TY - JOUR A1 - Liu, Rui A1 - Wen, Tao A1 - Amalberti, Julien A1 - Zheng, Jian A1 - Hao, Fang A1 - Jiang, Dingchuan T1 - The dichotomy in noble gas signatures linked to tectonic deformation in Wufeng-Longmaxi Shale, Sichuan Basin JF - Chemical geology : official journal of the European Association for Geochemistry N2 - Geochemical homogeneity in shale is often assumed when tracing subsurface fluids and characterizing sedimentary basins. This study presents measurements of the bulk gas composition, stable isotopes, and noble gas volume fraction and isotopes for shale gas samples collected from gas wells in the Wufeng-Longmaxi Shale, the southern Sichuan Basin, China. The dryness [C-1 /(C-2 + C-3)] ranging from 166.3 to 251.2, combined with delta C-13(1) and delta DC1 that vary from -28.8 to -27.3 parts per thousand and - 153 to -145 parts per thousand, respectively, point to a late mature thermogenic origin of hydrocarbon gas. He-3/He-4 ratios of gas samples are around 0.01 times the air value suggesting dominantly crust-derived He. Ne-21/Ne-22 and Ar-40/Ar-36 ratios of many gas samples are higher than the corresponding air values indicating the mixing of crustal and atmospheric noble gases. Multiple dichotomous patterns are observed in noble gas signatures of forelimb and backlimb samples, and depression and crest samples. Ne-20/Ne-22 ratios of some crest samples are higher than that of depression samples in the backlimb, pointing to the presence of diffusion-driven fractionation that is likely caused by the long-distance migration from depression to crest. Elemental ratios of air-derived noble gas isotopes - Ne-22/Ar-36, Kr-84/Ar-36, and Xe-132/Ar-36 are compared to the recharge water values, suggesting the interactions of oil, gas, and water phases in the shale over geologic time. Forelimb samples generally display older ages than backlimb samples, indicating a larger flux of external radiogenic He-4 due to the higher density of deep faults in the forelimb area caused by the basementinvolved deformation. The basement-involved deformation also causes pore collapse especially in the forelimb leading to a lower porosity that results in a more pristine noble gas signature in the forelimb due to the reduced impact of younger recharge water. KW - reservoir compartmentalization KW - diffusion KW - isotope fractionation KW - phase KW - partitioning KW - noble gas Y1 - 2021 U6 - https://doi.org/10.1016/j.chemgeo.2021.120412 SN - 0009-2541 SN - 1872-6836 VL - 581 PB - Elsevier CY - New York, NY [u.a.] ER - TY - JOUR A1 - Chen, Jialin A1 - Su, Yingna A1 - Liu, Rui A1 - Kliem, Bernhard A1 - Zhang, Qingmin A1 - Ji, Haisheng A1 - Liu, Tie T1 - Partial eruption, confinement, and twist buildup and release of a double-decker filament JF - The astrophysical journal : an international review of spectroscopy and astronomical physics. N2 - We investigate the failed partial eruption of a filament system in NOAA AR 12104 on 2014 July 5, using multiwavelength EUV, magnetogram, and H alpha observations, as well as magnetic field modeling. The filament system consists of two almost co-spatial segments with different end points, both resembling a C shape. Following an ejection and a precursor flare related to flux cancellation, only the upper segment rises and then displays a prominent twisted structure, while rolling over toward its footpoints. The lower segment remains undisturbed, indicating that the system possesses a double-decker structure. The erupted segment ends up with a reverse-C shape, with material draining toward its footpoints, while losing its twist. Using the flux rope insertion method, we construct a model of the source region that qualitatively reproduces key elements of the observed evolution. At the eruption onset, the model consists of a flux rope atop a flux bundle with negligible twist, which is consistent with the observational interpretation that the filament possesses a double-decker structure. The flux rope reaches the critical height of the torus instability during its initial relaxation, while the lower flux bundle remains in stable equilibrium. The eruption terminates when the flux rope reaches a dome-shaped quasi-separatrix layer that is reminiscent of a magnetic fan surface, although no magnetic null is found. The flux rope is destroyed by reconnection with the confining overlying flux above the dome, transferring its twist in the process. Y1 - 2021 U6 - https://doi.org/10.3847/1538-4357/ac2ba1 SN - 0004-637X SN - 1538-4357 VL - 923 IS - 2 PB - Institute of Physics Publ. CY - London ER - TY - JOUR A1 - Pan, Hanya A1 - Liu, Rui A1 - Gou, Tingyu A1 - Kliem, Bernhard A1 - Su, Yingna A1 - Chen, Jun A1 - Wang, Yuming T1 - Pre-eruption splitting of the double-decker structure in a solar filament JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - Solar filaments often erupt partially. Although how they split remains elusive, the splitting process has the potential of revealing the filament structure and eruption mechanism. Here we investigate the pre-eruption splitting of an apparently single filament and its subsequent partial eruption on 2012 September 27. The evolution is characterized by three stages with distinct dynamics. During the quasi-static stage, the splitting proceeds gradually for about 1.5 hr, with the upper branch rising at a few kilometers per second and displaying swirling motions about its axis. During the precursor stage that lasts for about 10 minutes, the upper branch rises at tens of kilometers per second, with a pair of conjugated dimming regions starting to develop at its footpoints; with the swirling motions turning chaotic, the axis of the upper branch whips southward, which drives an arc-shaped extreme-ultraviolet front propagating in a similar direction. During the eruption stage, the upper branch erupts with the onset of a C3.7-class two-ribbon flare, while the lower branch remains stable. Judging from the well-separated footpoints of the upper branch from those of the lower one, we suggest that the pre-eruption filament processes a double-decker structure composed of two distinct flux bundles, whose formation is associated with gradual magnetic flux cancellations and converging photospheric flows around the polarity inversion line. KW - Solar filament eruptions KW - Solar active region magnetic fields KW - Solar KW - flares KW - Solar filaments Y1 - 2021 U6 - https://doi.org/10.3847/1538-4357/abda4e SN - 0004-637X SN - 1538-4357 VL - 909 IS - 1 PB - Institute of Physics Publ. CY - London ER - TY - JOUR A1 - Xue, Rui A1 - Liu, Ruo-Yu A1 - Wang, Xiang-Yu A1 - Yan, Huirong A1 - Böttcher, Markus T1 - On the minimum jet power of TeV BL Lac objects in the p-gamma model JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We study the requirement of the jet power in the conventional p-gamma models (photopion production and Bethe-Heitler pair production) for TeV BL Lac objects. We select a sample of TeV BL Lac objects whose spectral energy distributions are difficult to explain by the one-zone leptonic model. Based on the relation between the p-gamma interaction efficiency and the opacity of gamma gamma absorption, we find that the detection of TeV emission poses upper limits on the p-gamma interaction efficiencies in these sources and hence minimum jet powers can be derived accordingly. We find that the obtained minimum jet powers exceed the Eddington luminosity of the supermassive black holes (SMBHs). Implications for the accretion mode of the SMBHs in these BL Lac objects and the origin of their TeV emissions are discussed. KW - galaxies: active KW - galaxies: jets KW - radiation mechanisms: non-thermal Y1 - 2019 U6 - https://doi.org/10.3847/1538-4357/aaf720 SN - 0004-637X SN - 1538-4357 VL - 871 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Gou, Tingyu A1 - Liu, Rui A1 - Kliem, Bernhard A1 - Wang, Yuming A1 - Veronig, Astrid M. T1 - The birth of a coronal mass ejection JF - Science Advances N2 - The Sun’s atmosphere is frequently disrupted by coronal mass ejections (CMEs), coupled with flares and energetic particles. The coupling is usually attributed to magnetic reconnection at a vertical current sheet connecting the flare and CME, with the latter embedding a helical magnetic structure known as flux rope. However, both the origin of flux ropes and their nascent paths toward eruption remain elusive. Here, we present an observation of how a stellar-sized CME bubble evolves continuously from plasmoids, mini flux ropes that are barely resolved, within half an hour. The eruption initiates when plasmoids springing from a vertical current sheet merge into a leading plasmoid, which rises at increasing speeds and expands impulsively into the CME bubble, producing hard x-ray bursts simultaneously. This observation illuminates a complete CME evolutionary path capable of accommodating a wide variety of plasma phenomena by bridging the gap between microscale and macroscale dynamics. Y1 - 2019 U6 - https://doi.org/10.1126/sciadv.aau7004 SN - 2375-2548 VL - 5 IS - 3 PB - American Assoc. for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Liu, Ruo-Yu A1 - Wang, Kai A1 - Xue, Rui A1 - Taylor, Andrew M. A1 - Wang, Xiang-Yu A1 - Li, Zhuo A1 - Yan, Huirong T1 - Hadronuclear interpretation of a high-energy neutrino event coincident with a blazar flare JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - Although many high-energy neutrinos detected by the IceCube telescope are believed to have an extraterrestrial origin, their astrophysical sources remain a mystery. Recently, an unprecedented discovery of a high-energy muon neutrino event coincident with a multiwavelength flare from a blazar, TXS 0506 + 056, shed some light on the origin of the neutrinos. It is usually believed that a blazar is produced by a relativistic jet launched from an accreting supermassive black hole (SMBH). Here, we show that the high-energy neutrino event can be interpreted by the inelastic hadronuclear interactions between the accelerated cosmic-ray protons in the relativistic jet and the dense gas clouds in the vicinity of the SMBH. Such a scenario only requires a moderate proton power in the jet, which could be much smaller than that required in the conventional hadronic model which instead calls upon the photomeson process. Meanwhile, the flux of the multiwavelength flare from the optical to gamma-ray band can be well explained by invoking a second radiation zone in the jet at a larger distance to the SMBH. In our model, the neutrino emission lasts a shorter time than the multiwavelength flare, so the neutrino event is not necessarily correlated with the flare, but it is probably accompanied by a spectrum hardening above a few giga-electron-volt (GeV). Y1 - 2019 U6 - https://doi.org/10.1103/PhysRevD.99.063008 SN - 2470-0010 SN - 2470-0029 VL - 99 IS - 6 PB - American Physical Society CY - Melville ER - TY - JOUR A1 - Chen, Jun A1 - Liu, Rui A1 - Liu, Kai A1 - Awasthi, Arun Kumar A1 - Zhang, Peijin A1 - Wang, Yuming A1 - Kliem, Bernhard T1 - Extreme-ultraviolet late phase of solar flares JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - A second peak in the extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as the EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop system. Here we carry out a survey of 55 M-and-above GOES-class flares with ELP during 2010-2014. Based on the flare-ribbon morphology, these flares are categorized as circular-ribbon (19 events), two-ribbon (23 events), and complex-ribbon (13 events) flares. Among them, 22 events (40%) are associated with coronal mass ejections, while the rest are confined. An extreme ELP, with the late-phase peak exceeding the main-phase peak, is found in 48% of two-ribbon flares, 37% of circular-ribbon flares, and 31% of complex-ribbon flares, suggesting that additional heating is more likely present during ELP in two-ribbon than in circular-ribbon flares. Overall, cooling may be the dominant factor causing the delay of the ELP peak relative to the main-phase peak, because the loop system responsible for the ELP emission is generally larger than, and well separated from, that responsible for the main-phase emission. All but one of the circular-ribbon flares can be well explained by a composite "dome-plate" quasi-separatrix layer (QSL). Only half of these show a magnetic null point, with its fan and spine embedded in the dome and plate, respectively. The dome-plate QSL, therefore, is a general and robust structure characterizing circular-ribbon flares. Y1 - 2020 U6 - https://doi.org/10.3847/1538-4357/ab6def SN - 0004-637X SN - 1538-4357 VL - 890 IS - 2 PB - Institute of Physics Publ. CY - London ER - TY - JOUR A1 - Li, Yuanqing A1 - Chen, Li A1 - Nofal, Issam A1 - Chen, Mo A1 - Wang, Haibin A1 - Liu, Rui A1 - Chen, Qingyu A1 - Krstić, Miloš A1 - Shi, Shuting A1 - Guo, Gang A1 - Baeg, Sang H. A1 - Wen, Shi-Jie A1 - Wong, Richard T1 - Modeling and analysis of single-event transient sensitivity of a 65 nm clock tree JF - Microelectronics reliability N2 - The soft error rate (SER) due to heavy-ion irradiation of a clock tree is investigated in this paper. A method for clock tree SER prediction is developed, which employs a dedicated soft error analysis tool to characterize the single-event transient (SET) sensitivities of clock inverters and other commercial tools to calculate the SER through fault-injection simulations. A test circuit including a flip-flop chain and clock tree in a 65 nm CMOS technology is developed through the automatic ASIC design flow. This circuit is analyzed