutkowski, Adam
    Powiązania:
    https://bibliotekanauki.pl/articles/220484.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    phase shift
    differential phase shift
    microwave phase shifter
    parallel stub
    instantaneous frequency measurement
    IFM
    Opis:
    Structures and characteristics of wideband small-size phase shifters made with the use of single parallel stubs are presented in this paper. The stubs can be short-circuited or open-circuited on termination. Such devices are well known, but are primarily used as components of filters or matching circuits. The novelty, then, comes from the establishment of simple, but helpful formulae, which enable to describe the insertion phase shift and differential phase shift of a line with short and open stubs connected in parallel. These equations can be very useful for designing complex microwave multi-ports. The results of simulations and measurements of the devices, which were designed and made, are shown herein. It was also proved that the presented device shave several usable operating frequency sub-bands, and that the differential phase shift values in the higher sub-bands are greater than those in the lower operating frequency ranges. Thanks to this, the described phase shifters can be used in more than one frequency sub-band. It was stated that in the conditions under analysis, larger phase shifts can be achieved using open-circuited stubs rather than short-circuited stubs. However, the phase shifters with shorted parallel stubs can operate in a wider frequency band.
    Źródło:
    Metrology and Measurement Systems; 2020, 27, 1; 91-102
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A concept of a passive radar with quadrature microwave phase discriminators
    Autorzy:
    Rutkowski, A. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/221600.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    passive radar
    instantaneous frequency measurement
    IFM
    microwave phase discriminator
    phase of noise signal
    Opis:
    Passive radar does not have its own emitter. It uses so-called signals of opportunity emitted by non-cooperative illuminators. During the detection of reflected signals, a direct signal from a non-cooperative emitter is used as the reference signal. Detection of electromagnetic echoes is, in present day radars, performed by finding the maximum of the cross ambiguity function. This function is based on the multiplication of the received signal and the reference signal. Detection of echoes by means of a quadrature microwave phase discriminator QMPD was proposed in the work as an alternative solution for ambiguity function evaluation. This discriminator carries out vectorial summing of the received and the reference signals. The summing operations in QMPD are carried out with the aid of microwave elements and without the use of expensive digital signal processors. Definitions of the phase and phase difference of the so-called simple signals and noise signals were described. A proposal of a passive radar equipped with several independent quadrature microwave phase discriminators was presented. Ideas of algorithms of object detection and of the distance-to-object estimation designed for this radar have been also sketched.
    Źródło:
    Metrology and Measurement Systems; 2012, 19, 1; 95-104
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wideband Nine-Port Reflectometer
    Autorzy:
    Odrobina, S.
    Staszek, K.
    Wincza, K.
    Gruszczynski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/227101.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    multiport measurement technique
    reflectometer
    reflection coefficient
    measurement uncertainty
    directional coupler
    power divider
    phase shifter
    Opis:
    The paper presents a wideband nine-port reflectometer realized as a cascade connection of six- and five-port reflectometers. It is shown that such a solution allows for a convenient adjustment of circuits’ parameters in order to provide significantly reduced measurement uncertainty with respect to other reported reflectometers. Simultaneously, the proposed network features a simple and flexible design. For the experimental verification, the proposed nine-port reflectometer has been manufactured and incorporated into the system intended for reflection coefficient measurements within the frequency range 2.5 - 3.5 GHz. The obtained results are in an excellent agreement with the values measured using a commercial VNA.
    Źródło:
    International Journal of Electronics and Telecommunications; 2018, 64, 1; 19-25
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wind tunnel flux comparisons using a phase Doppler interferometer
    Autorzy:
    Roten, R.L.
    Post, S.L.
    Werner, A.
    Safa, M.
    Hewitt, A.J.
