arXiv subjects

Hong Wu

Publications and source records attributed to Hong Wu.

At least 55 records · Page 3Linked to original sources

arXiv2025

Photometric-Metallicity and Distance Estimates for $\sim$70,000 RR Lyrae Stars from the Zwicky Transient Facility

Utilizing Zwicky Transient Facility (ZTF) data and existing RR Lyrae stars (RRLs) catalogs, this study achieves the first calibration of the $P - ϕ_{31} - R_{21} - \text{[Fe/H]}$ and $P-ϕ_{31}-A_{2}-A_{1}-\text{[Fe/H]}$ relations in the ZTF photometric system for RRab and RRc stars. We also re-calibrate the period-absolute magnitude-metallicity (PMZ) and period-Wesenheit-metallicity (PWZ) relations in the ZTF $gri$-bands for RRab and RRc stars. Based on nearly 4100 stars with precise measurements of $P$, $ϕ_{31}$, $A_{2}$, and $A_{1}$, and available spectroscopic-metallicity estimates, the photometric-metallicity relations exhibit strong internal consistency across different bands, supporting the use of a weighted averaging method for the final estimates. The photometric-metallicity estimates of globular clusters based on RR Lyrae members also show excellent agreement with high-resolution spectroscopic measurements, with typical scatter of 0.15 dex for RRab stars and 0.14 dex for RRc stars, respectively. Using hundreds of local RRLs with newly derived photometric metallicities and precise Gaia Data Release 3 parallaxes, we establish the PMZ and PWZ relations in multiple bands. Validation with globular cluster RR Lyrae members reveals typical distance errors of 3.1% and 3.0% for the PMZ relations, and 3.1% and 2.6% for the PWZ relations for RRab and RRc stars, respectively. Compared to PMZ relations, the PWZ relations are tighter and almost unbiased, making them the recommended choice for distance calculations. We present a catalog of 73,795 RRLs with precise photometric metallicities; over 95% of them have accurate distance measurements. Compared to Gaia DR3, approximately 25,000 RRLs have precise photometric metallicities and distances derived for the first time.

astro-ph.SR↗

arXiv2025

"Frog-eyes" in Astronomy: Monitoring Binary Radial Velocity Variations Through A Pair of Narrow-Band Filters

Spectroscopic observations are a crucial step in driving major discoveries in the era of time-domain surveys. However, the pace of current spectroscopic surveys is increasingly unable to meet the demands of rapidly advancing large-scale time-domain surveys. To address this issue, we propose the ``Frog-eyes" system, which employs a pair of narrow-band filters: one positioned near a strong absorption line to capture signals from Doppler shifts, and the other placed on the adjacent continuum to monitor intrinsic variations. The combination of observations from the two filters enables the extraction of radial velocity (RV) curves from a large sample of binary stars, and is particularly efficient for single-lined binaries (SB1), using photometric techniques. Comprehensive mock simulations on SB1 demonstrate that the binary orbital parameters can be precisely measured from the extracted RV curves for binary systems where the primary star has an effective temperature greater than 6000 K. With a typical ground-based photometric precision of approximately 0.3%, the uncertainties in the derived semi-amplitude K and eccentricity e are less than 10% and 0.1, respectively, for binary systems with K $\ge$ 30 km/s. These encouraging results are further validated by real observations of the hot subdwarf-white dwarf binary system HD 265435, using a non-specialized ``Frog-eyes" system installed on the Chinese 2.16m telescope. Once this system is properly installed on large-field-of-view survey telescopes, the rate of acquiring RV curves for binaries will approach their detection rate in leading time-domain photometric surveys.

