arXiv subjects

Chuan Li

Publications and source records attributed to Chuan Li.

At least 91 records · Page 5Linked to original sources

arXiv2024

Secure Outsourced Decryption for FHE-based Privacy-preserving Cloud Computing

The demand for processing vast volumes of data has surged dramatically due to the advancement of machine learning technology. Large-scale data processing necessitates substantial computational resources, prompting individuals and enterprises to turn to cloud services. Accompanying this trend is a growing concern regarding data leakage and misuse. Homomorphic encryption (HE) is one solution for safeguarding data privacy, enabling encrypted data to be processed securely in the cloud. However, the encryption and decryption routines of some HE schemes require considerable computational resources, presenting non-trivial work for clients. In this paper, we propose an outsourced decryption protocol for the prevailing RLWE-based fully homomorphic encryption schemes. The protocol splits the original decryption into two routines, with the computationally intensive part executed remotely by the cloud. Its security relies on an invariant of the NTRU-search problem with a newly designed blinding key distribution. Cryptographic analyses are conducted to configure protocol parameters across varying security levels. Our experiments demonstrate that the proposed protocol achieves up to a $67\%$ acceleration in the client's local decryption, accompanied by a $50\%$ reduction in space usage.

cs.CR↗

arXiv2024

Association between a Failed Prominence Eruption and the Drainage of Mass from Another Prominence

Sympathetic eruptions of solar prominences have been studied for decades, however, it is usually difficult to identify their causal links. Here we present two failed prominence eruptions on 26 October 2022 and explore their connections. Using stereoscopic observations, the south prominence (PRO-S) erupts with untwisting motions, flare ribbons occur underneath, and new connections are formed during the eruption. The north prominence (PRO-N) rises up along with PRO-S, and its upper part disappears due to catastrophic mass draining along an elongated structure after PRO-S failed eruption. We suggest that the eruption of PRO-S initiates due to a kink instability, further rises up, and fails to erupt due to reconnection with surrounding fields. The elongated structure connecting PRO-N overlies PRO-S, which causes the rising up of PRO-N along with PRO-S and mass drainage after PRO-S eruption. This study suggests that a prominence may end its life through mass drainage forced by an eruption underneath.

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arXiv2024

Three-stage Acceleration of Solar Energetic Particles Detected by Parker Solar Probe

Coronal mass ejections (CMEs) drive powerful shocks and thereby accelerate solar energetic particles (SEPs) as they propagate from the corona into interplanetary space. Here we present the processes of three-stage particle acceleration by a CME-driven shock detected by the in situ spacecraft--Parker Solar Probe (PSP) on 2022 August 27. The onset of SEPs is produced by a fast CME with a speed of 1284 km/s when it propagates to $\sim$2.85 Rs. The second stage of particle acceleration occurs when the fast CME catches up and interacts with a preceding slow one in interplanetary space at $\sim$40 Rs ($\sim$0.19 au). The CME interaction is accompanied by an intense interplanetary type II radio enhancement. Such direct measurement of particle acceleration during interplanetary CME interaction/radio enhancement is rarely recorded in previous studies. The third stage of energetic storm particles is associated with the CME-driven shock passage of the PSP at $\sim$0.38 au. Obviously, harder particle spectra are found in the latter two stages than the first one, which can arise from a stronger shock produced by the CME interaction and the enriched seed particles inside the preceding CME.

astro-ph.SR↗

arXiv2024

The Solar Origin of an Intense Geomagnetic Storm on 2023 December 1st: Successive Slipping and Eruption of Multiple Magnetic Flux Ropes

