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Results for "Sun-Ju Chung"

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Properties of Microlensing Central Perturbations by Planets in Binary Stellar Systems under the Strong Finite-Source EffectMar 05 2010Mar 25 2010We investigate high-magnification events caused by planets in wide binary stellar systems under the strong finite-source effect, where the planet orbits one of the companions. From this, we find that the pattern of central perturbations in triple lens ... More
Detection of planets in extremely weak central perturbation microlensing events via next-generation ground-based surveysMar 06 2014Even though the recently discovered high-magnification event MOA-2010-BLG-311 had complete coverage over the peak, confident planet detection did not happen due to extremely weak central perturbations (fractional deviations of $\lesssim 2\%$). For confident ... More
A Planetary lensing feature in caustic-crossing high-magnification microlensing eventsMar 19 2012Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a ... More
A New Application of the Astrometric Method to Break Severe Degeneracies in Binary Microlensing EventsJan 28 2009Jan 29 2009When a source star is microlensed by one stellar component of a widely separated binary stellar components, after finishing the lensing event, the event induced by the other binary star can be additionally detected. In this paper, we investigate whether ... More
Microlensing Detections of Planets in Binary Stellar SystemsSep 13 2007We demonstrate that microlensing can be used for detecting planets in binary stellar systems. This is possible because in the geometry of planetary binary systems where the planet orbits one of the binary component and the other binary star is located ... More
Gravitational Microlensing: A Tool for Detecting and Characterizing Free-Floating PlanetsNov 18 2003Various methods have been proposed to search for extrasolar planets. Compared to the other methods, microlensing has unique applicabilities to the detections of Earth-mass and free-floating planets. However, the microlensing method is seriously flawed ... More
A Local Analysis of Block Coordinate Descent for Gaussian Phase RetrievalDec 06 2017While convergence of the Alternating Direction Method of Multipliers (ADMM) on convex problems is well studied, convergence on nonconvex problems is only partially understood. In this paper, we consider the Gaussian phase retrieval problem, formulated ... More
Limits of Binaries That Can Be Characterized by Gravitational MicrolensingAug 15 2008Due to the high efficiency of planet detections, current microlensing planet searches focus on high-magnification events. High-magnification events are sensitive to remote binary companions as well and thus a sample of wide-separation binaries are expected ... More
A Geometric Analysis of Phase RetrievalFeb 22 2016Mar 01 2016Can we recover a complex signal from its Fourier magnitudes? More generally, given a set of $m$ measurements, $y_k = |\mathbf a_k^* \mathbf x|$ for $k = 1, \dots, m$, is it possible to recover $\mathbf x \in \mathbb{C}^n$ (i.e., length-$n$ complex vector)? ... More
Complete Dictionary Recovery over the Sphere II: Recovery by Riemannian Trust-region MethodNov 15 2015Sep 01 2016We consider the problem of recovering a complete (i.e., square and invertible) matrix $\mathbf A_0$, from $\mathbf Y \in \mathbb{R}^{n \times p}$ with $\mathbf Y = \mathbf A_0 \mathbf X_0$, provided $\mathbf X_0$ is sufficiently sparse. This recovery ... More
Complete Dictionary Recovery over the SphereApr 26 2015Nov 17 2015We consider the problem of recovering a complete (i.e., square and invertible) matrix $\mathbf A_0$, from $\mathbf Y \in \mathbb R^{n \times p}$ with $\mathbf Y = \mathbf A_0 \mathbf X_0$, provided $\mathbf X_0$ is sufficiently sparse. This recovery problem ... More
Simultaneously continuous retraction and Bishop-Phelps-Bollobás type theoremAug 07 2013Apr 12 2014We study the existence of a retraction from the dual space $X^*$ of a (real or complex) Banach space $X$ onto its unit ball $B_{X^*}$ which is uniformly continuous in norm topology and continuous in weak-$*$ topology. Such a retraction is called a uniformly ... More
