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  • IOP Publishing  (39)
  • Liu, Chao  (39)
  • 2020-2024  (39)
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  • IOP Publishing  (39)
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  • 2020-2024  (39)
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  • 1
    Online Resource
    Online Resource
    LAMOST Time-Domain survey: first results of four K2 plates
    IOP Publishing ; 2021
    In:  Research in Astronomy and Astrophysics Vol. 21, No. 11 ( 2021-12-01), p. 292-
    Details
    In: Research in Astronomy and Astrophysics, IOP Publishing, Vol. 21, No. 11 ( 2021-12-01), p. 292-
    Abstract: From Oct. 2019 to Apr. 2020, LAMOST performed a time-domain (TD) spectroscopic survey of four K2 plates with both low- and medium-resolution observations. The low-resolution spectroscopic survey acquired 282 exposures ( ≈ 46.6 h) over 25 nights, yielding a total of about 767 000 spectra, and the medium-resolution survey took 177 exposures ( ≈ 49.1 h) over 27 nights, collecting about 478 000 spectra. More than 70%/50% of low-resolution/medium-resolution spectra have signal-to-noise ratio higher than 10. We determine stellar parameters (e.g., T eff , log  g , [Fe/H]) and radial velocity (RV) with different methods, including LASP, DD-Payne and SLAM. In general, these parameter estimations from different methods show good agreement, and the stellar parameter values are consistent with those of APOGEE. We use the Gaia DR2 RV values to calculate a median RV zero point (RVZP) for each spectrograph exposure by exposure, and the RVZP-corrected RVs agree well with the APOGEE data. The stellar evolutionary and spectroscopic masses are estimated based on the stellar parameters, multi-band magnitudes, distances and extinction values. Finally, we construct a binary catalog including about 2700 candidates by analyzing their light curves, fitting the RV data, calculating the binarity parameters from medium-resolution spectra and cross-matching the spatially resolved binary catalog from Gaia EDR3. The LAMOST TD survey is expected to represent a breakthrough in various scientific topics, such as binary systems, stellar activity, stellar pulsation, etc.
    Type of Medium: Online Resource
    ISSN: 1674-4527
    URL: Article
    DOI: 10.1088/1674-4527/21/11/292
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2511247-8
    SSG: 6,25
    SSG: 16,12
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    Online Resource
  • 2
    Online Resource
    Online Resource
    LAMOST medium-resolution spectroscopic survey of binarity and exotic star (LAMOST-MRS-B): Observation strategy and target selection
    IOP Publishing ; 2023
    In:  Chinese Physics B Vol. 32, No. 1 ( 2023-01-01), p. 019501-
    Details
    In: Chinese Physics B, IOP Publishing, Vol. 32, No. 1 ( 2023-01-01), p. 019501-
    Abstract: LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution ( R ∼ 7500) spectroscopic survey. It aims at studying the statistical properties (e.g., binary fraction, orbital period distribution, mass ratio distribution) of binary stars and exotic stars. We intend to observe about 30000 stars (10 mag ≤ G 〈 14.5 mag) with at least 10 visits in five years. We first planned to observe 25 plates around the galactic plane in 2018. Then the plates were reduced to 12 in 2019 because of the limitation of observation. At the same time, two new plates located at the high galactic latitude were added to explore binary properties influenced by the different environments. In this survey project, we set the identified exotic and low-metallicity stars with the highest observation priorities. For the rest of the selected stars, we gave the higher priority to the relatively brighter stars in order to obtain high quality spectra as many as possible. Spectra of 49129 stars have been obtained in LAMOST-MRS-B field and released in DR8, of which 28828 and 3375 stars have been visited more than twice and ten times with SNR ≥ 10, respectively. Most of the sources are B-, A-, and F-type stars with –0.6 〈 [Fe/H] 〈 0.4 dex. We also obtain 347 identified variable and exotic stars and about 250 stars with [Fe/H] 〈 –1 dex. We measure radial velocities (RVs) by using 892233 spectra of the stars. The uncertainties of RV achieve about 1 km ⋅ s −1 and 10 km ⋅ s −1 for 95% of late- and early-type stars, respectively. The datasets presented in this paper are available at http://www.doi.org/10.57760/sciencedb.j00113.00035 .
