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Haiyang Liu

Publications and source records attributed to Haiyang Liu.

52 records · Page 3Linked to original sources

Attention-based Spatial-Temporal Graph Convolutional Recurrent Networks for Traffic Forecasting

Traffic forecasting is one of the most fundamental problems in transportation science and artificial intelligence. The key challenge is to effectively model complex spatial-temporal dependencies and correlations in modern traffic data. Existing methods, however, cannot accurately model both long-term and short-term temporal correlations simultaneously, limiting their expressive power on complex spatial-temporal patterns. In this paper, we propose a novel spatial-temporal neural network framework: Attention-based Spatial-Temporal Graph Convolutional Recurrent Network (ASTGCRN), which consists of a graph convolutional recurrent module (GCRN) and a global attention module. In particular, GCRN integrates gated recurrent units and adaptive graph convolutional networks for dynamically learning graph structures and capturing spatial dependencies and local temporal relationships. To effectively extract global temporal dependencies, we design a temporal attention layer and implement it as three independent modules based on multi-head self-attention, transformer, and informer respectively. Extensive experiments on five real traffic datasets have demonstrated the excellent predictive performance of all our three models with all their average MAE, RMSE and MAPE across the test datasets lower than the baseline methods.

cs.LG↗

Visual Attention-based Self-supervised Absolute Depth Estimation using Geometric Priors in Autonomous Driving

Although existing monocular depth estimation methods have made great progress, predicting an accurate absolute depth map from a single image is still challenging due to the limited modeling capacity of networks and the scale ambiguity issue. In this paper, we introduce a fully Visual Attention-based Depth (VADepth) network, where spatial attention and channel attention are applied to all stages. By continuously extracting the dependencies of features along the spatial and channel dimensions over a long distance, VADepth network can effectively preserve important details and suppress interfering features to better perceive the scene structure for more accurate depth estimates. In addition, we utilize geometric priors to form scale constraints for scale-aware model training. Specifically, we construct a novel scale-aware loss using the distance between the camera and a plane fitted by the ground points corresponding to the pixels of the rectangular area in the bottom middle of the image. Experimental results on the KITTI dataset show that this architecture achieves the state-of-the-art performance and our method can directly output absolute depth without post-processing. Moreover, our experiments on the SeasonDepth dataset also demonstrate the robustness of our model to multiple unseen environments.

cs.CV↗

BEAT: A Large-Scale Semantic and Emotional Multi-Modal Dataset for Conversational Gestures Synthesis

Achieving realistic, vivid, and human-like synthesized conversational gestures conditioned on multi-modal data is still an unsolved problem due to the lack of available datasets, models and standard evaluation metrics. To address this, we build Body-Expression-Audio-Text dataset, BEAT, which has i) 76 hours, high-quality, multi-modal data captured from 30 speakers talking with eight different emotions and in four different languages, ii) 32 millions frame-level emotion and semantic relevance annotations. Our statistical analysis on BEAT demonstrates the correlation of conversational gestures with facial expressions, emotions, and semantics, in addition to the known correlation with audio, text, and speaker identity. Based on this observation, we propose a baseline model, Cascaded Motion Network (CaMN), which consists of above six modalities modeled in a cascaded architecture for gesture synthesis. To evaluate the semantic relevancy, we introduce a metric, Semantic Relevance Gesture Recall (SRGR). Qualitative and quantitative experiments demonstrate metrics' validness, ground truth data quality, and baseline's state-of-the-art performance. To the best of our knowledge, BEAT is the largest motion capture dataset for investigating human gestures, which may contribute to a number of different research fields, including controllable gesture synthesis, cross-modality analysis, and emotional gesture recognition. The data, code and model are available on https://pantomatrix.github.io/BEAT/.

