Ion Transfer Model Research Articles

Stabilization Analysis and Impulsive Controller Design for Positive Interval Type-2 Polynomial Fuzzy Systems

This article investigates the polynomial fuzzy impulsive control problem for positive nonlinear systems subject to parameter uncertainties. The positive nonlinear systems are represented as positive interval type-2 (IT2) polynomial fuzzy-model-based systems, while the parameter uncertainties are captured by the IT2 membership functions (MFs). Considering that the controller being designed needs to be implementable and practical, in addition to ensuring the positivity and stability of the system, there are still some potential requirements for the controller, such as lower implementation cost and control cost. To reduce the implementation cost, the IT2 polynomial fuzzy impulsive controller is designed under the imperfect premise matching concept that the premise MFs and the number of rules of fuzzy controller are different from those of fuzzy model. To reduce the control cost, the impulsive controller that can tolerate larger impulse control interval (ICI) is designed by the following two novel methods. The first one is the proposed impulse-time-dependent discretized polynomial copositive Lyapunov function whose Lyapunov variable is designed as the interpolation polynomial function of time. The second one is the advanced IT2 membership-function-dependent (IT2MFD) analysis method which is improved by a novel footprint of uncertainty partitioning method proposed by this paper, so that this advanced IT2MFD method can alleviate the negative impact of parameter uncertainties on the ICI. Finally, a simulation example using lipoprotein metabolism and potassium ion transfer model as the nonlinear system to be controlled is used to verify the effectiveness of the proposed impulsive control methods.

Stabilization of Positive Systems With Time Delay via the Takagi-Sugeno Fuzzy Impulsive Control.

In this study, the Takagi-Sugeno (T-S) fuzzy impulsive control problem is investigated for a class of nonlinear positive systems with time delay. The time delay under consideration is both in the continuous-time dynamics and at the impulsive instants, which can model practical systems more accurately. An impulse-time-dependent copositive Lyapunov function (IDCLF) is constructed, and the Razumikhin technique is adopted to develop conditions that ensure the globally exponential stability of T-S fuzzy positive systems with delayed impulses. The size constraint between the impulse delay and the bound of impulsive intervals is removed. A T-S fuzzy impulsive controller is designed in terms of the solutions to certain vector inequalities that are readily solvable. Numerical examples and a practical example of lipoprotein metabolism and potassium ion transfer model are given to demonstrate the effectiveness, advantages, and practicality of the proposed results.

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Based on the electrophysical and structural data, a crystallophysical model of ion transfer in superionic conductors Ba1-xLaxF2 + x and Ca1-xYxF2 + x (space group Fm3m) is proposed, in which the charge carriers are mobile interstitial ions Fmob-, formed as a result of heterovalent substitutions of fluorite fragments [M14F64] (M = Ca, Ba) into structural clusters [M8R6F69] (R = La, Y). Single crystals of solid solutions Ca1-xYxF2 + x (0.02≤ x≤0.16) and Ba1-xLaxF2 + x (x = 0.31) were obtained by directional crystallization of the melt. The mobilities of ionic carriers in isostructural superionics Ba0.69La0.31F2.31, Ca0.84Y0.16F2.16, Pb0.67Cd0.33F2, and Pb0.9Sc0.1F2.1 are compared. Crystals Ba1-xLaxF2 + x and Ca1-xYxF2 + x with improved conductometric and mechanical characteristics are promising for replacing the traditional CaF2 electrolyte in galvanic cells for thermodynamic research of chemicals.

Mobility of Charge Carriers in a Single Crystal and Nanoceramic of the Superionic Pb1 – xSnxF2 Conductor (x = 0.2)

A crystallophysical model of ion transfer in the superionic Pb1 – xSnxF2 conductor with a fluorite (CaF2) structure is proposed. The concentration dependence of the ionic conductivity of Pb1 – xSnxF2 single crystals and poly- and nanocrystals is analyzed. The single-crystal form of the superionic conductor is characterized by the highest conductivity. The mobility and concentration of anionic charge carriers in a single crystal and ceramics of Pb1 – xSnxF2 (x = 0.2) is calculated on the basis of structural and electrophysical data. The mobility of carriers μmob = 2.5 × 10–6 cm2/s V (at 293 K) in a single crystal is seven times higher than in nanoceramic. The concentration of carriers nmob = 1.7 × 1021 and 3.6 × 1021 cm3 (4.5 and 9.5% of the total number of anions) for a single crystal and nanoceramic, respectively. The comparison of isostructural Pb0.8Sn0.2F2, Pb0.67Cd0.33F2, and Pb0.9Sc0.1F2.1 single crystals shows that anionic carriers have a maximum mobility in the β-PbF2 and SnF2 based solid solution.

