检索结果-南通市图书馆

Viscoelasticity and shear resistance at the aggregate scale of structured and organic carbon-free Chernozems

Pedosphere 2023年第5期33卷 754-764页

作者： Christoph HAAS rainer HORN Philipp SAGGAU rainer DUTTMANN Institute for Plant Nutrition and Soil Science University of KielKiel 24118Germany Department of Geography Division of Landscape Ecology and Geoinformation SciencesUniversity of KielKiel 24118Germany

Soil rheology characterises the flow behaviour of soils at the particle-particle to aggregate *** sweep tests(ASTs)are often the method of choice for parameterizing soil flow properties,such as the shear strain values at the end of the linear viscoelastic range(i.e.,the deformation is mainly elastic)and at the yield point(i.e.,elastic equals plastic deformation).Samples from seven soil profiles and five soil depths of Chernozems,collected in the Maidanetske study area,close to Uman City of Ukraine,were analysed to evaluate the effect of soil organic carbon(SOC)on the parameters related to soil microstructural stability derived from *** organic carbon was removed with H_(2)O_(2)to determine the soil texture-dependent values of soil rheological properties,which were compared to the values determined for samples with intact water-stable *** shear resistance-related parameters increased for aggregated soil samples compared to SOC-free soil samples,indicating an increase in soil stability due to *** contrast,the values of the overall viscoelasticity and the shear strain were reduced for aggregated soil samples,indicating decreased soil *** functions were applied to predict the shear strain-dependent loss and storage moduli and shear stress values as a function of SOC *** particles(630–2000μm)and volumetric water content improved the *** conclude that increased SOC content,through the gluing and cementing effects of SOC and altered aggregate shapes compared to SOC-free soil materials,contributes to higher microstructural ***,the increased water content in the SOC-containing soil samples reversed soil strengthening *** was due to the fact that a more rapid increase in positive water pressure under shear stress weakened the samples and the spherical aggregates began to rotate more easily,thus loosing energy,when compared to platy particles of the SOC-free soil materials.

关键词： aggregation rheology shear strain shear stress soil organic carbon depletion soil stability

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Shock Wave Smearing by Passive Control

引用

Journal of Thermal Science 2006年第1期15卷 43-47,42页

作者： Piotr DOERFFER Oskar SZULC rainer BOHNING IMP PAN Fiszera 14 PL-80 952 Gdansk Poland ISL Universitat Karlsruhe Karlsruhe Germany

Normal shock wave, terminating a local supersonic area on an airfoil, limits its performance and becomes a source of high speed impulsive noise. It is proposed to use passive control to disintegrate the shock wave. Details of the flow structure obtained by this method are studied numerically. A new boundary condition has been developed and the results of its application are verified against experiments in a nozzle flow. The method of shock wave disintegration has been confirmed and detailed analysis of the flow details is presented. The substitution of a shock wave by a gradual compression changes completely the source of the high speed impulsive noise and bears potential of its reduction.

关键词： transonic flows shock wave boundary layer interaction passive control.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Insights into ligand expression heterogeneity across multiple cell types in the adult forebrain that regulates neural stem cell behavior

引用

Neural Regeneration Research 2019年第8期14卷 1369-1371页

作者： rainer Akkermann Kasum Azim Department of Neurology and Neuroregeneration Medical FacultyHeinrich-Heine-University

In the adult mammalian central nervous system (CNS), neural cell generation is restricted to two highly specialized germinal niches. These are the subventricular zone (SVZ) that borders the forebrain lateral ventricles and the subgranular zone of the hippocampus. In the case of the former niche, the SVZ gives rise daily to thousands of migratory neuroblasts that travel long distances to the olfactory bulb via the rostral migratory stream. Neural stem cells (NSCs) first engage through a sequence of activation phe no types and give rise to transiently amplifying progenitors (TAPs) that subsequently differentiate into neuroblasts. Once in the olfactory bulb, they generate phenotypically distinct neurons. Most of these constitute the interneuron class that is preferentially derived from the lateral portion of the SVZ, whilst a small proportion of projection neurons are also formed from the dorsal SVZ.

