检索结果-南通市图书馆

＂Global Sustainable Information Society＂ Vision for the Future

在线全文

学校读者我要写书评

暂无评论

学术界 2014年第1期 254-258页

作者： wolfgang Hofkirchner Unified Theory of Information (UTI) Research Group

Social systems are another variety of evolutionary *** synergetic effects are the so-called *** systems show a dialectic of individualisation and *** the individual element takes center stage,the commons are ***,in the age of global challenges,the enclosure of the commons is not sustainable any more.A supra-system needs to be built up that takes care of a unity-through-diversity relation between all actors,be they individual or ***'s the rationale of the vision of a Global Sustainable Information Society.

关键词：全球可持续发展信息社会展望进化系统社会制度协同效应多样性

Palaeogeography of a shallow carbonate platform:The case of the Middle to Late Oxfordian in the Swiss Jura Mountains

在线全文

学校读者我要写书评

暂无评论

Journal of Palaeogeography 2015年第3期4卷 251-268页

作者： André Strasser Bernard Pittet wolfgang Hug Department of Geosciences University of Fribourg Université Lyon 1 UMR CNRS LGLTPE 5276Campus DouaBatiment Géode69622 VilleurbanneFrance Paléontologie A16 Section d'archéologie et paléontologieOffice de la cultureH?tel des Halles2900 PorrentruySwitzerland

The Oxfordian （Late Jurassic） carbonate-dominated ptatform outcropping in the Swiss Jura Mountains offers a good biostratigraphic, sequence-stratigraphic, and cyclostratigraphic framework to reconstruct changes in facies distribution at a time-resolution of 100 ka. It thus allows interpreting the dynamic evolution of this platform in much more detail than conventional palaeogeographic maps permit. As an example, a Middle to Late Oxfordian time slice is presented, spanning an interval of about 1.6 Ma. The study is based on 12 sections logged at cm-scale. The interpreted depositional environments include marginal-marine emerged ;ands, fresh-water lakes, tidal fiats, shallow lagoons, ooid shoals, and coral reefs. Although limestones dominate, marly intervals and dolomites occur sporadically. Major facies shifts are related to m-scale sea-level changes linked to the orbital short eccentricity cycle （100 ka）. The 20-ka precession cycle caused minor facies changes but cannot always be resolved. Synsedimentary tectonics induced additional accommodation changes by creating shallow basins where days accumulated or highs on which shoals or islands formed. Autocyclic processes such as lateral migration of ooid and bioclastic shoals added to the sedimentary record. CEimate changes intervened to control terrestrial run-off and, consequently, siliciclastic and nutrient input. Coral reefs reacted to such input by becoming dominated by microbialites and eventually by being smothered. Concomitant occurrence of siliciclastics anddolomite in certain intervals further suggests that, at times, it was relatively arid in the study area but there was rainfall in more northern latitudes, eroding the Hercynian substrate. These examples from the Swiss Jura demonstrate the highly dynamic and （geologically speaking） rapid evolution of sedimentary systems, in which tectonically controlled basin morphology, orbitally induced climate and sea-level changes, currents, and the ecology of the carbon

关键词： Swiss Jura Oxfordian carbonate platform facies evotution sequence stratigraphy cyclostratigraphy

Formation of internal cracks in steel billets during soft reduction

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2008年第2期15卷 114-119页

作者： Wenjun Wang Linxin Ning Raimund Biilte wolfgang Bleek Institute of Ferrous Metallurgy RWTH Aachen University Aachen 52072 Germany Shougang Group Research Institute Beijing 100041 China

To investigate the formation of internal cracks in steel billets during soft reduction, fully coupled thermo-mechanical finite element models were developed using the commercial software ABAQUS, also casting and soft reduction tests were carried out in a laboratory strand casting machine. With the finite element models, the temperature distribution, the stress and strain states in the billet were calculated. The relation between internal cracks and equivalent plastic strain, as well as maximal principal stress was analyzed. The results indicate that tensile stresses can develop in the mushy zone during soft reduction and the equivalent strain nearby the zero ductility temperature （ZDT） increases with decreasing solid fraction. Internal cracks can be initiated when the accumulated strain exceeds the critical strain or the applied tensile stress exceeds the critical fracture stress during solidification.

