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Tytuł:
Adaptive modeling of reliability properties for control and supervision purposes
Autorzy:
Dettmann, K. U.
Söffker, D.
Powiązania:
https://bibliotekanauki.pl/articles/907535.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
niezawodność
estymacja parametrów
kumulacja uszkodzeń
reliability
parameter estimation
damage accumulation
probabilistic simulation
Opis:
Modeling of reliability characteristics typically assumes that components and systems fail if a certain individual damage level is exceeded. Every (mechanical) system damage increases irreversibly due to employed loading and (mechanical) stress, respectively. The main issue of damage estimation is adequate determination of the actual state-of-damage. Several mathematical modeling approaches are known in the literature, focusing on the task of how loading effects damage progression (e.g., Wöhler, 1870) for wear processes. Those models are only valid for specific loading conditions, a priori assumptions, set points, etc. This contribution proposes a general model, covering adequately the deterioration of a set of comparable systems under comparable loading. The main goal of this contribution is to derive the loading-damage connection directly from observation without assuming any damage models at the outset. Moreover, the connection is not investigated in detail (e.g., to examine the changes in material, etc.) but only approximated with a probabilistic approach. The idea is subdivided into two phases: A problem-specific relation between loading applied (to a structure, which contributes to the stress) and failure is derived from simulation, where a probabilistic approach only assumes a distribution function. Subsequently, an adequate general model is set up to describe deterioration progression. The scheme will be shown through simulation-based results and can be used for estimation of the remaining useful life and predictive maintenance/control.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 3; 479-486
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The forecasting potential of adaptive models in tourism
Potencjał prognostyczny modeli adaptacyjnych w turystyce
Autorzy:
Aleksandrova, Anna
Aigina, Ekaterina
Dombrovskaya, Veronika
Powiązania:
https://bibliotekanauki.pl/articles/2032668.pdf
Data publikacji:
2021-12-31
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
prognozowanie
modele adaptacyjne
ruch turystyczny
metoda Holta-Wintersa
forecasting
adaptive modeling
tourist flows
Holt-Winters method
Opis:
The article discusses forecasting as one of the special scientific research areas which contribute to the assessment of tourist activity development prospects, the identification of key tourism development factors and effective management decision criteria. The study provides an overview of modern research methods used in Russia and other countries for making forecasts in the field of tourism. It aims at assessing the predictive capabilities of adaptive modeling, not frequently used currently in tourism research, for the quantitative analysis of tourist flows using the example of Barcelona, a major urban tourist destination in the pre-pandemic period. An example of a forecast for tourist numbers based on adaptive models is proposed, one of the key indicators showing tourist region success which have proven successful in the study of processes with a dynamic but unstable character.
Autorki omawiają prognozowanie jako szczególny obszar badań naukowych, który pomaga ocenić perspektywy rozwoju aktywności turystycznej, zidentyfikować kluczowe czynniki procesu zmian zachodzących w turyzmie oraz kryteria efektywnego zarządzania. Artykuł zawiera przegląd nowoczesnych metod badawczych stosowanych w Rosji i w innych krajach do sporządzania prognoz w dziedzinie turystyki. Celem opracowania jest ocena predyktywnych możliwości modelowania adaptacyjnego, obecnie niezbyt często stosowanego w badaniach turystycznych, do przeprowadzania ilościowej analizy ruchu turystycznego. Na podstawie danych dotyczących Barcelony – dużego miejskiego centrum turystycznego w czasach przed pandemią – opierając się na modelach adaptacyjnych, przedstawiono przykład prognozy liczby podróżnych. Jest to jeden z głównych wskaźników sukcesu turystycznego ujawnionego w trakcie badania procesów o dynamicznym, lecz niestałym charakterze.
Źródło:
Turyzm; 2021, 31, 2; 181-196
0867-5856
2080-6922
Pojawia się w:
Turyzm
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radio Channels Modeling for Adaptive Antennas Applications – Analysis of Elevation, Azimuth and Delay Spread
Autorzy:
Łapszow, R.