Estimating the Propagation of Interdependent Cascading Outages with Multi-Type Branching ProcessesMay 25 2014Aug 01 2016In this paper, the multi-type branching process is applied to describe the statistics and interdependencies of line outages, the load shed, and isolated buses. The offspring mean matrix of the multi-type branching process is estimated by the Expectation ... More
Closed-Form Solutions to A Category of Nuclear Norm Minimization ProblemsNov 22 2010Nov 23 2010It is an efficient and effective strategy to utilize the nuclear norm approximation to learn low-rank matrices, which arise frequently in machine learning and computer vision. So the exploration of nuclear norm minimization problems is gaining much attention ... More
Properties of Central Caustics in Planetary MicrolensingMay 18 2005May 20 2005To maximize the number of planet detections, current microlensing follow-up observations are focusing on high-magnification events which have a higher chance of being perturbed by central caustics. In this paper, we investigate the properties of central ... More
NASA ExoPAG Study Analysis Group 11: Preparing for the WFIRST Microlensing SurveySep 09 2014NASA's proposed WFIRST-AFTA mission will discover thousands of exoplanets with separations from the habitable zone out to unbound planets, using the technique of gravitational microlensing. The Study Analysis Group 11 of the NASA Exoplanet Program Analysis ... More
KMT-2016-BLG-1107: A New Hollywood-Planet Close/Wide DegeneracyMay 22 2018Nov 13 2018We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the planetary caustic. The planetary anomaly takes the form of a smooth, two-day ... More
Kmt-2016-blg-1397b: Kmtnet-only discovery of a microlens giant planetOct 25 2018We report the discovery of a giant planet in the KMT-2016-BLG-1397 microlensing event, which was found by The Korea Microlensing Telescope Network (KMTNet) alone. The time scale of this event is t_E = 40.0 +- 0.5 days and the mass ratio between the lens ... More
The Korea Microlensing Telescope Network (KMTNet) Alert Algorithm and Alert SystemJun 20 2018We describe a new microlensing-event alert algorithm that is tailored to the Korea Microlensing Telescope Network (KMTNet) multi-observatory system. The algorithm focuses on detecting "rising" events, i.e., events whose brightness is increasing as a function ... More
KMT-2016-BLG-1820 and KMT-2016-BLG-2142: Two Microlensing Binaries Composed of Planetary-mass Companions and Very-Low-Mass PrimariesMay 25 2018Sep 18 2018We present the analyses of two short-timescale $(t_{\rm E} \sim 5~{\rm days})$ microlensing events, KMT-2016-BLG-1820 and KMT-2016-BLG-2142. In both light curves, the brief anomalies were clearly captured and densely covered by the Korea Microlensing ... More
Mixture of Bilateral-Projection Two-dimensional Probabilistic Principal Component AnalysisJan 07 2016The probabilistic principal component analysis (PPCA) is built upon a global linear mapping, with which it is insufficient to model complex data variation. This paper proposes a mixture of bilateral-projection probabilistic principal component analysis ... More
The Bishop-Phelps-Bollobás point propertyMay 01 2016In this article, we study a version of the Bishop-Phelps-Bollob\'as property. We investigate a pair of Banach spaces $(X, Y)$ such that every operator from $X$ into $Y$ is approximated by operators which attains its norm at the same point where the original ... More
On a second numerical index for Banach spacesApr 21 2016We introduce a second numerical index for real Banach spaces with non-trivial Lie algebra, as the best constant of equivalence between the numerical radius and the quotient of the operator norm modulo the Lie algebra. We present a number of examples and ... More
Dual Modulation Faraday Rotation Spectroscopy of HO2Oct 10 2013The technique of dual modulation Faraday rotation spectroscopy has been applied for near shot-noise limited detection of HO2 at the exit of an atmospheric pressure flow reactor. This was achieved by combining direct current modulation at 51 kHz of an ... More
Selective Image Super-ResolutionOct 27 2010In this paper we propose a vision system that performs image Super Resolution (SR) with selectivity. Conventional SR techniques, either by multi-image fusion or example-based construction, have failed to capitalize on the intrinsic structural and semantic ... More
