PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 13

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  rational function
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Optimizing repair/replacement policy if cumulative distribution function of time-to-repair is rational function
Malinowski Jacek
Safety and Reliability of Systems and Processes
|
2023
|
Summer Safety and Reliability Seminar 2023
147--156
EN
A problem of finding the optimal repair/replacement policy of a technical object is under investigation. Depending on the distribution of the time-to-repair and certain cost parameters, a decision is taken whether to repair a failed object or replace it immediately after it fails. If a repair is chosen and it is not completed within a certain period, it is interrupted and the object is replaced by a new one. The optimization task consists in formulating the conditions for choosing between immediate replacement and repair, and deriving the analytical equation for the maximum duration of a repair. The objective function is the expected cost of restoring the object to the operating condition. It is assumed that the cumulative distribution function (CDF) of the time-to-repair is a rational function (a quotient of polynomials). The properties of such CDFs are analyzed and the solutions of several optimization tasks with different CDFs that are rational functions are presented. The issue of fitting the time-to-repair distribution to empirical data is also addressed.
2
Content available Decidability of addition and Frobenius map for polynomials and rational functions
Chompitaki Dimitra, Kamarianakis Manos, Pheidas Thanases
Reports on Mathematical Logic
|
2022
|
Vol. 57
53--60
EN
Let p be a prime number, Fp a finite field with p elements, F an algebraic extension of Fp and z a variable. We consider the structure of addition and the Frobenius map (i.e., x 7→ x p ) in the polynomial rings F[z] and in fields F(z) of rational functions. We prove that any question about F[z] in the structure of addition and Frobenius map may be effectively reduced to questions about the similar structure of the field F. Furthermore, we provide an example which shows that a fact which is true for addition and the Frobenius map in the polynomial rings F[z] fails to be true in F(z). As a consequence, certain methods used to prove model completeness for polynomials do not suffice to prove model completeness for similar structures for fields of rational functions F(z), a problem that remains open even for F = Fp
3
Content available On rational functions related to algorithms for a computation of roots. II
Baran Mirosław
Science, Technology and Innovation
|
2019
|
Vol. 7, no. 4
26--29
EN
We discuss a nice composition properties related to algorithms for computation of N-roots. Our approach gives direct proof that a version of Newton's iterative algorithm is of order 2. A basic tool used in this note are properties of rational function Φ(w; z) = z-w/(z+w), which was used earlier in [1] in the case of algorithms for computations of square roots.
4
Content available On some addition formulas for homographic type functions
Domańska K.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
|
2012
|
Vol. 17
17-24
EN
We deal with the functional equation (so called addition formula) of the form f(x + y) = F(f(x),f(y)), where F is an associative rational function. The class of associative rational functions was described by A. Chéritat [1] and his work was followed by a paper of the author. For function F defined by F(x,y) = ϕ−1(ϕ(x) + ϕ(y)), where ϕ is a homographic function, the addition formula is fulfilled by homographic type functions. We consider the class of the associative rational functions defined by formula F(u,v) =uv αuv + u + v, where α is a fixed real numer.
5
Content available Comparison of transfer functions using estimated rational functions to detect winding mechanical faults in transformers
Bigdeli M., Vakilian M., Rahimpour E.
Archives of Electrical Engineering
|
2012
|
Vol. 61, nr 1
85-99
EN
As it is found in the related published literatures, the transfer function (TF) evaluation method is the most feasible method for detection of winding mechanical faults in transformers. Therefore, investigation of an accurate method for evaluation of the TFs is very important. This paper presents three new indices to compare the transformer TFs and consequently to detect the winding mechanical faults. These indices are based on estimated rational functions. To develop the method, the necessary measurements are carried out on a 1.3 MVA transformer winding, under intact condition, as well as different fault conditions (axial displacement of winding). The obtained results demonstrate the high potential of proposed method in comparison with two other well-known indices. Additionally, two important methods for describing TFs by rational functions are studied and compared in this paper.
6
Content available remote Dirichlet series and gamma function associated with rational functions
Spreafico M.
