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Wyświetlanie 1-15 z 19
Tytuł:
New type of Piezoresistive Pressure Sensors for Environments with Rapidly Changing Temperature
Autorzy:
Tykhan, M.
Ivakhiv, O.
Teslyuk, V.
Powiązania:
https://bibliotekanauki.pl/articles/221026.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pressure
sensor
non-stationary
temperature
Opis:
The theoretical aspects of a new type of piezo-resistive pressure sensors for environments with rapidly changing temperatures are presented. The idea is that the sensor has two identical diaphragms which have different coefficients of linear thermal expansion. Therefore, when measuring pressure in environments with variable temperature, the diaphragms will have different deflection. This difference can be used to make appropriate correction of the sensor output signal and, thus, to increase accuracy of measurement. Since physical principles of sensors operation enable fast correction of the output signal, the sensor can be used in environments with rapidly changing temperature, which is its essential advantage. The paper presents practical implementation of the proposed theoretical aspects and the results of testing the developed sensor.
Źródło:
Metrology and Measurement Systems; 2017, 24, 1; 185-192
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disinflation and Reliability of Underlying Inflation Measures
Autorzy:
Deryugina, Elena
Ponomarenko, Alexey
Powiązania:
https://bibliotekanauki.pl/articles/2075645.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
underlying inflation
non-stationary dynamic factor model
Russia
Opis:
We estimated a non-Stationary dynamic factor model and used it to generate artificial episodes of disinflation (permanent changes in the mean inflation rate). These datasets were used to test the forecasting abilities of alternative underlying inflation indicators (i.e. measures that capture sustained movements in inflation extracted from information in a disaggregated set of price data). We found that the out of sample forecast errors of the benchmark underlying inflation measures (based on unobserved trend extraction) are more severely affected by disinflation than the alternative simpler methods (based on exclusion or re-weighting approaches). We also show that a non-stationary dynamic factor model may be employed for the extraction of the unobserved trend to be used as an underlying inflation measure.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2020, 1; 91-111
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Virtual Reality Could Improve Exercise Performance on a Stationary Bike
Autorzy:
Kowal, Marta
Piskorz, Joanna
Czub, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/2129930.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stationary bike
cycling
optic flow
physical training
Virtual Reality
Opis:
The present study aimed to investigate the effects of manipulating visual information about one’s movement in Virtual Reality (VR) during physical training on a stationary bike. In the first experiment, the participants’ (N=30) task was to cycle on a stationary bike while embodying a virtual avatar. Fifteen participants experienced the Slow condition, in which a virtual avatar cycled at the constant speed of 15km/h, while the other fifteen participants experienced the Fast condition, in which a virtual avatar cycled at the constant speed of 35km/h. In the second experiment, we tested whether introducing agency (i.e., linking real-life cycling speed with the cycling speed of a virtual avatar), would improve exercise performance. Participants (N=31) experienced counterbalanced conditions: Faster optic flow (avatar’s speed was 15% faster than the participants’ real cycling speed), and Slower optic flow (avatar’s speed was 15% slower than the participants’ real cycling speed). Results showed that all participants increased their cycling speed when experiencing altered cycling speed of a virtual avatar compared with their baselines, but in the first experiment, participants cycled faster in the faster optic flow condition, while in the second experiment, when participants controlled the virtual avatar’s cycling speed, there were no differences between the Fast and Slow conditions. Participants described the cycling in VR as a pleasant experience. The present study suggests that the addition of Virtual Reality during exercise training may increase cycling performance.
Źródło:
Polish Psychological Bulletin; 2021, 52, 4; 365-372
0079-2993
Pojawia się w:
Polish Psychological Bulletin
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vector analysis of the current commutation in PM BLDC drives
Autorzy:
Buja, G.
Menis, R.
Keshri, R.