Mixed Effect Composite RNN-GP: A Personalized and Reliable Prediction Model for HealthcareJun 05 2018We present a personalized and reliable prediction model for healthcare, which can provide individually tailored medical services such as diagnosis, disease treatment and prevention. Our proposed framework targets to making reliable predictions from time-series ... More
KMT-2017-BLG-0165Lb: A Super-Neptune mass planet Orbiting a Sun-like Host StarSep 05 2018Dec 27 2018We report the discovery of a low mass-ratio planet $(q = 1.3\times10^{-4})$, i.e., 2.5 times higher than the Neptune/Sun ratio. The planetary system was discovered from the analysis of the KMT-2017-BLG-0165 microlensing event, which has an obvious short-term ... More
Scalable Steiner Tree for Multicast Communications in Software-Defined NetworkingApr 14 2014May 08 2014Software-Defined Networking (SDN) enables flexible network resource allocations for traffic engineering, but at the same time the scalability problem becomes more serious since traffic is more difficult to be aggregated. Those crucial issues in SDN have ... More
Properties of microlensing events by wide separation planets with a moonJun 02 2016We investigate the properties of microlensing events caused by planetary systems where planets with a moon are widely separated from their host stars. From this investigation, we find that the moon feature generally appears as an very short-duration perturbation ... More
KMT-2016-BLG-2052L: Microlensing Binary Composed of M Dwarfs Revealed from a Very Long Time-scale EventJul 30 2018We present the analysis of a binary microlensing event KMT-2016-BLG-2052, for which the lensing-induced brightening of the source star lasted for 2 seasons. We determine the lens mass from the combined measurements of the microlens parallax $\pie$ and ... More
Matrix product ansatz for Fermi fields in one dimensionJan 01 2015Mar 16 2015We present an implementation of a continuous matrix product state for two-component fermions in one-dimension. We propose a construction of variational matrices with an efficient parameterization that respects the translational symmetry of the problem ... More
Helical Majorana fermions in d_{x^2-y^2} + i d_{xy}-wave topological superconductivity of doped correlated quantum spin Hall insulatorsJun 08 2015Large Hubbard U limit of the Kane-Mele model on a zigzag ribbon of honeycomb lattice near half-filling is studied via a renormalized mean-field theory. The ground state exhibits time-reversal symmetry (TRS) breaking d + i d'-wave superconductivity. At ... More
Feasibility Study of Neutron Dose for Real Time Image Guided Proton Therapy: A Monte Carlo StudyMar 11 2015Two full rotating gantry with different nozzles (Multipurpose nozzle with MLC, Scanning Dedicated nozzle) with conventional cyclotron system is installed and under commissioning for various proton treatment options at Samsung Medical Center in Korea. ... More
Dislocation-induced thermal transport anisotropy in single-crystal group-III nitride filmsApr 09 2018Dislocations, one-dimensional lattice imperfections, are common to technologically important materials such as III-V semiconductors, and adversely affect heat dissipation in e.g., nitride-based high-power electronic devices. For decades, conventional ... More
Mechanical Controlled Thermal Switch and Hysteresis with Domain Boundary Engineered Phonon TransportOct 10 2013Heat flow control in phononics has received significant attention recently due to its widespread applications in energy transfer, conversion and utilization. Here, we demonstrate that by applying external stress or strain we can effectively tune the thermal ... More
Robust Low-Rank Subspace Segmentation with Semidefinite GuaranteesSep 20 2010Oct 08 2010Recently there is a line of research work proposing to employ Spectral Clustering (SC) to segment (group){Throughout the paper, we use segmentation, clustering, and grouping, and their verb forms, interchangeably.} high-dimensional structural data such ... More
A non-linear Bishop-Phelps-Bollobás type theoremJul 21 2017The main aim of this paper is to prove a Bishop-Phelps-Bollob\'as type theorem on the unital uniform algebra A_{w^*u}(B_{X^*}) consisting of all w^*-uniformly continuous functions on the closed unit ball B_{X^*} which are holomorphic on the interior of ... More
