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Data-driven Bayesian inference of turbulence model closure coefficients incorporating epistemic uncertainty

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Acta Mechanica sinica 2021年第12期37卷 1812-1838页

作者： Daigo Maruyama Philipp Bekemeyer stefan Gortz simon Coggon sanjiv sharma German Aerospace Center(DLR) Institute of Aerodynamics and Flow Technology Lilienthalplatz 738108 BraunschweigGermany Airbus Operations Limited Pegasus House Aerospace AveFiltonBristol BS347PA

We introduce a framework for statistical inference of the closure coefficients using machine learning *** objective of this framework is to quantify the epistemic uncertainty associated with the closure model by using experimental data via Bayesian *** framework is tailored towards cases for which a limited amount of experimental data is *** consists of two ***,by treating all latent variables(non-observed variables)in the model as stochastic variables,all sources of uncertainty of the probabilistic closure model are quantified by a fully Bayesian *** probabilistic model is defined to consist of the closure coefficients as parameters and other parameters incorporating ***,the uncertainty associated with the closure coefficients is extracted from the overall uncertainty by considering the noise being *** overall uncertainty is rigorously evaluated by using Markov-Chain Monte Carlo sampling assisted by surrogate *** apply the framework to the spalart-Allmars one-equation turbulence *** test cases are considered,including an industrially relevant full aircraft model at transonic flow conditions,the Airbus ***,we demonstrate that epistemic uncertainties in the closure coefficients result into uncertainties in flow quantities of interest which are prominent around,and downstream,of the shock occurring over the XRF1 *** data-driven approach could help to enhance the predictive capabilities of CFD in terms of reliable turbulence modeling at extremes of the flight envelope if measured data is available,which is important in the context of robust design and towards virtual aircraft *** plentiful amount of information about the uncertainties could also assist when it comes to estimating the influence of the measured data on the inferred model ***,the developed framework is flexible and can be applied to different test cases and to various turbulence model

关键词： Turbulence modeling Uncertainty quantification Parameter calibration Bayesian statistics surrogate-assisted methods spalart-Allmaras one-equation turbulence model Large-scale industrial aircraft use-case

A Bibliometric Framework for Identifying"Princes"Who Wake up the"sleeping Beauty"in Challenge-type scientific Discoveries

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Journal of Data and Information science 2016年第1期1卷 50-68页

作者： Jian du YishanWu school of Information Management Nanjing UniversityNanjing 210032China Institute of Medical Information&Library Chinese Academy of Medical SciencesBeijing 100005China Chinese Academy of science and Technology for Development Beijing 100038China

Purpose： This paper develops and validates a bibliometric framework for identifying the ＂princes＂（PR） who wake up the ＂sleeping beauty＂（sB） in challenge-type scientific discoveries, so as to figure out the awakening mechanisms, and promote potentially valuable but not readily accepted innovative research. （A PR is a research study.） Design/methodology/approach： We propose that PR candidates must meet the following four criteria：（1） be published near the time when the sB began to attract a lot of citations; （2） be highly cited papers themselves; （3） receive a substantial number of co-citations with the sB; and （4） within the challenge-type discoveries which contradict established theories, the ＂pulling effect＂ of the PR on the sB must be strong. We test the usefulness of the bibliometric framework through a case study of a key publication by the 2014 chemistry Nobel laureate stefan W. Hell, who negated Ernst Abbe＇s diffraction limit theory, one of the most prominent paradigms in the natural sciences. Findings： The first-ranked candidate PR article identified by the bibliometric framework is in line with historical facts. An sB may need one or more PRs and even ＂retinues＂ to be ＂awakened.＂ Documents with potential awakening functionality tend to be published in prestigious multidisciplinary journals with higher impact and wider scope than the journals publishing sBs. Research limitations： The above framework is only applicable to transformative innovations, and the conclusions are drawn from the analysis of one typical sB and her awakening process. Therefore the generality of our work might be limited. Practical implications： Publications belonging to so-called transformative research, even when less frequently cited, should be given special attention as early as possible, because they may suddenly attract many citations after a period of sleep, as reflected in our case ***/value： The definition of PR（s） as the first paper（s） that cited the sB article

关键词： Citation history Delayed recognition Awakening mechanisms Transformativeinnovation Nobel Prize

Three-dimensional structured on-chip stacked zone plates for nanoscale X-ray imaging with high efficiency

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Nano Research 2014年第4期7卷 528-535页

作者： stephan Werner stefan Rehbein Peter Guttmann Gerd schneider Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH Institute for Soft Matter and Functional Materials Albert-Einstein-Straβe15 12489 Berlin Germany

Fresnel zone plates are the key optical elements for nanoscale focusing of X-ray beams with high spatial resolution. Conventional zone plates manufactured by planar nanotechnology processes are limited by the achievable aspect ratios of their zone structures. Additionally, ultra-high resolution X-ray optics with high efficiency requires three-dimensional （3-D） shaped tilted zones. The combination of high spatial resolution and high diffraction efficiency is a fundamental problem in X-ray optics. Based on electrodynamical simulations, we find that the optimized zone plate profile for volume diffraction is given by zone structures with radially increasing tilt angles and decreasing zone heights. On-chip stacking permits the realization of such advanced 3-D profiles without significant loss of the maximum theoretical efficiency. We developed triple layer on-chip stacked zone plates with an overlay accuracy of sub-2 nm which fulfills the nanofabrication requirements. Efficiency measurements of on-chip stacked zone plates show significantly increased values compared to conventional zone plates.