Higher capacity utilization and rate performance of lead acid battery electrodes using graphene additives

Abstract Graphene nano-sheets such as graphene oxide, chemically converted graphene and pristine graphene improve the capacity utilization of the positive active material of the lead acid battery. At 0.2C, graphene oxide in positive active material produces the best capacity (41% increase over the control), and improves the high-rate performance due to higher reactivity at the graphene/active material interface. The in-situ changes in the graphene structure and oxygen states support these, as well as higher adsorptive surface area, better graphene/lead dioxide interfacial reaction, and finer & highly utilized lead dioxide phases. The multi-scale physio-chemical mechanisms improving capacity and cycle life is thus: Electrolyte/ionic permeation improvements results from increase in pre-formation porosity, and higher interfacial reactivity at gel zone which enhances active material reversibility. Our ion transfer model reveals the optimized redox reaction in the electro-active zone of graphene enhanced active materials. This work shows the best enhancement in the capacity of lead-acid battery positive electrode till date.

Higher Capacity Utilization and Rate Performance of Lead Acid Battery Electrodes Using Graphene Additives

Graphene nano-sheets such as graphene oxide, chemically converted graphene and pristine graphene [1-8] improve the capacity utilization of the positive active material of the lead acid battery. At 0.2C, graphene oxide in positive active material produces the best capacity (41% increase over the control), and improves the high-rate performance due to the higher reactivity at the graphene/active material interface. The in-situ changes in the graphene structure and oxygen states [1-2] support these, as well as higher adsorptive surface area, better graphene/lead dioxide interfacial reaction, and finer & highly utilized lead dioxide phases. The multi-scale physio-chemical mechanisms improving capacity and cycle life is thus: Electrolyte/ionic permeation improvements results from increase in pre-formation porosity, and higher interfacial reactivity at gel zone which enhances active material reversibility. Our ion transfer model reveals the optimized redox reaction in the electro-active zone of graphene-enhanced active materials. This work shows the best enhancement in the capacity of lead-acid battery positive electrode till date.

Подвижность носителей заряда в монокристалле и нанокерамике суперионного проводника Pb-=SUB=-1-x-=/SUB=-Sn-=SUB=-x-=/SUB=-F-=SUB=-2-=/SUB=- (x=0.2)

AbstractA crystallophysical model of ion transfer in the superionic Pb_1 – _ x Sn_ x F_2 conductor with a fluorite (CaF_2) structure is proposed. The concentration dependence of the ionic conductivity of Pb_1 – _ x Sn_ x F_2 single crystals and poly- and nanocrystals is analyzed. The single-crystal form of the superionic conductor is characterized by the highest conductivity. The mobility and concentration of anionic charge carriers in a single crystal and ceramics of Pb_1 – _ x Sn_ x F_2 ( x = 0.2) is calculated on the basis of structural and electrophysical data. The mobility of carriers μ_mob = 2.5 × 10^–6 cm^2/s V (at 293 K) in a single crystal is seven times higher than in nanoceramic. The concentration of carriers n _mob = 1.7 × 10^21 and 3.6 × 10^21 cm^3 (4.5 and 9.5% of the total number of anions) for a single crystal and nanoceramic, respectively. The comparison of isostructural Pb_0.8Sn_0.2F_2, Pb_0.67Cd_0.33F_2, and Pb_0.9Sc_0.1F_2.1 single crystals shows that anionic carriers have a maximum mobility in the β-PbF_2 and SnF_2 based solid solution.

Stationary model of salt ion transfer in two-dimensional electrodialysis desalting channel in galvanostatic mode

Introduction. The theoretical description of the ion transport in membrane systems in the galvanostatic mode is presented. A desalting channel of the electrodialysis apparatus is considered as a membrane system. The work objectives are the development and verification of a two-dimensional mathematical model of the stationary transport of salt ions in the desalting channel of the electrodialysis apparatus for the galvanostatic mode.Materials and Methods. A new model of ion transfer is proposed. It is based on the Nernst –Planck – Poisson equations for the electric potential and on the equation for the electric current stream function. A numerical solution to the boundary value model problem by the finite element method is obtained using the Comsol Multiphysics software package.Research Results. The developed mathematical model enables to describe the stationary transfer of binary salt ions in the desalting channel of the electrodialysis apparatus. Herewith, the violation of the solution electroneutrality and the formation of the dilated domain of space charge at overlimiting currents in the galvanostatic mode are considered. A good agreement between the physicochemical characteristics of the transfer calculated by the models for the galvanostatic and potentiostatic modes implies adequacy of the constructed model.Discussion and Conclusions. The developed model can interpret the experimental study results of ion transfer in membrane systems if this process takes place in the galvanostatic mode. Some electrokinetic processes are associated with the appearance of a dilated domain of space charge at overlimiting currents. When describing the formation of this domain, it is possible to find out how the processes dependent on it affect the ion transfer in the galvanostatic mode.