astro-ph.SR↗

arXiv2025

The Gas-to-Dust Ratio Investigation in the Massive Star-Forming region M17

M17 is a well-known massive star-forming region, and its Gas-to-Dust Ratio (GDR) may vary significantly compared to the other areas. The mass of gas can be traced by the ${\rm CO}$ emission observed in the \emph{Milky Way Imaging Scroll Painting (MWISP) project}. The dust mass can be traced by analyzing the interstellar extinction magnitude obtained from the \emph{United Kingdom Infrared Telescope (UKIRT)}. We computed the ratio ${W({\rm CO})/A_V}$: for ${A_V \le }$ 10 mag, ${{ W(^{12}{\rm CO})/ A_V}= (6.27 \pm 0.19)}$ ${\mathrm{{K \cdot km/s} \cdot mag^{-1}}}$ and ${{ W(^{13}{\rm CO})/ A_V} = (0.75 \pm 0.72)}$ ${ \mathrm{{K \cdot km/s} \cdot mag^{-1}}}$; whereas for ${{A_V} \ge 10}$ mag, ${{ W(^{12}{\rm CO})/ A_V} = (15.8 \pm 0.06) }$ ${\mathrm{{K \cdot km/s} \cdot mag^{-1}}}$ and ${{ W(^{13}{\rm CO})/ A_V} = (3.11 \pm 0.25)}$ ${ \mathrm{{K \cdot km/s} \cdot mag^{-1}}}$. Then, we converted the ${W({\rm CO})/A_V}$ into ${N(\rm H)/A_V}$. Using the WD01 model, we derived the GDR: for ${A_V \le }$ 10 mag, the GDRs were ${118 \pm 9}$ for ${^{12}{\rm CO}}$ and ${83 \pm 62}$ for ${^{13}{\rm CO}}$, comparable to those of the Milky Way; however, for ${A_V \ge }$ 10 mag, the GDRs increased significantly to ${296 \pm 3}$ for ${^{12}{\rm CO}}$ and ${387 \pm 40}$ for ${^{13}{\rm CO}}$, approximately three times higher than those of the Milky Way. In the discussion, we compared the results of this work with previous studies and provided a detailed discussion of the influence of massive stars and other factors on GDR.

astro-ph.GA↗

arXiv2025

Cross-Modal Synergies: Unveiling the Potential of Motion-Aware Fusion Networks in Handling Dynamic and Static ReID Scenarios

Navigating the complexities of person re-identification (ReID) in varied surveillance scenarios, particularly when occlusions occur, poses significant challenges. We introduce an innovative Motion-Aware Fusion (MOTAR-FUSE) network that utilizes motion cues derived from static imagery to significantly enhance ReID capabilities. This network incorporates a dual-input visual adapter capable of processing both images and videos, thereby facilitating more effective feature extraction. A unique aspect of our approach is the integration of a motion consistency task, which empowers the motion-aware transformer to adeptly capture the dynamics of human motion. This technique substantially improves the recognition of features in scenarios where occlusions are prevalent, thereby advancing the ReID process. Our comprehensive evaluations across multiple ReID benchmarks, including holistic, occluded, and video-based scenarios, demonstrate that our MOTAR-FUSE network achieves superior performance compared to existing approaches.

cs.CV↗

arXiv2024

Diffuse Ionized Gas in the Anti-center of the Milky Way

Using data from the LAMOST Medium-Resolution Spectroscopic Survey of Nebulae, we create a sample of 17,821 diffuse ionized gas (DIG) spectra in the anti-center region of the Milky Way, by excluding fibers in the directions of H II regions and supernova remnants. We then analyze the radial and vertical distributions of three line ratios ([N II]/H$α$, [S II]/H$α$, and [S II]/[N II]), as well as the oxygen abundance. [N II]/H$α$ and [S II]/H$α$ do not exhibit a consistent, monotonic decrease with increasing Galactocentric distance (R$_{gal}$). Instead, they show enhancement within the interarm region, positioned between the Local Arm and the Perseus Arm. [S II]/[N II] has a radial gradient of 0.1415 $\pm$ 0.0646 kpc$^{-1}$ for the inner disk (8.34 $ < R_{gal} < $ 9.65 kpc), and remains nearly flat for the outer disk ($R_{gal} > $ 9.65 kpc). In the vertical direction, [N II]/H$α$, [S II]/H$α$, and [S II]/[N II] increase with increasing Galactic disk height ($|z|$) in both southern and northern disks. Based on the N2S2H$α$ method, which combines [S II]/[N II] and [N II]/H$α$, we estimate the oxygen abundance. The oxygen abundance exhibits a consistent radial gradient with R$_{gal}$, featuring a slope of -0.0559 $\pm$ 0.0209 dex kpc$^{-1}$ for the inner disk and a similar slope of -0.0429 $\pm$ 0.0599 dex kpc$^{-1}$ for the outer disk. A single linear fitting to the entire disk yields a slope of -0.0317 $\pm$ 0.0124 dex kpc$^{-1}$. In the vertical direction, the oxygen abundance decreases with increasing $|z|$ in both southern and northern disks.