The solar eruption that occurred on 2023 November 28 (SOL2023-11-28) triggered an intense geomagnetic storm on Earth on 2023 December 1. The associated Earth's auroras manifested at the most southern latitudes in the northern hemisphere observed in the past two decades. In order to explore the profound geoeffectiveness of this event, we conducted a comprehensive analysis of its solar origin to offer potential factors contributing to its impact. Magnetic flux ropes (MFRs) are twisted magnetic structures recognized as significant contributors to coronal mass ejections (CMEs), thereby impacting space weather greatly. In this event, we identified multiple MFRs in the solar active region and observed distinct slipping processes of the three MFRs: MFR1, MFR2, and MFR3. All three MFRs exhibit slipping motions at a speed of 40--137 km s$^{-1}$, extending beyond their original locations. Notably, the slipping of MFR2 extends to $\sim$30 Mm and initiate the eruption of MFR3. Ultimately, MFR1's eruption results in an M3.4-class flare and a CME, while MFR2 and MFR3 collectively produce an M9.8-class flare and another halo CME. This study shows the slipping process in a multi-MFR system, showing how one MFR's slipping can trigger the eruption of another MFR. We propose that the CME--CME interactions caused by multiple MFR eruptions may contribute to the significant geoeffectiveness.

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arXiv2024

Negative-energy waves in the vertical threads of a solar prominence

Solar prominences, intricate structures on the Sun's limb, have been a subject of fascination due to their thread-like features and dynamic behaviors. Utilizing data from the New Vacuum Solar Telescope (NVST), Chinese H_alpha Solar Explorer (CHASE), and Solar Dynamics Observatory (SDO), this study investigates the transverse swaying motions observed in the vertical threads of a solar prominence during its eruption onset on May 11, 2023. The transverse swaying motions were observed to propagate upward, accompanied by upflowing materials at an inclination of 31 degrees relative to the plane of the sky. These motions displayed small-amplitude oscillations with corrected velocities of around 3-4 km/s and periods of 13-17 minutes. Over time, the oscillations of swaying motion exhibited an increasing pattern in displacement amplitudes, oscillatory periods, and projected velocity amplitudes. Their phase velocities are estimated to be about 26-34 km/s. An important finding is that these oscillations'phase velocities are comparable to the upward flow velocities, measured to be around 30-34 km/s. We propose that this phenomenon is associated with negative-energy wave instabilities, which require comparable velocities of the waves and flows, as indicated by our findings. This phenomenon may contribute to the instability and observed disruption of the prominence. By using prominence seismology, the Alfven speed and magnetic field strength of the vertical threads have been estimated to be approximately 21.5 km/s and 2 Gauss, respectively. This study reveals the dynamics and magnetic properties of solar prominences, contributing to our understanding of their behavior in the solar atmosphere.

astro-ph.SR↗

arXiv2024

The Bright Rim Prominences according to 2.5D Radiative Transfer

Solar prominences observed close to the limb commonly include a bright feature that, from the perspective of the observer, runs along the interface between itself and the underlying chromosphere. Despite several idealised models being proposed to explain the underlying physics, a more general approach remains outstanding. In this manuscript we demonstrate as a proof-of-concept the first steps in applying the Lightweaver radiative transfer framework's 2.5D extension to a `toy' model prominence + VAL3C chromosphere, inspired by recent 1.5D experiments that demonstrated a significant radiative chromosphere--prominence interaction. We find the radiative connection to be significant enough to enhance both the electron number density within the chromosphere, as well as its emergent intensity across a range of spectral lines in the vicinity of the filament absorption signature. Inclining the viewing angle from the vertical, we find these enhancements to become increasingly asymmetric and merge with a larger secondary enhancement sourced directly from the prominence underside. In wavelength, the enhancements are then found to be the largest in both magnitude and horizontal extent for the spectral line cores, decreasing into the line wings. Similar behaviour is found within new Chinese H$α$ Solar Explorer (CHASE)/H$α$ Imaging Spectrograph (HIS) observations, opening the door for subsequent statistical confirmations of the theoretical basis we develop here.

