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Sparse Approximations of the Schur Complement for Parallel Algebraic Hybrid Solvers in 3D

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Numerical Mathematics(Theory,Methods and Applications) 2010年第3期3卷 276-294页

作者： l.Giraud A.Haidar y.Saad Joint INRIA-CERFACS lab-42 AV.Coriolis 31057ToulouseFrance Department of Computer Science University of TennesseeKnoxvilleTN37996USA. Department of Computer Science and Engineering University of MinnesotaMinneapolisMN55455USA

In this paper we study the computational performance of variants of an algebraic additive Schwarz preconditioner for the Schur complement for the solution of large sparse linear *** earlier works,the local Schur complements were computed exactly using a sparse direct *** robustness of the preconditioner comes at the price of this memory and time intensive computation that is the main bottleneck of the approach for tackling huge *** this work we investigate the use of sparse approximation of the dense local Schur *** approximations are computed using a partial incomplete lu *** a numerical calculation is the core of the multi-level incomplete factorization such as the one implemented in pARMS. The numerical and computing performance of the new numerical scheme is illustrated on a set of large 3D convection-diffusion problems;preliminary experiments on linear systems arising from structural mechanics are also reported.

关键词： Hybrid direct/iterative solver domain decomposition incomplete/partial factorization Schur approximation scalable preconditioner convection-diffusion large 3D problems parallelscientific computing High Performance Computing.

Assessment of semi-empirical mass transfer correlations for pervaporation treatment of wastewater contaminated with chlorinated hydrocarbons

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2006年第11期7卷 1911-1916页

作者： lIu Sean x. Department of Food Science Rutgers University New Brunswick NJ 08901-8520 USA

Assessment of mass transfer characteristics of pervaporation （PV） treatment of wastewater contaminated with chlorinated hydrocarbons is of great importance for water treatment plant operators conducting initial evaluation, process optimization, and process economics. While a membrane plays a central role in pervaporation processes and separation efficiency, the mass transfer in the liquid layer next to the membrane surface is of equal, if not greater importance. It is one of the few process parameters that can be adjusted in situ to manipulate the outcome of a pervaporation process. In this study, a bench scale pervaporation experiment of removing a common chlorinated hydrocarbon from water was carried out and the results of it were compared to the ones based on well-known semi-empirical correlations. The mass transfer coefficients from the experiments, ranging from 0.8× 10^-5-2.5× 10^-5 m/s under the operating conditions, are higher than those predicted by the correlation. The corresponding separation factors under varying flow velocities are determined to be between 310-950.

关键词： Chlorinated hydrocarbon Mass transfer Pervaporation Wastewater treatment

luminescence investigation of Dy2O2S and Dy2O2SO4 obtained by thermal decomposition of sulfate hydrate

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Journal of Rare Earths 2016年第8期34卷 814-819页

作者： R.V.Rodngues l.Marciniak l.u.Khan J.R.Matos H.F.Brito W.Strek Institute of Chemistry University of Sao Paulo Butanta 748 26077 Sao Paulo Brasil Institute of low Temperature and Structure Research University of Wroctaw Oko1na 250-422 Wroclaw Poland

The yellow emitting dysprosium oxysulfide （Dy2O2S） and dysprosium oxysulfate （Dy202SO4） compounds were prepared from the thermal decomposition of hydrated dysprosium sulphate. The materials were characterized by using thermogravimetry （TG/DTG）, x-ray powder diffraction （xRD）, Fourier transform infrared （FTIR） and Raman spectroscopies. The thermal stability temperatures at around 1151 and 1313 K were determined for the Dy202S and Dy202SO4 materials, respectively. The photolumines- cence properties of the dysprosium oxysulfide were investigated, showing narrow emission bands assigned to the 4F9/2----＊6HJ intracon- figurational transitions of the Dy3＋ ion. The yellow emission color of this phosphor suggests that the Dy202S is a promising material for applications in lEDs.

