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Special Column on Multiscale Stochastic Finite Element Method

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Frontiers of Structural and Civil Engineering 2015年第2期9卷 105-106页

作者： Xu, Xi F. Stefanou, George Proppe, Carsten Wu, Yu Ching Beijing Jiaotong university Beijing China Aristotle university of Thessaloniki Thessaloniki Greece karlsruhe Institute of Technology Karlsruhe Germany Tongji university Shanghai China

In the past decade, multi-scale modelling in mathematical physics and engineering has been growing with vast advancement based on deterministic assumption. Because all information across scales contains a certain level of uncertainty due to incomplete knowledge and inherent chaos with respect to physical laws and parameters, a combination of multi-scale and stochastic techniques becomes a new approach. Incorporation of stochastic process into multi-scale modelling with accurate assessment of uncertainty propagation across scales is highly challenging but essential for a rising number of applications, and in certain areas such models can provide critical insights that deterministic approaches could never predict. In computational mechanics, research topics on discrete-to-continuum, stochastic-to-deterministic, and scale coupling are prioritized as the most significant directions. In the past half century, the finite element method has been a mature and widely-used numerical technique. When both multi-scale and stochastic phenomena are considered, cross-cutting multi-scale stochastic finite element modelling forms a novel research frontier. In this special issue,there are five original research papers relevant to multi-scale stochastic finite element methods or their applications.

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Unveiling the correlation between structural alterations and enhanced high-voltage cyclability in Na-deficient P3-type layered cathode materials via Li incorporation

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Electron 2024年第1期2卷 164-176页

作者： Xiaoxia Yang Suning Wang Hang Li Jochi Tseng Zhonghua Wu Sylvio Indris Helmut Ehrenberg Xiaodong Guo Weibo Hua School of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'anChina School of Chemical Engineering Sichuan UniversityChengduChina Institute for Applied Materials(IAM) Karlsruhe Institute of Technology(KIT)Eggenstein‐LeopoldshafenGermany Diffraction and Scattering Division Japan Synchrotron Radiation Research Institute(JASRI)KoutoSayo‐choSayo‐gunHyogoJapan Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of SciencesBeijingChina

With exceptional capacity during high-voltage cycling,P3-type Nadeficient layered oxide cathodes have captured substantial ***,they are plagued by severe capacity degradation over *** this study,tuning and optimizing the phase composition in layered oxides through Li incorporation are proposed to enhance the high-voltage *** structural dependence of layered Na_(2/3)LixNi_(0.25)Mn_(0.75)O_(2)þδoxides on the lithium content(0.0≤x≤1.0)offered during synthesis is investigated systematically on an atomic ***,increasing the Li content triggers the formation of mixed P2/O3-type or P3/P2/O3-type layered *** the voltage window is 1.5-4.5 V,P3-type Na2/3Ni_(0.25)Mn_(0.75)O_(2)(NL0.0NMO,R3m)material exhibits a sequence of phase transformations throughout the process of(de)sodiation,that is,O3⇌P3⇌O30⇌O3″.Such complicated phase transitions can be effectively suppressed in the Na2/3Li_(0.7)Ni_(0.25)Mn_(0.75)O_(2.4)(NL_(0.7)NMO)oxide with P2/P3/O3-type mixed ***,cathodes made of NL0.7NMO exhibit a substantially enhanced cyclic performance at high voltages compared to that of the P3-type layered NL0.0NMO ***,NL0.7NMO demonstrates an outstanding capacity retention of 98%after 10 cycles at 1 C within 1.5-4.5 V,much higher than that of NL0.0NMO(83%).This work delves into the intricate realm of bolstering the high-voltage durability of layered oxide cathodes,paving the way for advanced sodium-ion battery technologies.

关键词： high-voltage cycling Li incorporation phase transition sodium ion batteries triphasic composites

Morphological stability of three-dimensional cementite rods in polycrystalline system:A phase-field analysis

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Journal of Materials Science & Technology 2021年第18期77卷 252-268页

作者： Tobias Mittnacht P.G.Kubendran Amos Daniel Schneider Britta Nestler Institute of Applied Materials(IAM-CMS) Karlsruhe Institute of Technology(KIT)Strasse am Forum 776131 KarlsruheGermany Institute of Digital Materials Science(IDM) Karlsruhe University of Applied SciencesMoltkestr.3076133 KarlsruheGermany Department of Metallurgical and Materials Engineering National Institute of TechnologyTiruchirappalli-620015Tamil NaduIndia

