Results for "Eric T. Chung"

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Adaptive generalized multiscale finite element methods for H(curl)-elliptic problems with heterogeneous coefficientsFeb 08 2018In this paper, we construct an adaptive multiscale method for solving H(curl)-elliptic problems in highly heterogeneous media. Our method is based on the generalized multiscale finite element method. We will first construct a suitable snapshot space, ... More
Constraint Energy Minimizing Generalized Multiscale Finite Element Method for high-contrast linear elasticity problemSep 11 2018In this paper, we consider the offline and online Constraint Energy Minimizing Generalized Mul- tiscale Finite Element Method (CEM-GMsFEM) for high-contrast linear elasticity problem. Offline basis construction starts with an auxiliary multiscale space ... More
An analysis of the NLMC upscaling method for high contrast problemsApr 25 2019In this paper we propose simple multiscale basis functions with constraint energy minimization to solve elliptic problems with high contrast medium. Our methodology is based on the recently developed non-local multicontinuum method (NLMC). The main ingredient ... More
An adaptive GMsFEM for high-contrast flow problemsSep 24 2013In this paper, we derive an a-posteriori error indicator for the Generalized Multiscale Finite Element Method (GMsFEM) framework. This error indicator is further used to develop an adaptive enrichment algorithm for the linear elliptic equation with multiscale ... More
Residual driven online mortar mixed finite element methods and applicationsOct 04 2017In this paper, we develop an online basis enrichment method with the mortar mixed finite element method, using the oversampling technique, to solve for flow problems in highly heterogeneous media. We first compute a coarse grid solution with a certain ... More
A conservative local multiscale model reduction technique for Stokes flows in heterogeneous perforated domainsAug 25 2016In this paper, we present a new multiscale model reduction technique for the Stokes flows in heterogeneous perforated domains. The challenge in the numerical simulations of this problem lies in the fact that the solution contains many multiscale features ... More
An enriched multiscale mortar space for high contrast flow problemsSep 08 2016Mortar methods are widely used techniques for discretizations of partial differential equations and preconditioners for the algebraic systems resulting from the discretizations. For problems with high contrast and multiple scales, the standard mortar ... More
Mixed GMsFEM for the simulation of waves in highly heterogeneous mediaSep 08 2015Numerical simulations of waves in highly heterogeneous media have important applications, but direct computations are prohibitively expensive. In this paper, we develop a new generalized multiscale finite element method with the aim of simulating waves ... More
Generalized Multiscale Finite Element Method for Elasticity EquationsAug 25 2014In this paper, we discuss the application of Generalized Multiscale Finite Element Method (GMsFEM) to elasticity equation in heterogeneous media. Our applications are motivated by elastic wave propagation in subsurface where the subsurface properties ... More
A two-grid preconditioner with an adaptive coarse space for flow simulations in highly heterogeneous mediaJul 19 2018In this paper, we consider flow simulation in highly heterogeneous media that has many practical applications in industry. To enhance mass conservation, we write the elliptic problem in a mixed formulation and introduce a robust two-grid preconditioner ... More
An embedded SDG method for the convection-diffusion equationJun 18 2018In this paper, we present an embedded staggered discontinuous Galerkin method for the convection-diffusion equation. The new method combines the advantages of staggered discontinuous Galerkin (SDG) and embedded discontinuous Galerkin (EDG) method, and ... More
Online mixed multiscale finite element method with oversampling and its applicationsJul 02 2018In this paper, we consider an online basis enrichment mixed generalized multiscale method with oversampling, for solving flow problems in highly heterogeneous porous media. This is an exten- sion of the online mixed generalized multiscale method [6]. ... More
Online adaptive basis enrichment for mixed CEM-GMsFEMOct 25 2018Nov 16 2018In this paper, an online basis construction for constraint energy minimizing generalized multiscale finite element method (CEM-GMsFEM) in mixed formulation is proposed. The online approach is based on the strategy of oversampling and makes use of the ... More
Mixed Generalized Multiscale Finite Element Methods and ApplicationsJun 04 2014In this paper, we present a mixed Generalized Multiscale Finite Element Method (GMsFEM) for solving flow in heterogeneous media. Our approach constructs multiscale basis functions following a GMsFEM framework and couples these basis functions using a ... More
Constrained energy minimization based upscaling for coupled flow and mechanicsMay 23 2018Oct 03 2018In this paper, our aim is to present (1) an embedded fracture model (EFM) for coupled flow and mechanics problem based on the dual continuum approach on the fine grid and (2) an upscaled model for the resulting fine grid equations. The mathematical model ... More
