Wyniki wyszukiwania - BazTech

1

The impact of two independent gaussian white noises on the behavior of a stochastic epidemic model

Yavuz Mehmet, Boulaasair Lahcen, Bouzahir Hassane, Diop Mamadou Abdoul, Benaid Brahim

Journal of Applied Mathematics and Computational Mechanics

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2024

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Vol. 23, nr 1

121-134

EN

The aim of this paper is to investigate a stochastic SIS (Susceptible, Infected, Susceptible) epidemic model in which the disease transmission coefficient and the death rate are subject to random disturbances. Using the convergence theorem for local martingales and solving the Fokker-Planck equation associated with the one-dimensional stochastic differential equation, we demonstrate that the disease will almost surely persist in the mean. In the case of global asymptotic stability of the endemic equilibrium for a SIS deterministic epidemic model, we formulate suitable conditions guaranteeing that the stochastic SIS model has a unique ergodic stationary distribution. Furthermore, we deal with the exponential extinction of the disease. Finally, some numerical simulations are provided to illustrate the obtained analytical results.

2

Development of voluntary qualities of student youth in the process of physical culture and sports

Syndykova Iiyna

Zeszyty Naukowe Wyższej Szkoły Technicznej w Katowicach

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2022

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T. 15

75--82

EN

The article presents the results of a theoretical study, the purpose of which was to analyze the basic principles of development of volitional qualities of student youth as a holistic systemic individual psychological characteristics in the process of physical culture and sports. Scientific novelty lies in the theoretical substantiation of volitional qualities of students in the process of physical culture and sports, it is in the process of physical education clearly defines the goals and content of activities, tools and methods that affect the development of determination, perseverance, endurance, determination, courage, ie. form a habit of showing the willful efforts of young people. The concept of „will” from the point of view of philosophers, psychologists and teachers is described. The modern definition of will is consistent with the fact that it is a conscious self-regulation of human activities, which provides overcoming obstacles and difficulties on the way to his goal. It is noted that in the process of physical education a necessary condition for the formation of the child’s will is to master the techniques, increase the level of physical fitness. At the same time, psychological and pedagogical methods of stimulation should be taken into account: praise, awards and other techniques that increase students’ interest in classes and contribute to a significant increase in selfconfidence. The volitional efforts in the process of physical culture and sports activities are analyzed and five of their types are distinguished: volitional efforts at muscular tensions; volitional efforts under stress; volitional efforts when performing actions to overcome fatigue; strong-willed efforts aimed at adhering to the regime; volitional efforts are aimed at overcoming feelings of fear.

PL

W artykule przedstawiono wyniki teoretycznego badania, którego celem była analiza głównych zasad rozwoju siły woli uczniów, jako całościowych, systemowych cech indywidualno-psychologicznych, w procesie wychowania fizycznego i sportu. Nowatorstwo naukowe polega na badaniu teoretycznego ugruntowania siły woli uczniów w procesie wychowania fizycznego i sportu. To właśnie w procesie wychowania fizycznego, cele i treści działań, środki i metody, wpływają na realizację celów kształcenia wytrwałości, wytrzymałości. Determinacja, odwaga są jasno określone, tj. tworzą nawyk okazywania młodym ludziom silnej woli. Pojęcie „woli” jest scharakteryzowane z punktu widzenia filozofów, psychologów i nauczycieli. Współczesna definicja woli jest zgodna z faktem, że jest to świadoma samoregulacja przez osobę swoich działań, zapewniająca pokonywanie przeszkód i trudności na drodze do celu. Zwraca się uwagę, że w procesie wychowania fizycznego warunkiem koniecznym kształtowania się woli dziecka jest opanowanie różnych technik, służących podnoszeniu poziomu sprawności fizycznej. Jednocześnie należy wziąć pod uwagę psychologiczne i pedagogiczne metody stymulacji: pochwały, nagrody i inne metody, które zwiększają zainteresowanie uczniów zajęciami, przyczyniając się do znacznego wzrostu pewności siebie. Przeanalizowano wysiłki wolicjonalne w procesie kultury fizycznej i aktywności sportowej, wyróżniając pięć ich typów: wysiłek wolicjonalny podczas napięcia mięśniowego; wolicjonalne wysiłki podczas zwracania uwagi; wolicjonalne wysiłki podczas wykonywania działań, mających na celu przezwyciężenie zmęczenia; dobrowolne wysiłki, ktore mają na celu utrzymanie reżimu; wysiłki wolicjonalne służące przezwyciężeniu uczucia strachu.

