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Results for "Xu Liu"

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Budget-aware Online Task Assignment in Spatial CrowdsourcingJul 26 2018The prevalence of mobile internet techniques stimulates the emergence of various spatial crowdsourcing applications. Certain of the applications serve for requesters, budget providers, who submit a batch of tasks and a fixed budget to platform with the ... More
Elastomeric 2D Grating and Hemispherical Optofluidic Chamber for Multifunctional Fluidic SensingFeb 07 2014We present an optofluidic sensor based on an elastomeric two-dimensional (2D) grating integrated inside a hemispherical fluid chamber. Laser beam is diffracted before (reflection) and after (transmission) going through the grating and liquid in the dome ... More
Function Based Nonlinear Least Squares and Application to Jelinski--Moranda Software Reliability ModelAug 25 2011A function based nonlinear least squares estimation (FNLSE) method is proposed and investigated in parameter estimation of Jelinski-Moranda software reliability model. FNLSE extends the potential fitting functions of traditional least squares estimation ... More
A Unified Gas Kinetic Scheme for Multi-scale Plasma TransportSep 17 2016A unified gas kinetic scheme (UGKS) for multi-scale and multi-component plasma transport is constructed. The current scheme is a direct modeling method, where the time evolution solutions from the Vlasov-BGK equations for both electron and ion, and the ... More
Very strong approximation for certain algebraic varietiesMay 08 2014Sep 18 2014Let F be a global field. In this work, we show that the Brauer-Manin condition on adelic points for subvarieties of a torus T over F cuts out exactly the rational points, if either F is a function field or, if F is the field of rational numbers and T ... More
A Monte Carlo Study on the Identification of Quark-gluon Fusion Product in QCD-instanton Induced Processes in Deep-inelastic ScatteringOct 18 2006Different methods to reconstruct the quark-gluon fusion product and current jet are tried in deep-inelastic e-p scattering events with instanton as background generated by QCDINS Monte Carlo code. A comparison of these methods are performed and a good ... More
A proof of the Faber intersection number conjectureMar 14 2008Dec 03 2009We prove the famous Faber intersection number conjecture and other more general results by using a recursion formula of $n$-point functions for intersection numbers on moduli spaces of curves. We also present some vanishing properties of Gromov-Witten ... More
An effective recursion formula for computing intersection numbersOct 29 2007We prove a new effective recursion formula for computing all intersection indices (integrals of $\psi$ classes) on the moduli space of curves, inducting only on the genus.
A weighted identity for stochastic partial differential operators and its applicationsAug 20 2015In this paper, a pointwise weighted identity for some stochastic partial differential operators (with complex principal parts) is established. This identity presents a unified approach in studying the controllability, observability and inverse problems ... More
The countable versus uncountable branching recurrences in computability logicJul 19 2011This paper introduces a new simplified version of the countable branching recurrence of Computability Logic, proves its equivalence to the old one, and shows that the basic logic induced by it is a proper superset of the basic logic induced by the uncountable ... More
Einstein frame and Jordan frame revisited: are they mathematically equivalent?Jun 27 2011Jul 07 2011This paper has been withdrawn by the author due to a crucial sign error in equation (5).
