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1
Content available Singular quasilinear convective systems involving variable exponents
Moussaoui Abdelkrim, Nabab Dany, Vélin Jean
Opuscula Mathematica
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2024
|
Vol. 44, no. 1
105--134
EN
The paper deals with the existence of solutions for quasilinear elliptic systems involving singular and convection terms with variable exponents. The approach combines the sub-supersolutions method and Schauder’s fixed point theorem.
2
Content available On the regularity of solution to the time-dependent p-Stokes system
Berselli Luigi C., Ruzicka Michael
Opuscula Mathematica
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2020
|
Vol. 40, no. 1
49--69
EN
n this paper we consider the time evolutionary p-Stokes problem in a smooth and bounded domain. This system models the unsteady motion or certain non-Newtonian incompressible fluids in the regime of slow motions, when the convective term is negligible. We prove results of space/time regularity, showing that first-order time-derivatives and second-order space-derivatives of the velocity and first-order space-derivatives of the pressure belong to rather natural Lebesgue spaces.
3
Content available Nonlinear measures in posturography compared to linear measures based on yoga poses performance
Błażkiewicz MIchalina
Acta of Bioengineering and Biomechanics
|
2020
|
Vol. 22, no. 4
15--21
EN
Yoga is known as a type of exercise that combines physical, mental and spiritual aspects. There has not been much research on the postural control in various yoga poses. The aim of this study was to examine CoP regularity in both yoga instructors and novices during the performance of four yoga poses, and to verify the sensitivity of linear and nonlinear methods for assessing postural stability. Methods: The dynamic characteristics of CoP fluctuations were examined using linear and nonlinear methods on a group of 22 yoga instructors (Y) and 18 age-matched non-practitioners of yoga (NY). The study involved maintaining a balance for 20 seconds while performing four yoga poses. Results: Conventional analysis of CoP trajectories showed that NY and Y exhibited similar control of postural sway, as indicated by similar CoP path-length and area values observed in both groups. These results suggest that the special balance yoga training received by Y may not have an impact on less challenging balance conditions, such as the poses used in this experiment. Interestingly, nonlinear dynamical analysis of CoP showed that Y exhibited less CoP regularity and more complex signal than NY, as evidenced by higher values of sample entropy and fractal dimension. Conclusions: The results shed light on the surplus values of CoP trajectories in the nonlinear dynamical analysis to gain further insight into the mechanisms involved in posture control.
4
Content available remote Analiza punktualności i regularności kursowania autobusów komunikacji miejskiej na wybranych trasach Szczecina i Polic
Regulski Paweł, Abramek Karol Franciszek
Autobusy : technika, eksploatacja, systemy transportowe
|
2019
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R. 20, nr 1-2
26--34
PL
W artykule przedstawiono analizę punktualności i regularności kursowania autobusów komunikacji miejskiej na wybranych trasach Szczecina i Polic. Badania zostały przeprowadzone w maju 2018 roku w dni robocze w godzinach popołudniowego szczytu przewozowego na podstawie danych z Centralnego Systemu Zarządzania Komunikacją Miejską. Obejmowały one dwie linie autobusowe. W ramach badań wskazano m.in. miejsca zwiększonego natężenia ruchu drogowego.
EN
The article presents an analysis of punctuality and regularity of public transport buses on selected routes of Szczecin and Police. Research were carried out in May 2018 on working days in the afternoon transport peak and in November 2018 on working days before the afternoon peak, during the afternoon transport peak and after the afternoon peak based on data from the Central Public Transport Management System They included two bus lines. Research indicated, among others, places of increased road traffic.
5
Content available Generalized PI observer design for descriptor linear system
Wang Xin-Tao, Yu Hai-Hua
Archives of Control Sciences
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2019
|
Vol. 29, No. 4
585--601
EN
A kind of generalized proportional-integral (GPI) observer for descriptor linear systems is introduced. We first propose two complete parametric solutions to generalized Sylvester matrix equation corresponding to the left eigenvector matrices in the case of Jordan form. Then a parametric design approach for the observer is presented. The proposed method provides all parametric expression of the gain matrices and the corresponding finite left eigenvector matrix and guarantees the regularity and impulse-freeness of the expanded error system. Two numerical examples are given to explain the design procedure and illustrate the effectiveness of the proposed method.
