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Investigation of time dependent development of soil structure and formation of macropore networks as affected by various precrop species

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International Soil and Water Conservation Research 2014年第2期2卷 51-66页

作者： Sebastian K.Pagenkemper Daniel Uteau Puschmann stephan peth Rainer Horn Dept.of Soil Science Institute of Plant Nutrition and Soil ScienceUniversity of KielGermany Dept.of Soil Science Organic Agriculture SciencesUniversity of KasselGermany

A well developed macropore network is advantageous in terms of transport processes regarding gas and water,as well as nutrient acquisition and root growth of crops.X-ray computed tomography provides a non-destructive method to visualize and quantify three-dimensional pore *** and morphological parameters of the complex pore system such as connectivity,tortuosity,porosity and pore surface area would be very useful for modeling and simulation of transport and exchange processes by providing quantitative data on relevant soil structural features and their modification by soil *** scope of this study was to analyze and quantify the development of soil structure in the subsoil depending on three different precrop species(alfalfa A,chicory C and fescue F),at three depths(45,60 and 75 cm)and cultivation periods(1,2 and 3 years).Furthermore,morphological(air-filled porosityθa,pore surface area)and geometrical(pore diameter,connectivity,continuity,tortuosityτ)parameters were gathered with X-ray CT and image *** an experimental field trial(Germany)with a Haplic Luvisol as soil type samples were taken and ***-capacity(θa)was measured in the laboratory for the same cylinders and compared to the results derived by image ***-capacity was highest for alfalfa(3 years,75 cm).Tortuosity(τ)ranged between 1.3 and 4.38,while alfalfa(3 years)showed the highest value,which indicated structural development due to crack formation by enhanced root water ***,an increase in accessible surface may improve water and nutrient supply for plants,whereas the highτvalues may assume that oxygen supply is *** was found that the interaction of gas-diffusivity and the calculated parameters should be further investigated in terms of limitations to plant growth.

关键词： Biological tillage Image analysis Batch processing Subsoil structure Dynamic development

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放牧对内蒙古大针茅草原土壤剪切力空间分布的影响

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草业科学 2014年第2期31卷 219-223页

作者：甘磊彭新华谢永雄钟家尚 stephan peth Rainer HORM 桂林理工大学广西矿冶与环境科学实验中心广西桂林541004 桂林理工大学环境科学与工程学院广西桂林541004 土壤与农业可持续发展国家重点实验室中国科学院南京土壤研究所江苏南京210008 Institute of Plant Nutrition and Soil Science Christian-Albrechts-University zu Kiel

本研究在内蒙古草原生态系统研究站的持续放牧(CG)和禁牧(UG79,从1979年开始禁牧)两个试验区。利用GPS在每个区分别设立1个长135m×105m的样地,每样地选100个测量点,利用Hand-held vane tester测量土壤剪切力并研究其空间分布情况。结... 详细信息

本研究在内蒙古草原生态系统研究站的持续放牧(CG)和禁牧(UG79,从1979年开始禁牧)两个试验区。利用GPS在每个区分别设立1个长135m×105m的样地,每样地选100个测量点,利用Hand-held vane tester测量土壤剪切力并研究其空间分布情况。结果表明,CG区,放牧导致土壤孔隙减少,容重增加,有机质减少,土壤剪切力高于凋落物与有机质较多的禁牧小区。在UG79和CG两个区,从干旱条件到中等水分条件,土壤剪切力空间分布都有差异,说明土壤含水量在一定程度上决定了土壤剪切力的空间分布,但到达湿润条件后,其分布有恢复原状的趋势,这暗示土壤水分对其影响也存在限制。

关键词：放牧土壤剪切力空间分布土壤水分

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(Not) an elementary question:How to mobilize the iron in the wall?

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Molecular Plant 2021年第10期14卷 1610-1611页

作者： stephan Clemens Department of Plant Physiology and Faculty of Life Sciences:Food Nutrition and HealthUniversity of BayreuthUniversitätsstrasse 3095440 BayreuthGermany

Photosynthesis,respiration,and countless other processes are dependent on proteins that carry iron(Fe)as an essential *** Fe was recruited for biological functions early in evolution,it was an available *** Earth's at... 详细信息

关键词： element. elementary sulfide

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Roots dOdge streSs

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Molecular Plant 2023年第12期16卷 1885-1886页

作者： stephan Clemens Department of Plant Physiology University of BayreuthUniversitatsstrasse 3095440BayreuthGermany

