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Friction 2019年第2期7卷 181-191页

作者： Le JIN Herbert SCHEERER Georg ANDERSOHN Matthias OECHSNER dieter HELLMANN Center for Structural Materials Technische Universit?t Darmstadt KSB

Silicon carbide(SiC) can be tribo-chemically smoothened during a self-mated sliding procedure in the aqueous environment. As well reported in the point-contact tests, this smoothening process works well due to the abundant water as oxidant. After this smoothening process, the tribo-surface is well polished, a closely mated tribo-gap naturally forms, and an ultra-low friction state is built. However, water in the tribo-gap could be insufficient in industrial applications, e.g., the seal gap in mechanical seals. In this study, the tribo-chemical smoothening behavior in such environment was researched. A surface-contact reciprocating test was used to simulate the aqueous environment where water was insufficient. After tests, compared to the published results from the point-contact tests, the same ultra-low friction state was achieved. A part of the tribo-surface was tribo-chemically smoothened. The obtained smoothened surface microstructure was consistent with the published information. Meanwhile, severe abrasive wear occurred. A porous oxygen-rich layer was found existing beneath the abrasion-induced grooves, in which numerous smashed wear debris adhered on the worn surfaces. We concluded that the shortage of water initiated the severe abrasion, meanwhile the generated wear debris aggravated the wear condition. This understanding is instructive for developing new methods to avoid the severe abrasion in the same water insufficient environment.

关键词： silicon carbide surface-contact sliding friction tribo-chemical smoothening abrasion ultra-low friction mechanical seal

Vitamin C and Vitamin D—friends or foes in modulating γδ T-cell differentiation?

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Cellular & Molecular Immunology 2022年第10期19卷 1198-1200页

作者： Christian Peters Katharina Klein dieter Kabelitz Institute of Immunology Christian-Albrechts UniversityKielGermany

The differentiation and functional plasticity of T cells are transcriptionally and epigenetically regulated by signals imposed by the local cytokine milieu and a variety of additional factors,including *** C has pleiotropic functions in the immune *** exerts antioxidant activity,can directly kill selected tumor targets,promotes early T-cell differentiation,and enhances Th1 cytokine production in mature T cells[1,2].

关键词： vitamin cytokine Vitamin

A High Order Sharp-Interface Method with Local Time Stepping for Compressible Multiphase Flows

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Communications in Computational Physics 2011年第1期9卷 205-230页

作者： Angela Ferrari Claus-dieter Munz Bernhard Weigand Institute of Aerodynamics and Gasdynamics University of StuttgartPfaffenwaldring 21D-70569 StuttgartGermany Institute of Aerospace Thermodynamics University of StuttgartPfaffenwaldring 31D-70569 StuttgartGermany

In this paper,a new sharp-interface approach to simulate compressible multiphase flows is *** new scheme consists of a high order WENO finite volume scheme for solving the Euler equations coupled with a high order pathconservative discontinuous Galerkin finite element scheme to evolve an indicator function that tracks the material *** the interface our method applies ghost cells to compute the numerical flux,as the ghost fluid ***,unlike the original ghost fluid scheme of Fedkiw et al.[15],the state of the ghost fluid is derived from an approximate-state Riemann solver,similar to the approach proposed in[25],but based on a much simpler *** formulation leads only to one single scalar nonlinear algebraic equation that has to be solved at the interface,instead of the system used in[25].Away from the interface,we use the new general Osher-type flux recently proposed by Dumbser and Toro[13],which is a simple but complete Riemann solver,applicable to general hyperbolic conservation *** time integration is performed using a fully-discrete one-step scheme,based on the approaches recently proposed in[5,7].This allows us to evolve the system also with time-accurate local time *** to the sub-cell resolution and the subsequent more restrictive time-step constraint of the DG scheme,a local evolution for the indicator function is applied,which is matched with the finite volume scheme for the solution of the Euler equations that runs with a larger time *** use of a locally optimal time step avoids the introduction of excessive numerical diffusion in the finite volume *** different fluids have been used,namely an ideal gas and a weakly compressible fluid modeled by the Tait *** tests have been computed to assess the accuracy and the performance of the new high order scheme.A verification of our algorithm has been carefully carried out using exact solutions as well as a comparison with other numerical re

关键词： Sharp interface capturing compressible multiphase flows one-step time-integration time-accurate local time stepping modified ghost fluid method WENO schemes discontinuous Galerkin methods

On the Identity and Taxonomic Status of Coluber nuthalli Theobald, 1868, with Redescription of the Type Specimens of Coluber nuthalli and Elaphis yunnanensis Anderson, 1879(Reptilia, Squamata, Colubridae)

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Asian Herpetological Research 2015年第1期6卷 1-10页