    Powiązania:
    https://bibliotekanauki.pl/articles/65512.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    wind tunnel
    flux measurement
    Doppler interferometer
    phase Doppler system
    droplet
    Opis:
    It is essential to know the movement of droplets in time and space (i.e. flux) when measuring and/or predicting spray drift in agricultural application. A study was performed to assess the flux measurements of a phase Doppler system against a standard monofilament system in a wind tunnel. The primary objectives of the study were to compare flux from a new phase Doppler system against 1.7 mm cotton and 2.0 mm nylon strings at varying wind speeds (1.4, 4.2, 8.3, 12.5, and 16.7 m ⋅ s–1) and spray exposures times (5, 10, 15, 30, and 60 s) with an overarching hypothesis that the active, phase Doppler is able to accurately measure the flux regardless of exposure and spray mass whereas the static string samplers are limited to a maximum retention. The phase Doppler did measure linearly as expected, however strings did not reach a point in which they loss mass; conversely, they appeared to overload with saturation. These findings are believed to be among many variables which influence the variability of previous mass balance studies.
    Źródło:
    Journal of Plant Protection Research; 2017, 57, 3
    1427-4345
    Pojawia się w:
    Journal of Plant Protection Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel ultrasonic distance measuring system based on correlation method
    Autorzy:
    Gądek, K.
    Jaraczewski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/141521.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ultrasonic measurements
    non-destructive testing
    delay measurement algorithm
    phase correlation
    Opis:
    This paper presents an innovative method for measuring the time delay of ultrasonic waves. Pulse methods used in the previous studies was characterized by latency. The method of phase correlation, presented in this article is free from this disadvantages. Due to the phase encoding with the use of Walsh functions the presented method allows to obtain better precision than previous methods. The algorithm to measure delay of the reflected wave with the use of microprocessor ARM Cortex M4 linked to a PC has been worked out and tested. This method uses the signal from the ultrasonic probe to precisely determine the time delay, caused by the propagation in medium, possible. In order to verify the effectiveness of the method a part of the measuring system was implemented in LabVIEW. The presented method proved to be effective, as it is shown in presented simulation results.
    Źródło:
    Archives of Electrical Engineering; 2014, 63, 3; 385-392
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of Uncertainty of Phase Difference Determination in Presence of Bias
    Autorzy:
    Saranovac, L. V.
    Vučijak, N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/221324.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sinusoidal electrical signals
    phase difference
    bias
    uncertainty of measurement
    MSAL algorithm
    Opis:
    Determination of the phase difference between two sinusoidal signals with noise components using samples of these signals is of interest in many measurement systems. The samples of signals are processed by one of many algorithms, such as 7PSF, UQDE and MSAL, to determine the phase difference. The phase difference result must be accompanied with estimation of the measurement uncertainty. The following issues are covered in this paper: the MSAL algorithm background, the ways of treating the bias influence on the phase difference result, comparison of results obtained by applying MSAL and the other mentioned algorithms to the same real signal samples, and evaluation of the uncertainty of the phase difference.
    Źródło:
    Metrology and Measurement Systems; 2016, 23, 4; 603-614
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Automatic Test Bench for Selected Transmission Parameters of Power Line Conductors
    Autorzy:
    Chruszczyk, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/227032.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    LabVIEW
    power line measurements
    power line communication
    amplitude spectrum
    phase spectrum
    crosstalk measurement
    Opis:
    This paper presents automatic test bench used for measurement of selected high frequency parameters of a power copper line. The aim is fast estimation of line behavior in context of Power Line Communication (PLC). The hardware interface uses sinusoidal waveform generator, digital oscilloscope and a PC-class computer. The software interface created in LabVIEW environment performs signal processing and data presentation.
    Źródło:
    International Journal of Electronics and Telecommunications; 2015, 61, 1; 59-65
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monitoring of phase jitter in fibre optic time and frequency transfer systems
    Autorzy:
    Salwik, K.
    Śliwczyński, Ł.
    Krehlik, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/221405.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    jitter measurement
    phase comparison
    fibre optics
    time and frequency transfer
    bidirectional
    optical amplifier
    Opis:
    The phase jitter enables to assess quality of signals transmitted in a bi-directional, long-distance fibre optic link dedicated for dissemination of the time and frequency signals. In the paper, we are considering measurements of jitter using a phase detector the detected frequency signal and the reference signal are supplied to. To cover the wideband jitter spectrum the detected signal frequency is divided and - because of the aliasing process - higher spectral components are shifted down. We are also examining the influence of a residual jitter that occurs in the reference signal generated by filtering the jitter occurring in the same signal, whose phase fluctuations we intend to measure. Then, we are discussing the evaluation results, which were obtained by using the target fibre optic time and frequency transfer system.
