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A Modified Discontinuous GalerkinMethod for Solving Efficiently Helmholtz Problems

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Communications in Computational Physics 2012年第2期11卷 335-350页

作者： Magdalena Grigoroscuta-Strugaru Mohamed Amara henri Calandra Rabia Djellouli INRIA Bordeaux Sud-Ouest Research Center Team Project Magique-3D and LMA/CNRS UMR 5142Universit´e de Pau et des Pays de l’AdourFrance BCAM Basque Center for Applied MathematicsBilbaoSpain. TOTAL Avenue LarribauPauFrance Department of Mathematics California State University Northridge and Interdisciplinary Research Institute for the SciencesIRISUSA

A new solution methodology is proposed for solving efficiently Helmholtz *** proposed method falls in the category of the discontinuous Galerkin ***,unlike the existing solution methodologies,this method requires solving(a)well-posed local problems to determine the primal variable,and(b)a global positive semi-definite Hermitian system to evaluate the Lagrange multiplier needed to restore the continuity across the element *** numerical results obtained for two-dimensional interior Helmholtz problems are presented to assess the accuracy and the stability of the proposed solution methodology.

关键词： Helmholtz equation discontinuous Galerkin plane waves Lagrange multipliers inf-sup condition waveguide problems

Convective high-speed flow and field-aligned high-speed flows explored by TC-1

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Chinese Science Bulletin 2008年第15期53卷 2371-2375页

作者： ZHANG LingQian LIU ZhenXing MA ZhiWei W. BAUMJOHANN M.W. DUNLOP WANG GuangJun WANG Xiao H. reme C. CARR Centre for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China Institute for Fusion Theory and Simulation Zhejiang University Hangzhou 310027 China Space Research Institute Austrian Academy of Sciences 68042 Graz Austria Space Sciences Division Rutherford Appleton Laboratory Chilton Didcot Oxfordshire OX11 0QX United Kingdom Centre d'Etude Spatiale des Rayonnements F-78140 Toulouse Codex France Imperial College London SW7 2BZ United Kingdom

From June 1, 2004 to October 31, 2006, a total 465 high-speed flow events are observed by the TC-1 satellite in the near-Earth region (?13 RE < x < ?9 RE, |Y |<10 RE, |Z|<5 RE). Based on the angle between the flow and the magnetic field, the high-speed flow events are further divided into two types, that is, field-aligned high-speed flow (FAHF) in the plasma sheet boundary and convective bursty bulk flow (BBF) in the center plasma sheet. Among the total 465 high-speed flow events, there are 371 FAHFs, and 94 BBFs. The CHF are mainly concentrated in the plasma sheet, the intersection angle between the flow and the magnetic field is larger, the magnetic field intensity is relatively weak. The FHF are mainly distributed near the boundary layer of the plasma sheet, the intersection angle between the flow and magnetic field is smaller, and the magnetic field intensity is relatively strong. The convective BBFs have an important effect on the substorm.

关键词：高速流对流磁场地球科学

Response of soil mite abundance and diversity to a monospecific timber Tectona grandis plantation in Ivory Coast

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Current Zoology 2013年第5期59卷 633-643页

作者： Julien Kouadio N'DRI henri Marc ANDRE Jan LAGERLOEF Jerome Ebagnerin TONDOH Thierry HANCE UFR des Sciences de la Nature/Centre de Recherche en Ecologie Universit6 d'Ab0bo-Adjam6 02 BP 801 Abidjan 02 C6te d'Ivoire Mus6e royal de l'Afrique centrale Leuvensesteenweg 13 B-3080 Tervuren Belgium Swedish University of Agricultural Sciences (SLU) Dept. of Ecology EO.Box 7044 SE-750 07 Uppsala Sweden CIAT-TSBF Institut d'Economie Rurale CRRA de Sotuba Laboratoire Sol-Eau-Plante c/o Icraf Sahel BPE 5118 Bamako Mali Universite Catholique de Louvain Biodiversity Research Center Earth and Life Institute Place Croix du Sud 4 B-1348 Lou-vain-la-Neuve Belgium

