Mathematic simulation of atomic structure of multicomponent oxide-fluoride melt for continuous casting machines

Determination of relation between oxides melts properties, based on silicates and calcium alum-silicates and magnesium and their chemical composition and structure is an important condition to provide a rational slag mode in a continuous casting machines mold. A mathematical simulation of slag melts and casting powders accomplished. The oxide-fluoride system was chosen for the simulation, for which the structure after solidification was determined by experiment. Results of molecular-dynamic simulation of CaO–SiO2–Al2O3–MgO–Na2O–K2O–CaF2–FeO system, correspondent to industrial casting powders composition, used during steel casting for slag formation in a CCM mold (35.35 % SiO2; 30.79 % CaO; 8.58 % Al2O3; 1.26 % MgO; 13.73 % CaF2; 7.57 % Na2O; 0.88 % K2O; 1.82 % FeO). Taking into account the concentration, a re-calculation was accomplished to mole shares and correspondent number of ions in the model for each component calculated. Simulation of the 8-component oxide-fluoride melt with 2003 ions size in the main cube (a side length of 31.01 Å) was accomplished at the experimentally determined temperature of solidification onset (1257 K) under periodic boundary conditions and fixed volume. The Coulomb interaction was taken into account by the Ewald–Hansen method. The time step was 0.05t0, where t0 = 7,608×10–14 sec is the internal unit of time. The melt density was taken as 3.04 g/cm3 based on the experimental data. The inter-particle interaction potentials were chosen in the Born–Mayer form. According to the simulation results, the structure of sub-crystalline groups of atoms present in the melt at the temperature of the onset of solidification was determined. A discussion of the simulation results and their comparison with the literature data presented.

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MOLECULAR DYNAMIC SIMULATION OF THE MELT OF OXIDE-FLUORIDE INDUSTRIAL SLAG-FORMING MIXTURE

Izvestiya Ferrous Metallurgy ◽

10.17073/0368-0797-2019-9-719-724 ◽

2019 ◽

Vol 62 (9) ◽

pp. 719-724

Author(s):

B. R. Gel’chinskii ◽

E. V. Dyul’dina ◽

L. I. Leont’ev

Keyword(s):

Molecular Dynamic Simulation ◽

Molecular Dynamic ◽

Dynamic Simulation ◽

Continuous Casting Machine ◽

Casting Machine ◽

Time Step ◽

Form Complex ◽

Oxygen Tetrahedron ◽

Simulation Results ◽

Slag Melts

The paper discusses the results of molecular dynamic simulation of a melt of the multicomponent oxide-fluoride system CaO – SiO2 – – Al2O3 – MgO – Na2O – K2O – CaF2 – FeO, corresponding to composition of industrial slag-forming mixture (SFM) used in steel casting for slag targeting in the mold of a continuous casting machine (in wt %: 35.35 % SiO2 , 30.79 % CaO, 8.58 % Al2O3 , 1.26 % MgO, 13.73 % CaF2 , 7.57 % Na2O, 0.88 % K2O, and 1.82 % FeO). These concentrations were converted to mole fractions, and the number of ions was calculated for each of the components in the model. An eightcomponent oxide-fluoride melt containing 2003 ions in the main cube with a side length of 31.01 Å was simulated under periodic boundary conditions at an experimentally determined solidification onset temperature of 1257 K at constant volume. Coulomb interaction was taken into account by the Ewald–Hansen method. The time step was 0.05t0, where t0 = 7,608·10–14 s is the internal unit of time. The melt density was taken to be 3.04 g/cm3 based on our experimental data. The interparticle interaction potentials were chosen in the Born–Mayer form. Based on the simulation results, the structure of subcrystalline groups of atoms present in the melt at the temperature of solidification onset was determined. A discussion of the simulation results and their comparison with the literature data was held. It is shown that the computer model allows one to obtain a fairly realistic picture of atomic structure of the slag melt, indicating that the main structural component of all silicate systems is silicon-oxygen tetrahedron. Tetrahedra in silicates are either in the form of structural units isolated from each other, or, connecting together through peaks, they form complex anions. It is consistent with the theory of slag melts. Molecular-dynamic simulation allows one to obtain adequate information on structure of the melt of a certain chemical composition.

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On the Collision Detection for Ellipsoidal Particles in Turbulence

Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations ◽

10.1115/fedsm2014-21982 ◽

2014 ◽

Cited By ~ 1

Author(s):

Christoph Siewert ◽

Rudie P. J. Kunnen ◽

Matthias Meinke ◽

Wolfgang Schröder

Keyword(s):

Collision Detection ◽

Analytical Formula ◽

Collision Probability ◽

Spherical Particles ◽

Detection Methods ◽

Time Step ◽

Important Condition ◽

Ellipsoidal Particles ◽

Continuous Collision Detection

Collisions of small and heavy non-spherical particles settling in a turbulent environment are very important to various fields of physics and engineering. However, in contrast to spherical particles the collision probabilities are virtually unknown. In this study we focus on a very important condition for the numerical determination of collision probabilities: the collision detection. We discuss the need for efficient strategies to narrow down the number of possible collision pairs and compare three collision detection methods for ellipsoidal particles. We derive an analytical formula for the collision probability in the case of gravitational settling and validate the collision detection methods with this. Finally, we present statistics of the accuracy and efficiency of the methods. For the case of ellipsoidal particles in turbulence we find that the continuous collision detection with neglected rotation within a time step is the optimal trade-off between accuracy and efficiency.