    Źródło:
    Metrology and Measurement Systems; 2018, 25, 3; 487-497
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characteristic pulse detection method for fuzzy area
    Autorzy:
    Geng, Xin
    Du, Baoqiang
    Powiązania:
    https://bibliotekanauki.pl/articles/2173662.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    frequency measurement
    group period
    phase coincidence fuzzy area
    measurement gate
    pomiar częstotliwości
    okres grupowy
    obszar rozmyty koincydencji faz
    bramka pomiarowa
    Opis:
    In order to achieve higher frequency measurement accuracy, this paper proposed a characteristic pulse detection method of fuzzy area based on the quantized phase processing method of different frequency groups. First, the fuzzy area of the group phase coincidence points continuously moved on the time axis after passing through delay elements. The moving distance, that is, the number of the delay elements was determined by the main clock cycle of the D flip-flop. After that, three groups of phase coincidence detection fuzzy areas in different positions were sent to the digital logic module to extract the edge pulses of the phase coincidence detection fuzzy area. The pulse width is determined by the difference between the clock cycles of the delay elements. The clock cycles of different delay units were adjusted to obtain nanosecond or even picosecond circuit detection resolution. Finally, the pulses generated at the edge of the phase coincidence fuzzy area are taken as the switching signal of the frequency signal counter, so the stability of the gate signal and the accuracy of the gate time measurement are improved. The experimental results show that frequency stability can reach the order of E–13/s. In addition, compared with the traditional measurement method, it is characterized by simple structure, low cost, low noises, and high measurement resolution.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 2; art. no. e140553
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The analysis of stress states in steel rods surfaced by welding
    Analiza stanów naprężenia napawanych prętów stalowych
    Autorzy:
    Winczek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/354539.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    phase transformation
    residual welding stresses
    stress measurement
    surfacing
    przemiany fazowe
    naprężenia spawalnicze
    pomiar naprężeń
    napawanie
    Opis:
    In work is presented a method of calculating elasto-plastic states in thermally loaded rods, which takes into account phase transformations that occur during surfacing by welding. Kinetics of phase transformations during heating and cooling is limited by temperature values at the beginning and at the end of austenitic transformation, while the progress of phase transformations during cooling is determined on the basis of TTT-welding diagram, basing on Johnson-Mehl-Avrami-Kolomogorov law for diffusional transformations and Koistinen-Marburger for martensitic transformation. Stress state of a bar subjected to thermo-mechanical loads is described assuming the planar cross section hypothesis and using integral equations of stress equilibrium of a bar as well as simple Hook’s law. Dependence of stresses from strains is assumed on the basis of tensile curves of particular structures, taking into account the influence of temperature. Computations of strains and stresses are investigated in a rod made of S235 steel, loaded by thermal fields generated by a point welding heat source of different intensities. The analysis of origination and development of plastic strains is carried out. In order to verify correctness of the model, experimental tests are carried out on a rod made of S235 steel surfaced with GMA method with geometry and welding parameters assumed in numerical simulations. Residual stresses, calculated taking into account phase transformations and for homogenous material model, are compared with experimental results.
    W pracy przedstawiono sposób obliczeń stanów sprężysto - plastycznych w prętach obciążonych cieplnie, z uwzględnieniem przemian fazowych zachodzących podczas napawania. Kinetykę przemian fazowych podczas nagizewania i chłodzenia limitują wartości temperatur początku i końca austenityzacji. natomiast postęp przemian podczas chłodzenia jest określony w oparciu o spawalniczy wykres ciągłego chłodzenia stali (CTPc-S). bazując na prawach Johnsona-Mehla-Avramiego-Kołomogorova (JMAK) w odniesieniu do przemian dyfuzyjnych i Koistinena-Marburgera dla martenzytycznej. Stan naprężenia pręta poddanego działaniu obciążeń cieplno-mechanicznych opisano przyjmując hipotezę płaskich przekrojów oraz korzystając z całkowych równań równowagi pręta Zależności naprężeń od odkształceń przyjęto na podstawie krzywych rozciągania poszczególnych struktur z uwzględnieniem wpływu temperatury. Wykonano obliczenia pola temperatury, przemian fazowych, odkształceń i naprężeń płaskownika wykonanego ze stali S235, obciążonego punktowym spawalniczym źródłem ciepła o różnej intensywności. Przeprowadzono analizę powstawania i rozwoju odkształceń plastycznych. W oelu weryfikacji poprawności modelu przeprowadzono badania doświadczalne płaskownika wykonanego ze stali S235 napawanego metodą GMA. o geometrii i parametrach napawania przyjętych w symulacjach numerycznych. Porównano naprężenia własne obliczone z uwzględnieniem przemian fazowych oraz dla modelu materiału jednorodnego z wynikami badań doświadczalnych.