Fast Online Generalized Multiscale Finite Element Method using Constraint Energy MinimizationJun 21 2017Local multiscale methods often construct multiscale basis functions in the offline stage without taking into account input parameters, such as source terms, boundary conditions, and so on. These basis functions are then used in the online stage with a ... More
Re-iterated multiscale model reduction using the GMsFEMJun 18 2016Numerical homogenization and multiscale finite element methods construct effective properties on a coarse grid by solving local problems and extracting the average effective properties from these local solutions. In some cases, the solutions of local ... More
An online generalized multiscale discontinuous Galerkin method (GMsDGM) for flows in heterogeneous mediaApr 17 2015Offline computation is an essential component in most multiscale model reduction techniques. However, there are multiscale problems in which offline procedure is insufficient to give accurate representations of solutions, due to the fact that offline ... More
An adaptive dynamically low-dimensional approximation method for multiscale stochastic diffusion equationsDec 04 2018Feb 03 2019In this paper, we propose a dynamically low-dimensional approximation method to solve a class of time-dependent multiscale stochastic diffusion equations. A dynamically bi-orthogonal (DyBO) method was developed to explore low-dimensional structures of ... More
Generalized Multiscale Finite Element Methods for problems in perforated heterogeneous domainsJan 14 2015Complex processes in perforated domains occur in many real-world applications. These problems are typically characterized by physical processes in domains with multiple scales (see Figure 1 for the illustration of a perforated domain). Moreover, these ... More
A staggered discontinuous Galerkin method for a class of nonlinear elliptic equationsOct 07 2016In this paper, we present a staggered discontinuous Galerkin (SDG) method for a class of nonlinear elliptic equations in two dimensions. The SDG methods have some distinctive advantages, and have been successfully applied to a wide range of problems including ... More
An adaptive generalized multiscale discontinuous Galerkin method (GMsDGM) for high-contrast flow problemsSep 11 2014In this paper, we develop an adaptive Generalized Multiscale Discontinuous Galerkin Method (GMs-DGM) for a class of high-contrast flow problems, and derive a-priori and a-posteriori error estimates for the method. Based on the a-posteriori error estimator, ... More
Adaptive mixed GMsFEM for flows in heterogeneous mediaJul 07 2015In this paper, we present two adaptive methods for the basis enrichment of the mixed Generalized Multiscale Finite Element Method (GMsFEM) for solving the flow problem in heterogeneous media. We develop an a-posteriori error indicator which depends on ... More
Coupling of multiscale and multi-continuum approachesFeb 23 2017Simulating complex processes in fractured media requires some type of model reduction. Well-known approaches include multi-continuum techniques, which have been commonly used in approximating subgrid effects for flow and transport in fractured media. ... More
Online basis construction for goal-oriented adaptivity in the Generalized Multiscale Finite Element MethodDec 06 2018In this research, we develop an online enrichment framework for goal-oriented adaptivity within the generalized multiscale finite element method for flow problems in heterogeneous media. The method for approximating the quantity of interest involves construction ... More
Constraint Energy Minimizing Generalized Multiscale Finite Element MethodApr 11 2017The main goal of this paper is to design multiscale basis functions within GMsFEM framework such that the convergence of method is independent of the contrast and linearly decreases with respect to mesh size if oversampling size is appropriately chosen. ... More
Multiscale stabilization for convection diffusion equations with heterogeneous velocity and diffusion coefficientsJul 30 2018We present a new stabilization technique for multiscale convection diffusion problems. Stabilization for these problems has been a challenging task, especially for the case with high Peclet numbers. Our method is based on a constraint energy minimization ... More
A ray-based IPDG method for high-frequency time-domain acoustic wave propagation in inhomogeneous mediaApr 23 2017The numerical approximation of high-frequency wave propagation in inhomogeneous media is a challenging problem. In particular, computing high-frequency solutions by direct simulations requires several points per wavelength for stability and usually requires ... More
Numerical inversion of 3D geodesic X-ray transform arising from traveltime tomographyApr 26 2018In this paper, we consider the inverse problem of determining an unknown function defined in three space dimensions from its geodesic X-ray transform. The standard X-ray transform is defined on the Euclidean metric and is given by the integration of a ... More
Cluster-based Generalized Multiscale Finite Element Method for elliptic PDEs with random coefficientsNov 06 2017We propose a generalized multiscale finite element method (GMsFEM) based on clustering algorithm to study the elliptic PDEs with random coefficients in the multi-query setting. Our method consists of offline and online stages. In the offline stage, we ... More
