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Hossein Bonakdari - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of geomorphological bank evolution of the alluvial threshold rivers based on Entropy Concept parameters
    Hydrological Sciences Journal, 2019
    Co-Authors: Azadeh Gholami, Hossein Bonakdari, Majid Mohammadian, Amir Hossein Zaji, Bahram Gharabaghi
    Abstract:

    The complex stream bank profiles in alluvial channels and rivers that are formed after reaching equilibrium has been a popular topic of research for many geomorphologists and river engineers. The e...

  • Predicting Shear Stress Distribution in Rectangular Channels Using Entropy Concept
    International Journal of Engineering - Transactions C: Aspects, 2015
    Co-Authors: Hossein Bonakdari, Mohtaram Tooshmalani, Zohreh Sheikh
    Abstract:

    This study makes use of the Tsallis Entropy to predict the shear stress distribution in rectangular channels. Given a definition of the Tsallis Entropy, it is maximized using the probability density function, which then is used to attain a novel shear stress equation. This is then employed for calculating the shear stress distribution in rectangular channels in different aspect ratios and finally, for viability, these calculations are compared with some relevant experimental results. This derived shear stress equation is capable of describing the variation of shear stress in both the wall and the bed of channels. The comparison shows that this equation appears to be efficient for predicting the shear stress distribution in rectangular open channels. The shear force percentage and mean values of the bed and wall shear stress calculated by the proposed equation have good agreement with the experiments.

  • Prediction of boundary shear stress in circular and trapezoidal channels with Entropy Concept
    Urban Water Journal, 2015
    Co-Authors: Zohreh Sheikh, Hossein Bonakdari
    Abstract:

    Relying on the power law to develop new relationships, the present study developed the Shannon Entropy Concept to predict shear stress distribution. The presented method was evaluated and compared with valid laboratory results and the shear stress distribution surveyed through this Concept in circular, circular with flat bed and trapezoidal channels. By increasing the flow depth in circular channels, the model presented herein gives an improved prediction of shear stress distribution, while in circular channels with flat bed it is better in predicting shear stress both at lower flow depth and subcritical flow conditions. In comparison, in trapezoidal channels the model is much better in predicting the shear stress distribution at lower flow depths. Accordingly, with a mean error percentage of 1.99% in circular channels, 3.69% in circular channels with flat bed and 4.1% in trapezoidal channels, this novel model shows good ability in predicting shear stress distribution.

  • Modeling of velocity fields by the Entropy Concept in narrow open channels
    KSCE Journal of Civil Engineering, 2014
    Co-Authors: Hossein Bonakdari, Marjan Moazamnia
    Abstract:

    To predict velocity field in narrow open channels, the Tsallis Entropy based on probability has been developed in this paper. Given a definition of the Tsallis Entropy, it is maximized by using the probability density function, which then is used to attain a velocity distribution equation. This is then employed for calculating the velocity distribution in narrow open channel under a wide range of discharge and water depth, and finally, for viability, these calculations are compared with some relevant field experimental results. By comparing the actual field data and the model results for estimating velocity distribution, this study highlights the application of the Tsallis Entropy Concept to predict it in narrow open channels. The obtained results showed that this theoretically generated equation is efficient for predicting the velocity distribution in narrow open channels with the maximum velocity taking place below the free surface.

  • Discharge Estimation by using Tsallis Entropy Concept
    2013
    Co-Authors: Marjan Moazamnia, Hossein Bonakdari
    Abstract:

    Flow-rate measurement in rivers under different conditions is required for river management purposes including water resources planning, pollution prevention, and flood control. This study proposed a new discharge estimation method by using a mean velocity derived from a 2D velocity distribution formula based on Tsallis Entropy Concept. This procedure is done based on several factors which reflect the basic hydraulic characteristics such as river bed slope, wetted perimeter, width, and water level that are easily obtained from rivers. This method avoids putting the environment at risk and significantly reduces time and costs. Validation of the method was carried out by comparing the results with measured values in the experimental sites. Predicted results are in good agreement with the measured data in a cross section of the Tiber River, Italy. Extended usage of this method will make it possible to measure discharge and better estimate the flow rate conveyed from rivers under different hydraulic conditions.

Hans Jürgen Korsch - One of the best experts on this subject based on the ideXlab platform.

  • A generalized Entropy measuring quantum localization.
    Annalen der Physik, 1999
    Co-Authors: B. Mirbach, Hans Jürgen Korsch
    Abstract:

    We present an Entropy Concept measuring quantum localization in dynamical systems based on time averaged probability densities. The suggested Entropy Concept is a generalization of a recently introduced [PRL 75, 326 (1995)] phase-space Entropy to any representation chosen according to the system and the physical question under consideration. In this paper we inspect the main characteristics of the Entropy and the relation to other measures of localization. In particular the classical correspondence is discussed and the statistical properties are evaluated within the framework of random vector theory. In this way we show that the suggested Entropy is a suitable method to detect quantum localization phenomena in dynamical systems.