The parallel versus branching recurrences in computability logicJul 12 2011This paper shows that the basic logic induced by the parallel recurrence of Computability Logic is a proper superset of the basic logic induced by the branching recurrence. The latter is known to be precisely captured by the cirquent calculus system CL15, ... More
K-stability of cubic threefoldsJun 06 2017Jan 26 2019We prove the K-moduli space of cubic threefolds is identical to their GIT moduli. More precisely, the K-(semi,poly)-stability of cubic threefolds coincide to the corresponding GIT stabilities, which could be explicitly calculated. In particular, this ... More
Some Asymptotic Results of Gaussian Random Fields with Varying Mean Functions and the Associated ProcessesApr 10 2011Dec 02 2011In this paper, we derive tail approximations of integrals of exponential functions of Gaussian random fields with varying mean functions and approximations of the associated point processes. This study is motivated naturally by multiple applications such ... More
Liquid refractive index sensing independent of opacity using an optofluidic sensor based on diffractionOct 03 2014Oct 15 2014We have implemented a multi-functional optofluidic sensor that can monitor changes in the refractive index and pressure of biofluid simultaneously and can detect free-solution molecular interaction in-situ. In this paper, we demonstrate two major improvements ... More
Monolithic Integrations of Slanted Silicon Nanostructures on 3D Microstructures and Their Application to Surface Enhanced Raman SpectroscopyFeb 07 2014We demonstrated fabrication of black silicon with slanted nanocone array on both planar and 3D micro and meso scale structures produced by a high-throughput lithography-free oblique-angle plasma etching process. Nanocones with gradual change in height ... More
Lithography-free sub-100nm nanocone array antireflection layer for low-cost silicon solar cellFeb 07 2014High density and uniformity sub-100nm surface oxidized silicon nanocone forest structure is created and integrated onto the existing texturization microstructures on photovoltaic device surface by a one-step high throughput plasma enhanced texturization ... More
Quick Detection of Contaminants Leaching from Polypropylene Centrifuge Tube with Surface Enhanced Raman Spectroscopy and Ultra Violet Absorption SpectroscopyFeb 07 2014Anomalous surface enhanced Raman scattering (SERS) peaks are identified for liquid sample stored in polypropylene centrifuge tubes (PP tube) for months. We observed the unexpected Raman peaks during experiments for Thiamine Hydrochloride aqueous solution ... More
Accelerating Stochastic Gradient Descent Using Antithetic SamplingOct 07 2018(Mini-batch) Stochastic Gradient Descent is a popular optimization method which has been applied to many machine learning applications. But a rather high variance introduced by the stochastic gradient in each step may slow down the convergence. In this ... More
A Paradigm for Modeling and Computation of Gas DynamicsAug 01 2016In the continuum flow regime, the Navier-Stokes equations are usually used for the description of gas dynamics. On the other hand, the Boltzmann equation is applied for the rarefied gas dynamics. Both equations are constructed from modeling flow physics ... More
A Unified Gas Kinetic Scheme for Multi-scale and Multi-component Plasma TransportSep 17 2016Feb 22 2017A unified gas kinetic scheme (UGKS) for multi-scale and multi-component plasma transport is constructed. The current scheme is a direct modeling method, where the time evolution solutions from the Vlasov-BGK equations of electron and ion and the Maxwell ... More
Finite Codimensional Controllability, and Optimal Control Problems with Endpoint State ConstraintsOct 02 2018In this paper, motivated by the study of optimal control problems for infinite dimensional systems with endpoint state constraints, we introduce the notion of finite codimensional (exact/approximate) controllability. Some equivalent criteria on the finite ... More
Mechanism for linear preferential attachment in growing networksAug 20 2007The network properties of a graph ensemble subject to the constraints imposed by the expected degree sequence are studied. It is found that the linear preferential attachment is a fundamental rule, as it keeps the maximal entropy in sparse growing networks. ... More
