scholarly journals Mathematical Modeling and Stability Analysis of a Two-Phase Biosystem

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 791
Author(s):  
Milen Borisov ◽  
Neli Dimitrova ◽  
Ivan Simeonov
Keyword(s):  
Equilibrium Points ◽  
Static Characteristics ◽  
Software Environment ◽  
Two Phase ◽  
Web Based ◽  
Proposed Model ◽  
Production Of Hydrogen ◽  
Important Input ◽  
Stirred Bioreactors ◽  
Uniformly Bounded

We propose a new mathematical model describing a biotechnological process of simultaneous production of hydrogen and methane by anaerobic digestion. The process is carried out in two connected continuously stirred bioreactors. The proposed model is developed by adapting and reducing the well known Anaerobic Digester Model No 1 (ADM1). Mathematical analysis of the model is carried out, involving existence and uniqueness of positive and uniformly bounded solutions, computation of equilibrium points, investigation of their local stability with respect to practically important input parameters. Existence of maxima of the input–output static characteristics with respect to hydrogen and methane is established. Numerical simulations using a specially elaborated web-based software environment are presented to demonstrate the dynamic behavior of the model solutions.

scholarly journals MATHEMATICAL MODELLING OF A TWO-STAGE ANAEROBIC DIGESTION PROCESS WITH HYDROGEN AND METHANE PRODUCTION USING ADM1

2020 ◽  
pp. 18-29
Author(s):  
Milen Borisov ◽  
Dencho Denchev ◽  
Ivan Simeonov
Keyword(s):  
Anaerobic Digestion ◽  
Control Variable ◽  
Static Characteristics ◽  
Input Output ◽  
Software Environment ◽  
Two Stage ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model ◽  
Production Of Hydrogen

The aim of this study is to implement a mathematical model to simulate the dynamic behaviour of a two-stage anaerobic digestion process for simultaneous production of hydrogen and methane. The process is carried out in two connected continuously stirred bioreactors. The proposed model is developed by reducing the well known IWA Anaerobic Digester Model No 1 (ADM1). In the present study the original model concept was adapted and applied to replicate a two-stage process. The proposed model involves 13 ODEs for the 1st stage and 7 ODEs for the 2nd stage. The numerical coefficient values in the model are taken from specified literature and adapted to the case of wheat straw AD. Important input-output static characteristics and existence of maxima of the input-output static characteristics concerning the biohydrogen and biomethane production in function of the control variable (dilution rate) are presented. Supposing that both bioreactors are operating nearby these maxima the optimal ratio of the working volumes was obtained. Numerical simulations using a specially elaborated web-based software environment are presented to demonstrate the dynamic behavior of the model solutions.

FEATURES OF MOLECULAR ANALYSIS AS A REAL-TIME INTERNET SERVICE

2021 ◽  
Author(s):  
М.В. ЗАХАРОВ
Keyword(s):  
Traffic Flow ◽  
Simulation Modeling ◽  
General Purpose ◽  
Service Delivery Model ◽  
State University ◽  
Network Delay ◽  
Software Environment ◽  
Internet Service ◽  
Saint Petersburg ◽  
Proposed Model

Приведен обзор особенностей применения портативныхNIR спектрометров общего назначения, используемых для анализа состава продуктов питания и лекарственных средств. Представлена модель агрегированного потока сетевого трафика от нескольких спектрометров и модель предоставления услуги, обеспечивающая снижение сетевой задержки и объема передаваемых данных. Рассмотрен метод построения сети на основе граничных вычислений для снижения сетевой задержки. Для проверки предложенной модели и метода проведено имитационное моделирование в среде AnyLogic. The Bonch-Bruevich Saint-Petersburg State University of Telecommunications The article provides an overview of the features of the use of portable general-purpose NIR spectrometers to analyze the composition of food or medicines. A model of the aggregated network traffic flow of several spectrometers and a service delivery model, which provides the reduction of network delay and amount of transmitted data, are presented. A method of constructing a network based on edge computing for reduction of network delay is considered. To verify the proposed model and method simulation modeling was carried out in the software environment AnyLogic.

