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Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

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材料热处理学报 2004年第5期25卷 607-611页

作者： Karl killer stefan Wiebach ALD Vacuum Technologies AG Hanau - GermanyALD Vacuum Technologies AG Hanau - Germany

IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

关键词：真空热处理真空渗碳高压气体流淬火炉子

Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings

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Journal of Materials Science & Technology 2022年第5期100卷 91-100页

作者： Nikolaus Jager Michael Meindlhumer Michal Zitek stefan Spor Hynek Hruby Farwah Nahif Jaakko Julin Martin Rosenthal Jozef Keckes Christian Mitterer Rostislav Daniel Christian Doppler Laboratory for Advanced Synthesis of Novel Multifunctional Coatings at the Department of Materials Science Montanuniversität LeobenAustria voestalpine eifeler Vacotec GmbH DüsseldorfGermany Institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-RossendorfDresdenGermany Department of Physics University of JyvaskylaFinland European Synchrotron Radiation Facility GrenobleFrance Erich Schmid Institute for Materials Science Austrian Academy of SciencesAustria Department of Materials Science Montanuniversität LeobenAustria

The resistance of wear protective coatings against oxidation is crucial for their use at high ***,three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%,2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry,thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their ***,a partially oxidized AlCrSiN coating with 5 at.%Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition,morphology,phases and residual stress evolution of the oxide scale and the non-oxidized coating *** results reveal enhanced oxidation properties of the AlCr(Si)N coatings with increasing Si-content,as demonstrated by a retarded onset of oxidation to higher temperatures from 1100℃ for AlCrN to 1260℃ for the Si-containing coatings and a simultaneous deceleration of the oxidation *** annealing of the AlCrSiN sample with5 at.%Si at an extraordinary high temperature of 1400℃ for 60 min in ambient air,three zones developed throughout the coating strongly differing in their composition and structure:(i)a dense oxide layer comprising an Al-rich and a Cr-rich zone formed at the very top,followed by(ii)a fine-grained transition zone with incomplete oxidation and(iii)a non-oxidized zone with a porous *** varying elemental composition of these zones is furthermore accompanied by micro-structural variations and a complex residual stress development revealed by cross-sectional X-ray *** results provide a deeper understanding of the oxidation behavior of AlCr(Si)N coatings depending on their Si-content and the associated elemental,microstructural and residual stress evolution during high-temperature oxidation.

关键词： AlCrSiN Nanocomposite Cathodic arc Oxidation behaviour Cross-sectional X-ray nanodiffraction

Database and primer selections affect nematode community composition under different vegetations of Changbai Mountain

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Soil Ecology Letters 2023年第1期5卷 142-150页

作者： Yixin Sun Xiaofang Du Yingbin Li Xu Han Shuai Fang stefan Geisen Qi Li CAS Key Laboratory of Forest Ecology Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China Laboratory of Nematology Wageningen UniversityWageningenThe Netherlands

High-throughput sequencing technology is increasingly used in the study of nematode ***,the annotation difference of commonly used primers and reference databases on nematode community is still *** compared two pairs of primers(3NDf/C_1132rmod,NF1F/18Sr2bR)and three databases(NT_V20200604,SILVA138/18s Eukaryota and PR2_v4.5 databases)on the determination of nematode community from four different vegetation types in Changbai Mountain,including mixed broadleaf-conifer forest,dark coniferous forest,betula ermanii Cham and alpine *** results showed that the selection of different primers and databases influenced the annotation of nematode taxa,but the diversity of nematode community showed consistent pattern among different vegetation *** findings emphasize that it is necessary to select appropriate primer and database according to the target taxonomic *** difference in primers will affect the result of nematode taxa at different classification levels,so sequencing analysis cannot be used for comparison with studies using different *** terms of annotation effect in this study,3NDf/C_1132rmod primers with NT_v20200604 database could provide more information than other combinations at the genus or species levels.

