This document describes an iterative domain decomposition method for analyzing large-scale stationary incompressible viscous flow problems using finite element analysis. The method decomposes the domain into subdomains and solves the inner degrees of freedom using a skyline solver. Interface degrees of freedom are solved using preconditioned BiCGSTAB or GPBiCG iterative solvers. Numerical examples are provided to demonstrate the method on problems with over 1 million degrees of freedom and compare results to a monolithic finite element method solver.
Positive and negative solutions of a boundary value problem for a fractional ...journal ijrtem
: In this work, we study a boundary value problem for a fractional
q, -difference equation. By
using the monotone iterative technique and lower-upper solution method, we get the existence of positive or
negative solutions under the nonlinear term is local continuity and local monotonicity. The results show that we
can construct two iterative sequences for approximating the solutions
On prognozisys of manufacturing double basemsejjournal
In this paper we introduce a modification of recently introduced analytical approach to model mass- and
heat transport. The approach gives us possibility to model the transport in multilayer structures with account
nonlinearity of the process and time-varing coefficients and without matching the solutions at the
interfaces of the multilayer structures. As an example of using of the approach we consider technological
process to manufacture more compact double base heterobipolar transistor. The technological approach
based on manufacturing a heterostructure with required configuration, doping of required areas of this heterostructure
by diffusion or ion implantation and optimal annealing of dopant and/or radiation defects. The
approach gives us possibility to manufacture p-n- junctions with higher sharpness framework the transistor.
In this situation we have a possibility to obtain smaller switching time of p-n- junctions and higher compactness
of the considered bipolar transistor.
Existence of positive solutions for fractional q-difference equations involvi...IJRTEMJOURNAL
The existence of positive solutions is considered for a fractional q-difference equation with pLaplacian operator in this article. By employing the Avery-Henderson fixed point theorem, a new result is obtained
for the boundary value problems.
The document discusses techniques for uncertainty propagation and constructing surrogate models. It describes Monte Carlo sampling, analytic techniques, and perturbation techniques for propagating uncertainties in nonlinear models. It also discusses constructing surrogate models such as polynomial, Kriging, and Gaussian process models to approximate computationally expensive discretized partial differential equation models for applications such as Bayesian calibration and design. The document provides an example of constructing a quadratic surrogate model to approximate the response of a heat equation model.
This document discusses uncertainty propagation techniques for determining statistics of model outputs given uncertain model inputs. It covers analytic approaches for linear models, perturbation methods for nonlinear models, and direct sampling methods. It also discusses computing moments using stochastic spectral methods like stochastic Galerkin with polynomial chaos. The document provides an example of applying perturbation and sampling methods to a nonlinear oscillator model with uncertain parameters. It compares the results from both approaches to the true natural frequency. Finally, it discusses uncertainty quantification for a HIV model and the use of prediction intervals in nuclear power plant design.
Lyapunov-type inequalities for a fractional q, -difference equation involvin...IJMREMJournal
The document summarizes a research paper that presents new Lyapunov-type inequalities for a fractional boundary value problem involving a fractional difference equation with a p-Laplacian operator. The paper obtains necessary conditions for the existence of nontrivial solutions to the equation. It also presents some applications to eigenvalue problems. Key concepts from fractional calculus such as fractional derivatives and integrals are reviewed. Lemmas establishing uniqueness of solutions to related problems are also presented.
The document discusses error analysis for quasi-Monte Carlo methods used for numerical integration. It introduces the concepts of reproducing kernel Hilbert spaces and mean square discrepancy to analyze integration error. Specifically, it shows that the mean square discrepancy of randomized low-discrepancy point sets can be computed in O(n) operations, whereas the standard discrepancy requires O(n^2) operations, making randomized quasi-Monte Carlo methods more efficient for high-dimensional integration problems.
IRJET- On Certain Subclasses of Univalent Functions: An ApplicationIRJET Journal
This document presents research on certain subclasses of univalent functions. Specifically, it studies the class WR(λ,β,α,μ,θ) which consists of analytic and univalent functions with negative coefficients in the open disk, defined by the Hadamard product with the Rafid operator. The paper obtains coefficient bounds and extreme points for this class. It also examines the weighted mean, arithmetic mean, and derives some additional results for the class.
Positive and negative solutions of a boundary value problem for a fractional ...journal ijrtem
: In this work, we study a boundary value problem for a fractional
q, -difference equation. By
using the monotone iterative technique and lower-upper solution method, we get the existence of positive or
negative solutions under the nonlinear term is local continuity and local monotonicity. The results show that we
can construct two iterative sequences for approximating the solutions
On prognozisys of manufacturing double basemsejjournal
In this paper we introduce a modification of recently introduced analytical approach to model mass- and
heat transport. The approach gives us possibility to model the transport in multilayer structures with account
nonlinearity of the process and time-varing coefficients and without matching the solutions at the
interfaces of the multilayer structures. As an example of using of the approach we consider technological
process to manufacture more compact double base heterobipolar transistor. The technological approach
based on manufacturing a heterostructure with required configuration, doping of required areas of this heterostructure
by diffusion or ion implantation and optimal annealing of dopant and/or radiation defects. The
approach gives us possibility to manufacture p-n- junctions with higher sharpness framework the transistor.
