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Wyświetlanie 1-15 z 21
Tytuł:
Magnetic equivalent circuit model for unipolar hybrid excitation synchronous machine
Autorzy:
Kupiec, E.
Przyborowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/141541.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hybrid excitation
magnetic equivalent circuit
synchronous machine
Opis:
Lately, there has been increased interest in hybrid excitation electrical machines. Hybrid excitation is a construction that combines permanent magnet excitation with wound field excitation. Within the general classification, these machines can be classified as modified synchronous machines or inductor machines. These machines may be applied as motors and generators. The complexity of electromagnetic phenomena which occur as a result of coupling of magnetic fluxes of separate excitation systems with perpendicular magnetic axis is a motivation to formulate various mathematical models of these machines. The presented paper discusses the construction of a unipolar hybrid excitation synchronous machine. The magnetic equivalent circuit model including nonlinear magnetization curves is presented. Based on this model, it is possible to determine the multi-parameter relationships between the induced voltage and magnetomotive force in the excitation winding. Particular attention has been paid to the analysis of the impact of additional stator and rotor yokes on above relationship. Induced voltage determines the remaining operating parameters of the machine, both in the motor and generator mode of operation. The analysis of chosen correlations results in an identification of the effective control range of electromotive force of the machine.
Źródło:
Archives of Electrical Engineering; 2015, 64, 1; 107-117
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of feedback controlled fluid-induced instabilities in rotor system supported by hydrodynamic bearings
Autorzy:
Ferfecki, P.
Sikora, R.
Poruba, Z.
Powiązania:
https://bibliotekanauki.pl/articles/229847.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rotor system
hydrodynamic bearing instability
kinematic excitation
Opis:
In certain operating conditions, the oil-film forces, by which the hydrodynamic bearings act on the rotor, destabilize and induce a self-excited vibration. There are many solution based on modifications of the bearing geometry to enlarge the operational range of the hydrodynamic bearing as a tilting pad bearing, lemon bore, etc. or usage of the dampers whose operation is based only on the dissipation of mechanical energy. In this paper several concepts based on controlled kinematic excitation of the bearing shells is investigated by computer simulation and by experimental test. The mathematical model of the uncontrolled and controlled rotor system contains the nonlinear hydrodynamic forces determined by the solution of the Reynolds equation assuming short case of bearing. To solve the equation of motion the Runge-Kutta method of the 4th order with Dormand-Prince modification and variable length of the integration step is used. The computer simulations were performed for rotor system without feedback control and with feedback controller. The main objectives of the numerical analysis were determination of the stability regions of the vibration excited by the imbalance forces. Results of the computer simulations proved that the analyzed approaches reduce amplitude of the rotor vibration caused by the imbalance forces. Experimental test and computer simulations demonstrate that the active vibration control increases considerably the rotation speed when the self-excited vibration of the oil-film occurred.
Źródło:
Archives of Control Sciences; 2010, 20, 3; 287-301
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Study of Forced Vibration Suppression by Parametric Anti-Resonance
Autorzy:
Pešek, L.
Šulc, P.
Půst, L.
Powiązania:
https://bibliotekanauki.pl/articles/176947.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
active damping
parametric anti-resonance
external harmonic excitation
Opis:
The parametric anti-resonance phenomenon as an active damping tool for suppression of externally excited resonant vibration is numerically studied herein. It is well known fact that the anti-resonance phenomenon, i.e. the stiffness periodic variation by subtractive, combination resonance frequency, brings stabilization and cancelling into self-excited vibrations. But this paper aims at a new possibility of its application, namely a damping of externally excited resonant vibration. For estimation of its effect we come both from a characteristic exponent of the analytical solution and numerical solution of forced vibration of 2DOF linear system with additional parametric excitation. The amplitude suppression owing to the parametric anti-resonance is studied on several parameters of the system: a depth of parametric excitation, mass ratio, damping coefficient and small frequency deviations from the parametric anti-resonance.
