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Wyświetlanie 1-15 z 33
Tytuł:
Implementation of MUSCL-Hancock method into the C++ code for the Euler equations
Autorzy:
Murawski, K.
Stpiczyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/200996.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hyperbolic equations
numerical methods
Godunow methods
Opis:
In this paper we present implementation of the MUSCL-Hancock method for numerical solutions of the Euler equations. As a result of the internal complexity of these equations solving them numerically is a formidable task. With the use of the original C++ code, we developed and presented results of a numerical test that was performed. This test shows that our code copes very well with this task.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 1; 45-53
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Validation of the pressure wave model in the aspect of special structures endurance
Autorzy:
Barnat, W.
Powiązania:
https://bibliotekanauki.pl/articles/202084.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
explosion
analytical methods
numerical methods
eksplozja
metody analityczne
metody numeryczne
Opis:
The article presents results of the research on the validation of impact wave in the aspect of special structures’ endurance. Impact waves have been examined according to numerical and analytical methods. In order to verify the results obtained, a workstation for experimental research had been prepared. Before conducting the experiment, approximate pressure value had been checked empirically. The pressure had been measured using sensors for free wave measurements. The topic of the paper is empirical examination of the phenomenon of explosion in the aspect of the free wave pressure. Due to a difficulty of the issue, it was necessary to conduct complex examination of the phenomenon for various charges. The paper examines cases of spherical charge explosions with a balanced mass of 1 kg TNT.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 3; 707-716
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical methods of solving equations of hydrodynamics from perspectives of the code FLASH
Autorzy:
Murawski, K.
Lee, D.
Powiązania:
https://bibliotekanauki.pl/articles/202336.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical methods for hyperbolic equations
finite volume method
Godunov-type methods
Opis:
In this paper we review numerical methods for hydrodynamic equations. Internal complexity make numerical solutions of these equations a formidable task. We present results of advanced numerical simulations for a complex system with a use of a publicly available code, FLASH. These results proof that the numerical methods cope very well with this task.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 1; 81-91
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical solutions of magnetohydrodynamic equations
Autorzy:
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/202271.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical methods for hyperbolic equations
finite volume method
Godunov-type methods
magnetohydrodynamics
Opis:
In this paper we review several mathematical aspects in numerical methods for magnetohydrodynamic equations. The intrinsic complexity and the requirements of the selenoidity condition make numerical solutions of these equations a formidable task. We present results of advanced numerical simulations for a complex system, which reveal that the numerical methods cope very well with this task.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 2; 219-226
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multicriteria analysis in planning roads – Part 2. Methodology for selecting the optimal variant of the road
Autorzy:
Żabicki, P.
Gardziejczyk, W.
Powiązania:
https://bibliotekanauki.pl/articles/200423.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
normalization
assessment methods
multicriteria analysis
Opis:
The article presents the methodology for selecting the optimal variant of the road on a regional level. The suggested methodology is based on a combination of criteria value normalization method and the variant assessment method. Based on survey studies conducted using the Delphi method, a starting list of criteria was designed and the significance of the individual groups of main criteria and sub-criteria was determined. The final assessments of the analysed variants are calculated based on the aggregation of the marks obtained for the normalization and assessment methods. The methodology can be divided into six stages: determining the variants for analysis, selecting the variant assessment criteria, creating the assessment matrix, normalizing criteria value, using the variant assessment method, variant ranking. The methodology was tested on the examples of planning a bypass of Mazury and Księżyno towns as a part of Regional Road 678 in Poland.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 2; 351-360
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Visual data analysis with computational intelligence methods
Autorzy:
Kruse, R.
Steinbrecher, M.
Powiązania:
https://bibliotekanauki.pl/articles/200693.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
visual data analysis
computational intelligence methods
Opis:
Visual data analysis is an appealing and increasing field of application. We present two related visual analysis approaches that allow for the visualization of graphical model parameters and time-dependent association rules. When the graphical model is defined over purely nominal attributes, its local structure can be interpreted as an association rule. Such association rules comprise one of the most prominent and wide-spread analysis techniques for pattern detection, however, there are only few visualization methods. We introduce an alternative visual representation that also incorporates time since patterns are likely to change over time when the underlying data was collected from real-world processes. We apply the technique to both an artificial and a complex real-life dataset and show that the combined automatic and visual approach gives more and faster insight into the data than a fully-automatic approach only. Thus, our proposed method is capable of reducing considerably the analysis time.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2010, 58, 3; 393-401
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Godunov-type methods for two-component magnetohydrodynamic equations
Autorzy:
Murawski, K.
Tanaka, T.