6
Content available Distributed controllability of one-dimensional heat equation in unbounded domains: The Green's function approach
Khurshudyan Asatur Zh.
Archives of Control Sciences
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2019
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Vol. 29, No. 1
57--71
EN
We derive exact and approximate controllability conditions for the linear one-dimensional heat equation in an infinite and a semi-infinite domains. The control is carried out by means of the time-dependent intensity of a point heat source localized at an internal (finite) point of the domain. By the Green’s function approach and the method of heuristic determination of resolving controls, exact controllability analysis is reduced to an infinite system of linear algebraic equations, the regularity of which is sufficient for the existence of exactly resolvable controls. In the case of a semi-infinite domain, as the source approaches the boundary, a lack of L2-null-controllability occurs, which is observed earlier by Micu and Zuazua. On the other hand, in the case of infinite domain, sufficient conditions for the regularity of the reduced infinite system of equations are derived in terms of control time, initial and terminal temperatures. A sufficient condition on the control time, heat source concentration point and initial and terminal temperatures is derived for the existence of approximately resolving controls. In the particular case of a semi-infinite domain when the heat source approaches the boundary, a sufficient condition on the control time and initial temperature providing approximate controllability with required precision is derived.
7
Content available Analysis and assessment of the regularity of mass urban passenger transport in the conditions of the city of ruse
Pencheva V., Tsekov A., Georgiev I., Kostadinov S.
Transport Problems
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2018
|
T. 13, z. 3
109--118
EN
One of the quality indicators of the transport service in passenger transport is the regularity of the movement of vehicles. Apart from the planned traffic intervals, it depends on a number of factors related to the traffic conditions of the public transport in the locality (intensity and composition of the traffic flow, passenger traffic structure, traffic lights regime, atmospheric conditions, etc.). The paper assesses the regularity of mass urban passenger transport traffic in the conditions of the city of Ruse, Bulgaria, by probing the estimation of the arrival intervals of the means of transport at the stops along a given route.
8
Ocena jakości usługi transportowej w publicznym transporcie zbiorowym w Krakowie : aspekt regularności i komfortu
Bryniarska Z.
Logistyka
|
2015
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nr 3
591--601, CD 1
PL
Ważnymi z punktu widzenia pasażerów cechami jakości usług publicznego transportu zbiorowego w mieście jest obok punktualności regularność kursowania i komfort przemieszczania. Organizator transportu zbiorowego w mieście powinien systematycznie monitorować ważne dla pasażerów cechy jakości i podejmować decyzje zmierzające do dostosowania jakości świadczonych usług do oczekiwań pasażerów. W artykule przedstawiono zasady i wyniki oceny jakości usługi transportowej uzyskiwane w latach 1997-2005 ze szczególnym uwzględnieniem regularności i komfortu. Przedstawiono również wartości tych wskaźników obliczone dla okresów późniejszych, przy wykorzystaniu reguł stosowanych w systemie SKUT. Wyznaczono strukturę procentową wskaźnika względnego zapełnienia pojazdów komunikacji tramwajowej i autobusowej w dni robocze, soboty i niedziele.
EN
There are several characteristics of urban public transport service quality that are important from the point of view of passengers. One of them is punctuality, but regularity and travel comfort are very often stressed by passengers as well. The organizer of public transport in the city should regularly monitor especially these characteristics of quality that are the most important for passengers. Moreover, he should make decisions designed to adjust the quality of services provided to the expectations of passengers. The article presents results of evaluation of transport service quality obtained in 1997-2005 with particular emphasis on regularity and comfort. Additionally it presents values of these indicators calculated for later periods, using the rules used in the system SKUT. The structure of relative number of passengers in vehicles (tramways and buses) in relation to capacity of vehicles on working days, Saturdays and Sundays have been estimated.
9
Content available Regularity, pointwise completeness and pointwise generacy of descriptor linear electrical circuits
Kaczorek T.
