Results for "Kai-Xing Lu"

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A note on periodicity of long-term variations of optical continuum in active galactic nucleiApr 03 2016Graham et al. found a sample of active galactic nuclei (AGNs) and quasars from the Catalina Real-time Transient Survey (CRTS) that have long-term periodic variations in optical continuum, the nature of the periodicity remains uncertain. We investigate ... More
Reddening of the BLR and NLR in AGN From a Systematic Analysis of Balmer DecrementNov 27 2018Nov 29 2018We selected an active galactic nuclei (AGN) sample ($0 < z \le 0.35$) from Sloan Digital Sky Survey Data Release 7, and measured the broad- (${\rm H\alpha^{b}/H\beta^{b}}$) and narrow-line Balmer decrements (${\rm H\alpha^{n}/H\beta^{n}}$) of 554 selected ... More
Improving the Flux Calibration in Reverberation Mapping by Spectral Fitting: Application to the Seyfert Galaxy MCG--6-30-15Aug 24 2016We propose a method for the flux calibration of reverberation mapping spectra based on accurate measurement of [O III] $\lambda 5007$ emission by spectral fitting. The method can achieve better accuracy than the traditional method of van Groningen & Wanders ... More
The Fractional Chromatic Number of Triangle-free Graphs with $Δ\leq 3$Nov 10 2010Jul 25 2012Let $G$ be any triangle-free graph with maximum degree $\Delta\leq 3$. Staton proved that the independence number of $G$ is at least 5/14n. Heckman and Thomas conjectured that Staton's result can be strengthened into a bound on the fractional chromatic ... More
Monochromatic 4-term arithmetic progressions in 2-colorings of $\mathbb Z_n$Jul 14 2011This paper is motivated by a recent result of Wolf \cite{wolf} on the minimum number of monochromatic 4-term arithmetic progressions(4-APs, for short) in $\Z_p$, where $p$ is a prime number. Wolf proved that there is a 2-coloring of $\Z_p$ with 0.000386% ... More
High-order Phase Transition in Random HypergrpahsSep 03 2014Aug 02 2018In this paper, we study the high-order phase transition in random $r$-uniform hypergraphs. For a positive integer $n$ and a real $p\in [0,1]$, let $H:=H^r(n,p)$ be the random $r$-uniform hypergraph with vertex set $[n]$, where each $r$-set is selected ... More
Loose Laplacian spectra of random hypergraphsSep 15 2011Dec 05 2011Let $H=(V,E)$ be an $r$-uniform hypergraph with the vertex set $V$ and the edge set $E$. For $1\leq s \leq r/2$, we define a weighted graph $G^{(s)}$ on the vertex set ${V\choose s}$ as follows. Every pair of $s$-sets $I$ and $J$ is associated with a ... More
Spectra of edge-independent random graphsApr 27 2012Let $G$ be a random graph on the vertex set $\{1,2,..., n\}$ such that edges in $G$ are determined by independent random indicator variables, while the probability $p_{ij}$ for $\{i,j\}$ being an edge in $G$ is not assumed to be equal. Spectra of the ... More
High-ordered Random Walks and Generalized Laplacians on HypergraphsFeb 22 2011Despite of the extreme success of the spectral graph theory, there are relatively few papers applying spectral analysis to hypergraphs. Chung first introduced Laplacians for regular hypergraphs and showed some useful applications. Other researchers treated ... More
High-order Phase Transition in Random HypergrpahsSep 03 2014In this paper, we study the high-order phase transition in random $r$-uniform hypergraphs. For a positive integer $n$ and a real $p\in [0,1]$, let $H:=H^r(n,p)$ be the random $r$-uniform hypergraph on the vertex set $[n]$, where each $r$-set is an edge ... More
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. III. Detection of Fe II Reverberation in Nine Narrow-Line Seyfert 1 GalaxiesMar 12 2015This is the third in a series of papers reporting on a large reverberation-mapping campaign aimed to study the properties of active galactic nuclei (AGNs) with high accretion rates. We present new results on the variability of the optical Fe II emission ... More
Higher-Derivative Gravity with Non-minimally Coupled Maxwell FieldDec 30 2015We construct higher-derivative gravities with a non-minimally coupled Maxwell field. The Lagrangian consists of polynomial invariants built from the Riemann tensor and the Maxwell field strength in such a way that the equations of motion are second order ... More
