A Scheme for Measuring Kinetic Coefficients

1978 ◽  
pp. 125-143
Author(s):  
N. G. Basov
Keyword(s):  
Kinetic Coefficients

Theory of the kinetic coefficients of the atomically rough surface of 4He crystals

1983 ◽  
Vol 44 (6) ◽  
pp. 723-736 ◽  
Author(s):  
R.M. Bowley ◽  
D.O. Edwards
Keyword(s):  
Rough Surface ◽  
Kinetic Coefficients

scholarly journals Asymmetric and chaotic responses of dry friction oscillators with different static and kinetic coefficients of friction

Meccanica ◽  
2021 ◽  
Author(s):  
Gábor Csernák ◽  
Gábor Licskó
Keyword(s):  
Dry Friction ◽  
Continuation Method ◽  
Friction Model ◽  
Lugre Friction Model ◽  
Kinetic Coefficients ◽  
Friction Oscillator ◽  
Lugre Friction ◽  
Friction Parameters ◽  
Two Parameter ◽  
Parameter Bifurcation

AbstractThe responses of a simple harmonically excited dry friction oscillator are analysed in the case when the coefficients of static and kinetic coefficients of friction are different. One- and two-parameter bifurcation curves are determined at suitable parameters by continuation method and the largest Lyapunov exponents of the obtained solutions are estimated. It is shown that chaotic solutions can occur in broad parameter domains—even at realistic friction parameters—that are tightly enclosed by well-defined two-parameter bifurcation curves. The performed analysis also reveals that chaotic trajectories are bifurcating from special asymmetric solutions. To check the robustness of the qualitative results, characteristic bifurcation branches of two slightly modified oscillators are also determined: one with a higher harmonic in the excitation, and another one where Coulomb friction is exchanged by a corresponding LuGre friction model. The qualitative agreement of the diagrams supports the validity of the results.

scholarly journals Comparison of Biocompatible Coatings Produced by Plasma Electrolytic Oxidation on cp-Ti and Ti-Zr-Nb Superelastic Alloy

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 401
Author(s):  
Ruzil Farrakhov ◽  
Olga Melnichuk ◽  
Evgeny Parfenov ◽  
Veta Mukaeva ◽  
Arseniy Raab ◽  
...  
Keyword(s):  
Plasma Electrolytic Oxidation ◽  
Electrochemical Impedance ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
X Ray ◽  
Kinetic Coefficients ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Cp Ti ◽  
Peo Coatings

The paper compares the coatings produced by plasma electrolytic oxidation (PEO) on commercially pure titanium and a novel superelastic alloy Ti-18Zr-15Nb (at. %) for implant applications. The PEO coatings were produced on both alloys in the identical pulsed bipolar regime. The properties of the coatings were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The PEO process kinetics was modeled based on the Avrami theorem and Cottrell equation using a relaxation method. The resultant coatings contain TiO2, for both alloys, and NbO2, Nb2O5, ZrO2 for Ti-18Zr-15Nb alloy. The coating on the Ti-18Zr-15Nb alloy has a higher thickness, porosity, and roughness compared to that on cp-Ti. The values of the kinetic coefficients of the PEO process—higher diffusion coefficient and lower time constant for the processing of Ti-18Zr-15Nb—explain this effect. According to the electrochemical studies, PEO coatings on Ti-18Zr-15Nb alloy provide better corrosion protection. Higher corrosion resistance, porosity, and roughness contribute to better biocompatibility of the PEO coating on Ti-18Zr-15Nb alloy compared to cp-Ti.

Effect of partial ordering of a two-dimensional system of scatterers on the anisotropy of its kinetic coefficients

1998 ◽  
Vol 32 (10) ◽  
pp. 1116-1118
Author(s):  
N. S. Averkiev ◽  
A. M. Monakhov ◽  
A. Yu. Shik ◽  
P. M. Koenraad
Keyword(s):  
Partial Ordering ◽  
Dimensional System ◽  
Two Dimensional ◽  
Kinetic Coefficients ◽  
Two Dimensional System

scholarly journals Design of Cell-Based Flotation Circuits under Uncertainty: A Techno-Economic Stochastic Optimization

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 459
Author(s):  
Seyed Hassan Amini ◽  
Aaron Noble
Keyword(s):  
Circuit Design ◽  
Net Present Value ◽  
Structure Identification ◽  
Optimal Size ◽  
Flotation Kinetics ◽  
Deterministic Models ◽  
Kinetic Coefficients ◽  
Study Results ◽  
Circuit Structure ◽  
The Impact