Powiązania:
https://bibliotekanauki.pl/articles/201920.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
PM BLDC drive
current commutation
stationary plane vector analysis
Opis:
The vector approach in either stationary or synchronous plane is commonly used for the analysis of the AC drives like induction and PM brushless AC drives whilst it has been hardly ever used for the PM brushless DC (BLDC) drives. A possible reason is that they require injection of square-wave currents into the motor phases, which are non-sinusoidal in nature. Recently, the PM BLDC drives have been analyzed by the help of the vector approach in the stationary plane. This paper applies such an approach to an in-depth analysis of the operation of the PM BLDC drives during the current commutations, illustrating the potentialities of the approach in giving a better insight into the current transients and the ensuing torque characteristics. At last, two voltage control strategies proposed to eliminate the torque ripple due to the current commutations are considered, showing that they can be readily understood by the vector approach.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 829-836
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive inventory control system for material items with continuous non-stationary demand
Autorzy:
Krajčovič, M.
Plinta, D.
Powiązania:
https://bibliotekanauki.pl/articles/406736.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inventory control
algorithm
non-stationary demand
joint replenishment
inventory analysis
Opis:
This paper describes an algorithm of dynamic inventory control system for large numbers of material items with continuous non-stationary demand. It uses principles of pull inventory control systems, statistical inventory analysis and joint replenishment inventory systems. This algorithm was processed in software module (VBA for Excel) and applied in practice. The target of described algorithm is to keep an optimum inventory level and optimum customer service level in terms of inventory control of items with non-stationary demand.
Źródło:
Management and Production Engineering Review; 2014, 5, 1; 11-20
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stationary supercapacitor energy storage operation algorithm based on neural network learning system
Autorzy:
Jefimowski, W.
Nikitenko, A.
Drążek, Z.
Wieczorek, M.
Powiązania:
https://bibliotekanauki.pl/articles/200935.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stationary energy storage
operation algorithms
machine learning
supervised learning
prediction
Opis:
The paper proposes to apply an algorithm for predicting the minimum level of the state of charge (SoC) of stationary supercapacitor energy storage system operating in a DC traction substation, and for changing it over time. This is done to insure maximum energy recovery for trains while braking. The model of a supercapacitor energy storage system, its algorithms of operation and prediction of the minimum state of charge are described in detail; the main formulae, graphs and results of simulation are also provided. It is proposed to divide the SoC curve into equal periods of time during which the minimum states of charge remain constant. To predict the SoC level for the subsequent period, the learning algorithm based on the neural network could be used. Then, the minimum SoC could be based on two basic types of data: the first one is the time profile of the energy storage load during the previous period with the constant minimum SoC retained, while the second one relies on the trains’ locations and speed values in the previous period. It is proved that the use of variable minimum SoC ensures an increase of the energy volume recovered by approximately 10%. Optimum architecture and activation function of the neural network are also found.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 4; 733-738
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Microstructure and Mechanical Properties of Al 3003 Alloy Weld by Stationary Shoulder Friction Stir Welding Process
Autorzy:
Jung, Woo-Chul
Park, Joo-Heon
Yoon, Sang-Min
Kim, Young Kyun
Powiązania:
https://bibliotekanauki.pl/articles/2203728.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stationary shoulder friction stir welding
aluminum 3003 alloy
microstructure
mechanical properties
Opis:
The lap joint welding of Al 3003 alloy by stationary shoulder friction stir welding (SSFSW) was performed under the conditions of tool rotation and welding speed, and it was confirmed that the welding was performed under all conditions. The tunnel defects and pores were formed in the weld zone at the lowest tool rotation and welding speed, and it is increased, the weld surface has been improved. At the same tool rotation speed at the welding speed is increased, the grain size was refined in the stir zone (SZ) and thus the hardness increased by about 14% compared to the base metal. The tensile shear strength is measured to be 10 kN or more under most conditions, and in the 4000 rpm with high heat input, the shear tensile strength was measured relatively lower than other conditions due to excessive heat input of the material.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 1; 113--118
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound Radiation from a Roundabout
Autorzy:
Piddubniak, O.
Piddubniak, N.