Supermassive black holes with high accretion rates in active galactic nuclei: II. the most luminous standard candles in the UniverseAug 11 2014This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting massive black holes ... More
The Correlation Potential of a Test Ion Near a Strongly Charged PlateNov 01 2013Mar 15 2014We analytically calculate the correlation potential of a test ion near a \emph{strongly} charged plate inside a dilute $m:-n$ electrolyte. We do this by calculating the electrostatic Green's function in the presence of a nonlinear background potential, ... More
One-party Quantum Error Correcting Codes for Unbalanced Errors: Principles and Application to Quantum Dense Coding and Quantum Secure Direct CommunicationsSep 27 2006Feb 28 2007In this article, we present the unbalanced quantum error correcting codes(one-party-QECC), a novel idea for correcting unbalanced quantum errors. In some quantum communication tasks using entangled pairs, the error distributions between two parts of the ... More
Secure Ping-Pong quantum key distribution protocol with 33.3% bit error rateDec 12 2005Sep 27 2006This paper has been withdrawn and replaced by quant-ph/0609207.
Supermassive black holes with high accretion rates in active galactic nuclei: X. Optical variability characteristicsApr 06 2019We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns including our ongoing campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs). This sample covers a large range ... More
Spectroscopic Indication for a Centi-parsec Supermassive Black Hole Binary in the Galactic Center of NGC 5548Feb 16 2016Mar 04 2016As a natural consequence of cosmological hierarchical structure formation, sub-parsec supermassive black hole binaries (SMBHBs) should be common in galaxies but thus far have eluded spectroscopic identification. Based on four decades of optical spectroscopic ... More
Reverberation mapping of narrow-line Seyfert 1 galaxy I Zwicky 1: black hole massApr 12 2019We report results of the first reverberation mapping campaign of I Zwicky 1 during $2014$-$2016$, which showed unambiguous reverberations of the broad H$\beta$ line emission to the varying optical continuum. From analysis using several methods, we obtain ... More
A High-Quality velocity-delay map of the broad-line region in NGC 5548Sep 15 2018Sep 18 2018NGC 5548 has been well spectroscopically monitored for reverberation mapping of the central kinematics by 19 campaigns. Using the maximum entropy method in this Letter, we build up a high-quality velocity-delay map of the H$\beta$ emission line in the ... More
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IX 10 New Observations of Reverberation Mapping and Shortened H$β$ LagsFeb 08 2018As one of the series of papers reporting on a large reverberation mapping campaign of super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs), we present the results of 10 SEAMBHs monitored spectroscopically during 2015-2017. ... More
A Possible ~20-Year Periodicity in Long-term Variations of the Nearby Radio-Quiet Active Galactic Nucleus Ark 120May 22 2017We report a possible periodicity in the long-term monitoring of Ark 120, a nearby radio-quiet active galactic nucleus (AGN) at a distance of 143 Mpc (z=0.03271). We compile the historic archival photometric and spectroscopic data of Ark 120 since 1974 ... More
Visualized Insights into the Optimization Landscape of Fully Convolutional NetworksJan 20 2019Many image processing tasks involve image-to-image mapping, which can be addressed well by fully convolutional networks (FCN) without any heavy preprocessing. Although empirically designing and training FCNs can achieve satisfactory results, reasons for ... More
The super-super exchange mechanism in iron-based antiperovskite chalco-halidesApr 07 2016By using the first-principles electronic structure calculations, we have systematically studied the magnetism in three recently synthesized iron-based antiperovskite chalco-halides: Ba$_3$(FeS$_4$)Cl, Ba$_3$(FeS$_4$)Br, and Ba$_3$(FeSe$_4$)Br. These compounds ... More
Reverberation Mapping of the Broad-line Region in NGC 5548: Evidence for Radiation Pressure?Jul 27 2016NGC 5548 is the best-observed reverberation-mapped active galactic nucleus with long-term, intensive monitoring. Here we report results from a new observational campaign between January and July, 2015. We measure the centroid time lag of the broad H$\beta$ ... More
