arXiv subjects

Su Wang

Publications and source records attributed to Su Wang.

At least 91 records · Page 5Linked to original sources

arXiv2019

Query-Focused Scenario Construction

The news coverage of events often contains not one but multiple incompatible accounts of what happened. We develop a query-based system that extracts compatible sets of events (scenarios) from such data, formulated as one-class clustering. Our system incrementally evaluates each event's compatibility with already selected events, taking order into account. We use synthetic data consisting of article mixtures for scalable training and evaluate our model on a new human-curated dataset of scenarios about real-world news topics. Stronger neural network models and harder synthetic training settings are both important to achieve high performance, and our final scenario construction system substantially outperforms baselines based on prior work.

cs.CL↗

arXiv2018

A task in a suit and a tie: paraphrase generation with semantic augmentation

Paraphrasing is rooted in semantics. We show the effectiveness of transformers (Vaswani et al. 2017) for paraphrase generation and further improvements by incorporating PropBank labels via a multi-encoder. Evaluating on MSCOCO and WikiAnswers, we find that transformers are fast and effective, and that semantic augmentation for both transformers and LSTMs leads to sizable 2-3 point gains in BLEU, METEOR and TER. More importantly, we find surprisingly large gains on human evaluations compared to previous models. Nevertheless, manual inspection of generated paraphrases reveals ample room for improvement: even our best model produces human-acceptable paraphrases for only 28% of captions from the CHIA dataset (Sharma et al. 2018), and it fails spectacularly on sentences from Wikipedia. Overall, these results point to the potential for incorporating semantics in the task while highlighting the need for stronger evaluation.

cs.CL↗

arXiv2018

Picking Apart Story Salads

During natural disasters and conflicts, information about what happened is often confusing, messy, and distributed across many sources. We would like to be able to automatically identify relevant information and assemble it into coherent narratives of what happened. To make this task accessible to neural models, we introduce Story Salads, mixtures of multiple documents that can be generated at scale. By exploiting the Wikipedia hierarchy, we can generate salads that exhibit challenging inference problems. Story salads give rise to a novel, challenging clustering task, where the objective is to group sentences from the same narratives. We demonstrate that simple bag-of-words similarity clustering falls short on this task and that it is necessary to take into account global context and coherence.

cs.CL↗

arXiv2018

Investigation of Thermal Inertia and Surface Properties for Near-Earth Asteroid (162173) 1999 JU3

In order to obtain the substantial information about the surface physics and thermal property of the target asteroid (162173) 1999 JU3, which will be visited by Hayabusa 2 in a sample return mission, with the Advanced Thermal Physical Model (ATPM) we estimate the possible thermal inertia distribution over its surface, and infer the major material composition of its surface materials. In addition, the effective diameter and geometric albedo are derived to be $D_{\rm eff}=1.13\pm0.03\rm~km$, $p_{\rm v}=0.042\pm0.003$, respectively, and the average thermal inertia is estimated to be about $(300\pm50)\rm~J\cdot m^{-2}\cdot s^{-0.5}\cdot K^{-1}$. According to the derived thermal inertia distribution, we infer that the major area on the surface of the target asteroid may be covered by loose materials, such as rock debris, sands, and so on, but few bare rocks may exist in a very small region. In this sense, the sample return mission of Hayabusa 2 is feasible, when it is performed successfully, it will certainly bring significant scientific information to the research of asteroids.

astro-ph.EP↗

arXiv2018

Tidal Evolution of Kepler lower-mass Planets

The planets with a radius $<$ 4 $R$$_\oplus$ observed by the Kepler mission exhibit a unique feature, and propose a challenge for current planetary formation models. The tidal effect between a planet and its host star plays an essential role in reconfiguring the final orbits of the short-period planets. In this work, based on various initial Rayleigh distributions of the orbital elements, the final semi-major axis distributions of the planets with a radius $<$ 4 $R_\oplus$ after suffering tidal evolutions are investigated. Our simulations have qualitatively revealed some statistical properties: the semi-major axis and its peak value all increase with the increase of the initial semi-major axis and eccentricity. For the case that the initial mean semi-major axis is less than 0.1 au and the mean eccentricity is larger than 0.25, the results of numerical simulation are approximately consistent with the observation. In addition, the effects of other parameters, such as the tidal dissipation coefficient, stellar mass and planetary mass, etc., on the final semi-major axis distribution after tidal evolution are all relatively small. Based on the simulation results, we have tried to find some clues for the formation mechanism of low-mass planets. We speculate that these low-mass planets probably form in the far place of protoplanetary disk with a moderate eccentricity via the type I migration, and it is also possible to form in situ.