astro-ph.GA↗

arXiv2024

A Narrative Review of Image Processing Techniques Related to Prostate Ultrasound

Prostate cancer (PCa) poses a significant threat to men's health, with early diagnosis being crucial for improving prognosis and reducing mortality rates. Transrectal ultrasound (TRUS) plays a vital role in the diagnosis and image-guided intervention of PCa.To facilitate physicians with more accurate and efficient computer-assisted diagnosis and interventions, many image processing algorithms in TRUS have been proposed and achieved state-of-the-art performance in several tasks, including prostate gland segmentation, prostate image registration, PCa classification and detection, and interventional needle detection. The rapid development of these algorithms over the past two decades necessitates a comprehensive summary. In consequence, this survey provides a \textcolor{blue}{narrative } analysis of this field, outlining the evolution of image processing methods in the context of TRUS image analysis and meanwhile highlighting their relevant contributions. Furthermore, this survey discusses current challenges and suggests future research directions to possibly advance this field further.

eess.IV↗

arXiv2024

Ionized and cold gas components in low surface brightness galaxy AGC 102004

We present the integral field spectroscopic observations of ionized gas (H$α$ and [{\ion{N}{II}}]) using the PCWI, along with deep CO(2-1) observations by the $^\backprime\bar{\rm U}^\backprime\bar{\rm u}$ receiver on JCMT for AGC 102004. The velocity field of H$α$ shows an anomalous distribution in the North-Western (NW) disk. The H$α$ spectrum is well-fitted by two Gaussian components, and the weak Gaussian component is dominated by the anomalous H$α$ in the NW disk. The Gaussian fit center of H$α$ emission is offset by +24.2 km s$^{-1}$ from the systemic velocity obtained from the HI emission. We derive the gas-phase metallicity, 12+log(O/H), using [{\ion{N}{II}}]$λ$6583/H$α$ ratio as a proxy. The mean value of 12+log(O/H) is 8.30 $\pm$ 0.19 over the whole galaxy. The metallicity in the outer disk is lower than the detection limit of 7.72, indicating the metallicity gradient exists in AGC 102004. We speculate a minor/mini-merger event could have happened to the NW disk. CO(2-1) emission has non-detection in AGC 102004, reaching a noise level of 0.33 mK smoothed to 30 km s$^{-1}$. The upper limit of molecular gas mass in AGC 102004 is 2.1 $\times$ 10$^7$ M$\odot$ with X$_{\rm CO}$ = 3.02$\times$10$^{20}$ cm$^{-2}$ (K km s$^{-1}$)$^{-1}$. The M$_{\rm H_2}$/M$^{\rm corr}_{\rm HI}$ of AGC 102004 is lower than 0.0037 and lower than that of normal galaxies.

astro-ph.GA↗

arXiv2024

Towards Multi-modality Fusion and Prototype-based Feature Refinement for Clinically Significant Prostate Cancer Classification in Transrectal Ultrasound

Prostate cancer is a highly prevalent cancer and ranks as the second leading cause of cancer-related deaths in men globally. Recently, the utilization of multi-modality transrectal ultrasound (TRUS) has gained significant traction as a valuable technique for guiding prostate biopsies. In this study, we propose a novel learning framework for clinically significant prostate cancer (csPCa) classification using multi-modality TRUS. The proposed framework employs two separate 3D ResNet-50 to extract distinctive features from B-mode and shear wave elastography (SWE). Additionally, an attention module is incorporated to effectively refine B-mode features and aggregate the extracted features from both modalities. Furthermore, we utilize few shot segmentation task to enhance the capacity of classification encoder. Due to the limited availability of csPCa masks, a prototype correction module is employed to extract representative prototypes of csPCa. The performance of the framework is assessed on a large-scale dataset consisting of 512 TRUS videos with biopsy-proved prostate cancer. The results demonstrate the strong capability in accurately identifying csPCa, achieving an area under the curve (AUC) of 0.86. Moreover, the framework generates visual class activation mapping (CAM), which can serve as valuable assistance for localizing csPCa. These CAM images may offer valuable guidance during TRUS-guided targeted biopsies, enhancing the efficacy of the biopsy procedure.The code is available at https://github.com/2313595986/SmileCode.

