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Wyświetlanie 1-15 z 188
Tytuł:
Analysis of forced spatial vibrations of a centrifugal pump impeller with axial forces balancing device
Autorzy:
Zhulyov, A.
Martsinkovsky, V.
Kundera, C.
Powiązania:
https://bibliotekanauki.pl/articles/265211.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
wibracje
promieniowanie
wirnik
pompa
vibrations–radial
angular
axial
rotor
impeller
partial systems
self-centering
shaftless pump
Opis:
In this paper, a model of a pump impeller with annular seals and a balancing device, used as a combined support-seal assembly, is considered. The forced coupled radial, angular and axial vibrations of the rotor are determined with consideration of linearized inertial, damping, gyroscopic, positional and circulating forces and moments acting on the impeller from the side of the fluid flow in annular seals. The theoretical analysis is supplemented with a numerical example, the amplitude frequency characteristics are shown.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 3; 737-750
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image encryption combining discrete fractional angular transform with Arnold transform in image bit planes
Autorzy:
Zhou, Z.
Yu, J.
Liao, Q.
Gong, L.
Powiązania:
https://bibliotekanauki.pl/articles/173704.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Arnold transform
bit plane
discrete fractional angular transform
image encryption algorithm
Opis:
A new image encryption algorithm by using a discrete fractional angular transform and Arnold transform in image bit planes is investigated. In the image encryption algorithm, the original image is encrypted by the Arnold transform in image bit planes firstly, and then the resulting image is encrypted by the discrete fractional angular transform further. The key of the image encryption algorithm includes the parameters of the Arnold transform and the order of the discrete fractional angular transform. It is shown that the proposed image encryption algorithm is of high security and strong enough to counteract some conventional image attack manners.
Źródło:
Optica Applicata; 2018, 48, 2; 225-236
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quaternion-based filtering for gyroless attitude estimation without an attitude dynamics model
Autorzy:
Zhang, S.
Xing, F.
Sun, T.
You, Z.
Powiązania:
https://bibliotekanauki.pl/articles/220655.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
quaternion-based filtering
gyroless attitude estimation
angular velocity determination
Kalman filter
Opis:
Conventionally, the filtering technique for attitude estimation is performed using gyros or attitude dynamics models. In order to extend the application range of an attitude filter, this paper proposes a quaternion-based filtering framework for gyroless attitude estimation without an attitude dynamics model. The attitude estimation system is established based on a quaternion kinematic equation and vector observation models. The angular velocity in the system is determined through observation vectors from attitude sensors and the statistical properties of the angular velocity error are analysed. A Kalman filter is applied to estimate the attitude error such that the effect from the angular velocity error is compensated with its statistical properties at each sampling moment. A numerical simulation example is presented to illustrate the performance of the proposed algorithm.
Źródło:
Metrology and Measurement Systems; 2018, 25, 3; 631-643
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical torques and forces in birefringent microplate
Autorzy:
Zenkova, C. Y.
Ivanskyi, D. I.
Kiyashchuk, T. V.
Powiązania:
https://bibliotekanauki.pl/articles/174384.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
evanescent wave
spin angular momentum
birefringent microplate
Opis:
The paper presents a theoretical model for calculating the optical forces caused by the density of spin and orbital momentum and optical torque, caused by the angular momentum typical for a circularly polarized beam or a circular component of an elliptically polarized beam. Total internal reflection at the plate–air interface implemented by the birefringent plate spattered with nanoparticles of gold creates the conditions for the allocation of the predominant action of the vertical spin of the evanescent wave, which has recently been predicted theoretically.
Źródło:
Optica Applicata; 2017, 47, 3; 483-493
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stanowisko badawcze napędów elektrohydraulicznych
The laboratory research stand of electrohydraulic drives
Autorzy:
Zawarczyński, Ł.
Stefański, T.