Numerical study of CaCO3 scaling in submerged vacuum membrane distillation and crystallization (VMDC)

The kinetics of CaCO3 scaling in a submerged vacuum membrane distillation and crystallization (VMDC) operation was evaluated using numerical methods incorporating the “mass jump” method to evaluate the temperature and concentration on the membrane surface, with experimental validation. As the concentration at the membrane surface was higher than the bulk feed solution, a scaling model based on the surface integration model was more accurate than the ion transfer model, with the energy activation (Ea) of 89.2 kJ/mol and zero order rate constant (k0) of 5.81 × 108 m4/kg·s. The CaCO3 deposition rate was significantly affected by temperature polarization and concentration polarization, indicated by 40% increase and 23% decrease on CaCO3 deposition rate when assuming no temperature polarization and concentration polarization, respectively. However, competing effects of temperature polarization and concentration polarization resulted in only an 8% increase of the CaCO3 deposition rate when both were neglected. Investigation of CaCO3 scale accumulation over 20 h in solution conducive to bulk precipitation (0.35 g/L CaCl2 and 0.73 g/L NaHCO3) and solutions below bulk precipitation threshold (0.0875 g/L CaCl2 and 0.1825 g/L NaHCO3) resulted in 9–11% higher CaCO3 accumulation when both temperature polarization and concentration polarization were neglected in the calculation. This can be a concern in prediction of CaCO3 scaling on longer operation time test. The model development method and implementation of this study can be adapted to provide guidance in study of MD process for high saline water treatment with inevitable scaling.

Concentration Distribution of Chloride Ion under the Influence of the Convection-Diffusion Coupling

The transfer process of chloride ion under the action of the convection-diffusion coupling was analyzed in order to predict the corrosion of reinforcement and the durability of structure more accurately. Considering the time-varying properties of diffusion coefficient and the space-time effect of the convection velocity, the differential equation for chloride ion transfer under the action of the convection-diffusion coupling was constructed. And then the chloride ion transfer model was validated by the existing experimental datum and the actual project datum. The results showed that when only diffusion was considered, the chlorine ion concentration increased with the time and decreased with the decay index of time. Under the action of the convection-diffusion coupling, at each point of coupling region, the chloride ion concentration first increased and then decreased and tended to stabilize, and the maximum appeared at the moment of convection velocity being 0; in the diffusion zone, the chloride ion concentration increased over time, and the chloride ion concentration of the same location increased with the depth of convection (in the later period), the velocity of convection (in the early period), and the chloride ion concentration of the surface.

Migration of inorganic ions from the leachate of the Rio das Ostras landfill: A comparison of three different configurations of protective barriers

Batch tests and diffusion tests were performed to analyze the efficiency of a protective barrier in a landfill consisting of compacted soil with 10% bentonite compared to the results obtained for only compacted soil and for compacted soil covered with a 1-mm-thick HDPE geomembrane; the soil and leachate were collected from the Rio das Ostras Landfill in Rio de Janeiro, Brazil. The diffusion tests were performed for periods of 3, 10 and 60days. After the test period, the soil pore water was analyzed and the profiles for chloride, potassium and ammonium were determined along a 6-cm soil depth. The results of the batch tests performed to define sorption parameters were used to adjust the profiles obtained in the diffusion cell experiment by applying an ion transfer model between the interstitial solution and the soil particles. The MPHMTP model (Multi Phase Heat and Mass Transfer Program), which is based upon the solution of the transport equations of the ionic contaminants, was used to solve the inverse problem of simultaneously determining the effective diffusion coefficients. The results of the experimental tests and of the model simulation confirmed that the compacted soil with 10% bentonite was moderately efficient in the retention of chloride, potassium and ammonium ions compared to the configurations of compacted soil with a geomembrane and compacted soil alone, representing a solution that is technically feasible and requires potentially lower costs for implementation in landfills.