Poznan University of Technology Academic Journals. Electrical Engineering
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2014
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No. 77
9--28
EN
The regularity, pointwise completeness and pointwise generacy of descriptor linear electrical circuits composed of resistances, capacitances, inductances and voltage (current) sources are addressed. It is shown that every descriptor electrical circuit is a linear system with regular pencil. Conditions for the pointwise completeness and pointwise generacy of the descriptor linear electrical circuits are established. The considerations are illustrated by examples of descriptor electrical circuits.
10
Content available remote On the coset category of a skew lattice
Pita-Costa J.
Demonstratio Mathematica
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2014
|
Vol. 47, nr 3
539--554
EN
Skew lattices are noncommutative generalizations of lattices. The coset structure decomposition is an original approach to the study of these algebras describing the relation between its rectangular classes. In this paper, we will look at the category determined by these rectangular algebras and the morphisms between them, showing that not all skew lattices can determine such a category. Furthermore, we will present a class of examples of skew lattices in rings that are not strictly categorical, and present sufficient conditions for skew lattices of matrices in rings to constitute ^-distributive skew lattices.
11
Content available Sequential optimization for semilinear divergent hyperbolic equation with a boundary control and state inequality constraint
Gavrilov V. S., Sumin M. I.
Control and Cybernetics
|
2014
|
Vol. 43, no. 2
183--226
EN
An optimal control problem with a state constraint of inequality type and with dynamics described by a semilinear hyperbolic equation in divergence form with the non-homogeneous boundary condition of the third kind is considered. The state constraint contains a functional parameter that belongs to the class of continuous functions and occurs as an additive term. We study the properties of solutions of linear hyperbolic equations in divergence form with measures in the original data and compute the first variations of functionals on the basis of a so-called two-parameter needle variation of controls. We consider the necessary conditions for minimizing sequences in an optimal control problem with a pointwise in time state constraint of inequality type and with dynamics described by a semilinear hyperbolic equation in divergence form with the non-homogeneous boundary condition of the third kind. For the parametric optimization problem, we also consider regularity and normality conditions stipulated by the differential properties of its value function.
12
Content available Analysis of the regularity, pointwise completeness and pointwise generacy of descriptor linear electrical circuits
Kaczorek T.
Computer Applications in Electrical Engineering
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2014
|
Vol. 12
1--20
EN
A method for analysis of the regularity, pointwise completeness and pointwise generacy of descriptor linear electrical circuits composed of resistances, capacitances, inductances and voltage (current) sources is proposed. It is shown that every descriptor electrical circuit is a linear system with regular pencil. Conditions for the pointwise completeness and pointwise generacy of the descriptor linear electrical circuits are established. The considerations are illustrated by examples of descriptor electrical circuits.
13
Content available remote Erratum to : On the coset structure of a skew lattice
Pita Costa J.
Demonstratio Mathematica
|
2013
|
Vol. 46, nr 2
245--246
14
Content available remote On the coset structure of a skew lattice
Pita-Costa J.
Demonstratio Mathematica
|
2011
|
Vol. 44, nr 4
673-692
EN
The class of skew lattices can be seen as an algebraic category. It models an algebraic theory in the category of sets where the Green's relation D is a congruence describing an adjunction to the category of lattices. In this paper we will discuss the relevance of this approach, revisit some known decompositions and relate the order structure of a skew lattice with its coset structure that describes the internal coset decomposition of the respective skew lattice.
15
Content available remote On how to use expert judgements in regularity analyses to obtain good predictions.
Hjorteland A., Aven T.
Zagadnienia Eksploatacji Maszyn
|
2007
|
Vol. 42, nr 3
157-169
EN
The purpose of regularity analysis is to assess future deliveries of production and transportation systems, such as oil and gas installations. When conducting such analysis, models are developed reflecting the performance of various equipment, for example compressors and pumps. To assess the equipment performance there is a need for relevant konwledge, including observed data and expert judgements. One of the challenges in regularity analyses is to assess uncertainties for the large number of quantities in the models being used. These quantities are either, observable quantities such as lifetimes or repair times, or statistical expected values or probabilities, such as MTTF or MTTR. The purpose of this paper is to present and discuss a practical approach for such assessments using the combination of expert judgements and hard data. The approach is based on a Bayesian framework, with focus on prediction and uncertainty assessments of observable quantities.