关键词： Insights ligand expression cell behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Biochar-Induced Changes in Soil Resilience:Effects of Soil Texture and Biochar Dosage

引用

Pedosphere 2017年第2期27卷 236-247页

作者： Ayodele Ebenezer AJAYI rainer HORN Department of Agricultural and Environmental Engineering Federal University of Technology 340252 Akure Ondo State (Nigeria) Institute for Plant Nutrition and Soil Science CAU Kiel 24118 Kiel (Germany)

Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended ***, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro-and macro-structural stability, and resilience of two differently textured soils,fine sand(FS) and sandy loam(SL). Test substrates were prepared by adding 50 or 100 g kg^(-1) biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.

关键词： aggregate stability amendment material compressive strength rheometry shear properties total porosity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The enhanced element enrichment in the supercritical states of granite–pegmatite systems

引用

Acta Geochimica 2019年第3期38卷 335-349页

作者： rainer Thomas Paul Davidson Karen Appel Section 3.6.Chemistry and Physics of Earth Materials Helmholtz-Centre Potsdam German Research Centre for Geoscience – GFZ CODES Centre for Ore Deposit and Earth Sciences School of Natural Sciences University of Tasmania High Energy Density scientific instrument European X-Ray Free-Electron Laser Facility GmbH

In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.

关键词： Granites Pegmatites Supercritical state Extreme element enrichment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamical Analysis of Sputtering at Threshold Energy Range： Modelling of Ar＋Ni（100） Collision System

引用

Chinese Physics Letters 2008年第2期25卷 730-733页

作者： HUNDUR Yakup GUVENC Ziya B HIPPLER rainer Department of Physics Istanbul Technical University Istanbul TR-34469 Turkey Electronic and Communication Engineering Cankaya University Balgat Ankara TR-06530 Turkey Institut für Physik Ernst-Moritz-Arndt Universitate Greifswald Greifswald D-17489 Germany

The sputtering process of Ar＋Ni（100） collision systems is investigated by means of constant energy molecular dynamics simulations. The Ni（100） slab is mimicked by an embedded-atom potential, and the interaction between the projectile and the surface is modelled by using the reparametrized ZBL potential. Ni atom emission from the lattice is analysed over the range of 20-50 eV collision energy. Sputtering yield, angular and energy distributions of the scattered Ar and of the sputtered Ni atoms are calculated, and compared to the available theoretical and experimental data.

关键词： SURFACE YIELD

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effects of elevated pO_3 on carbon cycle between above andbelowground organs of trees

引用

Journal of Environmental Sciences 2006年第5期18卷 932-936页

作者： LIU Xi-ping Rennenberg Heinz Matyssek rainer College of Life Sciences Northwest Sci-Tech University of Agriculture and Forestry Yangling 712100 China Institute of Forest Botany and Tree Physiology University Freiburg D-79110 Freiburg Germany Department of Ecopogy/Ecophysiology of Plants Technical University Munich D-85354 Freising Germany

Translocation of carbohydrate from leaves to roots via phloem and reallocation from roots to leaves via xylem regulate the allocation of carbon （C） between above and belowground organs of trees. To quantitatively analyze effects of elevated ozone concentrations pO3 on the internal cycle of C, juvenile beech and spruce were grown in phytotrons and exposed to ambient and elevated pO3 （i.e. twice-ambient O3 levels, restricted to 〈 150 ppb） for two growing seasons. The translocation of C in the phloem and xylem was quantitatively studied by investigating the phloem/xylem-loading of sugars, the differentiation of stem conductive tissue and the hourly water flow through the stem. Results in the present study shown, elevated pO3 significantly decreased C translocation from shoot to roots in beech by reducing both sugar concentration in the phloem and conductive phloem area. Elevated pO3 also significantly decreased C reallocation from the roots to the shoot in beech by reducing both of sugar concentration in the xylem and transpiration rate. The adverse effects of elevated pO3 on C translocation in the phloem and xylem, however, were small in spruce. Contrasting to beech, spruce is less sensitive to elevated pO3, regarding to phloem differentiation and sugar concentrations in the phloem and xylem.