eess.IV↗

arXiv2024

Tunable non-Hermitian skin effect via gain and loss

We investigate theoretically tunable non-Hermitian skin effect in systems with gain and loss, and find that bipolar (quadripolar) non-Hermitian skin effect characterized by topological invariants in one (two)-dimensional system. We also find the partial non-Hermitian skin effect with the coexistence of localized states and extended states. Both types of the non-Hermitian skin effect have not yet been predicted together in a single system. A feasible experimental scheme of our model is proposed to realize in electric circuits. Our investigation unveils a new type of non-Hermitian skin effect and enhance the tunability of the non-Hermitian systems by gain and loss other than the conventional non-reciprocal hopping.

physics.app-ph↗

arXiv2024

Efficient Multi-View Fusion and Flexible Adaptation to View Missing in Cardiovascular System Signals

The progression of deep learning and the widespread adoption of sensors have facilitated automatic multi-view fusion (MVF) about the cardiovascular system (CVS) signals. However, prevalent MVF model architecture often amalgamates CVS signals from the same temporal step but different views into a unified representation, disregarding the asynchronous nature of cardiovascular events and the inherent heterogeneity across views, leading to catastrophic view confusion. Efficient training strategies specifically tailored for MVF models to attain comprehensive representations need simultaneous consideration. Crucially, real-world data frequently arrives with incomplete views, an aspect rarely noticed by researchers. Thus, the View-Centric Transformer (VCT) and Multitask Masked Autoencoder (M2AE) are specifically designed to emphasize the centrality of each view and harness unlabeled data to achieve superior fused representations. Additionally, we systematically define the missing-view problem for the first time and introduce prompt techniques to aid pretrained MVF models in flexibly adapting to various missing-view scenarios. Rigorous experiments involving atrial fibrillation detection, blood pressure estimation, and sleep staging-typical health monitoring tasks-demonstrate the remarkable advantage of our method in MVF compared to prevailing methodologies. Notably, the prompt technique requires finetuning less than 3% of the entire model's data, substantially fortifying the model's resilience to view missing while circumventing the need for complete retraining. The results demonstrate the effectiveness of our approaches, highlighting their potential for practical applications in cardiovascular health monitoring. Codes and models are released at URL.

cs.LG↗

arXiv2024

Galactic Cirri at High Galactic Latitudes: I. Investigating Scatter in Slopes between Optical and far-Infrared Intensities

Based on the slopes between DESI $g,r$ and IRAS 100 $μm$ intensities, specifically $k_{g}$ and $k_{r}$, we have constructed a substantial sample of Galactic cirri. This sample covers 561.25 deg$^2$ at high Galactic latitudes (|b| $\geq$ 30$^{\circ}$), allowing for a systematic study of the physical parameters of the Galactic cirrus on a large scale, such as $g-r$ color, dust temperature, asymmetry factor and albedo. The ratio of $k_{g}$ and $k_{r}$ is consistent with the diffuse Galactic starlight model, suggesting that the diffuse starlight within our own Galaxy serves as the primary illumination source for the cirrus. Both $k_{g}$ and $k_{r}$ decrease slowly with increasing Galactic latitudes and IRAS 100 $μm$ intensities, while they do not have a correlation with Galactic longitudes. The distribution of $k_{g}$ and $k_{r}$ confirms a significant scatter in the slopes, reaching a factor of 4-5. Such large scatter cannot be explained by the weak correlation between the slopes and Galactic latitudes and IRAS 100 $μm$ intensities. Instead, it is attributed to substantial variations in the intrinsic properties of the dust, e.g., asymmetry factor and albedo. We propose that the properties of dust particles play a critical role in the observed scatter in slopes, making them the primary contributing factors. Moreover, the variations in dust properties within the cirrus are localized rather than exhibiting large-scale gradients.