In this situation we have a possibility to obtain smaller switching time of p-n- junctions and higher compactness
of the considered bipolar transistor.
Existence of positive solutions for fractional q-difference equations involvi...IJRTEMJOURNAL
The existence of positive solutions is considered for a fractional q-difference equation with pLaplacian operator in this article. By employing the Avery-Henderson fixed point theorem, a new result is obtained
for the boundary value problems.
The document discusses techniques for uncertainty propagation and constructing surrogate models. It describes Monte Carlo sampling, analytic techniques, and perturbation techniques for propagating uncertainties in nonlinear models. It also discusses constructing surrogate models such as polynomial, Kriging, and Gaussian process models to approximate computationally expensive discretized partial differential equation models for applications such as Bayesian calibration and design. The document provides an example of constructing a quadratic surrogate model to approximate the response of a heat equation model.
This document discusses uncertainty propagation techniques for determining statistics of model outputs given uncertain model inputs. It covers analytic approaches for linear models, perturbation methods for nonlinear models, and direct sampling methods. It also discusses computing moments using stochastic spectral methods like stochastic Galerkin with polynomial chaos. The document provides an example of applying perturbation and sampling methods to a nonlinear oscillator model with uncertain parameters. It compares the results from both approaches to the true natural frequency. Finally, it discusses uncertainty quantification for a HIV model and the use of prediction intervals in nuclear power plant design.
Lyapunov-type inequalities for a fractional q, -difference equation involvin...IJMREMJournal
The document summarizes a research paper that presents new Lyapunov-type inequalities for a fractional boundary value problem involving a fractional difference equation with a p-Laplacian operator. The paper obtains necessary conditions for the existence of nontrivial solutions to the equation. It also presents some applications to eigenvalue problems. Key concepts from fractional calculus such as fractional derivatives and integrals are reviewed. Lemmas establishing uniqueness of solutions to related problems are also presented.
The document discusses error analysis for quasi-Monte Carlo methods used for numerical integration. It introduces the concepts of reproducing kernel Hilbert spaces and mean square discrepancy to analyze integration error. Specifically, it shows that the mean square discrepancy of randomized low-discrepancy point sets can be computed in O(n) operations, whereas the standard discrepancy requires O(n^2) operations, making randomized quasi-Monte Carlo methods more efficient for high-dimensional integration problems.
IRJET- On Certain Subclasses of Univalent Functions: An ApplicationIRJET Journal
This document presents research on certain subclasses of univalent functions. Specifically, it studies the class WR(λ,β,α,μ,θ) which consists of analytic and univalent functions with negative coefficients in the open disk, defined by the Hadamard product with the Rafid operator. The paper obtains coefficient bounds and extreme points for this class. It also examines the weighted mean, arithmetic mean, and derives some additional results for the class.
This document summarizes several cosmological models that modify the standard ΛCDM model. It describes the Friedmann equations and free parameters for models including dark energy with a constant or variable equation of state, Cardassian expansion, Chaplygin gas, Dvali-Gabadadze-Porrati brane world models, inhomogeneous Lemaître–Tolman–Bondi models, and models with corrections from Brans-Dicke gravity or quantum gravity effects. A table lists the free parameters for each model.
The document introduces the concept of a generalized dislocated quasi metric space (gdq metric space). A gdq metric is a generalization of a metric that satisfies three conditions: it is always nonnegative, equal to zero if and only if points are equal, and satisfies a generalized triangle inequality involving a binary operation. This operation must be associative, commutative, continuous, and satisfy a β-property. The document proves various properties of gdq metric spaces, including that they induce a topology, and establishes relationships between gdq metric spaces and generalized dislocated metric spaces. Fixed point theorems are also derived.
The document introduces the concept of a generalized dislocated quasi metric space (gdq metric space). A gdq metric is a generalization of a metric that satisfies three conditions: it is always nonnegative, equals 0 if and only if points are equal, and satisfies a generalized triangle inequality involving a binary operation. This operation must be associative, commutative, continuous, and satisfy a β-property. Key results proved include: a gdq limit is unique; a point is a gdq limit point of a set if balls around it intersect the set nonempty; the gdq limit points of a set form a topology; and balls defined by a gdq metric are open sets in this topology.
Hidden gates in universe: Wormholes UCEN 2017 by Dr. Ali Ovgun
Gravity at UCEN 2017: Black holes and Cosmology, November 22, 23 and 24, 2017
The meeting take place at Universidad Central de Chile.
http://www2.udec.cl/~juoliva/gravatucen2017.html
1) The document discusses instanton solutions in AdS4/CFT3 correspondence. Instantons represent exact solutions that allow probing the CFT away from the conformal vacuum.
2) For a conformally coupled scalar field, the bulk admits instanton solutions that correspond to an instability of AdS4. The boundary effective action is a 2+1 conformally coupled scalar with a φ6 interaction, representing a vacuum instability.