作者： Klaus dieter SCHULZ Frank TILLACK Abhijit DAS Notker HELFENBERGER An Kuckum5a 52146 Würselen Germany Museum für Naturkunde Leibniz Institute for Evolution and Biodiversity Science Invalidenstrαβe 43 D-10115 Berlin Germany Wildlife Institute of India Chandrabani Dehradun India Kasereistrasse4 9305 Berg SG Switzerland

The taxaColuber nuthalli Theobald, 1868 andElaphis yunnanensis Anderson, 1879 are compared and re-described, based on the examination of their type material. The morphological similarities of these two taxa revealed them as *** yunnanensis Anderson is thus declared as a protected name （nomen conservandum） with priority overC. nuthalli Theobald （nomen oblitum）. A lectotype forElaphis yunnanensis is designated and described. The validity ofyunnanensis as subspecies name in combination withOrthriophis taeniurus （Cope） will be discussed. A key to the subspecies ofO. taeniurus is provided.

关键词： Reptilia Serpentes Colubridae Elaphisyunnanensis Anderson (nomen protectum) Coluber nuthalli Theobald (nomen oblitum) Elapheauct. Orthriophis taeniurus yunnanensis taxonomy morphology China Myanmar

Repeated occurrence of palaeo-wildfires during deposition of the Bahariya Formation(early Cenomanian) of Egypt

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Journal of Palaeogeography 2019年第4期8卷 332-345页

作者： Haytham El Atfy Tarek Anan Andre Jasper dieter Uhl Department of Geology Faculty of ScienceMansoura UniversityMansoura 35516Egypt Programa de Pos-Graduacao em Ambiente e Desenvolvimento PPGADUniversidade do Vale do Taquari UnivatesLajeadoRio Grande do SulBrazil Senckenberg Research Institute and Natural History Museum 60325 Frankfurt am MainGermany Senckenberg Centre for Human Evolution and Palaeoenvironment Tubingen University72076 TubingenGermany

The Upper Cretaceous(early Cenomanian)Bahariya Formation of Egypt has an outstanding reputation for its wealth of vertebrate remains,including a variety of iconic dinosaurs,like the carnivorous Spinosaurus and Carcharodontosaurus,as well as the herbivorous Aegyptosaurus and *** these dinosaur fossils,the Bahariya Formation yielded also a wealth of invertebrate and plant remains,but even today many aspects concerning the continental palaeoenvironments reflected in these deposits(including the occurrence of palaeo-wildfires)have not been studied in *** far six distinct macro-charcoal bearing levels could be identified within the type section of the Bahariya Formation at Gabal El Dist profile,one of the most prolific outcrops of this formation in terms of fossil occurrence located in the north of the Bahariya Oasis,Western Desert,*** of the charcoal investigated by means of SEM originates from ferns,pointing to a considerable proportion of this plant group within the palaeo-ecosystems that experienced *** and(putative)angiosperms have less frequently been *** collected data present evidence that the landscapes at the northern shores of Gondwana repeatedly experienced palaeo-wildfires,adding extra proof to previous statements that the Late Cretaceous was a fiery world on a global scale.

关键词： Bahariya Oasis Gabal El Dist Charcoal Wildfire Dinosaurs Upper Cretaceous Early Cenomanian Egypt

Analytical study of the interface in fibre-reinforced 2D composite material

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Acta Mechanica Sinica 2011年第1期27卷 90-97页

作者： Igor V.Andrianov Jan Awrejcewicz dieter Weichert Department of General Mechanics RWTH Aachen University(TUAachen) Department of Automation and Biomechanics Technical University of Lódz

Imperfect bonding between the constitutive components can greatly affect the properties of the composite *** asymptotic analysis of different types of imperfect interfaces arising in the problem of 2D fibrereinforced composite materials are *** performed study is based on the asymptotic reduction of the governing biharmonic problem into two harmonic *** solutions are obtained in a closed analytical *** obtained results can be used for the calculation of pull-out and pushout tests,as well as for the investigation of the fracture of composite materials.

关键词： Fibre composite material · Asymptotic approach · Weak interface

Tree-ring based PDSI reconstruction since AD 1842 in the Ortindag Sand Land,east Inner Mongolia

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Chinese Science Bulletin 2007年第19期52卷 2715-2721页

