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Wyświetlanie 1-15 z 19
Tytuł:
Standard deviation in the simulation of statistical measurements
Autorzy:
Przystupa, Krzysztof
Kolodiy, Zenoviy
Yatsyshyn, Svyatoslav
Majewski, Jacek
Khoma, Yuriy
Petrovska, Iryna
Lasarenko, Serhiy
Hut, Taras
Powiązania:
https://bibliotekanauki.pl/articles/2203365.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
standard deviation
measurement
relaxation time
energy spectrum
Opis:
Is this article simulation of statistical measurements is performed on the basis of which the analysis of the standard deviation of the obtained results is carried out. It is shown that the standard deviation is minimum and independent from measurement duration while an object is in the state of equilibrium. For objects in a stationary non-equilibrium state the standard deviation depends on the duration measurements and the parameters of the state. The influence of these factors on the standard deviation is assessed with equation which includes the relaxation time. The value of the relaxation time is determined by approximating the energy spectrum of the studied signals. The analysis of energy spectra showed that the spectrum of white noise is inherent in objects in equilibrium; the flicker component of the spectrum occurs when the state of the object deviates from equilibrium.
Źródło:
Metrology and Measurement Systems; 2023, 30, 1; 17--30
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lyapunov function based criteria for ship rolling in random beam seas
Autorzy:
Üçer, Erdem
Powiązania:
https://bibliotekanauki.pl/articles/259700.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
random beam sea
wave energy spectrum
Lyapunov function
intact stability criterion
Opis:
The aim of this study is to present a Lyapunov function which can be used to derive an intact stability criterion for a ship in random beam seas. First, the mathematical model of the rolling motion of ships in random beam seas is introduced. The random wave excitation is described by a spectrum which is depended on the wave energy spectrum and the amplitude of the moment of roll. This spectrum is generated by a second order linear filter. Second, the methodology of creating a Lyapunov function is explained briefly. Then, there is outlined the way by which Lyapunov function can be used as the intact stability criterion for a ship. The proposed criterion is derived by considering the weather criteria for German naval vessels. Finally, the coherence of the boundary of safe basin obtained by Lyapunov function with the numerical results obtained by Euler-Maruyama Method is presented. From the results it can be deduced that the Lyapunov function can be used to define an intact stability criterion.
Źródło:
Polish Maritime Research; 2019, 3; 6-14
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Local Turbulent Energy Dissipation Rate in a Vessel Agitated by a Rushton Turbine
Autorzy:
Šulc, R.
Pešava, V.
Ditl, P.
Powiązania:
https://bibliotekanauki.pl/articles/185567.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixing
Rushton turbine
local turbulent energy dissipation rate
energy spectrum
function
fluctuation velocity
mieszanie
turbina Rushtona
rozpraszanie energii
widmo energii
prędkość wahania
Opis:
The scaling of turbulence characteristics such as turbulent fluctuation velocity, turbulent kinetic energy and turbulent energy dissipation rate was investigated in a mechanically agitated vessel 300 mm in inner diameter stirred by a Rushton turbine at high Reynolds numbers in the range 50 000 < Re < 100 000. The hydrodynamics and flow field was measured using 2-D TR PIV. The convective velocity formulas proposed by Antonia et al. (1980) and Van Doorn (1981) were tested. The turbulent energy dissipation rate estimated independently in both radial and axial directions using the one-dimensional approach was not found to be the same in each direction. Using the proposed correction, the values in both directions were found to be close to each other. The relation /(N3·D2) const. was not conclusively confirmed.
Źródło:
Chemical and Process Engineering; 2015, 36, 2; 135-149
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal Voting Rule and Minimization of Total Error Rate in Cooperative Spectrum Sensing for Cognitive Radio Networks
Autorzy:
Ghosh, Samit Kumar
Trankatwar, Sachin Ravikant
Bachan, P.
Powiązania:
https://bibliotekanauki.pl/articles/1839471.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cognitive radio
energy detection
optimization
spectrum sensing
Opis:
In cognitive radio technology, spectrum sensing is essential for detecting spectrum holes which may be allotted to secondary users. In this paper, an optimal voting rule is used for cooperative spectrum sensing while minimizing the total error rate (TER). The proposed spectrum sensing method is more energy-efficient and may be implemented in practice. It is relied upon in an improved energy detector whose utilization depends on the presence or absence of the primary user. Expressions for false alarm and missed detection probabilities are derived in the paper as well. Overall performance is analyzed both for AWGN and Rayleigh fading channels, in the presence of additive white Gaussian noise (AWGN). The optimum voting rule is applied to the cooperative spectrum sensing process in order to identify the optimum number of sensing nodes and the detection threshold. Finally, an energy-efficient spectrum sensing algorithm is proposed, requiring a lower number of cognitive users for a given error bound.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 1; 43-50
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal Voting Rule and Minimization of Total Error Rate in Cooperative Spectrum Sensing for Cognitive Radio Networks
Autorzy:
Ghosh, Samit Kumar
Trankatwar, Sachin Ravikant
Bachan, P.