3) Tunneling probabilities between vacua can be computed from the instanton solutions, representing gravitational tunneling effects in the bulk and phase transitions in the boundary CFT.
The document presents a theorem on random fixed points in metric spaces. It begins with introductions to fixed point theory, random fixed point theory, and relevant definitions. The main result is Theorem 3.1, which proves that if a self-mapping E on a complete metric space X satisfies certain contraction conditions involving parameters between 0 and 1, then E has a unique fixed point. The proof constructs a Cauchy sequence that converges to the unique fixed point. The document contributes to the study of random equations and random fixed point theory, which has applications in nonlinear analysis, probability theory, and other fields.
Phase-field modeling of crystal nucleation II: Comparison with simulations an...Daniel Wheeler
This document summarizes phase-field modeling of crystal nucleation. It discusses:
1) Homogeneous nucleation models using the phase-field method and their comparison to molecular dynamics simulations and experiments for systems like nickel and Lennard-Jones argon.
2) Applications of the phase-field model to heterogeneous systems like ice-water nucleation.
3) The effects of different double-well and interpolation functions on nucleation behavior in phase-field models.
Cosmological Perturbations and Numerical SimulationsIan Huston
Talk given at Queen Mary, University of London in March 2010.
Cosmological perturbation theory is well established as a tool for
probing the inhomogeneities of the early universe.
In this talk I will motivate the use of perturbation theory and
outline the mathematical formalism. Perturbations beyond linear order
are especially interesting as non-Gaussian effects can be used to
constrain inflationary models.
I will show how the Klein-Gordon equation at second order, written in
terms of scalar field variations only, can be numerically solved.
The slow roll version of the second order source term is used and the
method is shown to be extendable to the full equation. This procedure
allows the evolution of second order perturbations in general and the
calculation of the non-Gaussianity parameter in cases where there is
no analytical solution available.
Bayesian Inference and Uncertainty Quantification for Inverse ProblemsMatt Moores
So-called “inverse” problems arise when the parameters of a physical system cannot be directly observed. The mapping between these latent parameters and the space of noisy observations is represented as a mathematical model, often involving a system of differential equations. We seek to infer the parameter values that best fit our observed data. However, it is also vital to obtain accurate quantification of the uncertainty involved with these parameters, particularly when the output of the model will be used for forecasting. Bayesian inference provides well-calibrated uncertainty estimates, represented by the posterior distribution over the parameters. In this talk, I will give a brief introduction to Markov chain Monte Carlo (MCMC) algorithms for sampling from the posterior distribution and describe how they can be combined with numerical solvers for the forward model. We apply these methods to two examples of ODE models: growth curves in ecology, and thermogravimetric analysis (TGA) in chemistry. This is joint work with Matthew Berry, Mark Nelson, Brian Monaghan and Raymond Longbottom.
Theoretical and Applied Phase-Field: Glimpses of the activities in IndiaDaniel Wheeler
1. The document summarizes recent work on phase-field modeling from several research groups in India.
2. It describes applications of phase-field modeling to spinodal decomposition, grain growth, precipitate evolution, and multi-phase solidification.
3. It highlights a recent study by the author using phase-field modeling to predict the equilibrium shapes of coherent precipitates under the influence of elastic stresses. The model accounts for elastic anisotropy and different eigenstrain configurations.
Fixed point theorems for random variables in complete metric spacesAlexander Decker
This document presents two fixed point theorems for random variables in complete metric spaces. Theorem 1 proves that if a self-mapping E on a complete metric space satisfies certain rational inequalities involving distances between random variables, then E has a fixed point. Theorem 2 proves a similar result for a self-mapping E satisfying alternative rational inequalities, assuming E is onto. Both theorems use properties of complete metric spaces and rational inequalities to show the existence of fixed points for random variables under the given conditions.
1. The document discusses linear discrete control systems and their representation in state space form. It provides the general state space equations and describes how a discrete linear system with scalar input and output can be represented in controllable canonical form or observable canonical form.
2. It also discusses linear system stability analysis using characteristics polynomials as well as analyzing stability of nonlinear systems by linearizing around an operating point.
3. Feedback control system design is discussed where a controller is designed using input from both a reference signal and system output to generate the control input.
Phase-field modeling of crystal nucleation I: Fundamentals and methodsDaniel Wheeler
This document summarizes phase-field modeling of homogeneous crystal nucleation using two main methods. The first method adds fluctuations (noise) to the phase-field equations of motion to mimic natural nucleation. The noise amplitude is determined by the fluctuation-dissipation theorem. This models nucleation without assuming a sharp interface or bulk properties. The second method places supercritical crystal seeds randomly in space and time to model nucleation. Quantitative results from both methods are difficult to obtain due to limitations of classical nucleation theory. The document outlines the phase-field model and equations used to simulate homogeneous nucleation and crystal growth in 2D with and without noise to demonstrate convergence with spatial and temporal discretization.
