Autor: Bołtuć, A. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: "PIES" in problems of 2D elasticity with body forces on polygonal domains
PURC w dwuwymiarowych problemach teorii sprężystości z siłami masowymi na wielokątnych obszarach
Autorzy:: Bołtuć, A.
Zieniuk, E.
Powiązania:: https://bibliotekanauki.pl/articles/281042.pdf
Data publikacji:: 2011
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: parametric integral equation system (PIES)
elasticity
body forces
Bezier surfaces
Opis:: The paper presents a thorough review of the effective approach to solving problems of plane elasticity with body forces of different types. The proposed method bases on generalization of the parametric integral equation system (PIES), which was successfully applied to solving boundary problems without body forces. The main aim of the mentioned generalization was to create such an approach which does not require physical discretization of the domain, or division it into cells, like it is done in the classic boundary element method (BEM). First, only problems defined on polygons were considered. The paper also contains the analysis of the accuracy of obtained solutions in comparison with analytical or other numerical results.
W pracy zaprezentowano i gruntownie zweryfikowano efektywny sposób rozwiązywania zagadnień z zakresu płaskiej teorii sprężystości z siłami masowymi różnego typu. Zaproponowany sposób polega na uogólnieniu parametrycznego układu równań całkowych (PURC), wcześniej z sukcesem stosowanego do rozwiązywania zagadnień brzegowych bez sił masowych. Celem uogólnienia było zastosowane takiego podejścia, które charakteryzowałoby się brakiem konieczności fizycznej dyskretyzacji obszaru czy dzielenia go na komórki, jak jest to stosowane w klasycznej metodzie elementów brzegowych (MEB). W pracy w pierwszej kolejności ograniczono się do zagadnień zdefiniowanych na obszarach wielokątnych. W pracy dokonano analizy dokładności otrzymywanych rozwiązań w porównaniu do wyników analitycznych oraz numerycznych.
Źródło:: Journal of Theoretical and Applied Mechanics; 2011, 49, 2; 369-384
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A non-element method of solving the two-dimensional Navier-Lamé equation in problems with non-homogeneous polygonal subregions
Autorzy:: Zieniuk, E.
Bołtuć, A.
Powiązania:: https://bibliotekanauki.pl/articles/1933185.pdf
Data publikacji:: 2008
Wydawca:: Politechnika Gdańska
Tematy:: Navier-Lamé equation
boundary problems
subregions
PIES
Opis:: The paper introduces a parametric integral equation system (PIES) for solving 2D boundary problems defined on connected polygonal domains described by the Navier-Lame equation. Parametric linear functions were applied in the PIES to define analytically the polygonal subregions' interfaces. Only corner points and additional extreme points on the interface between the connected subregions are posed to practically define a polygonal domain. An important advantage of this approach is that the number of such points is independent of the area of identically shaped domains due to the elimination of traditional elements from modeling, the number of those elements being dependent on the domain's surface area. In order to test the reliability and effectiveness of the proposed method, test examples are included in which areas of displacements and stresses are analyzed in each subregion.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 1-2; 71-84
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Identification of polygonal domains using PIES in inverse boundary problems modeled by 2D Laplaces equation
Autorzy:: Zieniuk, E.
Bołtuć, A.
Powiązania:: https://bibliotekanauki.pl/articles/1964153.pdf
Data publikacji:: 2005
Wydawca:: Politechnika Gdańska
Tematy:: parametric integral equation system (PIES)
inverse problems
Laplace's equation
Opis:: The paper presents an original method to identify polygonal boundary geometry in 2D boundary problems defined by Laplace's equation using a parametric integral equation system (PIES). In the PIES, the polygonal boundary shape is defined mathematically by means of parametric linear segments, with a small number of corner points being posed. Identification of the polygonal boundary is reduced to identification of the corner points. Finally, the solution of the problem is reduced to the solution of a non-linear system of algebraic equations. Coordinates of identified corner points are obtained after solving the system of equations.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 4; 415-426
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Application of PIES and rectangular Bezier surfaces to complex and non-homogeneous problems of elasticity with body forces
Autorzy:: Boltuc, A.