Dual-Reference Design for Holographic Coherent Diffraction ImagingFeb 07 2019A new reference design is introduced for Holographic Coherent Diffraction Imaging. This consists of two reference portions - being "block" and "pinhole" shaped regions - adjacent to the imaging specimen. Expected error analysis on data following a Poisson ... More
Gravitational Waves of Jet Precession in Gamma-ray BurstsApr 10 2012The physical nature of gamma-ray bursts (GRBs) are believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivate the idea of jet precession. In this work, we study the gravitational waves of jet precession based ... More
High-precision Absolute Distance Measurements over a Long Range Based on Two Optoelectronic OscillatorsOct 15 2012Absolute distance measurement (ADM) over a long range has been studied intensely over the last several decades, due to its important applications in large-scale manufacturing and outer space explorations [1-5]. Traditional absolute distance measurements ... More
Robust Recovery of Subspace Structures by Low-Rank RepresentationOct 14 2010May 06 2012In this work we address the subspace recovery problem. Given a set of data samples (vectors) approximately drawn from a union of multiple subspaces, our goal is to segment the samples into their respective subspaces and correct the possible errors as ... More
Capacity Enhanced Cooperative D2D Systems over Rayleigh Fading Channels with NOMAOct 16 2018This paper considers the cooperative device-to-device (D2D) systems with non-orthogonal multiple access (NOMA). We assume that the base station (BS) can communicate simultaneously with all users to satisfy the full information transmission. In order to ... More
Mechanical cooling in the single-photon quadratical optomechanicsApr 25 2015In the paper we study the nonlinear mechanical cooling processes in the intrinsic quadratically optomechanical coupling system without linearizing the optomechanical interaction. We apply the scattering theory to calculate the transition rates between ... More
Holographic Phase Retrieval and Optimal Reference DesignJan 19 2019A general mathematical framework and recovery algorithm is presented for the holographic phase retrieval problem. In this problem, which arises in holographic coherent diffraction imaging, a "reference" portion of the signal to be recovered via phase ... More
MOA-2016-BLG-319Lb: Microlensing Planet Subject to Rare Minor-Image Perturbation Degeneracy in Determining Planet ParameterSep 21 2018We present the analysis of the planetary microlensing event MOA-2016-BLG-319. The event light curve is characterized by a brief ($\sim 3$ days) anomaly near the peak produced by minor-image perturbations. From modeling, we find two distinct solutions ... More
Do Intermediate-Mass Black Holes Exist in Globular Clusters?Aug 13 2013The existence of intermediate-mass black holes (IMBHs) in globular clusters (GCs) remains a crucial problem. Searching IMBHs in GCs reveals a discrepancy between radio observations and dynamical modelings: the upper mass limits constrained by radio observations ... More
Impacts of a Supersonic Shock Front on Star Formation in the Bullet ClusterOct 07 2008We use the Bullet Cluster (1E0657-56) to investigate the extent to which star formation in cluster galaxies is influenced by ram pressure from supersonic gas (Mach 3) during a cluster merger. While the effects of ram pressure have been studied for individual ... More
Slow Molecules Produced by PhotodissociationMay 06 2009A simple method to control molecular translation with a chemical reaction is demonstrated. Slow NO molecules have been produced by partially canceling the molecular beam velocity of NO$_2$ with the recoil velocity of the NO photofragment. The NO$_2$ molecules ... More
Time evolution of flares in GRB 130925A: jet precession in black hole accretion systemJan 13 2014GRB 130925A, composed of three gamma-ray emission episodes and a series of orderly flares, has been detected by $Swift$, Fermi, Konus-$Wind$, and $INTEGRAL$. If the third weakest gamma-ray episode can be considered as a giant flare, we find that after ... More
Multi-Task Learning with a Fully Convolutional Network for Rectum and Rectal Cancer SegmentationJan 22 2019Feb 01 2019In a rectal cancer treatment planning, the location of rectum and rectal cancer plays an important role. The aim of this study is to propose a fully automatic method to segment both rectum and rectal cancer with axial T2-weighted magnetic resonance images. ... More
