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Wyświetlanie 1-15 z 70
Tytuł:
The Cartan-Monge geometric approach to the generalized characteristics method and its application to the heat equation Ut - Uxx = 0
Autorzy:
Golenia, J.
Prykarpatsky, Y. A.
Wachnicki, E.
Powiązania:
https://bibliotekanauki.pl/articles/255525.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
characteristics method
heat equation
Opis:
The generalized Cartan-Monge type approach to the characteristics method is discussed from the geometric point of view. Its application to the classical one-dimensional linear heat equation Ut - uxx = 0 is presented. It is shown that the corresponding exact solution of the Cauchy problem can be represented in a classical functional-analytic Gauss type form.
Źródło:
Opuscula Mathematica; 2009, 29, 1; 27-39
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of characteristics for design of centrifugal pump geometry
Autorzy:
Puzyrewski, R.
Zochowski, K.
Flaszyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/1943212.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska
Tematy:
pumps
inverse problem
method of characteristics
Opis:
The method of characteristics leads to the blade geometry of a centrifugal pump. The method is built taking the advantage of the governing equations of fluid mechanics written in a non-orthogonal coordinates system. The coordinate system is based on an analytically described boundary of a centrifugal pump. Some of the information concerning the designed geometry should be introduced in advance. The mass conservation equation needs the information of the blockage factor resulting from the blading thickness. In the momentum conservation equation the body force replaces the blading force together with the friction force. In the energy conservation equation the dissipation effects are represented by a loss coefficient. It is shown that while simplifying the body force vector, the set of equations reduces to a hyperbolic system which allows applying the method of characteristics. The shapes of surfaces representing the designed blading can be built from the trajectories of fluid particles.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 3; 249-256
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation and discretization of random field in the slip-line method
Autorzy:
Przewłócki, J.
Powiązania:
https://bibliotekanauki.pl/articles/240960.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
bearing capacity
method of characteristics
random field
Opis:
The paper deals with the problem of bearing capacity of a strip footing based on the random subsoil. The solution has been obtained in a framework of the slip-line method. In order to include randomness of the soil medium, a modification of the method of characteristics is proposed. In such an approach, the stochastic finite difference method based on the Monte Carlo technique has been adopted. It enables including a spatial variability of soil properties into the analysis and to determine its influence on the variance of the ultimate collapse load. It is assumed that the soil medium is purely cohesive and only its cohesion can be considered as a random field. The simulation algorithm of multi-dimensional random field, based on the diagonalisation of the covariance matrix by a transformation using a lower-triangle matrix is described. The problems of the medium discretization and stabilization of the solution are discussed.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2003, 50, 4; 343-358
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sufficient conditions for optimality for a mathematical model of drug treatment with pharmacodynamics
Autorzy:
Leszczynski, M.
Ratajczyk, E.
Ledzewicz, U.
Schättler, H.
Powiązania:
https://bibliotekanauki.pl/articles/255130.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
optimal control
sufficient conditions for optimality
method of characteristics
pharmacodynamic model
Opis:
We consider an optimal control problem for a general mathematical model of drug treatment with a single agent. The control represents the concentration of the agent and its effect (pharmacodynamics) is modelled by a Hill function (i.e., Michaelis-Menten type kinetics). The aim is to minimize a cost functional consisting of a weighted average related to the state of the system (both at the end and during a fixed therapy horizon) and to the total amount of drugs given. The latter is an indirect measure for the side effects of treatment. It is shown that optimal controls are continuous functions of time that change between full or no dose segments with connecting pieces that take values in the interior of the control set. Sufficient conditions for the strong local optimality of an extremal controlled trajectory in terms of the existence of a solution to a piecewise defined Riccati differential equation are given.
Źródło:
Opuscula Mathematica; 2017, 37, 3; 403-419
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A numerical approach to the standard model of water hammer with fluid-structure interaction
Autorzy:
Henclik, S.
Powiązania:
https://bibliotekanauki.pl/articles/281051.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
water hammer
transient pipe flow
fluid-structure interaction
standard model
method of characteristics
Opis:
In the classic water hammer (WH) theory, 1D liquid flow in a quasi-rigid pipe is assumed. When the pipe is flexible or is fixed to the foundation with elastic supports, the dynamic fluid structure interaction (FSI) should be taken into account for more accurate modelling of the system behaviour. The standard model of WH-FSI for a straight pipe reach is governed by fourteen hyperbolic partial differential equations of the first order, two for 1D liquid flow and twelve for 3D motion of the pipe. This model is presented in the paper and an algorithm for its numerical solution based of the method of characteristics is proposed. Basic boundary conditions (BC) are shortly discussed. The important condition at the junction of two subpipes fixed to the foundation with a viscoelastic support is presented in details and a general method of its solution is proposed.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 543-555
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical model and numerical computations of transient pipe flows with fluid-structure interaction
Autorzy:
Henclik, S.