Generalized multiscale finite element methods for wave propagation in heterogeneous mediaJun 29 2013Numerical modeling of wave propagation in heterogeneous media is important in many applications. Due to the complex nature, direct numerical simulations on the fine grid are prohibitively expensive. It is therefore important to develop efficient and accurate ... More
A three-level multi-continua upscaling method for flow problems in fractured porous mediaOct 03 2018Traditional two level upscaling techniques suffer from a high offline cost when the coarse grid size is much larger than the fine grid size. Thus, multilevel methods are desirable for problems with complex heterogeneities and high contrast. In this paper, ... More
Nonlocal multicontinuum (NLMC) upscaling of mixed dimensional coupled flow problem for embedded and discrete fracture modelsMay 23 2018In this work, we present an upscaled model for mixed dimensional coupled flow problem in fractured porous media. We consider both embedded and discrete fracture models (EFM and DFM) as fine scale models which contain coupled system of equations. For fine ... More
Residual-driven online Generalized Multiscale Finite Element MethodsJan 19 2015The construction of local reduced-order models via multiscale basis functions has been an area of active research. In this paper, we propose online multiscale basis functions which are constructed using the offline space and the current residual. Online ... More
Generalized multiscale finite element methods for space-time heterogeneous parabolic equationsMay 24 2016In this paper, we consider local multiscale model reduction for problems with multiple scales in space and time. We developed our approaches within the framework of the Generalized Multiscale Finite Element Method (GMsFEM) using space-time coarse cells. ... More
Goal-oriented adaptivity for GMsFEMSep 18 2015In this paper we develop two goal-oriented adaptive strategies for a posteriori error estimation within the generalized multiscale finite element framework. In this methodology, one seeks to determine the number of multiscale basis functions adaptively ... More
Online basis construction for goal-oriented adaptivity in the Generalized Multiscale Finite Element MethodDec 06 2018Mar 18 2019In this research, we develop an online enrichment framework for goal-oriented adaptivity within the generalized multiscale finite element method for flow problems in heterogeneous media. The method for approximating the quantity of interest involves construction ... More
Parametric FEM for Shape Optimization applied to Golgi StackFeb 02 2019The thesis is about an application of the shape optimization to the morphological evolution of Golgi stack. Golgi stack consists of multiple layers of cisternae. It is an organelle in the biological cells. Inspired by the Helfrich Model \cite{Helfrich}, ... More
A local-global multiscale mortar mixed finite element method for multiphase transport in heterogeneous mediaMar 25 2019In this paper, we propose a local-global multiscale mortar mixed finite element method (MMMFEM) for multiphase transport in heterogeneous media. We consider the two-phase flow system, the pressure equation is solved via the multiscale mortar mixed finite ... More
Nonlinear nonlocal multicontinua upscaling framework and its applicationsSep 28 2018In this paper, we discuss multiscale methods for nonlinear problems. The main idea of these approaches is to use local constraints and solve problems in oversampled regions for constructing macroscopic equations. These techniques are intended for problems ... More
Reduced-order Deep Learning for Flow DynamicsJan 29 2019Jan 30 2019In this paper, we investigate neural networks applied to multiscale simulations and discuss a design of a novel deep neural network model reduction approach for multiscale problems. Due to the multiscale nature of the medium, the fine-grid resolution ... More
Upscaling method for problems in perforated domains with non-homogeneous boundary conditions on perforations using Non-Local Multi-Continuum method (NLMC)May 23 2018In this paper, we present an upscaling method for problems in perforated domains with non-homogeneous boundary conditions on perforations. Our methodology is based on the recently developed Non-local multicontinuum method (NLMC). The main ingredient of ... More
Online Adaptive Local Multiscale Model Reduction for Heterogeneous Problems in Perforated DomainsMay 24 2016In this paper, we develop and analyze an adaptive multiscale approach for heterogeneous problems in perforated domains. In many applications, these problems have a multiscale nature arising because of the perforations, their geometries, the sizes of the ... More
Constraint Energy Minimizing Generalized Multiscale Finite Element Method for dual continuum modelJul 28 2018The dual continuum model serves as a powerful tool in the modeling of subsurface applications. It allows a systematic coupling of various components of the solutions. The system is of multiscale nature as it involves high heterogeneous and high contrast ... More
Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic mediaSep 11 2014Apr 18 2015It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference ... More