Bulletin of the Polish Academy of Sciences. Mathematics
|
2010
|
Vol. 58, no 3
189-195
EN
We investigate zeta regularized products of rational functions. As an application, we obtain the asymptotic expansion of the Euler Gamma function associated with a rational function.
7
Content available remote Upraszczanie funkcji wymiernych
Piwowarczyk T.
Czasopismo Techniczne. Elektrotechnika
|
2008
|
R. 105, z. 1-E
51-61
PL
Funkcja wymierna przedstawia w obwodach elektrycznych m.in. stan nieustalony lub transmitancję. Funkcja taka musi być uproszczona przed jej zastosowaniem. Twierdzenie Abela stanowi główny problem podczas upraszczania. Może być on jednak pokonany w specjalnym podejściu. Teoria stanów nieustalonych rozwinięta wokół wielomianów symetrycznych dostarcza odpowiedniej do tego celu algebraicznej procedury. Jest ona wyrażona w klarownym zapisie macierzowym. Konkretny liczbowy przykład dołączony do artykułu ilustruje proponowaną procedurę.
EN
A rational function in electrical circuits represents, among others, a transient state or a transmittance. Such a function must be simplified before it is used in a calculus. The main problem with simplification is the Abel theorem. However, it can be overcome by a special approach. The theory of transient states developed around symmetric polynomials delivers the algebra procedure designed for this purpose. It is expressed in a clear matrix notation. A concrete numerical example of a proposed procedure is enclosed to the article.
8
Content available remote Moc chwilowa w stanie nieustalonym. Reprezentacja w dziedzinie skończonych ciągów liczbowych
Piwowarczyk T.
Czasopismo Techniczne. Elektrotechnika
|
2008
|
R. 105, z. 1-E
41-50
PL
Formułowanie kryteriów wybranych właściwości liniowych obwodów elektrycznych w stanach nieustalonych w większości przypadków nie wymaga funkcji czasowych rozwiązań. Wystarczy poddać analizie odpowiednią transformatę Laplace'a, która, jak wiadomo, jest łatwa do wyznaczenia. Jest to oczywiste w przypadku prądu I(s) oraz napięcia U(s). Analiza mocy chwilowej może być traktowana w sposób analogiczny pod warunkiem, że znamy jej transformatę Laplace'a. W artykule pokazano, jak wyznaczyć transformatę Laplace'a P(s) mocy chwilowej p(t), jeżeli znane są transformaty Laplace'a prądu I(s) oraz napięcia U(s).
EN
In most cases the formulation of the criteria for some chosen properties of linear electrical circuits in transient states does not require the time function solutions. It is sufficient to analyze the appropriate Laplace transform which is known to be easy to obtain. It is obvious in case of the current I(s) and the voltage V(s). The analysis of time power can be treated in an analogous way providing we know its Laplace transform. The article shows how to find the Laplace transform P(s) of the time power p(t) if we know the Laplace transforms of the current I(s) and the voltage U(s).
9
Identification of the rational function of multi-dimensional filters and the synthesis of digital two-dimensional inverse and quasi-inverse filters
Krawczyszyn G.
Poznan University of Technology Academic Journals. Electrical Engineering
|
2007
|
No 53
7-16
EN
The paper aims at presenting the determination method of coefficients of the rational function of multi-dimensiona! filters K-D in the domain of discrete time on the basis of samples of an impulse response. The transmittance is the quotient of two finite multinominals. Interesting solutions can be obtained in the domain of time, in which samples of an approximated signal are used in the algorithm of selection of coefficients for the multi-dimensional filter N-D. The transformation (h→ a) is applied on the basis of such samples, which yields the rational function W(z), which, in turn, is the transmittance of the filter being analysed. Furthermore, the paper also aims to developing a theory concerning digital two-dimensional inverse and quasi-inverse filters. The quasi-inverse filters obtained by way of optimisation permit to select the approximation degree of a resultant system resulting from a cascade connection of a distortion system and a corrective filter. The paper contains formulae, which permit to design a stable quasi-inverse two-dimensional filter on the basis of the existing mathematical model in the form of the transmittance H(z) of a corrected system or its impulse response. The advantage of the formulae is the possibility to select an approximation degree in relation to the ideal inverse filler or the degree of stabilisation.