    Źródło:
    Archives of Metallurgy and Materials; 2013, 58, 4; 1243-1252
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A High-Speed Fully Digital Phase-Synchronizer Implemented in a Field Programmable Gate Array Device
    Autorzy:
    Frankowski, R.
    Chaberski, D.
    Kowalski, M.
    Zieliński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/221125.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    phase synchronizer
    delay line
    coincidence counting
    quantum information
    time interval measurement
    time-to-digital converters
    field programmable gate array (FPGA)
    Opis:
    Most systems used in quantum physics experiments require the efficient and simultaneous recording different multi-photon coincidence detection events. In such experiments, the single-photon gated counting systems can be applicable. The main sources of errors in these systems are both instability of the clock source and their imperfect synchronization with the excitation source. Below, we propose a solution for improvement of the metrological parameters of such measuring systems. Thus, we designed a novel integrated circuit dedicated to registration of signals from a photon number resolving detectors including a phase synchronizer module. This paper presents the architecture of a high-resolution (~60 ps) digital phase synchronizer module cooperating with a multi-channel coincidence counter. The main characteristic feature of the presented system is its ability to fast synchronization (requiring only one clock period) with the measuring process. Therefore, it is designed to work with various excitation sources of a very wide frequency range. Implementation of the phase synchronizer module in an FPGA device enabled to reduce the synchronization error value from 2.857 ns to 214.8 ps.
    Źródło:
    Metrology and Measurement Systems; 2017, 24, 3; 537-550
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of thermomechanical properties of ferromagnetic NiFega shape memory alloy subjected to pseudoelastic compression test
    Badanie właściwości termomechanicznych ferromagnetycznego stopu z pamięcią kształtu NiFeGa w procesie pseudosprężystego ściskania
    Autorzy:
    Pieczyska, E.
    Dutkiewicz, J.
    Masdeu, F.
    Luckner, J.
    Maciak, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/351312.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    zlokalizowane przemiany fazowe
    test kompresji
    pomiar temperatury
    kamera termowizyjna
    magnetically controlled shape memory alloys
    localized phase transformation
    stress-induced transformation
    compression test
    temperature measurement
    infrared camera
    Opis:
    In the study stress-induced reversible phase transformation in NiFeGa magnetically controlled shape memory alloy subjected to pseudoelastic compression test was investigated. The specimen's mechanical characteristics and temperature changes related to the exothermic martensite transformation and endothermic reverse transformation were measured in contact-less way by using a fast and sensitive infrared camera (IR). It was found that the stress-induced phase transformation process occurs in this alloy in heterogeneous way, since the observed specimen's temperature distribution was not uniform. Stress-strain curves obtained for the first, as well as for the subsequent six loading-unloading compression cycles and their related temperature changes, elaborated as average from the specimen's surface, were analyzed. It was concluded that the stress and the temperature changes developing in the subsequent cycles depend on the applied test conditions, however the highest discrepancies were observed between the first and the second cycles of the compression loading.
    W pracy przedstawiono wyniki badań zmian parametrów mechanicznych oraz temperatury stopu Ni54Fe19Ga27, wykazującego magnetyczną pamięć kształtu. Próbki stopu poddawano procesowi pseudosprężystego ściskania. Temperaturę mierzono za pomocą szybkiej kamery termowizyjnej. Stwierdzono, że indukowana naprężeniem przemiana fazowa zachodzi w tym stopie w sposób niejednorodny, a przebieg charakterystyk mechanicznych i zmian temperatury w kolejnych cyklach obciążania i odciążania prówbki zależy od zastosowanej metodyki badawczej.
    Źródło:
    Archives of Metallurgy and Materials; 2011, 56, 2; 401-408
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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