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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 592-602页

作者： Dianlei Feng Xuerui Wang Udo Nackenhorst Xuming Zhang Pengzhi Pan Department of Hydraulic Engineering Tongji UniversityShanghai200092China Institute of Fluid Mechanics and Environmental Physics in Civil Engineering Leibniz University HannoverHannover30167Germany Institute of Mechanics and Computational Mechanics Leibniz University HannoverHannover30167Germany State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

In this study,we carried out a comparative study of two different numerical strategies for the modeling of the biogeochemical processes in microbially induced calcite precipitation(MICP)process.A simplified MICP model was used,which is based on the mass transport *** numerical strategies,namely the operator splitting(OS)and the global implicit(GI)strategies,were adopted to solve the coupled reactive mass transport *** two strategies were compared in the aspects of numerical accuracy,convergence property and computational efficiency by solving the presented MICP *** look more into the details of the model,sensitivity analysis of some important modeling parameters was also carried out in this paper.

关键词： Microbially induced calcite precipitation(MICP) Advection-diffusion-reaction(ADR)equation Time discontinuous Galerkin(TDG)method Open Geo Sys-PHREEQC

Recent behavior and possible future evolution of the glacieret in the cirque Golemiya Kazan in the Pirin Mountains under conditions of climate warming

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Journal of Mountain Science 2019年第1期16卷 16-29页

作者： Peter NOJAROV Emil GACHEV Karsten GRUNEWALD National Institute of Geophysics Geodesy and Geography Bulgarian Academy of Sciences South-West university "Neofit Rilski" leibniz Institute of Ecological Urban and Regional Development

This research reveals relationships between climate variables and inter-annual dynamics in the area of the glacieret located in the cirque Golemiya Kazan in the Pirin Mountains. The study period is 1993–2017. The correlations are identified using statistical methods. Also, a statistical model is constructed, including some climate variables as predictors. Despite the evident decrease of the glacieret's size in the period from the 1950 s onwards, the long-term trends for the last decades have been insignificant. The main climatic factors influencing the inter-annual dynamics in the area of the glacieret are air temperature, precipitation, zonal and meridional winds and relative humidity. With respect to the dynamics in the area of the glacieret, the important trends in the different climate variables are those of the warm period air temperatures and zonal(u) wind. They also determine to a great extent its future development by acting in two opposite directions – rising temperatures in the warm period will lead to a rapid decrease of its area by the end of the melting season, while the change of wind directionfrom west to east in the warm period will increase its area. The influence of the zonal wind in the warm period is explained mainly by the location of the glacieret in the cirque. Generally, the glacieret is tilted downwards from west to east. Thus, westerly winds facilitate blowing away the snow from the surface of the glacieret, assisting its melting in the warm period. Easterly winds do not have such an effect. The combination of the opposite effects of these two most important climate variables leads to the most likely scenario for the future development of the glacieret, according to which by the middle of this century it is expected to turn into a semi-permanent snow patch, which disappears after some summers, and by the end of the century to completely melt every year before the end of the melting season.

关键词： Climate warming Glacieret Pirin Mountains Statistical modeling Glacieret area Projection

Extracting local nucleation fields in permanent magnets using machine learning

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npj Computational Materials 2020年第1期6卷 924-933页

作者： Markus Gusenbauer Harald Oezelt Johann Fischbacher Alexander Kovacs Panpan Zhao Thomas George Woodcock Thomas Schrefl Department for Integrated Sensor Systems Danube University KremsKrems an der DonauAustria Institute for Metallic Materials Leibniz IFW DresdenDresdenGermany

Microstructural features play an important role in the quality of permanent *** coercivity is greatly influenced by crystallographic defects,like twin boundaries,as is well known for *** would be very useful to be able to predict the macroscopic coercivity from microstructure *** this is not possible now,in the present work we examine a related question,namely the prediction of simulated nucleation fields of a quasi-three-dimensional(rescaled and extruded)system constructed from a two-dimensional image.

关键词： microstructure permanent magnets

Oxygen tolerance capacity of upflow anaerobic solid-state(UASS) with anaerobic filter(AF) system

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Journal of Environmental Sciences 2016年第7期28卷 200-206页

作者： Yao Meng Carsten Jost Jan Mumme Kaijun Wang Bernd Linke State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Department Bioengineering Leibniz Institute for Agricultural Engineering UK Biochar Centre School of Geo Sciences University of Edinburgh

In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state（UASS）with anaerobic filter（AF） system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0–431 m L O2/gvswere conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431 m L O2/gvsincreased the methane yield by 82.2%. Aeration intensities of 0–355 m L O2/gvswere conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen（DO） of UASS and AF reactors kept around 1.39 ±0.27 and 0.99 ± 0.38 mg/L, respectively. p H was relatively stable around 7.11 ± 0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85 ± 7 m L/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity.

