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An efficient numerical algorithm for solving viscosity contrast Cahn-Hilliard-Navier-Stokes system in porous media

JOURNAL OF COMPUTATIONAL PHYSICS 2020年 400卷 108948-000页

作者： Liu, Chen Frank, Florian Thiele, Christopher Alpak, Faruk O. Berg, Steffen Chapman, Walter Riviere, Beatrice Rice Univ Dept Computat & Appl Math 6100 Main St Houston TX 77005 USA Friedrich Alexander Univ Erlangen Nurnberg Dept Math Cauerstr 11 D-91058 Erlangen Germany Shell Technol Ctr 3333 Highway 6 South Houston TX 77082 USA Shell Global Solut Int BV Grasweg 31 NL-1031 HW Amsterdam Netherlands Rice Univ Dept Chem & Biomol Engn 6100 Main St Houston TX 77005 USA

Two-phase flow with viscosity contrast at the pore scale is modeled by a time-dependent Cahn-Hilliard-Navier-Stokes model and belongs to the class of diffuse interface method. The model allows for moving contact line and varying wettability. The numerical scheme utilizes an efficient pressure-correction projection algorithm, in conjunction with interior penalty discontinuous Galerkin schemes for space discretization developed within the framework of a distributed parallel pore-scale flow simulation system. The effect of viscosity contrast on the phase distribution is studied in relation with capillary forces and wettability. The algorithm is numerically robust and lends itself naturally to large-scale 3D numerical simulations. (C) 2019 Elsevier Inc. All rights reserved.

关键词： Cahn-Hilliard-Navier-Stokes Discontinuous Galerkin methods projection algorithm Viscosity ratio Contact angle Micro-CT images

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Sparsity-Exploiting Distributed projections onto a Simplex

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INFORMS JOURNAL ON COMPUTING 2024年第3期36卷 820-835页

作者： Dai, Yongzheng Chen, Chen Ohio State Univ Integrated Syst Engn Columbus OH 43210 USA

Projecting a vector onto a simplex is a well-studied problem that arises in a wide range of optimization problems. Numerous algorithms have been proposed for determining the projection;however, the primary focus of the literature is on serial algorithms. We present a parallel method that decomposes the input vector and distributes it across multiple processors for local projection. Our method is especially effective when the resulting projection is highly sparse, which is the case, for instance, in large-scale problems with independent and identically distributed (i.i.d.) entries. Moreover, the method can be adapted to parallelize a broad range of serial algorithms from the literature. We fill in theoretical gaps in serial algorithm analysis and develop similar results for our parallel analogues. Numerical experiments conducted on a wide range of large-scale instances, both real world and simulated, demonstrate the practical effectiveness of the method.

关键词： simplex parallel algorithm projection algorithm

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Deployment and Configuration of Applications for Ambient Systems

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Procedia Computer Science 2015年 52卷 373-380页

作者： Ferdinand Piette Cédric Dinont Amal El Fallah Seghrouchni Patrick Taillibert Université Pierre et Marie Curie Paris France Institut Supérieur de l’Électronique et du Numérique Lille France

Ambient Intelligence (AmI) provides a vision of the information society where heterogeneous hardware entities are disseminated in the environment and used by intelligent agents to provide ubiquitous applications. To ease the integration of new entities in the system, the application and the underlying hardware infrastructure have to be decorrelated. The aim of our research work is to propose mechanisms for the deployment, automatic configuration and monitoring of applications on an heterogeneous hardware infrastructure. In this paper, we model ambient systems to fulfill this purpose. We propose a graph-based mathematical model for ambient systems. This model allows to use a projection algorithm, extending an existing graph matching algorithm, for the deployment and the automatic configuration of applications on an heterogeneous hardware infrastructure.