Extended phase space thermodynamics for third order Lovelock black holes in diverse dimensionsMay 16 2014May 22 2014Treating the cosmological constant as thermodynamic pressure and its conjugate as thermodynamic volume, we investigate the critical behavior of the third order Lovelock black holes in diverse dimensions. For black hole horizons with different normalized ... More
The Local Structure of Lie BialgebroidsOct 07 2002We study the local structure of Lie bialgebroids at regular points. In particular, we classify all transitive Lie bialgebroids. In special cases, they are connected to classical dynamical $r$-matrices and matched pairs induced by Poisson group actions ... More
A Robust Alternating Direction Method for Constrained Hybrid Variational Deblurring ModelAug 31 2013Oct 02 2013In this work, a new constrained hybrid variational deblurring model is developed by combining the non-convex first- and second-order total variation regularizers. Moreover, a box constraint is imposed on the proposed model to guarantee high deblurring ... More
Time series of Internet AS-level topology graphs: four patterns and one modelDec 26 2008Researchers have proposed a variety of Internet topology models. However almost all of them focus on generating one graph based on one single static source graph. On the other hand, Internet topology is evolving over time continuously with the addition ... More
Covert Communication with A Full-Duplex Receiver Based on Channel Distribution InformationOct 12 2018Nov 10 2018In this work, we consider a system of covert communication with the aid of a full-duplex (FD) receiver to enhance the performance in a more realistic scenario, i.e., only the channel distribution information (CDI) rather than channel state information ... More
Constructing Intrinsic Delaunay Triangulations from the Dual of Geodesic Voronoi DiagramsMay 21 2015Intrinsic Delaunay triangulation (IDT) is a fundamental data structure in computational geometry and computer graphics. However, except for some theoretical results, such as existence and uniqueness, little progress has been made towards computing IDT ... More
Local Rademacher Complexity for Multi-label LearningOct 26 2014We analyze the local Rademacher complexity of empirical risk minimization (ERM)-based multi-label learning algorithms, and in doing so propose a new algorithm for multi-label learning. Rather than using the trace norm to regularize the multi-label predictor, ... More
Accelerating Universe in a Big Bounce ModelApr 24 2003Dec 05 2003Recent observations of Type Ia supernovae provide evidence for the acceleration of our universe, which leads to the possibility that the universe is entering an inflationary epoch. We simulate it under a ``big bounce'' model, which contains a time variable ... More
Dependency length minimization: Puzzles and PromisesSep 15 2015In the recent issue of PNAS, Futrell et al. claims that their study of 37 languages gives the first large scale cross-language evidence for Dependency Length Minimization, which is an overstatement that ignores similar previous researches. In addition,this ... More
Symmetry Protected Topological Hopf Insulator and its GeneralizationsDec 15 2016We study a class of $3d$ and $4d$ topological insulators whose topological nature is characterized by the Hopf map and its generalizations. We identify the symmetry $\mathcal{C}^\prime$, a generalized particle-hole symmetry that gives the Hopf insulator ... More
Compressed Sensing with Prior Information via Maximizing CorrelationMay 22 2017Compressed sensing (CS) with prior information concerns the problem of reconstructing a sparse signal with the aid of a similar signal which is known beforehand. We consider a new approach to integrate the prior information into CS via maximizing the ... More
A Guided Tour to Normalized VolumeJun 19 2018Jan 25 2019This is a survey on the recent theory on minimizing the normalized volume function attached to any klt singularities.
Stochastic Variance Reduction for Policy Gradient EstimationOct 17 2017Mar 29 2018Recent advances in policy gradient methods and deep learning have demonstrated their applicability for complex reinforcement learning problems. However, the variance of the performance gradient estimates obtained from the simulation is often excessive, ... More
Evaluating Semantic Rationality of a Sentence: A Sememe-Word-Matching Neural Network based on HowNetSep 11 2018Automatic evaluation of semantic rationality is an important yet challenging task, and current automatic techniques cannot well identify whether a sentence is semantically rational. The methods based on the language model do not measure the sentence by ... More