Powiązania:
https://bibliotekanauki.pl/articles/1839487.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cognitive radio
energy detection
optimization
spectrum sensing
Opis:
In cognitive radio technology, spectrum sensing is essential for detecting spectrum holes which may be allotted to secondary users. In this paper, an optimal voting rule is used for cooperative spectrum sensing while minimizing the total error rate (TER). The proposed spectrum sensing method is more energy-efficient and may be implemented in practice. It is relied upon in an improved energy detector whose utilization depends on the presence or absence of the primary user. Expressions for false alarm and missed detection probabilities are derived in the paper as well. Overall performance is analyzed both for AWGN and Rayleigh fading channels, in the presence of additive white Gaussian noise (AWGN). The optimum voting rule is applied to the cooperative spectrum sensing process in order to identify the optimum number of sensing nodes and the detection threshold. Finally, an energy-efficient spectrum sensing algorithm is proposed, requiring a lower number of cognitive users for a given error bound.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 1; 43-50
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical study of the effect the hydroxyl subgroups on the electronic properties of iso-indene molecule
Autorzy:
Obayes, Abbas Ibrahim
Hasan, Nahida B.
Aboud, Hamed Ibrahem
Mohammed, Mohammed Ahmed
Powiązania:
https://bibliotekanauki.pl/articles/1191969.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
DFT
energy gap
ionization potential
hardness and IR-spectrum
Opis:
In this work, six molecules model are optimized at B3LYP/6-31G** density functional theory. Electronic properties of iso-indene molecules were investigated depending on the three parameters (B3LYP) by density functional theory method. The best geometry for all molecules were investigated at (6-31G**) basis sets. The total energies, energy gaps, ionization potentials, electron affinities and softness were calculated for the studied molecules. Adding the (OH) ion and Nitrogen, Sulfur atoms to the iso-indene molecules leads to decrease the energy gap and the hardness of the studied molecules. The IR-spectra shows the effect of adding the (OH) ion and Nitrogen, Sulfur atoms in the ring on the vibrations of the reference molecule, the electronic properties and IR spectrum for all molecules were investigated by Gaussian 03 program.
Źródło:
World Scientific News; 2016, 50; 49-63
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Suboptimal Approach to Distributed Detection in Cognitive Radio Networks
Autorzy:
Kumari, Shweta
Praveena, Sirimilla
Powiązania:
https://bibliotekanauki.pl/articles/1839473.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cognitive radio
distributed detection
energy detector
myopic policy
spectrum sensing
Opis:
In this paper a dynamic spectrum access (DSA) concept is explored for mitigating the paucity of spectral bandwidth in cognitive radio (CR) for opportunistic, dynamic access of the spectrum without any interference. Dynamic spectrum access schemes are proposed for a distributed cognitive radio network consisting of one secondary user (SU) and many primary users (PUs). The SU has to make decisions for accessing PU channels within discrete time slots. The design of sensing and access strategies that govern channel choice in each slot for near-optimal throughput performance of the SU may be formulated as a partially observable Markov decision process (POMDP). Furthermore, it is considered that the SU incurs a cost whenever it switches to a different channel. The switching cost is expressed in terms of delay, packet loss and packet overhead. In this work, the SU access policy based on a myopic approach is proposed and evaluated.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 1; 32-36
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some characteristic wave energy dissipation patterns along the Polish coast
Autorzy:
Rozynski, G.
Szmytkiewicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/49190.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
energy dissipation
wave energy
statistical parameter
empirical mode decomposition
singular spectrum analysis
Polish coast
Źródło:
Oceanologia; 2018, 60, 4
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Suboptimal Approach to Distributed Detection in Cognitive Radio Networks
Autorzy:
Kumari, Shweta
Praveena, Sirimilla
Powiązania:
https://bibliotekanauki.pl/articles/1839486.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cognitive radio
distributed detection
energy detector
myopic policy
spectrum sensing
Opis:
In this paper a dynamic spectrum access (DSA) concept is explored for mitigating the paucity of spectral bandwidth in cognitive radio (CR) for opportunistic, dynamic access of the spectrum without any interference. Dynamic spectrum access schemes are proposed for a distributed cognitive radio network consisting of one secondary user (SU) and many primary users (PUs). The SU has to make decisions for accessing PU channels within discrete time slots. The design of sensing and access strategies that govern channel choice in each slot for near-optimal throughput performance of the SU may be formulated as a partially observable Markov decision process (POMDP). Furthermore, it is considered that the SU incurs a cost whenever it switches to a different channel. The switching cost is expressed in terms of delay, packet loss and packet overhead. In this work, the SU access policy based on a myopic approach is proposed and evaluated.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 1; 32-36
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Efficient Cooperative Spectrum Sensing Method Using Renyi Entropy Weighted Optimal Likelihood Ratio for CRN
Autorzy:
Shrote, Sandip B.