PL
Celem analiz regularności jest oszacowanie wielkości przyszłych dostaw surowców za pomocą systemów produkcyjnych i transportowych, takich jak instalacje naftowe i gazowe. Przeprowadzając taką analizę buduje się modele opisujące działanie różnorodnego wyposażenia, np. sprężarek lub pomp. Aby ocenić pewność działania wyposażenia technicznego niezbędna jest odpowiednia wiedza, obejmująca zaobserwowane wielkości i opinie ekspertów. Jednym z wyzwań w analizach regularności jest oszacowanie niepewności w warunkach dużej liczby elementów składowych w zastosowanych modelach. Te elementy składowe mogą być wielkościami obserwowalnymi, takimi jak czas do uszkodzenia lub czas naprawy, mogą być też wielkościami statystycznymi, wyrażonymi jako wartości oczekiwane, bądź prawdopodobieństwa, na przykład MTTF (średni czas do uszkodzenia) lub MTTR (średni czas naprawy). Celem niniejszego artykułu jest przedstawienie i przedyskutowanie praktycznych sposobów dokonywania takich analiz w oparciu o kombinację opinii eksperckich i twardych danych. Proponowane podejście oparte jest na modelu Bayesowskim, przy czym skupiono się na predykcji i ocenie niepewności dla wielkości obserwowalnych.
16
Continuity properties of the stree tensor in the 3-dimensional Ramberg/Osgood model
Bildhauer. M., Fuchs M.
Journal of Applied Analysis
|
2007
|
Vol. 13, nr 2
209-233
EN
We discuss the weak form of the Ramberg/Osgood equations (also known as the Norton/Hoff model) for nonlinear elastic materials on a 3-dimensional domain and show that the stress tensor is Hoelder continuous on an open subset whose complement is of Lebesguemeasure zero. We also give an estimate for the Hausdorff-dimension of the singular set.
17
Content available remote Interpreted Trajectories
Domaratzki M., Rozenberg G., Salomaa K.
Fundamenta Informaticae
|
2006
|
Vol. 73, nr 1-2
81-97
EN
We introduce generalized trajectories where the individual symbols are interpreted as operations performed on the operand words. The various previously considered trajectory-based operations can all be expressed in this formalism. It is shown that the generalized operations can simulate Turing machine computations. We consider the equivalence problem and a notion of unambiguity that is sufficient to make equivalence decidable for regular sets of trajectories under nonincreasing interpretations.
18
Content available remote Higher separation axioms in generalized closure spaces
Stadler B. M. R., Stadler P. F.
Annales Societatis Mathematicae Polonae. Seria 1: Commentationes Mathematicae
|
2003
|
[Z] 43(2)
257-273
EN
The hierarchy of separation axioms that is familiar from topological spaces generalizes to spaces with an isotone and expansive closure function. Neither additivity nor idempotence of the closure function must be assumed.
19
Content available Finite-dimensional representations of the value functions of some optimal control problems
Mirica S.
Control and Cybernetics
|
2002
|
Vol. 31, no 3
779-801
EN
In this survey we analyze the possibility of obtaining information on regularity and irregularity properties of the value functions of some optimal control problems from their more precise description as marginal functions of finite-dimensional type, in terms of certain "generalized characteristic flows" which, in turn, may be constructed using either necessary optimality conditions (PMP-Pontryagin's Minimum Principle), whenever applicable, or suitable extensions of Cauchy's Method of Characteristics for the associated Hamilton-Jacobi-Bellman equation. This type of representation, which may be justified either by the application of PMP "combined" with existence theorems or by the application of a suitable verification theorem of Dynamic Programming type, not only facilitates numerical computation of the value function but also may allow identification of its discontinuity points, non-differentiability points, propagation of singularities, etc. ; this approach is illustrated with three significant examples from classical Calculus of Variations.
20
Content available remote Grade exploratory methods applied to some medical data sets
Pleszczyńska E., Szczesny W.
Biocybernetics and Biomedical Engineering
|
2002
|
Vol. 22, no. 1
17-30
EN
Two sets of medical categorical data are analyzed by means of grade exploratory methods, based on one fundamental procedure called the grade correspondence analysis (GCA). A special attention is put on visualization. The paper is a contribution to discussion concerning visualization of categorical data, which is going on in contemporary statistical literature.
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