Cross-correlation search for continuous gravitational waves from a compact object in SNR 1987A in LIGO Science Run 5Sep 30 2016We present the results of a cross-correlation search for gravitational waves from SNR 1987A using the second year of LIGO Science Run 5 data. The frequency band 75--450\,Hz is searched. No evidence of gravitational waves is found. A 90\% confidence upper ... More
Doppler Shifts and Broadening and the Structure of the X-ray Emission from AlgolJan 27 2004In a study of Chandra High Energy Transmission Grating spectra of Algol, we clearly detect Doppler shifts caused by the orbital motion of Algol B. These data provide the first definitive proof that the X-ray emission of Algol is dominated by the secondary, ... More
Reconstruction of network structures from repeating spike patterns in simulated bursting dynamicsFeb 09 2014Jul 12 2014Repeating patterns of spike sequences from a neuronal network have been proposed to be useful in the reconstruction of the network topology. Reverberations in a physiologically realistic model with various physical connection topologies (from random to ... More
A Multi-layered Acoustic Tokenizing Deep Neural Network (MAT-DNN) for Unsupervised Discovery of Linguistic Units and Generation of High Quality FeaturesJun 07 2015This paper summarizes the work done by the authors for the Zero Resource Speech Challenge organized in the technical program of Interspeech 2015. The goal of the challenge is to discover linguistic units directly from unlabeled speech data. The Multi-layered ... More
$Spitzer$ Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-Rotating Low-Mass Brown DwarfMay 22 2018Jan 18 2019The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the mass and five of the six phase-space coordinates (all ... More
A Cold Neptune Beyond the Snow Line in the Provisional $\textit{WFIRST}$ FieldSep 28 2018We present the analysis of the microlensing event OGLE-2015-BLG-1670, detected in a high extinction field, very close to the Galactic plane. Due to the dust extinction along the line of sight, this event was too faint to be detected before it reached ... More
OGLE-2016-BLG-0156: Microlensing Event With Pronounced Microlens-Parallax Effects Yielding Precise Lens Mass MeasurementJan 19 2019We analyze the gravitational binary-lensing event OGLE-2016-BLG-0156, for which the lensing light curve displays pronounced deviations induced by microlens-parallax effects. The light curve exhibits 3 distinctive widely-separated peaks and we find that ... More
Spitzer Microlensing of MOA-2016-BLG-231L : A Counter-Rotating Brown Dwarf Binary in the Galactic DiskFeb 08 2019We analyze the binary microlensing event MOA-2016-BLG-231, which was observed from the ground and from Spitzer. The lens is composed of very low-mass brown dwarfs (BDs) with $M_1 = 21^{+12}_{-5} \ M_J$ and $M_2 = 9^{+5}_{-2}\ M_J$, and it is located in ... More
Spitzer Microlensing of MOA-2016-BLG-231L : A Counter-Rotating Brown Dwarf Binary in the Galactic DiskFeb 08 2019Feb 12 2019We analyze the binary microlensing event MOA-2016-BLG-231, which was observed from the ground and from Spitzer. The lens is composed of very low-mass brown dwarfs (BDs) with $M_1 = 21^{+12}_{-5} \ M_J$ and $M_2 = 9^{+5}_{-2}\ M_J$, and it is located in ... More
Global Uniform Boundedness of Solutions to viscous 3D Primitive Equations with Physical Boundary ConditionsOct 12 2017Oct 13 2017Global uniform boundedness of solutions to 3D viscous Primitive equations in a bounded cylindrical domain with physical boundary condition is proved in space $H^m$ for any $m\geqslant2$. A bounded absorbing set for the solutions in $H^m$ is obtained. ... More
Electronic structure in one-Fe Brillouin zone of iron-pnictide superconductor CsFe$_2$As$_2$Sep 08 2014Sep 09 2014The multiband nature of iron-pnictide superconductors is one of the keys to the understanding of their intriguing behavior. The electronic and magnetic properties heavily rely on the multiband interactions between different electron and hole pockets near ... More
Conetronics in 2D Metal-Organic Frameworks: Double Dirac Cones, Magnetic Half Dirac Cones and Quantum Anomalous Hall EffectJun 11 2016Based on recently synthesized Ni3C12S12 class 2D metal-organic frameworks, we predict electronic properties of M3C12S12 and M3C12O12, where M is Zn, Cd, Hg, Be, or Mg with no M orbital contributions to bands near Fermi level. For M3C12S12, their band ... More