3

On the detection and attribution of streamflow persistence of rivers in Peninsular India

Adarsh Sankaran, Nourani Vahid, Johnson Ashly, Jayan Anjali, Archana Devarajan Sindhu, Amrutha Asokan Jeeja

Acta Geophysica

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2022

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Vol. 70, no 3

1373--1383

EN

Persistence expressed by hurst exponent (H) is estimated for streamflow of 122 stations in the basins of Peninsular India by three methods at different aggregation scales (daily, monthly mean, monthly and annual maximum). Mean H values indicated long term persistence (LTP) and the data of more than 70% stations showed LTP for other temporal resolutions. H displayed negative correlation with time series length, mean annual and specific mean discharges, while no significant correlation with catchment area. Positive dependence was found between persistence of streamflow and different climatic attributes (rainfall; maximum, mean and minimum temperature) for daily and annual maximum datasets.

4

Persistence of the thin layers of transition metal carbides in contact with liquid NiBSi alloy

Bober Mariusz, Senkara Jacek, Wendler Bogdan

Welding Technology Review

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2021

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R. 93, nr 1

5--12

EN

The article presents the results of study on interaction between the liquid NiBSi alloy and solid, thin, micrometer-range layers of transition metal carbides of IVB - VIB groups of the periodic table. The reactive magnetron sputtering method was adopted to deposit of these layers on molybdenum substrates. Carbide layers are destroyed in contact with liquid alloy by dissolving, intensified by the penetration of the liquid along the coating ‒ substrate interface. The strong interaction between liquid NiBSi and both the carbide ceramics and the refractory metal substrate was revealed. The effect intensity differs somewhat for both tested carbide groups: VIB (relatively fast) and IVB (less intense).

PL

W artykule przedstawiono wyniki badań oddziaływania ciekłego stopu NiBSi z litymi, cienkimi, mikrometrowymi warstwami węglików metali przejściowych IVB – VIB grup układu okresowego pierwiastków. Do nanoszenia tych warstw na podłożach molibdenowych adoptowano metodę reaktywnego rozpylania magnetronowego. Warstwy węglików ulegają destrukcji w trakcie kontaktu z ciekłym stopem poprzez ich rozpuszczanie, intensyfikowane penetracją cieczy po granicy powłoka - podłoże. Świadczy to o silnym oddziaływaniu cieczy NiBSi zarówno z ceramiką węglikową, jak i podłożem z metalu trudnotopliwego. Efekt ten jest zróżnicowany dla węglików metali grup VIB (stosunkowo szybki) i IVB (mniej intensywny).

5

Target-oriented Petri Net Synthesis

Best Eike, Devillers Raymond, Erofeev Evgeny, Wimmel Harro

Fundamenta Informaticae

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2020

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Vol. 175, nr 1-4

97--122

EN

When a Petri net is synthesised from a labelled transition system, it is frequently desirable that certain additional constraints are fulfilled. For example, in circuit design, one is often interested in constructing safe Petri nets. Targeting such subclasses of Petri nets is not necessarily computationally more efficient than targeting the whole class. For example, targeting safe nets is known to be NP-complete while targeting the full class of place/transition nets is polynomial, in the size of the transition system. In this paper, several classes of Petri nets are examined, and their suitability for being targeted through efficient synthesis from labelled transition systems is studied and assessed. The focus is on choice-free Petri nets and some of their subclasses. It is described how they can be synthesised efficiently from persistent transition systems, summarising and streamlining in tutorial style some of the authors’ and their groups’ work over the past few years.

6

Multifractal description of streamfow and suspended sediment concentration data from Indian river basin

Adarsh S., Dharan Drisya S., Nandhu A. R., Vishnu B. Anand, Mohan Vysakh K., Wątorek M.

Acta Geophysica

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2020

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Vol. 68, no. 2

519--535

EN

This study investigated the multifractality of streamfow data of 192 stations located in 13 river basins in India using the multifractal detrended fuctuation analysis (MF-DFA). The streamfow datasets of diferent river basins displayed multifractality and long-term persistence with a mean exponent of 0.585. The streamfow records of Krishna basin displayed least persistence and that of Godavari basin displayed strongest multifractality and complexity. Subsequently, the streamfow-sediment links of fve major river basins were evaluated using the novel multifractal cross-correlation analysis (MFCCA) method of cross-correlation studies. The results showed that the joint persistence of streamfow and total suspended sediments (TSS) is approximately the mean of the persistence of individual series. The streamfow displayed higher persistence than TSS in 60% of the stations while in majority of stations of Godavari basin the trend was opposite. The annual cross-correlation is higher than seasonal cross-correlation in majority of stations but at these time scales strength of their association difers with river basin.

