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Science China Chemistry 1992年第3期35卷 329-339页

作者：沈承德易惟熙周正刘东生 j. beer H. OESCHGER G. BONANI M. SUTER W. WOLFLI Concurrent Post at Laboratory of Loess and Quaternary Geology Academia SinicaXi'an 710061PRC. Institute of Geochemistry Academia Sinica Guiyang 550002 PRC Guiyan Institute of Geology Academia Sinica Beijing 100011 PRC Laboratory of Loess and Quaternary Geology Academia Sinica Xi'an 710061 PRC Physics Institute University of Bern Switzerland Institute für Mittelenergiephysik ETH-Zürich Switzerland

In situ cosmogenic ^(10)Be in quartz from loess deposited in the last 2,000,000 a is considered to have been derived mainly from initial ^(10)Be in source regions and it bears abundant information about changes in erosion rates of source regions. As [have been estimated, the concentrations of 'in situ cosmogenic ^(10)Be' in quartz from samples GL47(L1) andGL83 (L2) collected from the Luochuan loess section are 5×10~5 atom/g and 2.2×10~6 atom/g, respectively. As calculated on the basis of the above estimates, the erosion rates of the source regions are: εBeL1=1.5×10^(-3) cm/a for the L1 period (10,000—90,000 a) and εBeL2=3.8×10^(-4) cm/a for the L2 period (130,000—190,000 a). Studies of 'in situ cosmogeuic ^(10)Be' in quartz from loess at deeper levels are expected to be applied to ^(10)Be dating of loess strata.

关键词： in situ cosmogenic ^(10)Be in quartz accelerator mass spectrometer erosion rate.

中国黄土石英中的^(10)Be研究——Ⅰ.“自身成因^(10)Be”与黄土源区侵蚀速率

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中国科学（B辑） 1991年第7期 752-758页

作者：沈承德易惟熙周正刘东生 j. beer H. Oeschger G. Bonani M. Suter W. Wolfli 中国科学院地球化学研究所广州分部中国科学院地质研究所瑞士伯尔尼大学物理研究所瑞士联邦理工大学中能物理研究所

对于0.2Ma以来的黄土堆积物,其石英“自身成因^(10)Be”主要来源于源区初始^(10)Be,载带着源区侵蚀速率变化信息。中国洛川黄土剖面GL 47(L_1),GL83(L_2)两样品石英“自身成因^(10)Be”浓度分别为5×10~5原子/g,2.2×10~6原子/g。据此... 详细信息

对于0.2Ma以来的黄土堆积物,其石英“自身成因^(10)Be”主要来源于源区初始^(10)Be,载带着源区侵蚀速率变化信息。中国洛川黄土剖面GL 47(L_1),GL83(L_2)两样品石英“自身成因^(10)Be”浓度分别为5×10~5原子/g,2.2×10~6原子/g。据此计算的源区侵蚀速率为:L_1期(10—90ka),ε_(BeL_1)=1.5×10^(-3)cm/a;L_2期(130—190k a),ε_(BeL_2)=3.8×10^(-4)cm/a。更深层位黄土石英“自身成因^(10)Be”研究可望用于黄土地层测年。

关键词：石英"自身成因^(10)Be" 加速器质谱侵蚀速率

Deep learning-driven interval uncertainty propagation for aeronautical structures

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Chinese j.urnal of Aeronautics 2024年第12期37卷 71-86页

作者： Yan SHI Michael beer Institute for Risk and Reliability Leibniz Universitat HannoverHannover 30167Germany Department of Civil and Environmental Engineering University of LiverpoolLiverpool L693BXUnited Kingdom International j.int Research Center for Resilient Infrastructure&International j.int Research Center for Engineering Reliability and Stochastic Mechanics Tongji UniversityShanghai 200092China