Zieniuk, E.
Powiązania:: https://bibliotekanauki.pl/articles/1955310.pdf
Data publikacji:: 2010
Wydawca:: Politechnika Gdańska
Tematy:: boundary problems
elasticity
body forces
non-homogeneous materials
Bezier surfaces
parametric integral equation system (PIES)
Opis:: This paper presents a variety of applications of an effective way to solve boundary value problems of 2D elasticity with body forces. An overview of the approach is presented, its numerical implementation, as well as a number of applications, ranging from problems defined on elementary shapes to complex problems, e.g. with non-homogeneous material. The results obtained by the parametric integral equation system (PIES) were compared with the analytical and numerical solutions obtained by other computer methods, confirming the effectiveness of the method and its applicability to a variety of problems.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 4; 363-376
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Shape identification in nonlinear boundary problems solved by pies method
Autorzy:: Zieniuk, E.
Bołtuć, A.
Szerszeń, K.
Powiązania:: https://bibliotekanauki.pl/articles/387431.pdf
Data publikacji:: 2014
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:: PIES
PIES method
defect
shape identification
nonlinear equation
metoda PIES
defekt
identyfikacja kształtu
równanie nieliniowe
Opis:: The paper presents the strategy for identifying the shape of defects in the domain defined in the boundary value problem modelled by the nonlinear differential equation. To solve the nonlinear problem in the iterative process the PIES method and its ad-vantages were used: the efficient way of the boundary and the domain modelling and global integration. The identification was performed using the genetic algorithm, where in connection with the efficiency of PIES we identify the small number of data required to the defect’s definition. The strategy has been tested for different shapes of defects.
Źródło:: Acta Mechanica et Automatica; 2014, 8, 1; 16-21
1898-4088
2300-5319
Pojawia się w:: Acta Mechanica et Automatica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Prevalence of neoplasms in patients with acromegaly – the need for a national registry
Autorzy:: Matyjaszek-Matuszek, B.
Obel, E.
Lewicki, M.
Kowalczyk-Bołtuć, J.
Smoleń, A.
Powiązania:: https://bibliotekanauki.pl/articles/2081765.pdf
Data publikacji:: 2018
Wydawca:: Instytut Medycyny Wsi
Tematy:: cancer
acromegaly
registry
IGF-1
GH
neoplasms
Opis:: Introduction. Acromegaly is an endocrine disorder caused predominantly by pituitary adenoma leading to autonomic oversecretion of growth hormone and secondary elevation of insulin-like growth factor 1 (IGF-1). Consequently, there are both theoretical and experimental grounds for establishing a correlation between this disorder and the higher incidence of neoplasms. Objective. The aim of the study is to evaluate the incidence and types of neoplasms among patients with acromegaly. Materials and method. The study included 67 patients with acromegaly, aged between 24 and 75±18.8 years, 46 women (68.7%) and 21 men (31.3%), BMI: 30.7±5.7 kg/m2, age at diagnosis 49.1±12.5 years, with the medians of GH and IGF-1 levels at diagnosis of 11.3 ng/ml and 663.8 ng/ml, respectively. A retrospective analysis of medical records with particular regard to physical examination, medical history, laboratory and imaging tests was performed. Results. Fifty-one patients (76.1%) suffered from at least one neoplasm, among whom 48 patients (71.6%) had benign proliferations, whereas malignant neoplasms (larynx, endometrial and colon cancers) were found in only three patients (4.5%). Conclusions. Benign neoplasms were found in majority of patients with acromegaly (71.6%) most notably: nodular goiter and colon polyps; malignant lesions were rare (4.5%). Only every fifth patient suffered from no neoplastic proliferations. No correlations between the studied parameters and the incidence of neoplasms were found, most likely due to the small number of patients. This is the reason for proposing the creating of the first national register of incidences of neoplasms among acromegalic patients.
Źródło:: Annals of Agricultural and Environmental Medicine; 2018, 25, 3; 559-561
1232-1966
Pojawia się w:: Annals of Agricultural and Environmental Medicine
Dostawca treści:: Biblioteka Nauki