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Judith Rivlin - One of the best experts on this subject based on the ideXlab platform.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

Rony Wallach - One of the best experts on this subject based on the ideXlab platform.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

Galina Grigorin - One of the best experts on this subject based on the ideXlab platform.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

  • A Comprehensive Mathematical Model for transport of soil-dissolved chemicals by overland flow
    Journal of Hydrology, 2001
    Co-Authors: Rony Wallach, Galina Grigorin, Judith Rivlin
    Abstract:

    The Model developed in this study simulates the contamination of overland flow by soil chemicals that reside near its surface during a surface runoff event. The Model includes mass-balance equations for both water flow and chemical transport in the soil profile and surface runoff. A rate-limited mass transfer through an overland-flow boundary layer at the soil overland flow interface controls the dissolved chemical transfer from soil solution to overland flow, once formed. The Model predicts water flow and chemical transport in the soil profile prior to the rainfall ponding (when overland flow starts) and during the surface runoff event. The predictions of these variables, together with the total load to the surface runoff, were successfully compared with the measured data of Hubbard et al. [Trans. ASAE, 32(4) (1989) 1239]. Being physically based, the Model was used to investigate the dependence of surface runoff pollution and its extent on the system hydrological parameters. A key factor on the availability of soil chemicals to pollute the overland flow is their displacement by infiltrating water prior to runoff initiation. Being dependent on soil moisture prior to rainfall initiation and on rainfall intensity, a lower chemical concentration and a lower load in surface runoff are obtained for longer ponding times, ones that are associated with lower rainfall rates and initially drier soil profiles. During the surface runoff flow, the chemical concentration in overland flow at the slope outlet is affected by the contact time of an overland flow parcel with the soil surface. Thus, it increases for higher values of equilibrium time — tE, lower rainfall rates, slope gradients, and higher soil-surface roughness coefficients. These parameters have an inverse effect on the surface runoff concentration by affecting the transfer coefficient of soil chemical to overland flow. A different insight into the relationship between the relevant dynamic processes throughout the storm event is achieved by studying the transient variation of soil chemical flux to overland flow, the chemical flux at the slope outlet, and the change of chemical mass in the overland flow.

Shijun Huang - One of the best experts on this subject based on the ideXlab platform.

  • A Comprehensive Mathematical Model for estimating oil drainage rate in SAGD process considering wellbore/formation coupling effect
    Heat and Mass Transfer, 2017
    Co-Authors: Linsong Cheng, Hao Gu, Shijun Huang
    Abstract:

    The aim of this work is to present a Comprehensive Mathematical Model for estimating oil drainage rate in Steam-assisted gravity drainage (SAGD) process, more importantly, wellbore/formation coupling effect is considered. Firstly, mass and heat transfer in vertical and horizontal wellbores are described briefly. Then, a function of steam chamber height is introduced and the expressions for oil drainage rate in rising and expanding steam chamber stages are derived in detail. Next, a calculation flowchart is provided and an example is given to introduce how to use the proposed method. Finally, after the Mathematical Model is validated, the effects of wellhead steam injection rate on simulated results are further analyzed. The results indicate that heat injection power per meter reduces gradually along the horizontal wellbore, which affects both steam chamber height and oil drainage rate in the SAGD process. In addition, when production time is the same, the calculated oil drainage rate from the new method is lower than that from Butler’s method. Moreover, the paper shows that when wellhead steam injection rate is low enough, the steam chamber is not formed at the horizontal well’s toe position and enhancing the wellhead steam injection rate can increase the oil drainage rate.

  • a Comprehensive Mathematical Model for estimating oil drainage rate in sagd process considering wellbore formation coupling effect
    Heat and Mass Transfer, 2017
    Co-Authors: Linsong Cheng, Hao Gu, Shijun Huang
    Abstract:

    The aim of this work is to present a Comprehensive Mathematical Model for estimating oil drainage rate in Steam-assisted gravity drainage (SAGD) process, more importantly, wellbore/formation coupling effect is considered. Firstly, mass and heat transfer in vertical and horizontal wellbores are described briefly. Then, a function of steam chamber height is introduced and the expressions for oil drainage rate in rising and expanding steam chamber stages are derived in detail. Next, a calculation flowchart is provided and an example is given to introduce how to use the proposed method. Finally, after the Mathematical Model is validated, the effects of wellhead steam injection rate on simulated results are further analyzed. The results indicate that heat injection power per meter reduces gradually along the horizontal wellbore, which affects both steam chamber height and oil drainage rate in the SAGD process. In addition, when production time is the same, the calculated oil drainage rate from the new method is lower than that from Butler’s method. Moreover, the paper shows that when wellhead steam injection rate is low enough, the steam chamber is not formed at the horizontal well’s toe position and enhancing the wellhead steam injection rate can increase the oil drainage rate.