cs.CV↗

Spatially resolved mass-metallicity relation at z~0.26 from the MUSE-Wide Survey

Aims: There is a spatially resolved star-forming main sequence (rSFMS) and mass-metallicity relation (rMZR) of galaxies in local universe. We know that the global mass-metallicity relation (MZR) results from the integral of rMZR, and it will evolve with the redshift. However, the evolution of rMZR with redshift is still unclear due to the low spatial resolution and signal-to-noise ratio. There are currently too few observations beyond local universe, and only simulations can reproduce the evolution of rMZR with redshift. Methods: In this work, we select ten emission-line galaxies with an average redshift of $z\sim 0.26$ from MUSE-Wide DR1. We obtain the spatially resolved star formation rate (SFR) and metallicity from the integral field spectroscopy (IFS), as well as the stellar mass surface density from the 3D-HST photometry. We derive the rSFMS and rMZR at $z\sim 0.26$ and compare them with local galaxies. Results: We find the rSFMS of galaxies at $z\sim 0.26$ has a slope of $\sim$0.771. The rMZR exists at $z\sim 0.26$, showing a similar shape to the local universe but a lower average metallicity about $\sim$0.11 dex than the local one. In addition, we also study their spatially resolved fundamental metallicity relation (rFMR). However, there is no obvious evidence that rFMR exists at $z\sim$0.26 and it is not an extension of rMZR at a high SFR. Conclusions: Similar to their global versions, the rSFMS and rMZR of galaxies also evolve with redshift. Given the fixed stellar mass, galaxies at higher redshift show higher SFR and lower metallicity. These suggest that the evolution of the global galaxy properties with redshift may result from integrating the evolution of spatially resolved properties of galaxies.

astro-ph.GA↗

Sub-galactic scaling relations with T$_{\rm e}$-based metallicity of low metallicity regions in galaxies: metal-poor gas inflow may have important effects?

The scaling relationship is a fundamental probe of the evolution of galaxies. Using the integral field spectroscopic data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we select 1698 spaxels with significant detection of the auroral emission line \oiii$λ$4363 from 52 galaxies to investigate the scaling relationships at the low-metallicity end. We find that our sample's star formation rate is higher and its metallicity is lower in the scaling relationship than the star-forming sequence after removing the contribution of the Fundamental Metallicity Relation.We also find that the stellar ages of our sample are younger ($<$ 1 Gyr) and the stellar metallicities are also lower. Morphological parameters from Deep Learning catalog indicate that our galaxies are more likely to be merger. These results suggest that their low metallicity regions may be related to interaction, the inflow of metal-poor gas may dilute the interstellar medium and form new metal-poor stars in these galaxies during interaction.

astro-ph.GA↗

Self-Supervision and Spatial-Sequential Attention Based Loss for Multi-Person Pose Estimation

Bottom-up based multi-person pose estimation approaches use heatmaps with auxiliary predictions to estimate joint positions and belonging at one time. Recently, various combinations between auxiliary predictions and heatmaps have been proposed for higher performance, these predictions are supervised by the corresponding L2 loss function directly. However, the lack of more explicit supervision results in low features utilization and contradictions between predictions in one model. To solve these problems, this paper proposes (i) a new loss organization method which uses self-supervised heatmaps to reduce prediction contradictions and spatial-sequential attention to enhance networks' features extraction; (ii) a new combination of predictions composed by heatmaps, Part Affinity Fields (PAFs) and our block-inside offsets to fix pixel-level joints positions and further demonstrates the effectiveness of proposed loss function. Experiments are conducted on the MS COCO keypoint dataset and adopting OpenPose as the baseline model. Our method outperforms the baseline overall. On the COCO verification dataset, the mAP of OpenPose trained with our proposals outperforms the OpenPose baseline by over 5.5%.

cs.CV↗

Improving Ultrasound Tongue Image Reconstruction from Lip Images Using Self-supervised Learning and Attention Mechanism

Speech production is a dynamic procedure, which involved multi human organs including the tongue, jaw and lips. Modeling the dynamics of the vocal tract deformation is a fundamental problem to understand the speech, which is the most common way for human daily communication. Researchers employ several sensory streams to describe the process simultaneously, which are incontrovertibly statistically related to other streams. In this paper, we address the following question: given an observable image sequences of lips, can we picture the corresponding tongue motion. We formulated this problem as the self-supervised learning problem, and employ the two-stream convolutional network and long-short memory network for the learning task, with the attention mechanism. We evaluate the performance of the proposed method by leveraging the unlabeled lip videos to predict an upcoming ultrasound tongue image sequence. The results show that our model is able to generate images that close to the real ultrasound tongue images, and results in the matching between two imaging modalities.