Stability Result of Iterative procedure in normed spaceKomal Goyal
The document summarizes the stability of Jungck-Noor iterative schemes for maps satisfying a general contractive condition in normed spaces. It defines the Jungck-Noor iterative scheme and establishes that the scheme is (S,T)-stable if S and T satisfy a contractive condition involving a monotone decreasing sequence. The proof uses previous lemmas and shows that if the iterative scheme converges to a point p, and another sequence converges to p, then the other sequence also converges to p, establishing the stability of the iterative scheme.
Numerical Approximation of Filtration Processes through Porous MediaRaheel Ahmed
In this MSc thesis, we studied numerical methods for the coupling of free fluid flow with porous medium flow. The free fluid flow is modelled by the Stokes equations while the flow in the porous medium is modelled by Darcy’s law. Appropriate conditions are imposed at the interface between the two regions. The weak formulation of the problem is based on mixed-formulation for Stokes and on a primal-mixed formulation for Darcy equation, incorporating in a natural way the interface conditions. The finite element discretization of the problem leads to large, sparse and ill-conditioned algebraic system to be solved for velocities in both domains, Stokes pressure and piezometric head in porous domain. The system is reduced to interface systems for the normal velocity and piezometric head by a Schur complement approach. We present numerical results for several solution methods based on different preconditioning techniques for the solution of the interface systems. We study the effectiveness of the preconditioners with respect to mesh refinement and physical parameters. An application to cross-flow membranes has been considered. Finally, we also assess the numerical accuracy of an uncoupled algorithm for transient problem, which uses different time steps in the Stokes and in the Darcy domains.
ON ESTIMATION OF TIME SCALES OF MASS TRANSPORT IN INHOMOGENOUS MATERIALZac Darcy
In this paper we generalized recently introduced approach of estimation of time scales of mass transport in inhomogenous materials under influence of inhomogenous potential field. Some examples of using of the approach were considered.
The document discusses triangular norm (t-norm) based kernel functions and their application to kernel k-means clustering. It introduces common kernel functions and describes how t-norms can be used to create new kernel functions. Several parameterized and non-parameterized t-norm based kernel functions are presented. The document then details experiments applying various kernel functions including t-norm kernels to four datasets, evaluating the results using adjusted rand index scores. The best performing kernels for each dataset are identified, with some t-norm kernels performing comparably or better than traditional kernels.
Stochastic differential equations (SDEs) describe systems with random components. Common methods to solve SDEs include spectral and perturbation methods. The spectral method represents variables and parameters as mean values plus fluctuations. Taking the expected value of the SDE yields equations for the mean and fluctuations that can be solved. The perturbation method expresses variables and parameters as power series expansions. Introducing these into the SDE allows analytical or numerical solution. SDEs are used to model systems with uncertain parameters like groundwater flow with random hydraulic conductivity.
A common random fixed point theorem for rational inequality in hilbert spaceAlexander Decker
This document presents a common random fixed point theorem for four continuous random operators defined on a non-empty closed subset of a separable Hilbert space. It begins with introducing basic concepts such as separable Hilbert spaces, random operators, and common random fixed points. It then defines a condition (A) that the four mappings must satisfy. The main result is Theorem 2.1, which proves the existence of a unique common random fixed point for the four operators under condition (A) and a rational inequality condition. The proof constructs a sequence of measurable functions and shows it converges to the common random fixed point. This establishes the common random fixed point theorem for these operators.
Using blurred images to assess damage in bridge structures?Alessandro Palmeri
Faster trains and augmented traffic have significantly increased the number and amplitude of loading cycles experienced on a daily basis by composite steel-concrete bridges. This higher demand accelerates the occurrence of damage in the shear connectors between the two materials, which in turn can severely affect performance and reliability of these structures. The aim of this talk is to present the preliminary results of theoretical and experimental investigations undertaken to assess the feasibility of using the envelope of deflections and rotations induced by moving loads as a practical and cost-effective alternative to traditional methods of health monitoring for composite bridges. Both analytical and numerical formulations for this dynamic problem are presented and the results of a parametric study are discussed. A novel photogrammetric approach is also introduced, which allows identifying vibration patterns in civil engineering structures by analysing blurred targets in long-exposure digital images. The initial experimental validation of this approach is presented and further challenges are highlighted.
This document summarizes several cosmological models that modify the standard ΛCDM model. It describes the Friedmann equations and free parameters for models including dark energy with a constant or variable equation of state, Cardassian expansion, Chaplygin gas, Dvali-Gabadadze-Porrati brane world models, inhomogeneous Lemaître–Tolman–Bondi models, and models with corrections from Brans-Dicke gravity or quantum gravity effects. A table lists the free parameters for each model.
The document introduces the concept of a generalized dislocated quasi metric space (gdq metric space). A gdq metric is a generalization of a metric that satisfies three conditions: it is always nonnegative, equal to zero if and only if points are equal, and satisfies a generalized triangle inequality involving a binary operation. This operation must be associative, commutative, continuous, and satisfy a β-property. The document proves various properties of gdq metric spaces, including that they induce a topology, and establishes relationships between gdq metric spaces and generalized dislocated metric spaces. Fixed point theorems are also derived.
