scholarly journals Follow-the-Leader Approximations of Macroscopic Models for Vehicular and Pedestrian Flows

2017 ◽  
pp. 333-378 ◽  
Author(s):  
M. Di Francesco ◽  
S. Fagioli ◽  
M. D. Rosini ◽  
G. Russo
Keyword(s):  
Macroscopic Models

Stochastic homogenization and macroscopic modelling of composites and flow through porous media

2002 ◽  
pp. 337-378 ◽  
Author(s):  
Jozef Telega ◽  
Wlodzimierz Bielski
Keyword(s):  
Porous Medium ◽  
Random Distribution ◽  
Flow Through Porous Media ◽  
Macroscopic Models ◽  
Linear Elastic ◽  
Multi Scale ◽  
Convergence Method ◽  
Flow Through ◽  
The Mean ◽  
Random Porous Medium

The aim of this contribution is mainly twofold. First, the stochastic two-scale convergence in the mean developed by Bourgeat et al. [13] is used to derive the macroscopic models of: (i) diffusion in random porous medium, (ii) nonstationary flow of Stokesian fluid through random linear elastic porous medium. Second, the multi-scale convergence method developed by Allaire and Briane [7] for the case of several microperiodic scales is extended to random distribution of heterogeneities characterized by separated scales (stochastic reiterated homogenization). .

scholarly journals Ranking the critical sections of railway networks

2020 ◽  
pp. 095440972092568
Author(s):  
Ratthaphong Meesit ◽  
John Andrews
Keyword(s):  
Network Flow ◽  
Topological Analysis ◽  
Preventive Strategy ◽  
Railway Network ◽  
Macroscopic Models ◽  
Railway Systems ◽  
Railway Networks ◽  
Network Simulation Model ◽  
The Impact ◽  
Critical Sections

Railway systems are now facing an increasing number of threats such as aging infrastructures and climate changes. The identification of critical network sections provides infrastructure managers with the ability to understand the impact of a disruption and creates a suitable preventive strategy to counter such threats. To this end, various vulnerability analysis methods have been proposed for railway networks. Two main types of methods, network topological analysis and network flow-based analysis, have been developed. Both approaches are constructed based on macroscopic models, which take only some railway properties such as network structure, train and passenger flow into account. Thus, the results obtained are high level approximations. This study proposes a new analysis method, which is developed based on the stochastic-microscopic railway network simulation model. The method can be applied to identify the critical sections of a railway network. The effect of impact levels and occurrence times of a disruption on the network section criticality is presented. An application of the proposed model is demonstrated using the Liverpool railway network in the UK.

scholarly journals Investigation of representing hysteresis in macroscopic models of two-phase flow in porous media using intermediate scale experimental data

2017 ◽  
Vol 53 (1) ◽  
pp. 199-221 ◽  
Author(s):  
Abdullah Cihan ◽  
Jens Birkholzer ◽  
Luca Trevisan ◽  
Ana Gonzalez-Nicolas ◽  
Tissa Illangasekare
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Two Phase Flow ◽  
Flow In Porous Media ◽  
Phase Flow ◽  
Two Phase ◽  
Intermediate Scale ◽  
Macroscopic Models

Atomistic Aspects of Fracture Modelling in the Framework of Continuum Mechanics

1998 ◽  
Vol 538 ◽  
Author(s):  
F. Cleri
Keyword(s):  
Continuum Mechanics ◽  
Constitutive Relations ◽  
Point Of View ◽  
Atomic Scale ◽  
Continuum Models ◽  
Cohesive Law ◽  
Macroscopic Models ◽  
Scale Models ◽  
Level Information ◽  
Set Up

AbstractThe validity and predictive capability of continuum models of fracture rests on basic informations whose origin lies at the atomic scale. Examples of such crucial informations are, e.g., the explicit form of the cohesive law in the Barenblatt model and the shear-displacement relation in the Rice-Peierls-Nabarro model. Modem approaches to incorporate atomic-level information into fracture modelling require to increase the size of atomic-scale models up to millions of atoms and more; or to connect directly atomistic and macroscopic, e.g. finite-elements, models; or to pass information from atomistic to continuum models in the form of constitutive relations. A main drawback of the atomistic methods is the complexity of the simulation results, which can be rather difficult to rationalize in the framework of classical, continuum fracture mechanics. We critically discuss the main issues in the atomistic simulation of fracture problems (and dislocations, to some extent); our objective is to indicate how to set up atomistic simulations which represent well-posed problems also from the point of view of continuum mechanics, so as to ease the connection between atomistic information and macroscopic models of fracture.

scholarly journals Microscopic and macroscopic models for the onset and progression of Alzheimer's disease

2017 ◽  
Vol 50 (41) ◽  
pp. 414003 ◽  
Author(s):  
Michiel Bertsch ◽  
Bruno Franchi ◽  
Maria Carla Tesi ◽  
Andrea Tosin
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Macroscopic Models

Disordering of MgAl2O4 spinel from first principles

2000 ◽  
Vol 64 (2) ◽  
pp. 311-317 ◽  
Author(s):  
M. C. Warren ◽  
M. T. Dove ◽  
S. A. T. Redfern
Keyword(s):  
Free Energy ◽  
Electronic Structure ◽  
First Principles ◽  
Large Scale ◽  
Experimental Measurements ◽  
Zero Temperature ◽  
Macroscopic Models ◽  
Tetrahedral Sites ◽  
Degree Of Order ◽  
Good Agreement

AbstractAt high temperature, MgAl2O4 spinel is stabilized by disorder of Mg and Al between octahedral and tetrahedral sites. This behaviour has been measured up to 1700 K in recent neutron experiments, but the extrapolation of subsequently fitted thermodynamic models is not reliable. First principles simulation of the electronic structure of such minerals can in principle accurately predict disorder, but would require unfeasibly large computing resources. We have instead parameterized on-site and short-ranged cluster potentials using a small number of electronic structure simulations at zero temperature. These potentials were then used in large-scale statistical simulations at finite temperatures to predict disordering thermodynamics beyond the range of experimental measurements. Within the temperature range of the experiment, good agreement is obtained for the degree of order. The entropy and free energy are calculated and compared to those from macroscopic models.

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.

Macroscopic models for sound propagation in normal liquid3He

1985 ◽  
Vol 6 (5) ◽  
pp. 445-467 ◽  
Author(s):  
F. Dalfovo ◽  
S. Stringari
Keyword(s):  
Sound Propagation ◽  
Macroscopic Models
Sign in / Sign up

Export Citation Format

Share Document