Interval Uncertainty Propagation(IUP)holds significant importance in quantifying uncertainties in structural outputs when confronted with interval input *** the aviation field,the precise determination of probability models for input parameters of aeronautical structures entails substantial costs in both time and *** an alternative,the use of interval variables to describe input parameter uncertainty becomes a pragmatic *** complex task of solving the IUP for aeronautical structures,particularly in scenarios marked by pronounced nonlinearity and multiple outputs,necessitates innovative *** study introduces an efficient deep learning-driven approach to address the challenges associated with *** proposed approach combines the Deep Neural Network(DNN)with intelligent optimization algorithms for dealing with the IUP in aeronautical *** inventive extremal value-oriented weighting technique is presented,assigning varying weights to different training samples within the loss function,thereby enhancing the computational accuracy of the DNN in predicting extremal values of structural ***,an adaptive framework is established to strategically balance the global exploration and local exploitation capabilities of the DNN,resulting in a predictive model that is both robust and *** illustrate the effectiveness of the developed approach,various applications are explored,including a high-dimensional numerical example and two aeronautical *** obtained results highlight the high computational accuracy and efficiency achieved by the proposed approach,showcasing its potential for addressing complex IUP challenges in aeronautical engineering.

关键词： Uncertainty propagation Interval variable Deep learning Optimization algorithm Aeronautical structure

Performance assessment of borehole arrangements for the design of rectangular shallow foundation systems

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j.urnal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3291-3304页

作者： Marcin Chwała Danko j.j.rez Hector A.j.nsen Michael beer Wrocław University of Science and Technology Poland Institute for Risk and Reliability Leibniz University HannoverGermany Departamento de Obras Civiles Universidad Técnica Federico Santa MaríaChile International j.int Research Center for Resilient Infrastructure&International j.int Research Center for Engineering Reliability and Stochastic Mechanics Tongji UniversityShanghai200092China Institute for Risk and Uncertainty and School of Engineering University of LiverpoolUnited Kingdom

This study proposes a framework to evaluate the performance of borehole arrangements for the design of rectangular shallow foundation systems under spatially variable soil conditions. Performance measures are introduced to quantify, for a fixed foundation layout and given soil sounding locations, the variability level of the foundation system bearing capacities in terms of their mean values and standard deviations. To estimate these measures, the recently proposed random failure mechanism method (RFMM) has been adopted and extended to consider any arrangement of rectangular foundations and boreholes. Hence, three-dimensional bearing capacity estimation under spatially variable soil can be efficiently performed. Several numerical examples are presented to illustrate the applicability of the proposed framework, including diverse foundation arrangements and different soil correlation structures. Overall, the proposed framework represents a potentially useful tool to support the design of geotechnical site investigation programs, especially in situations where very limited prior knowledge about the soil properties is available.

关键词： Foundations Geotechnical engineering Bearing capacity Optimal borehole placement Soil spatial variability

SARS-CoV-2 infection and the brain:direct evidence for brain changes in milder cases

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Signal Transduction and Targeted Therapy 2022年第8期7卷 2641-2643页

作者： Nico Sollmann Ambros j.beer Frank Kirchhoff Department of Diagnostic and Interventional Radiology Ulm University Medical CenterUlmGermany Department of Nuclear Medicine Ulm University Medical CenterUlmGermany Institute of Molecular Virology Ulm University Medical CenterUlmGermany

Dear Editor,A recent study published in Nature by Douaud and colleagues1 shows that SARS-CoV-2 infection is associated with longitudinal effects,particularly on brain structures linked to the olfactory cortex,modestly accelerated reduction in global brain volume,and enhanced cognitive ***,even mild COVID-19 can be associated with long-lasting deleterious effects on brain structure and function.

