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Assessment of International GNSS Service Global Ionosphere Map products over China region based on measurements from the Crustal Movement Observation Network of China

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earth and Planetary Physics 2024年第2期8卷 400-407页

作者： Jin Hu HaiBing Ruan FuQing Huang ShengYang Gu XianKang Dou institute of space Weather Nanjing University of Information Science and TechnologyNanjing 210044China State Key Laboratory of space Weather Chinese Academy of Sciences(CAS)Beijing 100190China School of Electronic information Wuhan UniversityWuhan 430072China Wuxi Research institute Nanjing University of Information Science and TechnologyWuxi Jiangsu 214000China CAS Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China

The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical *** the credibility of GIM products in data-sparse regions is of paramount *** this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in *** indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM *** revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error *** results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.

关键词： International GNSS Service(IGS)Global Ionosphere Maps(GIM) Crustal Movement Observation Network of China(CMONOC) total electron content(TEC) data assessment

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Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1192-1201页

作者： Yu Feng Ke Gao Suzanne Lacasse Norwegian Geotechnical institute OsloNorway Department of earth and space sciences Southern University of Science and TechnologyShenzhenChina

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste *** one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC ***,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC *** address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement ***,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC *** performed five case studies using OC test data made at a nuclear waste repository research site of *** results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

关键词： Overcoring stress measurement Uncertainty reduction Partial pooling Bayesian hierarchical model Nuclear waste repository

Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

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science China earth sciences 2024年第5期67卷 1687-1697页

作者： Feng HU Huajian YAO Houyun YU Zeyu LU Jieyi HOU Song LUO Zhigang SHAO Xiaofei CHEN School of earth and space sciences University of Science and Technology of ChinaHefei 230026China Mengcheng Geophysical National Field Scientific Observatory Hefei 230026China Department of earth and space science Southern University of Science and TechnologyShenzhen 518055China institute of earthquake Prediction China Earthquake AdministrationBeijing 100036China

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern *** is important to improve the understanding of seismic hazard assessments in areas near *** start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu *** fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake *** the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation *** findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake *** compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial *** the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip *** response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

关键词： Scenario earthquakes Self-similar stress Tanlu Fault Dynamic rupture Ground motion

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Solar energetic particles intensity variations associated with a tilted-dipole 3D corotating interaction region

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earth and Planetary Physics 2024年第5期8卷 797-810页

作者： YuJi Zhu Fang Shen Xi Luo Yang Wang BoFeng Tang State Key Laboratory of space Weather National Space Science Center Chinese Academy of Sciences Shandong institute of Advanced Technology (SDIAT) College of earth and Planetary sciences University of Chinese Academy of Sciences School of science Harbin Institute of Technology

The effect of a tilted-dipole three-dimensional corotating interaction region(CIR) on the transport and acceleration of solar energetic particles(SEPs) is *** this work,we discussed how the particle intensity longitudinal and radial dependence might be influenced by the background ***,we investigate how the spectral index distribution is modulated by the CIR structure We use the focused transport equation(FTE) to describe the propagation and acceleration of SEPs in a tilt-dipole 3D CIR,generated by the high-resolution 3D magnetohydrodynamic(MHD) *** forward stochastic differential method is used to solve the *** protons with theE～(-4.4)spectrum from 0.5 to 15 MeV are injected uniformly at the heliographic equator of 0.15 *** quantities are extracted along each interplanetary magnetic field(IMF) line to show the *** the tilted-dipole CIR background,if injected from the solar equator at the inner boundary,particles in the slow flow are transported to higher latitudes due to the extension of the IMF lines to higher *** longitudinal patterns of the particles are dominated by the density of IMF *** focusing effect modulates the longitudinal variation of the particle intensity and gives rise to new longitudinal intensity *** adiabatic effect largely increases the intensity fluctuation along the *** structure of the solar wind can also lead to the difference of the index α in the empirical functionI＿(max)=kR～(-α),describing the radial variation of peak intensity according to our *** the influence of the CIR structure,the index α varies from 1.9 to 3.4 at 0.3-1.0 *** variation of the solar wind speed should be considered when estimating the radial dependence of the SEP peak *** spectra indices rise near the CIR boundaries and drop near the stream interface(SI).The adiabatic effect makes the spatial variability of the spectral index *** spectral index could be sim