A hallmark of plant development is *** system architecture modulation in response to fluctuations of nutrient and water supply is a case in point(Giehl et al.,2014).The formation and length of lateral roots or the density of root hairs are strongly influenced by the availability of macro-and *** actively forage for mineral-rich patches in the typically heterogeneous soil environment and adjust their development systemically to increase the surface for nutrient ***,the opposite can happen as well.A recent study by Wang et al.(2023)convincingly demonstrated an active avoidance of unfavorable conditions by rice *** the seminal root of rice seedlings was placed between two agar blocks,one of them containing cations at toxic concentrations,adventitious roots developed only on the non-stress side,while development on the stress side was arrested(Figure 1).Besides,far more lateral roots were formed than in the absence of asymmetrically applied *** a while,this resulted in a total root biomass equivalent to that of control *** roots,in other words,had successfully shifted away from the stressful environment.

关键词： soil roots Figure

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On combinatorial Gauss-Bonnet Theorem for general Euclidean simplicial complexes

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Frontiers of Mathematics in China 2016年第5期11卷 1345-1362页

作者： stephan KLAUS Scientific Administrator of the MFO and Adjunct Professor at Mainz University Mathematisches Forschungsinstitut Oberwolfach gGmbH (MFO) Schwarzwaldstrasse 9-11 D-77709 Oberwolfach-Walke Germany

For a finitely triangulated closed surface M2, let αx be the sum of angles at a vertex x. By the well-known combinatorial version of the 2- dimensional Gauss-Bonnet Theorem, it holds ∑x（2π- αx） =2αχ（M^2）, where X denotes the Euler characteristic of M^2, αx denotes the sum of angles at the vertex x, and the sum is over all vertices of the triangulation. We give here an elementary proof of a straightforward higher-dimensional generalization to Euclidean simplicial complexes K without assuming any combinatorial manifold condition. First, we recall some facts on simplicial complexes, the Euler characteristics and its local version at a vertex. Then we define δ（τ） as the normed dihedral angle defect around a simplex τ. Our main result is ∑τ（-1）^dim（τ）δ（τ） = χ（K）, where the sum is over all simplices τ of the triangulation. Then we give a definition of curvature k（x） at a vertex and we prove the vertex-version ∑x∈K0 k（x） = χ（K） of this result. It also possible to prove Morse-type inequalities. Moreover, we can apply this result to combinatorial （n ＋ 1）-manifolds W with boundary B, where we prove that the difference of Euler characteristics is given by the sum of curvatures over the interior of W plus a contribution from the normal curvature along the boundary B： χ（W）- 1/2 χ（B） = ∑τ∈W-B（-1）^dim（τ）δ（τ）＋ ∑τB（-1）^dim（τ）ρ（τ）.

关键词： Curvature dihedral angle Euclidean simplex triangulation Euler characteristic Euler manifold combinatorial manifold pseudo manifold

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A two dimensional Euler-Lagrangian model of wood gasification in a charcoal bed-Part II： Parameter influence and comparison

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Particuology 2017年第6期15卷 22-30页

作者： stephan Gerber Michael Oevermann Freie Universitat Berlin Arnimallee 6 14195 Berlin Germany Chalmers University of Technology Department of Applied Mechanics Division of Combustion Gothenburg Sweden

A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle-particle and particle-wall colli- sions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study （Gerber ＆ Oevermann, 2014）. The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with differ- ent sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle-particle and particle-wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reac- tor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.

关键词： Wood gasification simulation Gas-solid flow Discrete element method Pyrolysis Gasification Charcoal

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Horn–Schunck optical flow applied to deformation measurement of a birdlike airfoil

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Chinese Journal of Aeronautics 2015年第5期28卷 1305-1315页

作者： Gong Xiaoliang stephan Bansmer School of Aeronautics Northwestern Polytechnical University Institute of Fluid Mechanics Technische Universitt Braunschweig

Current deformation measurement techniques suffer from limited spatial resolution. In this work, a highly accurate and high-resolution Horn Schunck optical flow method is developed and then applied to measuring the static deformation of a birdlike flexible airfoil at a series of angles of attack at Reynolds number 100,000 in a low speed, low noise wind tunnel. To allow relatively large displacements, a nonlinear Horn-Schunck model and a coarse-to-fine warping process are adopted. To preserve optical flow discontinuities, a nonquadratic penalization function, a multi- cue driven bilateral filtering and a principle component analysis of local image patterns are used. First, the accuracy and convergence of this Horn-Schunck technique are verified on a benchmark. Then, the maximum displacement that can be reliably calculated by this technique is studied on synthetic images. Both studies are compared with the performance of a Lucas-Kanade optical flow method. Finally, the Horn-Schunck technique is used to estimate the 3-D deformation of the birdlike airfoil through a stereoscopic camera setup. The results are compared with those computed by Lucas-Kanade optical flow, image correlation and numerical simulation.