eess.AS↗

Privacy-Preserving Cloud-Aided Broad Learning System

With the rapid development of artificial intelligence and the advent of the 5G era, deep learning has received extensive attention from researchers. Broad Learning System (BLS) is a new deep learning model proposed recently, which shows its effectiveness in many fields, such as image recognition and fault detection. However, the training process still requires vast computations, and therefore cannot be accomplished by some resource-constrained devices. To solve this problem, the resource-constrained device can outsource the BLS algorithm to cloud servers. Nevertheless, some security challenges also follow with the use of cloud computing, including the privacy of the data and the correctness of returned results. In this paper, we propose a secure, efficient, and verifiable outsourcing algorithm for BLS. This algorithm not only improves the efficiency of the algorithm on the client but also ensures that the clients sensitive information is not leaked to the cloud server. In addition, in our algorithm, the client can verify the correctness of returned results with a probability of almost 1. Finally, we analyze the security and efficiency of our algorithm in theory and prove our algorithms feasibility through experiments.

cs.CR↗

Dust Attenuation Curve for Local Subgalactic Star-forming Regions

We compile a sample of about 157,000 spaxels from the Mapping Nearby Galaxies at the Apache Point Observatory survey to derive the average dust attenuation curve for subgalactic star-forming regions of local star-forming galaxies (SFGs) in the optical wavelength, following the method of \cite{Calzetti1994}. We obtain a $D_n(4000)$-independent average attenuation curve for spaxels with $1.1\leq D_n(4000)<1.3$, which is similar to the one derived from either local starbursts or normal SFGs. We examine whether and how the shape of the average attenuation curve changes with several local and global physical properties. For spaxels with $1.2\leq D_n(4000)<1.3$, we find no dependence on either local or global physical properties for the shape of the average attenuation curve. However, for spaxels with younger stellar population ($1.1\leq D_n(4000)<1.2$), shallower average attenuation curves are found for star-forming regions with smaller stellar mass surface density, smaller star formation rate surface density, or those residing in the outer region of galaxies. These results emphasize the risk of using one single attenuation curve to correct the dust reddening for all types of star-forming regions, especially for those with fairly young stellar population.

astro-ph.GA↗

Towards User Friendly Medication Mapping Using Entity-Boosted Two-Tower Neural Network

Recent advancements in medical entity linking have been applied in the area of scientific literature and social media data. However, with the adoption of telemedicine and conversational agents such as Alexa in healthcare settings, medical name inference has become an important task. Medication name inference is the task of mapping user friendly medication names from a free-form text to a concept in a normalized medication list. This is challenging due to the differences in the use of medical terminology from health care professionals and user conversations coming from the lay public. We begin with mapping descriptive medication phrases (DMP) to standard medication names (SMN). Given the prescriptions of each patient, we want to provide them with the flexibility of referring to the medication in their preferred ways. We approach this as a ranking problem which maps SMN to DMP by ordering the list of medications in the patient's prescription list obtained from pharmacies. Furthermore, we leveraged the output of intermediate layers and performed medication clustering. We present the Medication Inference Model (MIM) achieving state-of-the-art results. By incorporating medical entities based attention, we have obtained further improvement for ranking models.

cs.CL↗

New Constraints on the Origin of Surface Brightness Profile Breaks of Disk Galaxies from MaNGA