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arXiv2024

Formation of Fan-spine Magnetic Topology through Flux Emergence and Subsequent Jet Production

Fan-spine magnetic structure, as a fundamental three-dimensional topology in magnetic reconnection theory, plays a crucial role in producing solar jets. However, how fan-spine configurations form in the solar atmosphere remains elusive. Using the Chinese H$α$ Solar Explorer (CHASE) and the Solar Dynamics Observatory (SDO), we present a case study on the complete buildup of fan-spine topology driven by flux emergence and the subsequent jet production. Two fan-spine structures and the two associated null points are present. Variations in null-point heights and locations were tracked over time during flux emergence. The north fan-spine structure is found to be created through magnetic reconnection between the newly emerged flux and the background field. Gentle reconnection persistently occurs after formation of the north fan-spine structure, resulting in weak plasma outflows. Subsequently, as flux emergence and magnetic helicity injection continue, the formation and eruption of mini-filaments after reconnection at the quasi-separatrix layer between the two nulls trigger three homologous jets. The CHASE observations reveal that the circular flare ribbon, inner bright patch, and remote brightening all exhibit redshifted signatures during these jet ejections. This work unveils the key role of flux emergence in the formation of fan-spine topology, and highlights the importance of mini-filaments for subsequent jet production.

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arXiv2024

Three-dimensional velocity fields of the solar filament eruptions detected by CHASE

The eruption of solar filaments, also known as prominences appearing off-limb, is a common phenomenon in the solar atmosphere. It ejects massive plasma and high-energy particles into interplanetary space, disturbing the solar-terrestrial environment. It is vital to obtain the three-dimensional velocity fields of erupting filaments for space-weather predictions. We derive the three-dimensional kinematics of an off-limb prominence and an on-disk filament, respectively, using the full-disk spectral and imaging data detected by the Chinese H$α$ Solar Explorer (CHASE). It is found that both the prominence and the filament experience a fast semicircle-shaped expansion at first. The prominence keeps propagating outward with an increasing velocity until escaping successfully, whereas the south leg of the prominence finally moves back to the Sun in a swirling manner. For the filament, the internal plasma falls back to the Sun associated with an anticlockwise rotation in the late ejection, matching the failed eruption without a coronal mass ejection. During the eruptions, both the prominence and the filament show material splitting along the line-of-sight direction, revealed by the bimodal H$α$ spectral profiles. For the prominence, the splitting begins at the top and gradually spreads to almost the whole prominence with a fast blue-shift component and a slow red-shift component. The material splitting in the filament is more fragmental. As shown by the present results, the CHASE full-disk spectroscopic observations make it possible to systematically study the three-dimensional kinematics of solar filament eruptions.

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arXiv2023

Observational signature of continuously operating drivers of decayless kink oscillation

Decayless kink oscillations, which are nearly omnipresent in the solar corona, are believed to be driven by continuously operating energy supply. In this letter, we investigate an external continuous excitation of an apparent decayless oscillation during an X1.1 flare on June 20, 2023 (SOL2023-06-20T16:42).The decayless kink oscillation was identified in the coronal loop at extreme ultraviolet (EUV) wavelengths and the associated flare quasi-periodic pulsations (QPPs) were simultaneously observed in passbands of hard X-ray (HXR), microwave, and ultraviolet (UV) emissions. The kink oscillation is detected as a transverse oscillation of the coronal loop, which reveals five apparent cycles with an average period of about 130-10 s. The oscillation amplitude does not show any significantly decay, suggesting a decayless oscillation. At the same time, the solar flare occurs in the vicinity of the oscillating loop and exhibits five main pulses in HXR, microwave, and UV emissions, which could be regarded as flare QPPs. They have similar periods of about 100-130 s, which may indicate successive and repetitive energy releases during the flare impulsive phase. The peak of each loop oscillation cycle appears to follow the pulse of the QPPs, suggesting that the transverse oscillation is closely associated with flare QPPs. Our observations support the scenario where the repetitive energy released following flare QPPs could be invoked as external, continuously operating drivers of the apparent decayless kink oscillation.