Computational Multiscale Methods for Linear Poroelasticity with High ContrastDec 10 2018In this work, we employ the Constraint Energy Minimizing Generalized Multiscale Finite Element Method (CEM-GMsFEM) to solve the problem of linear heterogeneous poroelasticity with coefficients of high contrast. The proposed method makes use of the idea ... More
GraSPy: Graph Statistics in PythonMar 29 2019We introduce GraSPy, a Python library devoted to statistical inference, machine learning, and visualization of random graphs and graph populations. This package provides flexible and easy-to-use algorithms for analyzing and understanding graphs with a ... More
Non-local Multi-continua Upscaling for Flows in Heterogeneous Fractured MediaAug 28 2017In this paper, we propose a rigorous and accurate non-local (in the oversampled region) upscaling framework based on some recently developed multiscale methods [10]. Our proposed method consists of identifying multi-continua parameters via local basis ... More
Generalized Multiscale Inversion for Heterogeneous ProblemsJul 24 2017In this work, we propose a generalized multiscale inversion algorithm for heterogeneous problems that aims at solving an inverse problem on a computational coarse grid. Previous inversion techniques for multiscale problems seek a coarse-grid media properties, ... More
Multiscale stabilization for convection-dominated diffusion in heterogeneous mediaSep 23 2015We develop a Petrov-Galerkin stabilization method for multiscale convection-diffusion transport systems. Existing stabilization techniques add a limited number of degrees of freedom in the form of bubble functions or a modified diffusion, which may not ... More
Nonlocal multicontinua upscaling for multicontinua flow problems in fractured porous mediaJul 16 2018Our goal of this paper is to develop a new upscaling method for multicontinua flow problems in fractured porous media. We consider a system of equations that describes flow phenomena with multiple flow variables defined on both matrix and fractures. To ... More
Deep Global Model Reduction LearningJul 24 2018In this paper, we combine deep learning concepts and some proper orthogonal decomposition (POD) model reduction methods for predicting flow in heterogeneous porous media. Nonlinear flow dynamics is studied, where the dynamics is regarded as a multi-layer ... More
Generalized Multiscale Multicontinuum Model for Fractured Vuggy Carbonate ReservoirsOct 29 2018Simulating flow in a highly heterogeneous reservoir with multiscale characteristics could be considerably demanding. To tackle this problem, we propose a numerical scheme coupling the Generalized Multiscale Finite Element Method (GMsFEM) with a triple-continuum ... More
Prediction of Discretization of GMsFEM using Deep LearningOct 29 2018In this paper, we propose a deep-learning-based approach to a class of multiscale problems. THe Generalized Multiscale Finite Element Method (GMsFEM) has been proven successful as a model reduction technique of flow problems in heterogeneous and high-contrast ... More
A partial inventory of observational anisotropies in single-dish line-intensity mappingMay 01 2019Line-intensity mapping, being an imperfect observation of the line-intensity field in a cosmological volume, will be subject to various anisotropies introduced in observation. Existing literature in the context of CO and [C II] line-intensity mapping ... More
Staggered discontinuous Galerkin methods for the Helmholtz equations with large wave numberApr 27 2019In this paper we investigate staggered discontinuous Galerkin method for the Helmholtz equation with large wave number on general quadrilateral and polygonal meshes. The method is highly flexible by allowing rough grids such as the trapezoidal grids and ... More
Generalized multiscale finite element method for a strain-limiting nonlinear elasticity modelDec 21 2018In this paper, we consider multiscale methods for nonlinear elasticity. In particular, we investigate the Generalized Multiscale Finite Element Method (GMsFEM) for a strain-limiting elasticity problem. Being a special case of the naturally implicit constitutive ... More
Stabilization of ultra-short pulses in cubic nonlinear mediaDec 13 2005Apr 07 2006We study the propagation of ultra-short pulses in a cubic nonlinear medium. Using multiple-scale technique, we derive a new wave equation that preserves the nonlocal dispersion present in Maxwell's equations. As a result, we are able to understand how ... More
A two-level overlapping Schwarz method with energy-minimizing multiscale coarse basis functionsJan 01 2019A two-level overlapping Schwarz method is developed for second order elliptic problems with highly oscillatory and high contrast coefficients, for which it is known that the standard coarse problem fails to give a robust preconditioner. In this paper, ... More
Edge Multiscale Methods for elliptic problems with heterogeneous coefficientsOct 24 2018In this paper, we proposed two new types of edge multiscale methods motivated by \cite{GL18} to solve Partial Differential Equations (PDEs) with high-contrast heterogeneous coefficients: Edge spectral multiscale Finte Element method (ESMsFEM) and Wavelet-based ... More