Źródło:
Archives of Acoustics; 2016, 41, 3; 527-533
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Capability of synchronous machines to ride through events with high ROCOF
Autorzy:
Assenkamp, Alf
Kreischer, Christian
Kulig, Stefan
Powiązania:
https://bibliotekanauki.pl/articles/140451.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ROCOF
under-excitation protection
turbo-generator
low-inertia grids
Opis:
The transition of power grids to implement large amounts of nonsynchronous renewables reduces the inertia in the power system. Therefore, the rate of change of fre- quency (ROCOF) after a fault of given energy is higher in low inertia grids than in grids with mainly synchronous machines operating. Standard faults for the design of existing synchronous machines assume fixed frequency grids, in which an electrically close fault happens. It is not tested, if the machines can ride through transient disturbances with high ROCOF. For ROCOF values of up to 1 Hz/s as foreseen for the upcoming grid code of the Republic of Ireland and up to 2 Hz/s for Northern Ireland, a thorough verification, if generators are capable to ride through such events is necessary. For this study, ROCOF frequency traces provided by the transmission system operators (TSOs) of Ireland were first benchmarked with a full-grid model and in a second step impressed on a model of generators connected to the power grid via a step-up transformer to study transient stability and nonlinear response of the generator. This paper focusses on the ability of nine different synchronous machines to stay connected to the transmission system during severe ROCOF events without losing synchronism.
Źródło:
Archives of Electrical Engineering; 2019, 68, 2; 325-339
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel base strain sensitivity measurement system with steady harmonic excitation
Autorzy:
Ye, Chuwei
Powiązania:
https://bibliotekanauki.pl/articles/2173901.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
base strain sensitivity
piezoelectric accelerometer
steady harmonic excitation
calibration
Opis:
Considering the low accuracy and low efficiency of the traditional calibration method for base strain sensitivity of accelerometers, a novel base strain sensitivity calibration system with steady harmonic excitation is proposed. The required cantilever beam for calibration is driven by an electromagnetic exciter to generate a base strain varying in a steady harmonic pattern. By applying a Wheatstone bridge circuit, the generated strain with low distortion can be measured. The measurement system with a compensation function can automatically calibrate the base strain sensitivity. The amplitude linearity and frequency response characteristics of the base strain sensitivity in two accelerometers are obtained experimentally, and the uncertainty in the results is 2% ( = 2).
Źródło:
Metrology and Measurement Systems; 2022, 29, 4; 751--762
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Verification of the Theoretical Model of Sound Radiation from an Unflanged Duct with Low Mean Flow
Autorzy:
Gorazd, Ł.
Jurkiewicz, J.
Snakowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/178135.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convected wave equation
unflanged cylindrical duct
multimodal
broadband excitation
Opis:
The paper deals with experimental verification of results provided by theoretical approach to the problem of sound radiation from an unflanged duct with mean flow of the medium taking into account existence of all allowable wave modes and, in particular, occurrence of the so-called unstable wave, which results in decay of radiation on and in vicinity of the duct axis. The flow is assumed to be uniform with the source of flow located inside the duct, which is the case frequently occurring in industrial systems. Mathematical considerations, accounting for multimodal and multifrequency excitation and diffraction at the duct outlet, are based on the model of the semi-infinite unflanged hard duct with flow. In the experimental set-up a fan, mounted inside the duct served as the source of flow and noise at the same time modelled as an array of uncorrelated sources of broadband noise, what led to the axisymmetrical shape of the sound pressure directivity characteristics. The theoretical analysis was carried out for the root mean square acoustic pressure in the far-field conditions. Experimental results are presented in the form of the measured pressure directivity characteristics obtained for uniform flow directed inwards and outwards the duct compared to this observed for the zero-flow case. The directivity was measured in one-third octave bands throughout five octaves (500 Hz – 16 kHz) which, for a duct with radius of 0.08 m, corresponds to the range 0.74–23.65 in the reduced frequency ka (Helmholtz number) domain. The results obtained are consistent with theoretical solutions presented by Munt and Savkar, according to whom the weakening of the on-axis and close-to-axis radiation should take place in the presence of medium flow. Experimental results of the present paper indicate that this effect is observed even for the Mach number as low as 0.036.