    Type of Medium: Online Resource
    ISSN: 1674-1056
    URL: Article
    DOI: 10.1088/1674-1056/ac9362
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 2412147-2
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    Online Resource
  • 3
    Online Resource
    Online Resource
    On the radial velocity calibrations in the LAMOST medium-resolution spectroscopic survey of nebulae
    IOP Publishing ; 2021
    In:  Research in Astronomy and Astrophysics Vol. 21, No. 3 ( 2021-04-01), p. 051-
    Details
    In: Research in Astronomy and Astrophysics, IOP Publishing, Vol. 21, No. 3 ( 2021-04-01), p. 051-
    Abstract: Accurate radial velocity determinations of optical emission lines (i.e., [N ii ] λλ 6548, 6584, H α and [S ii ] λλ 6717, 6731) are very important for investigating the kinematic and dynamic properties of nebulae. The second stage survey program of Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) has started a sub-survey of nebulae (MRS-N) which will spectroscopically observe the optical emission lines of a large sample of nebulae near the Galactic plane. Until now, 15 MRS-N plates have been observed from September 2017 to June 2019. Based on fitting the sky emission lines in the red band spectra of MRS-N, we investigate the precision of wavelength calibration and find there are systematic deviations of radial velocities (RVs) from ∼ 0.2 to 4 km s −1 for different plates. Especially for the plates obtained in March 2018, the systematic deviations of RVs can be as large as ∼ 4 km s −1 , which then go down to ∼ 0.2 – 0.5 km s −1 at the end of 2018 and January 2019. An RV calibration function is proposed for these MRS-N plates, which can simultaneously and successfully calibrate the systematic deviations and improve the precision of RVs.
    Type of Medium: Online Resource
    ISSN: 1674-4527
    URL: Article
    DOI: 10.1088/1674-4527/21/3/51
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2511247-8
    SSG: 6,25
    SSG: 16,12
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Research on distributed photovoltaic power generation prediction based on grey model for energy Internet of city
    IOP Publishing ; 2020
    In:  IOP Conference Series: Earth and Environmental Science Vol. 440, No. 3 ( 2020-02-01), p. 032011-
    Details
    In: IOP Conference Series: Earth and Environmental Science, IOP Publishing, Vol. 440, No. 3 ( 2020-02-01), p. 032011-
    Abstract: Power load forecasting is one of the basic tasks of power system dispatching coordination and rational arrangement of energy production. Reasonable power load forecasting can ensure safe, continuous and stable energy supply, and provide reasonable guarantee for the safe and economic operation of power system. Based on Beijing’s new energy and renewable energy online monitoring system, this paper collects power generation data, environmental data and equipment working condition data, and uses gray model prediction method to predict the load of XXXXX photovoltaic power station, and obtain more accurate power load data, which is complex fluctuation. The photovoltaic power generation project provides the basis for post-generation planning.
    Type of Medium: Online Resource
    ISSN: 1755-1307 , 1755-1315
    URL: Article
    DOI: 10.1088/1755-1315/440/3/032011
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 2434538-6
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Focusing on the relationship between the precipitated phases and the pitting corrosion of ZL101A aluminum alloy
    IOP Publishing ; 2021
    In:  Surface Topography: Metrology and Properties Vol. 9, No. 4 ( 2021-12-01), p. 045047-
    Details
    In: Surface Topography: Metrology and Properties, IOP Publishing, Vol. 9, No. 4 ( 2021-12-01), p. 045047-
    Abstract: The pitting corrosion behavior of ZL101A aluminum alloy in simulated marine environment was investigated for guiding the composition design. The Volta potential of the precipitated phases was mainly characterized via the in situ SKPFM technique. The obtained results indicated that the precipitated phases of ZL101A were composed of Al–Si phase, Si–Mg–Fe phase and Si-rich/Al-poor phase, accelerating the formation of corrosion pits during immersion test. Both Al–Si phase and Si–Mg–Fe phase accelerated the corrosion process through the self-dissolution and the galvanic effect, respectively, which can be contributed to the high corrosion sensitivity of the two phases. Si-rich/Al-poor phase presented high corrosion resistance, which should be related to the deficiency of impure elements such as Mg and Fe.
