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Wyświetlanie 1-15 z 74
Tytuł:
Modeling and analysis of 12-pulse inverter in shipboard or aircraft
Autorzy:
Che, Y.
Zhou, J.
Liu, G.
Xu, J.
Zhao, Y.
Powiązania:
https://bibliotekanauki.pl/articles/260236.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
generalized state space averaging (GSSA)
state space averaging (SSA)
MATLAB
Opis:
With the development of DC distribution system within the isolated power system of a ship or an aircraft, more constant frequency loads will be supplied by inverters connected to DC main bus. In the operating mode conversion process of an isolated power system, inverters will inevitably suffer from serious disturbance and affect the stability of the system. Therefore, it is important to establish a model of the inverter that reflects its dynamic characteristics and based on which to conduct the stability analysis. This paper proposes a 12-pulse inverter model based on the generalized state space averaging (GSSA) method. This model can overcome the limitations of 12-pulse inverter state space averaging (SSA) model in transient analysis with good accuracy and fast analysis ability effectively. Three kinds of models for a 12-pulse aircraft inverter are built in MATLAB, namely GSSA model, SSA model and detail device model. The simulation results show the high accuracy of GSSA model in stability analysis. This study provides an effective analytical tool for stability analysis of 12-pulse inverter and also provides a reference for inverter modeling research of isolated power system such as in aircraft or ship.
Źródło:
Polish Maritime Research; 2017, S 3; 136-142
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of typical flow disturbing elements on the flow rate in selected averaging Pitot tubes
Autorzy:
Pochwała, S.
Kabaciński, M.
Pospolita, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933974.pdf
Data publikacji:
2012
Wydawca:
Politechnika Gdańska
Tematy:
averaging pitot tubes
flowmeter
Opis:
Flowmeters with averaging Pitot tubes are becoming more and more common in the industrial practice. It is often the case in long straight sections of channels with large diameters that the conditions regarding the adequately long sections of pipelines before and behind a flowmeter cannot be fulfilled. This is associated with the occurrence of an additional measurement uncertainty with an unknown value. Most of the information regarding this issue can be found for the case of Venturi probes. The amount of data regarding the flow averaging Pitot tubes is also limited. Hence, the decision to undertake the proposed subject. The conducted research made it possible to state recommendations regarding the metrology of testing. The results indicate that it is not only the distance from the flow disturbing element that plays a role but it is also the plane in which the sensor is located that affects the uncertainty of measurements of the flow averaging Pitot tubes.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2012, 16, 3-4; 219-228
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some averaging results for ordinary differential inclusions
Autorzy:
Bourada, Amel
Guen, Rahma
Lakrib, Mustapha
Yadi, Karim
Powiązania:
https://bibliotekanauki.pl/articles/729511.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
ordinary differential inclusions
averaging method
Opis:
We consider ordinary differential inclusions and we state and discuss some averaging results for these inclusions. Our results are proved under weaker conditions than the results in the literature.
Źródło:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization; 2015, 35, 1; 47-63
1509-9407
Pojawia się w:
Discussiones Mathematicae, Differential Inclusions, Control and Optimization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A contribution to modelling of composite solids
Modelowanie kompozytów a trójosiową symetrią
Autorzy:
Nagórko, W.
Wągrowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/281410.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
modelling
elastic composites
tolerance averaging
Opis:
The aim of this paper is to prove that micro-periodic composites made of linear-elastic isotropic components and having a hexagonal representative cell with the triple axis of material symmetry are also isotropic in the macro-scale. The prove of this statement will be given on the basis of the tolerance averaging method of modelling, Woźniak and Wierzbicki (2000).
W pracy rozważa się kompozyty sprężyste o mikroperiodycznej strukturze, których elementy reprezentatywne mają trójosiową symetrię. Wykazuje się, że takie ciała mają w modelu otrzymanym w wyniku zastosowania techniki uśredniania tolerancyjnego własności ciał izotropowych.
Źródło:
Journal of Theoretical and Applied Mechanics; 2002, 40, 1; 149-158
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Applicability of Flow Averaging Pitot Tubes in the Areas of Flow Disturbance
Autorzy:
Pochwała, S.
Pospolita, J.
