scholarly journals MODELING OF SEMISOLID STRUCTURE FORMATION IN CONTROLLED NUCLEATION METHOD

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4123-4128 ◽  
Author(s):  
X. YAO ◽  
H. WANG
Keyword(s):  
Structure Formation ◽  
Macroscopic Models ◽  
Microscopic Models ◽  
Final Microstructure ◽  
Semisolid Alloys ◽  
Microstructure Morphology ◽  
Controlled Nucleation ◽  
Semi Solid ◽  
Heat Transfer Calculation ◽  
Insight Into

Modeling the semisolid structure formation is of significance in both understanding the mechanisms of the formation of such structure and optimization of the solidification conditions for the required structure. A modified cellular automaton (mCA) model has been developed, which is coupled with macroscopic models for heat transfer calculation and microscopic models for nucleation and grain growth. The mCA model is applied to Al - Si alloys, one of the most widely used semisolid alloys. It predicts microstructure morphology and grain size during semi-solid solidification, and determines the effects of poring temperature and mould temperature on the final microstructure. The simulated results are compared with those obtained experimentally. The resulting simulations give some insight into the mechanisms about the semisolid structure formation in Controlled Nucleation process.

Semisolid Structure Simulation in Controlled Nucleation Process

2006 ◽  
Vol 116-117 ◽  
pp. 614-617 ◽  
Author(s):  
H. Wang ◽  
X.D. Yao
Keyword(s):  
Structure Formation ◽  
Nucleation Process ◽  
Macroscopic Models ◽  
Microscopic Models ◽  
Semisolid Alloys ◽  
Microstructure Morphology ◽  
Controlled Nucleation ◽  
Semi Solid ◽  
Heat Transfer Calculation ◽  
Insight Into

Computer simulation of semisolid structure formation is of significance in both understanding the mechanisms of the formation of such structure and optimization the solidification conditions for the required structure. A modified cellular automaton (mCA) model has been developed, which is coupled with macroscopic models for heat transfer calculation and microscopic models for nucleation and grain growth. The mCA model is applied to Al-Si alloys, one of the most widely used semisolid alloys. It predicts microstructure morphology and grain size during semi-solid solidification, and determines the effects of poring temperature and mould temperature on the final microstructure. The simulated results are compared with those obtained experimentally. The resulting simulations give some insight into the mechanisms about the semisolid structure formation in Controlled Nucleation process.

scholarly journals Influence of Thermal Aging Parameters on the Characteristics of Aluminum Semi-Solid Alloys

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 746 ◽  
Author(s):  
Khaled Ragab ◽  
Mohamed Bouazara ◽  
Xiao Chen
Keyword(s):  
Electron Microscopy ◽  
Aluminum Alloys ◽  
Thermal Aging ◽  
Aging Treatment ◽  
Load Variations ◽  
Transmission Electron ◽  
Semisolid Alloys ◽  
Automotive Parts ◽  
Semi Solid ◽  
Solid Alloys

The current study aimed at analyzing the response of semisolid A357 aluminum alloys to unconventional thermal treatment cycles of T4/T6/T7 conditions. The mechanical, electrical, and microstructural characterizations of such semisolid alloys were investigated. The microstructure evolutions of Fe-intermetallic phases and strengthening precipitates were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The mechanical failure of such semi solid A357 aluminum alloys, used for suspension automotive parts, is mostly related to cracking issues which start from the surface due to hardness problems and propagate due to severe load variations. For these reasons, the multiple thermal aging cycles, in this study, are applied to enhance the mechanical properties and to have compromised values compared to those obtained by standard thermal treatments. The results obtained in this work indicate that the heat treatment of this alloy can be optimized. The results showed that the optimum characteristics of A357 semisolid alloys were obtained by applying thermal under-aging cycle, interrupted thermal aging cycles and a T7/T6 two steps aging treatment condition. The electrical conductivity and electron microscopy were applied in this study to analyze the characteristics of hardening phases formed due to different aging cycles applied to the alloys investigated.

scholarly journals Dynamics of The Tranquil Cosmic Web

2014 ◽  
Vol 11 (S308) ◽  
pp. 77-86
Author(s):  
Adi Nusser
Keyword(s):  
Phase Space ◽  
Structure Formation ◽  
Observational Data ◽  
Space Distribution ◽  
Phase Space Distribution ◽  
Redshift Surveys ◽  
Data Analyses ◽  
Galaxy Redshift ◽  
Insight Into

AbstractThe phase space distribution of matter out to ∼ 100 \rm Mpc is probed by two types of observational data: galaxy redshift surveys and peculiar motions of galaxies. Important information on the process of structure formation and deviations from standard gravity have been extracted from the accumulating data. The remarkably simple Zel'dovich approximation is the basis for much of our insight into the dynamics of structure formation and the development of data analyses methods. Progress in the methodology and some recent results is reviewed.