Transformations accompanying shape-instability govern the morphological configuration and distribution of the phases in a *** to the influence of the microstructure on the properties of a material,in the present work,the stability of three-dimensional rods in a‘representative'polycrystalline system is extensively analysed.A multiphase-field model,which recovers the physical laws and sharpinterface relations,and includes grain boundary diffusion,is adopted to investigate the morphological evolution of the ***,the efficiency of the numerical approach is ensured by establishing the volume-preserving chemical equilibrium through the incorporation TCFe8(CALPHAD)data and solving phase-field evolution in the Allen-Cahn *** morphological evolution of the rod in the representative multiphase system exhibits a unique transformation mechanism which is significantly different from the evolution of an isolated *** is realised that,in a polycrystalline arrangement,irrespective of the initial size of the rod,the shape-change begins with the energy-minimising events at the triple *** early transformation renders a characteristic morphology at the longitudinal ends of the structure,which introduces sufficient driving-force through the curvature-difference for the subsequent morphological *** continued mass transfer to the terminations,ultimately,breaks-off the rod into separate entities that are entangled in the grain *** increase in the aspect ratio of the rod,it is identified that the source of mass transfer,which turns into the ovulation site,shifts from the *** increases the number of fragmentation events and introduces satellite *** size of the satellite particle is dictated by a definite ovulation criterion,which is ascertained by examining the transformation of different-sized rods.A comprehensive understanding of the transformation kinetics and mechanism governing the mo

关键词： Shape instability Pearlite spheroidization Sub-critical annealing Phase-field simulations

O-phosphorylation of Oligopeptides with Phosphoramidite

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Chinese Chemical Letters 1998年第12期9卷 0-0+0-0页

作者： Yan Met LI Yu Fen ZHAO (Bio-organic Phosphorus Chemistry Laboratory, Department of Chemistry,Tsinghua university, Beijing 100084)Herbert WALDMANN (Institute of Organic Chemistry, university of karlsruhe, 76128 Karlsfuhe, Germany) Bio-Organ. Phosphorus Chem. Lab. Department of Chemistry Tsinghua University Beijing 100084 China Institute of Organic Chemistry University of Karlsruhe 76128 Karlsruhe Germany

Phosphopeptides were synthesized with bis-alkyloxy-N,N-dialkylphosphorfollowed by oxidation. Many hydroxyl groups in oligopeptides can be O-phosphorylated in onestep.

关键词： Phosphopeptide phosphoramidite

Nanocrystalline CoCrFeNiMn high-entropy alloy with tunable ferromagnetic properties

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Journal of Materials Science & Technology 2021年第18期77卷 126-130页

作者： Junjie Wang Shangshu Wu Shu Fu Sinan Liu Zhiqiang Ren Mengyang Yan Shuangqin Chen Si Lan Horst Hahn Tao Feng Herbert Gleiter Institute of Nanoscience School of Material Science and EngineeringNanjing University of Science and TechnologyNanjing210094China Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe76021Germany

A nanocrystalline CoCrFeNiMn high-entropy alloy(nc-HEA)with nano-multiphase structure was prepared by inert gas condensation(IGC)using a laser evaporation ***,the laser-IGC nc-HEA exhibits unexpected ferromagnetic behavior and the Curie temperature(T_(c))increased nearly 10 times compared to any CoCrFeNiMn HEAs prepared by various other *** addition,the saturation magnetization(M_s)and T_(c)of the laser-IGC nc-HEA can be controlled via heat treatment,which is resulting from the formation and structural evolution of magnetic nanophases during *** work widens the design toolbox for high-performance nc-HEAs based upon laser-IGC technique.

关键词： Magnetic Nanocrystalline high-entropy alloy Laser-Inert gas condensation Microstructure

Hierarchical delineation and multivariate statistical discrimination of chemozones of the Cauvery Basin,south India:Implications on spatio-temporal scales of stratigraphic correlation

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Petroleum Science 2010年第4期7卷 435-447页

作者： RAMKUMAR Mu. BERNER Z. STBEN D. Department of Geology Periyar University Institute of Palaeoenvironment University of Erlangen-Nuernberg Institute of Mineralogy and Geochemistry University of Karlsruhe

Success in locating oil pools in the Cauvery Basin,south India had been found to be based on the ability to delineate precisely the stratigraphic traps resulting from frequent sea level ***,recognition and delineation of them in terms of depositional units through conventional stratigraphic methods have been elusive owing to the limitations of such methods and lack of unified stratigraphic markers that could be traced at regional and basinal *** paper attempts to recognize depositional units in terms of chemozones,chronologic and lithostratigraphic units by assigning distinct geochemical *** signatures were assigned through hierarchical delineation and discriminant function *** is observed that individual depositional units could be recognized statistically with whole-rock geochemical *** strata under study show two second order chemozones comprising six major chemozones that in turn correspond to third order sea level cycles and minor chemozones at the scale of fourth order and/or further shorter sea level *** geochemical signatures showed 100% distinctness between sample populations categorized according to chronostratigraphy and *** durations of these stratigraphic units range from 18 million years to less than a million years and indicate distinct geochemical compositional change at different time *** implication and also due to the close correspondence between sea level variations reported from this basin and global sea level cycles,it is suggested that recognition and correlation of individual depositional units with distal counterparts could be made *** of these results is that stratigraphic units,at varying scales either temporally or spatially,could be assigned with unique geochemical signature,with which accurate prediction and correlation of similar units elsewhere is possible with measurable accuracy.