Modelski, J.
Powiązania:
https://bibliotekanauki.pl/articles/307848.pdf
Data publikacji:
2014
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
adaptive antenna
cellular systems
radio channel modeling
Opis:
Research of modeling urban environment channel has been presented in this paper. Measurements were performed for 2.2 GHz band. Test environment was based on existing 3G sites. Elevation, delay and azimuth spreads were analyzed. Both theoretical channel modeling and similar tests campaign were subject for analysis in this paper. Based on radio channel modeling further investigations are presented and the adaptive antenna implementation was proposed.
Źródło:
Journal of Telecommunications and Information Technology; 2014, 2; 35-41
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelowanie adaptacyjnego sterowania procesem blokowania przekładni hydrokinetycznej autobusów lotniskowych
Modeling adaptive controlling of hydrokinetic torque converter blocking process in airport buses
Autorzy:
Koralewski, G.
Wrona, R.
Powiązania:
https://bibliotekanauki.pl/articles/314454.pdf
Data publikacji:
2017
Wydawca:
Instytut Naukowo-Wydawniczy "SPATIUM"
Tematy:
przekładnia hydrokinetyczna
układ napędowy
sterownik silnika
power transmission system
engine control unit (ECU)
torque converter
Opis:
Artykuł zawiera syntezę matematycznego modelu adaptacyjnego sterowania procesem blokowania przekładni hydrokinetycznej w układzie przeniesienia napędu autobusów lotniskowych. Może on być wykorzystany w sterownikach automatycznych hydromechanicznych skrzyń biegów do realizacji sterowania blokowaniem przekładni hydrokinetycznej podczas ruchu autobusu. Sterowanie adaptacyjne pozwala uwzględnić zmienność różnych czynników eksploatacyjnych takich jak: warunki drogowe, stan pracy silnika i przekładni hydrokinetycznej oraz przede wszystkim zmienność masy autobusu, co jest bardzo istotne w przypadku autobusów lotniskowych. Celem sterowania adaptacyjnego jest zwiększenie płynności jazdy autobusu a tym samym poprawa komfortu przewozu pasażerów i ich bezpieczeństwa.
The article contains a synthesis of the mathematic model of adaptive controlling of hydrokinetic torque blocking process in the power transmission system in airport buses. It can be used in automatic hydro-mechanical gearbox controllers to achieve controlling hydrokinetic torque converter by blocking, as the bus moves. Adaptive controlling allows to consider the changeability of various operating factors, such as: road conditions, engine operating conditions and hydrokinetic torque converter operating conditions, and, above all, buss weight variability, which is very significant in the case of airport buses. The aim of adaptive controlling is to increase the bus movement smoothness, and, at the same time, improvement of the passengers’ comfort and safety of transport.
Źródło:
Autobusy : technika, eksploatacja, systemy transportowe; 2017, 18, 6; 800-805, CD
1509-5878
2450-7725
Pojawia się w:
Autobusy : technika, eksploatacja, systemy transportowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie adaptacyjnej hurtowni danych do modelowania scenariuszy biznesowych organizacji
Business scenarios modeling with an adaptive data warehouses
Autorzy:
Śmiałkowska, Bożena
Dudek, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/432149.pdf
Data publikacji:
2014
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
data warehouse
business scenarios
adaptive mechanisms
Opis:
The processes of modeling, design and verification of business scenarios falls into one of the most difficult areas of analytical systems. In order to simplify the implementation of those processes and introduce brand new business scenarios, it is necessary to access credible, integrated, and historical information. The article presents a data warehouse model, which is equipped with an adaptive mechanisms and servo adjustment methods (changing information needs of the organization) that will power the processes of construction, verification and modeling of business scenarios with the necessary data associated with the current and projected strategy of the organization. In addition, the data warehouse will provide analysts (for the process of creating business scenarios) with highly credible and historical data obtained from previous organization activities. This will help them (through simulation) to assess the expected scenarios impact.