Powiązania:
https://bibliotekanauki.pl/articles/270576.pdf
Data publikacji:
2013
Wydawca:
Centralny Ośrodek Badawczo-Rozwojowy Aparatury Badawczej i Dydaktycznej, COBRABiD
Tematy:
silniki elektryczne
napęd elektryczny
napęd hydrauliczny
regulacja prędkości obrotowej
electric motor
electric drive system
hydraulic drive system
angular velocity control system
Opis:
Przedstawiono stanowisko laboratoryjne do badań napędów elektrycznych i hydraulicznych. Do napędu pomp o stałej objętości geometrycznej zastosowano podstawowe rodzaje silników, tj. indukcyjny oraz ze wzbudzeniem od magnesów trwałych (synchroniczny i bezszczotkowy prądu stałego), które zasilano z falownika napięcia. Stanowisko wyposażono w typowe hydrauliczne zawory proporcjonalne, w tym: regulacyjny, dławiący, przelewowy oraz rozdzielacz, które umożliwiają uzyskanie różnej konfiguracji funkcjonalnej stanowiska. Do pomiaru wielkości elektrycznych, mechanicznych i hydraulicznych zastosowano specjalizowane, mikroprocesorowe układy pomiarowe. Zaprezentowano możliwości badawcze stanowiska oraz wybrane wyniki badań eksperymentalnych.
The laboratory research stand of electric and hydraulic drives was presented. The basic constructions of inverter-fed drives, asynchronous (80 Hz) and synchronous with the excitation from permanent magnet BLDC and PMSM with power equal to 2,5 kW were used. Electric drives were applied to drive hydraulic pumps (gear and piston). The hydraulic part is controlled by proportional valves: flow control, directional control and direct operated control valve. Specialised measuring system to control and diagnose electric drives, pumps, and another hydraulic elements was applied. The research capabilities of the stand and the example results of experimental tests for the chosen control methods were presented.
Źródło:
Aparatura Badawcza i Dydaktyczna; 2013, 18, 1; 61-67
2392-1765
Pojawia się w:
Aparatura Badawcza i Dydaktyczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza dynamiki wentylatora promieniowego w warunkach niewspółosiowości wałów wirnika i silnika
Analysis of centrifugal fan's dynamics in conditions of rotor and motor shafts' misalignment
Autorzy:
Zachwieja, J.
Powiązania:
https://bibliotekanauki.pl/articles/329000.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
niewspółosiowość równoległa
niewspółosiowość kątowa
oś
holospectrum
ekscentryczność orbity
parallel misalignment
angular misalignment
orbit excentricyty
Opis:
Istotnym problemem jaki występuje w diagnozowaniu maszyn wirnikowych jest poprawna identyfikacja symptomów ich uszkodzeń. W przypadku grupy maszyn przepływowych, do której należą przemysłowe wentylatory promieniowe, najczęściej występującymi uszkodzeniami są: niewyważenie wirnika, defekty łożysk oraz niewspółosiowość wałów. Tryb pracy ciągłej urządzeń powoduje, że często niemożliwe jest wyłączenie maszyny i bezpośredni pomiar wartości równoległego przesunięcia i względnego kąta obrotu osi wałów. Dlatego rzeczą istotną staje się poszukiwanie symptomów tego typu uszkodzenia metodami pośrednimi, dającymi duży stopień pewności w przewidywaniu wpływu niewspółosiowości wałów na dynamikę pracy wentylatora. Zagadnienia te zostały omówione w artykule.
An important problem connected with turbomachine diagnostics is identifying its failure symptoms. In case of the fluid-flow machines, which include industrial centrifugal fans, the most common failures are: a rotor's unbalance, bearings defect and a shaft misalignment. Continuous operation mode results in a fact that it is often impossible to disengage the machine and take a direct measurement of the translation and shaft axes' angle of relative revolution. Therefore an important thing is to determine the symptoms of a failure using indirect methods and a possibility to predict the influence of shafts misalignment on fan operation dynamics. These problems were discussed in this article.
Źródło:
Diagnostyka; 2010, 1(53); 61-70
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Image encryption algorithm by using the logistic map and discrete fractional angular transform
Autorzy:
Yu, J.