关键词： beech carbon cycle elevated pO3 phloem spruce xylem

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

＂All Happy Families＇： The Sopranos and Television Culture in the Twenty-First Century

引用

Frontiers of Literary Studies in China-Selected Publications from Chinese Universities 2016年第3期10卷 474-494页

作者： rainer Winter Institute of Media and Communications Faculty of Cultural Sciences Alpen-Adria UniversitaetKlagenfurt 9020 Klagenfurt Austria

Since the 1980s, Cultural Studies have analyzed television in the context of the present. They have asked how soap operas and TV series contribute to the circulation of meanings and pleasures in everyday contexts. John Fiskes coined the concept television culturein his very successful book with the same title Taking The Sopranos as an example, this article shows that quality TV is an outstanding contribution to television culture. The show is more complex, more layered and more intertextual than the shows of the 1980s that Fiske interpreted. The Sopranos is a postmodern cultural phenomenon that appeals to different groups of viewers. It is no longer only about the addicted fans, but also about critical viewers who want to better understand themselves and their lives, and also about connoisseurs and art enthusiasts to whom serial reception becomes a distinctive feature. This article comes to the conclusion that popular culture in the sense of Cultural Studies is still of important political significance in the twenty-first century.

关键词： Cultural Studies television culture quality TV The Sopranos,popular culture media studies narrative structure intertextuality

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Performance analysis of parallel gravitational N-body codes on large GPU clusters

引用

Research in Astronomy and Astrophysics 2016年第1期16卷 89-100页

作者： Si-Yi Huang rainer Spurzem Peter Berczik National Astronomical Observatories and Key Laboratory of Computational Astrophysics Chinese Academy of Sciences Beijing 100012 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing 100871 China Main Astronomical Observatory Ukrainian National Academy of Sciences 03680 Kiev Ukraine Astronomisches Rechen-Institut Zentrum fur Astronomie Universitat Heidelberg 69120 Heidelberg Germany

We compare the performance of two very different parallel gravitational N-body codes for astrophysical simulations on large Graphics Processing Unit（GPU） clusters, both of which are pioneers in their own fields as well as on certain mutual scales- NBODY6＋＋ and Bonsai. We carry out benchmarks of the two codes by analyzing their performance, accuracy and efficiency through the modeling of structure decomposition and timing measurements. We find that both codes are heavily optimized to leverage the computational potential of GPUs as their performance has approached half of the maximum single precision performance of the underlying GPU cards. With such performance we predict that a speed-up of200- 300 can be achieved when up to 1k processors and GPUs are employed simultaneously. We discuss the quantitative information about comparisons of the two codes, finding that in the same cases Bonsai adopts larger time steps as well as larger relative energy errors than NBODY6＋＋, typically ranging from10- 50 times larger, depending on the chosen parameters of the codes. Although the two codes are built for different astrophysical applications, in specified conditions they may overlap in performance at certain physical scales, thus allowing the user to choose either one by fine-tuning parameters accordingly.

关键词： methods: analytical -- methods: data analysis -- methods: numerical

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Climate Change, Risk and Grain Yields in China

引用

Journal of Integrative Agriculture 2013年第7期12卷 1279-1291页

作者： rainer Holst Xiaohua Yu Carola Grün Courant Research Center 'Poverty Equity and Growth' Georg-August-University of Goettingen World Bank

Adopting Just and Pope （1978, 1979） style yield functions, this paper proposes a method to analyze the impacts of regional climate change on grain production in China. We find that changes in climate will affect grain production in North and South China differently. Specifically, it emerges that a 1℃ increase in annual average temperature could reduce national grain output by 1.45% （1.74% reduction in North China and 1.19% reduction in South China）, while an increase in total annual precipitation of around 100 mm could increase national grain output by 1.31% （3.0% increase in North China and 0.59% reduction in South China）.

关键词： grain yield climate change yield risk China

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：