关键词： Anaerobic digestion Oxygen tolerance capacity UASS Maize straw Microaeration Solid-state

Reliability and reliability sensitivity analysis of structure by combining adaptive linked importance sampling and Kriging reliability method

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Chinese Journal of Aeronautics 2020年第4期33卷 1218-1227页

作者： Fuchao LIU Pengfei WEI Changcong ZHOU Zhufeng YUE School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710129China Institute for Risk and Reliability Leibniz Universitat HannoverCallinstr.34HannoverGermany

The application of reliability analysis and reliability sensitivity analysis methods to complicated structures faces two main challenges:small failure probability(typical less than 10-5)and time-demanding mechanical *** paper proposes an improved active learning surrogate model method,which combines the advantages of the classical Active Kriging–Monte Carlo Simulation(AK-MCS)procedure and the Adaptive Linked Importance Sampling(ALIS)*** proposed procedure can,on the one hand,adaptively produce a series of intermediate sampling density approaching the quasi-optimal Importance Sampling(IS)density,on the other hand,adaptively generate a set of intermediate surrogate models approaching the true failure surface of the rare failure ***,the small failure probability and the corresponding reliability sensitivity indices are efficiently estimated by their IS estimators based on the quasi-optimal IS density and the surrogate *** with the classical AK-MCS and Active Kriging–Importance Sampling(AK-IS)procedure,the proposed method neither need to build very large sample pool even when the failure probability is extremely small,nor need to estimate the Most Probable Points(MPPs),thus it is computationally more efficient and more applicable especially for problems with multiple *** effectiveness and engineering applicability of the proposed method are demonstrated by one numerical test example and two engineering applications.

关键词： Active learning Kriging model Adaptive linked importance sampling Reliability analysis Sensitivity analysis Small failure probability

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

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Frontiers of Chemical Science and Engineering 2018年第3期12卷 376-382页

作者： Kai Wang Jinbo Pang Liwei Li Shengzhe Zhou Yuhao Li Tiezhu Zhang College of Automation and Electric Engineering Qingdao University Qingdao 266071 China The leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden) Dresden D-01069 Germany

Carbon nanotubes/graphene composites have superior mechanical, electrical and electrochemistry prop- erties with carbon nanotubes as a hydrophobicity boosting agent. Their extraordinary hydrophobic performance is highly suitable for electrode applications in lithium ion batteries and supercapacitors which often employ organic electrolytes. Also the hydrophobic features enable the oil enrichment for the crude oil separation from seawater. The ever reported synthesis routes towards such a composite either involve complicated multi-step reactions, e.g., chemical vapor depositions, or lead to insufficient extru- sion of carbon nanotubes in the chemical reductions of graphene oxide, e.g., fully embedding between the compact graphene oxide sheets. As a consequence, the formation of standalone carbon nanotubes over graphene sheets remains of high interests. Herein we use the facile flash light irradiation method to induce the reduction of graphene oxides in the presence of carbon nanotubes. Photographs, micrographs, X-ray diffraction, infrared spectroscopy and thermogravimetric analysis all indicate that graphene oxides has been reduced. And the contact angle tests confirm the excellent hydrophobic perfor- mances of the synthesized carbon nanotube/reduced graphene oxide composite films. This one-step treatment represents a straightforward and high efficiency way for the reduction of carbon nanotubes/graphene oxides composites.

关键词： carbon nanotubes graphene composite flash irradiation method reduced graphene oxide contact angles

Prediction of the biogas production using GA and ACO input features selection method for ANN model

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Information Processing in Agriculture 2019年第3期6卷 349-356页

作者： Tanja Beltramo Michael Klocke Bernd Hitzmann Institute of Food Science and Biotechnology University of HohenheimStuttgart 70599Germany leibniz Institute for Agricultural Engineering and Bioeconomy Potsdam 14469Germany

This paper presents a fast and reliable approach to analyze the biogas production process with respect to the biogas production *** experimental data used for the developed models included 15 process variables measured at an agricultural biogas plant in *** this context,the concentration of volatile fatty acids,total solids,volatile solids acid detergent fibre,acid detergent lignin,neutral detergent fibre,ammonium nitrogen,hydraulic retention time,and organic loading rate were *** neural networks(ANN)were established to predict the biogas production *** ant colony optimization and genetic algorithms were implemented to perform the variable *** identified the significant process variables,reduced the model dimension and improved the prediction capacity of the ANN *** best prediction of the biogas production rate was obtained with an error of prediction of 6.24%and a coefficient of determination of R2=0.9.

