arXiv subjects

Ye Xu

Publications and source records attributed to Ye Xu.

At least 19 recordsLinked to original sources

arXiv2026

Viscoelasticity reshapes the frequency response of a rotating magnetic particle

A magnetic particle driven by a rotating magnetic field undergoes a transition from synchronous to asynchronous rotation at a critical driving frequency. The asynchronous dynamics is well understood in Newtonian fluids but remains unclear in viscoelastic media. Here, we develop a theoretical description of the asynchronous rotation of a magnetic particle in a Jeffreys-type viscoelastic fluid. The particle's time-averaged angular velocity exhibits a nontrivial frequency dependence that changes from non-monotonic to monotonic as the polymer relaxation time increases. This behavior is explained by the interplay among magnetic driving, viscoelastic relaxation, and frequency-dependent viscous dissipation. We further derive an asymptotic expression that captures the non-monotonic dependence. These results clarify how solvent and polymer contributions jointly control asynchronous rotation and provide a physical basis for guiding relevant applications in complex fluids.

cond-mat.soft↗

arXiv2026

Star Formation in the H II Region Sh 2-205: 3D Morphology and Kinematics from Young Stars and Molecular Gas

Using Gaia astrometry of young stars combined with CO observations, we present the first systematic three-dimensional (3D) analysis of the structure, kinematics, and evolutionary history of the star-forming regions in the environs of the H II region Sh 2-205 (S205). S205 exhibits a complex morphology and coherent expansion on both global and subregional scales. We identify several O9-B1 stars and a 0.56 Myr old pulsar that are likely associated with the region. A momentum estimate suggests that feedback from these objects may account for the observed overall expansion. Trace-back analysis of the expansion, combined with color-magnitude diagram fitting for young star clusters, indicates at least two episodes of star formation. These results reveal a complex star-formation history of S205 and provide new insights into its 3D evolution.

astro-ph.GA↗

arXiv2026

Dynamics of a microroller under confinement

Rotating particles can translate when placed near a surface, forming microrollers with a wide range of biomedical and microfluidic applications. In this work, we investigate the dynamics of microrollers in confined microchannels with different geometries by combining experiments, numerical simulations, and scaling analysis. In constricted channels, we find that the translational velocity of a microroller decreases as it approaches the constricted region. In both rectangular and cylindrical channels, velocity reversal occurs as the characteristic channel width decreases. Using the force-free condition for free translation, we develop a systematic scaling framework that can be generalized to different channel geometries. The scaling analysis yields functional dependences of the translational velocity on the degree of confinement, which agree well with both experiments and simulations. Importantly, we demonstrate that the viscous stress generated by the far-field rotlet flow governs the observed velocity reduction and reversal, while the translational resistance resulting from the near-field shear flow suppresses translation under tight confinement. The distinct roles of these flow components revealed by our analysis may provide practical guidance for controlling microroller dynamics in confined fluid environments.

physics.flu-dyn↗

arXiv2026

Mapping the Milky Way with Masers

SKA-VLBI is poised to revolutionize our understanding of the Galactic structure through its unprecedented astrometric precision and sensitivity. As a next-generation facility, it will answer long-standing questions about the Galactic structure by mapping its entire spiral structure in detail, spanning from the solar neighborhood, through the Galactic Center, to the far side of the Milky Way. Its access to the Southern sky will allow us to obtain more precise 3D parameters of the Galactic bar, reveal the nature of the 3-kpc Arm, and clarify the dynamical coupling between the bar and the spiral arms. By leveraging high-precision astrometry of numerous celestial objects with SKA-VLBI, the Galactic fundamental parameters such as the Solar motion and the Galactic rotation curve can be constrained more precisely. These advancements will not only elucidate the structure of our Milky Way, but also provide benchmarks for understanding barred spiral galaxies in general. Furthermore, they are important for advancing our knowledge of cosmological structure formation. The capabilities of SKA-VLBI will open a new era of high precision Galactic astrometry.

astro-ph.GA↗

arXiv2026

East Asian VLBI Network astrometry toward the star-forming region G040.96+02.48 in the Extreme Outer Galaxy