Powiązania:
https://bibliotekanauki.pl/articles/175378.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
waterhammer
transient pipe flow
fluid-structure interaction (FSI)
numerical modeling
method of characteristics
Opis:
Transient flows in closed conduits are of interest from over a century, but the dynamic interaction between the fluid and the pipe is taken into consideration more thoroughly just from a few decades. A standard model of the phenomenon consists of fourteen first order partial differential equations (PDE), two for a one-dimensional (1D) liquid flow and twelve for 3D pipe motion. In many practical cases however, a simpler four equations (4E) model can be used, where 1D longitudinal pipe movement is assumed. A short description of waterhammer event with fluidstructure interaction taken into account is presented in the article. The 4E mathematical model is presented in detail with the assumptions and main algorithms of computer program that has been developed. Two phase flow is assumed not to take place, but the friction between the liquid and the pipe wall are taken into consideration. A method of characteristics (MOC) with time marching procedure is employed for finding the solutions, but instead of direct solving the resulting finite difference equations (FDE) the “wave method” is proposed. Some other important elements of the algorithm are presented and selected results of numerical computations as well.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2010, 122; 77-94
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A boundary condotions at modeling 1-D pulsating flows in pipes according to the method of characteristics
Autorzy:
Pałczyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/246623.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
1D simulations
Valve boundary conditions
method of characteristics
pulsating flow at pipes
Opis:
At this paper, there were compared three conceptions of boundary conditions and their definition at partially opened pipes. This is typical at inlet and exhaust pipes of internal combustion engines and piston compressors. At an introduction there were listed the current state of affairs at a one dimensional modelling pulsations according to the Method of Characteristics (MOC). Subsequently, there was presented the main idea of MOC. At the third chapter there were presented general guidelines at initial and boundary conditions definition. Next there are three descriptions of the analyzed problem. Firstly, there was presented partially open end phenomena at space and stage plane. Secondly, there was shown the theory of acoustic wave propagation with description of stage waves at analyzed ends of pipe. Lastly, there is a new conception of constant pressure valve boundary conditions, which is the synthesis of the both mentioned earlier. At the fourth paragraph there was shortly presented existing test rig dedicated to research of pulsating flow in pipes. This test rig was built at Flow Metrology Division of Lodz University of Technology [9]. At the second part of this chapter there were shown main assumption of elaborated simulation algorithm at Matlab Simulink environment. Lastly there were discussed simulation results compared with presented conceptions of boundary conditions.
Źródło:
Journal of KONES; 2012, 19, 2; 395-402
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydraulic transients analysis in pipe networks by the method of characteristics (MOC)
Autorzy:
Wichowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/240954.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
hydraulic transients
method of characteristics
single pipe
experimental measurement
pipe networks
numerical simulations
Opis:
The paper presents results of an experimental and theoretical study of the hydraulic transients in straight pipes and numerical simulations of unsteady flow in pipe networks. A mathematical model consists of a set of partial differential equations of hyperbolic type, which have been transformed by the method of characteristics into ordinary differential equations which are solved by the predictor-corrector method. Experimental tests have been performed, in order to examine the hydraulic transients phenomenon, in a single straight steel pipe. The experiments were carried out in the hydraulic laboratory of the Institute of Water Supply and Water Engineering, Environmental Engineering Faculty, Warsaw University of Technology. The numerical results show that the presented one dimensional model for a single pipe correctly describes the phenomenon since there is a good agreement with experimental maximum and minimum oscillations. In the paper, selected exemplary equations in a difference form for the pipe networks are also presented. One calculation example is given relating to the complex water-pipe network consisting of 17 loops, 48 pipelines and 33 nodes, supplied by two independent sources. Water-hammer throughout the whole pipeline network was caused by closing the gate valve at mid-point of one selected pipe. The results of the numerical calculations are presented in graphic form with respect to the final cross-sections of pipes.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2006, 53, 3; 267-291
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parameters affecting water hammer in plastic pipelines
Autorzy:
Urbanowicz, K.
Firkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/135271.pdf
Data publikacji:
2018
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
water hammer
unsteady flow
viscoelastic pipes
method of characteristics
partial differential equations
creep function
Opis:
Pressure pipes made of selected plastics are widely used in current water supply systems. Unfortunately, the theoretical basis for modeling transient flows in these pipes has not been clarified yet. For simplified one-dimensional numerical modeling, a model is commonly used in which the total deformation of the pipe walls is expressed by the sum of instantaneous and retarded deformations. One of the main problems lies in the correct experimental determination of the creep function defining the properties of the polymer. The influence of other parameters on which the numerical solution of the method of characteristics is based is the subject of the research presented in this paper.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2018, 54 (126); 35-43
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Task Characteristics on Mastery/Non-mastery Decisions
Wpływ właściwości zadania testowego na decyzje klasyfikacyjne
Autorzy:
Malec, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/1945215.pdf
Data publikacji:
2008
Wydawca:
Katolicki Uniwersytet Lubelski Jana Pawła II. Towarzystwo Naukowe KUL
Tematy:
pomiar sprawdzający
efekt metody
aspekty metody testowania
forma zadania
decyzje klasyfikacyjne
testowanie kolokacji
criterion-referenced measurement
method effect
task characteristics (test method facets)
item format
classification decisions
collocation testing
Opis:
Artykuł jest opisem badania, którego celem było udzielenie odpowiedzi na pytanie, czy właściwości zadania testowego mają wpływ na decyzje klasyfikacyjne w kontekście pomiaru sprawdzającego. Zastosowane narzędzia pomiaru, które sprawdzały znajomość kolokacji (łączliwości wyrazów) języka angielskiego, składały się zarówno z zadań zamkniętych, jak i otwartych różnego typu. Wszystkie testy kolokacji charakteryzowały się wysokim poziomem rzetelności decyzji klasyfikacyjnych oraz trafnością teoretyczną. Analiza wariancji z powtarzanym pomiarem wykazała istotność efektu metody testowania, polegającego na tym, że osiągnięcie przez studenta progu zaliczeniowego zależy od zastosowanej formy zadania testowego.