Li, Y.
Xie, X.
Zhou, N.
Zhou, Z.
Powiązania:
https://bibliotekanauki.pl/articles/173813.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
image encryption
logistic map
discrete fractional angular transform
Opis:
A new image encryption scheme based on logistic map and discrete fractional angular transform has been proposed. In the proposed scheme, the original image is encrypted with the random sequence generated by the logistic map, and the encrypted image is subsequently processed by the discrete fractional angular transform, which produces the ciphertext after double encryptions. The parameters of the logistic map and the order of the discrete fractional angular transform serve as the main keys of the image encryption algorithm. Simulation results show that the proposed image encryption algorithm can effectively resist the attacks of statistical analysis, and has acceptable encryption effect and security.
Źródło:
Optica Applicata; 2017, 47, 1; 141-155
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Static Unbalance Analysis and Its Measurement System For Gimbals Axes of an Inertial Stabilization Platform
Autorzy:
Yang, H.
Zhao, Y.
Li, M.
Wu, F.
Powiązania:
https://bibliotekanauki.pl/articles/221513.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inertial stabilization platform
mass eccentricity
angular position turntable
dynamical model
least-square fitting
Opis:
To reduce the influence of the static unbalance on an infrared missile guidance system, a new static unbalance measure system for the gimbals axes has been developed. Considering the coupling effects caused by a mass eccentricity, the static balance condition and measure sequence for each gimbal axis are obtained. A novel static unbalance test approach is proposed after analyzing the dynamic model of the measured gimbal axis. This approach is to drive the measured gimbal axis to do sinusoidal reciprocating motion in a small angle and collect its drive currents in real time. Then the static unbalance of the measured gimbal axis can be obtained by the current multi-cycle integration. Also a measuring system using the proposed approach has been developed. A balanced simulator is used to verify the proposed approach by the load and repeatability tests. The results show the proposed approach enhances the efficiency of the static unbalance measurement, and the developed measuring system is able to achieve a high precision with a greater stability.
Źródło:
Metrology and Measurement Systems; 2015, 22, 1; 51-68
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial light modulator design and generation of structured electromagnetic waves using digital light processors
Autorzy:
Yalcinkaya, F.
Koc, T.
Pala, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2172826.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
spatial light modulator
digital micro-mirror device
digital light processing
structured electromagnetic wave
orbital angular momentum
hologram
Opis:
Spatial light modulators (SLMs) are versatile devices used for optical studies. These instruments have a wide area of application in photonics. Additionally, SLMs have potential utility in different applications, such as biomedical applications, laser based surgery for precise cutting and as optical tweezers to separate cells in a petri container. However, the high cost of SLM devices prevents their widespread use in many areas, including industrial areas and scientific research laboratories. This paper demonstrates how to design a digital light processor (DLP) based low-cost SLM and describes how to obtain structured electromagnetic waves with the designed SLM. Therefore, this research was undertaken to design and produce a low-cost SLM device for optical applications. For this purpose, two prerequisites had to be fulfilled, the first was to use suitable components of a projection device with DLP-based digital micro-mirror device (DMD), and the second was to eliminate unnecessary SLM components from the system. Finally, holographic images reflected on the SLM screen were created by using Mathematica software program to change the amplitude and phase of the electromagnetic waves in order to obtain the structured electromagnetic waves.