关键词： Ambient Intelligence Graph homomorphism projection algorithm Heterogeneous systems

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Exponential Stability for Adaptive Control of a Class of First-Order Nonlinear Systems

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IFAC-PapersOnLine 2019年第29期52卷 168-173页

作者： Mohamad T. Shahab Daniel E. Miller Dept. of Electrical and Computer Engineering University of Waterloo Waterloo ON Canada N2L 3G1

In adaptive control it is typically proven that a weak asymptotic form of stability holds; furthermore, at best it is proven that a bounded noise yields a bounded state. Recently, however, it has been proven in a variety of scenarios that it is possible to carry out adaptive control for a linear-time invariant (LTI) discrete-time plant so that the closed-loop system enjoys exponential stability, a bounded gain on the noise, as well as a convolution bound on the effect of the exogenous inputs; the key idea is to carry out parameter estimation by using the ideal projection algorithm in conjunction with restricting the parameter estimates to a convex set. In this paper we extend the approach to a class of first-order nonlinear systems.

关键词： Adaptive Control Nonlinear systems Exponential stability projection algorithm

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Discrete Adaptive Repetitive Control: Convergence Analysis and Implementation

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Acta Automatica Sinica 2013年第4期39卷 400-406页

作者： Ming-Xuan SUN Lin-Jiang YU Hai-Gang HE College of Information Engineering Zhejiang University of Technology Hangzhou 310023 China

This paper presents an adaptive repetitive control method for discrete periodically time-varying systems with known periodicity. When estimating unknowns, a repetitive learning projection algorithm with dead-zone is used. The result in this paper can be considered an application of the key technique lemma in repetition domain, by which stability and convergence of the discrete adaptive repetitive control system are established. It is shown that both system input and output are bounded and the tracking error would converge to the bound on the disturbance variable. A linear motor servo system is taken as an example, and experiment results are presented for demonstrating effectiveness of the proposed method.

关键词： Adaptive repetitive control projection algorithm dead-zone modification discrete-time periodic systems

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Adaptive desired velocity field control for cooperative mobile robotic systems with decentralized PVFC

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JSME INTERNATIONAL JOURNAL SERIES C-MECHANICAL SYSTEMS MACHINE ELEMENTS AND MANUFACTURING 2004年第1期47卷 280-288页

作者： Suh, JH Yamakita, M Kim, SB Dong A Univ NRL Div Elect Elect & Comp Engn Pusan South Korea Tokyo Inst Technol Dept Mech & Syst Engn Meguro Ku Tokyo Japan Pukyong Natl Univ Sch Mech Engn Pusan South Korea

Passive velocity field control (PVFC) was previously developed for mechanical systems which have strong coordination and must interact with the physical environment. Moreover, In our previous researches, the extended PVFC algorithm for multiple manipulator systems is also introduced. The methodology of PVFC and extended PVFC encode tasks using time invariant desired velocity fields instead of the more traditional method of time trajectories and guarantees that the closed loop system behave passively with environment power as the supply rate. This paper addresses an adaptive generation method of the desired velocity field for cooperative mobile robots with decentralized PVFC. Of course, this paper is a method of decentralized control algorithm for cooperative mobile robot systems handling a common object in a coordinated way. The proposed control method for cooperative mobile robots in constructed based on the extended PVFC in this paper. Moreover the stability and the boundedness are ensured using projection algorithm. Finally the effectiveness of proposed control method is examined by numerical simulation for cooperation tasks with two 3-wheeled mobile robot systems to consider our previous research.

关键词： nonholonomic adaptive control passive velocity field control (PVFC) passivity cooperative mobile robot decentralized control projection algorithm

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Adaptive control of a class of discrete-time nonlinear systems yielding linear-like behavior

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AUTOMATICA 2021年 130卷 109691-109691页

作者： Shahab, Mohamad T. Miller, Daniel E. King Abdullah Univ Sci & Technol KAUST Robot Intelligent Syst & Control RISC Lab Elect & Math Sci & Engn CEMSE Div Thuwal 23955 Saudi Arabia Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada

In adaptive control it is typically proven that an asymptotic form of stability holds, and that at best a bounded-noise bounded-state property is proven. Recently, however, it has been proven in a variety of scenarios that it is possible to carry out adaptive control for a linear time-invariant (LTI) discrete-time plant so that the closed-loop system enjoys linear-like behavior: exponential stability, a bounded noise gain, and a convolution bound on the exogenous signals;the key idea is to carry out parameter estimation by using the original projection algorithm together with restricting the parameter estimates to a convex set. In this paper, we extend this approach to a class of nonlinear plants and show how to carry out adaptive control so that we obtain the same desirable linear-like closed-loop properties. First, we consider plants with a known sign of the control gain;second, we consider the case when that sign is unknown, where two parameter estimators and a simple switching mechanism are used. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Adaptive control Nonlinear systems Exponential stability Switching adaptive control projection algorithm