Deep Adaptive Proposal Network for Object Detection in Optical Remote Sensing ImagesJul 19 2018Object detection is a fundamental and challenging problem in aerial and satellite image analysis. More recently, a two-stage detector Faster R-CNN is proposed and demonstrated to be a promising tool for object detection in optical remote sensing images, ... More
Filament Power Control for Gyrotrons in EAST ECRH SystemAug 29 2018The electron cyclotron heating system including four gyrotrons is under developed in the Institute of Plasma Physics, Chinese Academy of Sciences. The filament is an important part of the gyrotron, which is used to heat the cathode. Each gyrotron has ... More
MHP-VOS: Multiple Hypotheses Propagation for Video Object SegmentationApr 17 2019We address the problem of semi-supervised video object segmentation (VOS), where the masks of objects of interests are given in the first frame of an input video. To deal with challenging cases where objects are occluded or missing, previous work relies ... More
The expression of ensemble average internal energy in long-range interaction complex system and its statistical physical propertiesFeb 01 2019In this paper, we attempt to derive the expression of ensemble average internal energy in long-range interaction complex system. Further, the Shannon entropy hypothesis is used to derive the probability distribution function of energy. It is worth mentioning ... More
Symmetry-assisted protection and compensation of hidden spin polarization in centrosymmetric systemsFeb 27 2019It is recently noted that in certain centrosymmetric compounds, spin-orbit interaction couples each local sector that lacks inversion symmetry and thus leads to visible spin polarization effects in the real space, dubbed as 'hidden spin polarization (HSP)'. ... More
Cell Size Effect on Computational Fluid Dynamics: The Limitation Principle for Flow SimulationJun 26 2017May 25 2018For theoretical gas dynamics, the flow regimes are classified according to the Knudsen number. For computational fluid dynamics (CFD), the numerical flow field is the projection of the physical flow field onto the discrete space and time, which is related ... More
Simplification of the Flux Function for a Higher-order Gas-kinetic Evolution ModelOct 04 2016The higher-order gas-kinetic scheme for solving the Navier-Stokes equations has been studied in recent years. In addition to the use of higher-order reconstruction techniques, many terms are used in the Taylor expansion of the gas distribution functions. ... More
A Weighted Common Subgraph Matching AlgorithmNov 04 2014We propose a weighted common subgraph (WCS) matching algorithm to find the most similar subgraphs in two labeled weighted graphs. WCS matching, as a natural generalization of the equal-sized graph matching or subgraph matching, finds wide applications ... More
Recovery of Structured Signals with Prior Information via Maximizing CorrelationOct 27 2017This paper considers the problem of recovering a structured signal from a relatively small number of noisy measurements with the aid of a similar signal which is known beforehand. We propose a new approach to integrate prior information into the standard ... More
New multiplicative perturbation bounds for the generalized polar decompositionJul 09 2018Some new Frobenius norm bounds of the unique solution to certain structured Sylvester equation are derived. Based on the derived norm upper bounds, new multiplicative perturbation bounds are provided both for subunitary polar factors and positive semi-definite ... More
Zipf's law in 50 languages: its structural pattern, linguistic interpretation, and cognitive motivationJul 05 2018Zipf's law has been found in many human-related fields, including language, where the frequency of a word is persistently found as a power law function of its frequency rank, known as Zipf's law. However, there is much dispute whether it is a universal ... More
The influence of Chunking on Dependency Crossing and DistanceSep 03 2015This paper hypothesizes that chunking plays important role in reducing dependency distance and dependency crossings. Computer simulations, when compared with natural languages,show that chunking reduces mean dependency distance (MDD) of a linear sequence ... More
