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A-posteriori error estimation for second order mechanical systems

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Acta Mechanica Sinica 2012年第3期28卷 854-862页

作者： Thomas Ruiner j.rg Fehr Bernard Haasdonk Peter Eberhard Institute of Engineering and Computational Mechanics University of StuttgartPfaffenwaldring 970569 StuttgartGermany Institute of Applied Analysis and Numerical Simulation University of StuttgartPfaffenwaldring 5770569 StuttgartGermany

One important issue for the simulation of flexible multibody systems is the reduction of the flexible bodies de- grees of freedom. As far as safety questions are concerned knowledge about the error introduced by the reduction of the flexible degrees of freedom is helpful and very important. In this work, an a-posteriori error estimator for linear first order systems is extended for error estimation of me- chanical second order systems. Due to the special second order structure of mechanical systems, an improvement of the a-posteriori error estimator is achieved. A major advan- tage of the a-posteriori error estimator is that the estimator is independent of the used reduction technique. Therefore, it can be used for moment-matching based, Gramian matrices based or modal based model reduction techniques. The capability of the proposed technique is demon- strated by the a-posteriori error estimation of a mechanical system, and a sensitivity analysis of the parameters involved in the error estimation process is conducted.

关键词： A-posteriori error estimator. Flexible multibodysystems Model reduction

Preliminary Mapping and Characterisation of Soils in the Pirin Mountains (Bulgaria)

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journal of Mountain Science 2008年第2期5卷 122-129页

作者： Maika Lβiger j.rg Scheithauer Karsten Grunewald University of Technology Dresden D-01062 Dresden Germany Landscape Research Centre Dresden Am Ende 14 D-01277 Dresden Germany

Soil types, humus types and vegetation as well as their hypsometric variation were analysed in terms of sequences in the northern part of the high mountains of the Pirin National Park at altitudes between looo and 2400 m a.s.1. The study area is characterised by a large variety of natural parameters like petrology （mainly marble and granite）, morphology （different slope deposits, exposition） and the orographic climate gradient. Statistical analyses using these parameters provided a basis for the soil group classification of the sites. Based on a Digital Terrain Model （DTM） and a geological map of the Pirin National Park, the results of these statistical analyses were used to generate a ＂map of potential soil groups＂（regionalisation using GIS）. Six potential soil groups could be determined. The resulting map exhibits a confidence level of 68 % on 74.4 % of the covered area. Rendzic Leptosols, in combination with Folic Histosols and Histi-lithic Leptosols occur in the alpine and subalpine regions on calcareous substrates. With decreasing altitude they are replaced by a mosaic of Rendzic Leptosols, Phaeozems and an increasing occurrence of Cambic Umbrisols. Umbrisols found on silicatic substrates in the alpine region are replaced by Cambic Umbrisols with decreasing altitude as well. Hence, pedogenesis is characterised by increasing browning and depth of the soil profiles with decreasing altitude. The pH-level is slightly acidic to neutral in lower zones and on calcareous rocky bases. Acidification increases in the subalpine zone. Soil pH decreases down to 4 on silicate subtrates. Typical humic values in mineral topsoils are 10 to 12 %, and in organic layers of the soils above 2000 m a.s.1, they are even more. The C：N ratio closely ranges around 20 （median）.

关键词： Cluster analysis soil mapping hypsometric soil differentiation Southeast Europe

Palliative cardia resection with gastroesophageal reconstruction for perforated carcinoma of the gastroesophageal junction

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World journal of Gastroenterology 2009年第24期15卷 3065-3067页

作者： Sonja Gillen Helmut Friess j.rg Kleeff Department of Surgery Technische Universitt München

Iatrogenic perforation of esophageal cancer or cancer of the gastroesophageal(GE)junction is a serious complication that,in addition to short term morbidity and mortality,significantly compromises the success of any subsequent oncological ***,we present an 82-year-old man with iatrogenic perforation of adenocarcinoma of the GE *** surgical intervention included palliative resection and GE *** the case of iatrogenic tumor perforation, the primary goal should be adequate palliative(and not oncological)*** different approaches for iatrogenic perforation,*** versus endoscopic therapy are discussed.

关键词： Esophageal cancer Esophageal perforation Emergency surgery Stent therapy

Metabolic Control of Chloroplast Gene Expression： An Emerging Theme

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Molecular Plant 2017年第1期10卷 1-3页

作者： Alexandra-Viola Bohne j.rg Nickelsen Department Biology I Molecular Plant Sciences LMU Munich Grosshaderner Strasse 2-4 82152 Planegg-Martinsried Germany

In all organisms, regulation of gene expression plays an essential part in acclimation to changes in the environment and the meta-bolic status of cells. However, little is known about the mecha-nisms by which nutritio... 详细信息

关键词： Control Expression Theme

Cast iron-a predictable material

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China Foundry 2011年第1期8卷 51-61页

作者： j.rg C.Sturm Guido Busch MAGMA Gieβereitechnologie GmbH

High strength compacted graphite iron (CGI) or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train *** mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron *** products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast *** the last 20 years,casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of *** support of the feeding related layout of the casting is still one of the most important duties for casting process *** on the alloy poured,different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free ***,it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature *** be able to quantitatively predict these defects,solidification simulation had to be combined with density and mass transport calculations,in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding *** cast iron foundries,the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes,especially since the influence of alloying elements,melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast *** allows the prediction of local structures,phases and ultimately the local mechanical properties of cast irons,to asses casting quality in the foundry but also to make use of this quantitative information during design of the *** quality issues related to thermally driven stresses in castings are also gaining inc

关键词： casting process simulation cast iron defects casting performance development

A machine learning approach to model solute grain boundary segregation

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npj Computational Materials 2018年第1期4卷 130-137页

作者： Liam Huber Raheleh Hadian Blazej Grabowski j.rg Neugebauer Max-Planck-Institut für Eisenforschung GmbH D-40237 DüsseldorfGermany

Even minute amounts of one solute atom per one million bulk atoms may give rise to qualitative changes in the mechanical response and fracture resistance of modern structural *** changes are commonly related to enrichment by several orders of magnitude of the solutes at structural defects in the host *** underlying concept—segregation—is thus fundamental in materials *** include it in modern strategies of materials design,accurate and realistic computational modelling tools are ***,the enormous number of defect configurations as well as sites solutes can occupy requires models which rely on severe *** the present study we combine a high-throughput study containing more than 1 million data points with machine learning to derive a computationally highly efficient framework which opens the opportunity to model this important mechanism on a routine basis.

