Computer Simulation and Experimental Studies of Various Environmental Gases (NH3, CH2O, SO2, H2S, Benzene, Water) on Carbon Materials

2021 ◽  
pp. 79-111
Author(s):  
Lumeng Liu ◽  
Shiliang (Johnathan) Tan ◽  
D. D. Do
Keyword(s):  
Computer Simulation ◽  
Carbon Materials ◽  
Experimental Studies

scholarly journals Improvement Dependability of Offshore Horizontal-Axis Wind Turbines by Applying New Mathematical Methods for Calculation the Excess Speed in Case of Wind Gusts

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3085
Author(s):  
Konstantin Osintsev ◽  
Seregei Aliukov ◽  
Alexander Shishkov
Keyword(s):  
Computer Simulation ◽  
Wind Turbines ◽  
Experimental Studies ◽  
Offshore Wind ◽  
Approximation Schemes ◽  
Calculation Error ◽  
Strong Wind ◽  
Mathematical Methods ◽  
Wind Gusts ◽  
Gas Dynamic

The problem of increasing the reliability of wind turbines exists in the development of new offshore oil and natural gas fields. Reducing emergency situations is necessary due to the autonomous operation of drilling rigs and bulk seaports in the subarctic and Arctic climate. The relevance of the topic is linked with the development of a methodology for theoretical and practical studies of gas dynamics when gas flows in a pipe, based on a mathematical model using new mathematical methods for calculation of excess speeds in case of wind gusts. Problems in the operation of offshore wind turbines arise with storm gusts of wind, which is comparable to the wave movement of the gas flow. Thus, the scientific problem of increasing the reliability of wind turbines in conditions of strong wind gusts is solved. The authors indicate a gross error in the calculations when approximating through the use of the Fourier series. The obtained results will allow us to solve one of the essential problems of modeling at this stage of its development, namely: to reduce the calculation time and the adequacy of the model built for similar installations and devices. Experimental studies of gas-dynamic flows are carried out on the example of a physical model of a wind turbine. In addition, a computer simulation of the gas-dynamic flow process was carried out. The use of new approximation schemes in processing the results of experiments and computer simulation can reduce the calculation error by 1.2 percent.

scholarly journals Finite Element Prediction for the Internal Stresses of (Ti,Al)N Coatings

2016 ◽  
Vol 61 (1) ◽  
pp. 149-152 ◽  
Author(s):  
L.W. Żukowska ◽  
A. Śliwa ◽  
J. Mikuła ◽  
M. Bonek ◽  
W. Kwaśny ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Computer Simulation ◽  
Finite Element ◽  
Experimental Studies ◽  
Single Layer ◽  
Internal Stresses ◽  
Pvd Coatings ◽  
Properties Of Coatings ◽  
Gradient Coatings ◽  
Element Method

The general topic of this paper is the computer simulation with use of finite element method (FEM) for determining the internal stresses of selected gradient and single-layer PVD coatings deposited on the sintered tool materials, including cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics by cathodic arc evaporation CAE-PVD method. Developing an appropriate model allows the prediction of properties of PVD coatings, which are also the criterion of their selection for specific items, based on the parameters of technological processes. In addition, developed model can to a large extent eliminate the need for expensive and time-consuming experimental studies for the computer simulation. Developed models of internal stresses were performed with use of finite element method in ANSYS environment. The experimental values of stresses were calculated using the X-ray sin2ψ technique. The computer simulation results were compared with the experimental results. Microhardness and adhesion as well as wear range were measured to investigate the influence of stress distribution on the mechanical and functional properties of coatings. It was stated that occurrence of compressive stresses on the surface of gradient coating has advantageous influence on their mechanical properties, especially on microhardness. Absolute value reduction of internal stresses in the connection zone in case of the gradient coatings takes profitably effects on improvement the adhesion of coatings. It can be one of the most important reasons of increase the wear resistance of gradient coatings in comparison to single-layer coatings.

scholarly journals Weaving the Common Threads of Simulation and Formation studies in Archaeology

2017 ◽  
Author(s):  
Benjamin Davies
Keyword(s):  
Computer Simulation ◽  
Human Activity ◽  
Computational Models ◽  
Experimental Studies ◽  
Surface Erosion ◽  
Archaeological Record ◽  
The Common ◽  
The Relationship ◽  
Material Record