关键词： solar energetic particle (SEP) corotating interaction regions (CIR) magnetohydrodynamic (MHD)

Improving the spaceborne GNSS-R altimetric precision based on the novel multilayer feedforward neural network weighted joint prediction model

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Defence Technology（防务技术） 2024年第2期32卷 271-284页

作者： Yiwen Zhang Wei Zheng Zongqiang Liu Qian Xuesen Laboratory of space Technology China Academy of Space TechnologyBeijing 100094China China Academy of Aerospace science and Innovation Beijing 100176China State Key Laboratory of space-Ground Integrated information Technology Beijing Institute of Satellite Information EngineeringBeijing 100194China

Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater *** present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically ***,GNSS-R satellite constellations that meet the global altimetry needs to be ***,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric ***,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is ***,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is ***,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.

关键词： GNSS-R satellite constellations Sea surface altimetric precision Underwater navigation Multilayer feedforward neural network

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Scientific objectives and payload configuration of the Chang'E-7 mission

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National science Review 2024年第2期11卷 285-300页

作者： Chi Wang Yingzhuo Jia Changbin Xue Yangting Lin Jianzhong Liu Xiaohui Fu Lin Xu Yun Huang Yufen Zhao Yigang Xu Rui Gao Yong Wei Yuhua Tang Dengyun Yu Yongliao Zou State Key Laboratory of space Weather National Space Science Center Chinese Academy of Sciences National space science Center Chinese Academy of Sciences institute of Geology and Geophysics Chinese Academy of Sciences institute of Geochemistry Chinese Academy of Sciences Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Institute of Space SciencesShandong University institute of Drug Discovery Technology Ningbo University State Key Laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences School of earth science and Engineering Sun Yat-sen University Lunar Exploration and space Engineering Center China Aerospace science and Technology Corporation

As the cornerstone mission of the fourth phase of the Chinese Lunar Exploration Program, Chang'E-7(CE-7) was officially approved, and implementation started in 2022, including a main probe and a communication relay satellite. The main probe, consisting of an orbiter, a lander, a rover and a mini-flying probe, is scheduled to be launched in 2026. The lander will land on Shackleton crater's illuminated rim near the lunar south pole, along with the rover and mini-flying probe. The relay satellite(named Queqiao-2) will be launched in February 2024 as an independent mission to support relay communication during scientific exploration undertaken by Chang'E-4, the upcoming Chang'E-6 in 2024 and subsequent lunar *** CE-7 mission is mainly aimed at scientific and resource exploration of the lunar south pole. We present CE-7's scientific objectives, the scientific payloads configuration and the main functions for each scientific payload with its key technical specifications.

关键词： Chang’ E-7 scientific objectives scientific payloads

Assessing the performance of magnetopause models based on THEMIS data

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earth and Planetary Physics 2024年第5期8卷 776-786页

作者： Yang Lin JianYong Lu BaoHang Qu Xi Wang institute of space Weather School of Atmospheric PhysicsNanjing University of Information Science & Technology

The magnetopause is the boundary between the earth's magnetic field and the interplanetary magnetic field（IMF）,located where the supersonic solar wind and magnetospheric pressure are in *** empirical models and global magnetohydrodynamic simulations have been used to define the magnetopause,each of these has *** this work,we use15 years of magnetopause crossing data from the THEMIS（Time History of Events and Macroscale Interactions during Substorms）spacecraft and their corresponding solar wind parameters to investigate under which solar wind conditions these models predict more *** analyze the pattern of large errors in the extensively used magnetopause model and show the specific solar wind parameters,such as components of the IMF,density,velocity,temperature,and others that produce these *** is shown that（1） the model error increases notably with increasing solar wind velocity,decreasing proton density,and increasing temperature;（2） when the cone angle becomes smaller or|Bx|is larger,the Shue98 model errors increase,which might be caused by the magnetic reconnection on the dayside magnetopause;（3） when|By|is large,the error of the model is large,which may be caused by the east–west asymmetry of the magnetopause due to magnetic reconnection;（4） when Bzis southward,the error of the model is larger;and（5） the error is larger for positive dipole tilt than for negative dipole tilt and increases with an increasing dipole tilt ***,the global simulation model b Liu ZQ et al.（2015） shows a substantial improvement in prediction accuracy when IMF Bx,By,or the dipole tilt cannot be *** result can help us choose a more accurate model for forecasting the magnetopause under different solar wind conditions.