astro-ph.SR↗

arXiv2023

Simultaneous detection of flare-associated kink oscillations and extreme-ultraviolet waves

Kink oscillations, which are frequently observed in coronal loops and prominences, are often accompanied by extreme-ultraviolet (EUV) waves. However, much more needs to be explored regarding the causal relationships between kink oscillations and EUV waves. In this article, we report the simultaneous detection of kink oscillations and EUV waves that are both associated with an X2.1 flare on 2023 March 03 (SOL2023-03-03T17:39). The kink oscillations, which are almost perpendicular to the axes of loop-like structures, are observed in three coronal loops and one prominence. One short loop shows in-phase oscillation within the same period of 5.2 minutes at three positions. This oscillation could be triggered by the pushing of an expanding loop and interpreted as the standing kink wave. Time lags are found between the kink oscillations of the short loop and two long loops, suggesting that the kink wave travels in different loops. The kink oscillations of one long loop and the prominence are possibly driven by the disturbance of the CME, and that of another long loop might be attributed to the interaction of the EUV wave. The onset time of the kink oscillation of the short loop is nearly same as the beginning of an EUV wave. This fact demonstrates that they are almost simultaneous. The EUV wave is most likely excited by the expanding loop structure and shows two components. The leading component is a fast coronal wave, and the trailing one could be due to the stretching magnetic field lines.

astro-ph.SR↗

arXiv2023

Partial Eruption of Solar Filaments. I. Configuration and Formation of Double-decker Filaments

Partial eruptions of solar filaments are the typical representative of solar eruptive behavior diversity. Here we investigate a typical filament partial eruption event and present integrated evidence for configuration of the pre-eruption filament and its formation. The CHASE H$α$ observations reveal structured Doppler velocity distribution within the pre-eruption filament, where distinct redshift only appeared in the east narrow part of the south filament region and then disappeared after the partial eruption while the north part dominated by blueshift remained. Combining the SDO, ASO-S observations, and NLFFF modeling results, we verify that there were two independent material flow systems within the pre-flare filament, whose magnetic topology is a special double-decker configuration consisting of two magnetic flux ropes (MFRs) with opposite magnetic twist. During the formation of this filament system, continuous magnetic flux cancellation and footpoint motion were observed around its north end. Therefore, we propose a new double-decker formation scenario that the two MFRs composing such double-decker configuration originated from two magnetic systems with different initial connections and opposite magnetic twist. Subsequent magnetic reconnection with surrounding newly-emerging fields resulted in the motion of footpoint of the upper MFR to the region around footpoint of the lower MFR, thus leading to eventual formation of the double-decker configuration consisting of two MFRs with similar footpoints but opposite signs of magnetic twist. These results provide a potential way to determine unambiguously the progenitor configuration of a partial-eruptive filament and reveal a special type of double-decker MFR configuration and a new double-decker formation scenario.

astro-ph.SR↗

arXiv2023

Simultaneous Horizontal and Vertical Oscillation of a Quiescent Filament observed by CHASE and SDO

In this paper, we present the imaging and spectroscopic observations of the simultaneous horizontal and vertical large-amplitude oscillation of a quiescent filament triggered by an EUV wave on 2022 October 02. Particularly, the filament oscillation involved winking phenomenon in Ha images and horizontal motions in EUV images. Originally, a filament and its overlying loops across AR 13110 and 13113 erupted with a highly inclined direction, resulting in an X1.0 flare and a non-radial CME. The fast lateral expansion of loops excited an EUV wave and the corresponding Moreton wave propagating northward. Once the EUV wavefront arrived at the quiescent filament, the filament began to oscillate coherently along the horizontal direction and the winking filament appeared concurrently in Ha images. The horizontal oscillation involved an initial amplitude of 10.2 Mm and a velocity amplitude of 46.5 km/s, lasting for 3 cycles with a period of 18.2 minutes and a damping time of 31.1 minutes. The maximum Doppler velocities of the oscillating filament are 18 km/s (redshift) and 24 km/s (blueshift), which was derived from the spectroscopic data provided by CHASE/HIS. The three-dimensional velocity of the oscillation is determined to be 50 km/s at an angle of 50 to the local photosphere plane. Based on the wave-filament interaction, the minimum energy of the EUV wave is estimated to be 2.7 10 20 J. Furthermore, this event provides evidence that Moreton wavesshould be excited by the highly inclined eruptions.

