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Linearized waveform inversion for vertical transversely isotropic elastic media:Methodology and multi-parameter crosstalk analysis

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Petroleum Science 2024年第1期21卷 252-271页

作者： Ke Chen Lu Liu Li-Nan Xu Fei Hu Yuan Yang Jia-Hui Zuo Le-Le Zhang Yang Zhao National Key Laboratory of Petroleum Resources and Engineering Unconventional Petroleum Research InstituteChina University of Petroleum(Beijing)Beijing102249China Aramco Beijing Research Center Aramco AsiaBeijing100102China University of Lausanne LausanneCH-1015Switzerland Bureau of Geophysical Prospecting China National Petroleum CorporationZhuozhou 072750HebeiChina

Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon *** migration aims at obtaining structural images of subsurface geologic *** specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection *** the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface *** seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted *** there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic ***,seismic migration and inversion techniques assume an acoustic or isotropic elastic *** reservoirs such as shale and tight sand formation have notable anisotropic *** present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)*** is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference *** proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each *** derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state *** inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based *** have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy ***,the Thomsen parameter is the most difficult to *** also analyze the multi-parameter crosstalk using scattering radiation patte

关键词： Elastic Anisotropy Least-squares imaging Waveform inversion Computational geophysics

Primordial black holes and curvature perturbations from false vacuum islands

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 58-72页

作者： Rong-Gen Cai Yu-Shi Hao Shao-Jiang Wang School of Physical Science and Technology Ningbo UniversityNingbo 315211China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China asia Pacific Center for Theoretical Physics Pohang 37673Republic of Korea

Recently,much attention has been focused on the false vacuum islands that are flooded by an expanding ocean of true-vacuum bubbles slightly later than most of the other parts of the *** delayed decay regions will accumulate locally larger vacuum energy density by staying in the false vacuum longer than those already transited into the true vacuum.A false vacuum island with thus acquired density contrast of a super-horizon size will evolve locally from radiation dominance to vacuum dominance,creating a local baby Universe that can be regarded effectively as a local closed *** such density contrasts of super-horizon sizes can ever grow large enough to exceed the threshold of gravitational collapse,primordial black holes will form similar to those collapsing curvature perturbations on super-horizon scales induced by small-scale enhancements during *** not,such density contrasts can still induce curvature perturbations potentially observable *** this paper,we revisit and elaborate on the generations of primordial black holes and curvature perturbations from delayed-decayed false vacuum islands during asynchronous first-order phase transitions with fitting formulas convenient for future model-independent studies.

关键词： first-order phase transitions primordial black holes curvature perturbations

New Indonesian Leader Expected To Maintain Friendly China Policy

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China Report ASEAN 2024年第4期9卷 32-33页

作者： Yang Danzhi the institute of asia-Pacific and Global Strategy Chinese Academy of Social Sciences the institute of National Security of Renmin University of China

Indonesian Minister of Defence Prabowo Subianto won Indonesia’s presidential election in February *** hails from an elite family that has served in many high positions in *** served in important positions in the mili... 详细信息

关键词： elite positions Indonesia

COMRADES FOREVER--To Lam’s visit demonstrates that China remains Vietnam’s top foreign policy priority

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China Report ASEAN 2024年第8期9卷 30-31页

作者： Yang Danzhi the institute of asia-Pacific and Global Strategy under the Chinese Academy of Social Sciences the institute of National Security of Renmin University of China

On August 20,2024,General Secretary of the Communist Party of Vietnam(CPV)central Committee and Vietnamese President To Lam concluded his state visit to *** was the destination for Lam's first overseas visit after taking office as general secretary of the CPV central Committee,which clearly demonstrates that the heads of both countries attach importance to developing the bilateral relations and that Vietnam regards China as the strategic choice and top priority for its foreign policy.

关键词： policy Vietnam priority

Spatial distribution and potential ecological and health risks associated with heavy metals in the Ijero-Ekiti mining site,Nigeria

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Regional Sustainability 2024年第1期5卷 26-41页

作者： Johnson Adedeji OLUSOLA Adeyinka Oluyemi ATURAMU Olufunke ASAOLU Olusesan Sola OGUNLEYE Department of Geography and Planning Science Ekiti State UniversityAdo Ekiti360211Nigeria institute of Ecology and Environmental Studies Obafemi Awolowo UniversityIle IfeOsun State220101Nigeria Department of Geology(Climate Change and Paleobiology Group) Ekiti State UniversityAdo Ekiti360211Nigeria Environmental Natural Resources and Blue EconomyEurope and Central AsiaWorld Bank GroupWashington D.C.20433the USA

Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the ***,artisanal gold mining has potential negative and long-term effects on economy,environment,and *** study collected soil samples from 16 sample points including a control point to examine the pollution degrees and spatial distribution of heavy metals,as well as ecological and health risks associated with heavy metal pollution in the Ijero-Ekiti mining site,*** Information System(GIS)and remote sensing technologies were used to identify regions with high concentrations of heavy metals and assess the environmental impact of gold mining *** results show that the mean heavy metal concentrations of 16 soil pointa are 8.94(±5.97)mg/kg for As,0.18(±0.54)mg/kg for Cd,0.11(±1.06)mg/kg for Co,14.32(±3.43)mg/kg for Cr,6.89(±0.64)mg/kg for Cu,48.92(±11.77)mg/kg for Fe,135.81(±30.75)mg/kg for Mn,5.92(±0.96)mg/kg for Ni,5.72(±1.66)mg/kg for Pb,and 13.94(±1.38)mg/kg for *** study reveals that heavy metal concentration in soils follows the order of Mn>Fe>Cr>Zn>As>Cu>Ni>Pb>Co>*** analysis of soil samples indicates that 3 principal components(PCs)account for 70.008%of the total variance and there are strong positive correlations between various pairs of heavy *** total potential ecological risk index(309.599)in the study area is ***-carcinogenic risk suggests that there may be long-term health impacts on people who work in the mining areas due to chronic exposure to the *** on the study,the hazard index of carcinogenic health risks associated with heavy metals through ingestion is 520.00×10^(–4).Dermal contact from As and Cr also increases the risk of cancer,with the highest hazard index value of 18.40×10^(–4).The lowest exposure pathway,with the hazard index value of 0.68×10^(–4),indicates that the inhalation of heavy metals has a comparatively low risk of can