astro-ph.GA↗

arXiv2024

A Prototype-Based Neural Network for Image Anomaly Detection and Localization

Image anomaly detection and localization perform not only image-level anomaly classification but also locate pixel-level anomaly regions. Recently, it has received much research attention due to its wide application in various fields. This paper proposes ProtoAD, a prototype-based neural network for image anomaly detection and localization. First, the patch features of normal images are extracted by a deep network pre-trained on nature images. Then, the prototypes of the normal patch features are learned by non-parametric clustering. Finally, we construct an image anomaly localization network (ProtoAD) by appending the feature extraction network with $L2$ feature normalization, a $1\times1$ convolutional layer, a channel max-pooling, and a subtraction operation. We use the prototypes as the kernels of the $1\times1$ convolutional layer; therefore, our neural network does not need a training phase and can conduct anomaly detection and localization in an end-to-end manner. Extensive experiments on two challenging industrial anomaly detection datasets, MVTec AD and BTAD, demonstrate that ProtoAD achieves competitive performance compared to the state-of-the-art methods with a higher inference speed. The source code is available at: https://github.com/98chao/ProtoAD.

cs.CV↗

arXiv2024

Low surface brightness galaxies from BASS+MzLS with Machine Learning

From $\sim$ 5000 deg$^{2}$ of the combination of the Beijing-Arizona Sky Survey (BASS) and Mayall $z$-band Legacy Survey (MzLS) which is also the northern sky region of the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, we selected a sample of 31,825 candidates of low surface brightness galaxies (LSBGs) with the mean effective surface brightness 24.2 $< \barμ_{\rm eff,g} <$ 28.8 mag arcsec$^{\rm -2}$ and the half-light radius 2.5$^{\prime\prime}$ $< r_{\rm eff} <$ 20$^{\prime\prime}$ based on the released photometric catalogue and the machine learning model. The distribution of the LSBGs is of bimodality in the $g$ - $r$ color, indicating the two distinct populations of the blue ($g$ - $r <$ 0.60) and the red ($g$ - $r >$ 0.60) LSBGs. The blue LSBGs appear spiral, disk or irregular while the red LSBGs are spheroidal or ellipitcal and spatially clustered. This trend shows that the color has a strong correlation with galaxy morphology for LSBGs. In the spatial distribution, the blue LSBGs are more uniformly distributed while the red ones are highly clustered, indicating that red LSBGs preferentially populated denser environment than the blue LSBGs. Besides, both populations have consistent distribution of ellipticity (median $ε\sim$ 0.3), half-light radius (median $r_{\rm eff} \sim$ 4$^{\prime\prime}$), and Sersic index (median $n$ = 1), implying the dominance of the full sample by the round and disk galaxies. This sample has definitely extended the studies of LSBGs to a regime of lower surface brightness, fainter magnitude, and broader other properties than the previously SDSS-based samples.

astro-ph.GA↗

arXiv2024

Astronomical Test with CMOS on the 60-cm Telescope at the Xinglong Observatory, NAOC

This work shows details of an evaluation of an observational system comprising a CMOS detector, 60-cm telescope, and filter complement. The system's photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, standard stars, and exoplanets. Photometry was precision achieved at the 0.02 mag level, while differential photometry of 0.004 mag precision. Extinction was found to be agreed with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with CCD across the optical wavelengths.

astro-ph.IM↗

arXiv2024

Almost Optically Dark Galaxies in DECaLS (I): Detection, Optical Properties and Possible Origins

We report the discovery of eight optical counterparts of ALFALFA extragalactic objects from DECaLS, five of which are discovered for the first time. These objects were flagged as HI emission sources with no optical counterparts in SDSS before. Multi-band data reveal their unusual physical properties. They are faint and blue ($g-r=-0.35\sim0.55$), with quite low surface brightness ($μ_{\rm g,peak}=24.88\sim26.41\,{\rm mag}/{\rm arcsec}^2$), irregular morphologies, low stellar masses ($log_{10}(M_{*}/M_\odot)=5.27\sim7.15$), low star formation rates ($SFR=0.21\sim9.24\times10^{-3}\,{M_\odot}\,{\rm yr}^{-1}$), and remarkably high HI-to-stellar mass ratios ($log_{10}(M_{\rm HI}/M_{*}) = 1.72\sim3.22$, except AGC\,215415). They deviate from the scaling relations between HI and optical properties defined by the ALFALFA sample and the baryonic Tully-Fisher relation. They agree well with the main sequence of star-forming galaxies but exhibit low star-forming efficiency. Based on their physical properties and environments, we speculate that six of these objects may have originated from tidal processes, while the remaining two appear to have isolated origins. They may have had a relatively calm evolutionary history and only begun to form stars recently.