Computer simulation is a tool increasingly used by archaeologists to build theories about past human activity; however, simulation has had a limited role theorising about the relationship between past behaviours and the formation of observed patterning in the material record. This paper visits the argument for using simulation as a means of addressing the gap that exists between archaeological interpretations of past behaviours and their physical residues. It is argued that simulation is used for much the same reason that archaeologists use ethnographic or experimental studies, and that computational models can help to address some of the practical limitations of these approaches to record formation. A case study from arid Australia, examining the effects of episodic surface erosion on the visibility of the record, shows how simple, generative simulations, grounded in formational logic, can be used to compare different explanatory mechanisms and suggest tests of the archaeological record itself.

scholarly journals Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint-formation and computer simulation

2011 ◽  
Vol 9 (69) ◽  
pp. 707-719 ◽  
Author(s):  
Robin H. Crompton ◽  
Todd C. Pataky ◽  
Russell Savage ◽  
Kristiaan D'Août ◽  
Matthew R. Bennett ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Experimental Studies ◽  
Strong Support ◽  
Foot Pressure ◽  
Human Foot ◽  
Simulation Techniques ◽  
Force Transfer ◽  
Functional Features ◽  
Early Human ◽  
Computer Simulation Techniques

It is commonly held that the major functional features of the human foot (e.g. a functional longitudinal medial arch, lateral to medial force transfer and hallucal (big-toe) push-off) appear only in the last 2 Myr, but functional interpretations of footbones and footprints of early human ancestors (hominins) prior to 2 million years ago (Mya) remain contradictory. Pixel-wise topographical statistical analysis of Laetoli footprint morphology, compared with results from experimental studies of footprint formation; foot-pressure measurements in bipedalism of humans and non-human great apes; and computer simulation techniques, indicate that most of these functional features were already present, albeit less strongly expressed than in ourselves, in the maker of the Laetoli G-1 footprint trail, 3.66 Mya. This finding provides strong support to those previous studies which have interpreted the G-1 prints as generally modern in aspect.

Counterflow in isotachophoresis: Computer simulation and experimental studies

1993 ◽  
Vol 14 (1) ◽  
pp. 205-213 ◽  
Author(s):  
Ranjit R. Deshmukh ◽  
Milan Bier
Keyword(s):  
Computer Simulation ◽  
Experimental Studies

scholarly journals Methane Adsorption on Heteroatom-Modified Maquettes of Porous Carbon Surfaces

2021 ◽  
Author(s):  
Rylan Rowsey ◽  
Erin E Taylor ◽  
Stephan Irle ◽  
Nicholas P Stadie ◽  
Robert Szilagyi
Keyword(s):  
Porous Carbon ◽  
Density Functional ◽  
Rational Design ◽  
Carbon Materials ◽  
Computational Cost ◽  
Experimental Studies ◽  
Methane Adsorption ◽  
Basis Set ◽  
Edge Structure ◽  
Carbon Surfaces

<div> <div> <div> <p>Experimental studies and theoretical models presently disagree on methane adsorption energetics on carbon materials that include crystalline graphene-like structures to amorphous materials with or without significant edge structure. However, this information is critical for the rational design and optimization of the structure and composition of adsorbents for natural gas storage. The delicate nature of the interactions inherent to methane physisorption, such as dispersion interactions, polarization of both the adsorbent and the adsorbate, interplay between H- bonding and tetrel bonding, and induced dipole/Coulomb interactions, requires computational treatment at the highest possible level of theory while remaining non-prohibitive in terms of computational cost. In this study, we employ the smallest reasonable computational model, a maquette, of porous carbon surfaces with a central atomic binding site for substitution. The most accurate predictions of the methane adsorption energetics were achieved by electron-correlated molecular orbital theory (CCSD(T)) and hybrid density functional theory (MN15) calculations, both employing a saturated all-electron basis set. The characteristic geometry of methane adsorption on a carbon surface was likened to a “lander” position over the ring centers of the adsorbent. This adsorbate/adsorbent arrangement arises due to bonding interactions of the adsorbent π-system with the proximal H–C bonds of methane, in addition to tetrel bonding between the antibonding orbital of the distal C–H bond and the central atom of the maquette (C, B, or N). The polarization of the electron density as well as structural deformations in both the adsorbate and adsorbent molecules clearly indicate a ~3 kJ mol-1 preference for methane binding on the N-substituted maquette. In this study, the B-substituted maquette showed a comparable or lower binding energy than the unsubstituted, pure C model, depending on the level of theory employed. The calculated thermodynamic results indicate an unambiguous guiding strategy toward incorporating electron- enriched substitutions (e.g., N) in carbon materials as a way to increase methane storage capacity over electron deficient (e.g., B) modifications. The thermochemical calculation methodologies were critically evaluated in order to establish a conceptual agreement between the experimental isosteric heat of adsorption and the binding enthalpies/free energies from statistical thermodynamics principles. </p> </div> </div> </div>

scholarly journals Methane Adsorption on Heteroatom-Modified Maquettes of Porous Carbon Surfaces