Cooperative Multi-Agent Policy Gradients with Sub-optimal DemonstrationDec 05 2018Many reality tasks such as robot coordination can be naturally modelled as multi-agent cooperative system where the rewards are sparse. This paper focuses on learning decentralized policies for such tasks using sub-optimal demonstration. To learn the ... More
Charged Plate in Asymmetric Electrolytes: One-loop Renormalization of Surface Charge Density and Debye Length due to Ionic CorrelationsFeb 12 2016The self-consistent field theory (SCFT) is used to study the mean potential near a charged plate inside a $m:-n$ electrolyte. A perturbation series is developed in terms of $g = 4 \pi b/\ell_{\rm {\scriptscriptstyle DB}}$, where $b, \ell_{\rm{\scriptscriptstyle ... More
A Fractional Analogue of Brooks' TheoremMar 17 2011Nov 13 2011Let $\Delta(G)$ be the maximum degree of a graph $G$. Brooks' theorem states that the only connected graphs with chromatic number $\chi(G)=\Delta(G)+1$ are complete graphs and odd cycles. We prove a fractional analogue of Brooks' theorem in this paper. ... More
Holographic Complexity and Two Identities of Action GrowthNov 07 2016Nov 23 2016The recently proposed complexity-action conjecture allows one to calculate how fast one can produce a quantum state from a reference state in terms of the on-shell action of the dual AdS black hole at the Wheeler-DeWitt patch. We show that the action ... More
Equivalent classes in matching covered graphsFeb 25 2019Let $G$ be a matching covered graph. Two edges $ e_1$ and $e_2$ of $G$ are {\it equivalent} if $\{e_1,e_2\}\subseteq M$ or $\{e_1,e_2\}\cap M=\emptyset$ for every perfect matching $M$ of $G$. An {\it equivalent class} of $G$ is an edge set $S$ of $G$ ... More
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. VIII. Structure of the Broad-Line Region and Mass of the Central Black Hole in Mrk 142Nov 15 2018This is the eighth in a series of papers reporting on a large reverberation mapping campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). We employ the recently developed dynamical modeling approach for broad-line ... More
Scalar Hairy Black Holes in General DimensionsDec 18 2013Jan 13 2014We obtain a class of asymptotic flat or (A)dS hairy black holes in D-dimensional Einstein gravity coupled to a scalar with certain scalar potential. For a given mass, the theory admits both the Schwarzschild-Tangherlini and the hairy black holes with ... More
Electronic structures of quasi-one-dimensional cuprate superconductors Ba$_2$CuO$_{3+δ}$Jan 31 2019An intact CuO$_2$ plane is widely believed to be a prerequisite for the high-$T_c$ superconductivity in cuprate superconductors. However, an exception may exist in the superconducting Ba$_2$CuO$_{3+\delta}$ materials where CuO chains play a more important ... More
RLS-Based Adaptive Dereverberation Tracing Abrupt Position Change of Target SpeakerFeb 25 2018Aug 23 2018Adaptive algorithm based on multi-channel linear prediction is an effective dereverberation method balancing well between the attenuation of the long-term reverberation and the dereverberated speech quality. However, the abrupt change of the speech source ... More
Fast 3D Line Segment Detection From Unorganized Point CloudJan 08 2019This paper presents a very simple but efficient algorithm for 3D line segment detection from large scale unorganized point cloud. Unlike traditional methods which usually extract 3D edge points first and then link them to fit for 3D line segments, we ... More
Discrete-Time Output-Feedback Robust Repetitive Control for a Class of Nonlinear Systems by Additive State DecompositionJan 08 2014The discrete-time robust repetitive control (RC, or repetitive controller, also designated RC) problem for nonlinear systems is both challenging and practical. This paper proposes a discrete-time output-feedback RC design for a class of systems subject ... More
Hyper-parameter Tuning under a Budget ConstraintFeb 01 2019We study a budgeted hyper-parameter tuning problem, where we optimize the tuning result under a hard resource constraint. We propose to solve it as a sequential decision making problem, such that we can use the partial training progress of configurations ... More
Novel Fermi Liquid of 2D Polar MoleculesNov 30 2011We study Fermi liquid properties of a weakly interacting 2D gas of single-component fermionic polar molecules with dipole moments $d$ oriented perpendicularly to the plane of their translational motion. This geometry allows the minimization of inelastic ... More