Źródło:
Roczniki Humanistyczne; 2008, 56, 5; 93-113
0035-7707
Pojawia się w:
Roczniki Humanistyczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of linear parametric circuits in the frequency domain
Autorzy:
Shapovalov, Yu.
Mandziy, B.
Bachyk, D.
Powiązania:
https://bibliotekanauki.pl/articles/410827.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
symbolic frequency method
objective function
function – characteristics
Opis:
The possibility of application of the frequency symbolic method of analysis of linear parametric circuits to the decision of optimization tasks is considered. There are examples of optimization of single- and doublecircuit parametric amplifier using the objective function based on the calculation of parametric transfer function of a circuit with a symbolic representation of the parameters of the parametric capacity. By the frequency symbolic method the parametric transfer functions are approximated by trigonometric polynomials of Fourier.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2013, 2, 4; 73-77
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method for calculating performance characteristics of hydrokinetic turbines
Autorzy:
Góralczyk, A.
Chaja, P.
Adamkowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1934038.pdf
Data publikacji:
2011
Wydawca:
Politechnika Gdańska
Tematy:
hydrokinetic turbines
Vortex-Lattice Method
performance characteristics
Opis:
This paper presents a numerical algorithm and its computer implementation (program) developed to determine the operational characteristics of axial flow hydrokinetic turbines. The program is based on the Vortex-Lattice Method (VLM), which proved useful for predicting hydrodynamic characteristics of screw propellers. In order to validate the software, we carried out a series of experiments on a laboratory test stand at the Institute of Fluid-Flow Machinery at the Polish Academy of Sciences (IMP PAN) in Gdansk. From the practical point of view, the agreement between the calculated and experimental results was satisfactory. Therefore, the developed numerical method can be a useful tool for the analysis of operating conditions and in the design of hydrokinetic turbines.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2011, 15, 1; 43-57
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Chaplyghin method for first order partial differential equations
Autorzy:
Puźniakowska, E.
Powiązania:
https://bibliotekanauki.pl/articles/255777.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
characteristics
Newton method
Chaplyghin sequences
initial problems
Opis:
Classical solutions of initial problems for nonlinear first order partial differential equations are considered. It is shown that under natural assumptions on given functions, there exist Chaplyghin sequences and they are convergent. Error estimates for approximate solutions are given. The method of characteristics is used for the construction of approximate solutions.
Źródło:
Opuscula Mathematica; 2008, 28, 2; 163-178
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The comparison of uniformity decisions based on COYU and Bennett’s methods - oilseed rape data
Rzepak ozimy - porównanie decyzji dotyczących wyrównania odmian przy użyciu metody COYU i metody Bennetta
Autorzy:
Zawieja, B.
Pilarczyk, W.
Kowalczyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/9635.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Katedra Zastosowań Matematyki i Informatyki
Tematy:
uniformity
plant variation
quantitative characteristics
COYU method
Bennett method
oilseed rape
Źródło:
Colloquium Biometricum; 2009, 39
1896-7701
Pojawia się w:
Colloquium Biometricum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of a nonlinear tuned mass damper by using the multi-scale method
Autorzy:
Liu, Junfeng
Yao, Ji
Huang, Kun
Zhang, Qing
Ze, Li
Powiązania:
https://bibliotekanauki.pl/articles/2104766.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nonlinear characteristics
complex average method
multi-scale method
nonlinear design
control performance
Opis:
A tuned mass damper is a kind of vibration damping device which has been widely used in tall buildings, machinery, bridges, aerospace engineering and other fields. In practical engineering applications, due to large deformation caused by large displacement, errors in engineering constructions and the existence of limit devices, the structure and tuned mass dampers inevitably produce some nonlinear characteristics, but these nonlinearities are often ignored. The results of this study confirm that the nonlinearity of the structure and the mass damper should be considered in the process of optimal frequency design, otherwise there will be a large deviation between the design optimal frequency of the mass damper and the actual optimal frequency. In this paper, nonlinear characteristics of the tuned mass damper and the main structure are considered. The first-order differential equations are obtained by using the complex average method, and the nonlinear equations of the tuned mass damper system are derived by using the multi-scale method. On this basis, the parameters are determined. The numerical results show that the error of the approximate solution method is small in the given example. The nonlinear tuned mass damper with nonlinear design exhibits a better control performance.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 3; 463--477
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 70

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