astro-ph.EP↗

arXiv2018

Modeling Semantic Plausibility by Injecting World Knowledge

Distributional data tells us that a man can swallow candy, but not that a man can swallow a paintball, since this is never attested. However both are physically plausible events. This paper introduces the task of semantic plausibility: recognizing plausible but possibly novel events. We present a new crowdsourced dataset of semantic plausibility judgments of single events such as "man swallow paintball". Simple models based on distributional representations perform poorly on this task, despite doing well on selection preference, but injecting manually elicited knowledge about entity properties provides a substantial performance boost. Our error analysis shows that our new dataset is a great testbed for semantic plausibility models: more sophisticated knowledge representation and propagation could address many of the remaining errors.

cs.CL↗

arXiv2017

Width of the confinement-induced resonance in a quasi-one-dimensional trap with transverse anisotropy

We theoretically study the width of the s-wave confinement-induced resonance (CIR) in quasi-one-dimensional atomic gases under tunable transversely anisotropic confinement. We find that the width of the CIR can be tuned by varying the transverse anisotropy. The change in the width of the CIR can manifest itself in the position of the discontinuity in the interaction energy density, which can be probed experimentally.

cond-mat.quant-gas↗

arXiv2017

Distributional Modeling on a Diet: One-shot Word Learning from Text Only

We test whether distributional models can do one-shot learning of definitional properties from text only. Using Bayesian models, we find that first learning overarching structure in the known data, regularities in textual contexts and in properties, helps one-shot learning, and that individual context items can be highly informative. Our experiments show that our model can learn properties from a single exposure when given an informative utterance.

cs.CL↗

arXiv2017

Near Mean-motion Resonances in the Systems Observed by Kepler: Affected by Mass Accretion and Type I Migration

The Kepler mission has released over 4496 planetary candidates, among which 3483 planets have been confirmed as of April 2017. The statistical results of the planets show that there are two peaks around 1.5 and 2.0 in the distribution of orbital period ratios. The observations indicate that a plenty of planet pairs could have firstly been captured into mean motion resonances (MMRs) in planetary formation. Subsequently, these planets depart from exact resonant locations to be near MMRs configurations. Through type I migration, two low-mass planets have a tendency to be trapped into first-order MMRs (2:1 or 3:2 MMRs), however two scenarios of mass accretion of planets and potential outward migration play an important role in reshaping their final orbital configurations. Under the scenario of mass accretion, the planet pairs can cross 2:1 MMRs and then enter into 3:2 MMRs, especially for the inner pairs. With such formation scenario, the possibility that two planets are locked into 3:2 MMRs can increase if they are formed in a flat disk. Moreover, the outward migration can make planets have a high likelihood to be trapped into 3:2 MMRs. We perform additional runs to investigate the mass relationship for those planets in three-planet systems, and we show that two peaks near 1.5 and 2.0 for the period ratios of two planets can be easily reproduced through our formation scenario. We further show that the systems in chain resonances (e.g., 4:2:1, 3:2:1, 6:3:2 and 9:6:4 MMRs), have been observed in our simulations. This mechanism can be applicable to understand the formation of systems of Kepler-48, Kepler-53, Kepler-100, Kepler-192, Kepler-297, Kepler-399, and Kepler-450.

astro-ph.EP↗

arXiv2017

Leveraging Discourse Information Effectively for Authorship Attribution

We explore techniques to maximize the effectiveness of discourse information in the task of authorship attribution. We present a novel method to embed discourse features in a Convolutional Neural Network text classifier, which achieves a state-of-the-art result by a substantial margin. We empirically investigate several featurization methods to understand the conditions under which discourse features contribute non-trivial performance gains, and analyze discourse embeddings.

cs.CL↗

arXiv2017

Topological Fulde-Ferrell states in alkaline-earth-metal-like atoms near an orbital Feshbach resonance