Poshattiwa, Sadhana D.
Powiązania:
https://bibliotekanauki.pl/articles/24200748.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
cognitive radio
eigen statistics
optimal weight
signal energy
spectrum sensing
Opis:
The main concept behind employing cognitive radio is to enable secondary users (SUs) or unlicensed users to utilize the available spectrum. Spectrum sensing methods detect the existence of primary users (PUs) and have become the main topic of research in the CRN industry and in academia. This paper proposes a new framework based on the Adam gradient descent (Adam GD) algorithm to develop a spectrum sensing mechanism used in CRNs and detecting the availability of free channels. The signal's components are extracted from the received signal and the spectrum is searched for availability which is detected through a fusion center using the proposed algorithm. The proposed Adam GD algorithm attains the maximum detection probability rate and the minimum false alarm probability of 0.71 and 0.39, respectively, for a Rayleigh channel.
Źródło:
Journal of Telecommunications and Information Technology; 2023, 3; 41--48
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
InAs light-to-heavy hole effective mass ratio determined experimentally from mobility spectrum analysis
Autorzy:
Wróbel, Jarosław
Umana-Membreno, Gilberto A.
Boguski, Jacek
Złotnik, Sebastian
Kowalewski, Andrzej
Moszczyński, Paweł
Antoszewski, Jarek
Faraone, Lorenzo
Wróbel, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2204210.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
indium arsenide
effective masses
energy band warping
magnetotransport
mobility spectrum analysis
Opis:
Careful selection of the physical model of the material for a specific doping and selected operating temperatures is a non-trivial task. In numerical simulations that optimize practical devices such as detectors or lasers architecture, this challenge can be very difficult. However, even for such a well-known material as a 5 μm thick layer of indium arsenide on a semiinsulating gallium arsenide substrate, choosing a realistic set of band structure parameters for valence bands is remarkable. Here, the authors test the applicability range of various models of the valence band geometry, using a series of InAs samples with varying levels of p-type doping. Carefully prepared and pretested the van der Pauw geometry samples have been used for magneto-transport data acquisition in the 20-300 K temperature range and magnetic fields up to ±15 T, combined with a mobility spectra analysis. It was shown that in a degenerate statistic regime, temperature trends of mobility for heavy- and light-holes are uncorrelated. It has also been shown that parameters of the valence band effective masses with warping effect inclusion should be used for selected acceptor dopant levels and range of temperatures.
Źródło:
Opto-Electronics Review; 2023, 31, Special Issue; art. no. e144567
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy-based spectrum sensing with copulas for cognitive radios
Autorzy:
Ilgin, F. Y.
Powiązania:
https://bibliotekanauki.pl/articles/201847.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
energy-based sensing
cognitive radio
copula theory
Neyman Pearson
spectrum management
Opis:
In this study, an energy-based spectrum sensing method combined with copula theory is proposed for cognitive radio systems. In the proposed spectrum sensing model, cognitive radio users first make their own local spectrum decision with energy-based spectrum sensing. Then, they forward their decision to the fusion center. In the fusion center, this decision is compared with the threshold value determined by copula theory and global spectrum decision is made. The test statistic at the fusion center were obtained with the Neyman Pearson approach. Thus, the fusion rule was created for the fusion center and necessary simulation studies were performed. According to the results of the simulation studies, the proposed detection method showed better results than the traditional energy based detection method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 4; 829-834
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wyznaczanie charakterystyk wyjściowych modułów fotowoltaicznych z wykorzystaniem sztucznego źródła światła
Determining the Output Characteristics of Photovoltaic Modules Using an Artificial Light Source
Autorzy:
SOBCZYŃSKI, DARIUSZ
BARTMAN, JACEK
Powiązania:
https://bibliotekanauki.pl/articles/455759.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Rzeszowski
Tematy:
panele fotowoltaiczne
energia słońca
charakterystyki widmowe
photovoltaic panels
solar energy
spectrum characteristics
Opis:
W kształceniu inżynierów na kierunku energetyka realizowanym na Wydziale Elektrotechniki i Informatyki Politechniki Rzeszowskiej istotną rolę odgrywa znajomości odnawialnych nośników energii. W artykule przeanalizowano wyznaczanie charakterystyk wyjściowych modułów fotowoltaicznych z wykorzystaniem sztucznego źródła światła. Ważne jest, jaką charakterystykę widmową posiada moduł fotowoltaiczny i jak ta charakterystyka jest pokrywana przez źródło światła. Istotne jest więc zapoznanie studentów ze zjawiskami, jakie zachodzą podczas pracy wymienionych modułów. Normy dotyczące określania parametrów modułów fotowoltaicznych determinują natężenie promieniowania oraz temperatury modułu w tzw. standardowych warunkach pomiarów.