作者： LIANG ErYuan SHAO XueMei LIU HongYan ECKSTEIN dieter Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China Institute of Geographic Science and Natural Resource Research Chinese Academy of Sciences Beijing 100101 China College of Environmental Science Peking University Beijing 100871 China Department of Wood Science University of Hamburg Hamburg D-21031 Germany

epartment of Wood Science, University of Hamburg, Hamburg D-21031, GermanyBased on three Chinese pine (Pinus tabulaeformis Carr.) and one Meyer spruce (Picea meyeri Rehd. et Wils.) ring-width chronologies, a 163-year drought history was reconstructed in the eastern Ortindag Sand Land. All tree-ring chronologies show large inter-annual variations and strong common signals and fairly consistent variation between different chronologies, indicating that they are excellent proxy of regional climate. A regional chronology (RC) was established by averaging the four standard chronologies and further employed for the analysis and climatic reconstruction. The analysis revealed that tree growth is primarily limited by low precipitation in February-March and June-July and high temperature in May-July. In addition, RC has high correlations with the monthly Palmer drought severity index (PDSI) prior to and during the growing season because the PDSI considers the accumulation of the droughts. Response function analysis revealed that RC only exhibits significant correlations with the PDSI in June and July (close to the 95% significance level in May). Because May―July is a critical period for tree growth, the average May-July PDSI (PDSI5-7) was reconstructed back to 1842 using RC in the Ortindag Sand Land. The reconstruction can explain 52% of the PDSI variance and the equation was rather stable over time. It agrees well with the variation of the average dryness/wetness indices in North China,and captures the decline process of the East Asian summer monsoon since the mid-1960s. It is worth noting that the Ortindag Sand Land has experienced the most severe drought in the recent 40 years based on the 163-year drought reconstruction. Like summer precipitation in North China the reconstructed PDSI5-7 also displays a 20-year oscillation.

关键词：干旱沙地环境地质

Seamless and non-repetitive 4D texture variation synthesis and real-time rendering for measured optical material behavior

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Computational Visual Media 2019年第2期5卷 161-170页

作者： Martin Ritz Simon Breitfelder Pedro Santos Arjan Kuijper dieter W. Fellner Fraunhofer IGD Darmstadt64283Germany TU Darmstadt Darmstadt64289Germany TU Graz Graz8010Austria

We show how to overcome the single weakness of an existing fully automatic system for acquisition of spatially varying optical material behavior of real object surfaces. While the expression of spatially varying material behavior with spherical dependence on incoming light as a 4D texture(an ABTF material model) allows flexible mapping onto arbitrary 3D geometry, with photo-realistic rendering and interaction in real time,this very method of texture-like representation exposes it to common problems of texturing, striking in two disadvantages. Firstly, non-seamless textures create visible artifacts at boundaries. Secondly, even a perfectly seamless texture causes repetition artifacts due to their organised placement in large numbers over a 3D surface. We have solved both problems through our novel texture synthesis method that generates a set of seamless texture variations randomly distributed over the surface at shading time. When compared to regular 2D textures, the inter-dimensional coherence of the 4D ABTF material model poses entirely new challenges to texture synthesis, which includes maintaining the consistency of material behavior throughout the 4D space spanned by the spatial image domain and the angular illumination hemisphere. In addition, we tackle the increased memory consumption caused by the numerous variations through a fitting scheme specifically designed to reconstruct the most prominent effects captured in the material model.

关键词： optical material behavior reflectance modeling 4D texture synthesis texturing

An Assessment Tool for Land Reuse with Artificial Intelligence Method

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International Journal of Automation and computing 2010年第1期7卷 1-8页

作者： dieter D. Genske Dongbin Huang Ariane Ruff Institute of Architecture and Planning University of Liechtenstein Fiirst-Franz-Josefstrasse Vaduz LI 9490 Liechtenstein Institute for Environmental Decisions ETH Zurich Universitaetstrasse 22 Zurich CH 8092 Switzerland Fachhochschule Nordhausen Weinberghof 4 Nordhausen D-99734 Germany

This paper focuses on land resource consumption due to urban sprawl. Special attention is given to shrinking regions, characterized by economic decline, demographic change, and high unemployment rates. In these regions, vast terrain is abandoned and falls derelict. A geographic information system （GIS） based multi-criteria decision tool is introduced to determine the reuse potential of derelict terrain, to investigate the possible reuse options （housing, business and trade, industry, services, tourism and leisure, and re-greening）, and to visualize the best reuse options for groups of sites on a regional scale. Achievement functions for attribute data are presented to assess the best reuse options based on a multi-attribute technique. The assessment tool developed is applied to a model region in Germany. The application of the assessment tool enables communities to become aware of their resources of derelict land and their reuse potential.

关键词： Decision support system land assessment geographic information system (GIS) sustainable development artificial intelligence.

Numerical Modelling of Seismic Site Effects Incorporating Non-linearity and Groundwater Level Changes

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Journal of Earth Science 2010年第6期21卷 931-940页

作者： Dominik Ehret Joachim Rohn dieter Hannich Carlos Grandas Gerhard Huber Department of Applied Geology University of Erlangen-Nuremberg Department of Applied Geology University (TH) of Karlsruhe Institute of Soil and Rock Mechanics University (TH) of Karlsruhe

In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions （especially of the uppermost unconsolidated units）, information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach ean be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account.

关键词： microzonation site effect visco-hypoplasticity non-linearity Bucharest Romania.