On the General Ericksen-Leslie System: Parodi's Relation, Well-posedness and StabilityMay 11 2011Oct 03 2012In this paper we investigate the role of Parodi's relation in the well-posedness and stability of the general Ericksen-Leslie system modeling nematic liquid crystal flows. First, we give a formal physical derivation of the Ericksen-Leslie system through ... More
Global Well-posedness of the Two Dimensional Beris-Edwards System with General Laudau-de Gennes Free EnergyOct 23 2018In this paper, we consider the Beris-Edwards system for incompressible nematic liquid crystal flows. The system under investigation consists of the Navier-Stokes equations for the fluid velocity $\mathbf{u}$ coupled with an evolution equation for the ... More
Boundary regularity for the second boundary-value problem of Monge-Ampère equations in dimension twoJun 25 2018In this paper, we introduce an iteration argument to prove that a convex solution to the Monge-Amp\`ere equation $\mbox{det } D^2 u =f $ in dimension two subject to the natural boundary condition $Du(\Omega) = \Omega^*$ is $C^{2,\alpha}$ smooth up to ... More
Signature of non-Markovianity in time-resolved energy transferJan 17 2017Jan 18 2017We explore signatures of the non-Markovianity in the time-resolved energy transfer processes for quantum open systems. Focusing on typical systems such as the exact solvable damped Jaynes-Cummings model and the general spin-boson model, we establish quantitative ... More
Green's functions for spin boson systems: Beyond conventional perturbation theoriesAug 17 2016Unraveling general properties of Green's functions of quantum dissipative systems is of both experimental relevance and theoretical interest. Here, we study the spin-boson model as a prototype. By utilizing the Majorana- Fermion representation together ... More
A reciprocal branching problem for automorphic representations and global Vogan packetsDec 07 2018Let $G$ be a group and $H$ be a subgroup of $G$. The classical branching rule (or symmetry breaking) asks: For an irreducible representation $\pi$ of $G$, determine the occurrence of an irreducible representation $\sigma$ of $H$ in the restriction of ... More
Greedy Criterion in Orthogonal Greedy LearningApr 20 2016Orthogonal greedy learning (OGL) is a stepwise learning scheme that starts with selecting a new atom from a specified dictionary via the steepest gradient descent (SGD) and then builds the estimator through orthogonal projection. In this paper, we find ... More
Polarimetric Convolutional Network for PolSAR Image ClassificationJul 09 2018Apr 03 2019The approaches for analyzing the polarimetric scattering matrix of polarimetric synthetic aperture radar (PolSAR) data have always been the focus of PolSAR image classification. Generally, the polarization coherent matrix and the covariance matrix obtained ... More
Understanding the Characteristics of Internet Short Video Sharing: YouTube as a Case StudyJul 25 2007Established in 2005, YouTube has become the most successful Internet site providing a new generation of short video sharing service. Today, YouTube alone comprises approximately 20% of all HTTP traffic, or nearly 10% of all traffic on the Internet. Understanding ... More
Physical Modeling and Numerical Studies of Three-dimensional Non-equilibrium Multi-temperature FlowsOct 10 2018Oct 11 2018For increasingly rarefied flowfields, the Navier-Stokes (NS) equations lose accuracy partially due to the single temperature approximation. To overcome this barrier, a continuum multi-temperature model based on the Bhatnagar-Gross-Krook (BGK) equation ... More
Exact phase transition of backtrack-free search with implications on the power of greedy algorithmsNov 19 2008Backtracking is a basic strategy to solve constraint satisfaction problems (CSPs). A satisfiable CSP instance is backtrack-free if a solution can be found without encountering any dead-end during a backtracking search, implying that the instance is easy ... More
A Unified Gas-kinetic Scheme for Continuum and Rarefied Flows VI: Dilute Disperse Gas-Particle Multiphase SystemFeb 14 2018Sep 11 2018In this paper, a unified gas kinetic scheme for multiphase dilute gas-particle system is proposed. The UGKS multiphase (UGKS-M) is a finite volume method, which captures flow physics in the regimes from collisionless multispecies transport to the two-fluid ... More
A novel weighting scheme for random $k$-SATOct 16 2013Consider a random $k$-CNF formula $F_{k}(n, rn)$ with $n$ variables and $rn$ clauses. For every truth assignment $\sigma\in \{0, 1\}^{n}$ and every clause $c=\ell_{1}\vee\cdots\vee\ell_{k}$, let $d=d(\sigma, c)$ be the number of satisfied literal occurrences ... More