The document introduces the concept of a generalized dislocated quasi metric space (gdq metric space). A gdq metric is a generalization of a metric that satisfies three conditions: it is always nonnegative, equals 0 if and only if points are equal, and satisfies a generalized triangle inequality involving a binary operation. This operation must be associative, commutative, continuous, and satisfy a β-property. Key results proved include: a gdq limit is unique; a point is a gdq limit point of a set if balls around it intersect the set nonempty; the gdq limit points of a set form a topology; and balls defined by a gdq metric are open sets in this topology.
Hidden gates in universe: Wormholes UCEN 2017 by Dr. Ali Ovgun
Gravity at UCEN 2017: Black holes and Cosmology, November 22, 23 and 24, 2017
The meeting take place at Universidad Central de Chile.
http://www2.udec.cl/~juoliva/gravatucen2017.html
1) The document discusses instanton solutions in AdS4/CFT3 correspondence. Instantons represent exact solutions that allow probing the CFT away from the conformal vacuum.
2) For a conformally coupled scalar field, the bulk admits instanton solutions that correspond to an instability of AdS4. The boundary effective action is a 2+1 conformally coupled scalar with a φ6 interaction, representing a vacuum instability.
3) Tunneling probabilities between vacua can be computed from the instanton solutions, representing gravitational tunneling effects in the bulk and phase transitions in the boundary CFT.
The document presents a theorem on random fixed points in metric spaces. It begins with introductions to fixed point theory, random fixed point theory, and relevant definitions. The main result is Theorem 3.1, which proves that if a self-mapping E on a complete metric space X satisfies certain contraction conditions involving parameters between 0 and 1, then E has a unique fixed point. The proof constructs a Cauchy sequence that converges to the unique fixed point. The document contributes to the study of random equations and random fixed point theory, which has applications in nonlinear analysis, probability theory, and other fields.
Phase-field modeling of crystal nucleation II: Comparison with simulations an...Daniel Wheeler
This document summarizes phase-field modeling of crystal nucleation. It discusses:
1) Homogeneous nucleation models using the phase-field method and their comparison to molecular dynamics simulations and experiments for systems like nickel and Lennard-Jones argon.
2) Applications of the phase-field model to heterogeneous systems like ice-water nucleation.
3) The effects of different double-well and interpolation functions on nucleation behavior in phase-field models.
Cosmological Perturbations and Numerical SimulationsIan Huston
Talk given at Queen Mary, University of London in March 2010.
Cosmological perturbation theory is well established as a tool for
probing the inhomogeneities of the early universe.
In this talk I will motivate the use of perturbation theory and
outline the mathematical formalism. Perturbations beyond linear order
are especially interesting as non-Gaussian effects can be used to
constrain inflationary models.
I will show how the Klein-Gordon equation at second order, written in
terms of scalar field variations only, can be numerically solved.
The slow roll version of the second order source term is used and the
method is shown to be extendable to the full equation. This procedure
allows the evolution of second order perturbations in general and the
calculation of the non-Gaussianity parameter in cases where there is
no analytical solution available.
Bayesian Inference and Uncertainty Quantification for Inverse ProblemsMatt Moores
So-called “inverse” problems arise when the parameters of a physical system cannot be directly observed. The mapping between these latent parameters and the space of noisy observations is represented as a mathematical model, often involving a system of differential equations. We seek to infer the parameter values that best fit our observed data. However, it is also vital to obtain accurate quantification of the uncertainty involved with these parameters, particularly when the output of the model will be used for forecasting. Bayesian inference provides well-calibrated uncertainty estimates, represented by the posterior distribution over the parameters. In this talk, I will give a brief introduction to Markov chain Monte Carlo (MCMC) algorithms for sampling from the posterior distribution and describe how they can be combined with numerical solvers for the forward model. We apply these methods to two examples of ODE models: growth curves in ecology, and thermogravimetric analysis (TGA) in chemistry. This is joint work with Matthew Berry, Mark Nelson, Brian Monaghan and Raymond Longbottom.
Theoretical and Applied Phase-Field: Glimpses of the activities in IndiaDaniel Wheeler
1. The document summarizes recent work on phase-field modeling from several research groups in India.
2. It describes applications of phase-field modeling to spinodal decomposition, grain growth, precipitate evolution, and multi-phase solidification.
3. It highlights a recent study by the author using phase-field modeling to predict the equilibrium shapes of coherent precipitates under the influence of elastic stresses. The model accounts for elastic anisotropy and different eigenstrain configurations.
Fixed point theorems for random variables in complete metric spacesAlexander Decker
This document presents two fixed point theorems for random variables in complete metric spaces. Theorem 1 proves that if a self-mapping E on a complete metric space satisfies certain rational inequalities involving distances between random variables, then E has a fixed point. Theorem 2 proves a similar result for a self-mapping E satisfying alternative rational inequalities, assuming E is onto. Both theorems use properties of complete metric spaces and rational inequalities to show the existence of fixed points for random variables under the given conditions.
1. The document discusses linear discrete control systems and their representation in state space form. It provides the general state space equations and describes how a discrete linear system with scalar input and output can be represented in controllable canonical form or observable canonical form.
2. It also discusses linear system stability analysis using characteristics polynomials as well as analyzing stability of nonlinear systems by linearizing around an operating point.