Powiązania:
https://bibliotekanauki.pl/articles/221838.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
averaging Pitot tubes
flowmeter
measurement uncertainty
Opis:
The issues connected with the complex design of various facilities, including up-to-date boiler equipment as well as the ways of organizing the space around them, are the reasons why there is often a lack of room for mounting a flowmeter in accordance with the recommendations of manufacturers. In most cases the problem is associated with ensuring sufficient lengths of straight pipe leading into and out of a flowmeter. When this condition cannot be fulfilled, the uncertainty of measurement increases above the value guaranteed by the manufacturer of the flowmeter. This sort of operation problem has encouraged the authors of this paper to undertake research aimed at the analysis of applicability of averaging Pitot tubes in the areas of flow disturbance.
Źródło:
Metrology and Measurement Systems; 2016, 23, 1; 71-84
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using conditional averaging of delayed signals to measure phase shift angle
Autorzy:
Kowalczyk, Adam
Szlachta, Anna
Powiązania:
https://bibliotekanauki.pl/articles/2173906.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conditional averaging
delayed signal
mean value
Opis:
A novel measurement method and a brief discussion of basic characteristics of measuring the phase shift angle between two sinusoidal signals of the same frequency are presented in this paper. It contains a mathematical model for using conditional averaging of a delayed signal interfered with noise to measure the phase shift angle. It also provides characteristics of conditional mean values and discusses the effect of random interferences on the accuracy of the phase shift measurement. The way to determine the variance of the conditional mean value, together with the assessment of standard and expanded uncertainty, are described. The uncertainty characteristic shows the complementary properties of the discussed angle measurement principle for small absolute values || (minimum for = 0) relative to the correlation principle, where the minimum measurement uncertainty is present for = /2
Źródło:
Metrology and Measurement Systems; 2022, 29, 4; 655--667
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of disturbed flow after an elbow on metrological properties of a Flow Averaging Tube
Autorzy:
Kabaciński, M.
Powiązania:
https://bibliotekanauki.pl/articles/114498.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
velocity profile measurement system
averaging Pitot tube
Flow Averaging Tube K-factor
elbow flow
automated test stand
Opis:
Experimental results of air velocity profiles and Flow Averaging Tubes (FAT®) K-factor measured behind an elbow are presented in this paper. The pipeline diameter was D=150 mm, while the range of mean velocities w=9…30 m/s. Velocity profiles were determined both in the vertical and horizontal plane in the respective distances L/D of a pipeline from 3 to 18. In the places of the measured velocity profiles, three cross-sections of flow averaging tubes (circular, streamlined and two-profile) were placed to determine the characteristics of K-factor. Moreover, a fully automated test stand is presented in this paper. The completed experiment allows shortening the distance between an elbow and a flowmeter installation place and informing about the value of a correction factor, which can be used to minimize the measurement uncertainty of the air flow rate. It was stated that the horizontal plane is better to install a probe because of the velocity profile and better results of repeatability.
Źródło:
Measurement Automation Monitoring; 2016, 62, 1; 7-16
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of flowing fluid effect on flow averaging tube
Autorzy:
Kabaciński, M.
Lachowicz, C.
Pospolita, J.
Powiązania:
https://bibliotekanauki.pl/articles/1943247.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska
Tematy:
flow averaging tubes
numerical simulations
flow measurements
Opis:
This paper presents a mathematical model and results of numerical simulations for a fluid flow around a flow averaging tube. The calculations have been performed using the commercially available FLUENT software. The authors have applied the currently known studies of the models of turbulence and their applicability in certain flow conditions and hence selected the RNG k-epsylon turbulence model including appropriate functions to be used for determination of pressures and velocities at the sites of occurrence of considerable gradients. The distributions of pressures and velocities around a sensor are presented along with pressure distributions, instantaneous and averaged in time, on the measuring tube surface. The paper determines the frequencies of measuring tube free vibrations for one sided and two-sided tube fitting for the tube length in the range 100–1500mm. This analysis has been conducted with the aid of solving equations for free undamped vibrations for specific models. The graphical presentation involves an admissible range of tube lengths with one and two-sided fitting for the specified flowing air velocities.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 3-4; 217-226
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new method of frequency offset correction using coherent averaging
Autorzy:
Gajewski, P.