Accurate astrometric measurements for star-forming regions located on the far side of the Milky Way remain scarce. In this work, we present the astrometric results for a 22\,GHz water maser associated with star-forming region G040.96+02.48 located on the far side of the Milky Way, using the East Asian VLBI Network. The target water maser's proper motion was determined to be ($\mu_{\alpha}\cos\delta, \mu_{\delta}$) = ($-2.06_{-0.51}^{+0.53}$, $-2.95_{-0.44}^{+0.45}$)~mas~yr$^{-1}$. The derived three-dimensional kinematic distance to the star-forming region is 20.2$\pm$3.2\,kpc, placing it slightly outside the Outer Scutum$-$Centaurus Arm. The corresponding vertical height of 872$\pm$139\,pc indicates a significant warp of the outer Galactic disk, which is in good agreement with the latest precessing warp model. Moreover, the resulting peculiar motions reveal a complex kinematic pattern, characterized by a large outward radial velocity of $-32\pm$18\,km~s$^{-1}$. Our observations substantially expand the valuable sample of star-forming regions with accurate astrometric measurements in the Extreme Outer Galaxy.

astro-ph.GA↗

arXiv2026

Polymeric Solvents Control Swelling-Induced Surface Creasing

Surface creasing in swelling polymer gels is commonly attributed to compressive strain or interlayer mismatch, yet its general control remains unclear. Here we show that solvent polymerization degree $N_{\rm s}$ provides an independent control parameter for crease onset in surface-bound polydimethylsiloxane gels swollen by silicone oils. Despite nearly identical swelling kinetics and through-thickness solvent concentration profiles, we observe a transition from creased to stable surfaces with increasing $N_{\rm s}$. A theory coupling swelling thermodynamics and mechanical stability reveals that polymeric solvents reduce the mixing entropy and thereby modify the osmotic pressure, allowing $N_{\rm s}$ to tune separately the equilibrium swelling and the crease threshold. This framework captures the stability boundary across solvent polymerization degree and network elasticity. These results identify polymeric solvents as active thermodynamic-mechanical regulators of swelling-induced surface.

cond-mat.soft↗

arXiv2025

The Milky Way Imaging Scroll Painting Survey: Data Release 1

We present the first data release (DR1) of the Milky Way Imaging Scroll Painting (MWISP) survey, a mapping in the J=(1-0) transition lines of 12CO, 13CO, and C18O toward the northern Galactic plane during 2011-2022. The MWISP survey was conducted using the PMO 13.7 m telescope at a spatial resolution of approximately 50" and a velocity resolution of 0.16 km/s at 115 GHz. DR1 fully covered 2310 square degrees within the Galactic longitude (l) and latitude (b) range of 9.75 deg =< l =< 229.75 deg and |b| =< 5.25 deg. The surveyed area was divided into cell units of 30'x30' for practical purposes and On-The-Fly (OTF) mapping was performed toward each target cell unit. The data were regridded into a regular 3D datacube in l-b-V_LSR with a pixel size of 30" in l-b axes and 0.16 km/s in theV_LSR axis. The median rms noise is 0.47 K, 0.25 K, and 0.25 K for 12CO, 13CO, and C18O, respectively. The equivalent 3 sigma sensitivity in 12CO luminosity is approximately 0.23 K km/s, making MWISP the most sensitive survey of its kind. In this paper, we describe the survey data, including the calibration, data cleaning, data mosaic processes, and the data products. The final mosaicked data cubes contain about 3.33x10^7 spectra (pixels) for each CO isotopologue line. Color composite images, made from the intensities of the isotopologue lines, and some concise descriptions are provided. We constructed a molecular cloud catalog based on the mosaicked 12CO data cube using the clustering algorithm DBSCAN, detecting 103,517 molecular clouds, 10,790 of which exhibit 13CO emission and 304 of which show C18O emission. Based on the histogram of voxel brightness temperature, we estimated a total 12CO flux of 7.69+/-0.38x10^7 K km/s arcmin^2, 82% of which is captured by the DBSCAN algorithm. The data, together with the cloud sample, provide unique information on molecular gas in the northern Milky Way.

astro-ph.GA↗

arXiv2025

Measurement of Milli-Charged Particles with a running electromagnetic coupling constant at IceCube