关键词： Soil nematodes Primer Database High-throughput sequencing Community composition

Photovoltaic yield prediction using an irradiance forecast model based on multiple neural networks

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Journal of Modern Power Systems and Clean Energy 2018年第2期6卷 255-267页

作者： Saad Parvaiz DURRANI stefan BALLUFF Lukas WURZER stefan KRAUTER Paderborn University Bosch Thermotechnik GmbH

In order to develop predictive control algorithms for efficient energy management and monitoring for residential grid connected photovoltaic systems, accurate and reliable photovoltaic(PV) power forecasts are required.A PV yield prediction system is presented based on an irradiance forecast model and a PV model. The PV power forecast is obtained from the irradiance forecast using the PV model. The proposed irradiance forecast model is based on multiple feed-forward neural networks. The global horizontal irradiance forecast has a mean absolute percentage error of 3.4% on a sunny day and 23% on a cloudy day for Stuttgart. PV power forecasts based on the neural network irradiance forecast have performed much better than the PV power persistence forecast model.

关键词： Grid connected photovoltaic(GCPV) Photovoltaic(PV) PV power prediction Irradiance forecast Neural network(NN)

Neutron diffraction studies on ‘‘simple'' iron oxides under pressure: Fe_3O_4, a-Fe_2O_3, and FeO

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Chinese Science Bulletin 2014年第36期59卷 5241-5250页

作者： stefan Klotz IMPMC CNRS UMR 7590 Universite' Pierre & Marie Curie75252 Paris France

Fe3O4(magnetite), a-Fe2O3(hematite), and Fe O(wu¨ stite) are the three major iron oxides and some of the most fundamental solids in nature. Interest in these systems is due to their abundance as minerals in the Earth and other telluric planets as well as their interesting electronic and magnetic properties which have been studied for decades. In this article, we review high-pressure studies on these three systems using neutron powder diffraction in the0–14 GPa range with a particular focus on the behavior of magnetism under pressure. Unpublished data on the pressure dependence of the Ne′el temperature in Fe O are presented. This review will give at the same time an introduction into technical aspects and illustrate the potential of high-pressure neutron scattering in the future.

关键词：四氧化三铁 α-氧化铁中子衍射 α-Fe2O3 磁压力 FeO 中子散射磁铁矿

Galerkin Spectral Method Applied to the Chemical Master Equation

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Communications in Computational Physics 2009年第5期5卷 871-896页

作者： stefan Engblom Department of Information Technology Uppsala UniversityP.O.Box 337SE-75105 UppsalaSweden

Stochastic well-stirred chemically reacting systems can be accurately modeled by a continuous-time *** corresponding master equation evolves the system’s probability density function in time but can only rarely be explicitly *** investigate a numerical solution strategy in the form of a spectral method with an inherent natural adaptivity and a very favorable choice of basis *** results related to convergence have been developed previously and are briefly summarized while implementation issues,including how to adapt the basis functions to follow the solution they represent,are covered in more detail *** method is first applied to a model problem where the convergence can easily be *** we take on two more realistic systems from molecular biology where stochastic descriptions are often necessary to explain experimental *** conclusion is that,for sufficient accuracy demands and not too high dimensionality,the method indeed provides an alternative to other methods.

关键词： Master equation spectral-Galerkin method high dimensional problem moving basis chemical reactions

Current treatment options and response rates in children with chronic hepatitis C

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World Journal of Gastroenterology 2012年第2期18卷 99-104页

作者： stefan Wirth Helios Medical Centre Wuppertal Department of PediatricsWitten-Herdecke UniversityD-42283 WuppertalGermany

Vertical transmission has become the most common mode of transmission of hepatitis C virus (HCV) in *** rate of perinatal transmission from an HCVinfected mother to her child ranges from 2% to 5% and the prevalence of HCV in children in developed countries ranges between 0.1% and 0.4%.Spontaneous viral clearance seems to be dependent on the genotype and has been reported between 2.4%-25%.For chronically infected patients,treatment with recombinant polyethylene glycol (PEG)-interferon α-2b and daily ribavirin has now been approved as standard treatment for children 2-17 years of *** five large prospective studies,a total of 318 children and adolescents aged 3-17 years were treated either with subcutaneous PEG-interferon α-2b at a dose of 1-1.5 μg/kg or 60 μg/m2 once a week in combination with oral ribavirin (15 mg/kg per day) or PEG-interferon α-2a with *** with genotype 1 and 4 received the medication for 48 wk and individuals with genotype 2 and 3 mainly for 24 *** sustained viral response (SVR) was achieved in 193/318 (60.7%) of treated *** for genotype;120/234 (51%) with genotype 1,68/73 (93%) with genotype 2/3,and 6/11 (55%) with genotype 4 showed *** rate was between 7.7% and 17%.Overall,treatment was well tolerated;how-ever,notable side effects were present in approximately 20%.According to recent experiences in the treatment of chronic hepatitis C in children and adolescents,a combination of PEG-interferon α with ribavirin has been found to be well tolerated and highly efficacious,particularly in individuals with genotype 2/***,this treatment can be recommended as standard of care until more effective treatment options will become available for genotype 1 patients.