“Flow of Electrolytes in a Porous Medium”

A two-scale model of ion transfer in a porous medium is obtained for one-dimensional horizontal flows under the action of a pressure gradient and an external electric field by the method of homogenization. Steady equations of electroosmotic flows in flat horizontal nano-sized slits separated by thin dielectric partitions are averaged over a small-scale variable. The resultant macroequations include Poisson’s equation for the vertical component of the electric field and Onsager’s relations between flows and forces. The total horizontal flow rate of the fluid is found to depend linearly on the pressure gradient and external electric field, and the coefficients in this linear relation are calculated with the use of microequations.

Estimated error of potential difference measurement with the Luggin capillaries by using a 2D mathematical model of ion transfer

Estimated error of potential difference measurement with the Luggin capillaries by using a 2D mathematical model of ion transfer

A cake-washing model with an overall cation transfer in kraft pulp washing

Cake washing of freely mobile ions was described by an advection–dispersion equation combined with the Donnan equilibrium and an overall ion transfer model between the external liquid phase and the fiber phase of kraft pulp. The ion exchange rate coefficients between the phases were determined from the earlier published leaching test results for an oxygen delignified Scandinavian hardwood kraft pulp. The time constant of the first order process model was about 19 s for calcium and manganese and about 6 s for sodium and magnesium. The calculated results for various elements during the acid displacement were compared with the published displacement experiments. Calculated concentrations and pH profiles in wash effluent and cake were shown. Moreover, changes in pH values and redistribution of ions between the external phase and the fiber phase in the cake during the acid displacement were also demonstrated.

Mixed ion transfer in redox processes of poly(3,4-ethylenedioxythiophene)

A model considering the transfer of counter ions and solvent molecules has been presented to explain the complicated ion transfer in polymer films during electrochemical redox processes. The developed mixed ion transfer model is used to analyze the ion transfer behavior of poly(3,4-ethylenedioxythiophene) during doping and dedoping processes. The results indicate that both anions and cations are involved in n-doping as well as in p-doping processes. The behavior of different electrolyte ions is also studied. The developed model shows that solvent molecules are also transferred in conjunction with the ion transfer.

Unified carrier-channel model of ion transfer across lipid bilayer membranes

Unified carrier-channel model of ion transfer across lipid bilayer membranes

Specific features of the formation of oxygen defects in the SrFeO2.5 ferrate with a brownmillerite structure

The electronic structure and chemical bonding in the Sr2Fe2O5 strontium ferrate are investigated in the framework of the ab initio linear-muffin-tin-orbital tight-binding representation and extended Hukcel calculations. Models of defect formation (oxygen vacancies and anti-Frenkel defects) in the brownmillerite structure are considered. A model of ion transfer in strontium ferrate is proposed reasoning from the results of the calculations.

Mechanism and dynamics of methyl and ethyl orange transfer across the water/1,2-dichloroethane interface

The mechanism of methyl (MO) and ethyl orange (EO) transfer across the water/1,2-dichloroethane (DCE) interface was studied from thermodynamic and kinetic points of view. Ionic partition diagrams were constructed from the appropriate acid/base equilibrium and formal transfer potentials. In situ spectroscopic studies suggest that the transfer of the anionic species from water to DCE takes place mainly via the non-hydrogen bonded form. On the other hand, the transfer of the anions from DCE to water with a pH smaller than the p K a involves the protonation of MO during the transfer step. The rate of ion transfer was studied by chronoabsorptometry and potential modulated reflectance. It was confirmed that the transfer of both anions is a potential dependent process, giving a standard apparent rate constant of the order of 10 −2 cm s −1 and a transfer coefficient of 0.5. Kinetic data are discussed within the framework of existing model for ion transfer at ITIES. Theoretical aspects of chronoabsorptometry for the study of ion transfer kinetics are also outlined.

Contact Electrification of Materials: The Chemistry of Ions on Polymer Surfaces

This report summarizes some recent studies aimed at determining the role of ion transfer in contact charging in polymers. The studies were carried out using blends of polymers and ionomers or polymers and organic salts. These blends were charged by contacting with a metal surface and the contact charge which developed was related to the amount and structure of the ions in the polymer blend. A Kelvin Probe and an atomic Force Microbalance were used to determine the charge. A ion transfer model for contact charging was developed which relates the charge to the ions which are on the surface and are mobile, i.e. not covalently bonded or ion pair associated.

A model for ion transfer through liquid|liquid interfaces

Using a lattice-gas model we calculate the potential of mean force experienced by a single ion in the vicinity of a liquid|liquid interface. Typically, this potential exhibits both a maximum and a minimum; ion transfer is therefore an activated process involving the transfer over a barrier. An explicit expression for the rate constant is derived. Model calculations show that in most situations the reaction will follow a Butler-Volmer type law. Double layer corrections are shown to be inappropriate.