7

Analysis and Synthesis of Weighted Marked Graph Petri Nets : Exact and Approximate Methods

Devillers Raymond, Hujsa Thomas

Fundamenta Informaticae

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2019

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Vol. 169, nr 1-2

1--30

EN

Numerous real-world systems can be modeled with Petri nets, which allow a combination of concurrency with synchronizations and conflicts. To alleviate the difficulty of checking their behaviour, a common approach consists in studying specific subclasses. In the converse problem of Petri net synthesis, a Petri net of some subclass has to be constructed efficiently from a given specification, typically from a labelled transition system (lts) describing the behaviour of the desired net. In this paper, we focus on a notorious subclass of persistent Petri nets, the weighted marked graphs (WMGs), also called generalised (or weighted) event (or marked) graphs or weighted T-nets. In such nets, edges have multiplicities (weights) and each place has at most one ingoing and one outgoing transition. Although extensively studied in previous works and benefiting from strong results, both their analysis and synthesis can be further investigated. We provide new behavioural properties of WMGs expressed on their reachability graph, notably backward persistence and strong similarities between any two sequences sharing the same starting state and the same destination state. Besides, we design a general synthesis procedure aiming at the WMG class. Finally, when no solution to the synthesis problem exists, i.e., when the given lts is not WMG-solvable, we show how to construct a WMG whose reachability graph is a minimal over-approximation of the given lts.

8

Synthesis of Live and Bounded Persistent Systems

Best E., Devillers R.

Fundamenta Informaticae

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2015

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Vol. 140, nr 1

39--59

EN

This paper presents a dedicated Petri net synthesis algorithm for the case that a transition system is finite, live, and persistent. In particular, the paper delineates exactly when and how a structurally persistent net may be constructed, by crystallising, out of a general region-theoretic approach, a minimised set of simplified systems of linear inequalities. This extends previous results where reversibility, instead of liveness, played an important role.

9

Persistent and Nonviolent Steps and the Design of GALS Systems

Fernandes J., Koutny M., Mikulski Ł, Pietkiewicz-Koutny M., Sokolov D., Yakovlev A.

Fundamenta Informaticae

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2015

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Vol. 137, nr 1

143--170

EN

A concurrent system is persistent if throughout its operation no activity which became enabled can subsequently be prevented from being executed by any other activity. This is often a highly desirable (or even necessary) property; in particular, if the system is to be implemented in hardware. Over the past 40 years, persistence has been investigated and applied in practical implementations assuming that each activity is a single atomic action which can be represented, for example, by a single transition of a Petri net. In this paper we investigate the behaviour of GALS (Globally Asynchronous Locally Synchronous) systems in the context of VLSI circuits. The specification of a system is given in the form of a Petri net. Our aim is to re-design the system to optimise signal management, by grouping together concurrent events. Looking at the concurrent reachability graph of the given Petri net, we are interested in discovering events that appear in ‘bundles’, so that they all can be executed in a single clock tick. The best candidates for bundles are sets of events that appear and re-appear over and over again in the same configurations, forming ‘persistent’ sets of events. Persistence was considered so far only in the context of sequential semantics. In this paper, we move to the realm of step based execution and consider not only steps which are persistent and cannot be disabled by other steps, but also steps which are nonviolent and cannot disable other steps. We then introduce a formal definition of a bundle and propose an algorithm to prune the behaviour of a system, so that only bundled steps remain. The pruned reachability graph represents the behaviour of a re-engineered system, which in turn can be implemented in a new Petri net using the standard techniques of net synthesis. The proposed algorithm prunes reachability graphs of persistent and safe nets leaving bundles that represent maximally concurrent steps.

10

Persistence of some iterated processes

Baumgarten C.

Probability and Mathematical Statistics

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2014

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Vol. 34, Fasc. 2

293--316

EN

We study the asymptotic behaviour of the probability that a stochastic process (Zt)t ≥ 0 does not exceed a constant barrier up to time T (a so-called persistence probability) when Z is the composition of two independent processes (Xt)t ϵ I and (Yt)t ≥ 0. To be precise, we consider (Zt)t ≥ 0 defined by Zt = X ◦ |Yt| if I = [0, ∞) and Zt = X ◦ Yt if I = R. For continuous self-similar processes (Yt)t ≥ 0, the rate of decay of persistence probability for Z can be inferred directly from the persistence probability of X and the index of self-similarity of Y. As a corollary, we infer that the persistence probability for iterated Brownian motion decays asymptotically like T−1/2. If Y is discontinuous, the range of Y possibly contains gaps, which complicates the estimation of the persistence probability. We determine the polynomial rate of decay for X being a Lévy process (possibly two-sided if I = R) or a fractional Brownian motion and Y being a Lévy process or random walk under suitable moment conditions.

11

On reconstruction of the Ito-like equation from persistent time series

Czechowski Z.