Powiązania:
https://bibliotekanauki.pl/articles/177962.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
roundabout
car sound radiation
stationary phase method
acoustic pressure
power flow density
Opis:
Sound propagation from the vehicles moving on the city roundabout, with taking into account the wind is investigated. Solution of the problem for one moving sound source is found by means of the integral Fourier transforms extended over space variables and time. Inverse transforms are calculated approximately, using a stationary phase method and iterative technique. The solution for a general problem is obtained as a superposition of many partial solutions. The numerical analysis of noise characteristics is performed for the three-way Korfanty roundabout case in Łódz.
Źródło:
Archives of Acoustics; 2010, 35, 3; 437-456
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Impedance Boundary Conditions applied to solving nonlinear electrodynamic systems
Autorzy:
Pawłowski, S.
Plewako, J.
Powiązania:
https://bibliotekanauki.pl/articles/141489.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nonlinear electrodynamics
Surface Impedance Boundary Conditions
harmonic fields
quasi-stationary fields
skin effect
Opis:
The paper presents a method for solving electromagnetic field problems by applying impedance boundary conditions for systems including conducting bodies of nonlinear magnetic properties in an excited harmonic field. Three types of impedance boundary conditions were derived. A procedure for computing surface impedance based on the transfer matrix is proposed. This procedure has been tested by comparing computational results to calculations where time function distortions were considered, and to the experimental data.
Źródło:
Archives of Electrical Engineering; 2017, 66, 2; 433-446
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental identification of rotating and stationary damping in a cracked rotor system with an offset disc
Autorzy:
Roy, Dipendra K.
Tiwari, Rajiv
Powiązania:
https://bibliotekanauki.pl/articles/140313.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rotating (internal) damping
stationary (external) damping
gyroscopic effect
switching crack
unbalance
full-spectrum
Opis:
In the rotor system, depending upon the ratio of rotating (internal) damping and stationary (external) damping, above the critical speed may develop instability regions. The crack adds to the rotating damping due to the rubbing action between two faces of a breathing crack. Therefore, there is a need to estimate the rotating damping and other system parameters based on experimental investigation. This paper deals with a physical model based an experimental identification of the rotating and stationary damping, unbalance, and crack additive stiffness in a cracked rotor system. The model of the breathing crack is considered as of a switching force function, which gives an excitation in multiple harmonics and leads to rotor whirls in the forward and backward directions. According to the rotor system model considered, equations of motion have been derived, and it is converted into the frequency domain for developing the estimation equation. To validate the methodology in an experimental setup, the measured time domain responses are converted into frequency domain and are utilized in the developed identification algorithm to estimate the rotor parameters. The identified parameters through the experimental data are used in the analytical rotor model to generate responses and to compare them with experimental responses.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 4; 447-474
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized feedback stability for periodic linear time-varying, discrete-time systems
Autorzy:
Orłowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/201050.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
discrete-time systems
time-varying systems
non-stationary systems
feedback stability
frequency analysis
Opis:
The paper proposes a novel method for feedback stability evaluation for linear time-varying, discrete-time control systems. It is assumed that the time-varying system can be described by the general discrete-time, time-varying state space model and by the equivalent linear input-output (transfer) operator. The method extends feedback stability concepts for systems given in a general linear time-varying, discrete-time form, not only in the Lurie form. In the paper selected short-time stability concepts are employed for inference about feedback stability of systems defined on an infinite time-horizon. Theoretical considerations are complemented by numerical examples.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 1; 171-178
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of the Contact Layer in Continuous Casting of thin Metal Rods
Wpływ warstwy kontaktu na proces odlewania ciągłego cienkich prętów metalowych
Autorzy:
Lipnicki, Z.
Pantoł, K.
Weigand, B.
Powiązania:
https://bibliotekanauki.pl/articles/351935.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
continuous casting
solidification stationary front
contact layer
odlewanie ciągłe
stacjonarny front krzepnięcia
warstwa kontaktowa
Opis:
An analytical heat transfer model has been development and applied for calculating the shape of the solid thickness profile for continuous casting of thin metal rods. The stationary solidification front relative to the crystallizer was received from superposition of the motions of the liquid metal flow in the axial direction and the solidifying metal in the radial direction. The shape of the solidified crust depends on several parameters. The influence of the contact layer between the frozen crust and the internal surface of a crystallizer on the solidification process is also studied. The results are presented as an analytical model and are graphically shown for different selected parameters.