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. VI. Velocity-resolved Reverberation Mapping of H$β$ LineFeb 05 2016In the sixth of the series of papers reporting on a large reverberation mapping (RM) campaign of active galactic nuclei (AGNs) with high accretion rates, we present velocity-resolved time lags of H$\beta$ emission lines for nine objects observed in the ... More
Frequency domain TRINICON-based blind source separation method with multi-source activity detection for sparsely mixed signalsFeb 25 2018The TRINICON ('Triple-N ICA for convolutive mixtures') framework is an effective blind signal separation (BSS) method for separating sound sources from convolutive mixtures. It makes full use of the non-whiteness, non-stationarity and non-Gaussianity ... More
Supermassive black holes with high accretion rates in active galactic nuclei. VII. Reconstruction of velocity-delay maps by maximum entropy methodAug 02 2018As one of the series of papers reporting on a large reverberation mapping campaign, we apply the maximum entropy method (MEM) to 9 narrow-line Seyfert 1 galaxies with super-Eddington accretion rates observed during 2012-2013 for the velocity-delay maps ... More
Optical and Gamma-Ray Variability Behaviors of 3C 454.3 from 2006 to 2011Feb 15 2018We present our photometric monitoring of a flat spectrum radio quasar (FSRQ) 3C 454.3 at Yunnan observatories from 2006 to 2011. We find that the optical color of 3C 454.3 shows obvious redder-when-brighter trend, which reaches a saturation stage when ... More
To Harvest and Jam: A Paradigm of Self-Sustaining Friendly Jammers for Secure AF RelayingFeb 25 2015Oct 21 2015This paper studies the use of multi-antenna harvest-and-jam (HJ) helpers in a multi-antenna amplify-and-forward (AF) relay wiretap channel assuming that the direct link between the source and destination is broken. Our objective is to maximize the secrecy ... More
Evolution of individual quantum Hall edge states in the presence of disorderMay 13 2018Employing the Bloch eigenmode matching approach, we numerically study the evolution of individual quantum Hall edge states with respect to disorder. As shown by the two-parameter renormalization group flow of the Hall and Thouless conductances, quantum ... More
Decoupled Heterogeneous Networks with Millimeter Wave Small CellsNov 02 2017Deploying sub-6GHz network together with millimeter wave (mmWave) is a promising solution to simultaneously achieve sufficient coverage and high data rate. In the heterogeneous networks (HetNets), the traditional coupled access, i.e., the users are constrained ... More
Factorization Violation and Scale InvarianceJan 03 2018May 26 2018Factorization violating effects in hadron scattering are due mainly to spectator-spectator interactions. While it is known that these interactions cancel in inclusive cross sections, like for the Drell-Yan process, not much is known about for what classes ... More
Optimizing DF Cognitive Radio Networks with Full-Duplex-Enabled Energy Access PointsNov 16 2016Mar 28 2017With the recent advances in radio frequency (RF) energy harvesting (EH) technologies, wireless powered cooperative cognitive radio network (CCRN) has drawn an upsurge of interest for improving the spectrum utilization with incentive to motivate joint ... More
Wireless Powered Cooperative Jamming for Secrecy Multi-AF Relaying NetworksNov 11 2015This paper studies secrecy transmission with the aid of a group of wireless energy harvesting (WEH)-enabled amplify-and-forward (AF) relays performing cooperative jamming (CJ) and relaying. The source node in the network does simultaneous wireless information ... More
YouSense: Mitigating Entropy Selfishness in Distributed Collaborative Spectrum SensingNov 22 2011Mar 21 2013Collaborative spectrum sensing has been recognized as a promising approach to improve the sensing performance via exploiting the spatial diversity of the secondary users. In this study, a new selfishness issue is identified, that selfish users sense no ... More
Collinear factorization violation and effective field theoryMar 24 2017The factorization of amplitudes into hard, soft and collinear parts is known to be violated in situations where incoming particles are collinear to outgoing ones. This result was first derived by studying limits where non-collinear particles become collinear. ... More