关键词： X-ray optics Fresnel zone plates X-ray imaging X-ray microscopy volume diffraction

The innate immune response to allotransplants: mechanisms and therapeutic potentials

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Cellular & Molecular Immunology 2019年第4期16卷 350-356页

作者： Jordi Ochando Farideh Ordikhani Peter Boros stefan Jordan Department of Oncological sciences Icahn School of Medicine at Mount SinaiNew YorkNYUSA Immunología de Trasplantes Centro Nacional de MicrobiologíaInstituto de Salud Carlos IIIMadridSpain

surgical trauma and ischemia reperfusion injury(IRI)are unavoidable aspects of any solid organ transplant *** trigger a multifactorial antigen-independent inflammatory process that profoundly affects both the early and long-term outcomes of the transplanted *** injury associated with donor organ procurement,storage,and engraftment triggers innate immune activation that inevitably results in cell death,which may occur in many different *** cells in donor grafts release damage-associated molecular patterns(DAMPs),which alert recipient innate cells,including macrophages and dendritic cells(DCs),through the activation of the complement cascade and toll-like receptors(TLRs).The long-term effect of inflammation on innate immune cells is associated with changes in cellular metabolism that skew the cells towards aerobic glycolysis,resulting in innate immune cell activation and inflammatory cytokine *** different roles of proinflammatory cytokines in innate immune activation have been described,and these cytokines also stimulate optimal T-cell expansion during allograft ***,early innate immune events after organ transplantation determine the fate of the adaptive immune *** this review,we summarize the contributions of innate immunity to allograft rejection and discuss recent studies and emerging concepts in the targeted delivery of therapeutics to modulate the innate immune system to enhance allograft survival.

关键词： metabolism immunity inflammation

Failure analysis of a kind of low power connector

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Journal of Zhejiang University-science A(Applied Physics & Engineering) 2007年第3期8卷 384-392页

作者： ZHOU Yi-lin ZENG Ning XU Liang-jun JORGENs stefan Research Lab of Electric Contacts Beijing University of Posts ＆ Telecommunications Beijing 100876 China Lumberg Connect GmbH ＆ Co. KG Schalksmiihle 58579 Germany

A kind of low power connector used e.g. in household appliances was partly burned in routine experiment. The heat sources were four paralleled contacts constructed by springs (sn/Cusn-alloy) in socket and a plug sheet (Ni/steel) while mating. The contact interfaces were detected by scanning electronic microscope (sEM) and X-ray energy dispersive spectros- copy (XEDs), obvious wear tracks and various contaminants, including element si, Al, Na, K, s, Cl, O, etc., were found. The contamination degrees on the four paralleled contacts were different, so that the ratio of average contact resistance on the four contacts was about 5:8:3:1. The maximum contact resistance on contacts of the plug sheet reached 28 ?. The main failure rea- sons were fretting and contamination between the contact interfaces. Fretting simulation showed that connection resistance of connectors was raised up, even to ohms level. When the current increased to 5 A, the socket housing was heated and decom- posed. By the thermal analysis, it was estimated that the connector would be burned under the lower current if the current was not evenly distributed on the four paralleled contacts caused by uneven contamination. Improvement methods for connector failure are also discussed.

关键词： Connector Thermal failure Fretting Contamination

How do altitude and soil properties influence the taxonomic and phylogenetic structure and diversity of Brazilian páramo vegetation?

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Journal of Mountain science 2020年第5期17卷 1045-1057页

作者： Markus GAsTAUER Jan THIELE stefan POREMBsKI Andreza Viana NERI Instituto Tecnologico Vale R.Boaventura da Silva955CEP 66055-090Bairro NazareBelemPABrazil Universidade Federal do Para Programa de pos-graduacao em EcologiaRuaAugusto Correa01CEP 66075-110GuamaBelemBrazil Thünen Institute Institute of BiodiversityBundesallee 6538116 BraunschweigGermany University of Rostock Institute of BioscienceDepartment of Botany and Botanical GardenWismarsche Str.44/45D-18051 RostockGermany Universidade Federal de Vicosa Department of Plant BiologyLaboratory of Ecology and Evolution of PlantsCampus Universitario s/n36570-900VigosaMinas GeraisBrazil

