Wyniki wyszukiwania - Biblioteka Nauki

1

When a constant subsequence implies ultimate periodicity

100%

Miska P.

Bulletin of the Polish Academy of Sciences. Mathematics

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2019

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tom Vol. 67, no. 1

41--51

EN

We show a curious property of sequences given by the recurrence a0 = h1(0), an = f(n) an-1 + h1 (n) h2 (n)n, n > 0, where f, h1, h2 ϵ Z[X]. Namely, if the sequence (akn+l)n ϵ N is constant for some k ϵ N+ and l ϵ N, then either (a2n+l)n ϵ N = (0)n ϵ N and (a2n)n ϵ N is a geometric progression, or (an)n ϵ N is ultimately periodic with period dividing 2.

2

Stokhasticheskie modeli obespechenija rabotosposobnosti sel'skokhozjajjstvennykh mashin

100%

Rogovskijj I.

Motrol. Motoryzacja i Energetyka Rolnictwa

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2014

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tom 16

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nr 3

3

Further instances of periodicity in May's host parasitoid equation

100%

Sizer W. S.

Fasciculi Mathematici

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2010

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tom Nr 44

115-121

EN

May’s host parasitoid equation is the difference equation (1) ...[wzór] We show that for each &slpha; there is a number k such that, whenever n > k, equation (1) has a one cycle periodic solution of period n. We also give some results on two cycle periodic solutions.

4

Asymptotic Analysis of a Semelparous Species Model

100%

Rudnicki R. , Wieczorek R.

Fundamenta Informaticae

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2010

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tom Vol. 103, nr 1-4

219-233

EN

We study a non-linear age-structured discrete-time population model and give necessary and sufficient conditions for stability of a positive stationary point. In the case of semelparous species we show that the population converges locally to a population consisted only of individuals at one age. It means that the long-time behaviour of the population depends only on an one-dimensional transformation g. If the reproduction age is an even number we prove that the positive stationary point is unstable and numerical simulations suggest that in this case almost all trajectories behave asymptotically as trajectories corresponding to g.

5

On a system of rational difference equations ...[wzór]

100%

Liu K. , Li P. , Zhong W.

Fasciculi Mathematici

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2013

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tom Nr 51

105--114

EN

In this paper, we are concerned with a three- dimensional system of rational difference equations. We present solutions of the system in an explicit way and obtain the asymptotical behavior of solutions according to initial values. We also give sufficient conditions of existing four-period solutions.

6

Conditions for periodic vibrations in a symmetric n-string

100%

Gauthier C.

Open Mathematics

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2008

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tom 6

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nr 2

287-300

EN

A symmetric N-string is a network of N ≥ 2 sections of string tied together at one common mobile extremity. In their equilibrium position, the sections of string form N angles of 2π/N at their junction point. Considering the initial and boundary value problem for small-amplitude oscillations perpendicular to the plane of the N-string at rest, we obtain conditions under which the solution will be periodic with an integral period.

7

On asymptotically periodic-like motions in flows

100%

Gryszka K.

Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica

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2018

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tom 17

8

Trends and periodicity in the longest instrumental rainfall series for the area of most extreme rainfall in the world, Northeast India

100%

Prokop P. , Walanus A.

Geographia Polonica

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2003

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tom 76

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nr 2

9

Reachable sets concept - a general abstract analysis

88%

Terlikowski T.

Control and Cybernetics

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2003

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tom Vol. 32, no 4

803-817

EN

A control problem over the infinite time horizon for periodical system is considered. Our aim is to analyze a special concept of solving problems of this type, based on the known idea of reachable sets. We try to consider this concept in a more general manner than it was done in earlier works and to find what is really essential in it. The algorithm corresponding to the proposed general description is presented.

10

On the solutions of a class of difference equations systems

88%

Elabbasy E. , El-Metwally H. , Elsayed E.

Demonstratio Mathematica

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2008

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tom Vol. 41, nr 1

109-122

EN

In this paper we discuses the periodic solutions of particular cases of the following general system of difference equations [...]. The results obtained are new and contained as special cases some other results.