Atomic and electronic structures of FeSe monolayer and bilayer thin films on SrTiO$_3$ (001): a first-principles studyFeb 02 2012Feb 06 2012By the first-principles electronic structure calculations, we have studied electronic structures of FeSe monolayer and bilayer thin films on SrTiO$_3$ (001) with SrO-termination or TiO$_2$ termination. We find that both FeSe monolayer and bilayer on either ... More
Nematic antiferromagnetic states in bulk FeSeOct 26 2015We revisit bulk FeSe through the systematic first-principles electronic structure calculations. We find that there are a series of staggered $n$-mer antiferromagnetic (AFM) states with corresponding energies below that of the collinear AFM state which ... More
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line RegionApr 21 2016This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014-2015. Ten new targets were selected from quasar sample of Sloan Digital Sky Survey ... More
Robust topological edge states at the perfect surface step edge of topological insulator ZrTe$_5$Jan 22 2016We report an atomic-scale characterization of ZrTe$_5$ by using scanning tunneling microscopy. We observe a bulk bandgap of ~80 meV with topological edge states at the step edge, and thus demonstrate ZrTe$_5$ is a two dimensional topological insulator. ... More
A Possible ~20-Year Periodicity in Long-term Optical Photometric and Spectral Variations of the Nearby Radio-Quiet Active Galactic Nucleus Ark 120May 22 2017Mar 13 2019We study the long-term variability in the optical monitoring database of Ark 120, a nearby radio-quiet active galactic nucleus (AGN) at a distance of 143 Mpc (z=0.03271). We compiled the historical archival photometric and spectroscopic data since 1974 ... More
Statistical physics of isotropic-genesis nematic elastomers: I. Structure and correlations at high temperaturesApr 14 2013Isotropic-genesis nematic elastomers (IGNEs) are liquid crystalline polymers (LCPs) that have been randomly, permanently cross-linked in the high-temperature state so as to form an equilibrium random solid. Thus, instead of being free to diffuse throughout ... More
Generalized Deam-Edwards Approach to the Statistical Mechanics of Randomly Crosslinked SystemsMay 03 2013We address the statistical mechanics of randomly and permanently crosslinked networks. We develop a theoretical framework (vulcanization theory) which can be used to systematically analyze the correlation between the statistical properties of random networks ... More
Rotating Solutions in Critical Lovelock GravitiesSep 28 2016For appropriate choices of the coupling constants, the equations of motion of Lovelock gravities up to order n in the Riemann tensor can be factorized such that the theories admits a single (A)dS vacuum. In this paper we construct two classes of exact ... More
Improving Deep Pancreas Segmentation in CT and MRI Images via Recurrent Neural Contextual Learning and Direct Loss FunctionJul 16 2017Jul 18 2017Deep neural networks have demonstrated very promising performance on accurate segmentation of challenging organs (e.g., pancreas) in abdominal CT and MRI scans. The current deep learning approaches conduct pancreas segmentation by processing sequences ... More
The Integrated Sachs-Wolfe Effect in Time Varying Vacuum ModelApr 20 2010The integrated Sachs-Wolfe (ISW) effect is an important implication for dark energy. In this paper, we have calculated the power spectrum of the ISW effect in the time varying vacuum cosmological model, where the model parameter $\beta=4.407$ is obtained ... More
A Novel Rate and Channel Control Scheme Based on Data Extraction Rate for LoRa NetworksFeb 12 2019Long Range (LoRa) has become one of the most popular Low Power Wide Area (LPWA) technologies, which provides a desirable trade-off among communication range, battery life, and deployment cost. In LoRa networks, several transmission parameters can be allocated ... More
Multiscale Technicolor and the Zbb-bar VertexSep 28 1995We estimate the correction to the Zbb-bar vertex arising from the exchanges of the sideways extended technicolor (ETC) boson and the flavor-diagonal ETC boson in the multiscale walking technicolor model. The obtained result is too large to explain the ... More