This study aims to assess the impact of monospecificTectona grandisforest plantation on the soil mite abundance and diversity. To achieve these objectives, two sites situated in Ivory Coast were investigated. The first, a primary forest was characterized by a very weak human activities whereas the second, a teak plantation was characterized by a high disturbance performed during the planting. After extracting, sorted and description, 116 mite species were described in the two sites. Mite densities were lower in teak plantation and also higher in the litter and decreased to the depth in both sites. Species richness recorded in teak plantation (52 species) was significantly lower compared to primary forest (98 species). The same trend was observed for Oribatida but not for Gamasida. The lower Oribatida (5 vs. 17) and higher Oribatida (24 vs. 41) were recorded respectively in teak plantation and primary forest. Mite Shannon index and evenness were significantly different between sites. High Jaccard index values and the appearance of exclusive species in both habitats showed that the sites are very distinct. Total number of species recorded corresponded to 58%–63% of the total number of species estimated by ACE and Chao 1&2 estimators, indicating that the sampling effort was not sufficient. Mite abundance and diversity varied depending on the characteristics of habitats. Chemical element (Corg, Ctot, Ntot, and SOM) values were lower in teak plantation (disturbed habitat) and significantly different to primary forest in the topsoil. Apart from litter height, soil depth, pH and C/N ratio, others variables were strongly correlated to mite abundance and diversity.

关键词：土壤螨类象牙海岸人工林多样性柚木异性丰度物种丰富度

Role of the floodplain lakes in the methylmercury distribution and exchanges with the Amazon River,Brazil

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Journal of Environmental Sciences 2018年第6期30卷 24-40页

作者： Poliana Dutra Maia Laurence Maurice Emmanuel Tessier David Amouroux Daniel Cossa Patricia Moreira-Turcq henri Etcheber Universidade de Brasilia-Faculdade UnB Planaltina Area Universitaria n. 1-Vila Nossa Senhora de Fatima Planaltina 73300-000 Brasilia DF Brazil Geosciences Environnement Toulouse (GET) Observatoire Midi Pyrenees Universite de Toulouse CNRS IRD14 Avenue Edouard Belin F-32400 Toulouse France CNRS/Univ Pau & Pays Adour Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Materiaux UMR5254 F-64000 Pau Prance Universite Grenoble Alpes CP 40700 F-38058 Grenoble Cedex 9 France EPOC UMR 5805 Universite de Bordeaux I Av. des Facultes F-33405 Talence France

Seasonal variability of dissolved and particulate methylmercury（F-MeHg, P-MeHg） concentrations was studied in the waters of the Amazon River and its associated Curuai floodplain during hydrological year 2005–2006, to understand the MeHg exchanges between these aquatic systems. In the oxic white water lakes, with neutral pH, high F-MeHg and P-MeHg concentrations were measured during the rising water stage（0.70 ± 0.37 pmol/L, n = 26） and flood peak（14.19 ± 9.32 pmol/g, n = 7） respectively, when the Amazon River water discharge into the lakes was at its maximum. The lowest mean values were reported during the dry season（0.18 ± 0.07 pmol/L F-MeHg, n = 10 and 1.35 ± 1.24 pmol/g P-MeHg, n = 8）, when water and suspended sediments were outflowing from the lakes into the River. In these lakes,the MeHg concentrations were associated to the aluminium and organic carbon/nitrogen changes. In the black water lakes, with acidic pH and reducing conditions, elevated MeHg concentrations were recorded（0.58 ± 0.32 pmol/L F-MeHg, n = 16 and 19.82 ± 15.13 pmol/g PMeHg, n = 6）, and correlated with the organic carbon and manganese concentrations. Elevated values of MeHg partition coefficient（4.87 〈 Kd〈 5.08 log（L/kg） indicate that MeHg is mainly transported associated with the particulate phase. The P-MeHg enrichment detected in all lakes suggests autochthonous MeHg inputs from the sediments into the water column. The MeHg mass balance showed that the Curuai floodplain is not the source of P-MeHg for the Amazon River.