关键词： Dy202S/Dy202SO4 sulfate thermal decomposition luminescence rare earths

Near Earth Vortices Driving of Field Aligned Currents Based on Magnetosphere Multiscale and Swarm Observations

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空间科学学报 2019年第1期39卷 9-17页

作者： ZHANG C SHEN C yANG y y DuNlOP M W TI S RuSSEll C T lüHR H BuRCH J l lINDQVIST P A TORBERT R B FRIIS-CHRISTENSEN E State Key laboratory of Space Weather National Space Science Center College of Earth Science University of Chinese Academy of Sciences College of Science Harbin Institute of Technology Institute of China Seismological Bureau Crustal Stress Space Science Institute School of Astronautics Beihang University Rutherford Appleton laboratory university of California German Research Center For Geosciences German Research Center for Geosciences Southwest Research Institute Royal Institute of Technology university of New Hampshire Danish National Space Center

A long-standing mystery in the study of Field-Aligned Currents(FACs) has been that: how the currents are generated and why they appear to be much stronger at high altitudes than in the ionosphere. Here we present two events of magnetotail FACs observed by the Magnetospheric Multiscale Spacecraft(MMS) on 1 st July and 14 th July 2016, to show how the Substorm Current Wedges(SCW) were formed. The results show that particles were transferred heading towards the Earth during the expansion phase of *** azimuthal flow formed clockwise(counter-clockwise) vortex-like motion, and then generated downward(upward) FACs on the tailward/poleward side of the distorted field with opposite vorticity on their Earthward/equatorward side. We also analyzed the Region 1 FACs observed by the Earth Explorer Swarm spacecraft on 1 st July 2016 and found that they were associated with FACs observed by MMS, although differing by a factor of 10. This difference suggests that either there was the closure of the currents at altitudes above 500 km or the currents were not strictly parallel to B and closed at longitudes away from where they were generated.

关键词： Substorm current wedge Magnetosphere Field-aligned currents Flow vorticity Multiple spacecraft measurements

General investigation for longitudinal wave propagation under magnetic field effect via nonlocal elasticity

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Applied Mathematics and Mechanics(English Edition) 2015年第10期36卷 1305-1318页

作者： u.GVEN Department of Mechanical Engineering Yildiz Technical University

In this paper, the propagation of longitudinal stress waves under a longitu- dinal magnetic field is addressed using a unified nonlocal elasticity model with two scale coefficients. The analysis of wave motion is mainly based on the love rod model. The effect of shear is also taken into account in the framework of Bishop＇s correction. This analysis shows that the classical theory is not sufficient for this subject. However, this unified nonlocal elasticity model solely used in the present study reflects in a manner fairly realistic for the effect of the longitudinal magnetic field on the longitudinal wave propagation.

关键词： Rayleigh-Bishop rod nonlocal elasticity magnetic field wave propagation

Physico-chemical characterization of a farmland affected by wastewater in relation to heavy metals

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2008年第3期9卷 366-372页

作者： Emmanuel u. ONWEREMADu Department of Soil Science and Technology Federal university of Technology PMB 1526 Owerri Nigeria

This study investigated selected properties of soils affected by wastewater and its relationship with some heavy metals. A free survey technique involving target sampling was used in siting soil profile pits. Soil samples were collected based on horizon differentiation and analyzed using routine and special analytical techniques. Soil data were subjected to correlation analysis using SAS program. Results show that all heavy metals studied had values above critical limits in the polluted soils using known standards and that these biotoxic metals decreased with soil depths. Highly significant (P=0.01 and 0.05) relationships were established between investigated heavy metals and some soil properties, especially soil pH and organic matter. Further studies involving more edaphic properties, biotoxic metals and their bioaccessibility in crops growing on wastewater soils will surely enhance knowledge and management of these highly anthropogenically influenced soils of the study site.