astro-ph.SR↗

arXiv2023

Internal activities in a solar filament and heating to its threads

Filaments are one of the most common features in the solar atmosphere, and are of significance in solar, stellar and laboratory plasma physics. Using data from the Chinese H$α$ Solar Explorer, the Solar Upper Transition Region Imager and the Solar Dynamics Observatory, we report on multiwavelength imaging and spectral observations of the activation of a small filament. The filament activation produces several localized dynamic brightenings, which are probably produced by internal reconnections of the braided magnetic fields in the filament. The filament expands during the activation and its threads reconnect with the ambient magnetic fields, which leads to the formation of hot arcades or loops overlying the filament. The thermal energy of each of these localized brightenings is estimated in the order of $10^{25}-10^{27} erg$ and the total energy is estimated to be $\sim1.77 \times 10^{28} erg$. Our observations demonstrate that the internal magnetic reconnections in the filament can lead to localized heating to the filament threads and prompt external reconnections with ambient corona structures, and thus could contribute to the energy and mass transferring into the corona.

astro-ph.SR↗

arXiv2023

Understanding the Lateral Drifting of an Erupting Filament with a Data-constrained Magnetohydrodynamic Simulation

Solar filaments often exhibit rotation and deflection during eruptions, which would significantly affect the geoeffectiveness of the corresponding coronal mass ejections (CMEs). Therefore, understanding the mechanisms that lead to such rotation and lateral displacement of filaments is a great concern to space weather forecasting. In this paper, we examine an intriguing filament eruption event observed by the Chinese Hα Solar Explorer (CHASE) and the Solar Dynamics Observatory (SDO). The filament, which eventually evolves into a CME, exhibits significant lateral drifting during its rising. Moreover, the orientation of the CME flux rope axis deviates from that of the pre-eruptive filament observed in the source region. To investigate the physical processes behind these observations, we perform a data-constrained magnetohydrodynamic (MHD) simulation. Many prominent observational features in the eruption are reproduced by our numerical model, including the morphology of the eruptive filament, eruption path, and flare ribbons. The simulation results reveal that the magnetic reconnection between the flux-rope leg and neighboring low-lying sheared arcades may be the primary mechanism responsible for the lateral drifting of the filament material. Such a reconnection geometry leads to flux-rope footpoint migration and a reconfiguration of its morphology. As a consequence, the filament material hosted in the flux rope drifts laterally, and the CME flux rope deviates from the pre-eruptive filament. This finding underscores the importance of external magnetic reconnection in influencing the orientation of a flux rope axis during eruption.

astro-ph.SR↗

arXiv2023

Utilizing Large Language Models for Natural Interface to Pharmacology Databases

The drug development process necessitates that pharmacologists undertake various tasks, such as reviewing literature, formulating hypotheses, designing experiments, and interpreting results. Each stage requires accessing and querying vast amounts of information. In this abstract, we introduce a Large Language Model (LLM)-based Natural Language Interface designed to interact with structured information stored in databases. Our experiments demonstrate the feasibility and effectiveness of the proposed framework. This framework can generalize to query a wide range of pharmaceutical data and knowledge bases.

cs.CL↗

arXiv2023

Spectral Observations and Modeling of a Solar White-light Flare Observed by CHASE

