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MC simulation of thermal neutron flux of large samples irradiated by 14 MeV neutrons

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Nuclear Science and Techniques 2010年第1期21卷 11-15页

作者： BAI Yunfei WANG Dezhong MAUERHOFER Eric KETTLER John School of Nuclear Science and Engineering Shanghai Jiao Tong University 200240 Shanghai China Institute of Energy Research IEF-6： Safety Research and Reactor Technology Forschungszentrum Jiilich GmbH 52425 Jiilich Germany

The response of a 14 MeV neutron-based prompt gamma neutron activation analysis (PGNAA) system,*** prompt gamma-rays count rate and the average thermal neutron flux,is studied with a large concrete sample and with a homogeneous large sample,which is made of polyethylene and metal with various concentrations of hydrogen and cadmium using the MCNP-5 (Monte Carlo N-Particle) *** average thermal neutron flux is determined by the analysis of the prompt gamma-rays using the thermal neutron activation of hydrogen in the sample,and the thermal and fast neutron activation of carbon graphite irradiation chamber of the *** results demonstrated that the graphite irradiation chamber of the PGNAA-system fairly operates,and is useful to estimate the average thermal neutron flux of large samples with various compositions irradiated by 14 MeV neutrons.

关键词：中子通量中子辐照大样本 MeV 中子活化分析 PGNAA 瞬发γ射线模拟

Microwave Plasma Sintering of Nanocrystalline Alumina

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Journal of Materials Science & Technology 1998年第2期14卷 173-175页

作者： Peng, Jinhui Hong, Pinjie Dai, Shushan Vollath, D. Szabo, D.V. Kunming Univ Sci & Technol Dept Met Kunming 650093 Peoples R China Yunnan Univ Dept Chem Kunming 650091 Peoples R China forschungszentrum Karlsruhe gmbh Inst Materialforsch III D-76021 Karlsruhe Germany

Sintering of nanocrystalline alumina by microwave plasma has been studied. The relative density, microhardness of the samples with different grain sizes by microwave plasma and sintering techniques have been compared... 详细信息

关键词： Alumina

A review of gas-phase chemical mechanisms commonly used in atmospheric chemistry modelling

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Journal of Environmental Sciences 2023年第1期123卷 522-534页

作者： Yanhui Liu Jiayin Li Yufang Ma Ming Zhou Zhaofeng Tan Limin Zeng Keding Lu Yuanhang Zhang State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Science and EngineeringPeking UniversityBeijing 100871China Institute of Energy and Climate Research IEK-8:TroposphereForschungszentrum Jülich GmbHJülich 52428Germany

The atmospheric chemical mechanism is an essential component of airshed models used for investigating the chemical behaviors and impacts of *** the first tropospheric chemical mechanism was proposed in the 1960s,various mechanisms including Master Chemical Mechanism(MCM),Carbon Bond Mechanism(CBM),Statewide Air Pollution Research Center(SAPRC)and Regional Atmospheric Chemistry Mechanism(RACM)have been developed for different research *** work summarizes the development and applications of these mechanisms,introduces their compositions and lumping methods,and compares the ways the mechanisms treat radicals with box model *** can reproduce urban pollution events with relatively low cost compared to SAPRC and RACM,whereas the chemical behaviors of radicals and the photochemical production of ozone are described in detail in *** photolysis rates of some oxygenated compounds are low in SAPRC07,which may result in underestimation of radical *** an explicit chemical mechanism,MCM describes the chemical processes of primary pollutants and their oxidation products in *** can be used to investigate certain chemical processes;however,due to its large size,it is rarely used in regional model simulations.A box model case study showed that the chemical behavior of OH and HO_(2)radicals and the production of ozone were well described by all *** and SAPRC underestimated the radical levels for different chemical treatments,leading to low ozone production values in both *** and RACM are widely used in box model studies,while CBM and SAPRC are often selected in regional simulations.