Internet Resource Pricing Models, Mechanisms, and MethodsApr 11 2011With the fast development of video and voice network applications, CDN (Content Distribution Networks) and P2P (Peer-to-Peer) content distribution technologies have gradually matured. How to effectively use Internet resources thus has attracted more and ... More
Clustering with Transitive Distance and K-Means DualityNov 22 2007Recent spectral clustering methods are a propular and powerful technique for data clustering. These methods need to solve the eigenproblem whose computational complexity is $O(n^3)$, where $n$ is the number of data samples. In this paper, a non-eigenproblem ... More
Q factor in numerical simulations of DPSK with optical delay demodulationApr 01 2003A simple model is used to estimate the Q factor in numerical simulations of differential phase shift keying (DPSK) with optical delay demodulation and balanced detection. It is found that an alternative definition of Q is needed for DPSK in order to have ... More
Initial orientation effect and selecting desired events in 520AMeV/u U-U collisionsNov 19 2008How to select out those collisions with the desired geometry such as tip-tip and/or body-body in experiment is one key point for performing high energy UU collisions. With a relativistic transport model, we performed a simulation for deformed UU collision ... More
Two Particle States in an Asymmetric Box and the Elastic Scattering PhasesApr 01 2004The exact two-particle energy eigenstates in a generic asymmetric rectangular box with periodic boundary conditions in all three directions are studied. Their relation with the elastic scattering phases of the two particles in the continuum are obtained ... More
Two Particle States in a Box and the $s$-Matrix in Multi-Channel ScatteringAug 25 2005Aug 29 2005Using a quantum mechanical model, the exact energy eigenstates for two-particle two-channel scattering are studied in a cubic box with periodic boundary conditions. A relation between the exact energy eigenvalue in the box and the two-channel $S$-matrix ... More
Massive Domain Wall Fermions on Four-dimensional Anisotropic LatticesJul 17 2006Jul 27 2006We formulate the massive domain wall fermions on anisotropic lattices. For the massive domain wall fermion, we find that the dispersion relation assumes the usual form in the low momentum region when the bare parameters are properly tuned. The quark self-energy ... More
A Large Family of Multi-path Dual Congestion Control AlgorithmsApr 19 2011The goal of traffic management is efficiently utilizing network resources via adapting of source sending rates and routes selection. Traditionally, this problem is formulated into a utilization maximization problem. The single-path routing scheme fails ... More
Depletion induced like-charge attraction: Understanding from a self-consistent field model with dielectric effectJul 17 2015Mar 19 2016Electrostatic correlation and dielectric effects are of significant importance in ionic structure properties near charged surfaces. These effects can be modeled by a system of self-consistent field equations with the approximate potential of mean force ... More
On a Modified DeGroot-Friedkin Model of Opinion DynamicsMar 13 2015Feb 29 2016This paper studies the opinion dynamics that result when individuals consecutively discuss a sequence of issues. Specifically, we study how individuals' self-confidence levels evolve via a reflected appraisal mechanism. Motivated by the DeGroot-Friedkin ... More
Skew $N$-Derivations on Semiprime RingsJun 15 2012For a ring $R$ with an automorphism $\sigma$, an $n$-additive mapping $\Delta:R\times R\times... \times R \rightarrow R$ is called a skew $n$-derivation with respect to $\sigma$ if it is always a $\sigma$-derivation of $R$ for each argument. Namely, it ... More
On the Equivalence of Semidifinite Relaxations for MIMO Detection with General ConstellationsFeb 18 2019The multiple-input multiple-output (MIMO) detection problem is a fundamental problem in modern digital communications. Semidefinite relaxation (SDR) based algorithms are a popular class of approaches to solving the problem because the algorithms have ... More