Information Transfer in Swarms with LeadersJun 30 2014Swarm dynamics is the study of collections of agents that interact with one another without central control. In natural systems, insects, birds, fish and other large mammals function in larger units to increase the overall fitness of the individuals. ... More
Experimental determination of the elastic cotunneling rate in a hybrid single-electron boxJul 07 2014We report measurements of charge configurations and charge transfer dynamics in a hybrid single-electron box composed of aluminum and copper. We used two single-electron transistors (SETs) to simultaneously read out different parts of the box, enabling ... More
A W-test collapsing method for rare variant testing with applications to exome sequencing data of hypertensive disorderJul 26 2016Advancement in sequencing technology enables the study of association between complex disorders and rare variants with low minor allele frequencies. One of the major challenges in rare variant testing is lack of statistical power of traditional testing ... More
The Broadband and Spectrally-Resolved H-band Eclipse of KELT-1b and the Role of Surface Gravity in Stratospheric Inversions in Hot JupitersOct 11 2016We present a high precision H-band emission spectrum of the transiting brown dwarf KELT-1b, which we spectrophotometrically observed during a single secondary eclipse using the LUCI1 multi-object spectrograph on the Large Binocular Telescope. Using a ... More
Evolution of band structure from optimally doped to heavily overdoped Co-substituted NaFeAsJun 20 2012Using angle-resolved photoemission spectroscopy, we studied the electronic structure of NaFe$_{1-x}$Co$_x$As from an optimally doped superconducting compound ($x=0.028$) to a heavily overdoped non-superconducting one ($x=0.109$). Similar to the case of ... More
Monoclinic and Correlated Metal Phase in VO_2 as Evidence of the Mott Transition: Coherent Phonon AnalysisAug 03 2006In femtosecond pump-probe measurements, the appearance of coherent phonon oscillations at 4.5 THz and 6.0 THz indicating the rutile metal phase of VO_2 does not occur simultaneously with the first-order metal-insulator transition (MIT) near 68^oC. The ... More
Direct observation of laser guided corona dischargesAug 17 2015Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage ... More
A 95 GHz Class I Methanol Maser Survey Toward A Sample of GLIMPSE Point Sources Associated with BGPS ClumpsFeb 29 2012We report a survey with the Purple Mountain Observatory (PMO) 13.7-m radio telescope for class I methanol masers from the 95 GHz (8_0 - 7_1 A^+) transition. The 214 target sources were selected by combining information from both the Spitzer GLIMPSE and ... More
Electric field control of nonvolatile four-state magnetization at room temperatureNov 19 2011Mar 10 2012We find the realization of large converse magnetoelectric (ME) effects at room temperature in a multiferroic hexaferrite Ba$_{0.52}$Sr$_{2.48}$Co$_{2}$Fe$_{24}$O$_{41}$ single crystal, in which rapid change of electric polarization in low magnetic fields ... More
Optimal regularized inverse matrices for inverse problemsMar 18 2016In this paper, we consider optimal low-rank regularized inverse matrix approximations and their applications to inverse problems. We give an explicit solution to a generalized rank-constrained regularized inverse approximation problem, where the key novelties ... More
An Efficient Approach for Computing Optimal Low-Rank Regularized Inverse MatricesApr 06 2014Standard regularization methods that are used to compute solutions to ill-posed inverse problems require knowledge of the forward model. In many real-life applications, the forward model is not known, but training data is readily available. In this paper, ... More
Nonequilibrium finite-frequency noise of a resonance-level quantum dot close to a dissipative quantum phase transition: Functional Renormalization Group approachesOct 25 2010Nov 15 2012We calculate the finite-frequency current noise of a nonequilibrium resonance-level quantum dot close to a dissipative quantum phase transition of the Kosterlitz-Thouless (KT) type between a de-localized phase for weak dissipation and a localized phase ... More