关键词： Artisanal gold mining Heavy metals Exposure pathway Potential ecological risk Geo-accumulation index Ijero-Ekiti mining site

Slowly rotating charges from Weyl double copy for Kerr black hole with Chern-Simons correction

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Communications in Theoretical Physics 2024年第8期76卷 139-146页

作者： Yi-Ran Liu Jing-Rui Zhang Yun-Long Zhang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100149China National Astronomy Observatories Chinese Academy of ScienceBeijing 100101China International Center for Theoretical Physics asia-Pacific Beijing/HangzhouChina

The Weyl double copy builds the relation between gauge theory and gravity theory, in particular the correspondence between gauge solutions and gravity solutions. In this paper, we obtain the slowly rotating charge solutions from the Weyl double copy for the Kerr black hole with small Chern-Simons correction. Based on the Weyl double copy relation, for the Petrov type D solution in Chern-Simons modified gravity, we find the additional correction to the electromagnetic field strength tensor of the rotating charge. For the Petrov type I solution, we find that the additional electromagnetic field strength tensors have external sources, while the total sources vanish at the leading order.

关键词： Chern-Simons modified gravity Weyl double copy Kerr black hole

Accelerated rise in wildfire carbon emissions from Arctic continuous permafrost

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Science Bulletin 2024年第15期69卷 2430-2438页

作者： Xingru Zhu Gensuo Jia Xiyan Xu Key Laboratory of Regional Climate-Environment for Temperate East asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Wildfires over permafrost put perennially frozen carbon at ***,wildfire emissions from biomass burning over the diverse range of permafrost regions and their share in global wildfire emissions have not been *** results showed a dramatic increase in wildfire carbon emissions from permafrost regions over the period 1997–*** share of permafrost in global wildfire CO_(2) emissions increased from 2.42%in 1997 to 20.86%in *** wildfire emissions from continuous permafrost region is the single largest contributor to increased emissions in northern permafrost ***-induced emissions from 2019 to 2021 alone accounted for approximately 40%of the 25-year total CO_(2) emissions from continuous permafrost *** rise in wildfire emissions from continuous permafrost regions is explained by desiccation within a 5–10 cm soil depth,where wildfires combust belowground *** findings highlight the acceleration of fire-induced carbon emissions from continuous permafrost regions,which disturb the organic carbon stock and accelerate the positive feedback between permafrost degradation and climate warming,thus stimulating permafrost towards a climatic tipping point.

关键词： Wildfire Permafrost Carbon Fuel moisture CO_(2) Continuous permafrost

Supermassive black holes triggered by QCD axion bubbles

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Communications in Theoretical Physics 2024年第5期76卷 134-139页

作者： Hai-Jun Li Ying-Quan Peng Wei Chao Yu-Feng Zhou Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China International Centre for Theoretical Physics asia-Pacific Beijing/HangzhouChina

Supermassive black holes(SMBHs)are ubiquitous in the center of galaxies,although the origin of their massive seeds is still *** this paper,we investigate the formation of SMBHs from the quantum chromodynamics(QCD)axion *** this case,primordial black holes(PBHs)are considered as the seeds of SMBHs,which are generated from the QCD axion bubbles due to an explicit Peccei–Quinn(PQ)symmetry breaking after *** QCD axion bubbles are formed when the QCD axion starts to oscillate during the QCD phase *** consider a general case in which the axion bubbles are formed with the bubble effective angle θ_(eff)∈(0,π],leading to the minimum PBH mass∼■(10^(4)−10^(7))M⊙for the axion decay constant f_(a)∼■(10^(16))*** PBHs at this mass region may account for the seeds of SMBHs.

关键词： supermassive black holes primordial black holes quantum chromodynamics axion

Developing an atmospheric aging evaluation model of acrylic coatings:A semi-supervised machine learning algorithm

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1617-1627页

作者： Yiran Li Zhongheng Fu Xiangyang Yu Zhihui Jin Haiyan Gong Lingwei Ma Xiaogang Li Dawei Zhang Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China National Materials Corrosion and Protection Data Center University of Science and Technology BeijingBeijing 100083China BRI Southeast asia Network for Corrosion and Protection(MOE) Shunde Innovation School of University of Science and Technology BeijingFoshan 528399China

To study the atmospheric aging of acrylic coatings,a two-year aging exposure experiment was conducted in 13 representative climatic environments in *** atmospheric aging evaluation model of acrylic coatings was developed based on aging data including11 environmental factors from 567 cities.A hybrid method of random forest and Spearman correlation analysis was used to reduce the redundancy and multicollinearity of the data set by dimensionality reduction.A semi-supervised collaborative trained regression model was developed with the environmental factors as input and the low-frequency impedance modulus values of the electrochemical impedance spectra of acrylic coatings in 3.5wt%NaCl solution as *** model improves accuracy compared to supervised learning algorithms model(support vector machines model).The model provides a new method for the rapid evaluation of the aging performance of acrylic coatings,and may also serve as a reference to evaluate the aging performance of other organic coatings.

关键词： acrylic coatings coatings aging atmospheric environment machine learning