Altitude and environmental variables such as edaphic properties are considered determinants of species distribution and community composition in mountain ***,we aimed to outline the effects of distinct mountain peaks,altitude and soil properties on community composition,species density,phylogenetic structure and diversity of angiosperm páramo communities from the serra do Brigadeiro state Park,Minas Gerais,southeastern *** that,we identified all angiosperm species found in 300 plots(1 m×1 m)from three mountain peaks,measured soil depth and analyzed soil fertility and texture in each *** reduce the number of soil variables and species composition,we computed principal coordinates based on soil properties and principal coordinates based on species-plot matrix for each ***,we computed the standard effect sizes of the mean phylogenetic pairwise distance and the mean nearest phylogenetic taxon distance for each plot to investigate differences in the degree of relatedness among coexisting *** compared differences in response variables between peaks and modelled them in function of altitude and principle components of soil properties using mixed effect *** density and phylogenetic diversity differed between peaks,but,contrary to the previous findings,no relationships between species richness or phylogenetic diversity and altitude or soil properties were found,indicating that further investigations are necessary to understand the altitude-biodiversity relationship in Brazilian páramo *** composition differed between peaks and depended on altitude,soil properties and interactions between them,indicating that upward shifting of bioclimatic conditions.due to climate changes may alter communities of this *** structure differed between peaks and was influenced by altitude and soil *** phylogenetic clustering increased with altitude,eventual upward movements of species in Brazilian

关键词： Mountainous ecosystems Altitudebiodiversity relationship High altitude grasslands Phylogenetic diversity Community assemblage Conservation

High resolution, binder-free investigation of the intrinsic activity of immobilized NiFe LDH nanoparticles on etched carbon nanoelectrodes

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Nano Research 2018年第11期11卷 6034-6044页

作者： Patrick Wilde stefan Barwe Corina Andronescu Wolfgang schuhmann Edgar Ventosa Analytical Chemistry - Center for Electroche.mical sciences (CEs) Ruhr-Universitat Bochum Universitasstr. 150 D-44780 Bochum Germany IMDEA Energy Avda. Ramo de la Sagra 3 28935 Motoles Spain

The determination of the intrinsic properties of nanomaterials is essential for their optimization as electrocatalysts, however it poses great challenges from the standpoint of analytical tools and methods. Herein, we report a novel methodology that allows for a binder-free investigation of electrocatalyst nanoparticles. The potential-assisted immobilization of a non-noble metal catalyst, i.e., nickel-iron layered double hydroxide (NiFe LDH) nanoparticles, was employed to directly attach small nanoparticle ensembles from a suspension to the surface of etched carbon nanoelectrodes. The dimensions of this type of electrodes allowed for the immobilization of the catalyst material below the picogram scale and resulted in a high resolution towards the faradaic current response. In addition the effect of the electrochemical aging on the intrinsic activity of the catalyst was investigated in alkaline media by means of continuous cyclic voltammetry. A change in the material properties could be observed, which was accompanied by a substantial decrease in its intrinsic activity.

关键词： oxygen evolution reaction nickel-iron layered double hydroxide (NiFe LDH) immobilization nanoelectrocatalysis nanoelectrodes nanoimpacts

Mutation D614G increases sARs-CoV-2 transmission

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signal Transduction and Targeted Therapy 2021年第4期6卷 1075-1076页

作者： Prerna Arora stefan Pohlmann Markus Hoffmann Infection Biology Unit German Primate CenterGottingenGermany Faculty of Biology and Psychology Georg-August-University GottingenGottingenGermany

It has been unclear why sARs-CoV-2 with a D614G mutation in the spike protein became dominant early in the COVID-19 pandemic.A recent study by Hou et *** in science shows that D614G increases sARs-CoV-2 spread in cult... 详细信息

关键词： 4G D61 spread

A method for large-scale implantation of 3D microdevice ensembles into brain and soft tissue

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Microsystems & Nanoengineering 2020年第1期6卷 199-211页

作者： stefan A.sigurdsson Zeyang Yu Joonhee Lee Arto Nurmikko school of Engineering Brown UniversityProvidenceRI 02912USA Department of Neurology Massachusetts General HospitalBostonMA 02114USA Department of Physics and Astronomy West Virginia UniversityMorgantownWV 26506USA Department of Neuroscience West Virginia UniversityMorgantownWV 26506USA

Wireless networks of implantable electronic sensors and actuators at the microscale(sub-mm)level are being explored for monitoring and modulation of physiological activity for medical diagnostics and therapeutic *** the requirement of integrating multiple electronic or chemical functions within small device volumes,a key challenge is the development of high-throughput methods for the implantation of large numbers of microdevices into soft tissues with minimal *** that end,we have developed a method for high-throughput implantation of~100–200µm size devices,which are here simulated by proxy microparticle *** generally applicable to subdermal tissue,our main focus and experimental testbed is the implantation of microparticles into the *** method deploys a scalable delivery tool composed of a 2-dimensional array of polyethylene glycol-tipped microneedles that confine the microparticle *** dissolution of the bioresorbable polyethylene glycol,the supporting array structure is retrieved,and the microparticles remain embedded in the tissue,distributed spatially and geometrically according to the design of the microfabricated delivery *** first evaluated the method in an agarose testbed in terms of spatial precision and throughput for up to 1000 passive spherical and planar microparticles acting as proxy *** then performed the same evaluations by implanting particles into the rat cortex under acute conditions and assessed the tissue injury produced by our method of implantation under chronic conditions.

关键词： implantation method integrating