The design of cell-based flotation circuits is often completed in two distinct phases, namely circuit structure identification and equipment sizing selection. While recent literature studies have begun to address the implications of stochastic analysis, industrial practice in flotation circuit design still strongly favors the use of deterministic metallurgical modeling approaches. Due to the complexity of the available mathematical models, most flotation circuit design techniques are constructed based on deterministic models. Neglecting the impact of various sources of uncertainty may result in the identification of circuit solutions that are only optimal in a narrow region of specific operating scenarios. One promising strategy to address this shortcoming is through the Sample Average Approximation (SAA) methodology, a stochastic approach to handling uncertainty that has been widely applied in other disciplines such as supply chain and facility location management problems. In this study, a techno-economic optimization algorithm was formulated to select the optimal size and number of flotation cells for a fixed circuit structure while considering potential uncertainty in several input parameter including feed grade, kinetic coefficients, and metal price. Initially, a sensitivity analysis was conducted to screen the uncertain parameters. After simplifying the optimization problem, the SAA approach was implemented to determine the equipment configuration (i.e., cell size and number) that maximizes the plant’s net present value while considering the range of potential input values due to parameter uncertainty. The SAA methodology was found to be useful in analyzing uncertainty in flotation kinetics; however, the approach did not provide a useful means to assess the influence of uncertainties in ore grade and metal price, as these values are not significant in determining equipment size but rather influence the optimal circuit structure, which was not considered in this study. Results from an application example indicate that the SAA approach produces optimal solutions not initially identified in a deterministic optimization, and these SAA solutions tend to provide greater robustness to uncertainty and variation in the flotation kinetics.

Research of drying kinetics of prepared wheat flour

2021 ◽  
Vol 9 (16) ◽  
pp. 212-220
Author(s):  
Liubomyr Khomichak ◽  
◽  
Inha Kuznietsova ◽  
Svetlana Vysotska ◽  
Sergiy Tkachenko ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wheat Flour ◽  
Raw Materials ◽  
Control Sample ◽  
Raw Material ◽  
Convective Drying ◽  
Kinetic Dependence ◽  
Vital Functions ◽  
Kinetic Coefficients ◽  
Kinetics Of

Introduction. Processing of grain raw material with influence on starch or albumens by application of heat treatment creates the variety of functional properties of a product and is perspective in the modern terms vital functions of man. Research methods and methods. The flour obtained from wheat of the Ascanian wheat and from wheat of the soft varieties: Sophia ("sweet wheat"), Blond (soft) and Chornobrova (enriched with micro- and macronutrients) were used in the study. Thermal modification of flour samples was carried out in a convective manner. The control sample for determining the quality indicators is obtained in industrial conditions, extruded wheat flour produced by LLC "AS groups, LTD". Research results. The obtained kinetic dependence shows the gradual loss of moisture standards with different speed which accordingly influences on duration of drying. The moisture content of the drying agent most affects the intensity at the initial stage of the constant drying rate. With an increase in the moisture content of the coolant, the period of constant drying increases and the amount of evaporated moisture increases during this period. With the subsequent removal of moisture from raw materials, the degree of influence of this parameter on the intensity decreases. The nature of the drying curves is the same and the recommended process for obtaining modified flour is the process duration of 300 minutes or 5 hours. It was determined microscopically, that the samples of dried wheat flour have a purpose and are partially destroyed by starch granules and amorphization of biocomposite materials. Based on the data on the kinetics of drying flour samples, the kinetic coefficients and values of the critical moisture content for drying wheat flour were calculated, which is 1.18-1.30 %. It was determined that for the sensorial indicators the obtained samples have indicators characteristic of the varietal characteristics of wheat, from which the flour was taken. In terms of physical and chemical parameters, the modified wheat flour samples are not inferior to the well-known industrial sample of extruded flour. Conclusions. Use of flour, obtained from the wheat with different correlation of amilose and amylopectin, positively influences on a technological process and allows to extend the assortment of modified starch products, and accordingly, food products. Kinetics of the convective drying standards of the flour is investigated. Researches showed that a it is physically modified flour obtained from the different sorts of the soft wheat is not inferior in quality to the extruded wheat flour.

Model Calibration for the High-Purity Oxygen Activated Sludge Process – Algorithm Development and Evaluation

1993 ◽  
Vol 28 (11-12) ◽  
pp. 163-171 ◽  
Author(s):  
Weibo (Weber) Yuan ◽  
David Okrent ◽  
Michael K. Stenstrom
Keyword(s):  
Activated Sludge ◽  
High Purity ◽  
Model Calibration ◽  
Process Model ◽  
Model Parameters ◽  
Complex Method ◽  
Activated Sludge Process ◽  
Activated Sludge Model ◽  
Kinetic Coefficients ◽  
Calibration Algorithm

A model calibration algorithm is developed for the high-purity oxygen activated sludge process (HPO-ASP). The algorithm is evaluated under different conditions to determine the effect of the following factors on the performance of the algorithm: data quality, number of observations, and number of parameters to be estimated. The process model used in this investigation is the first HPO-ASP model based upon the IAWQ (formerly IAWPRC) Activated Sludge Model No. 1. The objective function is formulated as a relative least-squares function and the non-linear, constrained minimization problem is solved by the Complex method. The stoichiometric and kinetic coefficients of the IAWQ activated sludge model are the parameters focused on in this investigation. Observations used are generated numerically but are made close to the observations from a full-scale high-purity oxygen treatment plant. The calibration algorithm is capable of correctly estimating model parameters even if the observations are severely noise-corrupted. The accuracy of estimation deteriorates gradually with the increase of observation errors. The accuracy of calibration improves when the number of observations (n) increases, but the improvement becomes insignificant when n>96. It is also found that there exists an optimal number of parameters that can be rigorously estimated from a given set of information/data. A sensitivity analysis is conducted to determine what parameters to estimate and to evaluate the potential benefits resulted from collecting additional measurements.

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