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Tytuł:
On strongly monotone flows
Autorzy:
Walter, Wolfgang
Powiązania:
https://bibliotekanauki.pl/articles/1294817.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
system of ordinary differential equations
initial value problem
comparison theorem
monotone flow
quasimonotonicity
Opis:
M. Hirsch's famous theorem on strongly monotone flows generated by autonomous systems u'(t) = f(u(t)) is generalized to the case where f depends also on t, satisfies Carathéodory hypotheses and is only locally Lipschitz continuous in u. The main result is a corresponding Comparison Theorem, where f(t,u) is quasimonotone increasing in u; it describes precisely for which components equality or strict inequality holds.
Źródło:
Annales Polonici Mathematici; 1997, 66, 1; 269-274
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-dimensional vertical Reynolds-Averaged Navier-Stokes equations versus one-dimensional Saint-Venant model for rapidly varied open channel water flow modelling
Autorzy:
Szydłowski, M.
Zima, P.
Powiązania:
https://bibliotekanauki.pl/articles/241158.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
mathematical modelling
Reynolds-averaged Navier-Stokes equations
Saint-Venant equations
free surface flow
rapidly varied flow
dam-break problem
Opis:
The paper concerns mathematical modelling of free surface open channel water flow. In order to simulate the flow two models are used -- two-dimensional vertical Reynolds-Averaged Navier-Stokes equations and one-dimensional Saint-Venant equations. The former is solved with SIPMLE algorithm of finite difference method using Marker and Cell technique to trace a free surface movement. The latter is solved using the finite volume method. The dam-break (water column collapse) problem on horizontal bottom is investigated as a test case. The calculated results are compared with each other. The numerical simulations are examined against laboratory experiment presented by Koshizuka et al (1995). The possibility of using the described models to simulate rapidly varied flow is discussed.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2006, 53, 4; 295-309
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of Dam-Break Flow by a Corrected Smoothed Particle Hydrodynamics Method
Autorzy:
Staroszczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/241454.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
dam-break problem
free surface flow
meshfree Lagrangian method
smoothed particle hydrodynamics
Opis:
The paper deals with numerical modelling of water flow which is generated by the break of a dam. The problem is solved by applying a smoothed particle hydrodynamics (SPH) method in which standard smoothing kernel functions are corrected in such a way that so-called linear reproducing conditions for kernel approximations and their gradients are satisfied. The proposed SPH model has been used to simulate a two-dimensional problem of the collapse of a water column inside a rectangular tank. The simulations illustrate the formation and subsequent propagation of a wave over the horizontal plane. It is shown that the model predictions of the changes of the advancing wave-front position, and of the changes of the free surface elevation of water, compare well with experimental data. Also, the results obtained with the corrected SPH method are compared with those given by the standard SPH method with no kernel correction. In addition, an impact of the surging wave against a vertical rigid wall is illustrated.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2010, 57, 1; 61-79
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of flow rate in square-sectioned duct bend
Pomiar strumienia płynu w kanale z łukiem kolana o przekroju kwadratowym
Autorzy:
Rup, K.
Malinowski, Ł.
Sarna, P.
Powiązania:
https://bibliotekanauki.pl/articles/280883.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
measurement of flow rate
inverse coefficient problem
Opis:
In this paper the authors describe an attempt to utilise installed square- sectioned elbows in order to measure the fluid flow rate. In order to practically accomplish the measurement of the volumetric flow rate of the air, a special research stand has been built, and square shaped elbows have been installed (80 × 80mm in dimension). The numerical computations were carried out using the software package FLUENT 6.2. The obtained results were compared to corresponding ones coming from orifice measurements and from experimental work available in the literature. The comparative analysis of the obtained numerical and experimental results evidenced a high degree of their conformity.
W pracy podjęto próbę wykorzystania zainstalowanych w kanałach przepływowych łuków kolan o przekroju kwadratowym do pomiaru strumienia objętości płynu. W tym celu wykorzystano opracowaną wcześniej metodę pomiaru pośredniego dla rurociągów o przekroju kołowym. Dla praktycznej realizacji pomiaru wspomnianego strumienia przepływu zbudowano stanowisko badawcze za łukiem kolana o przekroju poprzecznym w kształcie kwadratu (80 × 80mm). Obliczenia wykonano za pomocą pakietu FLUENT 6.2. Uzyskane rezultaty porównano z odpowiednimi zmierzonymi za pomocą kryzy pomiarowej oraz z innymi wynikami doświadczalnymi dostępnymi w literaturze. Z analizy porównawczej wynika wysoki stopień zgodności otrzymanych rezultatów pomiaru pośredniego.