Fragmentation of Molecular Clumps and Formation of ProtoclusterMar 10 2015Sufficiently massive clumps of molecular gas collapse under self-gravity and fragment to spawn a cluster of stars that have a range of masses. We investigate observationally the early stages of formation of a stellar cluster in a massive filamentary infrared ... More
Godel Universe from String TheoryDec 06 2016Dec 12 2016G\"odel universe is a direct product of a line and a three-dimensional spacetime we call G$_\alpha$. In this paper, we show that the G\"odel metrics can arise as exact solutions in Einstein-Maxwell-Axion, Einstein-Proca-Axion, or Freedman-Schwarz gauged ... More
Modeling and Performance Analysis of Pull-Based Live Streaming Schemes in Peer-to-Peer NetworkFeb 17 2013Recent years mesh-based Peer-to-Peer live streaming has become a promising way for service providers to offer high-quality live video streaming service to Internet users. In this paper, we make a detailed study on modeling and performance analysis of ... More
Anisotropic deformation of Rydberg blockade sphere in few-atom systemsSep 02 2013Rydberg blockade sphere persists an intriguing picture by which a number of collective many-body effects caused by the strong Rydberg-Rydberg interactions can be clearly understood and profoundly investigated. In the present work, we develop a new definition ... More
Initial Fragmentation in the Infrared Dark Cloud G28.53-0.25Mar 30 2015To study the fragmentation and gravitational collapse of dense cores in infrared dark clouds (IRDCs), we have obtained submillimeter continuum and spectral line data as well as multiple inversion transitions of NH3 and H2O maser data of four massive clumps ... More
Phenomenological Theory of Isotropic-Genesis Nematic ElastomersMar 05 2012We consider the impact of the elastomer network on the structure and fluctuations in the isotropic-genesis nematic elastomer, via a phenomenological model that underscores the role of network compliance. The model contains a network-mediated nonlocal ... More
Polydomain structure and its origins in isotropic-genesis nematic elastomersJan 06 2011We address the physics of nematic liquid crystalline elastomers randomly crosslinked in the isotropic state. To do this, we construct a phenomenological effective replica Hamiltonian in terms of two order-parameter fields: one for the vulcanization, the ... More
Charge Renormalization and Charge Oscillation in Asymmetric Primitive ModelFeb 24 2015Feb 19 2016The Debye charging method is generalized to study the linear response properties of the asymmetric primitive model for electrolytes. Analytic results are obtained for the effective charge distributions of constituent ions inside the electrolyte, from ... More
High temperature superconducting phase of HBr under pressure predicted by first-principles calculationsAug 14 2017The high pressure phases of HBr are explored with an ab initio crystal structure search. By taking into account the contribution of zero-point energy (ZPE), we find that the P4/nmm phase of HBr is thermodynamically stable in the pressure range from 150 ... More
A Unified Mechanism for Hydrogen Trapping at Metal VacanciesNov 05 2013Interaction between hydrogen (H) and metals is central to many materials problems of scientific and technological importance. Chief among them is the development of H storage and H-resistant materials. H segregation or trapping at lattice defects, including ... More
Multifractal characteristics and return predictability in the Chinese stock marketsJun 20 2018By adopting Multifractal detrended fluctuation (MF-DFA) analysis methods, the multifractal nature is revealed in the high-frequency data of two typical indexes, the Shanghai Stock Exchange Composite 180 Index (SH180) and the Shenzhen Stock Exchange Composite ... More
Boron Nitride Nanosheets for Metal ProtectionMar 04 2015Although the high impermeability of graphene makes it an excellent barrier to inhibit metal oxidation and corrosion, graphene can form a galvanic cell with the underlying metal that promotes corrosion of the metal in the long term. Boron nitride (BN) ... More
Bounce Universe and Black Holes from Critical Einsteinian Cubic GravityJul 19 2017We show that there exists a critical point for the coupling constants in Einsteinian cubic gravity where the linearized equations on the maximally-symmetric vacuum vanish identically. We construct an exact isotropic bounce universe in the critical theory ... More