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Is Hydraulics Over-Used or Under-Used in Storm Drainage?

Water Science & Technology ◽

10.2166/wst.1994.0651 ◽

1994 ◽

Vol 29 (1-2) ◽

pp. 53-61

Author(s):

Ben Chie Yen

Keyword(s):

Unsteady Flow ◽

Computational Time ◽

Time Step ◽

Flow Routing ◽

Kinematic Wave Equation ◽

Storm Drainage ◽

Saint Venant Equations ◽

Unsteady Flow Routing ◽

Selection Of

Urban drainage models utilize hydraulics of different levels. Developing or selecting a model appropriate to a particular project is not an easy task. Not knowing the hydraulic principles and numerical techniques used in an existing model, users often misuse and abuse the model. Hydraulically, the use of the Saint-Venant equations is not always necessary. In many cases the kinematic wave equation is inadequate because of the backwater effect, whereas in designing sewers, often Manning's formula is adequate. The flow travel time provides a guide in selecting the computational time step At, which in turn, together with flow unsteadiness, helps in the selection of steady or unsteady flow routing. Often the noninertia model is the appropriate model for unsteady flow routing, whereas delivery curves are very useful for stepwise steady nonuniform flow routing and for determination of channel capacity.

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Theoretical determination of monostatic co- & cross-linearly polarized radar cross section of a missile at each point of missile trajectory - Part II: Simulation results

2008 International Conference on Recent Advances in Microwave Theory and Applications ◽

10.1109/amta.2008.4763234 ◽

2008 ◽

Cited By ~ 1

Author(s):

R. K. Dutta

Keyword(s):

Cross Section ◽

Radar Cross Section ◽

Theoretical Determination ◽

Linearly Polarized ◽

Simulation Results

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A NEW TECHNIQUE ESTIMATING LOCATION OF MEAN JOINT CENTERS OF ROTATION WITH ASSOCIATED DISPERSIONS AND ASSESSING TO FUNCTIONAL COORDINATE SYSTEM OF MOVING LIMB SEGMENTS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519406001996 ◽

2006 ◽

Vol 06 (04) ◽

pp. 373-384

Author(s):

ERIC BERTHONNAUD ◽

JOANNÈS DIMNET

Keyword(s):

Numerical Technique ◽

New Technique ◽

Helical Axis ◽

Joint Movement ◽

Time Step ◽

Data Set ◽

Minimization Procedure ◽

A New Technique ◽

Joint Center

Joint centers are obtained from data treatment of a set of markers placed on the skin of moving limb segments. Finite helical axis (FHA) parameters are calculated between time step increments. Artifacts associated with nonrigid body movements of markers entail ill-determination of FHA parameters. Mean centers of rotation may be calculated over the whole movement, when human articulations are likened to spherical joints. They are obtained using numerical technique, defining point with minimal amplitude, during joint movement. A new technique is presented. Hip, knee, and ankle mean centers of rotation are calculated. Their locations depend on the application of two constraints. The joint center must be located next to the estimated geometric joint center. The geometric joint center may migrate inside a cube of possible location. This cube of error is located with respect to the marker coordinate systems of the two limb segments adjacent to the joint. Its position depends on the joint and the patient height, and is obtained from a stereoradiographic study with specimen. The mean position of joint center and corresponding dispersion are obtained through a minimization procedure. The location of mean joint center is compared with the position of FHA calculated between different sequential steps: time sequential step, and rotation sequential step where a minimal rotation amplitude is imposed between two joint positions. Sticks are drawn connecting adjacent mean centers. The animation of stick diagrams allows clinical users to estimate the displacements of long bones (femur and tibia) from the whole data set.

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Downtime Analysis Techniques for Complex Offshore and Dredging Operations

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 2 ◽

10.1115/omae2004-51113 ◽

2004 ◽

Author(s):

Remmelt J. van der Wal ◽

Gerrit de Boer

Keyword(s):

Wind Waves ◽

Weather Forecast ◽

Offshore Structures ◽

Operational Mode ◽

Offshore Structure ◽

Hydrodynamic Models ◽

Time Step ◽

Made In

Offshore operations in open seas may be seriously affected by the weather. This can lead to a downtime during these operations. The question whether an offshore structure or dredger is able to operate in wind, waves and current is defined as “workability”. In recent decades improvements have been made in the hydrodynamic modelling of offshore structures and dredgers. However, the coupling of these hydrodynamic models with methods to analyse the actual workability for a given offshore operation is less developed. The present paper focuses on techniques to determine the workability (or downtime) in an accurate manner. Two different methods of determining the downtime are described in the paper. The first method is widely used in the industry: prediction of downtime on basis of wave scatter diagrams. The second method is less common but results in a much more reliable downtime estimate: determination of the ‘job duration’ on basis of scenario simulations. The analysis using wave scatter diagrams is simple: the downtime is expressed as a percentage of the time (occurrences) that a certain operation can not be carried out. This method can also be used for a combination of operations however using this approach does not take into account critical events. This can lead to a significant underprediction of the downtime. For the determination of the downtime on basis of scenario simulations long term seastate time records are used. By checking for each subsequent time step which operational mode is applicable and if this mode can be carried out the workability is determined. Past events and weather forecast are taken into account. The two different methods are compared and discussed for a simplified offloading operation from a Catenary Anchor Leg Mooring (CALM) buoy. The differences between the methods will be presented and recommendations for further applications are given.