A topological interpretation about $m_{G, N}$ for finite group $G$ with normal subgroup $N$Mar 05 2018Let $G$ be a finite group and $N\unlhd G$. In this note, we construct a class poset of $G$ for some cyclic subgroup $C$ of $G$. And we find a relation between $m_{G,N}$ and the Euler characteristic of some nerve spaces of these posets(see Main Theorem). ... More
Kelvin Helmholtz instability in an ultrathin air film causes drop splashing on smooth surfacesSep 03 2015When a fast-moving drop impacts onto a smooth substrate, splashing will be produced at the edge of the expanding liquid sheet. This ubiquitous phenomenon lacks a fundamental understanding. Combining experiment with model, we illustrate that the ultrathin ... More
Unseen Class Discovery in Open-world ClassificationJan 17 2018This paper concerns open-world classification, where the classifier not only needs to classify test examples into seen classes that have appeared in training but also reject examples from unseen or novel classes that have not appeared in training. Specifically, ... More
Deforming submanifolds of arbitrary codimension in a sphereMar 31 2012In this paper, we prove some convergence theorems for the mean curvature flow of closed submanifolds in the unit sphere $\mathbb{S}^{n+d}$ under integral curvature conditions. As a consequence, we obtain several differentiable sphere theorems for certain ... More
Removing out-of-focus blur from a single imageAug 28 2018Reproducing an all-in-focus image from an image with defocus regions is of practical value in many applications, eg, digital photography, and robotics. Using the output of some existing defocus map estimator, existing approaches first segment a de-focused ... More
Rationalization and Identification of Binary Games with Correlated TypesOct 27 2016This paper studies the rationalization and identification of binary games where players have correlated private types. Allowing for correlation is crucial in global games and in models with social interactions as it represents correlated information and ... More
Theory of self-learning $Q$-matrixOct 29 2010Dec 10 2013Cognitive assessment is a growing area in psychological and educational measurement, where tests are given to assess mastery/deficiency of attributes or skills. A key issue is the correct identification of attributes associated with items in a test. In ... More
Acceleration of Primal-Dual Methods by Preconditioning and Simple Subproblem ProceduresNov 21 2018Jan 08 2019Primal-Dual Hybrid Gradient (PDHG) and Alternating Direction Method of Multipliers (ADMM) are two widely-used first-order optimization methods. They reduce a difficult problem to simple subproblems, so they are easy to implement and have many applications. ... More
Self-energy-modified Poisson-Nernst-Planck equations: WKB approximation and finite-difference approachesApr 01 2014Jul 19 2014We propose a modified Poisson-Nernst-Planck (PNP) model to investigate charge transport in electrolytes of inhomogeneous dielectric environment. The model includes the ionic polarization due to the dielectric inhomogeneity and the ion-ion correlation. ... More
The Pontryagin Class for Pre-Courant AlgebroidsMay 26 2012Mar 19 2016In this paper, we show that the Jacobiator $J$ of a pre-Courant algebroid is closed naturally. The corresponding equivalence class $[J^\flat]$ is defined as the Pontryagin class, which is the obstruction of a pre-Courant algebroid to be deformed into ... More
Global regularity of optimal mappings in non-convex domainsJan 29 2019In this paper, we establish a global regularity result for the optimal transport problem with the quadratic cost, where the domains may not be convex. This result is obtained by a perturbation argument, using a recent global regularity of optimal transportation ... More
Reachable Space Characterization of Markov Decision Processes with Time VariabilityMay 22 2019May 25 2019We propose a solution to a time-varying variant of Markov Decision Processes which can be used to address decision-theoretic planning problems for autonomous systems operating in unstructured outdoor environments. We explore the time variability property ... More
Controlled CNN-based Sequence Labeling for Aspect ExtractionMay 15 2019May 29 2019One key task of fine-grained sentiment analysis on reviews is to extract aspects or features that users have expressed opinions on. This paper focuses on supervised aspect extraction using a modified CNN called controlled CNN (Ctrl). The modified CNN ... More
