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NON-EQUILIBRIUM SEGREGATION OF Si ON Al-0.35 wt-% Si ALLOY SURFACE

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 98-101页

作者： chen Niug yu zongsen university of science and technology beijing,beijing,china professor,Department of Materials Physics,university of science and technology beijing,beijing 100083,china beijing Univ of science and Technology Beijing China

Si segregation was observed in the vacancy condensation pits,formed by supersaturated vacancies beneath the oxidation layer of Al-0.35wt-％Si alloy,by optical microscopy,X- ray photoelectron spectroscopy and microhard... 详细信息

关键词： non-equilibrium segregation vacancy AI-Si alloy surface Si

Response characteristics of PWR primary circuit under SBLOCAs considering steam bypass discharging

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Nuclear science and Techniques 2024年第6期35卷 189-201页

作者： Shuai Yang Xiang-Bin Li yu-Sheng Liu Jia-ning Xu De-chen Zhang School of Nuclear science and Engineering North China Electric Power UniversityBeijing 102206China beijing Key Laboratory of Passive Safety technology for Nuclear Energy Beijing 102206China Nuclear and Radiation Safety Center MEPBeijing 100084China

Small-break superposed station blackout(SBO)accidents are the basic design accidents of nuclear power *** the condition of a small break in the cold leg,SBO further increases the severity of the accident,and the steam bypass discharg-ing system(GCT)in the second circuit can play an important role in guaranteeing core *** explore the influence of the GCT on the thermal-hydraulic characteristics of the primary circuit,RELAP5 software was used to establish a numerical model based on a typical pressurized water reactor nuclear power *** different small breaks in the cold-leg super-posed SBO were selected,and the impact of the GCT operation on the transient response characteristics of the primary and secondary circuit systems was *** results show that the GCT plays an indispensable role in core heat removal during an accident;otherwise,core safety cannot be *** GCT was used in conjunction with the primary safety injection system during the placement *** the break diameter was greater than a certain critical value,the core cooling rate could not be guaranteed to be less than 100 K/h;however,the core remained in a safe state.

关键词： Steam bypass discharging Pressurized water reactor SBLOCA Numerical simulation

Risk assessment of oil and gas investment environment in countries along the Belt and Road Initiative

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Petroleum science 2024年第2期21卷 1429-1443页

作者： Bao-Jun Tang Chang-Jing Ji yu-Xian Zheng Kang-ning Liu Yi-Fei Ma Jun-yu chen Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing100081China School of Management and Economics Beijing Institute of TechnologyBeijing100081China Collaborative Innovation Center of Electric Vehicles in beijing BeijingChina Sustainable Development Research Institute for Economy and Society of beijing BeijingChina Institute of Carbon Neutrality ShanghaiTech UniversityShanghai201210China

With the implementation of the Belt and Road Initiative, china is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for china's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.

关键词： Belt and Road Initiative Oil and Gas Investment Risk assessment

The pseudospectrum and spectrum(in)stability of quantum corrected Schwarzschild black hole

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science china(Physics,Mechanics & Astronomy) 2024年第10期67卷 55-75页

作者： Li-Ming Cao Jia-ning chen Liang-Bi Wu Libo Xie yu-Sen Zhou School of Fundamental Physics and Mathematical sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China Peng Huanwu Center for Fundamental Theory Hefei 230026China Interdisciplinary Center for Theoretical Study and Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

In this study,we investigate the pseudospectrum and spectrum(in)stability of quantum corrected Schwarzschild black ***,we use the hyperboloidal framework to cast the quasinormal mode(QNM)problem into an eigenvalue problem associated with a non-selfadjoint operator,and then the spectrum and pseudospectrum are ***,the invariant subspace method is exploited to improve the computational efficiency for *** investigation into the spectrum(in)stability entails two main *** the one hand,we calculate the spectra of the quantum corrected black hole,then by the means of the migration ratio,the impact of the quantum correction effect on the Schwarzschild black hole has been *** results indicate that the so-called“migration ratio instability”will occur for small black holes with small angular momentum number *** the eikonal limit,the migration ratios remain the same for each *** the other hand,we study the spectrum(in)stability of the quantum corrected black hole by directly adding some particular perturbations into the effective potential,where perturbations are located at the event horizon and null infinity,*** are two interesting observations under the same perturbation energy ***,perturbations at infinity are more capable of generating spectrum instability than those at the event ***,we find that the peak distribution can lead to the instability of QNM spectrum more efficiently than the average distribution.