Time Machines and AdS Solitons with Negative MassDec 30 2016We show that in D=2n+1 dimensions, when mass is negative and all angular momenta are non-vanishing, Kerr and Kerr-AdS metrics describe smooth time machines, with no curvature singularity. Turning off the angular momenta appropriately can lead to static ... More
Efficient Graph Edit Distance Computation and Verification via Anchor-aware Lower Bound EstimationSep 20 2017Oct 01 2017Graph edit distance (GED) is an important similarity measure adopted in a similarity-based analysis between two graphs, and computing GED is a primitive operator in graph database analysis. Partially due to the NP-hardness, the existing techniques for ... More
X-LoRa: An Open Source LPWA NetworkDec 21 2018Jan 26 2019Long Range (LoRa) network is emerging as one of the most promising systems in Low power wide area (LPWA) networks, since it enables the energy-constraint devices distributed over wide areas to establish affordable connectivity. Although the LoRa technology ... More
Reconstructing Dark Energy Potentials From Parameterized Deceleration ParametersApr 20 2010In this paper, the properties of dark energy are investigated according to the parameterized deceleration parameter $q(z)$, which is used to describe the extent of the accelerating expansion of the universe. The potential of dark energy $V(\phi)$ and ... More
Distributed interaction between computer virus and patch: A modeling studyMay 13 2017The decentralized patch distribution mechanism holds significant promise as an alternative to its centralized counterpart. For the purpose of accurately evaluating the performance of the decentralized patch distribution mechanism and based on the exact ... More
Multifractal cross wavelet analysisOct 29 2016Feb 25 2018Complex systems are composed of mutually interacting components and the output values of these components are usually long-range cross-correlated. We propose a method to characterize the joint multifractal nature of such long-range cross correlations ... More
First-principles study of FeSe epitaxial films on SrTiO3Oct 29 2015The discovery of high temperature superconductivity in FeSe films on SrTiO3 substrate has inspired great experimental and theoretical interests. First-principles density functional theory calculations, which have played an important role in the study ... More
First-principles study of magnetic frustration in FeSe epitaxial films on SrTiO$_3$Jan 16 2015The effects of electron doping and phonon vibrations on the magnetic properties of monolayer and bilayer FeSe epitaxial films on SrTiO$_3$ have been studied, respectively, using first-principles calculations with van der Waals correction. For monolayer ... More
Intrinsic Origin of Enhancement of Ferroelectricity in SnTe Ultrathin FilmsMay 10 2018Previous studies showed that, as ferroelectric films become thinner, their Curie temperature (Tc) and polarization below Tc both typically decrease. In contrast, a recent experiment [Chang et al., Science 353, 274 (2016)] observed that atomic-thick SnTe ... More
Counterexamples for Robotic Planning Explained in Structured LanguageMar 23 2018Automated techniques such as model checking have been used to verify models of robotic mission plans based on Markov decision processes (MDPs) and generate counterexamples that may help diagnose requirement violations. However, such artifacts may be too ... More
Exploring the Partially-obscured BLR and Partially-covered NLRFeb 25 2009We have conducted a series of investigations on the geometry of the reddening material in AGNs, which have important implications to the AGN unification and SMBH demography. According to our statistics of partially obscured quasars, we found that SMBHs ... More
Secure Reusable Base-String in Quantum Key DistributionJun 26 2007Protecting secure random key from eavesdropping in quantum key distribution protocols has been well developed. In this letter, we further study how to detect and eliminate eavesdropping on the random base string in such protocols. The correlation between ... More
Merging the Bernoulli-Gaussian and Symmetric Alpha-Stable Models for Impulsive Noises in Narrowband Power Line ChannelsOct 25 2017Jan 08 2019To model impulsive noise in power line channels, both the Bernoulli-Gaussian model and the symmetric alpha-stable model are usually applied. Towards a merge of existing noise measurement databases and a simplification of communication system design, the ... More