BDDC and FETI-DP algorithms with adaptive coarse spaces for three-dimensional elliptic problems with oscillatory and high contrast coefficientsJun 24 2016BDDC and FETI-DP algorithms are developed for three-dimensional elliptic problems with adaptively enriched coarse components. It is known that these enriched components are necessary in the development of robust preconditioners. To form the adaptive coarse ... More
A Constraint energy minimizing generalized multiscale finite element method for parabolic equationsJun 13 2018In this paper, we present a Constraint Energy Minimizing Generalized Multiscale Finite Element Method (CEM-GMsFEM) for parabolic equations with multiscale coefficients, arising from applications in porous media. We will present the construction of CEM-GMsFEM ... More
Adaptive multiscale model reduction with Generalized Multiscale Finite Element MethodsApr 28 2016In this paper, we discuss a general multiscale model reduction framework based on multiscale finite element methods. We give a brief overview of related multiscale methods. Due to page limitations, the overview focuses on a few related methods and is ... More
Constraint Energy Minimizing Generalized Multiscale Finite Element Method in the Mixed FormulationMay 16 2017This paper presents a novel mass-conservative mixed multiscale method for solving flow equations in heterogeneous porous media. The media properties (the permeability) contain multiple scales and high contrast. The proposed method solves the flow equation ... More
Alternative subtraction scheme using Nagy Soper dipolesJan 15 2010We present an alternative subtraction scheme for the treatment of infrared divergences in NLO QCD calculations. In this scheme, the number of transformations is greatly reduced with respect to the standard subtraction scheme by Catani and Seymour. We ... More
Nonlinear Color-Metallicity Relations of Globular Clusters. III. On the Discrepancy in Metallicity between Globular Cluster Systems and their Parent Elliptical GalaxiesSep 23 2011One of the conundrums in extragalactic astronomy is the discrepancy in observed metallicity distribution functions (MDFs) between the two prime stellar components of early-type galaxies-globular clusters (GCs) and halo field stars. This is generally taken ... More
Staggered Discontinuous Galerkin approximation for Immersed Boundary MethodSep 05 2016In this paper, we present a staggered discontinuous Galerkin immersed boundary method (SDG-IBM) for the numerical approximation of fluid-structure interaction. The immersed boundary method is used to model the fluid-structure interaction, while the fluid ... More
Sparse Generalized Multiscale Finite Element Methods and their applicationsJun 29 2015Aug 03 2015In a number of previous papers, local (coarse grid) multiscale model reduction techniques are developed using a Generalized Multiscale Finite Element Method. In these approaches, multiscale basis functions are constructed using local snapshot spaces, ... More
Method and Advantages of Genetic Algorithms in Parameterization of Interatomic Potentials: Metal-OxidesJun 05 2013The method and the advantages of an evolutionary computing based approach using a steady state genetic algorithm (GA) for the parameterization of interatomic potentials for metal oxides within the shell model framework are developed and described. We ... More
Anomalous thermoelectric transport in two-dimensional Bose gasJun 17 2013In condensed matter physics, transport measurements are essential not only for the characterization of materials, but also to discern between quantum phases and identify new ones. The extension of these measurements into atomic quantum gases is emerging ... More
On overlapping domain decomposition methods for high-contrast multiscale problemsMay 25 2017We review some important ideas in the design and analysis of robust overlapping domain decomposition algorithms for high-contrast multiscale problems and propose a domain decomposition method better performance in terms of the number of iterations. The ... More
Generalized multiscale finite element method for the steady state linear Boltzmann equationApr 15 2019The Boltzmann equation, as a model equation in statistical mechanics, is used to describe the statistical behavior of a large number of particles driven by the same physics laws. Depending on the media and the particles to be modeled, the equation has ... More
Assessing the Habitability of the TRAPPIST-1 System Using a 3D Climate ModelMar 16 2017Mar 31 2018The TRAPPIST-1 system provides an extraordinary opportunity to study multiple terrestrial extrasolar planets and their atmospheres. Here we use the National Center for Atmospheric Research Community Atmosphere Model version 4 to study the possible climate ... More
A Kronecker-type identity and the representations of a number as a sum of three squaresFeb 06 2017Feb 13 2017By considering a limiting case of a Kronecker-type identity, we obtain an identity found by both Andrews and Crandall. We then use the Andrews-Crandall identity to give a new proof of a formula of Gauss for the representations of a number as a sum of ... More
An Equivariant Liapunov Stability Test and the Energy-Momentum-Casimir MethodJul 12 2001Feb 11 2002We present an equivariant Liapunov stability criterion for dynamical systems with symmetry. This result yields a simple proof of the energy-momentum-Casimir stability analysis of relative equilibria of equivariant Hamiltonian systems.