关键词： Atmospheric chemistry Gas-phase chemical mechanism Ozone Box model

Soil Organic Matter Composition in Coastal and Continental Date Palm Systems: Insights from Tunisian Oases

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Pedosphere 2019年第4期29卷 444-456页

作者： Rawan K. MLIH Martina I. GOCKE Roland BOL Anne E. BERNS Irabella FUHRMANN Nadhem BRAHIM Institute of Crop Science and Resource Conservation University of Bonn Bonn 53115 (Germany) Agrosphere Institute (IBG-3) Forschungszentrum Julich GmbH Julich 52428 (Germany) Department of Geology University of Tunis El Manar Tunis 2092 (Tunisia)

In Tunisia, the coastal Chenini oasis is characterized by a lush vegetation cover, whereas more inland continental oases(e.g., the Guettaya oasis) have a very scarce vegetation cover. For sustaining date palm production in these areas, organic fertilizers are applied,either spread on the soil surface(in Chenini) or buried under a sand layer(in Guettaya). We examined at a molecular level how these management techniques affect soil organic matter composition in oasis systems. A dominance of fresh plant input for Guettaya was indicated by solid-state 13C nuclear magnetic resonance spectroscopy signals, which was most pronounced in the uppermost soil close to palms. Evidence for more degraded organic matter was found in deeper soil near the palms, as well as in the soil distant from the palms. Amino sugar contents were low in the uppermost Guettaya soil near the palms. The overall microbial amino sugar residue contents were similar in range as those found in other dryland environments. With increasing distance from trees, the amino sugar contents declined in Guettaya, where the palms grow on bare soil, but this was not the case for Chenini, which has multi-layer vegetation cover under palms. In agreement with the results from previous dryland studies, the soil microbial community in both oasis systems was dominated by fungi in topsoil, and a shift toward bacteria-derived residues in subsurface soil. This might be due to higher variability of temperature and moisture in topsoil and/or lower degradability of fungal remains;however, further research is required to confirm this hypothesis.

关键词： amino sugar dryland microbial community soil organic carbon solid-state NMR subsoil amelioration total nitrogen

Nafion/polypyrrole and Nafion/DMSO Organic Coatings for Magnesium Protection

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Journal of Materials Science & Technology 2007年第1期23卷 139-141页

作者： Renguo SONG Xiaohua ZHENG Carsten Blawer Wolfgang Dietzel The MOE Key Laboratory of Mechanical Manufacture and Automation Zhejiang University of Technology Hangzhou 310014 China Center for Magnesium Technology Institute of Materials Research GKSS-Forschungszentrum Geesthacht GmbH Max-Planck Straβe 1 D-21502 Geesthacht Germany

Nafion/polypyrrole and Nafion/Dimethysulfoxid （DMSO） organic coatings were prepared on the surface of pure magnesium by simple immersion and heat treatment. The morphologies and corrosion resistance of the organic coatings were investigated by using optical microscopy and electrochemical corrosion testing, respectively. It is shown that Nafion/polypyrrole organic coatings resulted in the corrosion resistance of magnesium decreasing; while Nafion/DMSO organic coatings can effectively improve the corrosion resistance of magnesium. Also, the corrosion resistance increased with the thickness of the Nafion/DMSO organic coating increased.

关键词： Magnesium Naflon/polypyrrole organic coatings Naflon/DMSO organic coatings Corrosion resistance

Magnesium stress corrosion cracking

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中国有色金属学会会刊：英文版 2007年第A01期17卷 150-155页

作者： N. Winzer A. Atrens W. Dietze G. Song K. U. Kainer Materials Engineering The University of Queensland Brisbane Australia Swiss Federal Laboratories for Materials Science and Technology EMPA Dept 136 lSrberlandstrasse 129 CH-8600 Dubendorf Switzerland GKSS-forschungszentrum Geesthacht gmbh Germany

The significant positive green environment influence of magnesium alloy usage in transport could be compromised by catastrophic fast fracture caused by stress corrosion cracking(SCC). Transgranular stress corrosion cracking(TGSCC) of AZ91 was evaluated using the linearly increasing stress test(LIST) and the constant extension rate test(CERT). The TGSCC threshold stress was 55-75 MPa in distilled water and in 5 g/L NaCl. The TGSCC velocity was 7×10-10-5×10-9 m/s. A delayed hydride-cracking(DHC) model for TGSCC was implemented using a finite element script in MATLAB and the model predictions were compared with experiment. A key outcome is that,during steady state TGSCC propagation,a high dynamic hydrogen concentration is expected to build up behind the crack tip. A number of recommendations are given for preventing SCC of Mg alloys in service. One of the most important recommendations might be that the total stress in service(i.e. the stress from the service loading + the fabrication stress + the residual stress) should be below a threshold level,which,in the absence of other data,could be(conservatively) estimated to be about 50% of the tensile yield strength.