Źródło:
Journal of Theoretical and Applied Mechanics; 2011, 49, 2; 301-311
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy project scheduling using constraint programming
Autorzy:
Relich, M.
Powiązania:
https://bibliotekanauki.pl/articles/118137.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Promocji Wiedzy
Tematy:
project cash flow
constraint satisfaction problem (CSP)
project portfolio
Opis:
The paper aims to present an application of constraint programming techniques for project portfolio scheduling taking into account the imprecision in activity duration and cost. Data specification in the form of discrete a-cuts allows combining distinct and imprecise data, and implementing a constraint satisfaction problem with the use of constraint programming. Moreover using a-cuts, optimistic, pessimistic, and several intermediate scenarios concerning the project scheduling and cash flows can be obtained and considered in terms of different risk levels.
Źródło:
Applied Computer Science; 2013, 9, 1; 3-16
1895-3735
Pojawia się w:
Applied Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Homotopy simulation of non-Newtonian Spriggs fluid flow over a flat plate with oscillating motion
Autorzy:
Ray, A. K.
Vasu, B.
Gorla, R. S. R.
Powiązania:
https://bibliotekanauki.pl/articles/265238.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ nieściśliwy
przepływy Stokes'a
płyn nienewtonowski
incompressible flow
oscillatory plate
Stokes second problem
HAM
non-Newtonian Spriggs fluid
Opis:
An incompressible flow of a non-Newtonian Spriggs fluid over an unsteady oscillating plate is investigated using the Homotopy Analysis Method (HAM). An analytic solution of sine and cosine oscillations of the plate has been obtained. The similarity transformation is introduced to reduce the governing partial differentia equations into a single non-linear dimensionless partial differential equation. The effects of the power index of Spriggs fluid and convergence control parameter of HAM for the flow are studied extensively. The range of the convergence control parameter for convergence of series solution for different values of the power index of Spriggs fluid is obtained. The solution for a Spriggs fluid is noticeably different from the solution obtained for a Newtonian fluid. The influences of the shear thinning and shear thickening fluid on the velocity profile are shown graphically. The transient flow effect is higher for non-Newtonian Spriggs fluid than that of a Newtonian fluid. It is also observed that the interval to reach the steady state for the cosine case is less than the sine case. The applications of Stokes’ second problem have been widely found in the variety of fields of biomedical, medical, chemical, micro and nanotechnology.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 359-385
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelowanie matematyczne procesu wspomagającego projektowanie narzędzi do obróbki elektrochemicznej
Mathematical modeling of assisted process of electrochemical treatment tools designing
Autorzy:
Paczkowski, T.
Sawicki, J.
Powiązania:
https://bibliotekanauki.pl/articles/2072797.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
obróbka elektrochemiczna
przepływ elektrolitu
modelowanie matematyczne
zagadnienie odwrotne
electrochemical machining
electrolyte flow
mathematical modeling
inverse problem
Opis:
W pracy przedstawiono metodę projektowania elektrody roboczej w obróbce elektrochemicznej. Przedstawiona metoda polega na porównaniu wyników symulacji procesu obróbki elektrochemicznej w postaci kształtu elektrod i ich odpowiedniej korekcie. Zagadnienie rozwiązano wykorzystując układ równań opisujących ewolucję kształtu powierzchni obrabianej oraz przepływ mieszaniny elektrolitu i gazu w szczelinie międzyelektrodowej. Proces projektowania elektrody roboczej przedstawiono dla powierzchni o tworzących krzywoliniowych oraz osiowosymetrycznej.
A method for designing a working electrode in electrochemical treatment is presented in the paper. The presented method is based on the comparison of simulation results of electrochemical treatment in a form of electrodes shape and their appropriate adjusting. The issue was solved using a system of equations describing the evolution of machined surface shape and electrolyte/ gas mixture flow in the inter-electrode gap. The design process of working electrode is shown for the surface of curvilinear and axisymmetric generatrices.