Acta Geophysica

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2013

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Vol. 61, no. 6

1504--1521

EN

The Langevin equation with finite-range persistence was introduced as a macroscopic model of various geophysical phenomena. The modified histogram procedure (MHP) of reconstruction of the equation from time series was proposed. An efficiency of MHP was tested on artificial persistent time series (with short and long-tail distributions) generated by different Ito-like equations. For an exemplary geophysical time series, the appropriate Ito-like equation was reconstructed.

12

Trwanie form

Barnaś J.

Czasopismo Techniczne. Architektura

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2011

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R. 108, z. 4-A/2

21--23

PL

Architektury nie buduje jeden człowiek, ale jest ona dziełem wielu pokoleń. To nieco przekształcone stwierdzenie Gaudiego oddaje sens i zasadę trwania dzieła architektonicznego. Dzieła architektury również w czasach współczesnych nie tracą na aktualności. Dzięki zaangażowaniu współczesnych architektów przekształcając je, można uzyskać interesujące efekty przestrzenne, a także pozyskać inwestorów gotowych sfinansować przedsięwzięcie Upływający czas i następujące zmiany dodają nowych znaczeń zastosowanym rozwiązaniom.

EN

Architecture is not created by a single person, but by entire generations. This slightly altered statement by Gaudi illustrates the meaning of an architectural work's persistance. Works of architecture do not lose their worth in modern times. Thanks to the commitment of contemporary architects these works can be modified and interesting spatial effects can be obtained, which can be used to attract investors ready to finance these endeavors. The passage of time and the ongoing changes add further meaning to these design solutions.

13

A mathematical model of HIV-1 infection including the saturation effect of healthy cell proliferation

Kouche M., Ainseba B.

International Journal of Applied Mathematics and Computer Science

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2010

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Vol. 20, no 3

601-612

EN

In this paper we derive a model describing the dynamics of HIV-1 infection in tissue culture where the infection spreads directly from infected cells to healthy cells trough cell-to-cell contact. We assume that the infection rate between healthy and infected cells is a saturating function of cell concentration. Our analysis shows that if the basic reproduction number does not exceed unity then infected cells are cleared and the disease dies out. Otherwise, the infection is persistent with the existence of an infected equilibrium. Numerical simulations indicate that, depending on the fraction of cells surviving the incubation period, the solutions approach either an infected steady state or a periodic orbit.

14

The effect of Atpolan 80 EC on atrazine residues in the soil

Swarcewicz M., Skórska E., Paździoch W.

Polish Journal of Chemical Technology

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2007

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Vol. 9, nr 3

5-8

EN

The persistence of atrazine residues in soils may have an effect on the contamination of the ground water or surface water. Besides the active ingredients, pesticide formulations contain many other compounds called adjuvants. One of them is the Atpolan 80 EC which belongs to the group of oil mineral adjuvants used as lank-mix. The utilization of a fraction of paraffin oil 1113 is one of the examples of utilising waste as the component of Atpolan 80 EC in agriculture. When the Atpolan concentration comprised 1.25% (v/v), the atrazine degradation rate decreased in the sandy loam and muck soil. The half-life of atrazine increased over a period of 40 or 57 days, depending on the type of the soil. The least significant effect was caused by Atpolan concentration at 0.25 and 0.75%. This result points at the capability of limiting atrazine run-off and leaching down the soil profile. Each ingredient of the pesticide, besides having the overall ability to distribute between different phases, also demonstrates some single compound behaviour. This paper shows our current understanding of the factors that influence the adjuvant performance and their potentially complex interactions with the pesticide.

15

Boundedness and persistence of solutions of a nonlinear difference equation

Stević S.

Demonstratio Mathematica

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2003

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Vol. 36, nr 1

99--104

EN

In this paper we obtain sufficient conditions for the boundedness as well ;is for the unboundedness of the positive solutions of the difference equation xn+1=f(xn,...,xn-k+1), n=0,1,2,...,where k is a positive integer and the initial conditions x-k+1, X-k+2,...x0 are arbitrary positive numbers.

16

Extinction, Weak Extinction and Persistence in a Discrete, Competitive Lotka-Volterra Model

Chan D. M., Franke J. E.

International Journal of Applied Mathematics and Computer Science

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2000

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Vol. 10, no 1

7-36

EN

In a discrete Lotka-Volterra model, the set of points where a population remains unchanged over one generation is a hyperplane. Examining the relative position of these hyperplanes, we give sufficient conditions for a groupof species to drive another species to extinction. Further using these hyperplanes, we find necessary and sufficient conditions where every w-limit point of the model has at least one species missing. Building on the workof Hofbauer et al. (1987) involving permanence, we obtain a sufficient condition for one or more species to persist. Additionally, in the presence of extinction occurring, we take these persistence results and the previously mentioned extinction results and extend them to subsystems of the full model. Finally, we combine the ideas of persistence and weak extinctionto obtain another extinction result.