Źródło:
Informatyka Ekonomiczna; 2014, 1(31); 365-373
1507-3858
Pojawia się w:
Informatyka Ekonomiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved Control of Mesh Density in Adaptive Tetrahedral Meshes for Finite Element Modeling
Udoskonalona kontrola gęstości siatki w adaptacyjnych siatkach tetrahedralnych dla metody elementów skończonych
Autorzy:
Ostaszewska-Liżewska, Anna
Kopala, Dominika
Szewczyk, Roman
Powiązania:
https://bibliotekanauki.pl/articles/2090885.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
adaptive meshing
tetrahedral meshing
FEM modeling
magnetodynamic systems
siatki adaptacyjne
siatki tetrahedralne
modelowanie MES
układy magnetodynamiczne
Opis:
Tetrahedral meshing is the critical element of finite element modeling. Recently, adaptive meshing has been commonly used. In such meshing, according to the Delaunay method, mesh density is connected with the curvature of modeled object’s edge. Such a method is especially efficient during the modeling of mechanical systems. However, the efficiency of commonly used meshing algorithms is strongly limited in surface-focused phenomena, such as eddy current induced by magneto-dynamic processes. The paper proposes the improved method of Delaunay meshing considering the specific requirements of magnetodynamic systems. In the proposed method, tetrahedral mesh density may be flexibly modified according to the needs of modeled physical phenomena, such as eddy current density. As a result, physical effects may be efficiently and accurately described in finite element models. The paper presents the example of implementing the proposed solution for cylindrical wire. The complete source code is available as open-source software for further practical use and development.
Siatki tetrahedralne są kluczowym elementem w metodzie elementów skończonych. Ostatnio powszechnie stosowane są siatki adaptacyjne, w których zgodnie z metodą Delaunay’a gęstość powiązana jest z krzywizną krawędzi modelowanego obiektu. Metoda ta jest wyjątkowo efektywna w przypadku modelowania układów mechanicznych. Niemniej jednak wydajność powszechnie stosowanych metod siatkowania jest mocno ograniczona w przypadku zjawisk skupionych na powierzchni modelu, takich jak prądy wirowe indukowane przez procesy magnetodynamiczne. Artykuł przedstawia propozycję ulepszonej metody siatkowania metodą Delaunay’a, uwzględniającą specyficzne wymagania układów magnetodynamicznych. W proponowanej metodzie gęstość siatki tetrahedralnej może być elastycznie modyfikowana odpowiednio do potrzeb modelowanego zjawiska, takiego jak gęstość prądów wirowych. W rezultacie efekty fizyczne mogą być efektywnie i dokładnie opisane za pomocą modeli stworzonych metodą elementów skończonych. W artykule przedstawiono przykład implementacji zaproponowanego rozwiązania dla przewodu cylindrycznego. Pełny kod źródłowy dostępny jest w formie otwartej licencji do dalszego rozwoju i użycia w praktyce.
Źródło:
Pomiary Automatyka Robotyka; 2022, 26, 2; 23--28
1427-9126
Pojawia się w:
Pomiary Automatyka Robotyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limitations of WSSUS modeling of stationary underwater acoustic communication channel
Autorzy:
Kochańska, I.
Nissen, I.
Powiązania:
https://bibliotekanauki.pl/articles/331730.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
underwater communications
impulse response
stationary time
stationary bandwidth
adaptive communications
WSSUS modeling
Opis:
Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel. Due to their large variability, there is a need for adaptive matching of the UAC systems signaling to the transmission properties of the channel. This requires a knowledge of instantaneous channel characteristics, in terms of the specific parameters of stochastic models. The wide-sense stationary uncorrelated scattering (WSSUS) assumption simplifies the estimation of terrestrial wireless channel transmission properties. Although UAC channels are hardly ever WSSUS, the rationale of such a stochastic modeling is that over a short period of time, and for a limited frequency range, this assumption is reasonably satisfied. The limits of application of the local-sense stationary uncorrelated scattering (LSSUS) model are determined by the stationary time and frequency. This paper presents the results of LSSUS model analysis for UAC channel measurements gathered by the former Research Department for Underwater Acoustics and Marine Geophysics (FWG), now part of the WTD71, during the SIMO experiment in the Bornholm Basin of the Baltic Sea.