On the tenth-order mock theta functionsSep 16 2016Oct 09 2016Using properties of Appell-Lerch functions, we give insightful proofs for six of Ramanujan's identities for the tenth-order mock theta functions.
A double-sum Kronecker-type identityJan 08 2016Aug 11 2016We prove a double-sum analog of an identity known to Kronecker and then express it in terms of functions studied by Appell and Kronecker's student Lerch, in so doing we show that the double-sum analog is of mixed mock modular form. We also give related ... More
Thermal rectification properties of multiple-quantum-dot junctionsJan 08 2010It is illustrated that semiconductor quantum dots (QDs) embedded into an insulating matrix connected with metallic electrodes and some vacuum space can lead to significant thermal rectification effect. A multilevel Anderson model is used to investigate ... More
Light emitting single electron transistorsJun 03 2006Jun 22 2006The dynamic properties of light-emitting single-electron transistors (LESETs) made from quantum dots are theoretically studied by using nonequilibrium Green's function method. Holes residing at QD created by small ac signals added in the base electrode ... More
Stark effect on the exciton complexes of individual quantum dotsOct 17 2005The emission spectrum of exciton complexes formed in individual self-assembled quantum dots (QDs) embedded into a p-n junction is theoretically studied using an effective mass model. We calculate the particle Coulomb interactions, eletron-hole overlaps ... More
Tunneling current spectroscopy of a nanostructure junction involving multiple energy levelsFeb 05 2007A multi-level Anderson model is employed to simulate the system of a nanostructure tunnel junction with any number of one-particle energy levels. The tunneling current, including both shell-tunneling and shell-filling cases, is theoretically investigated ... More
Superlattice nanowire heat engines with direction-dependent power output and heat currentApr 15 2019Heat engines (HEs) made of low dimensional structures offer promising applications in energy harvesting due to their reduced phonon thermal conductance. Many efforts have been devoted to the design of HEs made of quantum-dot (QD) superlattice nanowire ... More
Thermoelectric Properties of a Semiconductor Quantum Dot Chain Connected to Metallic ElectrodesSep 04 2012Jan 10 2013The thermoelectric properties of a semiconduct quantum dot chain (SQDC) connected to metallic electrodes are theoretically investigated in the Coulomb blockade regime. An extended Hubbard model is employed to simulate the SQDC system consisted of {\color{blue}N=2,3,4, ... More
Bistable states of quantum dot array junctions for high-density memoryDec 29 2008We demonstrate that two-dimensional (2D) arrays of coupled quantum dots (QDs) with six-fold degenerate p orbitals can display bistable states, suitable for application in high-density memory device with low power consumption. Due to the inter-dot coupling ... More
Stokes tomography of radio pulsar magnetospheres. II. Millisecond pulsarsApr 06 2011The radio polarization characteristics of millisecond pulsars (MSPs) differ significantly from those of non-recycled pulsars. In particular, the position angle (PA) swings of many MSPs deviate from the S-shape predicted by the rotating vector model, even ... More
Stokes tomography of radio pulsar magnetospheres. I. Linear polarizationOct 14 2010Dec 20 2010Polarimetric studies of pulsar radio emission traditionally concentrate on how the Stokes vector (I, Q, U, V) varies with pulse longitude, with special emphasis on the position angle (PA) swing of the linearly polarized component. The interpretation of ... More
Effects of electron correlation on the photocurrent in quantum dot infrared photodetectorsOct 16 2002The effect of electron correlation on the photocurrent of self-assembled InAs/InGaAs quantum dot infrared photo-detector (QDIPs) is studied. It is found that Coulomb interaction and level mixing in the many-body open system lead to double peaks associated ... More
Long distance coherent tunneling effect on the charge and heat currents in serially coupled triple quantum dotsSep 06 2013Mar 12 2014The effect of long distance coherent tunneling (LDCT) on the charge and heat currents in serially coupled triple quantum dots (TQDs) connected to electrodes is illustrated by using a combination of the extended Hurbbard model and Anderson model. The charge ... More
