Wyniki wyszukiwania - Biblioteka Nauki

1

An analysis of discrete-continuous mechanical systems with conjugations

100%

Sękala A.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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tom Vol. 49, nr 2

360--368

EN

Purpose: The main purpose of this work is developing a methodology, using non-classical methods, of modelling the complex mechanical systems with the continuous and discrete-continuous distribution of parameters. A simple task of dynamics can be solved by using this method, without limitations deriving from the type and number of the elements of a mechanical system. Design/methodology/approach: By using the non-classical methods of modelling, it was possible to develop a method of determining the matrices (flexibilities) of multi-link vibration mechanical systems with the continuous distribution of parameters that are able to perform longitudinal and flexural vibrations. The method is focused on broadening graphs method by mechanical systems and improving their description and design methods so that the mathematical formalism can reflect the essence of the problem involved in the designation of dynamic characteristics of such systems. Findings: The knowledge of the dynamic characteristics of a system determined for any inputs and outputs in form of kinematic and dynamic excitations is underlying the determination of frequency characteristics of the class of the systems under consideration. Research limitations/implications: The class of the systems considered refers to investigating into the dynamic and vibration characteristics of mechanical systems with the discrete-continuous distribution of parameters performing small vibrations around the adopted state of equilibrium. Practical implications: The presented method of this study is that the main point can be the introduction to e.g. additional kinematic excitations in form of a function of speed and accelerations or extending the method presented to cover the investigation of non-linear systems. Originality/value: The modelling and analysis of discrete-continuous vibration systems with conjugations using the non-classical method is a more general approach as compared to modelling and analysis in classical terms.

2

A note on the density of the strong product of graphs

80%

Pikies T.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

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2018

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tom T. 23

97--103

EN

This paper presents some lower and upper bounds on the density of a graph in its strong powers. They were created using the basic graph parameters and using basic properties of the strong product. The created bounds were sufficient to make a general conclusion about how the density in the strong powers of a graph behaves. On the basis of these considerations a simple conclusion follows on the merit of graph algorithms sensitive to the number of edges for applications to this type of graphs.

PL

Praca zawiera pewne dolne oraz górne ograniczenia dla gęstości silnych potęg grafu. Zostały one wyznaczone przy pomocy podstawowych parametrów grafu oraz podstawowych własności silnego produktu. Wyznaczone ograniczenia są wystarczające do wysnucia prostych wniosków odnośnie zachowanie gęstości w silnych potęgach grafu. Wnioski te świadczą o zasadności stosowania algorytmów wrażliwych na ilość krawędzi przy badaniu silnych potęg grafów.

3

Cyclability in bipartite graphs

80%

Amar D. , Flandrin E. , Gancarzewicz G.

Opuscula Mathematica

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2009

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tom Vol. 29, no. 4

345-364

EN

Let G = (X, Y; E) be a balanced 2-connected bipartite graph and S ⊂ V(G). We will say that S is cyclable in G if all vertices of S belong to a common cycle in G. We give sufficient degree conditions in a balanced bipartite graph G and a subset S ⊂ V(G) for the cyclability of the set S.

4

Locally Derivable Graphs

80%

Mazurkiewicz A.

Fundamenta Informaticae

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2007

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tom Vol. 75, nr 1-4

335-355

EN

In the paper a class of locally derivable graphs is defined and discussed. Well known particular cases of derivable graphs are (among others) trees, complete, and triangular graphs; in the paper a broader class of locally derivable graphs, called closed graphs, is defined. Nodes and edges of closed graphs can be partitioned into external and internal ones; the main property of such graphs their local reducibility: successive removing its external nodes leads eventually to a singleton, and removing its external edges leads to an a spanning tree of the graph. The class of closed graphs is then a class enabling structural reducing. This property can be applied in processor networks to design some local procedures leading to global results.

5

Connected domination polynomial of graphs

80%

Mojdeh D. A. , Emadi A. S.