W pracy bada się analitycznie i oblicza się kształty frontów krzepnięcia przy odlewaniu ciągłym cienkich metalowych prętów. Określono stacjonarny front krzepnięcia względem krystalizatora przez superpozycję dwóch ruchów: przepły wu ciekłego metalu w kierunku pionowym i rozprzestrzenianie się frontu krzepnięcia w kierunku promieniowym. Szczególną uwagę zwrócono na opór cieplny warstwy kontaktu między metalem i powiercznią wewnętrzną krystalizatora. Wykazano zależność kształtu frontu krzepnięcia od parametrów termodynamicznych i przepływowych metalu. Wyniki badań wybranych metali przedstawiono w formie graficznej.
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 1; 167-172
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical Modelling of Sound Radiation from a T Junction of City Roads in Windy Conditions
Autorzy:
Piddubniak, O.
Piddubniak, N.
Powiązania:
https://bibliotekanauki.pl/articles/176734.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
T junction of city roads
traffic noise propagation
stationary phase method
acoustic pressure
power flow density
Opis:
The sound radiation from vehicles travelling on the city roads with T junction was considered. The wind effect on acoustic field was taken into account. The solution of this problem was found with the help of the integral Fourier transforms and stationary phase method as the superposition of solutions for the cases of vehicles moving along the straight roads and roads with right-angle bend. As an example, the numerical analysis of traffic noise characteristics was carried out for the T junction city road on one of streets in the town of Łódź (Poland).
Źródło:
Archives of Acoustics; 2016, 41, 3; 543-558
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Instantaneous Frequency Estimation of Multi-Component Non- Stationary Signals using Fourier Bessel series and Time-Varying Auto Regressive Model
Autorzy:
Ravi Shankar Reddy, G.
Rao, R.
Powiązania:
https://bibliotekanauki.pl/articles/226382.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
basis functions
Fourier-Bessel expansion
instantaneous frequency
multi component non stationary signal
Time-varying Auto Regressive model
Opis:
In this paper, we propose a novel technique for Instantaneous frequency (IF) estimation of multi component non stationary signals using Fourier Bessel Series and Time-Varying Auto Regressive (FB-TVAR) model. In the proposed technique, the Fourier-Bessel (FB) expansion decomposes the multicomponent non stationary signal into a number of monocomponent signals and TVAR model is used to model each monocomponent signal. In TVAR modeling approach the time varying parameters are expanded as a linear combination of basis functions. In this paper, the TVAR parameters are expanded by a discrete cosine basis functions. The maximum likelihood estimation algorithm for model order selection in TVAR models is also discussed. The Instantaneous frequency (IF) is extracted from the time-varying parameters by calculating the angles of the estimation error filter polynomial roots. The estimation of the TVAR parameters of a multicomponent signal requires the inversion of a large covariance matrix, while the projected technique (FB-TVAR) requires the inversion of a number of comparatively small covariance matrices with better numerical stability properties. Simulation results are presented for three component discrete Amplitude and Frequency modulated (AM-FM)signal.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 365-376
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of hall currents on thermal instability of dusty couple stress fluid
Autorzy:
Aggarwal, A. K.
Verma, A.
Powiązania:
https://bibliotekanauki.pl/articles/240229.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
couple-stress fluid
dust particles
hall currents
stationary convection
oscillatory modes
magnetic field
ziarna pyłu
konwekcja
pole magnetyczne
Opis:
In this paper, effect of Hall currents on the thermal instability of couple-stress fluid permeated with dust particles has been considered. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For the case of stationary convection, dust particles and Hall currents are found to have destabilizing effect while couple stresses have stabilizing effect on the system. Magnetic field induced by Hall currents has stabilizing/destabilizing effect under certain conditions. It is found that due to the presence of Hall currents (hence magnetic field), oscillatory modes are produced which were non-existent in their absence.
Źródło:
Archives of Thermodynamics; 2016, 37, 3; 3-18
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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