Bipolar thermoelectric effect in a srially coupled quantum dot systemApr 14 2011Nov 01 2011The Seebeck coefficient (S) of a serially coupled quantum dot (SCQD) junction system is theoretically studied via a two-level Anderson model. A change of sign in S with respect to temperature is found, which arises from the competition between tunneling ... More
Thermoelectric and thermal rectification properties of quantum dot junctionsFeb 21 2010The electrical conductance, thermal conductance, thermal power and figure of merit (ZT) of semiconductor quantum dots (QDs) embedded into an insulator matrix connected with metallic electrodes are theoretically investigated in the Coulomb blockade regime. ... More
Tunnelling current and emission spectrum of a single electron transistor under optical pumpingJun 01 2005Theoretical studies of the tunnelling current and emission spectrum of a single electron transistor (SET) under optical pumping are presented. The calculation is performed via Keldysh Green's function method within the Anderson model with two energy levels. ... More
Untangling the Web of E-Research: Towards a Sociology of Online KnowledgeAug 14 2009e-Research is a rapidly growing research area, both in terms of publications and in terms of funding. In this article we argue that it is necessary to reconceptualize the ways in which we seek to measure and understand e-Research by developing a sociology ... More
Restricted testing for positive operatorsSep 13 2018We answer a question of T. Hyt\"onen, regarding the restriction of testing conditions to doubling cubes, in the affirmative for fractional integrals and the maximal function, although for the maximal function we only obtain a restriction to parentally ... More
A Simple Holographic InsulatorJun 16 2014Jul 11 2014We present a simple holographic model of an insulator. Unlike most previous holographic insulators, the zero temperature infrared geometry is completely nonsingular. Both the low temperature DC conductivity and the optical conductivity at zero temperature ... More
Comment on "Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD" [Phys. Lett. B 763, 52--59 (2016)]Jan 27 2017Mar 22 2017In the cross section for single-inclusive jet production in electron-nucleon collisions, the distribution of a quark in an electron appears at next-to-next-to-leading order. The numerical calculations in Ref. [1] were carried out using a perturbative ... More
Restricted testing for the Hardy-Littlewood maximal functionNov 27 2018We answer a special case of a question of T. Hytonen regarding the two weight norm inequality for the maximal function M in the affirmative, namely that there is a constant D > 1, depending only on dimension n, such that the two weight norm inequality ... More
Indirect Inference With(Out) ConstraintsJul 21 2016Aug 30 2016The traditional implementation of Indirect Inference (I-I) is to perform inference on structural parameters $\theta$ by matching observed and simulated auxiliary statistics. These auxiliary statistics are consistent estimators of instrumental parameters ... More
DiscoverFriends: Secure Social Network Communication in Mobile Ad Hoc NetworksMay 27 2015May 02 2016This paper presents a secure communication application called DiscoverFriends. Its purpose is to securely communicate to a group of online friends while bypassing their respective social networking servers under a mobile ad hoc network environment. DiscoverFriends ... More
Non-Asymptotic Classical Data Compression with Quantum Side InformationMar 20 2018Mar 26 2018In this paper, we analyze classical data compression with quantum side information (also known as the classical-quantum Slepian-Wolf protocol) in the so-called large and moderate deviation regimes. In the non-asymptotic setting, the protocol involves ... More
Computational multiscale methods for linear heterogeneous poroelasticityJan 02 2018Dec 22 2018We consider a strongly heterogeneous medium saturated by an incompressible viscous fluid as it appears in geomechanical modeling. This poroelasticity problem suffers from rapidly oscillating material parameters, which calls for a thorough numerical treatment. ... More