We study the effects of synthetic spin-orbit coupling on the pairing physics in quasi-one-dimensional ultracold Fermi gases of alkaline-earth-metal-like atoms near an orbital Feshbach resonance (OFR). The interplay between spin-orbit coupling and pairing interactions near the OFR leads to an interesting topological Fulde-Ferrell state, where the nontrivial topology of the state is solely encoded in the closed channel with a topologically trivial Fulde-Ferrell pairing in the open channel. We confirm the topological property of the system by characterizing the Zak phase and the edge states. The topological Fulde-Ferrell state can be identified by the momentum-space density distribution obtained from time-of-flight images.

cond-mat.quant-gas↗

arXiv2017

Dynamically manipulating topological physics and edge modes in a single degenerate optical cavity

We propose a scheme to simulate topological physics within a single degenerate cavity, whose modes are mapped to lattice sites. A crucial ingredient of the scheme is to construct a sharp boundary so that the open boundary condition can be implemented for this effective lattice system. In doing so, the topological properties of the system can manifest themselves on the edge states, which can be probed from the spectrum of an output cavity field. We demonstrate this with two examples: a static Su-Schrieffer-Heeger chain and a periodically driven Floquet topological insulator. Our work opens up new avenues to explore exotic photonic topological phases inside a single optical cavity.

quant-ph↗

arXiv2017

Terrestrial Planets Formation under Migration: the Systems near 4:2:1 Mean Motion Resonance

In this work, we extensively investigate the formation of near 4:2:1 mean motion resonances (MMRs) configuration by performing two sets of N-body simulations. We model the eccentricity damping, gas drag, type I and type II planetary migration of planetesimals, planetary embryos and giant planets in the first sets. For the simulations of giant planets with type II migration, the massive terrestrial planets, with a mass up to several Earth masses, are likely produced in the systems. We further show that by shepherding and/or scattering mechanisms through Jovian planet's type II migration, the terrestrial planets and giant planets in the systems can be evolved into a near 4:2:1 MMRs. Moreover, the models are applicable to the formation of Kepler-238 and 302 systems. In the second set, we study the 4:2:1 MMRs formation in the terrestrial planetary systems, where the planets undergo type I migration and eccentricity damping. By considering type I migration, $\sim$ 17.1\% of the simulations indicate that terrestrial planets are evolved into 4:2:1 MMRs. However, this probability should depend on the initial conditions of planets. Hence, we conclude that both type I and type II migration can play a crucial role in close-in terrestrial planet formation.

astro-ph.EP↗

arXiv2015

Chang'e-2 spacecraft observations of asteroid 4179 Toutatis

On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root of a smaller lobe (head) and a larger lobe (body). Such bilobate shape is indicative of a contact binary origin for Toutatis. In addition, the high-resolution images better than 3 meters provide a number of new discoveries about this asteroid, such as an 800-meter depression at the end of the large lobe, a sharply perpendicular silhouette near the neck region, boulders, indicating that Toutatis is probably a rubble-pile asteroid. Chang'e-2 observations have significantly revealed new insights into the geological features and the formation and evolution of this asteroid. In final, we brief the future Chinese asteroid mission concept.

astro-ph.EP↗

arXiv2014

Near 3:2 and 2:1 mean motion resonances formation in the systems observed by Kepler

The Kepler mission has released ~4229 transiting planet candidates. There are approximately 222 candidate systems with three planets. Among them, the period ratios of planet pairs near 1.5 and 2.0 reveal that two peaks exist for which the proportions of the candidate systems are ~7.0% and 18.0%, respectively. In this work, we study the formation of mean motion resonance (MMR) systems, particularly for the planetary configurations near 3:2 and 2:1 MMRs, and we concentrate on the interplay between the resonant configuration and the combination of stellar accretion rate, stellar magnetic field, speed of migration and additional planets. We perform more than 1000 runs by assuming a system with a solar-like star and three surrounding planets. From the statistical results, we find that under the formation scenario, the proportions near 1.5 and 2.0 can reach 14.5% and 26.0%, respectively. In addition, $\dot M=0.1\times 10^{-8} ~M_\odot ~{\rm yr^{-1}}$ is propitious toward the formation of 3:2 resonance, whereas $\dot M=2\times 10^{-8} ~M_\odot ~{\rm yr^{-1}}$ contributes to the formation of 2:1 resonance. The speed-reduction factor of type I migration $f_1\geq 0.3$ facilitates 3:2 MMRs, whereas $f_1\geq 0.1$ facilitates 2:1 MMRs. If additional planets are present in orbits within the innermost or beyond the outermost planet in a three-planet system, 3:2:1 MMRs can be formed, but the original systems trapped in 4:2:1 MMRs are not affected by the supposed planets. In summary, we conclude that this formation scenario will provide a likely explanation for Kepler candidates involved in 2:1 and 3:2 MMRs.

