中国科学院机构知识库网格系统: 检索

STEP AP 242 Managed Model-based 3D Engineering: An Application Towards the Automation of Fixture Planning 期刊论文 OAI收割
International Journal of Automation and Computing, 2021, 卷号: 18, 期号: 5, 页码: 731-746
作者: Remil George Thomas; Deepak Lawrence K.; Manu R.

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Standard for the exchange of product model data (STEP) application protocol (AP) 242 product manufacturing information computer-aided fixture design computer aided design (CAD)/computer aided manufacturing (CAM), automation computer integrated manufacturing 3D surface roughness

Understanding the impacts of 'Grain for Green' land management practice on land greening dynamics over the Loess Plateau of China 期刊论文 OAI收割
LAND USE POLICY, 2020, 卷号: 99, 页码: 11
作者: Liu, Zhengjia; Wang, Jieyong; Wang, Xiaoyue

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收藏 | 浏览/下载：24/0 | 提交时间：2021/03/15

The 'Grain for Green' practice GIMMS3g NDVI Spatial residual analysis The TPRC-based NDVI model The Loess Plateau

Understanding the impacts of 'Grain for Green' land management practice on land greening dynamics over the Loess Plateau of China 期刊论文 OAI收割
LAND USE POLICY, 2020, 卷号: 99, 页码: 11
作者: Liu, Zhengjia; Wang, Jieyong; Wang, Xiaoyue; Wang, Yongsheng

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The 'Grain for Green' practice GIMMS3g NDVI Spatial residual analysis The TPRC-based NDVI model The Loess Plateau

The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition 期刊论文 OAI收割
Monthly Notices of the Royal Astronomical Society, 2020, 卷号: 494, 页码: 1865-1870
作者: HXMT

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stars: magnetic field stars: neutron pulsars: general Astrophysics - High Energy Astrophysical Phenomena Abstract: In 2011 December, PSR B054-69 experienced a spin-down rate transition (SRT), after which the spin-down power of the pulsar increased by $\sim 36{{\ \rm per\ cent}}$. About 1000 d after the SRT, the X-ray luminosity of the associated pulsar wind nebula (PWN) was found to brighten by $32\pm 8{{\ \rm per\ cent}}$. After the SRT, the braking index n of PSR B0540-69 changes from n = 2.12 to 0.03 and then keeps this value for about five years before rising to n = 0.9 in the following years. We find that most of the current models have difficulties in explaining the measured braking index. One exceptive model of the braking index evolution is the increasing dipole magnetic field of PSR B0540-69. We suggest that the field increase may result from some instabilities within the pulsar core that enhance the poloidal component at the price of toroidal component of the magnetic field. The increasing dipole magnetic field will result in the X-ray brightening of the PWN. We fit the PWN X-ray light curve by two models: one assumes a constant magnetic field within the PWN during the brightening and the other assumes an enhanced magnetic field proportional to the energy density of the PWN. It appears that the two models fit the data well, though the later model seems to fit the data a bit better. This provides marginal observational evidence that magnetic field in the PWN is generated by the termination shock. Future high-quality and high-cadence data are required to draw a solid conclusion.

Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文 OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者: HXMT

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Insight-HXMT Geant4 simulation Background observation Astrophysics - Instrumentation and Methods for Astrophysics Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.

GRB 200415A: A Short Gamma-Ray Burst from a Magnetar Giant Flare? 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 899, 页码: 106
作者: HXMT

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Gamma-ray bursts Soft gamma-ray repeaters Magnetars Gamma-ray transient sources 629 1441 992 1853 Astrophysics - High Energy Astrophysical Phenomena Abstract: The giant flares of soft gamma-ray repeaters (SGRs) have long been proposed to contribute to at least a subsample of the observed short gamma-ray bursts (GRBs). In this paper, we perform a comprehensive analysis of the high-energy data of the recent bright short GRB 200415A, which was located close to the Sculptor galaxy. Our results suggest that a magnetar giant flare provides the most natural explanation for most observational properties of GRB 200415A, including its location, temporal and spectral features, energy, statistical correlations, and high-energy emissions. On the other hand, the compact star merger GRB model is found to have difficulty reproducing such an event in a nearby distance. Future detections and follow-up observations of similar events are essential to firmly establish the connection between SGR giant flares and a subsample of nearby short GRBs.