Dynamical properties of a nonequilibrium quantum dot close to localized-delocalized quantum phase transitionsAug 23 2010We calculate the dynamical decoherence rate and susceptibility of a nonequilibrium quantum dot close to the delocalized-to-localized quantum phase transitions. The setup concerns a resonance-level coupled to two spinless fermionic baths with a finite ... More
Multilevel Monte Carlo Finite Element Method for A Stochastic Optimal Control ProblemDec 28 2015Jan 18 2016In this paper, we consider the implementation of multi-level Monte Carlo method to a stochastic optimal control problem with log-normal coefficients and its surrogate model problem. From the perspective of two optimization problems, i.e., minimizing the ... More
An Overlapping Domain Decomposition Preconditioner for the Helmholtz equationAug 12 2015In this paper, based on the overlapping domain decomposition method (DDM) proposed in \cite{Leng2015}, an one step preconditioner is proposed to solve 2D high frequency Helmholtz equation. The computation domain is decomposed in both $x$ and $y$ directions, ... More
Variational approach to nonlinear gravity-driven instabilities in a MHD settingSep 15 2005We establish a variational framework for nonlinear instabilities in a setting of the ideal magnetohydrodynamic (MHD) equations. We apply a variational method to various kind of smooth steady states which are shown to be nonlinearly unstable for both incompressible ... More
Coloring of graphs associated to zero-divisorsMar 02 2007Let $G$ be a graph, $\chi(G)$ be the minimal number of colors which can be assigned to the vertices of $G$ in such a way that every two adjacent vertices have different colors and $\omega(G)$ to be the least upper bound of the size of the complete subgraphs ... More
Ab initio optimization principle for the ground states of translationally invariant strongly correlated quantum lattice modelsDec 06 2015May 30 2016In this work, a simple and fundamental numeric scheme dubbed as ab-initio optimization principle (AOP) is proposed for the ground states of translational invariant strongly-correlated quantum lattice models. The idea is to transform a nondeterministic-polynomial-hard ... More
Quantum Properties of Cavity Cerenkov RadiationDec 28 2005Cerenkov radiation from cavities have been analyzed by quantum electrodynamic theory. Analytical expressions of some basic radiation properties including Einstein's $A$ and $B$ coefficients are derived and shown to be directly modified by the cavities. ... More
Limitation of multi-resolution methods in community detectionAug 22 2011Recently, a type of multi-resolution methods in community detection was introduced, which can adjust the resolution of modularity by modifying the modularity function with tunable resolution parameters, such as those proposed by Arenas, Fernandez and ... More
Optimal Resource Allocation in Full-Duplex Wireless-Powered Communication NetworkMar 11 2014Sep 15 2014This paper studies optimal resource allocation in the wireless-powered communication network (WPCN), where one hybrid access-point (H-AP) operating in full-duplex (FD) broadcasts wireless energy to a set of distributed users in the downlink (DL) and at ... More
A Hodge theoretic criterion for finite Weil--Petersson degenerations over a higher dimensional baseApr 23 2016We give a Hodge-theoretic criterion for a Calabi--Yau variety to have finite Weil--Petersson distance on higher dimensional bases up to a set of codimension $\geq 2$. The main tool is variation of Hodge structures and variation of mixed Hodge structures. ... More
Multidimensional Version of Lagrange's Problem on Mean MotionApr 10 2008Apr 14 2008The famous mean motion problem which goes back to Lagrange as follows: to prove that any exponential polynomial with exponents on the imaginary axis has an average speed for the amplitude, whenever the variable moves along a horizontal line. It was completely ... More
The multi-level Monte Carlo method for simulations of turbulent flowsAug 18 2016In this paper the application of the multi-level Monte Carlo (MLMC) method on numerical simulations of turbulent flows with uncertain parameters is investigated. Several strategies for setting up the MLMC method are presented, and the advantages and disadvantages ... More