Źródło:
Hydroacoustics; 2016, 19; 229-238
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the simple additive modeling of the first principle model inaccuracies for the offset–free process control
Autorzy:
Czeczot, J.
Łaszczyk, P
Powiązania:
https://bibliotekanauki.pl/articles/205682.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
first principle process modeling
modeling inaccuracies compensation
model-based control
adaptive control
Opis:
In this paper, the method for simple additive modeling of the first principle model inaccuracies for the offset-free process control is presented. Starting from transformation of the general nonlinear state model into the input affine dynamical equation describing directly the controlled variable, it is shown how to compensate for the potential modeling inaccuracies by lumping them into a single additive parameter. Its on-line estimation procedure based only on the measurement data collected from the process is very simple and effective and the estimate converges without any additional excitation of the process. The discussion on how to apply the suggested model as a basis for the chosen model-based control techniques is presented, and for the processes of the higher relative order, the practical simplification of this approach is shown. The experimental results show the practical applicability of the considered approach for the synthesis of the open loop InternalModel Controller (IMC) and of the Balance-Based Adaptive Controller (B-BAC).
Źródło:
Control and Cybernetics; 2014, 43, 2; 261-277
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indirect adaptive controller based on a self-structuring fuzzy system for nonlinear modeling and control
Autorzy:
Qi, R.
Brdyś, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/929998.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sterowanie rozmyte
model rozmyty
stabilność
fuzzy control
self-structuring fuzzy model
on-line modeling
stability
Opis:
In this paper, a unified nonlinear modeling and control scheme is presented. A self-structuring Takagi-Sugeno (T-S) fuzzy model is used to approximate the unknown nonlinear plant based on I/O data collected on-line. Both the structure and the parameters of the T-S fuzzy model are updated by an on-line clustering method and a recursive least squares estimation (RLSE) algorithm. The rules of the fuzzy model can be added, replaced or deleted on-line to allow a more flexible and compact model structure. The overall controller consists of an indirect adaptive controller and a supervisory controller. The former is the dominant controller, which maintains the closed-loop stability when the fuzzy system is a good approximation of the nonlinear plant. The latter is an auxiliary controller, which is activated when the tracking error reaches the boundary of a predefined constraint set. It is proven that global stability of the closed-loop system is guaranteed in the sense that all the closed-loop signals are bounded and simulation examples demonstrate the effectiveness of the proposed control scheme.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2009, 19, 4; 619-630
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power-Ground Plane Impedance Modeling Using Deep Neural Networks and an Adaptive Sampling Process
Autorzy:
Goay, Chan Hong
Cheong, Zheng Quan
Low, Chen En
Ahmad, Nur Syazreen
Goh, Patrick
Powiązania:
https://bibliotekanauki.pl/articles/2200709.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
adaptive sampling
deep neural networks
deep learning
power-ground plane
Z-parameters
Opis:
This paper proposes a deep neural network (DNN) based method for the purpose of power-ground plane impedance modeling. A composite DNN model, which is a combination of two DNNs is used to predict the Z-parameters of power ground planes from their design parameters. The first DNN predicts the normalized Z-parameters whereas the second DNN predicts the original maximum and minimum values of the nonnormalized Z-parameters. This allows the method to retain a high accuracy when predicting responses that have large variations across designs, as is the case with the Z-parameters of the power-ground planes. We use the adaptive sampling algorithm to generate the training and validation samples for the DNNs. The adaptive sampling algorithm starts with only a few samples, then slowly generates more samples in the non-linear regions within the design parameters space. The level of non-linearity of the regions is determined by a surrogate model which is also trained using the generated samples as well. If the surrogate model has poor prediction accuracy in a region, then the adaptive sampling algorithm will generate more samples in that region. A shallow neural network is used as the surrogate model for non-linearity determination of the regions since it is faster to train and update. Once all the samples have been generated, they will be used to train and validate the composite DNN models. Finally, we present two examples, a square-shaped power ground plane and a squareshaped power ground plane with a hollow square at the center to demonstrate the robustness of the DNN composite models.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 4; 793--798
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Artificial adaptive agent model characterized by learning and fairness in the ultimatum games
Autorzy:
Hayashida, T.