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A Bi-level Formulation for the Combined Dynamic Equilibrium based Traffic Signal Control

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Procedia - Social and Behavioral Sciences 2013年 80卷 729-752页

作者： Satish Ukkusuri Kien Doan H.M. Abdul Aziz School of Civil Engineering Purdue University West Lafayette Indiana 47907–2051

This paper formulates the combined dynamic user equilibrium and signal control problem (DUESC) as a bi-level optimization problem. The signal control operator in the upper level optimizes the signal setting to minimize the system travel time whereas the road users in the lower level minimize their own costs (by changing departure times, paths or both) leading to dynamic user equilibrium behavior. Three components of the bi-level formulation are discussed including network loading model, the dynamic user equilibrium model and the signal control model. Then the combined problems are formulated as a Nash-Cournot game and a Stackelberg game. A solution technique based on the iterative optimization and assignment (IOA) method is proposed to solve the DUESC problem. We use the projection algorithm to solve the lower level and the mixed integer programming solver to solve the upper level. Extensive numerical results demonstrate the benefits of using this model.

关键词： Dynamic user equilibrium Signal control optimization Nash-Cournot game Stackelberg game Mixed integer program projection algorithm

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Frequency Determination in Control Applications: Excitation Based Approach

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IFAC Proceedings Volumes 2012年第13期45卷 45-50页

作者： Alexander Stotsky Signals & Systems Chalmers University of Technology Gothenburg SE-412 96 Sweden

New algorithms for estimation of the frequencies of oscillating waveform signals are described. Model of the signals is presented in the form of linear difference equation with unknown coefficients, which define the frequencies and amplitudes. Coefficients are estimated utilizing the property of the persistence of excitation of oscillating signals. Exponentially damped and oscillating signals are described in a unified framework. A property of excitation is proved for exponentially damped signal that contains a single frequency via diagonal dominance of an information matrix. Two applications of this frequency estimation technique are considered. The first one is filtering of the wind speed signal in wind turbine control applications, and the second one is the frequency estimation of exponentially damped signal motivated by the engine knock detection applications.

关键词： Frequency estimation Persistence of excitation Strictly diagonally dominant matrix Exponentially damped signal projection algorithm Wind speed model Engine knock frequency

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Short-term photovoltaic power probability forecasting based on OLPP-GPR and modified clearness index

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The Journal of Engineering 2017年第13期2017卷 1625-1628页

作者： Li Fen Li Chunyang Yang Yong Yan Quanquan Zhao Jinbin Wang Lijuan College of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 People's Republic of China Maintenance Company of SMEPC Shanghai 200063 People's Republic of China Hubei Provincial Meteorological Service Center Wuhan 430205 People's Republic of China

It is important for improving the prediction accuracy of short-term output of grid-connected photovoltaic (PV) systems for improving the safety, stability, and economic operation of power system. A short-term PV power probability forecasting method based on Gaussian process regression (GPR) is proposed under this study. This method classifies the weather type into five categories according to the modified clearness index proposed by Perez et al. Then, the orthogonal locality preserving projection (OLPP) algorithm is used to extract the feature vectors of meteorological variables. Based on the extracted feature vectors of meteorological variables, establish GPR model under different weather types, which were compared with the adaboost-BP neural network. The simulation results show that OLPP-GPR based on modified clearness index can be utilised to accurately predict PV power.

关键词： load forecasting regression analysis Gaussian processes power engineering computing backpropagation feature extraction neural nets photovoltaic power systems power systems vectors meteorology modified clearness index OLPP-GPR photovoltaic systems power system short-term PV power probability forecasting method Gaussian process regression weather type projection algorithm meteorological variables GPR model feature vector extraction short-term photovoltaic power probability forecasting PV systems orthogonal locality preserving projection

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