10
Content available remote Nondeterministic Bimachines and Rational Relations with Finite Codomain
Santean N., Yu S
Fundamenta Informaticae
|
2006
|
Vol. 73, nr 1-2
237-264
EN
Bimachines are important conceptual tools used for the characterization of rational word functions (realized by single-valued transducers). Despite the attention received in the past, these sequential machines are far from being exhaustively studied. A natural question which has not been addressed so far is what family of transductions are realized by bimachines that operate nondeterministically. We show that these machines characterize input-unambiguous (IU) rational transductions, i.e., those transductions that can be written as a composition of rational functions and finite substitutions. Two more families of rational transductions are defined and related in a natural way to IU transductions: input-deterministic transductions and rational transductions with finite codomain (FC). We have shown that FC transductions are recognizable and that they can be expressed as finite union of subsequential functions. Moreover, they can be realized by nondeterministic bimachines. Finally, we have defined the so called restricted nondeterministic bimachines and shown that, surprisingly, they are more powerful than nondeterministic bimachines: they characterize exactly the family of finitely ambiguous rational transductions.
11
Content available remote On Associative Rational Functions
Domańska K.
Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
|
2005
|
Vol. 10
41--65
EN
We deal with the following problem: which rational functions of two variables are associative? We shall determine all of them provided that at least of the coefficients in question vanishes.
12
Content available remote Metoda wyznaczania współczynników funkcji wymiernej filtrów jednowymiarowych 1-D na podstawie próbek odpowiedzi impulsowej
Krawczyszyn G.
Przegląd Elektrotechniczny
|
2004
|
R. 80, nr 6
606-608
PL
Przedmiotem artykułu jest przedstawienie metody wyznaczania współczynników funkcji wymiernej filtrów jednowymiarowych 1-D w dziedzinie czasu dyskretnego na podstawie próbek odpowiedzi impulsowej. Transmitancja ta jest stosunkiem dwóch wielomianów skończonych. W dziedzinie czasu dyskretnego uzyskuje się ciekawe rozwiązania, w których próbki sygnału aproksymowanego są bezpośrednio wykorzystywane w algorytmie doboru współczynników filtra 1-D. Na podstawie tych próbek stosuje się transformację (h->b, a), otrzymując w ten sposób funkcję wymierną W(z), która jest transmitancją analizowanego filtra.
EN
In this paper presents the algorithm of choice rational function coefficients one-dimentional digital filters 1-D in the discreet time domain. The rational function good agrees filters approximation in the constant or discreet time domain. In the article shows simple examples illustrates the algorithm of choice rational function coefficients for the digital filter 1-D.
13
Zastosowanie algorytmu genetycznego i metody Levenberga-Marquardta do aproksymacji indukcyjności widmowych maszyny synchronicznej
Boboń A., Kudła J., Ondrusek C.
Zeszyty Naukowe. Elektryka / Politechnika Śląska
|
1999
|
z. 168
113-124
PL
Przedstawiono sposoby aproksymacji indukcyjności widmowych maszyny synchronicznej za pomocą funkcji wymiernych. Do wyznaczenia parametrów tych funkcji (stałych czasowych), wykorzystano algorytm Levenberga-Marquardta j algorytm genetyczny. Obliczenia przeprowadzono dla generatora synchronicznego o mocy 200 MW, którego transmitancje widmowe zostały wyznaczone na podstawie danych konstrukcyjnych i projektowych.
EN
A procedure of approximation of synchronous machine spectral inductances by complex rational functions has been presented. The Levenberg-Marquardt algorithm and the genetic algorithm has been used to determine parameters (time constants) of the functions being approximated. Calculations have been made for the 200 MW synchronous generator whose spectral transfer functions have been determined basing on the machine design data.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.