Powiązania:
https://bibliotekanauki.pl/articles/201296.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-component magnetohydrodynamic equations
Godunov-type methods
Opis:
This paper is concerned with a numerical solutions of two-component magnetohydrodynamic equations. While a hyperbolic system of wave equations admits a shock solution as a result of the selenoidality condition the MHD equations are not strictly hyperbolic. As a consequence of that these equations require special numerical treatment. An application of a resulting numerical code to a problem of solar wind interaction with the ionosphere of the planet Venus is presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 2; 343-348
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the influence of current frequency on the thermal field of the insulated busbar
Autorzy:
Gołębiowski, J.
Zaręba, M.
Powiązania:
https://bibliotekanauki.pl/articles/200976.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
frequency analysis
analytical methods
temperature field
insulated busbar
Opis:
The paper analysed the influence of current frequency on the thermal field of the insulated busbar. Its physical model consists of two hollow cylinders and a solid cylinder with different material properties. In turn, the mathematical model is a system of heat conduction equations with the appropriate set of the boundary, initial and continuity conditions. The problem was solved using the modified Green’s method. As a result, the following characteristics and parameters of the busbar were determined as a functions of frequency: heating curves, local time constants, steady-state current ratings, and stationary temperature profiles. The results were positively verified by finite element method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 1; 89-97
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of regularization algorithms used for image reconstruction in computed tomography
Autorzy:
Wysoczański, D.
Mroczka, J.
Polak, A. G.
Powiązania:
https://bibliotekanauki.pl/articles/201356.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
computed tomography
image reconstruction
algebraic approach
regularization methods
Opis:
Computed tomography is one of the most significant diagnostic techniques in medicine. This work is focused on hard-field imaging, where signals take a form of straight rays and the reconstructed image can be presented as a matrix with unknown pixels. Algebraic methods for direct computation of the image have not been used in practice because of the scale of the problem and numerical errors appearing in the solution. The aim of this work was to analyse the performance of direct algebraic algorithms for tomographic image reconstruction including regularisation mechanism such as: generalised regularisation, Tikhonov regularisation, Twomey regularisation and ridge regression (RR), as well as comparing the results with the filtered backprojection (FBP) as the reference method. The performed analyses demonstrated that the regularised algebraic methods are more accurate than the commonly used FBP, and RR appeared the most precise among them. Additionally it was shown that the invariant system matrix (inverted during calculations) can be easily determined by solving the forward problem. Finally, potential directions of further research have been pointed out.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 2; 467-474
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of corrections for the Polish time scale UTC(PL) using artificial neural networks
Autorzy:
Luzar, M.
Sobolewski, Ł.
Miczulski, W.
Korbicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/202125.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
neural network
prediction methods
national timescale
atomic clock
Opis:
In this paper, the effectiveness of using Artificial Neural Networks (ANNs) for predicting the corrections of the Polish time scale UTC(PL) (Universal Coordinated Time) is presented. In particular, prediction results for the different types of neural networks, i.e., the MLP (MultiLayer Perceprton), the RBF (Radial Basis Function) and the GMDH (Group Method of Data Handling) are shown. The main advantages and disadvantages of using such types of neural networks are discussed. The prediction of corrections is performed using two methods: the time series analysis method and the regression method. The input data were prepared suitable for the above mentioned methods, based on two time series, ts1 and ts2. The designation of prediction errors for specified days and the influence of data quantity for the prediction error are considered. The paper consists of five sections. After Introduction, in Sec. 2, the theoretical background for different types of neural networks is presented. Section 3 shows data preparation for the appropriate type of neural network. The experimental results are presented in Sec. 4. Finally, Sec. 5 concludes the paper.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 3; 589-594
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of control representations on efficiency of local nonholonomic motion planning
Autorzy:
Duleba, I.
Powiązania:
https://bibliotekanauki.pl/articles/202269.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
motion planning
nonholonomic systems
Lie-algebraic methods
controllability
optimization
Opis:
In this paper various control representations selected from a family of harmonic controls were examined for the task of locally optimal motion planning of nonholonomic systems. To avoid dependence of results either on a particular system or a current point in a state space, considerations were carried out in a sub-space of a formal Lie algebra associated with a family of controlled systems. Analytical and simulation results are presented for two inputs and three dimensional state space and some hints for higher dimensional state spaces were given. Results of the paper are important for designers of motion planning algorithms not only to preserve controllability of the systems but also to optimize their motion.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 2; 213-218
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized ordered linear regression with regularization
Autorzy:
Łęski, J.
Henzel, N.