11

ω-rewriting the Collatz problem

88%

Scollo G.

Fundamenta Informaticae

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2005

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tom Vol. 64, nr 1-4

405-416

EN

The Collatz problem is comprised of two distinct, separate questions: existence of eventually periodic Collatz reductions with a nontrivial period, and existence of period-free Collatz reductions. This paper introduces a few distinct, related formalizations of the Collatz dynamics as term rewriting systems, using elementary concepts from the theory of state transition dynamics. Some of the subject systems act on finite terms, whereas others rewrite terms that are endowed with a countable, recursively defined structure. The latter presents a convenient framework for the investigation of extensions of the Collatz dynamics to dense systems.

12

On P Systems and Almost Periodicity

88%

Bernardini F. , Gheorghe M. , Manca V.

Fundamenta Informaticae

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2005

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tom Vol. 64, nr 1-4

29-42

EN

The study of P systems as a mathematical model for biological systems is an important research topic in the area of membrane computing. In this respect, the detection of periodicity and almost periodicity as aspects of the system dynamics seems to be of particular relevance for understanding many biological processes and their related phenomena. This paper introduces specific notions of periodicity and almost periodicity for (infinite) sequences of multisets, which are used to describe the dynamics of P systems. Specifically, a variant of P systems, called P systems with resources, is considered where the rules always consume a certain amount of resources, which are provided in the form of a periodic input sequence of multisets. It is then shown that P systems with resources are computationally complete (when halting computations are considered) and that, in general, they can generate sequences of multisets that are not even almost periodic (once the constraint of having halting computation is released). However, if P systems with resources are restricted to be deterministic, it is shown that a characterization of the behaviour of a particular class of P systems with resources can be obtained in terms of almost periodicty.

13

On the solutions of the recursive sequence xx+1 = ...[wzór]

75%

Karatas R.

Fasciculi Mathematici

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2010

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tom Nr 45

37-45

EN

In this paper we study the solutions of the difference equation x + ...[wzór] for n = 0,1,2, ... where a, x_-(2k+1), x_-(2k), x_-(2k-1), ..., x₀ are the real numbers such that x₀x_{-(k+1) ≠ a, x_-1x_-(k+2) ≠ a, x_-2x_{-(k+3) ≠ a. ..., x_-kx_{-(2k+1) ≠ a and k is a natural number.}}}

14

Cykliczność przepływu w zlewni rzeki Raby. Część I, Przepływy miesięczne

75%

Węglarczyk S. , Kędra M.

Czasopismo Techniczne. Środowisko

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2006

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tom R. 103, z. 2-Ś

189-202

PL

W niniejszym artykule omówiono zjawisko okresowości zmian przepływu w zlewni rzeki Raby. Przeprowadzona analiza dotyczyła cykliczności przepływu w cieku głównym i na jego dopływach, a dokonana została na podstawie szeregów czasowych średnich miesięcznych przepływów obliczonych dla 16 przekrojów wodowskazowych badanej zlewni. Za pomocą analizy spektralnej Fouriera wykryto wiele cykli, wśród których dominujący okazał się cykl 12-miesięczny. Nie był on jednak istotny w kilku przypadkach, co mogło być spowodowane antropopresją. Spośród pozostałych cykli niewątpliwe wydają się tylko cykle ok. 6- i 15-miesięczne.

EN

This article presents an overview of issues concerning the cyclical nature of flow in the Raba river catchment. The analysis was based on series of mean monthly flows at 16 gauging stations in that catchment. By means of Fourier analysis, many cycles were found, of which the 12-month cycle turned out to prevail. However, for a few stations, that cycle was not significant, which mighty be caused by anthropogenic influence. Out of other significant cycles, only 6- and 15-month cycles seem to be unquestionable.

15

Subword Balance in Binary Words, Languages and Sequences

75%

Salomaa A.