关键词： infection cortex cases

Analysis of Solidification in Spray Atomized and Codeposited Metal-matrix Composites Part Ⅰ: Atomization

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j.urnal of Materials Science & Technology 1995年第3期11卷 79-90页

作者： V.Erukhimovitch and j.Baram(Materials Engineering Department, Ben-Gurion University of Negev, beer-Sheva, Israel) Ben-Gurion Univ of Negev Beersheva Israel

Fluid mechanics, heat transfer and liquid-to-solid phase transformation are assessed in optimizing the spray atomization and codeposition process parameters for size refinement and microstructural uniformity of the deposited material. Atomization gas velocities, atomized droplets velocities, convective heat transfer coefficients, thermal histories of the solidifying droplets, freezing rates, fraction solid evolution and solid-liquid interface propagation velocity are calculated. The influence, on the deposit microstructural features, of process parameters like the atomization gas pressure, the pouring tube orifice diameter, the geometrical features of the atomization device,the potency of , pre-existing or inj.cted as reinforcement, nucleation sites, the wetting angle between the liquid melt bnd impurity particles acting as preferred nucleation sites, the in-flight distance of the solidifying droplets in the atomization chamber, i5 evaluated. As a result of the evaluation, appropriate choice of the adj.stable process parameters for the production of powders and/or deposits with desired grain size and microstructure, can be made.

关键词： Co Figure Atomization Analysis of Solidification in Spray Atomized and Codeposited Metal-matrix Composites Part

Estimation of failure probability in braced excavation using Bayesian networks with integrated model updating

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Underground Space 2020年第4期5卷 315-323页

作者： Longxue He Yong Liu Sifeng Bi Li Wang Matteo Broggi Michael beer Institute for Risk and Reliability Leibniz Universitat HannoverGermany State Key Laboratory of Water Resources and Hydropower Engineering Science Institute of Engineering Risk and Disaster PreventionWuhan UniversityChina School of Civil and Safety Engineering Dalian Jiaotong UniversityChina Institute for Risk and Uncertainty University of LiverpoolUK International j.int Research Center for Engineering Reliability and Stochastic Mechanics Tongji UniversityChina

A probabilistic model is proposed that uses observation data to estimate failure probabilities during *** model integrates a Bayesian network and distanced-based Bayesian model *** the network,the movement of a retaining wall is selected as the indicator of failure,and the observed ground surface settlement is used to update the soil *** responses of wall deflection and ground surface settlement are accurately predicted using finite element *** artificial neural network is employed to construct the response surface relationship using the aforementioned input *** proposed model effectively estimates the uncertainty of influential factors.A case study of a braced excavation is presented to demonstrate the feasibility of the proposed *** update results facilitate accurate estimates according to the target value,from which the corresponding probabilities of failure are *** proposed model enables failure probabilities to be determined with real-time result updating.

关键词： Failure probability Braced excavation Bayesian networks Stochastic model updating Sensitivity analysis

Multidimensional resilience decision-making for complex and substructured systems

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Resilient Cities and Structures 2022年第3期1卷 61-78页

作者： j.lian Salomon j.sper Behrensdorf Niklas Winnewisser Matteo Broggi Michael beer Institute for Risk and Reliability Leibniz University HannoverHanoverGermany Institute for Risk and Uncertainty University of LiverpoolLiverpoolUnited Kingdom International j.int Research Center for Resilient Infrastructure&International j.int Research Center for Engineering Reliability and Stochastic Mechanics Tongji UniversityShanghaiChina

Complex systems,such as infrastructure networks,industrial plants and j.t engines,are of paramount importance to modern ***,these systems are subj.ct to a variety of different *** research focuses not only on monitoring and improving the robustness and reliability of systems,but also on their recoverability from adverse *** concept of resilience encompasses precisely these ***,efficient resilience analysis for the modern systems of our societies is becoming more and more *** to their increasing complexity,system components frequently exhibit significant complexity of their own,requiring them to be modeled as systems,i.e.,***,efficient resilience analysis approaches are needed to address this emerging *** work presents an efficient resilience decision-making procedure for complex and substructured systems.A novel methodology is derived by bringing together two methods from the fields of reliability analysis and modern resilience assessment.A resilience decision-making framework and the concept of survival signature are extended and merged,providing an efficient approach for quantifying the resilience of complex,large and substructured systems subj.ct to monetary *** new approach combines both of the advantageous characteristics of its two original components:A direct comparison between various resilience-enhancing options from a multidimensional search space,leading to an optimal trade-off with respect to the system resilience and a significant reduction of the computational effort due to the separation property of the survival signature,once a subsystem structure has been computed,any possible characterization of the probabilistic part can be validated with no need to recompute the *** developed methods are applied to the functional model of a multistage high-speed axial compressor and two substructured systems of increasing complexity,providing accurate results