with the developed method to calculate its clock tree SER. In addition, this circuit is implemented in a 65 nm test chip and irradiated by heavy ions to measure its SER resulting from the SETs in the clock tree. The experimental and calculation results of this case study present good correlation, which verifies the effectiveness of the developed method. KW - Clock tree KW - Modeling KW - Single-event transient (SET) Y1 - 2018 U6 - https://doi.org/10.1016/j.microrel.2018.05.016 SN - 0026-2714 VL - 87 SP - 24 EP - 32 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Liu, Rui A1 - Kliem, Bernhard A1 - Titov, Viacheslav S. A1 - Chen, Jun A1 - Wang, Yuming A1 - Wang, Haimin A1 - Liu, Chang A1 - Xu, Yan A1 - Wiegelmann, Thomas T1 - STRUCTURE, STABILITY, AND EVOLUTION OF MAGNETIC FLUX ROPES FROM THE PERSPECTIVE OF MAGNETIC TWIST JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We investigate the evolution of NOAA Active Region (AR) 11817 during 2013 August 10–12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated with a magnetic flux rope (MFR) located along the major polarity inversion line, where shearing and converging photospheric flows are present. Aided by the nonlinear force-free field modeling, we identify the MFR through mapping magnetic connectivities and computing the twist number ${{ \mathcal T }}_{w}$ for each individual field line. The MFR is moderately twisted ($| {{ \mathcal T }}_{w}| \lt 2$) and has a well-defined boundary of high squashing factor Q. We found that the field line with the extremum $| {{ \mathcal T }}_{w}| $ is a reliable proxy of the rope axis, and that the MFR's peak $| {{ \mathcal T }}_{w}| $ temporarily increases within half an hour before each flare while it decreases after the flare peak for both confined and eruptive flares. This pre-flare increase in $| {{ \mathcal T }}_{w}| $ has little effect on the AR's free magnetic energy or any other parameters derived for the whole region, due to its moderate amount and the MFR's relatively small volume, while its decrease after flares is clearly associated with the stepwise decrease in the whole region's free magnetic energy due to the flare. We suggest that ${{ \mathcal T }}_{w}$ may serve as a useful parameter in forewarning the onset of eruption, and therefore, the consequent space weather effects. The helical kink instability is identified as the prime candidate onset mechanism for the considered flares. KW - coronal mass ejections (CMEs) KW - Sun: corona KW - Sun: filaments, pominences KW - Sun: flares KW - Sun: magnetic fields Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/818/2/148 SN - 0004-637X SN - 1538-4357 VL - 818 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Tu, Rui A1 - Wang, L. A1 - Liu, Z. T1 - Real time monitoring ground motion using GPS with real time corrections JF - Survey Review N2 - The high rate GPS velocity determination technology which is based on the broadcast ephemeris and epoch differenced model can retrieve displacement of ground motion with the precision of a few centimetres to decimetres in real time. Moreover, the precision of the recovered displacement can be improved if the un-modelled errors such as broadcast ephemeris residuals, atmospheric residuals, multipath effects and high frequency noise are tackled more accurately. In this paper, we propose a method to improve the precision of the recovered displacement by appropriately making use of reference station corrections. For the reference stations, the coordinates are highly constrained to extract the error corrections that are to be broadcast via a communication link to the rover. After correcting the rover’s observations, some errors such as ephemeris residuals and atmospheric residuals are effectively eliminated or at least reduced. This improves the accuracy of the observations and thus enhances the reliability of the velocity estimation. The displacement can be recovered by integrating the estimated velocity after de-trending using a linear trend that is caused by the un-corrected residuals. The series of validation results in the experiment have shown that the displacement of the simulated motion can be real time recovered with a precision of 1–2 cm, and is thus applicable for real time monitoring of the ground motion. KW - Real time KW - High rate GPS KW - Strong motion KW - Reference station KW - Rover station Y1 - 2016 U6 - https://doi.org/10.1179/1752270614Y.0000000141 SN - 0039-6265 SN - 1752-2706 VL - 48 SP - 79 EP - 85 PB - Wiley CY - Abingdon ER -