Źródło:
Inżynieria i Aparatura Chemiczna; 2014, 6; 400--402
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resource and Task Allocation Algorithm for WAN-based Distributed Computing Environment
Autorzy:
Markowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/226934.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
capacity and flow assignment problem
distributed computing
resource management
wide area networks
Opis:
In the paper an approximate algorithm for optimizing of distributed computing WAN network is proposed. Distributed computing systems become the common tools in different kind of business, science and even entertainment. In order to minimize processing time of data and utilize spare resources available on remote systems, many companies and institutions decide to build and maintain own wide area networks (WAN) for ensuring reliable and secure distributed processing of data. Design of WANs in concerned with solving different optimization problems, like routing assignment, capacities of channel selection, resource (i.e. servers, management centre) allocation. Due to peculiar structure of wide area networks and nature of protocols, proper optimization methods and algorithms should be constructed for WAN-based distributed computing systems. In the paper the model of the distributed environment, built on WAN infrastructure is presented. Then, the optimization problem for routing assignment, channel capacities assignment and grid management center (data repository) allocation is formulated. Finally, an approximate algorithm is presented for formulated problem. Proposed algorithm, observations and conclusions should effect in improving of distributed computing systems design.
Źródło:
International Journal of Electronics and Telecommunications; 2010, 56, 2; 197-202
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Permutation, no-wait, no-idle flow shop problems
Autorzy:
Makuchowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/229973.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
flow shop problem
permutation constraint
no-wait constraint
no-idle constraint
permutation-graph models
Opis:
The paper compares the schedules of different variants of the flow shop problem, i.e. permutation, no waiting and no idle flow shop problems. It is assessed the impact of the constraints on the extension of the schedules and correlations of the length of the schedules for these variants. It is also examined the effectiveness of a set of insert type algorithms. The efficiency of the algorithms is tested on well-known literature benchmarks.
Źródło:
Archives of Control Sciences; 2015, 25, 2; 189-199
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tiling by squares, Kirchhoff’s laws and a flow problem in the economy
Autorzy:
Maciuk, Arkadiusz
Smoluk, Antoni
Powiązania:
https://bibliotekanauki.pl/articles/421315.pdf
Data publikacji:
2017
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
squarings
digraph
Kirchhoff’s laws
flow problem in the economy
Opis:
The problem of tiling by squares was formulated more than one hundred years ago and has been mostly regarded as an interesting mathematical issue in geometry, yet without any special practical associations. In addition to a historical outline of the problem, this paper demonstrates how Smith’s 1940 method using digraphs helps associate an issue linked to two-dimensional dissection or packaging with such economic problems as transportation network planning, researching linkages between suppliers and the like. We also discuss simple perfect squared rectangles whose relevant laws of nature are as yet unknown, according to the principle that elegant scientific structures sooner or later find their equivalents in the real world.
Źródło:
Didactics of Mathematics; 2017, 14(18); 33-44
1733-7941
Pojawia się w:
Didactics of Mathematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The application of Beck’s method combined with FEM and Trefftz functions to determine the heat transfer coefficient in a minichannel
Autorzy:
Maciejewska, B.
Powiązania:
https://bibliotekanauki.pl/articles/281153.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Beck’s method
FEM
Trefftz functions
heat transfer coefficient
inverse heat conduction problem
flow boiling
Opis:
The aim of this study is to determine the heat transfer coefficient between the heated surface and the boiling fluid flowing in a minichannel on the basis of experimental data. The calculation model is based on Beck’s method coupled with the FEM and Trefftz functions. The Trefftz functions used in the Hermite interpolation are employed to construct the shape functions in the FEM. The unknown local values of the heat transfer coefficient at the foil- -fluid contact surface are calculated from Newton’s law. The temperature of the heated foil and the heat flux on the foil surface are determined by solving a two-dimensional inverse heat conduction problem. The study is focused on the identification of the heat transfer coefficients in the subcooled boiling region and the saturated nucleate boiling region. The results are compared with the data obtained through the one-dimensional method. The investigations also reveal how the smoothing of measurement data affects calculation results.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 1; 103-116
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Simulation of Nonlinear Water Wave Problems
Autorzy:
Lo, D. C.