  • A GENERALIZED Entropy MEASURING QUANTUM LOCALIZATION
    Annals of Physics, 1998
    Co-Authors: B. Mirbach, Hans Jürgen Korsch
    Abstract:

    Abstract We present an Entropy Concept measuring quantum localization in dynamical systems based on time averaged probability densities. The suggested Entropy Concept is a generalization of a recently introduced [ Phys. Rev. Lett. 75 (1995), 362] phase-space Entropy to any representation chosen according to the system and the physical question under consideration. In this paper we inspect the main characteristics of the Entropy and the relation to other measures of localization. In particular the classical correspondence is discussed and the statistical properties are evaluated within the framework of random vector theory. In this way we show that the suggested Entropy is a suitable method to detect quantum localization phenomena in dynamical systems.

Taiho Choo - One of the best experts on this subject based on the ideXlab platform.

  • A research on the estimation of coefficient roughness in open channel applying Entropy Concept
    Environmental Earth Sciences, 2018
    Co-Authors: Yeon Moon Choo, Gwan Seon Yun, Taiho Choo
    Abstract:

    Manning’s roughness coefficient is one of the most important parameters in establishing the plan, design, operation, and maintenance of the water resource projects for hydraulic engineers, and since the worth of this value has a significant effect on the analysis of the water level and flow rate distribution, it is very important to carry out the calculation of flood stage, design of the stream/river structure, and safety assessment of the stream. Due to the importance of these factors, the calculation of objective and quantitative roughness coefficient has long drawn attention from researchers at home and abroad. Many studies have been conducted to estimate the roughness coefficient based on the actual measurements for various types of streams, such as gravel and sand streams, and many others have produced experience equation for various levels of materials and relative depth. Despite many of these efforts, the roughness coefficient uses constant values when applied to the actual model or real design. This application is a major source of error in simulating flood and unsteady flow. To solve these problems, good results were obtained by attempting to calculate the roughness coefficient applied with the Entropy Concept in open-channel flow. In particular, the proposed roughness coefficient based on the measurements taken from laboratories under conditions showed very similar to the actual stream flow which was found to be about the same as the value from the unsteady flow. Accordingly, the newly developed roughness coefficient equation, which is the result of this study, is a very practical one formula that can be applied to the flood flow of real natural streams. It can also be used as an alternative to make up for the disadvantages of the Manning’s roughness coefficient.

  • Study of shear stress in laminar pipe flow using Entropy Concept
    Environmental Earth Sciences, 2017
    Co-Authors: Yeon Moon Choo, Taiho Choo, Gwan Seon Yun, Yong Been Kwon, Su Yong Sim
    Abstract:

    In fluid mechanics, the shear stress is calculated from the frictional force caused by viscosity and fluctuating velocity. Shear stress equations are used widely because of their simplicity. On the other hand, they have a critical limitation of requiring an energy gradient, which is generally difficult to estimate in practice. In particular, measuring the shear stress and velocity gradient on the boundary layer is difficult. The point velocity throughout the entire cross section is needed to calculate the velocity gradient. This study proposes the shear stress distribution equations for laminar flow based on Entropy theory using the mean velocity and Entropy coefficient. The proposed equations were compared with the measured shear stress distribution using Nikuradse’s data. The results revealed a correlation coefficient of approximately 0.99, indicating that the proposed method fits the Nikuradse’s data. Therefore, the shear stress distribution can be estimated easily and accurately using the proposed equations, which can be used in future for the management and design of a water pipeline.

  • Estimation of the maximum velocity using the Entropy Concept in an open channel
    Environmental Earth Sciences, 2016
    Co-Authors: Taiho Choo, Gwan Seon Yun, Hyeon Cheol Yoon, Hyun Seok Noh, Chang Yeon Bae
    Abstract:

    Accurate measurements and estimations of the river flow rate are essential elements for the effective management of water resources. The stage-discharge curve is a traditional method but it has limited applicability because of the loop form characteristics, which are caused by a tidal river, the backwater effect, and the sudden changes in water level during the flood season. Therefore, various discharge estimation methods have been studied for long periods. On the other hand, measurements and estimations of the maximum velocity, which is a technically important parameter, have been difficult. If the maximum velocity can be estimated, it will be possible to determine the flow velocity because the minimum velocity is always zero at the bed under open channel flow conditions. In addition, the maximum velocity always has one value regardless of the flow conditions, such as laminar flow, turbulent flow, and a cross-sectional shape. This means that the maximum velocity is used to estimate the mean velocity. Therefore, in the present paper, an estimation formula for the maximum velocity was proposed using the Entropy Concept. The accuracy was verified using 12 sets measured under non-uniform flow conditions in the laboratory. A comparison of the estimated value with the value actually measured showed very high accuracy.