Źródło:
Optica Applicata; 2022, 52, 3; 461--479
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Earth Rotation Parameters Prediction and Climate Change Indicators in It
Autorzy:
Xu, Xueqing
Zhou, Yonghong
Xu, Cancan
Powiązania:
https://bibliotekanauki.pl/articles/2174950.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Centrum Badań Kosmicznych PAN
Tematy:
EOP prediction
effective angular momentum
interannual ΔLOD
climate change indicators
Opis:
As one of the participants in the Second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC), we submitted two data files. One is 365 days’ predictions into the future for Earth orientation parameters (EOP) (the position parameters Px and Py, the time parameters UT1-UTC and length of day changes ΔLOD), processed by the traditional least-square and autoregressive (LS + AR) model. Another is 90 days’ predictions by the combined least-square and convolution method (LS + Convolution), with effective angular momentum (EAM) from Earth System Modelling GeoForschungsZentrum in Potsdam (ESMGFZ). Results showed that the LS + Convolution method performed better than the LS + AR model in short-term EOP predictions within 10 days, while the traditional LS + AR model presented higher accuracy in medium-term predictions over 10-90 days. Furthermore, based on the climate change information in Earth’s rotation (mainly in the interannual variations of LOD), the climate change indicators are investigated with ΔLOD observations and long-term predictions. After two intermediate La Nina events were detected in the climate-related ΔLOD observations during the period of 2020-2022, another stronger La Nina phenomenon is indicated in the climate-related ΔLOD long-term predictions.
Źródło:
Artificial Satellites. Journal of Planetary Geodesy; 2022, 57, Special Issue 1; 262--273
2083-6104
Pojawia się w:
Artificial Satellites. Journal of Planetary Geodesy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Prediction of Polar Motions by Piecewise Parameterization
Autorzy:
Wu, Yuanwei
Zhao, Xin
Yang, Xinyu
Powiązania:
https://bibliotekanauki.pl/articles/2174948.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Centrum Badań Kosmicznych PAN
Tematy:
earth rotation prediction
effective angular momentum functions
AAM
OAM
Opis:
Natioinal Time Service Center of Chinese Academy of Sciences, Lintong, Shaanxi, China e-mail: yuanwei.wu@ntsc.ac.cn ABSTRACT. On seanonal timescale, the variation of Earth rotation is mainly regulated by angular momentum exchanges between the solid Earth and the fluidal atmosphere, ocean and hydrosphere. In the 2nd EOP PCC, we developed Dill2019’s method for polar motion prediction, using piecewise autoagressive parameters. The maximum prediction errors within 90 days are 36 and 16 mas for polar motion x and y components, respectively. Compared with Bulletin A, the mean absolute error of polar motion y prediction is improved by 20% in all timescale, and with a maximum improvement of 49% on the 5th day. Whereas, for polar motion x, the performance is slightly better (2% - 8%) within 30 days but worse (−7%∼ −19%) within 30∼90 days. We found that the prediction accuracy is very sensitive to the quality of the angular momentum data. For example, on average, the prediction of polar motion y is around 2 times better than polar motion x. In addition, we found the accuracy of 30-90 days prediction is dramatically decreased in the year 2020. We suspect that such deterioration might be due to the pandemic of coronavirus COVID-19, which suppressed global airline activities by more than 60%, then result in a lose of air-borne meteorological data, which are important for weather forecast.
Źródło:
Artificial Satellites. Journal of Planetary Geodesy; 2022, 57, Special Issue 1; 290--299
2083-6104
Pojawia się w:
Artificial Satellites. Journal of Planetary Geodesy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light field camera all-in-focus image acquisition based on angular information
Autorzy:
Wu, Yingchun
Cheng, Xing
Liang, Jie
Wang, Anhong
Zhao, Xianling
Powiązania:
https://bibliotekanauki.pl/articles/1835771.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
all-in-focus image fusion
light field camera
spatial information
angular information
macro-pixel energy difference
Opis:
Traditional light field all-in-focus image fusion algorithms are based on the digital refocusing technique. Multi-focused images converted from one single light field image are used to calculate the all-in-focus image and the light field spatial information is used to accomplish the sharpness evaluation. Analyzing the 4D light field from another perspective, an all-in-focus image fusion algorithm based on angular information is presented in this paper. In the proposed method, the 4D light field data are fused directly and a macro-pixel energy difference function based on angular information is established to accomplish the sharpness evaluation. Then the fused 4D data is guided by the dimension increased central sub-aperture image to obtain the refined 4D data. Finally, the all-in-focus image is calculated by integrating the refined 4D light field data. Experimental results show that the fused images calculated by the proposed method have higher visual quality. Quantitative evaluation results also demonstrate the performance of the proposed algorithm. With the light field angular information, the image feature-based index and human perception inspired index of the fused image are improved.