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Determination of the Minimum Distance Between Moving Objects Including Velocity Information

19th Design Automation Conference: Volume 1 — Mechanical System Dynamics; Concurrent and Robust Design; Design for Assembly and Manufacture; Genetic Algorithms in Design and Structural Optimization ◽

10.1115/detc1993-0361 ◽

1993 ◽

Author(s):

Meyer Nahon

Keyword(s):

Minimum Distance ◽

Moving Objects ◽

Rapid Determination ◽

Computation Time ◽

Optimization Techniques ◽

Real Time Control ◽

Time Step ◽

Time Control ◽

Velocity Information

Abstract The rapid determination of the minimum distance between objects is of importance in collision avoidance for a robot maneuvering among obstacles. Currently, the fastest algorithms for the solution of this problem are based on the use of optimization techniques to minimize a distance function. Furthermore, to date this problem has been approached purely through the position kinematics of the two objects. However, although the minimum distance between two objects can be found quickly on state-of-the-art hardware, the modelling of realistic scenes entails the determination of the minimum distances between large numbers of pairs of objects, and the computation time to calculate the overall minimum distance between any two objects is significant, and introduces a delay which has serious repercussions on the real-time control of the robot. This paper presents a technique to modify the original optimization problem in order to include velocity information. In effect, the minimum distance calculation is performed at a future time step by projecting the effect of present velocity. This method has proven to give good results on a 6-dof robot maneuvering among obstacles, and has allowed a complete compensation of the lags incurred due to computational delays.

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Path Following System for Cooperative Mobile Robots

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.166-167.161 ◽

2010 ◽

Vol 166-167 ◽

pp. 161-166

Author(s):

Ionut Dinulescu ◽

Dorin Popescu ◽

Mircea Nitulescu ◽

Alice Predescu

Keyword(s):

Artificial Intelligence ◽

Mobile Robots ◽

Path Following ◽

Path Generation ◽

Cooperative Robots ◽

Generation System ◽

Robot Systems ◽

Simulation Results ◽

Trajectory Generator

Recent advances in the domains of social and life artificial intelligence have constituted the basis for a new discipline that studies cooperation in multi-robot systems and its utility in applications where some tasks cannot be carried out by a single robot. This paper introduces a trajectory generator which is used for determination of the most appropriate trajectory which a robot needs to track in order to perform different tasks specific to cooperative robots, such as moving in a given formation or pushing an object to a given destination. Different algorithms are described in this paper, starting from simple polyline and circular paths to complex Bezier trajectories. Simulation results of the proposed path generation system are also provided, along with the description of its implementation on real mobile robots. An implementation of real robots is also presented in this paper.

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Structure investigations of layered soil – varved clay

Annals of Warsaw University of Life Sciences – SGGW Land Reclamation ◽

10.1515/sggw-2016-0028 ◽

2016 ◽

Vol 48 (4) ◽

pp. 365-375 ◽

Cited By ~ 1

Author(s):

Matylda Tankiewicz

Keyword(s):

Mechanical Behavior ◽

Internal Structure ◽

Strength Properties ◽

Layered Soil ◽

Radiographic Images ◽

Composition And Structure ◽

Computed Microtomography ◽

Structure Investigations ◽

Varved Clay

Abstract In the paper the results of laboratory investigations of structure of layered soil are presented. They focus on varved clay that is a soil composed of two alternately arranged varves with different texture and mechanical properties. An effect of such structure is an anisotropy of the material. Due to varying conditions during its formation process the soil exhibits some irregularities in composition and structure. Due to that modelling of mechanical behavior, like strength, may not provide satisfactory results. Main purpose of the examinations is an investigation of internal structure of layered soil – varved clay – in relation to its strength anisotropy and evaluation of the suitability of the use of two different techniques to assess the soil structure. Investigated material have been taken from area near city of Bełchatów in central Poland. The examinations included investigation of particle size distribution of soil and its components, identification of lamination with use of scanning electron microscope (SEM) and computed microtomography technique (μCT). First, the texture of each varve and varved clay as a composite have been estimated. Next, the investigation of surface perpendicular to the lamination have been carried out with SEM. Pictures of varves with different magnifications are presented. Also the varves arrangement and details of layers contact area are shown. Finally, investigation of internal structure of the soil have been performed by using microtomograph. The outcome is a series of radiographic images and reconstructed 3D model of tested soil. Presented results show complexity of the structure of varved clay that affect the mechanical behavior. Determination of the structure with use of presented techniques may be helpful in examination of strength properties and proper modeling of such soil.

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