Nishizaki, I.
Katagiri, H.
Powiązania:
https://bibliotekanauki.pl/articles/308565.pdf
Data publikacji:
2007
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
oxidation
kinetics
modeling
silicon
silicon-germanium
Opis:
This paper examines the result of the experimental research on the ultimatum games through simulation analysis. To do so, we develop agent-based simulation system imitating the behavior of human subjects in the laboratory experiment by implementing a learning mechanism involving a concept of fairness. In our agent-based simulation system, mechanisms of decision making and learning are constructed on the basis of neural networks and genetic algorithms.
Źródło:
Journal of Telecommunications and Information Technology; 2007, 4; 36-44
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Robustifying analysis of the direct adaptive control of unknown multivariable nonlinear systems based on a new neuro-fuzzy method
Autorzy:
Theodoridis, D. C.
Boutalis, Y.S.
Christodoulou, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/91598.pdf
Data publikacji:
2011
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
nonlinear systems
control
neuro-fuzzy dynamical system
fuzzy systems
FS
fuzzy recurrent high order neural network
F-RHONN
adaptive regulator
parameter
“Hopping”
“Modified Hopping”
modeling errors
asymptotic regulation
Opis:
In this paper, we are dealing with the problem of directly regulating unknown multivariable affine in the control nonlinear systems and its robustness analysis. The method employs a new Neuro-Fuzzy Dynamical System definition, which uses the concept of Fuzzy Systems (FS) operating in conjunction with High Order Neural Networks. In this way the unknown plant is modeled by a fuzzy - recurrent high order neural network structure (F-RHONN), which is of the known structure considering the neglected nonlinearities. The development is combined with a sensitivity analysis of the closed loop in the presence of modeling imperfections and provides a comprehensive and rigorous analysis showing that our adaptive regulator can guarantee the convergence of states to zero or at least uniform ultimate boundedness of all signals in the closed loop when a not-necessarily-known modeling error is applied. The existence and boundedness of the control signal is always assured by employing a method of parameter “Hopping” and “Modified Hopping”, which appears in the weight updating laws. Simulations illustrate the potency of the method showing that by following the proposed procedure one can obtain asymptotic regulation despite the presence of modeling errors. Comparisons are also made to simple recurrent high order neural network (RHONN) controllers, showing that our approach is superior to the case of simple RHONN’s.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2011, 1, 1; 59-79
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Overview of adaptive and low-rank approximation algorithms for modeling influence of electromagnetic waves generated by cellphone antenna on human head
Autorzy:
Głut, Barbara
Paszyński, Maciej
Powiązania:
https://bibliotekanauki.pl/articles/2097964.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
mesh generation
mesh adaptation
Pennes bioheat equations
time-harmonic Maxwell equations
sparse factorization
low rank approximation
Opis:
This paper presents an overview of formulations and algorithms that are dedicated to modeling the influence of electromagnetic waves on the human head. We start from h adaptive approximation of a three-dimensional MRI scan of the human head. Next, we solve the time-harmonic Maxwell equations with a 1.8 GHz cellphone antenna. We compute the specific absorption rate used as the heat source for the Pennes bioheat equation modeling the heat generated by EM waves inside the head. We propose an adaptive algorithm mixed with time-stepping iterations where we simultaneously refine the computational mesh, solve the Maxwell and Pennes equations, and iterate the time steps. We employ the sparse Gaussian elimination algorithm with the low-rank compres-sion of the off-diagonal matrix blocks for the factorization of the matrices. We conclude with the statement that 15 minutes of talking with a 1.8 GHz antenna with one watt of power results in increased brain tissue temperatures (up to 38.4◦C).