Łopatka, J.
Piotrkowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/308860.pdf
Data publikacji:
2005
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
coherent averaging
jitter
drift
frequency offset correction
Opis:
This paper describes a new method of frequency offset correction to improve clock stability in communication systems where the temporary drift or jitter of phase angle is not accepted. This method bases on coherent spectral averaging with a special phase scanning algorithm. Achieved results show that proposed method is effective for strongly degraded signals. Method is useful for precise phase angle reconstruction in these systems where clock stability of the transceiver and receiver is insufficient.
Źródło:
Journal of Telecommunications and Information Technology; 2005, 1; 142-146
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free vibrations spectrum of periodically inhomogeneous Rayleigh beams using the tolerance averaging technique
Autorzy:
Świątek, Marcin
Domagalski, Łukasz
Jędrysiak, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/949167.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
periodicity cell
Rayleigh beam
tolerance averaging technique
Opis:
In this paper, linear-elastic Rayleigh beams with a periodic structure are considered. Dynamics of such beams is described by partial differential equations with non-continuous highly oscillating coefficients. The analysis of dynamic problems using the aforementioned equations is very often problematic to perform. Thus, other simplified models of Rayleigh beams are proposed. Some of these models are based on the concept of the effective stiffness. Among them, one can distinguish the theory of asymptotic homogenization. However, in these models, the size of the mesostructure parameter (the size of a periodicity cell) is often neglected. Therefore, a non-asymptotic averaged model of the periodic beam is introduced, called the tolerance model, which is derived by applying the tolerance averaging technique (TA). The obtained tolerance model equations have constant coefficients, and in contrast to other averaged models, some of them depend on the size of the periodicity cell.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 1; 141-154
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The possibilities of optokinetic nystagmus cycles averaging
Autorzy:
Pander, T.
Czabański, R.
Przybyła, T.
Pojda-Wilczek, D.
Powiązania:
https://bibliotekanauki.pl/articles/333419.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Tematy:
uśrednianie sygnałów
ENG signal
optokinetic nystagmus
signal averaging
Opis:
The analysis of eyes movements is a crucial part of eyes examination performed by clinicians. One of the characteristic type of eyes movements is a saccade. Its accurate detection is the base for further processing including the estimation of saccade parameters such as velocity, amplitude and duration. This paper presents averaging of optokinetic nystagmus (OKN) cycles that allows comparing and detecting different types of nystagmus phenomena. In order to average the OKN cycles the ENG signal needs to be processed. The saccade detection function is used to find the location of saccades in OKN waveform allowing the ENG signal to be divided into cycles. The resulting cycles are aligned using the Fourier shift method and then averaged providing the OKN cycle model, which can be used for evaluating the eyes at different movement conditions.
Źródło:
Journal of Medical Informatics & Technologies; 2012, 19; 25-31
1642-6037
Pojawia się w:
Journal of Medical Informatics & Technologies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-stationary heat transfer in a hollow cylinder with functionally graded material properties
Niestacjonarny przepływ ciepła w wydrążonym cylindrze wykonanym z materiału o funkcyjnej gradacji własności
Autorzy:
Ostrowski, P.
Michalak, B.
Powiązania:
https://bibliotekanauki.pl/articles/281045.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
heat transfer
functionally graded material
tolerance averaging approach
Opis:
The unidirectional non-stationary heat conduction in a two-phase hollow cylinder is considered. The conductor is made of two-phase stratified composites and has smooth gradation of effective properties in the radial direction. Therefore, we deal here with a special case of functionally graded materials, FGM. The formulation of mathematical model of the conductor is based on a tolerance averaging approach (TAA). Application to the non-stationary heat conduction and a comparison of the tolerance model with the asymptotic one is shown. The effect of geometry and material properties of the conductor on the temperature field is examined.