astro-ph.GA↗

arXiv2024

Geometric and electronic properties of two kinds of CrO2 magnetic monolayers: D3d and D2h phases

Due to the high magnetic coupling strength between the Cr elements, the bulk phase CrO2 is one of several ferromagnetic oxides known to have the highest Curie temperature. When the dimensionality of the material is reduced from 3D to 2D, the 2D CrO2 system material is expected to maintain a high Curie temperature. In this work, we predict two new phases of CrO2 monolayer (D3d and D2h) by using first-principles calculations. We have found that the Curie temperature of 2D CrO2 is much lower than that of its bulk phase, but still remains as high as 191K, which is comparable to that of Fe2Cr2Ge6. In addition, 1L D3d-CrO2 is in the ferromagnetic state, while 1L D2h-CrO2 is in the antiferromagnetic state. Also, the different geometric structure affects its electrical properties: the 1L D3d-CrO2 is a half-metal while 1L D2h-CrO2 is a semiconductor. Our studies have shown that there is a wealth of electrical and magnetic properties in CrO2.

cond-mat.mtrl-sci↗

arXiv2024

Multi-modality transrectal ultrasound video classification for identification of clinically significant prostate cancer

Prostate cancer is the most common noncutaneous cancer in the world. Recently, multi-modality transrectal ultrasound (TRUS) has increasingly become an effective tool for the guidance of prostate biopsies. With the aim of effectively identifying prostate cancer, we propose a framework for the classification of clinically significant prostate cancer (csPCa) from multi-modality TRUS videos. The framework utilizes two 3D ResNet-50 models to extract features from B-mode images and shear wave elastography images, respectively. An adaptive spatial fusion module is introduced to aggregate two modalities' features. An orthogonal regularized loss is further used to mitigate feature redundancy. The proposed framework is evaluated on an in-house dataset containing 512 TRUS videos, and achieves favorable performance in identifying csPCa with an area under curve (AUC) of 0.84. Furthermore, the visualized class activation mapping (CAM) images generated from the proposed framework may provide valuable guidance for the localization of csPCa, thus facilitating the TRUS-guided targeted biopsy. Our code is publicly available at https://github.com/2313595986/ProstateTRUS.

eess.IV↗

arXiv2024

A spectral data release for 104 Type II Supernovae from the Tsinghua Supernova Group

We present 206 unpublished optical spectra of 104 type II supernovae obtained by the Xinglong 2.16m telescope and Lijiang 2.4m telescope during the period from 2011 to 2018, spanning the phases from about 1 to 200 days after the SN explosion. The spectral line identifications, evolution of line velocities and pseudo equivalent widths, as well as correlations between some important spectral parameters are presented. Our sample displays a large range in expansion velocities. For instance, the Fe~{\sc ii} $5169$ velocities measured from spectra at $t\sim 50$ days after the explosion vary from ${\rm 2000\ km\ s^{-1}}$ to ${\rm 5500\ km\ s^{-1}}$, with an average value of ${\rm 3872 \pm 949\ km\ s^{-1}}$. Power-law functions can be used to fit the velocity evolution, with the power-law exponent quantifying the velocity decline rate. We found an anticorrelation existing between H$β$ velocity at mid-plateau phase and its velocity decay exponent, SNe II with higher velocities tending to have smaller velocity decay rate. Moreover, we noticed that the velocity decay rate inferred from the Balmer lines (i.e., H$α$ and H$β$) have moderate correlations with the ratio of absorption to emission for H$α$ (a/e). In our sample, two objects show possibly flash-ionized features at early phases. Besides, we noticed that multiple high-velocity components may exist on the blue side of hydrogen lines of SN 2013ab, possibly suggesting that these features arise from complex line forming region. All our spectra can be found in WISeREP and Zenodo.

astro-ph.HE↗