Źródło:
Archives of Acoustics; 2012, 37, 2; 227-236
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonant characteristics of flow pulsation in pipes due to swept sine constraint
Autorzy:
Pałczyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/175294.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pulsating flow in pipes
sweep sine excitation
amplitude frequency characteristics
Opis:
A fast and easy to use method for analysing the amplitude frequency characteristics of pulsating flow in pipes with a sine sweep input function is presented. The key element is the sweeping excitation of the pulse generator frequency which generates fast whole-spectrum resonance (from 20 Hz to 160 Hz). A case study describes tests conducted into the applicability of the method for research into pulsating flows. First, the test rig is briefly described, along with the main assumptions of the research. Next, theamplitude frequency resonance dueto swept oscillations is estimated for increasing, decreasing and changeable input mass flow rates. These characteristics are approximated based on a second-order transfer function. Following such assumptions, the damping coefficients and resonance frequencies are estimated. The influence of the direction of the frequency sweep method (increasing or decreasing) on the resultant resonance frequency is also investigated.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2016, 133; 131-144
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mutually Orthogonal Golay Complementary Sequences in Synthetic Aperture Imaging Systems
Autorzy:
Trots, I.
Powiązania:
https://bibliotekanauki.pl/articles/178145.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coded excitation
mutually orthogonal Golay codes
synthetic aperture
ultrasound imaging
Opis:
The main objective of this study is to improve the ultrasound image by employing a new algorithm based on transducer array element beam pattern correction implemented in the synthetic transmit aperture (STA) method combined with emission of mutually orthogonal complementary Golay sequences. Orthogonal Golay sequences can be transmitted and received by different transducer elements simultaneously, thereby decreasing the time of image reconstruction, which plays an important role in medical diagnostic imaging. The paper presents the preliminary results of computer simulation of the synthetic aperture method combined with the orthogonal Golay sequences in a linear transducer array. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve the signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work, the 128-element linear transducer array with a 0.3 mm pitch excited by 8-bits Golay coded sequences as well as one cycle at nominal frequencies of 4 MHz were used. The comparison of 2D ultrasound images of the phantoms is presented to demonstrate the benefits of a coded transmission. The image reconstruction was performed using the synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Źródło:
Archives of Acoustics; 2015, 40, 2; 283-289
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel rotor design for a hybrid excited synchronous machine
Autorzy:
Paplicki, P.
Powiązania:
https://bibliotekanauki.pl/articles/141651.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
experimental result
field-weakening
finite element analysis
hybrid excitation
PM machine
rotor design
Opis:
The paper presents three novel rotor design concepts for a three-phase electric controlled permanent magnet synchronous machine (ECPMS-machine) with hybrid excitation. The influence of magnets and flux-barriers arrangement on the magnetic field distribution and field-weakening characteristics of the machine is examined, based on a three-dimensional finite element analysis (3D-FEA). Moreover, a prototype rotor design based on a new rotor concept with a good field-weakening capability is presented in detail. Finally, the experimental results of no-load back electromotive force (back-EMF) waveforms and field-weakening characteristics versus a control coil current of the machine are reported.
Źródło:
Archives of Electrical Engineering; 2017, 66, 1; 29-40
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of scaffolding harmonic excitation
Autorzy:
Bęc, Jarosław
Błazik-Borowa, Ewa
Szer, Jacek
Powiązania:
https://bibliotekanauki.pl/articles/2204503.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
scaffolding
harmonic excitation
dynamic analysis
direct integration
rusztowanie
wzbudzenie harmoniczne
analiza dynamiczna
integracja bezpośrednia
Opis:
Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location. Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 1; art. no. e144577
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of Auditory Filters Based Excitation Patterns for Assessment of Noise Induced Hearing Loss
Autorzy:
Al-Dayyeni, W. S.
Sun, P.
Qin, J.
Powiązania:
https://bibliotekanauki.pl/articles/176368.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
noise induced hearing loss
excitation pattern
basilar membrane motion
auditory filter
noise assessment metrics
Opis:
Noise induced hearing loss (NIHL) as one of the major avoidable occupational related health issues has been studied for decades. To assess NIHL, the excitation pattern (EP) has been considered as one of the mechanisms to estimate the movements of the basilar membrane (BM) in the cochlea. In this study, two auditory filters, dual resonance nonlinear (DRNL) filter and rounded-exponential (ROEX) filter are applied to create two EPs, the velocity EP and the loudness EP respectively. Two noise hazard metrics are proposed based on two EPs to evaluate hazardous levels caused by different types of noise. Moreover Gaussian noise and single-tone noise are simulated to evaluate performances of the proposed EPs and the noise metrics. The results show that both EPs can reflect the responses of the BM to different types of noise. For Gaussian noise there is a frequency shift between the velocity EP and the loudness EP. The results suggest that both EPs can be used for assessment of NIHL.