It is postulated that heavy dark matter $\phi$ with a mass on the order of TeV, once captured by the Earth, can decay into relativistic milli-charged particles (MCPs). These MCPs are potentially detectable at the IceCube neutrino telescope. In this study, MCPs are modeled within the massless hidden photon framework, where they interact with nuclei via a running electromagnetic coupling constant, thereby enabling the prediction of their expected event rates and fluxes at IceCube. The expected number of background neutrino events at IceCube has also been evaluated. Under the assumption that no signal events are observed over a 10-year period at IceCube, upper limits on the MCP flux have been derived at the 90\% confidence level. The results suggest that MCPs originating from the Earth's core could be directly detected at IceCube at energies around $\mathcal{O}(1\ \text{TeV})$ for a fractional charge-squared range of $5.65\times10^{-5} \lesssim \epsilon^2 \lesssim 1.295\times10^{-3}$. Furthermore, with 10 years of IceCube data, a new region in the $m_{\text{MCP}}$-$\epsilon$ parameter space--specifically, $4\ \text{GeV} < m_{\text{MCP}} < 100\ \text{GeV}$ and $5.51\times10^{-2} < \epsilon < 0.612$--has been excluded.

astro-ph.HE↗

arXiv2025

Leveraging Large Language Models for Career Mobility Analysis: A Study of Gender, Race, and Job Change Using U.S. Online Resume Profiles

We present a large-scale analysis of career mobility of college-educated U.S. workers using online resume profiles to investigate how gender, race, and job change options are associated with upward mobility. This study addresses key research questions of how the job changes affect their upward career mobility, and how the outcomes of upward career mobility differ by gender and race. We address data challenges -- such as missing demographic attributes, missing wage data, and noisy occupation labels -- through various data processing and Artificial Intelligence (AI) methods. In particular, we develop a large language models (LLMs) based occupation classification method known as FewSOC that achieves accuracy significantly higher than the original occupation labels in the resume dataset. Analysis of 228,710 career trajectories reveals that intra-firm occupation change has been found to facilitate upward mobility most strongly, followed by inter-firm occupation change and inter-firm lateral move. Women and Black college graduates experience significantly lower returns from job changes than men and White peers. Multilevel sensitivity analyses confirm that these disparities are robust to cluster-level heterogeneity and reveal additional intersectional patterns.

cs.CY↗

arXiv2025

Measurement of Downward-going Milli-charged particles beyond GZK cutoff at the Pierre Auger Observatory

It is assumed that superheavy dark matter particles (SHDM, $\phi$) with $\mathcal{O}$(ZeV) mass may decay to relativistic milli-charged particles (MCPs, $\chi$) via a channel $\phi\to\chi\bar{\chi}$. The downward-going MCPs passing through the atmosphere can be searched for at the Pierre Auger observatory (Auger). The massless hidden photon model is taken for MCPs to interact with nuclei, so that we evaluated the numbers and fluxes of expected MCPs at Auger assuming 14 years of Auger data. The hybrid data of Auger was fitted with the flux of UHE MCPs exceeding GZK-cutoff energy. Then the corresponding upper limits on $\epsilon^2$ are calculated at 90\% C. L.. These results indicate that MCPs can be searched for with $\epsilon^2\gtrsim 3.73\times10^{-5}$ at Auger, when $m_{\phi}=2\times10^{21}$ eV and $\tau_{\phi}=10^{27}$ s. And a new region of 10$^{10}$ eV < $m_{MCP}$ < 10$^{11.6}$ eV and $\epsilon$ > $2.02\times10^{-2}$ is ruled out in the $m_{MCP}$-$\epsilon$ plane with 14 years of Auger data. These results indicate potential existence of MCPs and SHDM in the Universe.

astro-ph.HE↗

arXiv2025

Polymer-modulated evaporation flow enables scalable self-assembly of highly aligned nanowires