    Type of Medium: Online Resource
    ISSN: 2051-672X
    URL: Article
    DOI: 10.1088/2051-672X/ac4344
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2739097-4
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  • 6
    Online Resource
    Online Resource
    Exploring the spectral information content in the LAMOST medium-resolution survey (MRS)
    IOP Publishing ; 2020
    In:  Research in Astronomy and Astrophysics Vol. 20, No. 4 ( 2020-04-01), p. 051-
    Details
    In: Research in Astronomy and Astrophysics, IOP Publishing, Vol. 20, No. 4 ( 2020-04-01), p. 051-
    Abstract: Although high-resolution stellar spectra allow us to derive precise stellar labels (effective temperature, metallicity, surface gravity, elemental abundances, etc.) based on resolved atomic lines and molecular bands, low-resolution spectra have been proved to be competitive in determiningmany stellar labels at comparable precision. It is useful to consider the spectral information content when assessing the capability of a stellar spectrum in deriving precise stellar labels. In this work, we quantify the information content brought by the LAMOST-II medium-resolution spectroscopic survey (MRS) using the gradient spectra as well as the coefficients-of-dependence (CODs). In general, the wavelength coverage of the MRS well constrains the stellar labels but the sensitivities of different stellar labels vary with spectral types and metallicity of the stars of interest. Consequently, this affects the performance of the stellar label determination from the MRS spectra. By applying the SLAM method to the synthetic spectra which mimic the MRS data, we find that the precision of the fundamental stellar parameters T eff , log g and [M/H] are better when combining both the blue and red bands of the MRS. This is especially important for warm stars because the H α line located in the red part plays a more important role in determining the effective temperature for warm stars. With blue and red parts together, we are able to reach similar performance to the low-resolution spectra except for warm stars. However, at [M/H] ∼ −2.0 dex, the uncertainties of fundamental stellar labels estimated from MRS are substantially larger than that from low-resolution spectra. We also tested the uncertainties of T eff , log g and [M/H] From MRS data induced from the radial velocity mismatch and find that a mismatch of about 1 km s −1 , which is typical for LAMOST MRS data, would not significantly affect the stellar label estimates. Finally, reference precision limits are calculated using synthetic gradient spectra, according to which we expect abundances of at least 17 elements to be measured precisely from MRS spectra.
    Type of Medium: Online Resource
    ISSN: 1674-4527
    URL: Article
    DOI: 10.1088/1674-4527/20/4/51
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 2511247-8
    SSG: 6,25
    SSG: 16,12
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  • 7
    Online Resource
    Online Resource
    Terahertz plasmonic sensing based on tunable multispectral plasmon-induced transparency and absorption in graphene metamaterials
    IOP Publishing ; 2021
    In:  Journal of Physics D: Applied Physics Vol. 54, No. 24 ( 2021-06-17), p. 245201-
    Details
    In: Journal of Physics D: Applied Physics, IOP Publishing, Vol. 54, No. 24 ( 2021-06-17), p. 245201-
    Abstract: Graphene surface plasmons have gained wide interest due to their promising applications in terahertz technology. In this paper, we propose an easily implemented monolayer graphene structure, and exploit its quadra resonance mode to achieve triple plasmon-induced transparency (PIT) and triple plasmon-induced absorption (PIA) effects. A uniform theoretical model with four resonators is introduced to elaborate the intrinsic coupling mechanism and examine the accuracy of simulated results. By altering the Fermi energy and the carrier mobility of the graphene, the proposed triple PIT (PIA) system exhibits a dynamically tunable property, and the absorption intensity can be controlled over a broadband frequency range. It is found that the absorption intensity of the triple PIA spectrum can be as high as 50% with four absorption bands, which is 20 times more than that of monolayer graphene. Besides, we further investigate the triple PIT system for terahertz plasmonic sensing applications, and it is shown that the highest sensitivity of 0.4 THz RIU −1 is reached. Thus, the triple PIT system we propose can be employed for multi-band light absorption and plasmonic optical sensing.