Źródło:
Optica Applicata; 2021, 51, 2; 289-304
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Presentation of the Selected Statistical Notions Based on Tukeys Concept of Observation Depth in the Sample
Wybrane pojęcia statystyczne w świetle koncepcji zanurzenia punktu w próbie - ujęcie numeryczne
Autorzy:
Wagner, Wiesław
Kobylińska, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/905269.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
depth measure
contour of depth
simplicial depth
the cosine method
the convex combination method
the tree triangle area method
the angular transformation method
Opis:
The study provides presentation of selected statistical concepts based on data depth by Tukey. The concepts as: the rang of depth, the half-space convex, contour, simplicial depth breakdown points, position numerical measures, the trimmed mean depth, regression depth and the set of generally positive points were exemplified in a two-dimensional space of the dataset. There are also given numerical algorithms in some cases to indicate already mentioned concepts and to study their affined transformation. There are also given example for a one-dimensional space besides general description
W pracy omówiono definicję zanurzenia punktu w próbie oraz wywodzące się z lej koncepcji pewne inne pojęcie statystyczne. Przedstawiono między innymi wskaźniki określające stopień zanurzenia oraz zaproponowano metody numerycznego ich wyznaczania.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 2003, 164
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Maximum Torque Control of 3-phase induction motor drives
Autorzy:
Wach, P.
Powiązania:
https://bibliotekanauki.pl/articles/141618.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
induction motor control
angular velocity control
direct torque control
field oriented control
DC-AC power converters
Maximum Torque Control
Opis:
Maximum Torque Control (MTC) is a new method applied for control of induction motor drives. The drive is controlled by dc voltage supplying a converter in the range below nominal speed and by a field that weakens for a speed range above the nominal speed. As a consequence, the control is quite similar to the control of a classical separately excited dc motor. This control method could be explained as a kind of simplification of Direct Torque Control (DTC), because the switching scheme is the same as for the DTC, but the variable responsible for a torque control is constantly set for “torque increase”. This kind of control of induction motor drive is simpler than DTC because torque values need not be estimated. The proposed control method offers very good performance for 3-phase induction motors and requires smaller switching frequency in comparison to DTC and Field Oriented Control (FOC). The application of the control is widely demonstrated for a 3-phase 315 kW, 6 kV motor drive by use of computer simulation.
Źródło:
Archives of Electrical Engineering; 2018, 67, 2; 433--445
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Researches of pneumatic sowing machine with peripheral cells location and inertial superfluous seeds extraction
Autorzy:
Vasylkovska, K.
Vasylkovskyy, O.
Anisimov, O.
Trykina, N.
Powiązania:
https://bibliotekanauki.pl/articles/410833.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
pneumatic seeding machine/device
seed disc
experiment
cells filling factor
dilution
cells angular speed
Opis:
In the article we provide the new design of pneumatic sowing machine with peripheral cells on the seed disk and a passive device for removing extra seeds with inertia method for precise seeding of cultivated crops. A series of studies was proposed for sugar beet seeds sowing device, we defined the influence of dilution in a vacuum chamber of sowing device and angular velocity cell seed disk on the cells filling factor. The design of the new pneumatic sowing machine can significantly reduce the vacuum in the system having increased the angular speed in cell seed disk to the values of seeding device travelling speed, thus provide a constant point of seeds drop from the seed disc at the same trajectory of their flight to the furrows and the qualitative cells filling. To determine the rational parameters and modes of sowing device we used method of multifactor experiment planning. We determined the main levels and intervals of varying factors for sugar beet sowing along with determining the filling factor of cell seed disk. With application of package Statistica 6.0. for parameter optimization - cell seed disk filling factor was constructed response surface and line of even output.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2015, 4, 4; 85-89
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
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