Highly aligned nanowire networks are essential for enabling anisotropic optical, electrical, and sensing functionalities in next-generation devices. However, achieving such alignment typically requires complex fabrication methods or high-energy processing. Here, we present a simple and scalable self-assembly strategy that uses a viscosity-enhancing polymer additive to modulate fluid flows during solvent evaporation. The addition of carboxymethylcellulose sodium (CMC-Na) reshapes the evaporation-driven flow field and generates a compressional flow region near the drying edge. Within this region, rotation-inducing velocity gradients progressively align silver nanowires (AgNWs) into highly ordered arrays. This unique mechanism yields uniform AgNW coatings with a high degree of nanowire alignment and tunable areal density across centimeter-scale areas. The resulting films exhibit strong broadband anisotropy, including polarization-dependent transmission in both visible and terahertz (THz) regimes and angle-dependent electrical conductivity. The approach also integrates naturally with dip-coating-based shear alignment, enabling programmable control over alignment direction and spatial patterning. This work establishes a robust, polymer-enabled mechanism for bottom-up nanowire alignment and offers a passive, energy-efficient route for fabricating anisotropic nanostructured coatings.

cond-mat.soft↗

arXiv2025

On-Device Crack Segmentation for Edge Structural Health Monitoring

Crack segmentation can play a critical role in Structural Health Monitoring (SHM) by enabling accurate identification of crack size and location, which allows to monitor structural damages over time. However, deploying deep learning models for crack segmentation on resource-constrained microcontrollers presents significant challenges due to limited memory, computational power, and energy resources. To address these challenges, this study explores lightweight U-Net architectures tailored for TinyML applications, focusing on three optimization strategies: filter number reduction, network depth reduction, and the use of Depthwise Separable Convolutions (DWConv2D). Our results demonstrate that reducing convolution kernels and network depth significantly reduces RAM and Flash requirement, and inference times, albeit with some accuracy trade-offs. Specifically, by reducing the filer number to 25%, the network depth to four blocks, and utilizing depthwise convolutions, a good compromise between segmentation performance and resource consumption is achieved. This makes the network particularly suitable for low-power TinyML applications. This study not only advances TinyML-based crack segmentation but also provides the possibility for energy-autonomous edge SHM systems.

cs.LG↗

arXiv2025

Cloud-cloud collision and star formation in G013.313+0.193

We study the G013.313+0.193 G013.313 region, a complex environment characterized by molecular cloud interactions indicative of cloud-cloud collision (CCC). Observations of the NH3(1,1) and (2,2) inversion transitions were obtained using the Nanshan 26 m radio telescope, while HCO+ (1-0), 12CO, 13CO, and C18O(1-0) transitions from the Purple Mountain Observatory Delingha 14 m telescope. Archival data are also included. We identified key observational signatures of CCC, including complementary spatial distributions, U-shaped structures, bridge features, and V-shaped velocity distributions. The position-velocity diagrams (P-V) reveal clear indications of gas interaction between two velocity components, suggesting an ongoing collision at an estimated angle of approximately 45 degree to the line of sight. The estimated collision timescale is 0.35-1.03 Myr, aligned with the inferred ages of young stellar objects (YSOs) in the region, supporting the hypothesis of collision-induced star formation. Hub-filament system (HFS) are identified in the compressed gas region, where filaments converge toward a dense hub, suggesting the CCC as a potential driver of HFS formation and massive star formation. The high column density suggests favorable conditions for the formation of massive stars. Although alternative kinematic drivers such as longitudinal collapse and shear motion are considered, CCC remains the most plausible explanation for the observed features. Our findings contribute to our understanding of the mechanisms of cloud dynamics and massive star formation in turbulent molecular environments.

astro-ph.GA↗

arXiv2025

Discovery of a high-velocity cloud of the Milky Way as a potential dark galaxy

High-velocity clouds (HVCs) are composed of neutral hydrogen (HI) moving at velocities that deviate from the general rotational motion of the Milky Way. Currently, the origins of the HVCs remain poorly known due to the difficulty in determining their distance and the lack of any other suitable identification. Here we report the detection of a compact gas clump in HVC AC-I, which displays characteristics typical of a disk galaxy, named AC G185.0-11.5, using the HI observations. We estimated the distance of AC G185.0-11.5 to be about 277.7 kpc using the Baryonic Tully-Fisher relation and constrained its HI gas mass to be between 3.0*10^7 and 4.7*10^8 solar masses. The distance determination indicates that the HVC AC-I hosting AC G185.0-11.5 is an extragalactic object in the Local Group. The absence of molecular gas and an optical counterpart for AC G185.0-11.5 implies that it may be a rare dark galaxy.