In an effort to probe the origin of surface brightness profile (SBP) breaks widely observed in nearby disk galaxies, we carry out a comparative study of stellar population profiles of 635 disk galaxies selected from the MaNGA spectroscopic survey. We classify our galaxies into single exponential (TI), down-bending (TII) and up-bending (TIII) SBP types, and derive their spin parameters and radial profiles of age/metallicity-sensitive spectral features. Most TII (TIII) galaxies have down-bending (up-bending) star formation rate (SFR) radial profiles, implying that abrupt radial changes of SFR intensities contribute to the formation of both TII and TIII breaks. Nevertheless, a comparison between our galaxies and simulations suggests that stellar migration plays a significant role in weakening down-bending $Σ_{\star}$ profile breaks. While there is a correlation between the break strengths of SBPs and age/metallicity-sensitive spectral features for TII galaxies, no such correlation is found for TIII galaxies, indicating that stellar migration may not play a major role in shaping TIII breaks, as is evidenced by a good correspondence between break strengths of $Σ_{\star}$ and surface brightness profiles of TIII galaxies. We do not find evidence for galaxy spin being a relevant parameter for forming different SBP types, nor do we find significant differences between the asymmetries of galaxies with different SBP types, suggesting that environmental disturbances or satellite accretion in the recent past do not significantly influence the break formation. By dividing our sample into early and late morphological types, we find that galaxies with different SBP types follow nearly the same tight stellar mass-$R_{25}$ relation, which makes the hypothesis that stellar migration alone can transform SBP types from TII to TI and then to TIII highly unlikely.

astro-ph.GA↗

Learning unbiased zero-shot semantic segmentation networks via transductive transfer

Semantic segmentation, which aims to acquire a detailed understanding of images, is an essential issue in computer vision. However, in practical scenarios, new categories that are different from the categories in training usually appear. Since it is impractical to collect labeled data for all categories, how to conduct zero-shot learning in semantic segmentation establishes an important problem. Although the attribute embedding of categories can promote effective knowledge transfer across different categories, the prediction of segmentation network reveals obvious bias to seen categories. In this paper, we propose an easy-to-implement transductive approach to alleviate the prediction bias in zero-shot semantic segmentation. Our method assumes that both the source images with full pixel-level labels and unlabeled target images are available during training. To be specific, the source images are used to learn the relationship between visual images and semantic embeddings, while the target images are used to alleviate the prediction bias towards seen categories. We conduct comprehensive experiments on diverse split s of the PASCAL dataset. The experimental results clearly demonstrate the effectiveness of our method.

cs.CV↗

Random Pairwise Shapelets Forest

Shapelet is a discriminative subsequence of time series. An advanced shapelet-based method is to embed shapelet into accurate and fast random forest. However, it shows several limitations. First, random shapelet forest requires a large training cost for split threshold searching. Second, a single shapelet provides limited information for only one branch of the decision tree, resulting in insufficient accuracy and interpretability. Third, randomized ensemble causes interpretability declining. For that, this paper presents Random Pairwise Shapelets Forest (RPSF). RPSF combines a pair of shapelets from different classes to construct random forest. It omits threshold searching to be more efficient, includes more information for each node of the forest to be more effective. Moreover, a discriminability metric, Decomposed Mean Decrease Impurity (DMDI), is proposed to identify influential region for every class. Extensive experiments show RPSF improves the accuracy and training speed of shapelet-based forest. Case studies demonstrate the interpretability of our method.

cs.LG↗

What determines the local metallicity of galaxies: global stellar mass, local stellar mass surface density or star formation rate?

The metallicity and its relationship with other galactic properties is a fundamental probe of the evolution of galaxies. In this work, we select about 750,000 star-forming spatial pixels from 1122 blue galaxies in the MaNGA survey to investigate the global stellar mass - local stellar mass surface density - gas-phase metallicity ($M_*$ - $Σ_*$ - $Z$ ) relation. At a fixed $M_*$, the metallicity increases steeply with increasing $Σ_*$. Similarly, at a fixed $Σ_*$, the metallicity increases strongly with increasing $M_*$ at low mass end, while this trend becomes less obvious at high mass end. We find the metallicity to be more strongly correlated to $Σ_*$ than to $M_*$. Furthermore, we construct a tight (0.07 dex scatter) $M_*$ - $Σ_*$ - $Z$ relation, which reduces the scatter in the $Σ_*$ - $Z$ relation by about 30$\%$ for galaxies with $7.8 < {\rm log}(M_*/M_\odot) < 11.0$, while the reduction of scatter is much weaker for high-mass galaxies. This result suggests that, especially for low-mass galaxies, the $M_*$ - $Σ_*$ - $Z$ relation is largely more fundamental than the $M_*$ - $Z$ and $Σ_*$ - $Z$ relations, meaning that both $M_*$ and $Σ_*$ play important roles in shaping the local metallicity. We also find that the local metallicity is probably independent on the local star formation rate surface density at a fixed $M_*$ and $Σ_*$. Our results are consistent with the scenario that the local metallicities in galaxies are shaped by the combination of the local stars formed in the history and the metal loss caused by galactic winds.