Źródło:
Archives of Acoustics; 2018, 43, 3; 477-486
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flux-weakening control methods for hybrid excitation synchronous motor
Autorzy:
Mingming, H.
Xinjun, G.
Ping, J.
Quanzhen, H.
Yuping, L.
Na, L.
Powiązania:
https://bibliotekanauki.pl/articles/141662.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hybrid excitation synchronous motor
wide speed range
vector control
flux-weakening control
current distributor
Opis:
The hybrid excitation synchronous motor (HESM), which aim at combining the advantages of permanent magnet motor and wound excitation motor, have the characteristics of low-speed high-torque hill climbing and wide speed range. Firstly, a new kind of HESM is presented in the paper, and its structure and mathematical model are illustrated. Then, based on a space voltage vector control, a novel flux-weakening method for speed adjustment in the high speed region is presented. The unique feature of the proposed control method is that the HESM driving system keeps the q-axis back-EMF components invariable during the flux-weakening operation process. Moreover, a copper loss minimization algorithm is adopted to reduce the copper loss of the HESM in the high speed region. Lastly, the proposed method is validated by the simulation and the experimental results.
Źródło:
Archives of Electrical Engineering; 2015, 64, 3; 427-439
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Continuous-time dynamic system identification with multisine random excitation revisited
Autorzy:
Figwer, J.
Powiązania:
https://bibliotekanauki.pl/articles/229795.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
continuous-time dynamic system identification
multisine random process
system excitation
signal sampling and reconstruction
Opis:
The paper presents a new, revisited and unified approach to a linear continuous-time dynamic single-input single-output system identification using input and output signal samples acquired with a deterministic constant or random sampling interval. The approach is based on a specially designed identification experiment with excitation of the form of a continuous-time multisine random excitation and digital processing of the corresponding signal samples obtained without analogue antialiasing filtration in the case of disturbances satisfying or not satisfying the Shannon's sampling theorem. Properties of the proposed approach are discussed taking into account nonlinearity of the excitation generation and data acquisition systems with a focus on model identification in the case of input and output signal levels comparable with data acquisition system accuracy. Methods reducing influence of the disturbances (including aliasing) as well as nonlinearities of the excitation generation and data acquisition systems on identification results are proposed, too.
Źródło:
Archives of Control Sciences; 2010, 20, 2; 133-149
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of excitation energy transfer in PSII particles of Arabidopsis thaliana mutant clpC1
Autorzy:
Adamiec, M.
Lucinski, R.
Gibasiewicz, K.
Giera, W.
Sipinska, W.
Jackowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/80441.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
excitation energy transfer
Arabidopsis thaliana
clpC1 mutant
polypeptide
time-resolved fluorescence
regulatory protein
chloroplast
apoprotein
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 3
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The acoustic power radiated by a circular membrane excited for vibration both by means of the edge and by external surface load
Autorzy:
Szemela, K.
Rdzanek, W. P.
Rdzanek, W.
Powiązania:
https://bibliotekanauki.pl/articles/176879.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acoustic radiation power
vibrations of a spherical membrane
excitation produced by edge and surface loads
amplitude-phase effects
Opis:
In this paper the acoustic power of the circular membrane, excited both by the edge and external exciting forces uniformly distributed over the whole surface, is examined. Some different amplitudes of exciting factors and some differences between the phases of excitations were considered. It has been assumed that the source of a sound is located in a flat, rigid and infinite baffle and is sourrounded by a lossless and homogeneous fluid medium. The vibrations are axisymmetric and time-harmonic. Employing the Cauchy's theorem of residues and asymptotic formulae for the Bessel functions, the asymptotes for active and reactive power consisting of elementary functions are obtained. The acoustic power radiated by the membrane was shown graphically in terms of the parameters describing both kinds of excitations.
Źródło:
Archives of Acoustics; 2005, 30, 1; 109-119
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 21

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