关键词：丙型肝炎病毒治疗方案慢性感染儿童利巴韦林传播模式基因型干扰素

A customizable,low-power,wireless,embedded sensing platform for resistive nanoscale sensors

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Microsystems & Nanoengineering 2022年第1期8卷 111-121页

作者： stefan Nedelcu Kishan Thodkar Christofer Hierold Micro-and Nanosystems Department of Mechanical and Process EngineeringETH ZurichTannenstrasse 38092 ZurichSwitzerland

Customizable,portable,battery-operated,wireless platforms for interfacing high-sensitivity nanoscale sensors are a means to improve spatiotemporal measurement coverage of physical *** a platform can enable the expansion of IoT for environmental and lifestyle *** we report a platform capable of acquiring currents ranging from 1.5 nA to 7.2μA full-scale with 20-bit resolution and variable sampling rates of up to 3.125 *** addition,it features a bipolar voltage programmable in the range of-10 V to+5 V with a 3.65 mV resolution.A Finite State Machine steers the system by executing a set of embedded *** FSM allows for dynamic,customized adjustments of the nanosensor bias,including elevated bias schemes for self-heating,measurement range,bandwidth,sampling rate,and measurement time ***,it enables data logging on external memory(SD card)and data transmission over a Bluetooth low energy *** average power consumption of the platform is 64.5 mW for a measurement protocol of three samples per second,including a BLE advertisement of a 0 dBm transmission power.A state-of-the-art(SoA)application of the platform performance using a CNT nanosensor,exposed to NO_(2) gas concentrations from 200 ppb down to 1 ppb,has been *** sensor signals are measured for NO_(2) concentrations of 1 ppb,the 3σlimit of detection(LOD)of 23 ppb is determined(1σ:7 ppb)in slope detection mode,including the sensor signal variations in repeated *** platform’s wide current range and high versatility make it suitable for signal acquisition from resistive nanosensors such as silicon nanowires,carbon nanotubes,graphene,and other 2D *** with its overall low power consumption,the proposed platform is highly suitable for various sensing applications within the context of IoT.

关键词： power IoT enable

MP-PIC simulation of circulating fluidized beds using an EMMS based drag model for Geldart B particles

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Particuology 2021年第6期19卷 76-90页

作者： Timo Dymala Tom Wytrwat stefan Heinrich Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestr.1521073 HamburgGermany

In this study the multiphase particle-in-cell(MP-PIC)method is used for the simulation of two pilot-scale circulating fluidized beds(CFBs)with quartz sand belonging to Geldart’s group B as bed *** simulations were performed using a homogeneous drag model as well as a structure dependent drag model based on the energy minimization multi-scale method(EMMS).The results are compared with experimental data from literature as well as *** simulations with the EMMS based drag model show a good agreement of the time-averaged axial solids concentration,circulation rate and riser pressure ***,a lower grid sensitivity is observed compared to the homogeneous drag *** contrast to the conventional drag model a dense bottom zone is predicted by the EMMS based drag *** overprediction of the solid concentration in the dense bottom zone is presumably due to an overprediction of the cluster diameter that is calculated using an empirical cluster diameter *** shows the necessity for a new meso-scale cluster correlation for the simulation of Geldart B ***,the results of the time-averaged radial solids concentration differ from the expectations of a core-annulus flow indicating that a mesh refinement at the walls is ***,the importance of using a realistic particle size distribution is identified.

关键词： 3D-CFD simulation Circulating fluidized bed(CFB) Multiphase particle-in-cell method(MP-PIC) Energy minimizing multi-scale theory(EMMS) Validation study