关键词： Methylmercury Water Sediment Amazon River Floodplain lakes

Nonadiabatic acceleration of plasma sheet ions related to ion cyclotron waves

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Science China(Technological Sciences) 2014年第12期57卷 2434-2440页

作者： WANG Zhi Qiang CAO Jin Bin RME henri DANDOURAS Iannis MA Yu Duan Department of Space Science and Application College of Astronautics Nanjing University of Aeronautics and Astronautics University of Toulouse UPS-OMP IRAP Toulouse 31082 France The French National Centre for Scientific Research The Research Institute in Astrophysics and Planetology Space Science Institute School of Astronautics Beihang University

The nonadiabatic acceleration of plasma sheet ions is important to the understanding of substorm energetic injections and the formation of ring current. Previous studies show that nonadiabatic acceleration of protons by magnetic field dipolarization is hard to occur at X>–10 RE because the time-scale of dipolarization(several minutes) is much larger than the gyroperiod of protons there(several seconds). In this paper, we present a case of nonadiabatic acceleration of plasma sheet ions observed by Cluster on October 30, 2006 at(XGSM, YGSM)=(-7.7, 4.7) RE. The nonadiabatic acceleration of ions is caused not by previously reported magnetospheric dipolarization but by the ultra low frequency(ULF) waves during magnetospheric dipolarization. The nonadiabatic acceleration of ions generates a new energy flux structure of ions, which is characterized by the usual energy flux increase of ions(28–80 ke V) and a concurrent energy flux decrease of ions in a lower energy range(10 e V–20 ke V). These new observations constitute a complete physical picture: The lower energy ions absorb the wave energy, and thus get accelerated to higher energy. We use a nonadiabatic model to interpret the ion energy flux variations. Both analytic and simulation results are in good agreement with the observations. This indicates that the nonadiabatic acceleration associated with ULF waves superposed on dipolarized magnetic field is an effective mechanism for ion energization in the near-Earth plasma sheet. The presented energy flux structures can be used as a proxy to identify the similar dynamic process.

关键词：离子回旋波等离子体片非绝热能量通量加速度高能注入时间尺度能量范围

高能电子爆发与绕月卫星表面电位大幅下降的联动效应

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地球物理学报 2016年第10期59卷 3533-3542页

作者：王馨悦张爱兵荆涛 H.reme 孔令高张珅毅李春来中国科学院国家空间科学中心北京100190 天基空间环境探测北京市重点实验室北京100190 法国国家科研中心法国图卢兹31028 中国科学院国家天文台北京100012

"嫦娥"一号、二号绕月飞行经历地球磁尾边界层区域时,分别在2007年11月26日—2008年2月5日和2010年10月3日—2011年2月28日,发现了15次月球轨道0.1~2 MeV电子急剧增加(Bursts of 0.1~2 MeV Energetic Electrons,BEE),卫星周围等离子体... 详细信息

"嫦娥"一号、二号绕月飞行经历地球磁尾边界层区域时,分别在2007年11月26日—2008年2月5日和2010年10月3日—2011年2月28日,发现了15次月球轨道0.1~2 MeV电子急剧增加(Bursts of 0.1~2 MeV Energetic Electrons,BEE),卫星周围等离子体离子加速的现象.统计研究表明,这类现象发生在稳定太阳风和弱行星际磁场条件下,且无显著空间环境扰动事件发生时,离子的加速滞后于高能电子爆发,离子能量的变化与高能电子通量的时间演化正相关,地球磁鞘内侧或边界层过渡区域是该类现象的高发区,离子能量增加时卫星表面电位大幅下降可达负几千伏.为了研究高能电子爆发与绕月卫星表面电位变化的关系及其对月球表面电位的影响,本文用电流平衡法建立绕月卫星和月球表面充电模型,并假设能量电子(>2eV^2 MeV)满足幂律谱的分布,模拟急剧增加的能量电子对卫星和月球表面电位的影响.模拟结果表明,能量电子急剧增加使得绕月卫星和月球表面电位大幅下降;能量电子总流量>1011 cm-2时,绕月卫星和月球表面充电电位可达负上千伏;月球充电到大的负电位的时间仅为卫星充电时间的1/10.鉴于高能电子急剧增加事件的高发生率(~125次/年),能量电子急剧增加使得绕月卫星表面电位大幅下降的发生率应大于实测等离子体离子加速现象的发生率(~25次/年).