关键词： quasinormal modes pseudospectrum hyperboloidal coordinate

Target Detection Algorithm in Foggy Scenes Based on Dual Subnets

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Computers, Materials & Continua 2024年第2期78卷 1915-1931页

作者： yuecheng yu Liming Cai Anqi ning Jinlong Shi Xudong chen Shixin Huang School of Computer science Jiangsu University of Science and TechnologyZhenjiang212100China Information Department China Merchants Heavy IndustryNantong226116China

Under the influence of air humidity,dust,aerosols,etc.,in real scenes,haze presents an uneven *** this way,the image quality and contrast will *** this case,It is difficult to detect the target in the image by the universal detection ***,a dual subnet based on multi-task collaborative training(DSMCT)is proposed in this ***,in the training phase,the Gated Context Aggregation Network(GCANet)is used as the supervisory network of YOLOX to promote the extraction of clean information in foggy *** the test phase,only the YOLOX branch needs to be activated to ensure the detection speed of the ***,the deformable convolution module is used to improve GCANet to enhance the model’s ability to capture details of non-homogeneous ***,the Coordinate Attention mechanism is introduced into the Vision Transformer and the backbone network of YOLOX is *** this way,the feature extraction ability of the network for deep-level information can be *** experimental results on artificial fog data set FOG_VOC and real fog data set RTTS show that the map value of DSMCT reached 86.56%and 62.39%,respectively,which was 2.27%and 4.41%higher than the current most advanced detection *** DSMCT network has high practicality and effectiveness for target detection in real foggy scenes.

关键词： Target detection fog target detection YOLOX twin network multi-task learning

The effect of seismic action on stability of saline soil subgrade in cold region based on isothermal stratification method

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Earthquake Research Advances 2024年第3期4卷 66-81页

作者： Jie cheng yu Zhang Ying Ma Xuerui chen ning An School of Traffic and Transportation Lanzhou Jiaotong UniversityLanzhou730070China Key Laboratory of Railway Industry of Plateau Railway Transportation Intelligent Management and Control Lanzhou Jiaotong UniversityLanzhou730070China Gansu Institute of Engineering Geology Lanzhou730030China

With the change of seasons, the shear strength of saline soil subgrade filler will change with the change of external temperature, which will aggravate the adverse effects of seismic on the subgrade. To explore the influence of seismic action on the stability of saline soil subgrade under the influence of temperature on the strength of saline soil subgrade filler, this paper first carried out saline soil shear tests at different temperatures to obtain the influence of temperature on the shear strength of saline soil. Then, the temperature field of the saline soil subgrade was simulated, and then based on the subgrade isothermal stratification model and FLAC3D, the displacement and acceleration amplification effects of seismic action on the shady slope, sunny slope and subgrade of saline soil subgrade in different months were analyzed. The following conclusions were finally drawn: under the action of seismic, In the process of the change of subgrade temperature of Qarhan-Golmud Expressway between 7.7°C and 27°C, the change of saline soil cohesion is the main factor affecting the stability of subgrade slope, and the maximum and minimum values of subgrade surface settlement appear in September and June of each year,respectively. In August, the differences of settlement between the shady slope and the sunny slope shoulder of the subgrade were the largest, and the acceleration of the shady slope and the sunny slope and the inside of the subgrade changed most significantly in the vertical direction. Special attention should be paid to the seismic early warning in the above key months;In the range from both sides of the shoulder to the centerline of the roadbed,the acceleration amplification effect starts to increase significantly from about 3m from the centerline of the roadbed to the centerline, so it is necessary to pay attention to the seismic design of this range.

关键词： Subgrade stability Saline soils Acceleration amplification effect Seismic design

An Opposition-Based Learning-Based Search Mechanism for Flying Foxes Optimization Algorithm

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Computers, Materials & Continua 2024年第6期79卷 5201-5223页

作者： chen Zhang Liming Liu yufei Yang yu Sun Jiaxu ning yu Zhang Changsheng Zhang Ying Guo Software College Northeastern UniversityShenyang110169China School of Information science and Engineering Shenyang Ligong UniversityShenyang110159China china Telecom Digital Intelligence technology Co. Ltd.Beijing100035China College of Computer science and Engineering Ningxia Institute of Science and TechnologyShizuishan753000China

The flying foxes optimization(FFO)algorithm,as a newly introduced metaheuristic algorithm,is inspired by the survival tactics of flying foxes in heat wave *** preferentially selects the best-performing *** tendency will cause the newly generated solution to remain closely tied to the candidate optimal in the search *** address this issue,the paper introduces an opposition-based learning-based search mechanism for FFO algorithm(IFFO).Firstly,this paper introduces niching techniques to improve the survival list method,which not only focuses on the adaptability of individuals but also considers the population’s crowding degree to enhance the global search ***,an initialization strategy of opposition-based learning is used to perturb the initial population and elevate its ***,to verify the superiority of the improved search mechanism,IFFO,FFO and the cutting-edge metaheuristic algorithms are compared and analyzed using a set of test *** results prove that compared with other algorithms,IFFO is characterized by its rapid convergence,precise results and robust stability.