3. Feedback control system design is discussed where a controller is designed using input from both a reference signal and system output to generate the control input.
Phase-field modeling of crystal nucleation I: Fundamentals and methodsDaniel Wheeler
This document summarizes phase-field modeling of homogeneous crystal nucleation using two main methods. The first method adds fluctuations (noise) to the phase-field equations of motion to mimic natural nucleation. The noise amplitude is determined by the fluctuation-dissipation theorem. This models nucleation without assuming a sharp interface or bulk properties. The second method places supercritical crystal seeds randomly in space and time to model nucleation. Quantitative results from both methods are difficult to obtain due to limitations of classical nucleation theory. The document outlines the phase-field model and equations used to simulate homogeneous nucleation and crystal growth in 2D with and without noise to demonstrate convergence with spatial and temporal discretization.
Stability Result of Iterative procedure in normed spaceKomal Goyal
The document summarizes the stability of Jungck-Noor iterative schemes for maps satisfying a general contractive condition in normed spaces. It defines the Jungck-Noor iterative scheme and establishes that the scheme is (S,T)-stable if S and T satisfy a contractive condition involving a monotone decreasing sequence. The proof uses previous lemmas and shows that if the iterative scheme converges to a point p, and another sequence converges to p, then the other sequence also converges to p, establishing the stability of the iterative scheme.
Numerical Approximation of Filtration Processes through Porous MediaRaheel Ahmed
In this MSc thesis, we studied numerical methods for the coupling of free fluid flow with porous medium flow. The free fluid flow is modelled by the Stokes equations while the flow in the porous medium is modelled by Darcy’s law. Appropriate conditions are imposed at the interface between the two regions. The weak formulation of the problem is based on mixed-formulation for Stokes and on a primal-mixed formulation for Darcy equation, incorporating in a natural way the interface conditions. The finite element discretization of the problem leads to large, sparse and ill-conditioned algebraic system to be solved for velocities in both domains, Stokes pressure and piezometric head in porous domain. The system is reduced to interface systems for the normal velocity and piezometric head by a Schur complement approach. We present numerical results for several solution methods based on different preconditioning techniques for the solution of the interface systems. We study the effectiveness of the preconditioners with respect to mesh refinement and physical parameters. An application to cross-flow membranes has been considered. Finally, we also assess the numerical accuracy of an uncoupled algorithm for transient problem, which uses different time steps in the Stokes and in the Darcy domains.
ON ESTIMATION OF TIME SCALES OF MASS TRANSPORT IN INHOMOGENOUS MATERIALZac Darcy
In this paper we generalized recently introduced approach of estimation of time scales of mass transport in inhomogenous materials under influence of inhomogenous potential field. Some examples of using of the approach were considered.
The document discusses triangular norm (t-norm) based kernel functions and their application to kernel k-means clustering. It introduces common kernel functions and describes how t-norms can be used to create new kernel functions. Several parameterized and non-parameterized t-norm based kernel functions are presented. The document then details experiments applying various kernel functions including t-norm kernels to four datasets, evaluating the results using adjusted rand index scores. The best performing kernels for each dataset are identified, with some t-norm kernels performing comparably or better than traditional kernels.
Stochastic differential equations (SDEs) describe systems with random components. Common methods to solve SDEs include spectral and perturbation methods. The spectral method represents variables and parameters as mean values plus fluctuations. Taking the expected value of the SDE yields equations for the mean and fluctuations that can be solved. The perturbation method expresses variables and parameters as power series expansions. Introducing these into the SDE allows analytical or numerical solution. SDEs are used to model systems with uncertain parameters like groundwater flow with random hydraulic conductivity.
A common random fixed point theorem for rational inequality in hilbert spaceAlexander Decker
This document presents a common random fixed point theorem for four continuous random operators defined on a non-empty closed subset of a separable Hilbert space. It begins with introducing basic concepts such as separable Hilbert spaces, random operators, and common random fixed points. It then defines a condition (A) that the four mappings must satisfy. The main result is Theorem 2.1, which proves the existence of a unique common random fixed point for the four operators under condition (A) and a rational inequality condition. The proof constructs a sequence of measurable functions and shows it converges to the common random fixed point. This establishes the common random fixed point theorem for these operators.
Using blurred images to assess damage in bridge structures?Alessandro Palmeri
Faster trains and augmented traffic have significantly increased the number and amplitude of loading cycles experienced on a daily basis by composite steel-concrete bridges. This higher demand accelerates the occurrence of damage in the shear connectors between the two materials, which in turn can severely affect performance and reliability of these structures. The aim of this talk is to present the preliminary results of theoretical and experimental investigations undertaken to assess the feasibility of using the envelope of deflections and rotations induced by moving loads as a practical and cost-effective alternative to traditional methods of health monitoring for composite bridges. Both analytical and numerical formulations for this dynamic problem are presented and the results of a parametric study are discussed. A novel photogrammetric approach is also introduced, which allows identifying vibration patterns in civil engineering structures by analysing blurred targets in long-exposure digital images. The initial experimental validation of this approach is presented and further challenges are highlighted.