Powiązania:
https://bibliotekanauki.pl/articles/201591.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
linear regression
IRLS
OWA
conjugate gradient optimization
robust methods
Opis:
Linear regression analysis has become a fundamental tool in experimental sciences. We propose a new method for parameter estimation in linear models. The 'Generalized Ordered Linear Regression with Regularization' (GOLRR) uses various loss functions (including the o-insensitive ones), ordered weighted averaging of the residuals, and regularization. The algorithm consists in solving a sequence of weighted quadratic minimization problems where the weights used for the next iteration depend not only on the values but also on the order of the model residuals obtained for the current iteration. Such regression problem may be transformed into the iterative reweighted least squares scenario. The conjugate gradient algorithm is used to minimize the proposed criterion function. Finally, numerical examples are given to demonstrate the validity of the method proposed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 3; 481-489
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microscopic methods for analysis of mortars from historical masonry structures
Autorzy:
Owsiak, Zdzisława
Powiązania:
https://bibliotekanauki.pl/articles/2090727.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
historical buildings
mortar
microscopic methods
budynki historyczne
metody mikroskopowe
zaprawa
Opis:
The process of historical building conservation includes the repair of mortars eroded due to material and environmental factors. Identification of old mortar constituents is necessary to enable duplicating the material. Information on the binder and aggregate types and contents can be obtained from microscopic observation used in combination with instrumental methods. This paper presents the results of microstructure and mineral composition tests of mortars collected from the walls of thirteenth century buildings. A combination of techniques was used, which included X-ray diffraction, transmitted light optical microscopy and scanning electron microscopy with micro-area elemental composition analysis. The test results revealed porous lime and sand mortars with a binder-aggregate ratio often beyond the commonly adopted values. The mortars contained sand grains of up to 0.5 mm and larger pieces of limestone, flint, feldspar and brick. Transmitted light optical microscopy and scanning microscopy were found to be essential techniques for mortar characterization in existing buildings and structures.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; e136042, 1--8
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ensemble of data mining methods for gene ranking
Autorzy:
Wiliński, A.
Osowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/201570.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gene expression array
feature selection
gene ranking methods
classification
SVM
Opis:
The paper presents the ensemble of data mining methods for discovering the most important genes and gene sequences generated by the gene expression arrays, responsible for the recognition of a particular type of cancer. The analyzed methods include the correlation of the feature with a class, application of the statistical hypotheses, the Fisher measure of discrimination and application of the linear Support Vector Machine for characterization of the discrimination ability of the features. In the first step of ranking we apply each method individually, choosing the genes most often selected in the cross validation of the available data set. In the next step we combine the results of different selection methods together and once again choose the genes most frequently appearing in the selected sets. On the basis of this we form the final ranking of the genes. The most important genes form the input information delivered to the Support Vector Machine (SVM) classifier, responsible for the final recognition of tumor from non-tumor data. Different forms of checking the correctness of the proposed ranking procedure have been applied. The first one is relied on mapping the distribution of selected genes on the two-coordinate system formed by two most important principal components of the PCA transformation and applying the cluster quality measures. The other one depicts the results in the graphical form by presenting the gene expressions in the form of pixel intensity for the available data. The final confirmation of the quality of the proposed ranking method are the classification results of recognition of the cancer cases from the non-cancer (normal) ones, performed using the Gaussian kernel SVM. The results of selection of the most significant genes used by the SVM for recognition of the prostate cancer cases from normal cases have confirmed a good accuracy of results. The presented methodology is of potential use for practical application in bioinformatics.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 3; 461-470
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microscopic methods for analysis of mortars from historical masonry structures
Autorzy:
Owsiak, Zdzisława
Powiązania:
https://bibliotekanauki.pl/articles/2173559.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
historical buildings
mortar
microscopic methods
budynki historyczne
metody mikroskopowe
zaprawa
Opis:
The process of historical building conservation includes the repair of mortars eroded due to material and environmental factors. Identification of old mortar constituents is necessary to enable duplicating the material. Information on the binder and aggregate types and contents can be obtained from microscopic observation used in combination with instrumental methods. This paper presents the results of microstructure and mineral composition tests of mortars collected from the walls of thirteenth century buildings. A combination of techniques was used, which included X-ray diffraction, transmitted light optical microscopy and scanning electron microscopy with micro-area elemental composition analysis. The test results revealed porous lime and sand mortars with a binder-aggregate ratio often beyond the commonly adopted values. The mortars contained sand grains of up to 0.5 mm and larger pieces of limestone, flint, feldspar and brick. Transmitted light optical microscopy and scanning microscopy were found to be essential techniques for mortar characterization in existing buildings and structures.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; art. no. e136042
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 33

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