关键词： Flying foxes optimization(FFO)algorithm opposition-based learning niching techniques swarm intelligence metaheuristics evolutionary algorithms

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

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World Journal of Stem Cells 2024年第6期16卷 708-727页

作者： Lei-Mei Xu Xin-Xin yu ning Zhang Yi-Song chen Department of Gynecology Obstetrics and Gynecology Hospital of Fudan UniversityShanghai 200011China Department of Gynecology Shanghai Key Laboratory of Female Reproductive Endocrine-related DiseasesShanghai 200011China

BACKGROUND Pelvic organ prolapse(POP)involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity,and vaginal structure is an essential *** POP,the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and *** intricate etiology of POP and the prohibition of trans-vaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy *** umbilical cord mesenchymal stromal cells(hucMSCs)present limitations,but their exosomes(hucMSC-Exo)are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix *** inflammation in POP group fibroblasts,stimulated primary fibroblast growth,and elevated collagen I(Col1)production in ***-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11(MMP11)*** HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in *** miRNAs in hucMSC-Exo targeted and downregulated MMP11 ***-Exo-based therapy may be ideal for safely and effectively treating POP.

关键词： Pelvic organ prolapse Exosomes Fibroblasts Human umbilical cord mesenchymal stromal cells Extracellular matrix Collagen I

Aboveground carbon sequestration of Cunninghamia lanceolata forests:Magnitude and drivers

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Forest Ecosystems 2024年第1期11卷 32-41页

作者： chen Wang Shuguang Liu yu Zhu Andrew R.Smith Ying ning Deming Deng National Engineering Laboratory for Applied technology of Forestry&Ecology in South china Central South University of Forestry and TechnologyChangsha 410004China technology Innovation Center for Ecological Conservation and Restoration in Dongting Lake Basin Ministry of Natural ResourcesChangsha 410007China College of Life science and technology Central South University of Forestry and TechnologyChangsha 410004China School of Ecology and Environment Hainan UniversityHaikou 570228China School of Natural sciences Bangor UniversityGwyneddLL572UWUK College of Forestry Central South University of Forestry and TechnologyChangsha 410004China Hunan Prospecting Designing&Research General Institute for Agriculture Forestry&IndustryChangsha 410007China

Understanding the spatial variation,temporal changes,and their underlying driving forces of carbon sequestration in various forests is of great importance for understanding the carbon cycle and carbon management *** carbon density and sequestration in various Cunninghamia lanceolata forests,extensively cultivated for timber production in subtropical china,vary with biodiversity,forest structure,environment,and cultural factors remain poorly explored,presenting a critical knowledge gap for realizing carbon sequestration supply potential through *** on a large-scale database of 449 permanent forest inventory plots,we quantified the spatial-temporal heterogeneity of aboveground carbon densities and carbon accumulation rates in Cunninghamia lanceolate forests in Hunan Province,china,and attributed the contributions of stand structure,environmental,and management factors to the heterogeneity using quantile age-sequence analysis,partial least squares path modeling(PLS-PM),and hot-spot *** results showed lower values of carbon density and sequestration on average,in comparison with other forests in the same climate zone(i.e.,subtropics),with pronounced spatial and temporal ***,quantile regression analysis using carbon accumulation rates along an age sequence showed large differences in carbon sequestration rates among underperformed and outperformed forests(0.50 and 1.80 Mg·ha^(-1)·yr^(-1)).PLS-PM demonstrated that maximum DBH and stand density were the main crucial drivers of aboveground carbon density from young to mature ***,species diversity and geotopographic factors were the significant factors causing the large discrepancy in aboveground carbon density change between low-and high-carbon-bearing *** analysis revealed the importance of culture attributes in shaping the geospatial patterns of carbon *** work highlighted that retaining largesized DBH trees and increasing shade-t

关键词： Carbon density Carbon accumulation rate Forest age Spatial variation Cultural influence