关键词：压力抗腐蚀强度氢化合物合金

HPC-oriented Canonical Workflows for Machine Learning Applications in Climate and Weather Prediction

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Data Intelligence 2022年第2期4卷 271-285页

作者： Amirpasha Mozaffari Michael Langguth Bing Gong Jessica Ahring Adrian Rojas Campos Pascal Nieters Otoniel Jose Campos Escobar Martin Wittenbrink Peter Baumann Martin G.Schultz forschungszentrum Julich gmbh 52425 JulichGermany Osnabruick University 49074O snabrickGermany Jacobs University Bremen 28759 BremenGermany Deutscher Wetterdienst 63067 Offenbach am MainGermany

Machine learning(ML)applications in weather and climate are gaining momentum as big data and the immense increase in High-performance computing(HPC)power are paving the *** FAIR data and reproducible ML practices are significant challenges for Earth system *** though the FAIR principle is well known to many scientists,research communities are slow to adopt *** Workflow Framework for Research(CWFR)provides a platform to ensure the FAIRness and reproducibility of these practices without overwhelming *** conceptual paper envisions a holistic CWFR approach towards ML applications in weather and climate,focusing on HPC and big ***,we discuss Fair Digital Object(FDO)and Research Object(RO)in the DeepRain project to achieve granular *** is a project that aims to improve precipitation forecast in Germany by using *** concept envisages the raster datacube to provide data harmonization and fast and scalable data *** suggest the Juypter notebook as a single reproducible *** addition,we envision JuypterHub as a scalable and distributed central platform that connects all these elements and the HPC resources to the researchers via an easy-to-use graphical interface.

关键词： FAIR Reproducibility Machine learning Earth system sciences Workflow

Fabrication of Anodic Aluminum Oxide Templates with Small Interpore Distances

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Chinese Physics Letters 2010年第6期27卷 148-151页

作者： WANG Na ZHANG Wen-Di XU Ji-Peng MA Bin ZHANG Zong-Zhi JIN Qing-Yuan E. Bunte J. Hupkes H. P. Bochem Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) Laboratory of Advanced Materials and Department of Optical Science and Engineering Fudan University Shanghai 200433 IEFS-Photovoltaik Forschungszentrum Jfilich GmbH D-52425 Julich Germany Institut fur Bio-und Nanosysteme (IBN-PT) julich GmbH D52425 Julich Germany

The influence of the electropolishing and anodization voltage on surface morphology has been carefully studied for fabrication of ordered anodic aluminum oxide （AAO） templates. In accordance with that in the anodization experiment, the size of small patterns on the foil surface formed from the electropolishing treatment increases with voltage. Using a combined method of small-voltage eleetropolishing and anodization, we have fabricated well ordered templates with much smaller interpore distances compared with that under normal-voltage fabrication conditions. The Ni nanowire arrays with two small diameters are eleetrodeposited through the above templates, exhibiting different magnetic properties. This also helps us to clarify the inner structure of this kind of templates.

关键词： MICROFABRICATION ALUMINUM oxide POROUS materials ELECTROLYTIC polishing SURFACES (Technology) CHEMICAL templates NANOWIRES MAGNETIC properties

Evaluation of the Electrical Contact Area at the SOFC Cathode

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Journal of Energy and Power Engineering 2011年第5期5卷 474-479页

作者： V.A.C. Haanappel I.C. Vinke L.G.J. de Haart D. Stolten Institute of Energy Research Forschungszentrum Jiilich GmbH Jalich 52425 Germany

In the frame of the ZeuS-Ill project, a model study was started on evaluation the area-specific resistances （ASRs） of various layers being used in SOFC stacks. It is well known that stack performance not only depends on cell resistance but also on the electrical conductivity of the various applied contact and protective layers. Various layers have been tested under simulated SOFC conditions, and results have shown that the lowest ASR value, about 3 mΩ.cm2, was obtained for an LSM （2） contact layer. A significantly higher resistance was found for the combined contact and protective layer LCC10-Mn3O4, being around 37 mΩ.cm2 Related to the various tests, the total ASR of an F-design stack, developed by forschungszentrum Jiilich, under ideal conditions can be estimated. In this case the ASR value was calculated as the sum of that of the LCC10-Mn3O4 layer and the formed oxide scale due to oxidation of Crofer22APU. Contacting resistance at the anode side was considered negligible. When differences in the ASR values occurred when compared with that from current-voltage measurements performed with real SOFC stacks, this can be explained by the limited contact area between interconnect and cathode. These results can be used to model the influence of various applied layers and different geometric contact areas on the overall ASR as determined from performance measurements with SOFC stacks.

关键词： Area-specific resistance (ASR) SOFCs cathode electrical conductivity contact layer.