关键词： Resilience Decision-making Survival signature Reliability Complex systems Substructured systems

Efficient slope reliability analysis under soil spatial variability using maximum entropy distribution with fractional moments

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j.urnal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1140-1152页

作者： Chengxin Feng Marcos A.Valdebenito Marcin Chwała Kang Liao Matteo Broggi Michael beer Institute for Risk and Reliability Leibniz University HannoverCallinstr.34Hannover30167Germany Chair for Reliability Engineering TU Dortmund UniversityLeonhard-Euler-Str.5Dortmund44227Germany Faculty of Civil Engineering Wrocƚaw University of Science and TechnologyWrocƚawPoland Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu610031China University of Liverpool Institute for Risk and UncertaintyPeach StreetLiverpoolL69 7ZFUnited Kingdom International j.int Research Center for Resilient Infrastructure & International j.int Research Center for Engineering Reliability and Stochastic Mechanics Tongji UniversityShanghaiChina

Spatial variability of soil properties imposes a challenge for practical analysis and design in geotechnical *** latter is particularly true for slope stability assessment,where the effects of uncertainty are synthesized in the so-called probability of *** probability quantifies the reliability of a slope and its numerical calculation is usually quite involved from a numerical *** view of this issue,this paper proposes an approach for failure probability assessment based on Latinized partially stratified sampling and maximum entropy distribution with fractional *** spatial variability of geotechnical properties is represented by means of random fields and the Karhunen-Loève ***,failure probabilities are estimated employing maximum entropy distribution with fractional *** application of the proposed approach is examined with two examples:a case study of an undrained slope and a case study of a slope with cross-correlated random fields of strength parameters under a drained *** results show that the proposed approach has excellent accuracy and high efficiency,and it can be applied straightforwardly to similar geotechnical engineering problems.

关键词： Slope Random field Reliability analysis Maximum entropy distribution Latinized partial stratified sampling

On the friction and adhesion hysteresis between polymer brushes attached to curved surfaces: Rate and solvation effects

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Friction 2015年第2期3卷 148-160页

作者： Sissi de beer G.Dj.idj.KENMOÉ Martin H.MÜSER Materials Science and Technology of Polymers MESA+Institute for NanotechnologyUniversity of TwenteP.O.Box 2177500 AE Enschedethe Netherlands j.lich Supercomputing Centre Institute for Advanced Simulation FZ j.lich 52425 JülichGermany Department of Physics Laboratory of Mechanics Faculty of ScienceUniversity of YaoundéP.O.Box 812YaoundéCameroon

Computer simulations of friction between polymer brushes are usually simplified compared to real systems in terms of solvents and *** most simulations,the solvent is only implicit with infinite compressibility and zero *** addition,the model geometries are parallel walls rather than curved or rough as in *** this work,we study the effects of these approximations and more generally the relevance of solvation on dissipation in polymer-brush systems by comparing simulations based on different solvation *** find that the rate dependence of the energy loss during the collision of brush-bearing asperities can be different for explicit and implicit ***,the non-Newtonian rate dependences differ noticeably between normal and transverse motion,i.e.,between head-on and off-center asperity ***,when the two opposing brushes are made immiscible,the friction is dramatically reduced compared to an undersaturated miscible polymer-brush system,irrespective of the sliding direction.

关键词： polymer brushes biomimetic materials molecular dynamics simulation