Wyniki wyszukiwania - BazTech

1

Stability and bifurcation analysis for an airfoil model with a high-order nonlinear spring

Li Shuqun, Zhou Liangqiang

Journal of Theoretical and Applied Mechanics

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2022

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Vol. 60 nr 2

185--197

EN

In this paper, the stability and bifurcation of an airfoil model with a high-order nonlinear spring are investigated both analytically and numerically. Two possible types of bifurcation at the equilibrium point are studied. It is proved that the zero characteristic root can only be a single zero. With the help of the center manifold theory and the normal form theory, the expressions of critical bifurcation curves leading to initial bifurcation and secondary bifurcation are obtained. Numerical simulations confirm the theoretical results.

2

Analiza i eksploracja danych metodami syntezy logicznej

Łuba Tadeusz, Wąsicki Dariusz

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2020

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nr 1

3--11

PL

W artykule dyskutowane są możliwości zastosowania metod syntezy logicznej w zadaniach eksploracji danych. W szczególności omawiana jest metoda redukcji atrybutów oraz metoda indukcji reguł decyzyjnych. Pokazano, że metody syntezy logicznej skutecznie usprawniają te procedury i z powodzeniem mogą być zastosowane do rozwiązywania ogólniejszych zadań eksploracji danych. W uzasadnieniu celowości takiego postępowania omówiono diagnozowanie pacjentów z możliwością eliminowania kłopotliwych badań.

EN

The article discusses the possibilities of application of logic synthesis methods in data mining tasks. In particular, the method of reducing attributes and the method of inducing decision rules is considered. It is shown that by applying specialized logic synthesis methods, these issues can be effectively improved and successfully used for solving data mining tasks. In justification of the advisability of such proceedings, the patient's diagnosis with the possibility of eliminating troublesome tests is discussed.

3

Asymptotic behavior of small solutions of the Benjamin–Ono equation with time-dependent coefficients

Mammeri Y.

Journal of Applied Analysis

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2015

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Vol. 21, nr 1

9--23

EN

We study the behavior of small solutions depending on time of the generalized and regularized Benjamin–Ono equation in both continuous and periodic context. In particular, we prove that these solutions remain small for a time scale improving the natural time given by the localwell-posedness. In the continuous case, the result becomes global-in-time.

4

The role of normal logical form in decision - making and knowledge management

Galanc T., Kołwzan W., Pieronek J.

Operations Research and Decisions

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2014

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Vol. 24, No. 2

35--58

EN

The normal form in logic has been considered. Any propositional function, i.e. any finite logical expression can be written in such a form. This indicates the possibility of an unequivocal logical representation of many different objects investigated in science and everyday life. The properties of the normal form give a new dimension to the management of processes examined in science. Understanding of the laws of logic and its calculus allows us to obtain this form in a finite number of logical transformations. In addition, this form indicates the cognitive essence and pragmatic dimension of logic. The paper considers axiomatization, and then optimization. Both of these formulations of logic reflect its essence. Shannon’s theorem gives us only a modest signpost that reality has a complex nature, which is confirmed by the richness of logic in the form of its equivalent propositional functions. Knowledge about the behavior of these structures is ambiguous in terms of the complexity of the corresponding logical expressions, that is, two different or identical logical functions may be related to identical (similar) or quite different behaviors in relation to the processes or objects represented by these functions.

5

Handling equivalence classes of Optimality-Theoretic comparative tableaux

Yanovich I.