The heating mechanisms of solar white-light flares remain unclear. We present an X1.0 white-light flare on 2022 October 2 (SOL2022-10-02T20:25) observed by the Chinese \ha\ Solar Explorer (CHASE) that provides two-dimensional spectra in the visible light for the full solar disk with a seeing-free condition. The flare shows a prominent enhancement of $\sim$40\% in the photospheric \fe\ line at 6569.2 Å, and the nearby continuum also exhibits a maximum enhancement of $\sim$40\%. For the continuum near the \fe\ line at 6173 Å from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO), it is enhanced up to $\sim$20\%. At the white-light kernels, the \fe\ line at 6569.2 Å has a symmetric Gaussian profile that is still in absorption and the H$α$ line at 6562.8 Å displays a very broad emission profile with a central reversal plus a red or blue asymmetry. The white-light kernels are co-spatial with the microwave footpoint sources observed by the Expanded Owens Valley Solar Array (EOVSA) and the time profile of the white-light emission matches that of the hard X-ray emission above 30 keV from the Gamma-ray Burst Monitor (GBM) on Fermi. These facts indicate that the white-light emission is qualitatively related to a nonthermal electron beam. We also perform a radiative hydrodynamic simulation with the electron beam parameters constrained by the hard X-ray observations from Fermi/GBM. The result reveals that the white-light enhancement cannot be well explained by a pure electron-beam heating together with its induced radiative backwarming but may need additional heating sources such as \alfven\ waves.

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arXiv2023

Observational signatures of electron-driven chromospheric evaporation in a white-light flare

We investigate observational signatures of explosive chromospheric evaporation during a white-light flare (WLF) that occurred on 2022 August 27. Using the moment analysis, bisector techniques, and the Gaussian fitting method, red-shifted velocities of less than 20 km/s are detected in low-temperature spectral lines of Ha, C I and Si IV at the conjugated flare kernels, which could be regarded as downflows caused by chromospheric condensation. Blue-shifted velocities of about 30-40 km/s are found in the high-temperature line of Fe XXI, which can be interpreted as upflows driven by chromospheric evaporation. A nonthermal hard X-ray (HXR) source is co-spatial with one of the flare kernels, and the Doppler velocities are temporally correlated with the HXR fluxes. The nonthermal energy flux is estimated to be at least (1.3+-0.2)*10^10 erg/s/cm^2. The radiation enhancement at Fe I 6569.2 A and 6173 A suggests that the flare is a WLF. Moreover, the while-light emission at Fe I 6569.2 A is temporally and spatially correlated with the blue shift of Fe XXI line, suggesting that both the white-light enhancement and the chromospheric evaporation are triggered and driven by nonthermal electrons. All our observations support the scenario of an electron-driven explosive chromospheric evaporation in the WLF.

astro-ph.SR↗

arXiv2023

Transverse vertical oscillations during the contraction and expansion of coronal loops

In this paper, we carry out a detailed analysis of the M1.6 class eruptive flare occurring in NOAA active region 13078 on 2022 August 19. The flare is associated with a fast coronal mass ejection (CME) propagating in the southwest direction with an apparent speed of $\sim$926 km s$^{-1}$. Meanwhile, a shock wave is driven by the CME at the flank. The eruption of CME generates an extreme-ultraviolet (EUV) wave expanding outward from the flare site with an apparent speed of $\geq$200 km s$^{-1}$. As the EUV wave propagates eastward, it encounters and interacts with the low-lying adjacent coronal loops (ACLs), which are composed of two loops. The compression of EUV wave results in contraction, expansion, and transverse vertical oscillations of ACLs. The commencements of contraction are sequential from western to eastern footpoints and the contraction lasts for $\sim$15 minutes. The speeds of contraction lie in the range of 13$-$40 km s$^{-1}$ in 171 Å and 8$-$54 km s$^{-1}$ in 193 Å. A long, gradual expansion follows the contraction at lower speeds. Concurrent vertical oscillations are superposed on contraction and expansion of ACLs. The oscillations last for 2$-$9 cycles and the amplitudes are $\leq$4 Mm. The periods are between 3 to 12 minutes with an average value of 6.7 minutes. The results show rich dynamics of coronal loops.

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