A common unique random fixed point theorem in hilbert space using integral ty...Alexander Decker
This document presents a common unique random fixed point theorem for two continuous random operators defined on a non-empty closed subset of a Hilbert space.
The theorem proves that if two continuous random operators S and T satisfy a certain integral type condition (Condition A), then S and T have a unique common random fixed point.
The proof constructs a sequence of measurable functions {ng} and shows that it converges to the common unique random fixed point of S and T. It utilizes a rational inequality and the parallelogram law to show {ng} is a Cauchy sequence that converges, and its limit is the random fixed point.
Doubly Accelerated Stochastic Variance Reduced Gradient Methods for Regulariz...Tomoya Murata
This document summarizes a new method for solving regularized empirical risk minimization problems in mini-batch settings. The proposed method, called Doubly Accelerated Stochastic Variance Reduced Gradient, combines inner and outer acceleration to improve the mini-batch efficiency of previous methods like SVRG and AccProxSVRG. It achieves this by applying Nesterov's acceleration both within and across iterations of the AccProxSVRG algorithm. Numerical experiments demonstrate that the new method requires a smaller mini-batch size to achieve a given optimization error compared to prior methods.
Modeling the Dynamics of SGD by Stochastic Differential EquationMark Chang
1) Start with a small learning rate and large batch size to find a flat minimum with good generalization. 2) Gradually increase the learning rate and decrease the batch size to find sharper minima that may improve training accuracy. 3) Monitor both training and validation/test accuracy - similar accuracy suggests good generalization while different accuracy indicates overfitting.
Trilinear embedding for divergence-form operatorsVjekoslavKovac1
The document discusses a trilinear embedding theorem for divergence-form operators with complex coefficients. It proves that if matrices A, B, C are appropriately p,q,r-elliptic, then there is a bound on the integral of the product of the gradients of the semigroups associated with the operators. The proof uses a Bellman function technique and shows the relationship to the concept of p-ellipticity. It generalizes previous work on bilinear embeddings to the trilinear case.
1. The document discusses characteristic time scales and approximations for time-dependent transport phenomena problems, including the quasi-steady state approximation (QSSA) and penetration approximation.
2. It uses the example of diffusion through a membrane pore to illustrate the QSSA and penetration solutions. For the QSSA, it assumes concentrations equilibrate rapidly within the pore. For the penetration approximation, it assumes the pore length is effectively infinite at short times.
3. It also covers regular perturbation techniques, where a small parameter is introduced and solutions are found order-by-order in the parameter. An example of heat transfer along a heated wire is presented.
Phase diagram at finite T & Mu in strong coupling limit of lattice QCDBenjamin Jaedon Choi
This document summarizes the derivation of an effective free energy for QCD at strong coupling using a mean field approximation with 1 flavor staggered fermion. Key steps include:
1) Performing a path integral over spatial link variables to obtain quark propagators.
2) Introducing auxiliary bosonic fields using a Hubbard-Stratonovich transformation to obtain a bilinear form in quark fields.
3) Applying a mean field approximation to the auxiliary fields.
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Harnessing WebAssembly for Real-time Stateless Streaming Pipelines
Stationary Incompressible Viscous Flow Analysis by a Domain Decomposition Method
1. Stationary Incompressible
Viscous Flow Analysis by a
Domain Decomposition Method
Hiroshi Kanayama, Daisuke
Tagami
and Masatsugu Chiba
( Kyushu University )
2. Contents
Introduction
Formulations
Iterative Domain Decomposition Method
for Stationary Flow Problems
Numerical Examples
1 million DOF cavity flow, DDM v.s.
FEM
A concrete example
Conclusions
3. Objectives
In finite element analysis for stationary
flow problems, our objectives are to
analyze large scale (10-100 million
DOF) problems.
Why Iterative DDM ?
HDDM is effective.
Ex. Structural analysis ( 100 million DOF:
1999 R.Shioya and G.Yagawa )
4. Formulations
Stationary Navier-Stokes Equations
Weak Form
Newton Method
Finite Element Approximation
Stabilized Finite Element Method
Domain Decomposition Method
17. (g) Convergence check for . If converged
, If not converged go to (h) .
(h) Compue .
(3) Construction of solution .
(a) Solve .
);(
;
),(
),(
)()()()()1()1(
)()0(
)1()0(
)(
)(
)(
kkkkkk
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k
k
k
k
Swwgw
gg
gg
ςγ
ς
ρ
γ
−+=
⋅=
++
+
[ ]{ } ;**
i
T
tbiitibii faaaKKK =
)1( +k
g
)1(* +
= k
bb aa
)1()(
, +kk
wγ
*
ia
18. Preconditioned BiCGSTAB for the Interface Problem
end
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:dountil,,for
,set,,guessinitialanis
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)()(
)()()()(
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+
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=
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≤=
=−=
ς
ρ
γ
ς
ςρλλ
ς
ρ
ρ
ςγ
γχλ
19. GPBiCG for the Interface Problem (1/2)
),
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then,if(
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),)(,(),)(,(
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begin
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,,0set,χ,guessinitialanisλ
)(
)()(
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)()()()()()()()(
)()()()()()()()(
)(
)()()()()()()()(
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)(
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)()(
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00
10
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0
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0
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===
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=
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≤=
===−=
−−
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−−−
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kk
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k
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η
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α
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20. GPBiCG for the Interface Problem (2/2)
end
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+=
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−+=
+−+=
+
+
+
−
−−−
0
10
1
1
1
111
22. [ ]{ } ;)()(
i
T
tbiitibii faaaKKK =00
[ ]{ }
;
;
)()(
)()()(
00
000
gp
faaaKKKg b
T
tbibtbbbi
=
−=
GPBiCG
(1) Initialization
(a) Set .