Journal of Language Modelling

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2014

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Vol. 2, No. 2

285--306

EN

Many Optimality-Theoretic tableaux contain exactly the same information, and equivalence-preserving operations on them have been an object of study for some two decades. This paper shows that several of the operations proposed in the earlier literature together are actually enough to express any possible equivalence-preserving transformation. Moreover, every equivalence class of comparative tableaux (equivalently, of sets of Elementary Ranking Conditions, or ERC sets) has a unique and computable normal form that can be derived using those elementary operations in polynomial time. Any equivalence-preserving operation on comparative tableaux (ERC sets) is thus computable, and normal form tableaux may therefore represent their equivalence classes without loss of generality. Optimality Theory (OT) is a grammatical formalism based on constraint competition, formulated by Prince and Smolensky (1993) (later published as Prince and Smolensky (2004)). OT is especially popular in phonology, and is used to some extent in other branches of linguistics. In OT, a set of competing output forms {Output₁, Output₂,…} is generated by machine Gen for the underlying form Input. Each pair N is then evaluated against a set of constraints Con. The grammar of a particular language is modeled as an ordering of the universal set of constraints Con which determines the winning input-output pair for each Input: an input-output pair α = N wins over another pair β = M when α incurs fewer violations than β in the most highly ranked constraint where α and β differ. The input-output pairs that do not lose to any other pair are declared grammatical. The OT formalism expresses two important intuitions regarding how languages might function. First, it easily captures conditions of the form “try A; if impossible, try B; if also impossible, resort to C”, which seem to frequently occur in natural language. Second, OT allows for elegant modeling of cross-linguistic variation and language change in terms of re-ranking of a universal set of constraints. The information that a given dataset contributes constrains the possible rankings of constraints. Such information may be represented in the form of a comparative tableau (Prince 2000) or the corresponding set of Elementary Ranking Conditions, or ERC set (Prince 2002). In this paper, I present an incremental step completing the development of a full theory of equivalence classes of comparative OT tableaux, or, equivalently, ERC sets. Earlier work, especially that of Hayes (1997), Prince (2000), Prince (2002), Brasoveanu and Prince (2011)¹, and Prince (2006), has established a number of results concerning how one may transform the information in an OT tableau without loss. What has not yet been done in this line of research is to establish the limits of operations that preserve equivalence. For example, the following natural question has not been answered: given two arbitrary comparative tableaux or ERC sets, can we determine whether they contain identical information?² The present paper fills this gap: I show that any (finite) comparative tableau may be (computably, and actually quite efficiently) transformed into a normal form, which is unique for the whole equivalence class. Moreover, this transformation is possible by applying a sequence of a set of five elementary operations and their inverses already introduced in the literature. Only two of those are non-trivial, so a very small and simple set turns out to be sufficient to capture all the diversity of possible equivalence-preserving operations on tableaux. Normalization gives us a handle on equivalence classes of tableaux/ERC sets, as we show that each equivalence class contains exactly one normal form tableau. The normal form may therefore serve as the class’s representative. A test for equivalence of arbitrary tableaux (computable for finite tableaux) involves normalizing the input tableaux and comparing the resulting normal form tableaux. The original tableaux are equivalent if and only if their normal forms are identical. Thanks to the normal form theorem proved in the present paper, the space of all possible equivalence-preserving operations may be enumerated, and the same is true of the members of which equivalence class.

6

Wydajność złączeń i zagnieżdżeń dla schematów znormalizowanych i zdenormalizowanych

Jajeśnica Ł., Piórkowski A.

Studia Informatica

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2010

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Vol. 31, nr 2A

445-456

PL

Niniejszy artykuł stanowi rozważania na temat wydajnościowych aspektów normalizacji schematów baz danych. Przedstawiono ideę konstrukcji dużych baz danych i hurtowni w postaciach znormalizowanej (schemat płatka śniegu) i zdenormalizowanej (schemat gwiazdy). Jako przykład wybrano wymiar czasu geologicznego, nieodzownego w konstrukcji baz danych geologicznych. Wymiar ten tworzy hierarchię jednostek geochronologicznych. Przeprowadzono eksperymenty sprawdzające wydajność dla złączeń i zagnieżdżeń skorelowanych dla systemów zarządzania bazami danych MySQL i PostgreSQL.

EN

This article provides a reflection on the performance aspects of database normalization schemas. It resents the idea of the construction of large databases and warehouses on standardized forms (snowflake schema) and denormalized (star schema). Dimension was chosen as an example of geological time, indispensable in the construction of geological database. This dimension creates a hierarchy of chronostratigraphy units. Experiments were carried out to check the performance of the joints and nesting correlated to the database management system MySQL and PostgreSQL.