关键词： Bioavailability Characterization Heavy metals Soil pollution Wastewater

Grenvillian orogeny in the Southern Cathaysia Block:Constraints from u-Pb ages and lu-Hf isotopes in zircon from metamorphic basement

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Chinese Science Bulletin 2008年第19期53卷 3037-3050页

作者： WANG liJuan yu JinHai S.y. O'REIlly W.l. GRIFFIN SuN Tao WEI Zhenyang JIANG Shaoyong SHu liangShu State Key laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China GEMOC National Key Centre Department of Earth and Planetary Science Macquarie University Sydney NSW 2109 Australia

Metamorphic basement rocks in the Cathaysia Block are composed mainly of meta-sediments with different ages. New zircon u-Pb geochronological results from the meta-sedimentary rocks exposed in the Zengcheng and Hezi areas, southern Cathaysia Block, show that they consist dominantly of early Neoproterozoic (1.0―0.9 Ga) materials with minor Paleo- to Mesoproterozoic and late Neoproterozoic (0.8―0.6 Ga) components, suggesting that the detritus mostly come from a Grenvillian orogen. The youngest detrital zircon ages place a constraint on the deposition time of these sediments in late Neoproterozoic. Zircon Hf isotopic compositions indicate that the Grenvillian zircons were derived from the reworking of Mesoproterozoic arc magmatic rocks and Paleoproterozoic continental crust, implying an arc-continent collisional setting. Single-peak age spectra and the presence of abundant euhedral Grenvillian zircons suggest that the sedimentary provenance is not far away from the sample location. Thus, the Grenvillian orogen probably preexisted along the southern margin of the Cathaysia Block, or very close to the south. Similarity in the ages of Grenvillian orogeny and the influence of the assembly of Gondwana in South China with India and East Antarctic are discussed, with suggestion that South China was more likely linked with the India-East Antarctica continents in Early Neoproterozoic rather than between western laurentia and eastern Australia.

关键词：华夏古大陆格伦维尔期锆石同位素新元古代

Semi-solid near-net shape rheocasting of heat treatable wrought aluminum alloys

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1719-1724页

作者： u.A.C uRlE Materials Science and Manufacturing Council for Scientific and Industrial Research

Flexibility of the CSIR-RCS, induction stirring with simultaneous air cooling process, in combination with high pressure die casting is successfully demonstrated by semi-solid rheocasting of plates performed on commercial 2024, 6082 and 7075 wrought aluminum alloys. Tensile properties were measured for the above mentioned rheocast wrought aluminum alloys in the T6 condition. The results showed that tensile properties were close to or even in some cases exceeded the minimum specifications. The yield strength and elongation of rheocast 2024-T6 exceeded the minimum requirements of the wrought alloy in the T6 condition but the ultimate tensile strength achieved only 90% of the specification because the Mg content of the starting alloy was below the commercial alloy specification. The strengths of rheocast 6082-T6 exceeded all of the wrought alloy T6 strength targets but the elongation only managed 36% of the required minimum due to porosity, caused by incipient melting during solution heat treatment, and the presence of fine intermetallie needles in the eutectic. The yield strength of rheocast 7075 exceeded the required one and the ultimate tensile strength also managed 97% of the specification; while the elongation only reached 46% of the minimum requirement also due to incipient melting porosity caused during the solution heat treatment process.

关键词： high pressure die casting (HPDC) aluminum alloys as-cast condition T6 treatment incipient melting

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多孔陶瓷膜毛细管冷凝分离传质模型

化工学报 1999年第3期50卷 380-385页

作者：李韡许锡恩天津大学化工学院天津300072

多孔陶瓷膜在毛细管冷凝传质机理的作用下能够有效地分离吸附性气体。而毛细管冷凝膜分离传质机理的研究还很不充分,目前,文献报道仅局限于纯组分气体的传质模型研究。本文以改性氧化铝膜对乙醇-水物系的蒸气渗透分离过程为研究对象,优... 详细信息

多孔陶瓷膜在毛细管冷凝传质机理的作用下能够有效地分离吸附性气体。而毛细管冷凝膜分离传质机理的研究还很不充分,目前,文献报道仅局限于纯组分气体的传质模型研究。本文以改性氧化铝膜对乙醇-水物系的蒸气渗透分离过程为研究对象,优选出了二元气体在毛细管冷凝膜分离过程中的组分渗透系数的计算模型;建立了多孔陶瓷膜的传质模型,对蒸气渗透分离过程的模拟证实了该模型的可靠性。

关键词：多孔陶瓷膜毛细管冷凝渗透分离传质机理蒸气