Fundamenta Informaticae

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2007

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tom Vol. 75, nr 1-4

4690482-4690482

EN

We investigate binary words and languages having a balanced structure of (scattered) subwords. We introduce a "difference function" D for binary words. For D=0, the resulting language is properly context-sensitive. Parikh matrices constitute a useful technical tool in the study, we investigate also the independence of their entries. The investigation is extended to concern w-words and periodicity. For the Fibonacci word, the D-values are in many ways connected with the Fibonacci numbers.

16

Macroeconomic News Effects on the Stock Markets in Intraday Data

75%

Będowska-Sójka B.

Central European Journal of Economic Modelling and Econometrics

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2013

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nr 4

17

Metoda kompleksowej oceny sezonowości na przykładzie kopalin pozyskiwanych odkrywkowo

75%

Obrzut M.

Górnictwo Odkrywkowe

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2004

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tom R. 46, nr 7/8

97-102

PL

Zjawisko cykliczności występuje w wielu dziedzinach życia ludzkiego. Niejednokrotnie stwarza problemy natury organizacyjnej, które z kolei wymagają przeciwdziałań. W artykule zaproponowano kompleksowy, w porównaniu z dotychczasowymi, model wyznaczania cykliczności zjawisk, zwracając równocześnie uwagę na konieczność każdorazowego wyznaczania okresu T. Artykuł zawiera przykłady obliczeniowe do metody.

EN

Periodicity phenomenon occurs in many domains of human life. Many times it creates organizational problems, which require counteraction. Complex model of effects periodicity determination was proposed in the article taking into consideration the necessity of determination of period Ton case-by-case basis. Article contains analytical examples to the method.

18

Zmienność temperatury powietrza w północnej Polsce

75%

Banaszkiewicz B. , Panfil M.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2003

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tom Vol. 12, No. 1

91--97

EN

The paper presents analysis results of variability of air temperature in northem Poland. The comparison monthly mean values of air temperature of the 1951-1990 period with adequate values of 1881-1930 and 1931-1960 revealed that values of the 1951-1990 years are higher on the all investigated area in June and also generally in period from October to December (Figure 1). Monthly mean air temperature in the years of 1951-1990 revealed often inereasing tendency in winter months, March and May; how ever descending trend of air temperature occurred generally from June to September (Figure 2). The observed changes of mean values of monthly air temperature in Koszalin are in prevailing cases representative for all area of northem Poland. The spectral (Fourier) analysis of mean annual air temperature in Koszalin of the period 1851-1990 was done also. The data were filtered (it was used the 4235H filter), the linear trend and means values were removed from the series before the analysis. The periodogram values was computed using Hamming window (5). Four dominant cycles found in Fourier analysis were used to predict the temperature for the 1851-2030 period (Figure 4).

19

Cyclic processes scheduling

75%

Bocewicz G. , Banaszak Z.

Applied Computer Science

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2010

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tom Vol. 6, no 2

41--70

EN

In everyday practice cyclic scheduling problems, especially timetabling ones arise in different application and service domains, e.g., class, train, crew timetabling, and so on. In many cases, e.g., caused by assumed slot size, imposing integer domain results in Diophantine character of problems considered. In that context some classes of cyclic scheduling problems can be seen as non-decidable (undecidable) ones. That means, since system constraints (i.e., parameter domains) determine its behavior (e.g., the space of feasible schedules), hence both system structure configuration and desired schedule have to be considered simultaneously. So, cyclic scheduling problem solution requires that the system structure configuration must be determined for the purpose of processes scheduling, yet scheduling must be done to devise the system configuration. In that context, this contribution provides discussion of some solubility issues concerning cyclic processes dispatching problems.

20

Periodic dynamics in a model of immune system

75%

Bodnar M. , Foryś U.

Applicationes Mathematicae

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2000

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tom 27

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nr 1

113-126

EN

The aim of this paper is to study periodic solutions of Marchuk's model, i.e. the system of ordinary differential equations with time delay describing the immune reactions. The Hopf bifurcation theorem is used to show the existence of a periodic solution for some values of the delay. Periodic dynamics caused by periodic immune reactivity or periodic initial data functions are compared. Autocorrelation functions are used to check the periodicity or quasiperiodicity of behaviour.