Origin and Enhancement of Spin Polarization Current in Diluted Magnetic Oxides by Oxygen Vacancies and Nano Grain SizeNov 09 2015Spin polarized current is the main ingredient of diluted magnetic oxides due to its potential manipulation in spintronic devices. However, most research has focused on ferromagnetic properties rather than polarization of electric current, because direct ... More
A UV to Mid-IR Study of AGN SelectionFeb 21 2014We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 sq. deg Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR ... More
On Weyl modules over affine Lie algebras in prime characteristicOct 14 2013Jan 25 2016We construct a family of homomorphisms between Weyl modules for affine Lie algebras in characteristic p, which supports our conjecture on the strong linkage principle in this context. We also exhibit a large class of reducible Weyl modules beyond level ... More
User Cooperation in Wireless Powered Communication NetworksMar 27 2014Apr 07 2014This paper studies user cooperation in the emerging wireless powered communication network (WPCN) for throughput optimization. For the purpose of exposition, we consider a two-user WPCN, in which one hybrid access point (H-AP) broadcasts wireless energy ... More
Throughput Maximization in Wireless Powered Communication NetworksApr 30 2013Jul 21 2014This paper studies the newly emerging wireless powered communication network (WPCN) in which one hybrid access point (H-AP) with constant power supply coordinates the wireless energy/information transmissions to/from distributed users that do not have ... More
Surface bundles over surfaces with a fixed signatureNov 20 2015Jun 05 2016The signature of a surface bundle over a surface is known to be divisible by 4. It is also known that the signature vanishes if the fiber genus is less than or equal to 2 or the base genus is less than or equal to 1. In this article, we construct new ... More
Materials Informatics for Heat Transfer: Recent Progresses and PerspectivesJan 24 2019With the advances in materials and integration of electronics and thermoelectrics, the demand for novel crystalline materials with ultimate high/low thermal conductivity is increasing. However, search for optimal thermal materials is challenge due to ... More
Numerical study on diverging probability density function of flat-top solitons in an extended Korteweg-de Vries equationAug 15 2009We consider an extended Korteweg-de Vries (eKdV) equation, the usual Korteweg-de Vries equation with inclusion of an additional cubic nonlinearity. We investigate the statistical behaviour of flat-top solitary waves described by an eKdV equation in the ... More
Parity Violation in Top Quark Pair Production at the Fermilab Tevatron ColliderNov 18 1994The leading weak corrections to the production of top quark pairs via $q\bar{q} \to t\bar{t}$ in $p\bar{p}$ collisions are evaluated. The chromo-anapole form factor of the top quark and effects of parity violation are studied in the Standard Model (SM) ... More
Production of CP-Odd Higgs Bosons with Large Transverse Momentum at Hadron SupercollidersOct 01 1993Apr 05 1994A two Higgs doublet model is employed to study the production of a CP-odd Higgs boson ($A$) associated with a large transverse momentum jet ($j$) at hadron supercolliders. The cross section of $pp \to jA+X$ is evaluated with four subprocesses: $gg \to ... More
Sharp estimates for the commutator of the Hilbert transform on weighted Lebesgue spacesApr 21 2009Nov 22 2010This paper has been withdrawn by the author due to some error in the result
Diffusion-Driven Instability of a fourth order systemJul 03 2018We analyze diffusion-driven (Turing) instability of a reaction-diffusion system. The innovation is that we replace the traditional Laplacian diffusion operator with a combination of the fourth order bi-Laplacian operator and the second order Laplacian. ... More
Dynamics of Diffeomorphism Degrees of Freedom at a HorizonNov 02 2010Mar 19 2011We define a set of boundary conditions that ensure the presence of a null hypersurface with the essential characteristics of a horizon, using the formalism of weakly isolated horizons as a guide. We then determine the diffeomorphisms that preserve these ... More
The Study of Entangled States in Quantum Computation and Quantum Information ScienceAug 11 2008This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many areas of theoretical ... More