2021 ◽  
Author(s):  
Rylan Rowsey ◽  
Erin E Taylor ◽  
Stephan Irle ◽  
Nicholas P Stadie ◽  
Robert Szilagyi
Keyword(s):  
Porous Carbon ◽  
Density Functional ◽  
Rational Design ◽  
Carbon Materials ◽  
Computational Cost ◽  
Experimental Studies ◽  
Methane Adsorption ◽  
Basis Set ◽  
Edge Structure ◽  
Carbon Surfaces

<div> <div> <div> <p>Experimental studies and theoretical models presently disagree on methane adsorption energetics on carbon materials that include crystalline graphene-like structures to amorphous materials with or without significant edge structure. However, this information is critical for the rational design and optimization of the structure and composition of adsorbents for natural gas storage. The delicate nature of the interactions inherent to methane physisorption, such as dispersion interactions, polarization of both the adsorbent and the adsorbate, interplay between H- bonding and tetrel bonding, and induced dipole/Coulomb interactions, requires computational treatment at the highest possible level of theory while remaining non-prohibitive in terms of computational cost. In this study, we employ the smallest reasonable computational model, a maquette, of porous carbon surfaces with a central atomic binding site for substitution. The most accurate predictions of the methane adsorption energetics were achieved by electron-correlated molecular orbital theory (CCSD(T)) and hybrid density functional theory (MN15) calculations, both employing a saturated all-electron basis set. The characteristic geometry of methane adsorption on a carbon surface was likened to a “lander” position over the ring centers of the adsorbent. This adsorbate/adsorbent arrangement arises due to bonding interactions of the adsorbent π-system with the proximal H–C bonds of methane, in addition to tetrel bonding between the antibonding orbital of the distal C–H bond and the central atom of the maquette (C, B, or N). The polarization of the electron density as well as structural deformations in both the adsorbate and adsorbent molecules clearly indicate a ~3 kJ mol-1 preference for methane binding on the N-substituted maquette. In this study, the B-substituted maquette showed a comparable or lower binding energy than the unsubstituted, pure C model, depending on the level of theory employed. The calculated thermodynamic results indicate an unambiguous guiding strategy toward incorporating electron- enriched substitutions (e.g., N) in carbon materials as a way to increase methane storage capacity over electron deficient (e.g., B) modifications. The thermochemical calculation methodologies were critically evaluated in order to establish a conceptual agreement between the experimental isosteric heat of adsorption and the binding enthalpies/free energies from statistical thermodynamics principles. </p> </div> </div> </div>

scholarly journals Mining excavator working equipment load forecasting according to a fuzzy-logistic model

2020 ◽  
Vol 241 ◽  
pp. 29
Author(s):  
V. Velikanov
Keyword(s):  
Computer Simulation ◽  
Fuzzy Logic ◽  
Statistical Analysis ◽  
Logistic Model ◽  
Load Forecasting ◽  
Experimental Studies ◽  
Multiple Stress ◽  
Accurate Forecast ◽  
Analytical Formulas ◽  
Qualitative Nature

Due to the fact that the loads occurring in the working equipment of mining excavators are determined by a large number of random factors that are difficult to represent by analytical formulas, for estimating and predicting loads the models must be introduced using non-standard approaches. In this study, we used the methodology of the theory of fuzzy logic and fuzzy pluralities, which allows to overcome the difficulties associated with the incompleteness and vagueness of the data in assessing and predicting the  forces encountered in the working equipment of mining excavators, as well as with the qualitative nature of these data.As a result of computer simulation in the fuzzyTECH environment, data comparable with experimental studies were obtained to determine the level of loading of the main elements of the working equipment of mining excavators. Based on a representative sample, a statistical analysis of the data was performed, as a result of which the equation of linear multiple stress regression in the handle of mining excavators was obtained, which allows to make an accurate forecast of the loading of the working equipment of the excavator.

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