关键词： steel soft reduction finite element model internal cracks

Synthesis and Characterization of(Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films Formed by a Diol-based Sol-gel Process

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第6期28卷 500-505页

作者： Sebastian Wiegand Stefan Flege Olaf Baake wolfgang Ensinger Technische Universitt Darmstadt Department of Materials and GeosciencesMaterials Analysis GroupPetersenstrasse 2364287 DarmstadtGermany

Lead-free （***0.5）Nb03 （NKN） thin films were fabricated by spin coating on Pt/Ti/SiO2/Si substrates by a diol-based sol-gel process. Na-acetate, K-acetate, Nb-pentaethoxide and 1,3 propanediol were used to prepare the NKN precursor solution. Thermal analysis showed two characteristic temperatures of 360 and 600℃. Based on these temperatures, a heat treatment program with pyrolysis at 360℃ and calcination at 600℃ after every layer was used. To avoid inhomogeneities and secondary phases, an excess of sodium and potassium was necessary. To evaluate the proper excess amount of sodium and potassium secondary ion mass spectrometry （SIMS） lateral element maps and X-ray diffraction （XRD） patterns were recorded. An excess amount of 20% led to homogeneous distribution of the elements and to single phase perovskite NKN films with random crystal orientation. Scanning electron microscopy （SEMI images showed a pore free surface with 100 nm grains. The leakage current measurements showed a current of lx10-3 A/cm2 at 150 kV/cm.

关键词： Sol-gel process (Nao.sK0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Influence of PVD-duplex-treated, Bionic Surface Structures on the Wetting Behavior for Sheet-Bulk Metal Forming Tools

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2017年第3期14卷 520-531页

作者： wolfgang Tiilmann Dominic Stangier Nelson Filipe Lopes Dias Institute of Materials Engineering TU Dortmund 44227 Dortmund Germany Leonhard-Euler-Strafle 2

Bionic surface structures, inspired by the flora, were developed for Sheet-Bulk Metal Forming （SBMF） in order to locally control the friction condition by adjusting the wetting behavior. Five bionic structures were micromilled on ASP 2023 in annealed as well as hardened and tempered conditions. Subsequently, the structured surfaces were plasma-nitrided and coated with a CrA1N thin film. The influence of the treatment method on the structural geometry was investigated with the aid of a scanning electron microscope and 3D-profilometer. The wetting behaviors of water and deep drawing oil （Berufluid ST6007） on bionic surfaces were evaluated using contact angle measurements. The resulting micro-milled structures exhibit an almost identical shape as their bionic models. However, the roughness of the structured surfaces is influenced by the microstructure. The combination of plasma-nitriding and Physical Vapor Deposition （PVD） leads to an increase in roughness. All bionic struc- tures possess higher contact angles than that of the unstructured surfaces when wetted by water. This can be explained by the fact that the structural elevations block the spreading. When the bionic surfaces are wetted by deep drawing oil, the lubricant spreads in the structural cavities, leading to smaller contact angles. Furthermore, the anisotropy of the structure has an influence on the wetting behavior.

关键词： bionic structures sheet-bulk metal forming CrA1N PVD-duplex treatment wetting behavior

Semi-hot Stamping as an Improved Process of Hot Stamping

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

Journal of Materials Science & Technology 2011年第4期27卷 369-376页

作者： Malek Naderi Mostafa Ketabchi Mahmoud Abbasi wolfgang Bleck Department of Mining and Metallurgy Amirkabir University of Technology Department of Ferrous Metallurgy RWTH-Aachen University

Reducing the forming load, deletion of springback, increasing the formability of sheets as well as producing high strength parts are the main reasons to apply hot stamping process. Hot stamping process and 22MnB5 steels are the state of the art process and grades, respectively; however novel processes and steel grades are under considerations. In the current research, behavior of the steel grade MSW1200 blanks under semi and fully hot stamping processes was characterized. During semi-hot stamping process, the blank was firstly heated to a temperature of about 650℃ and then formed and quenched in the die assembly, simultaneously. Microstructure and mechanical properties of semi and fully hot stamped blanks were studied and the results were compared with those of normally water/air quenched blanks. The hot stamped blanks attained the strength values as high as water quenched blanks. The highest ductility and consequently, the best formability were achieved for the blank which had been semi-hot stamped. It was concluded that for the mentioned steel, semi-hot stamping process could be considered as an improved thermo-mechanical process which not only guaranteed a high formability, but also led to ultra high strength values.