Prediction of High Viscosity Liquid/Gas Two-Phase Slug Length in Horizontal and Slightly Inclined Pipelines

2021 ◽  
Author(s):  
Omar Shaaban ◽  
Eissa Al-Safran
Keyword(s):  
Numerical Optimization ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
High Viscosity ◽  
Oil Well ◽  
Liquid Slug ◽  
Two Phase ◽  
Proposed Model ◽  
Wide Range ◽  
Flow Closure

Abstract The production and transportation of high viscosity liquid/gas two-phase along petroleum production system is a challenging operation due to the lack of understanding the flow behavior and characteristics. In particular, accurate prediction of two-phase slug length in pipes is crucial to efficiently operate and safely design oil well and separation facilities. The objective of this study is to develop a mechanistic model to predict high viscosity liquid slug length in pipelines and to optimize the proper set of closure relationships required to ensure high accuracy prediction. A large high viscosity liquid slug length database is collected and presented in this study, against which the proposed model is validated and compared with other models. A mechanistic slug length model is derived based on the first principles of mass and momentum balances over a two-phase slug unit, which requires a set of closure relationships of other slug characteristics. To select the proper set of closure relationships, a numerical optimization is carried out using a large slug length dataset to minimize the prediction error. Thousands of combinations of various slug flow closure relationships were evaluated to identify the most appropriate relationships for the proposed slug length model under high viscosity slug length condition. Results show that the proposed slug length mechanistic model is applicable for a wide range of liquid viscosities and is sensitive to the selected closure relationships. Results revealed that the optimum closure relationships combination is Archibong-Eso et al. (2018) for slug frequency, Malnes (1983) for slug liquid holdup, Jeyachandra et al. (2012) for drift velocity, and Nicklin et al. (1962) for the distribution coefficient. Using the above set of closure relationships, model validation yields 37.8% absolute average percent error, outperforming all existing slug length models.

scholarly journals Analysis of Smooth Implementation of Industry Poverty Alleviation considering Government Supervision

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Haifeng Yao ◽  
Jiangyue Fu
Keyword(s):  
Equilibrium Point ◽  
Evolutionary Game Theory ◽  
Poverty Alleviation ◽  
Equilibrium Points ◽  
Evolutionary Game ◽  
Parameter Design ◽  
Game Model ◽  
Government Supervision ◽  
Proposed Model ◽  
The Government

Vigorous implementation of industrial poverty alleviation is the fundamental path and core power of poverty alleviation in impoverished areas. Enterprises and poor farmers are the main participants in industry poverty alleviation. Government supervision measures regulate their behaviors. This study investigates how to smoothly implement industry poverty alleviation projects considering government supervision. A game model is proposed based on the evolutionary game theory. It analyses the game processes between enterprises and poor farmers with and without government supervision based on the proposed model. It is shown that poverty alleviation projects will fail without government supervision given that the equilibrium point (0, 0) is the ultimate convergent point of the system but will possibly succeed with government supervision since the equilibrium points (0, 0) and (1, 1) are the ultimate convergent point of the system, where equilibrium point (1, 1) is our desired results. Different supervision modes have different effects on the game process. This study considers three supervision modes, namely, only reward mode, only penalty mode, and reward and penalty mode, and investigates the parameter design for the reward and penalty mode. The obtained results are helpful for the government to develop appropriate policies for the smooth implementation of industry poverty alleviation projects.

New Relationship Between Resistivity Index and Relative Permeability

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Dong Ma ◽  
Changwei Liu ◽  
Changhui Cheng
Keyword(s):  
Capillary Pressure ◽  
Relative Permeability ◽  
Pressure Data ◽  
Two Phase ◽  
Resistivity Index ◽  
Proposed Model ◽  
Petrophysical Parameter ◽  
Oil Water ◽  
Better Than ◽  
Good Agreement

Relative permeability as an important petrophysical parameter is often measured directly in the laboratory or obtained indirectly from the capillary pressure data. However, the literature on relationship between relative permeability and resistivity is lacking. To this end, a new model of inferring two-phase relative permeability from resistivity index data was derived on the basis of Poiseuille's law and Darcy's law. The wetting phase tortuosity ratio was included in the proposed model. The relative permeabilities computed from the capillary pressure data, as well as the experimental data measured in gas–water and oil–water flow condition, were compared with the proposed model. Both results demonstrated that the two-phase permeability obtained by proposed model were generally in good agreement with the data computed from capillary pressure and measured in the laboratory. The comparison also showed that our model was much better than Li model at matching the relative permeability data.

A fuzzy goal programming approach for selecting sustainable suppliers

2017 ◽  
Vol 24 (5) ◽  
pp. 1138-1165 ◽  
Author(s):  
Peeyush Pandey ◽  
Bhavin J. Shah ◽  
Hasmukh Gajjar
Keyword(s):  
Goal Programming ◽  
Supplier Selection ◽  
Qualitative Data ◽  
Fuzzy Goal Programming ◽  
Programming Approach ◽  
Two Phase ◽  
Content Type ◽  
Lean Practices ◽  
Proposed Model ◽  
Fuzzy Goal