关键词： Chemostratigraphy statistical discrimination petroleum exploration stratigraphic correlation

Novel Micromixer with Complex 3D-Shape Inner Units: Design, Simulation and Additive Manufacturing

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Computer Modeling in Engineering & Sciences 2020年第6期123卷 1061-1077页

作者： Di Wang Guangzhao Ye Jingming Mai Xiaomin Chen Yongqiang Yang Yang Li Xiaojun Chen Jie Chen School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou510640China Department of Electrical Engineering and Information Technology Karlsruhe Institute of TechnologyKarlsruhe76131Germany

In this paper,a novel micromixer with complex 3D-shape inner units was put forward and fabricated by metal Additive Manufacturing(AM).The design of the micromixer combined the constraints of selective laser melting technology and the factors to improve mixing ***-Dushman reaction system and Compute Fluid Design(CFD)simulation were conducted to investigate the performance and the mechanism of this novel micromixer to improve mixing *** research found that the best mixing efficiency of this novel micromixer could be gained when the inner units divided fluid into five pieces with a uniform *** with a conventional micromixer without obstacle in the channel,the micromixer designed in this research achieved higher mixing efficiency and reduce the pressure drop by 10.34%.The mixing behaviour in this novel micromixer was discussed,which mainly contains two types:collisions and *** collisions,the fluid micro masses would hit each other directly,which broke the boundaries of micro masses and promoted the interchange of species in the whole flow *** swirls,the fluid micro masses were drawn into thin and long slices,which increased the size of the contact area and enhanced molecule ***,the application scheme of this novel micromixer was briefly discussed.

关键词： Additive manufacturing(AM) micromixer computational fluid dynamics(CFD) selective laser melting(SLM)

Group planting of cherry (Prunus avium L.) fosters growth and tree quality is superior to conventional row planting in Germany

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Journal of Forestry Research 2018年第4期29卷 1088-1099页

作者： Somidh Saha Institute for Technology Assessment and Systems Analysis (ITAS) Karlsruhe Institute of Technology (KIT) Karlstr. 11 76133 Karlsruhe Germany Institute of Forest Sciences University of Freiburg Freiburg Germany

Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an import

关键词： Group planting Tree growth Tree quality Interspecific competition Intraspecific competition Photosynthetically active photon flux density Total sitefactor

TiNiHf/SiO_(2)/Si shape memory film composites for bidirectional micro actuation

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International Journal of Smart and Nano Materials 2022年第2期13卷 293-314页

作者： Sabrina M.Curtis Marian Sielenkamper Gowtham Arivanandhan Duygu Dengiz Zixiong Li Justin Jetter Lisa Hanke Lars Bumke Eckhard Quandt Stephan Wulfinghoff Manfred Kohl Institute for Materials Science Kiel University(CAU)KielGermany Materials Science and Engineering University of MarylandCollege ParkMDUnited States Institute of Microstructure Technology Karlsruhe Institute of Technology(KIT)KarlsruheGermany

The martensitic phase transformation in Ti_(40.4)Ni_(48)Hf_(11.6) shape memory alloys is leveraged for bi-directional actuation with TiNiHf/SiO_(2)/Si *** shape memory properties of magnetron sputtered Ti_(40.4)Ni_(48)Hf_(11.6) films annealed at 635℃-5 min are influenced by film thickness and the underlying *** TiNiHf film thick-ness from 21μm to 110 nm results in the reduction of all characteristic transformation temperatures until a critical thickness is ***,Ti_(40.4)Ni_(48)Hf_(11.6) thin films as low as 220 nm show transfor-mations above room temperature when deposited on SiO_(2) buffer layer,which is of great interest in *** comparison,220 nm films on Si substrates are austenitic at room temperature,and thus not suitable for *** fatigue tests on TiNiHf/SiO_(2)/Si bimorphs demonstrate better functional fatigue characteristics than freestanding films,with an average reduction of 15℃ after 125 cycles,with tempera-ture stabilization *** bi-directional actuation results are promising in the development of bistable actuators within a PMMA/TiNiHf/Si trimorph composite,whereby the additional PMMA layer undergoes a glass transition at 105℃.With the aid of constitutive modeling,a route is elaborated on how bistable actuation can be achieved at micro-to nanoscales by showing favorable thickness combinations of PMMA/TiNiHf/Si composite.

关键词： Bimorph microactuator NiTiHf bistable actuator shape memory alloy thin films