astro-ph.EP↗

arXiv2014

Shape, Thermal and Surface Properties determination of a Candidate Spacecraft Target Asteroid (175706) 1996 FG3

In this paper, a 3D convex shape model of (175706) 1996 FG3, which consists of 2040 triangle facets and 1022 vertices, is derived from the known lightcurves. The best-fit orientation of the asteroid's spin axis is determined to be $λ=237.7^\circ$ and $β=-83.8^{\circ}$ considering the observation uncertainties, and its rotation period is $\sim$ 3.5935 h . Using the derived shape model, we adopt the so-called advanced thermophysical model (ATPM) to fit three published sets of mid-infrared observations of 1996 FG3 \citep{Wolters2011,Walsh2012}, so as to evaluate its surface properties. Assuming the primary and the secondary bear identical shape, albedo, thermal inertia and surface roughness, the best-fit parameters are obtained from the observations. The geometric albedo and effective diameter of the asteroid are reckoned to be $p_{\rm v}=0.045\pm0.002$, $D_{\rm eff}=1.69^{+0.05}_{-0.02}$ km. The diameters of the primary and secondary are determined to be $D_{1}=1.63^{+0.04}_{-0.03}$ km and $D_{2}=0.45^{+0.04}_{-0.03}$ km, respectively. The surface thermal inertia $Γ$ is derived to be a low value of $80\pm40\rm Jm^{-2}s^{-0.5}K^{-1}$ with a roughness fraction $f_{\rm R}$ of $0.8^{+0.2}_{-0.4}$. This indicates that the primary possibly has a regolith layer on its surface, which is likely to be covered by a mixture of dust, fragmentary rocky debris and sand. The minimum regolith depth is estimated to be $5\sim20\rm mm$ from the simulations of subsurface temperature distribution, indicating that 1996 FG3 could be a very suitable target for a sample return mission.

astro-ph.EP↗

arXiv2013

The Ginger-shaped Asteroid 4179 Toutatis: New Observations from a Successful Flyby of Chang'e-2

On 13 December 2012, Chang'e-2 conducted a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 $\pm$ 120 meters from the asteroid's surface. The highest-resolution image, with a resolution of better than 3 meters, reveals new discoveries on the asteroid, e.g., a giant basin at the big end, a sharply perpendicular silhouette near the neck region, and direct evidence of boulders and regolith, which suggests that Toutatis may bear a rubble-pile structure. Toutatis' maximum physical length and width are (4.75 $\times$ 1.95 km) $\pm$10$\%$, respectively, and the direction of the +$z$ axis is estimated to be (250$\pm$5$^\circ$, 63$\pm$5$^\circ$) with respect to the J2000 ecliptic coordinate system. The bifurcated configuration is indicative of a contact binary origin for Toutatis, which is composed of two lobes (head and body). Chang'e-2 observations have significantly improved our understanding of the characteristics, formation, and evolution of asteroids in general.

astro-ph.EP↗

arXiv2012

Predicting the Configuration of Planetary System: KOI-152 Observed by Kepler

The recent Kepler discovery of KOI-152 reveals a system of three hot super-Earth candidates that are in or near a 4:2:1 mean motion resonance. It is unlikely that they formed in situ, the planets probably underwent orbital migration during the formation and evolution process. The small semimajor axes of the three planets suggest that migration stopped at the inner edge of the primordial gas disk. In this paper we focus on the influence of migration halting mechanisms, including migration "dead zones", and inner truncation by the stellar magnetic field. We show that the stellar accretion rate, stellar magnetic field and the speed of migration in the proto-planetary disk are the main factors affecting the final configuration of KOI-152. Our simulations suggest that three planets may be around a star with low star accretion rate or with high magnetic field. On the other hand, slow type I migration, which decreases to one tenth of the linear analysis results, favors forming the configuration of KOI-152. Under such formation scenario, the planets in the system are not massive enough to open gaps in the gas disk. The upper limit of the planetary masses are estimated to be about $15,~19$, and $24 M_\oplus$, respectively. Our results are also indicative of the near Laplacian configurations that are quite common in planetary systems.

astro-ph.EP↗