In the education of engineers during the course of Power Engineering being carried out by the Faculty of Electrical and Computer Engineering of the Rzeszow University of Technology, knowledge of renewable energy sources retrieve an important role. In this article, the determina-tion of the output characteristics of photovoltaic modules employing an artificial light source was analysed. It is important what the spectral characteristics of photovoltaic module look like and how this characteristic is covered by the light source. Therefore, it is important to familiarize students with the phenomena that occur during the work of the photovoltaic modules. The standards for measure the parameters of solar modules determine the irradiation intensity and module tempera-ture in so-called standard measurement conditions.
Źródło:
Edukacja-Technika-Informatyka; 2018, 9, 3; 327-333
2080-9069
Pojawia się w:
Edukacja-Technika-Informatyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Spectra Of Variants Of The Corona Of Two Graphs And Some New Equienergetic Graphs
Autorzy:
Adiga, Chandrashekar
Rakshith, B.R.
Powiązania:
https://bibliotekanauki.pl/articles/31341147.pdf
Data publikacji:
2016-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
spectrum
corona
neighbourhood corona
edge corona
energy of a graph
equienergetic graphs
Opis:
Let G and H be two graphs. The join G ∨ H is the graph obtained by joining every vertex of G with every vertex of H. The corona G ○ H is the graph obtained by taking one copy of G and |V (G)| copies of H and joining the i-th vertex of G to every vertex in the i-th copy of H. The neighborhood corona G★H is the graph obtained by taking one copy of G and |V (G)| copies of H and joining the neighbors of the i-th vertex of G to every vertex in the i-th copy of H. The edge corona G ◇ H is the graph obtained by taking one copy of G and |E(G)| copies of H and joining each terminal vertex of i-th edge of G to every vertex in the i-th copy of H. Let G1, G2, G3 and G4 be regular graphs with disjoint vertex sets. In this paper we compute the spectrum of (G1 ∨ G2) ∪ (G1 ★ G3), (G1 ∨ G2) ∪ (G2 ★ G3) ∪ (G1 ★ G4), (G1 ∨ G2) ∪ (G1 ○ G3), (G1 ∨ G2) ∪ (G2 ○ G3) ∪ (G1 ○ G4), (G1 ∨ G2) ∪ (G1 ◇ G3), (G1 ∨ G2) ∪ (G2 ◇ G3) ∪ (G1 ◇ G4), (G1 ∨ G2) ∪ (G2 ○ G3) ∪ (G1 ★ G3), (G1 ∨ G2) ∪ (G2 ○ G3) ∪ (G1 ◇ G4) and (G1 ∨ G2) ∪ (G2 ★ G3) ∪ (G1 ◇ G4). As an application, we show that there exist some new pairs of equienergetic graphs on n vertices for all n ≥ 11.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 1; 127-140
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical procedures and their practical application in PV module analyses. Part 3, Parameters of atmospheric transparency : determining and correlations
Autorzy:
Rodziewicz, T.
Rajfur, M.
Powiązania:
https://bibliotekanauki.pl/articles/1818226.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
solar radiation spectrum
sky clearness index
diffused component content index
solar energy
photovoltaics
Opis:
The presented article examines aspects of a PV module testing using natural sunlight in outdoor conditions. The article discusses the physical sense of indexes: atmosphere purity, diffused component content, beam clear sky index. Procedures for their determination are given in relation to both instantaneous and daily values. Their close connection with the values of solar irradiance spectral distribution such as Average Photon Energy and Useful Fraction is demonstrated, as well as their usefulness in module testing in outdoor conditions. Their influence on the conversion of modules made from various absorbers and various technologies is demonstrated.
Źródło:
Opto-Electronics Review; 2020, 28, 1; 15--34
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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