astro-ph.GA↗

arXiv2025

Uniform deposition of particles in large scale by drying of binary droplets

The evaporation of liquid droplets often results in a ring-like deposition pattern of particles, presenting challenges for applications requiring highly uniform patterns. Despite extensive efforts to suppress the coffee ring effect, achieving a uniform particle distribution remains a great challenge due to the complex and non-equilibrium nature of the evaporation process. In this work, we introduce and demonstrate a one-step drying method for binary droplets (water and 2-methoxyethanol) that produces uniform deposition of nano- and micro-particles. By adjusting the initial water volume fraction, we effectively control the interplay between capillary and Marangoni flows, resulting in deposition patterns that vary from coffee ring to uniform and to volcano-like. Through both theoretical and experimental analyses, we determine the conditions necessary for achieving such high uniformity. This approach requires no special substrate treatment, particle modification, or controlled environments, and works for various particles, including silica and polystyrene. Our method provides a robust solution for fabricating uniform patterns that are crucial for many practical applications, ranging from printing to microelectronics to bio-pharmacy.

cond-mat.soft↗

arXiv2025

Response of magnetic particle to rotating magnetic field in viscoelastic fluid

The rotational dynamics of a freely suspended ferromagnetic particle in viscoelastic fluid subjected to a rotating magnetic field is studied by experiments and theory. Our result reveals that when the characteristic relaxation time of the fluid is much smaller than the inverse critical field frequency, the particle's rotation behavior aligns with that in Newtonian fluids. Increasing the relaxation time enhances the time-averaged rotation frequency of the particle that undergo asynchronous rotation. Moreover, the critical frequency is shown to scale linearly with the magnetic field intensity and inversely with the fluid's zero-shear viscosity. Our work is expected to guide precise manipulation of ferromagnetic particles in biomedical systems where viscoelastic environments dominate.

cond-mat.soft↗

arXiv2025

Coherent Turning Behaviors Revealed Across Adherent Cells

Adherent cells have long been known to display two modes during migration: a faster mode that is persistent in direction and a slower one where they turn. Compared to the persistent mode, the turns are less studied. Here we develop a simple yet effective protocol to isolate the turns quantitatively. With the protocol, we study different adherent cells in different morphological states and find that, during turns, the cells behave as rotors with constant turning rates but random turning directions. To perform tactic motion, the cells bias the sign of turning towards the stimuli. Our results clarify the bimodal kinematics of adherent cell migration. Compared to the rotational-diffusion-based turning dynamics - which has been widely implemented, our data reveal a distinct picture, where turns are governed by a deterministic angular velocity.

physics.bio-ph↗

arXiv2025

Calibrating the Color-Magnitude Relation of M Giants by Using Open Clusters

M giants, with their distinctive properties such as high luminosity, serve as excellent indicators for mapping the structure of the Milky Way. The distance to distant M giants can be determined by using the color-magnitude relation (CMR), which is derived from color-magnitude diagrams of specific systems in previous studies. In this work, we aimed to achieve more accurate distance determination for M giants by focusing on open clusters (OCs) with a large number of member stars and thus improve the CMR. For the first time, we compiled a census of OCs harboring M giants using Gaia Data Release 3 (DR3) and Large Sky Area Multi-Object Fiber Spectroscopic Telescope Data Release 9. We identified 58 M giants associated with 43 OCs and obtained their astrometric and photometric parameters from Gaia DR3. Using the distances of these OCs, we derived the CMR for M giants as a linear correlation, expressed as $M_{Ks}=3.85-8.26(J-K_s$). This linear relation proved superior to the empirical distance relation in characterizing the CMR of M giants. The photometric distances of M giants derived from the CMR are consistent with the parallax distances from Gaia and known spectroscopic distances, with median deviations of 1.5% and 2.3%, respectively. Using the distances of M giants derived from the CMR, we computed their radial velocity ($V_R$), azimuthal velocity ($V{\phi}$), and vertical velocity ($V_Z$), respectively. The distributions of these velocities revealed key features of the Galactic disk, including oscillation, north-south rotational asymmetry, and warp. These findings are consistent with previous studies and further validate the reliability of the derived CMR.

astro-ph.SR↗