关键词：嫦娥一号嫦娥二号月球表面充电高能电子急剧增加事件等离子体

Assessment of water body change and sedimentation rate in Moulay Bousselham wetland, Morocco, using geospatial technologies

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International Journal of Sediment Research 2019年第1期34卷 65-72页

作者： Mounir Karim Mehdi Maanan Mohamed Maanan Hassan Rhinane henri Rueff Lahssen Baidder Hassan Ⅱ University of Casablanca Faculty of Sciences An ChockCeosciences Laboratory Universite de Nantes Institut de Geographie University of Basel Department of Environmental Sciences

Coastal lagoons have significant biodiversity and ecologic and socio-economic interest. Several resident and migratory birds live in coastal lagoons as well as fish and other aquatic biota. Over the years, lagoons worldwide have been subject to considerable sediment deposition coming especially from soil erosion due of agricultural activities, and the lagoon’s inflows have resulted in an accelerated sedimentation which can drastically affect the aquatic ecosystem balance. A new, fast, and cost-effective approach was developed, using water surface change as a proxy, to evaluate the sediment deposition rate. In the current research, this methodology was applied in the Moulay Bousselham Lagoon in Morocco, and a combination of Landsat 8 and Landsat 5 imagery acquired at four points in time over 30 years(1985-2015) was used. Following geometric correction and enhancement, the interpretation of the acquired images provided important insight on the current conditions of the water surface change using the Normalized Difference Water Index(NDWI). Several iterations were done to determine a suitable threshold for effective water surface detection. In order to validate the automatically extracted water surface features, many band combinations of Landsat and Sentinel 2 were used as references to run the accuracy assessment. The results show that the Moulay Bousselham Lagoon lost 17.60%(106 ha) of its water surface area, and 530,000 m~3 to 1,060,000 m~3 of its water volume during the last three *** water surface loss into sedimentation returned a rate of 0.58 cm/yr. These results have been confirmed by previous field work using sedimentological approaches. Proper management should be applied to sustain the vitality of this lagoon environment.

关键词： Environmental monitoring Remote sensing GIS Spatial analyst Human/nature interaction Sustainability planning

On the Flammable Limits of Gas Mixtures

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化工进展 2005年第7期24卷 822-824页

作者： henri Le Chatelier O.Boudouard Jean-paul lacoursiere.P.E. University of sherbrookesherbrooke quebec Canada

INTRODUCTIONCarbon monoxide occupies a special place among combustible gases. The high flammable limit, the slowness of its flame propagation, and the role of water vapor in its combustion all suggest a resistance to oxidation that its heat of combustion would not have allowed us to anticipate. It behaves among gases a little like aluminum among metals. We thought that it would be interesting to define its flammable conditions slightly more precisely than previously *** monoxide was prepared by decomposing sodium formiate with sulfuric acid; recovered in a small water gas holder, the gas contained 7% air at time of *** Flammable LimitsThese limits were determined in defined conditions by one of us as the most favorable for this type of test, that is, in a test tube 40 mm in diameter and 20 cm in length, with ignition by a 1-cm flame through the opening held in

关键词：气体混合物一氧化碳可燃性压力

Performance Analysis of a High-Order Discontinuous Galerkin Method Application to the Reverse Time Migration

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Communications in Computational Physics 2012年第2期11卷 660-673页

作者： Caroline Baldassari Helene Barucq henri Calandra Bertrand Denel Julien Diaz INRIA Bordeaux Research Center Project Team Magique3DAvenue de l’universite64013 Pau CedexFrance. LMA CNRS UMR 5142Universite de PauAvenue de l’universite64013 Pau CedexFrance TOTAL Avenue Larribau64000 PauFrance

This work pertains to numerical aspects of a finite element method based discontinuous *** study focuses on the Interior Penalty Discontinuous Galerkin method(IPDGM)because of its high-level of flexibility for solving the full wave equation in *** assess the performance of IPDGMthrough a comparison study with a spectral element method(SEM).We show that IPDGM is as accurate as *** addition,we illustrate the efficiency of IPDGM when employed in a seismic imaging process by considering two-dimensional problems involving the Reverse Time Migration.

关键词： Interior penalty discontinuous Galerkin method spectral element method reverse time migration seismic imaging process