关键词： grain solute boundary

A user perspective on future cloud-based services for Big Earth data

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International journal of Digital Earth 2021年第12期14卷 1758-1774页

作者： julia Wagemann Stephan Siemen Bernhard Seeger j.rg Bendix Laboratory of Climatology and Remote Sensing(LCRS) Faculty of GeographyUniversity of Marburg Forecast Department European Centre for Medium-Range Weather Forecasts(ECMWF) Department of Mathematics and Computer Science University of Marburg

Cloud-based services introduce a paradigm shift in how users access,process and analyse Big Earth data.A key challenge is to align the current state of how users access,process and analyse the data with trends and roadmaps large data organisations *** addition,due to the increased availability of open data,a more diverse user base wants to take advantage of Earth science data leading to new user *** run a web-based survey among Big Earth data users to better understand the motivation to migrate to cloud-based services as well as the challenges and opportunities that might *** show an overall interest in moving to cloud-based services but air an insufficient literacy in cloud systems and a lack of trust due to security concerns and opacity of emerging *** gaps demand efforts on three ***,cloud services shall be targeted at intermediate users instead of policy-and decision-makers and over-engineered systems with a high level of abstraction should be ***,more substantial capacity-building efforts are required to decrease the existing gap in cloud skills and ***,a cloud certification mechanism could help in building up overall trust in cloud-based services.

关键词： User requirements cloudbased services Big Earth data open data

Recent weakening of seasonal temperature difference in East Asia beyond the historical range of variability since the 14th century

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Science China Earth Sciences 2023年第5期66卷 1133-1146页

作者： jianglin WANG Bao YANG Zhiyuan WANG j.rg LUTERBACHER Fredrik Charpentier LjUNGQVIST Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China School of Geography and Ocean Science Nanjing UniversityNanjing210023China College of Geography and Environmental Science Zhejiang Normal UniversityJinhua321004China Science and Innovation Department World Meteorological Organization(WMO)Geneva1211Switzerland Department of History Stockholm UniversityStockholm10691Sweden Bolin Centre for Climate Research Stockholm UniversityStockholm10691Sweden Swedish Collegium for Advanced Study LinneanumThunbergsvägen 2Uppsala75238Sweden

Seasonal differences of temperature are crucial components of the Earth's climate ***,the relatively short observational record,especially for East Asia,has limited progress in understanding seasonal *** this study,we identify ten tree-ring chronologies separately correlated with local winter(December-February)temperatures and twelve different tree-ring chronologies separately correlated with summer(june-August)temperatures across East *** these discrete seasonal tree-ring chronologies,we develop two independent winter and summer temperature reconstructions covering the period 1376-1995 CE for East Asia,and compare them with model *** reconstructions show a more significant volcanic cooling and earlier onset of modern warming in summer than in *** reconstructed summer-minus-winter temperature decreased since as early as the late 19th century,which has driven the current state of seasonal temperature difference to out of the natural variability since the *** models could generally reproduce the variability and trends in seasonal reconstructions,but might largely underestimate seasonal differences due to the fact that seasonal expressions on external forcing and modes of internal variability are too *** study highlights the importance of using proxy-based seasonal reconstructions to evaluate the performance of climate models,and implies a substantial weakening of seasonal temperature differences in the future.

关键词： Seasonal temperature differences Temperature reconstruction East Asia Tree rings Recent warming

Device-assisted enteroscopy: A review of available techniques and upcoming new technologies

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World journal of Gastroenterology 2019年第27期25卷 3538-3545页

作者： Markus Schneider j.rg Höllerich Torsten Beyna Department of Internal Medicine and Gastroenterology Evangelisches Krankenhaus Düsseldorf

The advent of video capsule endoscopy into clinical routine more than 15 years ago led to a substantial change in the diagnostic approach to patients with suspected small bowel diseases, often indicating a deep enteroscopy procedure for diagnostical confirmation or endoscopic treatment. Device assisted enteroscopy was developed in 2001 and for the first time established a practicable, safe and effective method for evaluation of the small *** with double-balloon enteroscopy, single-balloon enteroscopy and spiral enteroscopy three different platforms are available in clinical ***, double-balloon enteroscopy seems to offer the deepest insertion depth to the small bowel going hand in hand with the disadvantage of a longer procedural duration. Manual spiral enteroscopy seems to be a faster procedure but without reaching the depth of the DBE in currently available data. Finally,single-balloon enteroscopy seems to be the least complicated procedure to perform. Despite substantial improvements in the field of direct enteroscopy,even nowadays deep endoscopic access to the small bowel with all available methods is still a complex procedure, cumbersome and time-consuming and requires high endoscopic skills. This review will give an overview of the currently available techniques and will further discuss the role of the upcoming new technology of the motorized spiral enteroscopy(PowerSpiral).

关键词： Small bowel disease Capsule endoscopy Enteroscopy PowerSpiral enteroscopy Endoscopy