Źródło:
Computer Science; 2021, 22 (4); 433--461
1508-2806
2300-7036
Pojawia się w:
Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive control scheme based on the least squares support vector machine network
Autorzy:
Mahmoud, T. K.
Powiązania:
https://bibliotekanauki.pl/articles/930155.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
modelowanie systemu
system nieliniowy
system sterowania
sieć neuronowa
maszyna wektorów wspierających
support vector machine (SVM)
neural network
nonlinear system modeling
nonlinear system control
pH control
Opis:
Recently, a new type of neural networks called Least Squares Support Vector Machines (LS-SVMs) has been receiving increasing attention in nonlinear system identification and control due to its generalization performance. This paper develops a stable adaptive control scheme using the LS-SVM network. The developed control scheme includes two parts: the identification part that uses a modified structure of LS-SVM neural networks called the multi-resolution wavelet least squares support vector machine network (MRWLS-SVM) as a predictor model, and the controller part that is developed to track a reference trajectory. By means of the Lyapunov stability criterion, stability analysis for the tracking errors is performed. Finally, simulation studies are performed to demonstrate the capability of the developed approach in controlling a pH process.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 4; 685-696
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling the hydrodynamic interactions between the river morphology and navigation channel operations
Autorzy:
Badawy, Neveen Abdel-Mageed
El-Hazek, Alaa N.
Elsersawy, Hossam Mohamed
Mohammed, Ebtesam Rezk
Powiązania:
https://bibliotekanauki.pl/articles/2048502.pdf
Data publikacji:
2021
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
adaptive hydraulics (ADH) model
draw down
navigation channel
the Nile River
restricted waterway
return flow
shear stress
Opis:
The Nile River is the main route for inland navigation in Egypt. The vessels navigating through inland waterways generate complex physical forces that need to be studied extensively. Quantifying the effects of vessels sailing along a waterway is a complex problem because the river flow is unsteady and the river bathymetry is irregular. This paper aims to investigate the hydrodynamic effects resulting from the movement of vessels such as return currents around the vessel, the draw down of the water surface, under keel clearance, and the shear stress induced by vessels operating in the Nile River. Modeling such effects has been performed by applied the two-dimensional ADH (adaptive hydraulics) model to a river reach for different navigation channel operation scenarios. The obtained results show that the draw down heights, the water fluctuation, and the shear stress magnitude are larger when the river cross sectionals are narrow and the shallow water depths. These river sections are considered more disposed to bed erosion and it is morphologically unsafe. The section having the narrowest width and the lowest depth was associated with the largest drawdown percentages of 98.3% and 87.3% in one-way and two-way scenarios. While the section having the widest width and the largest depth was associated with the least drawdown percentages of 48.5% and 51.9% in one-way and two-way scenarios. The section having the narrowest width and the lowest depth was associated with the largest fluctuations of 22.0 cm and 41.9 cm in one-way and two-way scenarios. While the section having the widest width and the largest depth was associated with the least fluctuations of 0.6 cm and 1.8 cm in one-way and two-way scenarios. The section having the narrowest width and the lowest depth was the worst section for under keel clearance of 5.0 cm and 33.3 cm in one-way and two-way scenarios. While the section having the widest width and the largest depth was the best section, where its clearance values were 183.2 cm and 155.0 cm in one-way and two-way scenarios. It is concluded that a numerical model is a valuable tool for predicting and quantifying the hydrodynamic effects of vessels moving through a two-dimensional flow field and can be used to evaluate different scenarios that are difficult to measure in the field or a physical model. Also, it provides visualization products that help us understand the complicated forces produced by vessels moving in a navigation channel.
Źródło:
Journal of Water and Land Development; 2021, 51; 1-10
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 18

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