  • The Estimation of Friction Velocity in an Open Channel by the Entropy Concept
    Journal of the Korea Academia-Industrial cooperation Society, 2015
    Co-Authors: Taiho Choo, Gwan Seon Yun, Hee Sam Son, Hyun Seok Noh
    Abstract:

    In order to demonstrate the flow properties of the river bed and the design of hydraulic structures, the estimation of friction velocity is essentially required. However, existing friction velocity equations such as Log method and Power law have trouble to estimate the friction velocity because a boundary condition and various hydraulic properties are changed constantly in near the wall. In the present study, therefore, a new friction velocity equation that can minimize the parameters and reduce an error was suggested. To verify accuracy and reliability for the proposed equation, Clauser method,   method, reynolds stress method by Dr. Song were compared with the proposed method by estimated Entropy parameter M for each channel. Consequently, the results show that uniform flow condition as well as non-uniform flow condition with highly accuracy nearly matched in case of accelerating non-uniform condition of R 2 =0.9621, Decelerating Non Uniform condition of R

  • An element technique development reflecting the Entropy Concept of the application to smart water grid
    KSCE Journal of Civil Engineering, 2013
    Co-Authors: Taiho Choo, Hyeon Cheol Yoon, Seung Jin Maeng
    Abstract:

    Recently the international trend of water management is changing from the supply to the demand management, shifting the paradigm of the water resource control. As a result, the Smart Water Grid as the next generation system is being studied and developed in many countries. Although many researchers have kept an eye on the system, the very important discharge estimation in a river is still in question. In many countries, the stage-discharge curve method has been used to predict discharge at a low or high stage in spite of its uncertainties. In order to improve the conventional problem, in the current study, the authors developed a new mean velocity estimation law reflecting hydraulic characteristics such as the bed slope, width, wetted perimeter, kinematic viscosity and etc. The proposed method is possible to estimate the maximum velocity which is difficult to measure in an open channel, and the reliable flow rate estimation is also possible by calculating the Entropy function called “Equilibrium state phi (M)” which presents a specific character of a river. The results present remarkable precision and show that the accurate estimation of discharge is possible at flood season.

B. Mirbach - One of the best experts on this subject based on the ideXlab platform.

  • A generalized Entropy measuring quantum localization.
    Annalen der Physik, 1999
    Co-Authors: B. Mirbach, Hans Jürgen Korsch
    Abstract:

    We present an Entropy Concept measuring quantum localization in dynamical systems based on time averaged probability densities. The suggested Entropy Concept is a generalization of a recently introduced [PRL 75, 326 (1995)] phase-space Entropy to any representation chosen according to the system and the physical question under consideration. In this paper we inspect the main characteristics of the Entropy and the relation to other measures of localization. In particular the classical correspondence is discussed and the statistical properties are evaluated within the framework of random vector theory. In this way we show that the suggested Entropy is a suitable method to detect quantum localization phenomena in dynamical systems.

  • A GENERALIZED Entropy MEASURING QUANTUM LOCALIZATION
    Annals of Physics, 1998
    Co-Authors: B. Mirbach, Hans Jürgen Korsch
    Abstract:

    Abstract We present an Entropy Concept measuring quantum localization in dynamical systems based on time averaged probability densities. The suggested Entropy Concept is a generalization of a recently introduced [ Phys. Rev. Lett. 75 (1995), 362] phase-space Entropy to any representation chosen according to the system and the physical question under consideration. In this paper we inspect the main characteristics of the Entropy and the relation to other measures of localization. In particular the classical correspondence is discussed and the statistical properties are evaluated within the framework of random vector theory. In this way we show that the suggested Entropy is a suitable method to detect quantum localization phenomena in dynamical systems.

Jakob Yngvason - One of the best experts on this subject based on the ideXlab platform.

  • The Entropy Concept for non-equilibrium states
    Proceedings. Mathematical physical and engineering sciences, 2013
    Co-Authors: Elliott H. Lieb, Jakob Yngvason
    Abstract:

    In earlier work we presented a foundation for the Second Law of Classical Thermodynamics in terms of the Entropy Principle. More precisely, we provided an empirically accessible axiomatic derivation of an Entropy function defined on all equilibrium states of all systems that has the appropriate additivity and scaling properties and whose increase is a necessary and sufficient condition for an adiabatic process between two states to be possible. Here, after a brief review of this approach, we address the question of defining Entropy for non-equilibrium states. Our conclusion is that it is generally not possible to find a unique Entropy that has all relevant physical properties. We do show, however, that one can define two Entropy functions, called $S_-$ and $S_+$, which, taken together, characterize the range of adiabatic processes that can occur between non-equilibrium states. The Concept of {\it comparability} of states with respect to adiabatic changes plays an important role in our reasoning.

  • the Entropy Concept for non equilibrium states
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2013
    Co-Authors: Elliott H. Lieb, Jakob Yngvason
    Abstract:

    In earlier work, we presented a foundation for the second law of classical thermodynamics in terms of the Entropy principle. More precisely, we provided an empirically accessible axiomatic derivati...