Effect of the initial domain on the dispersion dynamics of a diffusing substance

2018 ◽  
Author(s):  
A. N. Bestuzheva ◽  
A. L. Smirnov
Keyword(s):  
Initial Domain

scholarly journals Linearization of multi-output logic functions by ordering of the autocorrelation values

2007 ◽  
Vol 20 (3) ◽  
pp. 479-498 ◽  
Author(s):  
Osnat Keren ◽  
Ilya Levin
Keyword(s):  
Computational Complexity ◽  
Boolean Function ◽  
Autocorrelation Function ◽  
Execution Time ◽  
Boolean Functions ◽  
Analytic Method ◽  
Implementation Cost ◽  
Initial Domain ◽  
Greedy Methods ◽  
Logic Functions

The paper deals with the problem of linear decomposition of a system of Boolean functions. A novel analytic method for linearization, by reordering the values of the autocorrelation function, is presented. The computational complexity of the linearization procedure is reduced by performing calculations directly on a subset of autocorrelation values rather than by manipulating the Boolean function in its initial domain. It is proved that unlike other greedy methods, the new technique does not increase the implementation cost. That is, it provides linearized functions with a complexity that is not greater than the complexity of the initial Boolean functions. Experimental results over standard benchmarks and random Boolean functions demonstrate the efficiency of the proposed procedure in terms of the complexity measure and the execution time.

Investigations on Multi-axial Domain Switching Criteria for Piezoceramics

2005 ◽  
Vol 881 ◽  
Author(s):  
Bernd Laskewitz ◽  
Dayu Zhou ◽  
Marc Kamlah
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Domain Switching ◽  
Axial Stress ◽  
Initial Domain ◽  
Hollow Cylinders ◽  
Thin Walled ◽  
Electromechanical Loading ◽  
Stress States ◽  
Strain Responses

AbstractInitially unpoled soft PZT was subjected to a proportional, coaxial electromechanical loading. The ratio of compressive stress to electric field was changed between the experiments. From this series of nonlinear polarization and strain responses were obtained. Based on an offset method, initial domain switching states in the two-dimensional stress-electric field space were determined. In continuum mechanics, thin walled tubes are used to investigate multi-axial stress states. In this context, thin walled means a ratio of wall thickness to radius of 1:10 or thinner. However, simple linear dielectric analysis indicates an inhomogeneous electric field distribution in such geometries.Therefore, the suitability of hollow cylinders (in the range from thick to thin walled tubes) for multi-axial electromechanical experiments has to be investigated. Simulations with a finite element tool based on a phenomenological constitutive model for ferroelectric and ferroelastic hysteresis behavior were performed. The results confirm inhomogeneous distributions of electric fields and stresses after poling. A geometry variation is discussed to minimize these effects.

scholarly journals Hyperbolic normal forms and invariant manifolds: Astronomical applications

2012 ◽  
pp. 1-12 ◽  
Author(s):  
C. Efthymiopoulos
Keyword(s):  
Normal Form ◽  
Invariant Manifolds ◽  
Continuation Method ◽  
Space Mission ◽  
Mission Design ◽  
Unstable Periodic Orbits ◽  
Space Mission Design ◽  
Dynamical Astronomy ◽  
Initial Domain ◽  
Asymptotic Orbits

In recent years, the study of the dynamics induced by the invariant manifolds of unstable periodic orbits in nonlinear Hamiltonian dynamical systems has led to a number of applications in celestial mechanics and dynamical astronomy. Two applications of main current interest are i) space manifold dynamics, i.e. the use of the manifolds in space mission design, and, in a quite different context, ii) the study of spiral structure in galaxies. At present, most approaches to the computation of orbits associated with manifold dynamics (i.e. periodic or asymptotic orbits) rely either on the use of the so-called Poincar? - Lindstedt method, or on purely numerical methods. In the present article we briefly review an analytic method of computation of invariant manifolds, first introduced by Moser (1958), and developed in the canonical framework by Giorgilli (2001). We use a simple example to demonstrate how hyperbolic normal form computations can be performed, and we refer to the analytic continuation method of Ozorio de Almeida and co-workers, by which we can considerably extend the initial domain of convergence of Moser?s normal form.

A Method of Domain Compound Concept Extraction Based on Multilevel Filter

2014 ◽  
Vol 989-994 ◽  
pp. 2292-2296
Author(s):  
Bin Wu ◽  
Liu Bo Ouyang
Keyword(s):  
Information Processing ◽  
Template Matching ◽  
Combination Rule ◽  
Concept Extraction ◽  
Initial Domain ◽  
Text Information ◽  
Extraction Model ◽  
F Measure

Identification and extraction in domain compound concept is the basis of the domain text information processing. This paper builds a multilevel filter extraction model by fusing the thought of statistics and language rule. Firstly, the extraction model screening out domain atomic concept set by using method of improved TF-IDF. We secondly build a space combination rule, screening out initial domain compound concept set. Ultimately we screening out finally domain compound concept set by using POS rules template matching via POS analysis. Experiments show that this method can effectively identify and extract domain compound concept and F-measure has reached 83.9%.