Fasciculi Mathematici

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2018

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tom Nr 60

103--121

EN

Let G be a simple graph of order n. The connected domination polynomial of G is the polynomial Dc (G, x) = Σ |V(G)| i=γc(G) dc (G, i)xi, where dc (G, i) is the number of connected dominating sets of G of size i and γc (G) is the connected domination number of G. In this paper we study Dc (G, x) of any graph. We classify many families of graphs by studying their connected domination polynomial.

6

On computer-aided publication design

80%

Grelowska K. , Grabska E. , Łachwa A.

Machine Graphics and Vision

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2004

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tom Vol. 13, No. 1/2

167-179

EN

The article presents a method of computer aided publication design. We consider text as a structure of mark displayed on a certain background, without paying attention to its meaning. Our approach is illustrated by a computer program generating layouts of covers with help of graph grammars.

7

On minimal nonperfect graphs

80%

Balińska K. , Zwierzyński K.

Studia z Automatyki i Informatyki

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2008

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tom T. 33

7-12

EN

A simple graph is perfect if its chromatic number is equal to its clique number; otherwise a graph is called c-nonperfect with c ≥ 1 being the difference between these two invariants. The problem of defining the minimum number of vertices for c-nonperfect graphs as a function of the chromatic number is considered. The upper bound for this problem has been found by constructing sequences of c-nonperfect graphs with the use of Mycielski graphs and the join operation.

PL

Graf prosty jest doskonały, jeżeli jego liczba chromatyczna χ jest równa liczbie klikowej ω. Proponuje się podział grafów, dla których ten warunek nie jest spełniony, na klasy grafów c-niedoskonałych, gdzie c = χ−ω ≥ 1. Rozważa się następujący problem: określić minimalną liczbę nmin(c,χ) wierzchołków grafów c-niedoskonałych, które jednocześnie mają minimalną liczbę krawędzi. Podano regułę konstruowania ciągów grafów Rc(χ), których pierwszymi elementami są grafy Mycielskiego Mχ. Liczba wierzchołków grafów Rc(χ) stanowi górne ograniczenie wartości nmin(c,χ), które w przypadku c = 1 może być dokładne. Wykazano, że grafy R1(χ) i R2(χ) są minimalnie χ-chromatyczne.

8

Hiking Trails for Tourists in the "Chełmy" Landscape Park - Assessment of Their Route and Infrastructure Development

80%

Kołodziejczyk K.

Polish Journal of Sport and Tourism

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2011

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tom 18

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nr 4

324-329

EN

Introduction. The objective of the work was to assess the development of hiking trails for tourists and their infrastructure in the "Chełmy" Landscape Park in Lower Silesia. Material and methods. The analysis concerned a network of tourist trails whose coherence and shape were evaluated based on the indices derived from the graph theory. Also the correspondence between the names given to some trails with the tourist attractions accessible via such trails was assessed, and their number was compared to the length of the relevant trails. The analysis of the development of infrastructure for hiking tourists was conducted based on the results of local stocktaking and determination of tourist traffic density. Results. The obtained results show that the network of trails across the Park is quite well developed and coherent, despite the diversity of infrastructural development. The correspondence between the names of trails with their tourist attractions was confirmed with some reservations. Conclusions. Diverse trails in the studied area should be integrated into a coherent network by their similar development level, and in particular by introducing uniform marking standards. It would be also worth providing better access to some attractions for hiking tourists by introducing appropriate access routes.

9

Analiza możliwości poprawy własności transmisyjnych sieci dzięki zastosowaniu sterowania jej zasobami

80%

Drzycimski Z. , Bujnowski D.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2018

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tom nr 8-9

760--763, CD

PL

Niniejszy artykuł dotyczy możliwości poprawy własności transmisyjnych sieci telekomunikacyjnych opisanych grafami nieregularnymi, dzięki wykorzystaniu wyznaczonych współczynników nierównomierności do sterowania posiadanymi zasobami sieciowymi.

EN

These article concerns the possibility of improving the transmission properties of telecommunications networks described by irregular networks graphs, by use of designated unequal coefficients to control the network resources.

10

On LDPC codes corresponding to affine parts of generalized polygons

80%

Polak M. , Ustimenko V.

Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica

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2011

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tom Vol. 11, no. 2

143--152

EN

In this paper we describe how to use special induced subgraphs of generalized m-gons to obtain the LDPC error correcting codes. We compare the properties of codes related to the affine parts of q-regular generalised 6-gons with the properties of known LDPC codes corresponding to the graphs D(5, q).

11

Uwagi o właściwościach liczby zniewolenia dla grafów

80%

Guze S.

Prace Wydziału Nawigacyjnego Akademii Morskiej w Gdyni

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2006

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tom Z. 19

51-59

PL

W pracy zdefiniowano liczbę zniewolenia dla grafów. Następnie omówiono podstawowe właściwości, a w szczególności dokładne wartości liczby zniewolenia dla grafów pełnych, ścieżek, cykli oraz drzew. Przedstawione zostały także oszacowania górne i dolne dla tej liczby. Na zakończenie podano przykłady wyznaczania liczby zniewolenia w dowolnych grafach.

EN

The definition of the bondage number for graphs was introduced. Further, its elementary properties in particular the exact values of the bondage number for complete graphs, paths, cycles and trees were presented. The upper and lower bounds for this number were given as well. Finally, examples of determinig the bondage numbers in optional graphs were presented.

12

Graph quasi-continuity

80%

Mikucka A.

Demonstratio Mathematica

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2003

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tom Vol. 36, nr 2

483--494

13

Assembling the SARS-CoV genome - new method based on graph theoretical approach.

80%

Błażewicz J. , Figlerowicz M. , Formanowicz P. , Kasprzak M. , Nowierski B. , Styszyński R. , Szajkowski Ł. , Widera P. , Wiktorczyk M.

Acta Biochimica Polonica

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2004

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tom 51

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nr 4

983-993

EN

Nowadays, scientists may learn a lot about the organisms studied just by analyzing their genetic material. This requires the development of methods of reading genomes with high accuracy. It has become clear that the knowledge of the changes occuring within a viral genome is indispensable for effective fighting of the pathogen. A good example is SARS-CoV, which was a cause of death of many people and frightened the entire world with its fast and hard to prevent propagation. Rapid development of sequencing methods, like shotgun sequencing or sequencing by hybridization (SBH), gives scientists a good tool for reading genomes. However, since sequencing methods can read fragments of up to 1000 bp only, methods for sequence assembling are required in order to read whole genomes. In this paper a new assembling method, based on graph theoretical approach, is presented. The method was tested on SARS-CoV and the results were compared to the outcome of other widely known methods.

14

On the path partition of graphs

80%

Kouider M. , Zamime M.

Opuscula Mathematica

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2023

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tom Vol. 43, no. 6

829--839

EN

Let G be a graph of order n. The maximum and minimum degree of G are denoted by Δ and δ, respectively. The path partition number μ(G) of a graph G is the minimum number of paths needed to partition the vertices of G. Magnant, Wang and Yuan conjectured that [formula]. In this work, we give a positive answer to this conjecture, for Δ ≥ 2δ.

15

The supply of formal notions to synthesis of the vibrating discrete-continuous mechatronic systems

80%

Buchacz A.

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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tom Vol. 44, nr 2

168--178

EN

Purpose of this paper is modeling by different category graphs and analysis of vibrating clamped - free mechatronic system by the approximate method called Galerkin’s method. Such approach considers the frequency - modal analysis and assignment of amplitude - frequence charcteristics of the mechatronic system. Design/methodology/approach: was to nominate the relevance or irrelevance between the characteristics obtained by exact - only for shaft - and considered method. Such formulation especially concerns the relevance the relevance of the natural frequencies-poles of characteristics both of mechanical subsystem and the discrete - continuous clamped - free vibrating mechatronic system. Finding this approach is a fact, that approximate solutions fulfill all conditions for vibrating mechanical and/ or mechatronic systems and can be an introduction to synthesis of these systems modeled by different category graphs. Research limitations/implications: Research limitation is that both torsional vibrating continuous mechanical subsystem and mechatronic discrete - continuous subsystems are linear discrete - continuous are linear systems. Practical implications: of this study is that the main point can be the introduction to synthesis of considered class mechatronic bar-systems with constant changeable cross-section. Originality/valut Originality of such formulation rely on the use of the hypergraph methods of modelling and synthesis of torsionally vibrating bars to the synthesis of discrete-continuous mechatronic systems.