关键词： Deformation measurementsFlexible airfoil Horn-Schunck Optical flow Stereoscopic

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Proterozoic tectonothermal processes imaged with magnetotellurics and seismic reflection in southern Australia

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Geoscience Frontiers 2020年第3期11卷 885-893页

作者： Tom Wise stephan Thiel Geological Survey of South Australia Department for Energy and MiningAdelaideSA5005Australia School of Earth and Environmental Sciences University of AdelaideAdelaideSA5005Australia

Over the last two decades,co-located seismic and magnetotelluric(MT) profiles provided fundamental geophysical data sets to image the Australian *** their complimentary nature,the data are processed and often interpreted separately without common processes in *** here qualitatively compare 2 D resistivity inversion models derived from MT and seismic reflection profiles across a region of Archean-Proterozoic Australia to address the causes of variations in seismic response and anomalous conductivity in the *** find that there exists a spatial association between regions of low reflectivity in seismic sections and low resistivity in co-located2 D MT modelled *** relationships elucidate possible signatures of past magmatic and fluid-related *** on their diffuse or discrete character,we hypothesize these signatures signify fossil melting of the crust due to mafic underplating,magma movement or hydrothermal fluid flow through the *** approach discussed herein is a process-oriented approach to interpretation of geophysical images and a significant extension to traditional geophysical methods which are primarily sensitive to a singular bulk rock property or state.

关键词： Magnetotellurics Seismic reflection Resistivity

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Flow frictional characteristics of microencapsulated phase change material suspensions flowing through rectangular minichannels

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Science China(Technological Sciences) 2006年第4期49卷 445-456页

作者： Frank Dammel Peter stephan Chair of Technical Thermodynamics Darmstadt University of Technology Germany

An experimental investigation was conducted on the laminar flow frictional characteristics of suspensions with microencapsulated phase change material (MEPCM) in water flowing through rectangular copper minichannels. The MEPCM was provided at an average particle size of 4.97 μm, and was mixed with distilled water to form suspen- sions with various mass concentrations ranging from 0 to 20%. The experiment was per- formed to explore the effect of MEPCM mass concentration on friction factor and pressure drop in the minichannels. The Reynolds number ranged from 200 to 2000 to provide laminar and transitional flows. It was found that the experimental data for the suspensions with 0 and 5% concentration agree well with the existing theoretical data for an incom- pressible, fully developed, laminar Newtonian flow. For the suspensions with mass con- centrations higher than 10%, there is an obvious increase in friction factor and pressure drop in comparison with laminar Newtonian flow.

关键词： microencapsulated phase change material suspension, friction factor, rectangular minichannel.

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Land Monitoring Network Services based on international geospatial standards:SOSI and geoland2/SDI Projects

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International Journal of Digital Earth 2010年第S01期3卷 70-84页

作者： stephan Meissl Gerhard Triebnig EOX IT Services GmbH Thurngasse 8/41090 WienAustria

Spatial Observation Services and Infrastructure is a project to develop and verify innovative infrastructure and services within the context of land monitoring and Earth Observation initiatives at European and Member State(MS)*** project’s results contribute to the concept definition of the Shared Environmental Information System(SEIS)emphasising symmetrical online sharing of information as opposed to unidirectional *** a pre-operational set-up,involving the European Environment Agency(EEA),four MS sites and the European Space Agency(ESA),a decentralised information system respecting the Infrastructure for Spatial Information in Europe(INSPIRE)principles is demonstrated integrating distributed data and processing services as well as interactive multi-lingual *** geoland2 project is carried out in the context of Global Monitoring for the Environment and Security(GMES),a joint initiative of the European Commission and ESA,aiming to build up a European capacity for *** Spatial Data Infrastructure(SDI)task shall set up operational services for the discovery,viewing,access and delivery of all products generated in the geoland2 *** paper presents the projects along the five International Standards Organisation(ISO)/Reference Model of Open Distributed Processing viewpoints and concludes with the main recommendation that service provisioning can strongly benefit from a(re-)utilisation of the Service Support Environment(SSE)technology provided sustainably by ESA and from the related rich experience.

关键词： geoland2 SOSI INSPIRE GMES environment monitoring satellite Earth Observation

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