Hu, Jia-Shen
Lin, I-Fu
Powiązania:
https://bibliotekanauki.pl/articles/116613.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Weather Navigation
Numerical Simulation
Oceanography
Nonlinear Water Wave Problem
Navier-Stokes Equations
Solitary Waves
Free-Surface Flow Problem
Streamfunction Vorticity Formulation
Opis:
The main purpose of present paper aims at the establishment of a numerical model for solving the nonlinear water wave problems. The model is based on the Navier-Stokes equations with the consideration of a free-surface through the streamfunction-vorticity formulation. The main advantage of the streamfunction-vorticity formulation is that pressure field can be eliminated from the Navier-Stokes equations. To demonstrate the model feasibility, the present studies are first concentrated on problems including the collision of two solitary waves with different amplitudes, and the overtaking collision of two solitary waves. Then, the model is also applied to a solitary wave passes over the submerged obstacle in a viscous fluid. Finally, the application of present study is also to simulate the generation of solitary waves by underwater moving object. All examples give very promising results, those applications reveal that present formulation is a very powerful approach to simulate the fully nonlinear water wave problems.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2008, 2, 2; 137-142
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Analysis of the Problem of Flow Past a Cylindrical Body Applying the R-Functions Method and The Galerkin Method
Autorzy:
Lamtyugova, S.N.
Sidorov, M. V.
Powiązania:
https://bibliotekanauki.pl/articles/410652.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
viscous incompressible fluid
flow problem
R-functions method
Galerkin method
Opis:
The article considers the stationary problem of viscous incompressible fluid flow past a cylindrical body. For solving the problem it is proposed a numerical method, based on the joint use of R-functions method and the Galerkin method. The computational experiment has been conducted for the task of flow past square cylinder for different Reynolds numbers.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2014, 3, 3; 43-50
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vortex in cell method for exterior problems
Metoda cząstek wirowych dla zagadnień zewnętrznych
Autorzy:
Kudela, H.
Kozłowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/279735.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
vortex method
flow past cylinder
external problem
Opis:
The ”vortex in cell” method was used to model the flow past a solid body. Problems connected with flows past a body belong to the category of exterior problems. The main difficulty here is to establish the boundary condition far from the body, to solve equations of motion on the numerical mesh. The mesh requires a limited calculation area and the boundary condition far from the body. A method of obtaining the accurate boundary condition in such flows was presented. Testing calculations were performed for the flow past a cylinder for a wide range of Reynolds numbers. The flow past an ellipse was also performed. A good agreement with experimental results and calculations of other researchers was obtained.
Do obliczeń zastosowano metodę cząstek wirowych typu „wir w komórce”. Rzeczywisty obszar przepływu transformowano używając odwzorowania konforemnego. Opisano sposób wyznaczania zewnętrznego warunku brzegowego daleko od ciała, wykorzystując asymptotyczne własności rozwiązania równania Laplace’a. Wyniki numeryczne przedstawiono dla opływu walca w szerokim przedziale liczb Reynoldsa (550 < Re > 9500) oraz cienkiej elipsy. Obliczenia porównano z danymi eksperymentalnymi i wynikami numerycznymi innych badaczy, uzyskując bardzo dobrą zgodność.
Źródło:
Journal of Theoretical and Applied Mechanics; 2009, 47, 4; 779-796
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient heuristic for non-linear transportation problem on the route with multiple ports
Autorzy:
Krile, S.
Powiązania:
https://bibliotekanauki.pl/articles/260030.pdf
Data publikacji:
2013
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
non-linear transportation problem
Multi-destination Routing Problem
Minimum Cost Multi-Commodity Flow Problem
Capacity Management of Container Ships
Opis:
We need a better transport planning tool for loading maximization and transport cost minimization on the voyage route with multiple loading/unloading (discharging) ports. The implemented heuristic algorithm is able to find out an appropriate routing sequence with maximal earnings and profit. In the same time it looks for minimal loading/discharging and transshipment costs, but with fulfillment of cargo demands in a number of ports on the route. The efficient algorithm for optimal transport of N cargo loads (e.g. contingent of containers) for ships with limited capacity is being developed. This efficient tool may significantly reduce transport costs and ensure maximal profit to freight forwarders. Also, it can be applied for supply chain management of different goods from numerous vendors. The proposed algorithm shows acceptable complexity that means that such optimization tool can be used in shipping supported with limited computing power.
Źródło:
Polish Maritime Research; 2013, 4; 80-86
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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