关键词： Semi-hot stamping Hot stamping MSW1200 steel Mechanical properties

Effect of Different Calcination Temperatures and Post Annealing on the Properties of Acetic Acid Based Sol-Gel (Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2013年第2期29卷 142-148页

作者： Sebastian Wiegand Stefan Flege Olaf Baake wolfgang Ensinger Materials Analysis Group Department of Materials and Geosciences Technische Universitt Darmstadt Petersenstrasse 23 64287 Darmstadt Germany

（Na0.5K0.5）NbO3 （NKN） lead free thin films were synthesized by means of an acetic acid based sol-gel process on Pt/Ti/SiO2/Si substrates. Na-acetate, K-acetate and Nb-pentaethoxide were used as metal precursors and acetic acid as the solvent. The effect of different calcination temperatures on the properties of the NKN films was investigated by X-ray diffraction, scanning electron microscopy, leakage current and hysteresis measurements. Low calcination temperatures led to low currents at high electric fields whereas high calcination temperatures led to low currents at low electric fields. Based on these findings calcination at low temperature was combined with a post annealing treatment. Low leakage currents of 4×10^-4 A/cm2 at 150 kV/cm and 2Pr and 2Ec values of 28 μC/cm2 and 150 kV/cm, respectively, could be obtained. All films were single phase NKN with random crystal orientations and no crack or pore formation was visible on the surface.

关键词： Sol-gel process (Na0.5K0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Long-term monitoring data reveal effects of age,population density,and environmental aspects on hatching success of Common Cranes(Grus grus)

在线全文

学校读者我要写书评

暂无评论

Avian Research 2022年第3期13卷 347-355页

作者： Isabel Barwisch wolfgang Mewes Angela schmitz Ornes AG Vogelwarte Zoological Institute and MuseumUniversity of GreifswaldSoldmannstr.23GreifswaldGermany Grüner Weg 3 19395Plau Am SeeOT KarowGermany

Facing climate and land use change,a species’ability to successfully adapt to changing environments is crucial for its *** drainage and intensification of agriculture and forestry set wetlands and associated species at risk of population *** population of Common Cranes(Grus grus)has experienced considerable fluctuations over the last *** increasing population numbers,hatching success seemed to have decreased over the last *** aim of this study was to identify factors influencing hatching success and nest survival of Common Cranes based on analyses of long-term individual-based monitoring data from northeastern Germany and evaluate the species ability to adapt to changing *** success decreased over the course of the study period from 0.75 to ***,nest survival and hatching success did not vary across different nesting habitats,whereas factors such as female age,timing of nest initiation and breeding pair density were found to have significant effects on hatching *** females showed higher hatching success,even though the proportion of unhatched eggs was highest in females aged 20 years or *** nest initiation had a positive effect on hatching *** levels are more favorable early in the nesting season,whereas increasing evaporation with time causes water levels to decrease,granting easier access for *** of female age,hatching success decreased with increasing numbers of breeding pairs within a 2-km radius around a nesting *** population densities intensify competition for resources and promote intraspecific interactions,affecting reproductive outcome *** study gives first insights into mechanisms behind population regulation in Common Cranes,highlighting the importance of population dynamics and individual *** suggest to further investigate density dependent effects including landscape and habitat features as well as reproduct

关键词： Adaptation Age Cranes Grus grus Habitat Nest survival Population density Reproduction

A new hybrid piezoelectric ultrasonic motor with two stators

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University of Technology 2005年第3期12卷 324-328页

作者：易幼平 wolfgang Seemann Rainer Gausmann 钟掘 College of Mechanical and Electrical Engineering Central South University Changsha 410083China Institut für Technische Mechanik Universitt KarlsruheKarlsruhe 76128Germany AG Maschinendynamik Universitt Kaiserslautern Kaiserslautern 67653 Germany

A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.

关键词： piezoelectric ultrasonic motor lead zirconate titanate resonance frequency vibration