Resonance of Gaussian electromagnetic field to the high frequency gravitational wavesNov 07 2014May 28 2016We consider a Gaussian Beam (GB) resonant system for high frequency gravitational waves (HFGWs) detection. At present, we find the optimal signal strength in theory through setting the magnetic component of GB in a standard gaussian form. Under the synchro-resonance ... More
Surface Plasmonic Lattice Solitons in Semi-infinite Graphene Sheet ArraysNov 21 2016We investigate the surface plasmonic lattice solitons (PLSs) in semi-infinite graphene sheet arrays. The surface soliton is formed as the SPPs tunneling is inhibited by the graphene nonlinearity, and meanwhile the incident power should be above a threshold ... More
One-Lee weight and two-Lee weight $\mathbb{Z}_2\mathbb{Z}_2[u]$-additive codesSep 30 2016Feb 02 2018In this paper, we study one-Lee weight and two-Lee weight codes over $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$, where $u^{2}=0$. Some properties of one-Lee weight $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$-additive codes are given, and a complete classification of one-Lee ... More
Zero sound in a two-dimensional dipolar Fermi gasJul 15 2013We study zero sound in a weakly interacting 2D gas of single-component fermionic dipoles (polar molecules or atoms with a large magnetic moment) tilted with respect to the plane of their translational motion. It is shown that the propagation of zero sound ... More
Quantum Hall effects in a Weyl Semi-Metal: possible application in pyrochlore IridatesMay 12 2011May 27 2011There have been lots of interest in pyrochlore Iridates A2Ir2O7 where both strong spin-orbital coupling and strong correlation are present. A recent LDA calculation suggests that the system is likely in a novel three dimensional topological semi-metallic ... More
The influence of spin-phonon coupling on antiferromagnetic spin fluctuations in FeSe under pressure: the First-principles calculations with van der Waals correctionsSep 10 2013The electronic structures, lattice dynamics, and magnetic properties of crystal {\beta}-FeSe under hydrostatic pressure have been studied by using the first-principles electronic structure calculations with van der Waals (vdW) corrections. With applied ... More
Tuning the magnetism of the top-layer FeAs on BaFe$_{2}$As$_{2}$(001): First-principles studyAug 01 2017The magnetic properties of BaFe$_{2}$As$_{2}$(001) surface have been studied by using first-principles electronic structure calculations. We find that for As-terminated surface the magnetic ground state of the top-layer FeAs is in the staggered dimer ... More
Laterally emitted surface second harmonic generation in a single ZnTe nanowireNov 15 2012Apr 16 2013We report a direct observation on the unique laterally emitted surface second harmonic generation (SHG) in a single ZnTe nanowire. The highly directional surface SHG signal that polarizes along the direction vertical to the nanowire growth axis, is significantly ... More
A Novel Sub-Nyquist Multiband Signal Detection Algorithm for Cognitive RadioFeb 12 2018Wideband spectrum sensing (WSS) is an essential technology for cognitive radio. However, the sampling rate is still a bottleneck of WSS. Several sub-Nyquist sensing methods have been proposed. These technologies deteriorate in the low signal to noise ... More
Vertex Priority Based Butterfly Counting for Large-scale Bipartite NetworksDec 01 2018Bipartite networks are of great importance in many real-world applications. In bipartite networks, butterfly (i.e., a complete 2 x 2 biclique) is the smallest non-trivial cohesive structure and plays a key role. In this paper, we study the problem of ... More
Towards Universal Dialogue State TrackingOct 22 2018Dialogue state tracking is the core part of a spoken dialogue system. It estimates the beliefs of possible user's goals at every dialogue turn. However, for most current approaches, it's difficult to scale to large dialogue domains. They have one or more ... More
Modeling and Simulation for Fluid-Rotating Structure InteractionOct 17 2015Nov 05 2015In this paper, we study a dynamic fluid-structure interaction (FSI) model for an elastic structure that is immersed and spinning in the fluid. We develop a linear constitutive model to describe the motion of a rotational elastic structure which is suitable ... More