astro-ph.GA↗

Elevation or Suppression? The Resolved Star Formation Main Sequence of Galaxies with Two Different Assembly Modes

We investigate the spatially-resolved star formation main sequence in star-forming galaxies (SFGs) using Integral Field Spectroscopic (IFS) observations from the Mapping Nearby Galaxies at the Apache Point Observatory (MaNGA) survey. We demonstrate that the correlation between the stellar mass surface density ($Σ_*$) and star formation rate surface density ($Σ_{\mathrm{SFR}}$) holds down to sub-galactic scale, leading to the Sub-Galactic Main Sequence (SGMS). By dividing galaxies into two populations based on their recent mass assembly modes, we find the resolved main sequence in galaxies with 'outside-in' mode is steeper than that in galaxies with 'inside-out' mode. This is also confirmed on a galaxy-by-galaxy level, where we find the distributions of SGMS slopes for individual galaxies are clearly separated for the two populations. When normalizing and stacking the SGMS of individual galaxies on one panel for the two populations, we find the inner regions of galaxies with 'inside-out' mode statistically exhibit a suppression in star formation, with a less significant trend in the outer regions of galaxies with 'outside-in' mode. In contrast, the inner regions of galaxies with 'outside-in' mode and the outer regions of galaxies with 'inside-out' mode follow a slightly sub-linear scaling relation with a slope $\sim$0.9, which is in good agreement with previous findings, suggesting that they are experiencing a universal regulation without influences of additional physical processes.

astro-ph.GA↗

A sample of metal-poor galaxies identified from the LAMOST spectral survey

We present a sample of 48 metal-poor galaxies at $ z < 0.14$ selected from 92,510 galaxies in the LAMOST survey. These galaxies are identified for their detection of the auroral emission line \oiii$λ$4363 above $3σ$ level, which allows a direct measurement of the electron temperature and the oxygen abundance. The emission line fluxes are corrected for internal dust extinction using Balmer decrement method. With electron temperature derived from \oiii$λ\lambda4959,5007/\oiii\lambda4363$ and electron density from $\sii\lambda6731/\sii\lambda6717$, we obtain the oxygen abundances in our sample which range from $\zoh= 7.63$ (0.09 $\Zsun$) to $8.46$ (0.6 $\Zsun$). We find an extremely metal-poor galaxy with $\zoh=7.63 \pm 0.01$. With multiband photometric data from FUV to NIR and $\ha$ measurements, we also determine the stellar masses and star formation rates, based on the spectral energy distribution fitting and $\ha$ luminosity, respectively. We find that our galaxies have low and intermediate stellar masses with $\rm 6.39 \le log(M/M_{\sun})\le 9.27$, and high star formation rates (SFRs) with $\rm -2.18 \le log(SFR/M_{\sun} yr^{-1}) \le 1.95$. We also find that the metallicities of our galaxies are consistent with the local $T_e$-based mass-metallicity relation, while the scatter is about 0.28 dex. Additionally, assuming the coefficient of $\rm α=0.66$, we find most of our galaxies follow the local mass-metallicity-SFR relation, while a scatter about 0.24 dex exists, suggesting the mass-metallicity relation is weakly dependent on SFR for those metal-poor galaxies.

astro-ph.GA↗