W pracy rozważano niestacjonarne przewodzenia ciepła w dwuskładnikowym wydrążonym cylindrze. Przewodnik jest wykonany z dwuskładnikowego warstwowego kompozytu mającego łagodną zmienność efektywnych własności w kierunku promieniowym. Stąd mamy tutaj do czynienia ze specjalnym przypadkiem materiału o funkcyjnej gradacji własności (ang. functionally graded materiale, FGM). Zbudowanie uśrednionego modelu matematycznego rozpatrywanego przewodnika jest oparte na technice tolerancyjnej aproksymacji. W pracy pokazano zastosowanie otrzymanego modelu tolerancyjnego i porównanie wyników z wynikami dla modelu asymptotycznego w przypadku niestacjonarnego przewodzenia ciepła. Zbadano wpływ zmienności geometrii i własności materiałowych przewodnika na pole tempertatury.
Źródło:
Journal of Theoretical and Applied Mechanics; 2011, 49, 2; 385-397
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gear fault diagnosis and industrial applications
Autorzy:
Combet, F.
Powiązania:
https://bibliotekanauki.pl/articles/329514.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
gear profile
time synchronous averaging
local tooth faults
Opis:
This paper introduces the concept of a gear profile, which is the polar representation of the time synchronous averaged vibration signal computed on the rotation period of a pinion. A gear profile provides an attractive visual representation of the meshing efforts on the individual teeth for each of the gears present in a gearbox. It is mostly useful for the detection of local tooth faults (cracks, pitting) or shaft eccentricity faults. Its computation however presents some pitfalls as some parameters need to be selected with care: choice of the mesh harmonic to demodulate, filter bandwidth, signal duration for the time averaging. We propose some practical rules on how to select them. The amplitude and frequency modulation functions of the profile can then be computed, and the amount of the modulation may be quantified by some parameters. We also present a case where the electrical currant measurement can be very helpful for gear fault diagnosis. The technique is illustrated on a few industrial cases.
Źródło:
Diagnostyka; 2012, 1(61); 9-12
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Algorithmic method for phase angle shift of noisy voltages using conditional averaging of delayed signals absolute value
Autorzy:
Kowalczyk, A.
Szlachta, A.
Powiązania:
https://bibliotekanauki.pl/articles/221009.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
phase angle shift
additive disturbance
conditional signal averaging
Opis:
The method of a phase shift angle measurement using conditional averaging of delayed signal absolute value (CAAV) is presented in this paper. The input sinusoidal signal x(t) is without noise. White noise with normal distribution and band limited to low frequencies has been applied as disturbance of delayed sinusoidal signal z(t). Noise n(t) - N(0, δn) is added to the delayed signal - the noised and delayed signal z(t) is obtained. The phase angle shift is proportional to time location of CAAV's minimum (minimum of the characteristic of conditional averaging of delayed signal's absolute value). The phase angle shift can be determined on the basis of conditional averaging value of elaborated algorithm. The characteristics of conditional average of delayed signal's absolute value in the surrounding of the minimum of this function (the results of practical investigations and theoretical calculation) are presented. The experimental variance of characteristic CAAV in surroundings of the minimum (obtained from practical investigations and calculation) is illustrated in the paper. The algorithms of conditional averaging have been elaborated and practically realized in the LabVIEW environment.
Źródło:
Metrology and Measurement Systems; 2011, 18, 1; 137-144
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Machine vision based Vernier caliper reading technology research
Autorzy:
Chen, Wen-Meng
Wang, Hong-Xi
Wang, Guan-Wei
Liang, Wen-Hong
Powiązania:
https://bibliotekanauki.pl/articles/2173903.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Vernier calipers
convolutional neural networks
error averaging
alternate projection
Opis:
Accurate and fast access to Vernier caliper readings is a critical issue in automated verification of Vernier calipers. To address this problem, this paper proposes a machine vision-based algorithm for reading the Vernier caliper’s displayed value. The suggested method first employs threshold segmentation and template matching to determine the region of interest and obtain the main ruler digit position by alternate projection. Then, we apply the improved LeNet5 network to identify the main ruler of the Vernier caliper, Moreover, we developed the first and last inscription method for reading the decimal part of the Vernier caliper and established our data set for model training. Extensive experiments on reading the displayed value have demonstrated our algorithm’s accuracy, which achieves a displayed value reading accuracy of 100%. Compared to other methods, the proposed technique affords better stability and accuracy.
Źródło:
Metrology and Measurement Systems; 2022, 29, 4; 779--793
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 74

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