Five-dimensional vacuum Einstein spacetimes in C-metric like coordinatesMay 14 2010Sep 28 2010A 5-dimensional Einstein spacetime with (non)vanishing cosmological constant is analyzed in detail. The metric is in close analogy with the 4-dimensional massless uncharged C-metric in many aspects. The coordinate system, horizons and causal structures, ... More
Projected Wirtinger Gradient Descent for Low-Rank Hankel Matrix Completion in Spectral Compressed SensingJul 14 2015This paper considers reconstructing a spectrally sparse signal from a small number of randomly observed time-domain samples. The signal of interest is a linear combination of complex sinusoids at $R$ distinct frequencies. The frequencies can assume any ... More
Wyner's Common Information: Generalizations and A New Lossy Source Coding InterpretationJan 10 2013Wyner's common information was originally defined for a pair of dependent discrete random variables. Its significance is largely reflected in, hence also confined to, several existing interpretations in various source coding problems. This paper attempts ... More
Extremely Metal-Poor Star Candidates in the SDSSNov 06 2012For a sample of metal-poor stars (-3.3< [Fe/H] <-2.2) that have high-resolution spectroscopic abundance determinations, we have measured equivalent widths (EW) of the Ca II K, Mg I b and near-infrared (NIR) Ca II triplet lines using low-resolution spectra ... More
Dirac structures and Poisson homogeneous spacesNov 08 1996Poisson homogeneous spaces for Poisson groupoids are classfied in terms of Dirac structures for the corresponding Lie bialgebroids. Applications include Drinfel'd's classification in the case of Poisson groups and a description of leaf spaces of foliations ... More
Adaptive Mesh Representation and Restoration of Biomedical ImagesJun 27 2014The triangulation of images has become an active research area in recent years for its compressive representation and ease of image processing and visualization. However, little work has been done on how to faithfully recover image intensities from a ... More
A Symplecticity-preserving Gas-kinetic Scheme for Hydrodynamic Equations under Gravitational FieldDec 15 2010A well-balanced scheme for a gravitational hydrodynamic system is defined as a scheme which could precisely preserve a hydrostatic isothermal solution. In this paper, we will construct a well-balanced gas-kinetic symplecticity-preserving BGK (SP-BGK) ... More
Unified Gas-kinetic Wave-Particle methods I: Continuum and Rarefied Gas FlowNov 17 2018The unified gas-kinetic scheme (UGKS) provides a framework for simulating multiscale transport with the updates of both gas distribution function and macroscopic flow variables on the cell size and time step scales. The multiscale dynamics in UGKS is ... More
An Alternative Analysis of Discontinuous Galerkin Method for Hyperbolic Conservation LawJan 16 2016Jan 19 2016The development and application of the Discontinuous Galerkin (DG) method have attracted great attention in computational fluid dynamics (CFD) com- munity in the past decades. The underlying reason for such an intensive investigation is due to favorable ... More
Complex networks: A mixture of power-law and Weibull distributionsAug 05 2009Sep 01 2009Complex networks have recently aroused a lot of interest. However, network edges are considered to be the same in almost all these studies. In this paper, we present a simple classification method, which divides the edges of undirected, unweighted networks ... More
Extremal graphs for vertex-degree-based invariants with given degree sequencesSep 06 2018For a symmetric bivariable function $f(x,y)$, let the {\it connectivity function} of a connected graph $G$ be $M_f(G)=\sum_{uv\in E(G)}f(d(u),d(v))$, where $d(u)$ is the degree of vertex $u$. In this paper, we prove that for an escalating (de-escalating) ... More
Energetically stable discretizations for charge carrier transport and electrokinetic modelsMar 15 2015A finite element discretization using a method of lines approached is proposed for approximately solving the Poisson-Nernst-Planck (PNP) equations. This discretization scheme enforces positivity of the computed solutions, corresponding to particle density ... More
Modified Poisson-Nernst-Planck model with accurate Coulomb correlation in variable mediaNov 20 2016Aug 21 2017We derive a set of modified Poisson-Nernst-Planck (mPNP) equations for ion transport from the variation of the free energy functional which includes the many-body Coulomb correlation in media of variable dielectric coefficient. The correlation effects ... More