Purpose Due to the ever increasing concern toward sustainability, suppliers nowadays are evaluated on the basis of environmental performances. The data on supplier’s performance are not always available in quantitative form and evaluating supplier on the basis of qualitative data is a challenging task. The purpose of this paper is to develop a framework for the selection of suppliers by evaluating them on the basis of both quantitative and qualitative data. Design/methodology/approach Literature on sustainability, green supply chain and lean practices related to supplier selection is critically reviewed. Based on this, a two phase fuzzy goal programming approach integrating hyperbolic membership function is proposed to solve the complex supplier selection problem. Findings Results obtained through the proposed approach are compared to the traditional models (Jadidi et al., 2014; Ozkok and Tiryaki, 2011; Zimmermann, 1978) of supplier selection and were found to be optimal as it achieves higher aspiration level. Practical implications The proposed model is adaptive to solve real world problems of supplier selection as all criteria do not possess the same weights, so the managers can change the criteria and their weights according to their requirement. Originality/value This paper provides the decision makers a robust framework to evaluate and select sustainable supplier based on both quantitative and qualitative data. The results obtained through the proposed model achieve greater satisfaction level as compared to those achieved by traditional methods.

Mechanisms of Gas Turbine Regenerator Fouling

1967 ◽  
Author(s):  
James A. Miller
Keyword(s):  
Heat Transfer ◽  
Particulate Matter ◽  
Theoretical Model ◽  
Gas Turbine ◽  
Two Phase ◽  
Degradation Data ◽  
Proposed Model ◽  
Controlling Mechanism ◽  
Adhesive Coating ◽  
Phase Process

Possible mechanisms of gas turbine regenerator fouling are examined and compared with extant experimental evidence. A theoretical model of fouling which encompasses a two-phase process is proposed. It is shown that the controlling mechanism is the condensation of heavy hydrocarbon isomers which form an adhesive coating in which particulate matter subsequently become entrapped. Typical overall heat transfer and pressure drop degradation data are presented which tend to support the proposed model.

A Linear Stability Analysis for an Improved One-Dimensional Two-Fluid Model

2003 ◽  
Vol 125 (2) ◽  
pp. 387-389 ◽  
Author(s):  
Jin Ho Song
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Fluid Model ◽  
Two Phase ◽  
One Dimensional ◽  
Proposed Model ◽  
Two Fluid Model ◽  
The One ◽  
Two Fluid

A linear stability analysis is performed for a two-phase flow in a channel to demonstrate the feasibility of using momentum flux parameters to improve the one-dimensional two-fluid model. It is shown that the proposed model is stable within a practical range of pressure and void fraction for a bubbly and a slug flow.

Mathematical Modeling and Stability Analysis of Japanese Encephalitis

2020 ◽  
Vol 12 (1) ◽  
pp. 120-127
Author(s):  
Vinod Baniya ◽  
Ram Keval
Keyword(s):  
Mathematical Modeling ◽  
Japanese Encephalitis ◽  
Disease Transmission ◽  
Equilibrium Points ◽  
Numerical Verification ◽  
Transmission Potential ◽  
Dynamical Behaviors ◽  
Proposed Model ◽  
The Stability ◽  
Stability Issues

Mathematical modeling of Japanese encephalitis (JE) disease in human population with pig and mosquito has been presented in this paper. The proposed model, which involves three compartments of human (Susceptible, Vaccinated, Infected), two compartments of mosquito (Susceptible, Infected) and three compartments of the pig (Susceptible, Vaccinated, Infected). In this work, it is assumed that JE spreads between susceptible class and infected mosquitoes only. Basic results like boundedness of the model, the existence of equilibrium and local stability issues are investigated. Here, to measure the disease transmission potential in the population the basic reproduction number (R0) from the system has been analyzed w.r.t. control parameters both numerically and theoretically. The dynamical behaviors of the system have been analyzed by using the stability theory of differential equations and numerical simulations at equilibrium points. A numerical verification of results is carried out of the model under consideration.

A HIERARCHICAL MODEL FOR MULTI-PHASE FRACTAL MEDIA

Fractals ◽  
2010 ◽  
Vol 18 (01) ◽  
pp. 53-64 ◽  
Author(s):  
MAOFEI MEI ◽  
BOMING YU ◽  
JIANCHAO CAI ◽  
LIANG LUO
Keyword(s):  
Distribution Function ◽  
Pore Space ◽  
Fractal Dimensions ◽  
Solid Particles ◽  
Two Phase ◽  
Fractal Media ◽  
Proposed Model ◽  
Three Phase ◽  
Multi Phase ◽  
Good Agreement

The size distributions of solid particles and pores in porous media are approximately hierarchical and statistically fractals. In this paper, a model for single-phase fractal media is constructed, and the analytical expressions for area, fractal dimension and distribution function for solid particles are derived. The distribution function of solid particles obtained from the proposed model is in good agreement with available experimental data. Then, a model for approximate two-phase fractal media is developed. Good agreement is found between the predicted fractal dimensions for pore space from the two-phase fractal medium model and the existing measured data. A model for approximate three-phase fractal media is also presented by extending the obtained two-phase model.

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