16

On a topological presentation of graphs

80%

Korczyński W.

Demonstratio Mathematica

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2004

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tom Vol. 37, nr 4

761--772

EN

In the paper a bitopological presentation of graphs has been described.

17

Grafy a teoria stabilnych alokacji

80%

Kozioł-Kaczorek D. , Pietrych Ł.

Econometrics. Ekonometria. Advances in Applied Data Analytics

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2016

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nr 3 (53)

102-114

EN

The paper discusses a model of matching process which was proposed by two American mathematicians: David Gale and Lloyd S. Shapley. The basic concept defined by them was the stable allocation, which can be achieved with so-called deferred acceptance algorithm. The article analyzes the problems discussed by the theory of stable allocations on the basis of graph theory. It has been shown that the issues raised by this theory can be ana-lyzed using bipartite graphs and networks weighted. They also formulated conditions which should be met in purpose to solve a problem of matching. References relate to the labor market, as a discussed issue is applicable in practice, especially in the design of systems of recruitment companies. The aim of the article is to present the problem of bilateral associa-tions with the use of the language of graph theory and an indication of possible applications in the area of search and match of job seekers and employers.

18

Long cycles and neighborhood union in 1-tough graphs with large degree sums

80%

Hoa V.

Discussiones Mathematicae Graph Theory

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1998

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tom 18

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nr 1

5-13

EN

For a 1-tough graph G we define σ₃(G) = min{d(u) + d(v) + d(w):{u,v,w} is an independent set of vertices} and $NC_{σ₃-n+5}(G)$ = $max{⋃_{i = 1}^{σ₃-n+5}$ $N(v_i) : {v₁, ..., v_{σ₃-n+5}}$ is an independent set of vertices}. We show that every 1-tough graph with σ₃(G) ≥ n contains a cycle of length at least $min{n,2NC_{σ₃-n+5}(G)+2}$. This result implies some well-known results of Faßbender [2] and of Flandrin, Jung & Li [6]. The main result of this paper also implies that c(G) ≥ min{n,2NC₂(G)+2} where NC₂(G) = min{|N(u) ∪ N(v)|:d(u,v) = 2}. This strengthens a result that c(G) ≥ min{n, 2NC₂(G)} of Bauer, Fan and Veldman [3].

19

Local dependency in networks

80%

Kudělka M. , Zehnalová Š. , Horák Z. , Krömer P. , Snášel V.

International Journal of Applied Mathematics and Computer Science

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2015

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tom 25

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nr 2

281-293

EN

Many real world data and processes have a network structure and can usefully be represented as graphs. Network analysis focuses on the relations among the nodes exploring the properties of each network. We introduce a method for measuring the strength of the relationship between two nodes of a network and for their ranking. This method is applicable to all kinds of networks, including directed and weighted networks. The approach extracts dependency relations among the network's nodes from the structure in local surroundings of individual nodes. For the tasks we deal with in this article, the key technical parameter is locality. Since only the surroundings of the examined nodes are used in computations, there is no need to analyze the entire network. This allows the application of our approach in the area of large-scale networks. We present several experiments using small networks as well as large-scale artificial and real world networks. The results of the experiments show high effectiveness due to the locality of our approach and also high quality node ranking comparable to PageRank.

20

Minimization of empty truck runs. Formulation of problem

70%

Ambroziak T. , Pawłowski D.

Research in Logistics & Production

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2019

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tom Vol. 9, No. 2

77--87

EN

The article formulates the issue of minimizing empty runs. Then, the interpretation of the issue of empty runs on numerical examples is presented. The formulation of the issue of minimizing empty runs requires the formulation of two optimization problems. The first one concerns distribution of commodities with minimal cost. The optimization problem formulated in this way is a well-known transport problem with the objective function being the costs of transport. The second one concerns commodity transport with distance minimization. After solving these two issues, the circulation problem of transport means is solved. Thanks to which we obtain the minimum number of empty runs expressed in distance units.