Initial domain structure of hydride vapor phase epitaxy GaAs/Si(001) by using x‐ray standing waves

1996 ◽  
Vol 68 (14) ◽  
pp. 1969-1971 ◽  
Author(s):  
Tomoaki Kawamura ◽  
Hisataka Takenaka ◽  
Takayoshi Hayashi ◽  
Masami Tachikawa ◽  
Hidefumi Mori
Keyword(s):  
Domain Structure ◽  
Vapor Phase ◽  
Standing Waves ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
X Ray ◽  
Initial Domain

scholarly journals A new approach to modelling the two way coupling for momentum transfer in a hollow-cone spray

2017 ◽  
Author(s):  
Andreas Papoutsakis ◽  
Sergei Sazhin ◽  
Steven Begg ◽  
Ionut Danaila ◽  
Francky Luddens
Keyword(s):  
Carrier Phase ◽  
Adaptive Mesh Refinement ◽  
Energy Transport ◽  
Adaptive Mesh ◽  
Lagrangian Approach ◽  
New Approach ◽  
Computational Mesh ◽  
Initial Domain ◽  
Tree Data ◽  
Tree Data Structure

A new approach to modelling the interaction between droplets and the carrier phase is suggested. The new model isapplied to the analysis of a spray injected into a chamber of quiescent air, using an Eulerian-Lagrangian approach. The conservative formulation of the equations for mass, momentum and energy transport is used for the analysis of the carrier phase. The dispersed phase is modelled using the Lagrangian approach with droplets represented by individual parcels.The implementation of the Discontinuous Galerkin method (ForestDG), based on a topological representation of the computational mesh by a hierarchical structure consisting of oct- quad- and binary trees, is used in our analysis. Adaptive mesh refinement (h-refinement) enables us to increase the spatial resolution for the computational mesh in the vicinity of the points of interest such as interfaces, geometrical features, or flow discontinuities. The local increase in the expansion order (p-refinement) at areas of high strain rates or vorticity magnitude results in an increase of the order of the accuracy of discretisation of shear layers and vortices.The initial domain consists of a graph of unitarian-trees representing hexahedral, prismatic and tetrahedral elements. The ancestral elements of the mesh can be split into self-similar elements allowing each tree to grow branches to an arbitrary level of refinement. The connectivity of the elements, their genealogy and their partitioning are described by linked lists of pointers. These are attached to the tree data structure which facilitates the on-the-fly splitting, merging and repartitioning of the computational mesh by rearranging the links of each node of the tree. This enables us to refine the computational mesh in the vicinity of the droplet parcels aiming to accurately resolve the coupling betweenthe two phases.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4671

scholarly journals An accelerated and robust algorithm for ant colony optimization in continuous functions

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Jairo G. de Freitas ◽  
Keiji Yamanaka
Keyword(s):  
Ant Colony Optimization ◽  
Real World ◽  
Optimization Problems ◽  
Search Algorithm ◽  
Optimal Solution ◽  
Great Majority ◽  
Continuous Functions ◽  
Ant Colony ◽  
Range Search ◽  
Initial Domain

AbstractThere is a wide variety of computational methods used for solving optimization problems. Among these, there are various strategies that are derived from the concept of ant colony optimization (ACO). However, the great majority of these methods are limited-range-search algorithms, that is, they find the optimal solution, as long as the domain provided contains this solution. This becomes a limitation, due to the fact that it does not allow these algorithms to be applied successfully to real-world problems, as in the real world, it is not always possible to determine with certainty the correct domain. The article proposes the use of a broad-range search algorithm, that is, that seeks the optimal solution, with success most of the time, even if the initial domain provided does not contain this solution, as the initial domain provided will be adjusted until it finds a domain that contains the solution. This algorithm called ARACO, derived from RACO, makes for the obtaining of better results possible, through strategies that accelerate the parameters responsible for adjusting the supplied domain at opportune moments and, in case there is a stagnation of the algorithm, expansion of the domain around the best solution found to prevent the algorithm becoming trapped in a local minimum. Through these strategies, ARACO obtains better results than its predecessors, in relation to the number of function evaluations necessary to find the optimal solution, in addition to its 100% success rate in practically all the tested functions, thus demonstrating itself as being a high performance and reliable algorithm. The algorithm has been tested on some classic benchmark functions and also on the benchmark functions of the IEEE Congress of Evolutionary Computation Benchmark Test Functions (CEC 2019 100-Digit Challenge).

Estimation of the regions of attraction for autonomous nonlinear systems

2018 ◽  
Vol 41 (1) ◽  
pp. 97-106
Author(s):  
Guoqiang Yuan ◽  
Yinghui Li
Keyword(s):  
Nonlinear Systems ◽  
Iterative Methods ◽  
Jacobi Equation ◽  
Time Dependent ◽  
Implicit Function ◽  
Region Of Attraction ◽  
Sublevel Set ◽  
Initial Domain ◽  
Regions Of Attraction ◽  
Hamilton Jacobi Equation

A methodology for estimating the region of attraction for autonomous nonlinear systems is developed. The methodology is based on a proof that the region of attraction can be estimated accurately by the zero sublevel set of an implicit function which is the viscosity solution of a time-dependent Hamilton–Jacobi equation. The methodology starts with a given initial domain and yields a sequence of region of attraction estimates by tracking the evolution of the implicit function. The resulting sequence is contained in and converges to the exact region of attraction. While alternative iterative methods for estimating the region of attraction have been proposed, the methodology proposed in this paper can compute the region of attraction to achieve any desired accuracy in a dimensionally independent and efficient way. An implementation of the proposed methodology has been developed in the Matlab environment. The correctness and efficiency of the methodology are verified through a few examples.

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