Philipp Rostalski - One of the best experts on this subject based on the ideXlab platform.

  • A Comprehensive Mathematical Model of Motor Unit Pool Organization, Surface Electromyography, and Force Generation.
    Frontiers in physiology, 2019
    Co-Authors: Eike Petersen, Philipp Rostalski
    Abstract:

    Neuromuscular physiology is a vibrant research field that has recently seen exciting advances. Previous publications have focused on thorough analyses of particular aspects of neuromuscular physiology, yet an integration of the various novel findings into a single, Comprehensive Model is missing. In this article, we provide a unified description of a Comprehensive Mathematical Model of surface electromyographic (EMG) measurements and the corresponding force signal in skeletal muscles, both consolidating and extending the results of previous studies regarding various components of the neuromuscular system. The Model comprises motor unit (MU) pool organization, recruitment and rate coding, intracellular action potential generation and the resulting EMG measurements, as well as the generated muscular force during voluntary isometric contractions. Mathematically, it consists of a large number of linear PDEs, ODEs, and various stochastic nonlinear relationships, some of which are solved analytically, others numerically. A parameterization of the electrical and mechanical components of the Model is proposed that ensures a physiologically meaningful EMG-force relation in the simulated signals, in particular taking the continuous, size-dependent distribution of MU parameters into account. Moreover, we describe a novel nonlinear transformation of the common drive Model input, which ensures that the Model force output equals the desired target force. On a physiological level, this corresponds to adjusting the rate coding Model to the force generating capabilities of the simulated muscle, while from a control theoretical point of view, this step is equivalent to an exact linearizing transformation of the controlled neuromuscular system. Finally, an alternative analytical formulation of the EMG Model is proposed, which renders the physiological meaning of the Model more clear and facilitates a Mathematical proof that muscle fibers in this Model at no point in time represent a net current source or sink. A consistent description of a complete physiological Model as presented here, including thorough justification of Model component choices, will facilitate the use of these advanced Models in future research. Results of a numerical simulation highlight the Model’s capability to reproduce many physiological effects observed in experimental measurements, and to produce realistic synthetic data that are useful for the validation of signal processing algorithms.

  • A Comprehensive Mathematical Model of Surface Electromyography and Force Generation
    2018
    Co-Authors: Eike Petersen, Philipp Rostalski
    Abstract:

    The purpose of this article is to provide a unified description of a Comprehensive Mathematical Model of surface electromyographic (EMG) measurements and the corresponding force signal in skeletal muscles. The Model comprises motor unit pool organization, recruitment and rate coding, intracellular action potential generation and the resulting EMG measurements, as well as the generated muscular force during voluntary isometric contractions. It consolidates and extends the results of several previous publications that proposed Mathematical Models for the individual Model components. A parameterization of the electrical and mechanical components of the Model is proposed that ensures a physiologically meaningful EMG-force relation in the simulated signals. Moreover, a novel nonlinear transformation of the excitation Model input is proposed, which ensures that the Model force output equals the desired target force. Finally, an alternative analytical formulation of the EMG Model is proposed, which renders the physiological meaning of the Model more clear and facilitates a Mathematical proof that muscle fibers in this Model at no point in time represent a net current source or sink. Neuromuscular physiology is a vibrant research field that has recently seen exciting advances. Many previous publications have focused on thorough analyses of particular aspects of neuromuscular physiology, yet an integration of the various novel findings into a single, Comprehensive Model is missing. A consistent description of a complete physiological Model as presented here, including thorough justification of Model component choices, will facilitate the use of these advanced Models in future research. Results of a numerical simulation highlight the Model's capability to reproduce many physiological effects observed in experimental measurements, and to produce realistic synthetic data that are useful for the validation of signal processing algorithms. The Model is based on recent advances in the understanding of muscular physiology and hence also applicable for analyzing the influence of various physiological and measurement setup parameters on the measured force and EMG signals.