    Type of Medium: Online Resource
    ISSN: 0022-3727 , 1361-6463
    URL: Article
    DOI: 10.1088/1361-6463/abec0c
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 209221-9
    detail.hit.zdb_id: 1472948-9
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  • 8
    Online Resource
    Online Resource
    Plasmonic biosensor based on excellently absorbable adjustable plasmon-induced transparency in black phosphorus and graphene metamaterials
    IOP Publishing ; 2020
    In:  New Journal of Physics Vol. 22, No. 7 ( 2020-07-01), p. 073049-
    Details
    In: New Journal of Physics, IOP Publishing, Vol. 22, No. 7 ( 2020-07-01), p. 073049-
    Abstract: Both black phosphorus (BP) and graphene metamaterials support surface plasmon resonance that is very sensitive to the local change of dielectric properties in the system. We design a novel BP ribbons and graphene sheet hybrid structures based on tunable mid-infrared plasmon-induced transparency. The destructive interference of two excited state modes in the structure leads to a pronounced induced transparent window, and the excellent absorption of the two channels is obtained. The transmission characteristics of the hybrid structures are theoretical calculation, and the results are in good agreement with the numerical simulation curve. The dynamic adjustment function can be realized by adjusting the carrier density of BP and the Fermi level of graphene, and the excellent absorption performance not affected within the adjustment range. Moreover, we found that the optical phase is rapid flips at the plasmon resonance position. Therefore, a sensing medium layer is added on top of the structure to implement a high-sensitivity plasmonic biosensor. This work may provide potential applications to plasmonic devices based on two-dimensional metamaterial.
    Type of Medium: Online Resource
    ISSN: 1367-2630
    URL: Article
    DOI: 10.1088/1367-2630/ab9b58
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 1464444-7
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  • 9
    Online Resource
    Online Resource
    Application of direct energy balance control in Supercritical Unit Coordinated Control System
    IOP Publishing ; 2023
    In:  Journal of Physics: Conference Series Vol. 2503, No. 1 ( 2023-05-01), p. 012087-
    Details
    In: Journal of Physics: Conference Series, IOP Publishing, Vol. 2503, No. 1 ( 2023-05-01), p. 012087-
    Abstract: The direct energy balance control strategy is analyzed and combined with the characteristics of supercritical units. The direct energy balance strategy is reconstructed. The reconstructed direct energy balance signal is applied to the boiler master control feedforward in the coordinated control, taking a power plant’s coordinated control system as an example, t. Thus, it is applied to the control of supercritical units, which improves the regulation quality of the control system in a steady and dynamic state, and effectively solves the problems of large fluctuation of mainstream pressure, locked increase, and decrease of load command, frequent withdrawal of coordinated control and unqualified AGC index.
    Type of Medium: Online Resource
    ISSN: 1742-6588 , 1742-6596
    URL: Article
    DOI: 10.1088/1742-6596/2503/1/012087
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 2166409-2
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  • 10
    Online Resource
    Online Resource
    Dual-frequency on–off modulation and slow light analysis based on dual plasmon-induced transparency in terahertz patterned graphene metamaterial
    IOP Publishing ; 2020
    In:  New Journal of Physics Vol. 22, No. 10 ( 2020-10-01), p. 103030-
    Details
    In: New Journal of Physics, IOP Publishing, Vol. 22, No. 10 ( 2020-10-01), p. 103030-
    Abstract: A dual-frequency on–off modulator with considerable modulation depth (MD) and relatively low insertion loss (IL) is performed with patterned monolayer graphene metamaterial. Destructive interference in this structure gives rise to the dual plasmon-induced transparency (DPIT) phenomenon. The coupled mode theory, confirmed by simulated values, is comprehensively introduced to expound the physical mechanism of the DPIT effect. In addition, the influences of the Fermi level on the DPIT transmission spectrum and the carrier mobility of graphene on the on–off modulation are researched. It is found that the dual-frequency on–off modulator exhibits remarkable modulation performance on both switches and is easier to fabricate in operation than other multi-layer graphene-based modulators. In the ‘on 1 /off 1 ’ state, the MD and IL are 93%, 0.32 dB, respectively. In the ‘on 2 /off 2 ’ state, the MD and IL are 85%, 0.25 dB, separately. Moreover, the property of slow light reflected by the group index is analyzed. It exhibits that the group index of the proposed structure with multi-channel can reach 358. Thus, the proposed structure stretches the versatile applications in multi-function modulators and multi-channel slow light devices at the terahertz band.
    Type of Medium: Online Resource
    ISSN: 1367-2630
    URL: Article
    DOI: 10.1088/1367-2630/abbaea
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 1464444-7
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