(b) Solve .
(c) Set and .
)(0
ba
)(0
ia
)(0
g )(0
p
26. (h) Convergence check for . If converged
If not converged go to (h) .
(i) Compute .
(3) Construction of solution .
(a) Solve .
[ ]{ } ;**
i
T
tbiitibii faaaKKK =
)1( +k
g
)()()(
,, 11 ++ kkk
pwβ
*
ia
),(
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)()()()(
)()(
)()(
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gg
gg
−+=
+=
⋅=
++
+
β
β
ς
α
β
11
0
10
,λλ )()()()()(* kkkkk
b zpa −−== +
α1
27. Preconditioned GPBiCG for the Interface Problem (1/2)
),
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then,if(
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),)(,(),)(,(
,
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),)(,(),)(,(
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begin
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,,0set,χλ,guessinitialanisλ
)(
)()(
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)(
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00
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1111
1111
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111
11
0
0
1111
0
111000
===
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−−−
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−−−
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ytSMtSMyyytSMtSM
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Spgt
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upgMp
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wtSg
ης
η
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α
α
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β
β
28. Preconditioned GPBiCG for the Interface Problem (2/2)
end
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zpλλ
uzgMz
ugMtMSpMu
β
ς
α
β
ςη
α
αης
βης
+=
⋅=
−−=
−−=
−+=
+−+=
−
+
−+
+
−−
−−−−−−
1
0
10
11
1
11
111111
29. One More Analysis of Subdomains
Output Results
Read Data
Analyze Analyze Analyze
Converged?
Change B.C.
Yes
No
System Flowchart
Skyline Method
BiCGSTAB Method
Newton Method
40. 9 hours (BiCGSTAB)→ 1 hour 40 min.(GPBiCG)
GPBiCG is a liitle faster than BiCGSTAB for small problems
High Reynolds number problems are not solved.
Strong preconditioners may be required.
41. ( 2 parts , 2*75 subdomains, 800 DOF/subdomain≒
Total DOF : 119,164
Interface DOF : 42,417
Domain Decomposition
42. Initial : Sol. of Stokes
Criterion : 4E0.1)0()()1(
−<−
∞∞
+
uuu nn
Iteration counts of
Newton method
収束履歴( Newton 法)
1.00E- 06
1.00E- 05
1.00E- 04
1.00E- 03
1.00E- 02
1.00E- 01
1.00E+00
0 1 2 3 4 5
反復回数
相対変化量
HDDM FEM
47. he Vector Diagram and the Pressure Contour-Line on x2 = 0.5 ( Re:1
DDM(1) DDM(2) FEM
48. Comparison of the
Velocity ( Re:100 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
- 0.2 0 0.2 0.4 0.6 0.8 1
x1 c ompone nt of ve loc ity
x3
DDM(1) DDM(2) FEM
49. Relative Residual History
of Newton Method
( Re:100 )
1.00E- 09
1.00E- 08
1.00E- 07
1.00E- 06
1.00E- 05
1.00E- 04
1.00E- 03
0 1 2 3 4
No. of Ite rations
RelativeResidual
DDM(1) DDM(2) FEM
51. Comparison of the
Velocity ( Re:1000 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
- 0.2 0 0.2 0.4 0.6 0.8 1
x1 c ompone nt of ve loc ity
x3
DDM(1) DDM(2) FEM
52. Relative Residual History
of Newton Method
( Re:1000 )
1.00E- 08
1.00E- 07
1.00E- 06
1.00E- 05
1.00E- 04
1.00E- 03
0 1 2 3 4 5 6
No. of Ite rations
RelativeResidual
DDM(1) DDM(2) FEM
53. A subway station model
Constant flows
the natural boundary condition
55. Convergence Criteria
5)0(
2
)0()(
2
)(
100.1 −
×≤gg
nk
Convergence of Newton method
4)1()()1(
100.1 −
∞
+
∞
+
×≤− nnn
aaa
Convergence of the interface problem
with GPBiCG method
Initial values of the interface problem
with GPBiCG method
( )
=
=
0
0,0,0
pλ
λu
The solution of the previous step
• 0 step of Newton method
• other steps of Newton method
60. Conclusion
Future Works
A HDDM computing system for
stationary Navier-Stokes problems
has been developed and applied to
1- 10 million problems successfully.
More larger scale analysis based on
strong preconditioners and applications to high
Reynolds number problems and coupled problems