A New Set of Parameters of High-Mass X-ray Binaries Found with their Cyclotron Lines 期刊论文 OAI收割
arXiv e-prints, 2018
作者: Zhang, Chengmin; Taani, Ali; Chaty, Sylvain; Karino, Shigeyuki; Song, Liming

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Astrophysics - High Energy Astrophysical Phenomena Abstract: We have derived new physical quantities for several High-Mass X-ray Binaries (HMXBs) with supergiant (SG) companions through their cyclotron lines. The parameters are: the terminal velocity of the wind, the mass loss rate of the donor, the effective temperature and the magnetic fields. These parameters influence significantly the improvement of the model of accretion. In spite of the variety of their observational properties, the corresponding magnetic field is around B ~ 10^12 G. This result can be constrained by the effects on stellar evolution. In addition, we have performed a segmentation in the parameter space of donors intended for several SG-HMXB listed in our sample set. The parameter space can be categorized into five regimes depending on the possibility of disk formation associated with accretion from the stellar wind. This can give a quantitative clarification of the observed variability and the properties of these objects. We show that, when these systems come into the direct accretion region, systems with corresponding parameters can emit X-rays.

STEP-based Feature Recognition System for B-spline Surface Features 期刊论文 OAI收割
International Journal of Automation and Computing, 2018, 卷号: 15, 期号: 4, 页码: 500-512
作者: Bitla Venu; Venkateswara Rao Komma; Deepanshu Srivastava

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Feature recognition 3D computer aided design (CAD) model geometrical information standard for the exchange of product model data (STEP) AP203 Java standard data access interface (JSDAI).

On the time evolution of brightness, volume and height of a coronal source in an M-class flare 期刊论文 OAI收割
ASTROPHYSICS AND SPACE SCIENCE, 2017, 卷号: 362, 期号: 6, 页码: 10
作者: Firoz, Kazi A.; Gan, W. Q.; Li, Y. P.; Rodriguez-Pacheco, J.; Su, Y.

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Solar flares Area/volume of the flare Volume and mean intensity Heights of the coronal sources Total Thermal electrons in high-temperature plasma in the corona contribution into the flare process Adiabatic expansion Theoretical model for thermal source RHESSI X-ray GOES X-ray SDO/AIA images Spatial and temporal evolution of the coronal source RHESSI image reconstruction algorithm

Correlations between neutrons and protons near the Fermi surface and Q(alpha) of superheavy nuclei 期刊论文 OAI收割
PHYSICAL REVIEW C, 2016, 卷号: 93, 期号: 1, 页码: 14302
作者: Wang, N; Liu, M; Wu, XZ; Meng, J; Wang, N (reprint author), Guangxi Normal Univ, Dept Phys, Guilin 541004, Peoples R China.

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The Shell Corrections And Shell Gaps In Nuclei Are Systematically Studied With The Latest Weizsacker-skyrme (Ws4) Mass Model. We Find That Most Of Asymmetric Nuclei With (Sub) Shell Closures Locate Along The Shell Stability Line (Ssl) n=1.37z+13.5 Which Might Be Due To a Strong Correlation Between Neutrons And proTons Near The Fermi Surface. The Double Magicity Of Nuclei Si-46 And Ni-78 Is Predicted According To The Corresponding Shell Gaps Shell Corrections And Nuclear Deformations. The Unmeasured Superheavy Nuclei (296)118 And (298)120 With Relatively Large Shell Gaps And Shell Corrections Also Locate Along The Ssl Whereas The Traditional Magic Nucleus (298)F1 Evidently Deviates From The Line. The Alpha-decay Energies Of Superheavy Nuclei With Z=113-126 Are Simultaneously Investigated By Using The Ws4 Model togeTher With The Radial Basis Function Corrections. For Superheavy Nuclei With Large Shell Corrections The Smallest Alpha-decay Energy For Elements Z=116 117 And 118 In Their Isotope chaIns LocAtes At N=178 rAther Than 184.