关键词： Ant colony optimization Artificial neural networks Biogas Genetic algorithm

Gottfried Konecny:From draftsman to Professor emeritus-75 years of involvement in photogrammetry and remote sensing

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Geo-Spatial Information Science 2021年第1期24卷 1-4,I0001页

作者： Christian Heipke Deren Li Institute of Photogrammetry and GeoInformation(IPI) Leibniz University HannoverHannoverGermany State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

This special issue is dedicated to *** Konecny(see Figure 1),the former president of the International Society for Photogrammetry and Remote Sensing(ISPRS)on the occasion of his 90th birthday,which he celebrated in good health and spirits in June 2020(see Figure 2).A visionary leader and missionary of global topographic mapping,a world scientist and a world citizen who restlessly built and continues to build sustainable bridges between different generations and different peoples of the globe and a true pioneer of photogrammetry and remote sensing,Konecny has shaped our field of research and development over the last 75 years in ways second to *** also has a very special connection to China,which prompted the Editor-in-Chief of Geo-spatial Information Science to suggest this journal as a very good place to publish this special *** the successor of *** at the Institute of Photogrammetry and GeoInformation of leibniz university Hannover,it is with great honor,joy and thankfulness that Christian Heipke accepted the invitation to be guest editor of this special issue,together with Deren Li.

关键词： gramme Figure involvement

Identification of surface nanobubbles and resolving their size-dependent stiffness

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Science China(Physics,Mechanics & Astronomy) 2020年第9期63卷 66-76页

作者： YouQuan Jia BinYu Zhao Abbasali Abouei Mehrizi Chuan Wang Yi Xu LongQuan Chen School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China School of Physics University of Electronic Science and Technology of ChinaChengdu 610054China leibniz Institute of Polymer Research Dresden Dresden 01069Germany

We report a comparative investigation of the topographic features and nanomechanical responses of surface nanobubbles,polymeric nanodrops,and solid microparticles submerged in water and probed by atomic force microscopy in different operating *** show that these microscopic objects exhibit similar topographies,either hemispherical or hemiellipsoidal,in the standard tapping mode,and thus are difficult to ***,distinct differences,caused not only by their different mechanical properties but also by different cantilever tip-sample mechanical interactions that are affected by tip wettability,were observed in successive topographic imaging with controlled scanning forces and the nanoindentation tests,allowing for the identification of surface *** on the indentation force-distance curves,we further extrapolated the stiffness of surface nanobubbles spanning a wide range of sizes and then developed a simple theoretical model to explain this size *** also demonstrate how size-dependent stiffness can be used to determine the surface tension of nanobubbles,which was found to be much lower than the bulk value of water.

关键词： surface nanobubble size-dependent stiffness nanomechanical measurement atomic force microscopy

Strain tunable quantum dot based non-classical photon sources

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Journal of Semiconductors 2020年第1期41卷 56-71页

作者： Jingzhong Yang Michael Zopf Fei Ding Institute of Solid State Physics Leibniz University of Hannover

Semiconductor quantum dots are leading candidates for the on-demand generation of single photons and entangled photon *** photon quality and indistinguishability of photons from different sources are critical for quantum information *** inability to grow perfectly identical quantum dots with ideal optical properties necessitates the application of post-growth tuning techniques via ***,electric,magnetic or strain *** this review,we summarize the state-of-the-art and highlight the advantages of strain tunable non-classical photon sources based on epitaxial quantum *** piezoelectric crystals like PMN-PT,the wavelength of single photons and entangled photon pairs emitted by InGaAs/GaAs quantum dots can be tuned *** with quantum light-emitting diodes simultaneously allows for electrical triggering and the tuning of wavelength or exciton fine *** from light hole exciton can be tuned,and quantum dot containing nanostructure such as nanowires have been *** ensure the indistinguishability of photons from distant emitters,the wavelength drift caused by piezo creep can be compensated by frequency feedback,which is verified by two-photon interference with photons from two stabilized ***,strain tuning proves to be a flexible and reliable tool for the development of scalable quantum dots-based non-classical photon sources.

关键词： quantum dot entangled photons strain tuning piezoelectric crystal fine structure splitting on-chip