scholarly journals The influences of the microstructure morphology of A356 alloy on its rheological behavior in the semi-solid state

2001 ◽  
Vol 2 (1) ◽  
pp. 219-223 ◽  
Author(s):  
Yuefeng Zhu ◽  
Jinglin Tang ◽  
Yizhi Xiong ◽  
Zhenning Wu ◽  
Chen Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Rheological Behavior ◽  
A356 Alloy ◽  
Microstructure Morphology ◽  
Semi Solid

PROPERTIES OF SUPERHEAVY NUCLEI IN VARIOUS MACROSCOPIC-MICROSCOPIC MODELS

2005 ◽  
Vol 14 (03) ◽  
pp. 365-372 ◽  
Author(s):  
A. BARAN ◽  
M. KOWAL ◽  
Z. ŁOJEWSKI ◽  
K. SIEJA
Keyword(s):  
Spontaneous Fission ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Electric Quadrupole ◽  
Superheavy Nuclei ◽  
Quadrupole Moments ◽  
Α Decay ◽  
Macroscopic Models ◽  
Microscopic Models ◽  
Three Dimensional Space

In the framework of various macroscopic-microscopic models we examine the ground state properties: separation energies, mean square charge radii, electric quadrupole moments as well as fission barriers, mass parameters, spontaneous fission and α decay half-lives of superheavy nuclei. Four macroscopic models and two models of pairing interactions are applied and studied. The approach is based on the deformed Woods-Saxon potential. Spontaneous fission half-lives are calculated within a multi-dimensional dynamical-programming method where the action integral is minimized within the three dimensional space of the nuclear deformation parameters {β2, β4, β6}.

Comprehensive Kinetic of Defects in a-SI:H

1991 ◽  
Vol 219 ◽  
Author(s):  
David Redfield ◽  
Richard H. Bube
Keyword(s):  
Solar Cells ◽  
Steady State ◽  
Light Intensity ◽  
Rate Equation ◽  
Defect Density ◽  
Microscopic Models ◽  
Dx Center ◽  
Stretched Exponentials ◽  
Kinetics Of ◽  
Insight Into

ABSTRACTLThe introduction of several new principles into the analysis of transition kinetics of metastable defects in a-Si:H has produced substantially improved rate equation for the density of defects as functions of time, light intensity, and temperature. The solution of this equation is stretched exponential (SE) having properties that explain in unifying way many observations of defect properties, including generation and anneal of the defect density in homogeneous films and degradation and anneal of solar cells. Major consequences are found for both the steady-state and transient properties of the defect density and for interpretations of microscopic models of the defects. These properties are also shown to be analogous to those of metastable centers in other materials, particularly the metastable DX center in AlGaAs which offers rare insight into the microscopic origins of stretched exponentials that can be applied to a-Si:H in ways that provide new perspectives on effects of alloying and hydrogen on stability.

MODELS OF TRAFFIC FLOW DYNAMICS ON HIGHWAYS

2021 ◽  
Vol 116 (1) ◽  
pp. 236-241
Author(s):  
Diana Assankhankyzy Otegen
Keyword(s):  
Transport Infrastructure ◽  
Macroscopic Model ◽  
Flow Density ◽  
Traffic Flows ◽  
Macroscopic Models ◽  
The Road ◽  
Advantages And Disadvantages ◽  
Space And Time ◽  
Microscopic Models ◽  
On The Road

The paper is an analytical review of the currently existing methods of traffic flows modeling. The movement of vehicles on the road can be modeled in different ways. Mathematical models as tools that allow us to study complex processes in the real world, including transport infrastructure, without capital expenditures, are a popular tool for solving many problems in various spheres of the national economy. There are several approaches to mathematical modeling of traffic flows. In microscopic models, the law of motion of each car is set, depending on its current position, speed, characteristics of the movement of neighboring cars, and other factors. Microscopic models, in turn, can be divided into models that are continuous in space and time, and into models that are discrete in space and time, the so-called cellular automata. In macroscopic models, the transport flow is considered as a fluid flow with special properties. The equations of the macroscopic model establish the relationship between the flow, density, speed of movement, possibly acceleration, and so on. Macroscopic models can also be continuous or discrete. In continuous models, the change in the state of a road section without branches and intersections is usually described by partial differential equations. Modeling traffic flows is necessary because active experiments in the existing transport network are fraught with unpredictable consequences, and in many cases are not feasible at all. The work presents a description and analysis of the models, and of their advantages and disadvantages.

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