关键词： magnetopause empirical model global magnetohydrodynamic simulation THEMIS solar wind parameters

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Petroleum science 2024年第4期21卷 2383-2392页

作者： Li-Ming Zhao Cai-Ping Lu Yang Liu Chao-Chao Li School of Mines China University of Mining and Technology Henan institute of Geophysical space information

The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D) poroelastic model and the layered White model were investigated. This investigation was conducted under the assumption that the rock was homogenous and isotropic at the mesoscopic scale. For the inherent mechanism, both models resulted from quasi-static flow in a slow P-wave diffusion mode, and the differences between them originated from saturated fluids and boundary conditions. On the other hand, for the characteristic frequencies of the models, the characteristic frequency of the 1D poroelastic model was first modified because the elastic constant and formula for calculating it were misused and then compared to that of the layered White model. Both of them moved towards higher frequencies with increasing permeability and decreasing viscosity and diffusion length. The differences between them were due to the diffusion length. The diffusion length for the 1D poroelastic model was determined by the sample length, whereas that for the layered White model was determined by the length of the representative elementary volume(REV). Subsequently, a numerical example was presented to demonstrate the similarities and differences between the models. Finally, published experimental data were interpreted using the 1D poroelastic model combined with the Cole-Cole *** prediction of the combined model was in good agreement with the experimental data, thereby validating the effectiveness of the 1D poroelastic model. Furthermore, the modified characteristic frequency in our study was much closer to the experimental data than the previous prediction, validating the effectiveness of our modification of the characteristic frequency of the 1D poroelastic model. The investigation provided insight into the internal relationship between wave-induced fluid flow(WIFF)models at macroscopic and mesoscopic scales and can aid in a better understanding of the elastic modulus d

关键词： 1D poroelastic model Layered White model Quasi-static flow Slow P-wave diffusion Characteristic frequency Diffusion length

A novel(Sm0.2Eu0.2Gd0.2Ho0.2Yb0.2)CrO3 high-entropy ceramic nanofiber as a negative temperature coefficient thermistor

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Journal of Rare earths 2024年第10期42卷 1937-1942页

作者： Weijun Zhao Meng Zhang Liyan Xue Kaixian Wang Fan Yang Jiuping Zhong Heng Chen School of Materials Sun Yat-sen University Xiamen institute of Rare earth Materials Haixi InstituteChinese Academy of Sciences Xiamen Key Laboratory of Rare earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of Sciences Fujian science & Technology Innovation Laboratory for Optoelectronic information of China Advanced Energy science and Technology Guangdong Laboratory Sichuan Jcc Rare earth Metals New Material Co. Ltd.

The electrical properties of high-entropy ceramics（HECs） have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy *** high-entropy(Sm0.2Eu0.2Gd0.2Ho0.2Yb0.2)CrO3（HE-RECrO3） nanofibers were prepared by electro *** work demonstrates that HE-RECrO3nanofibe rs were successfully synthesized at a low temperature（800℃）,which is approximately 400 ℃ lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction *** resistivity of HE-RECrO3nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of *** B25/50value of the HERECrO3nanofibers reaches 4072 *** conclusion,HE-RECrO3nanofibers are expected to be potential candidates for negative-temperature-coefficient（NTC） thermistors.

关键词： Ceramic fiber materials High-entropy ceramics Negative temperature coefficient thermistors Rare earths