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UPLAND EROSION MODELING WITH CASC2D-SED

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International Journal of Sediment Research 2002年第4期17卷 265-274页

作者： pierre JULIEN,Rosalía ROJAS Engineering Research Center Colorado State University Research Associate Civil Engineering Dept. Colorado State University Professor of Civil EngineeringFortCollins CO80523 USA Fort Collins CO80523 USA

Developed at Colorado State University, CASC2D-SED is a physically-based model simulating the hydrologic response of a watershed to a distributed rainfall field. The time-dependent processes include: precipitation, interception, infiltration, surface runoff and channel routing, upland erosion, transport and sedimentation. CASC2D-SED is applied to Goodwin Creek, Mississippi. The watershed covers 21 km2 and has been extensively monitored both at the outlet and at several internal locations by the ARS-NSL at Oxford, MS. The model has been calibrated and validated using rainfall data from 16 meteorological stations, 6 stream gauging stations and 6 sediment gauging stations. Sediment erosion/deposition rates by size fraction are predicted both in space and time. Geovisualization, a powerful data exploration technique based on GIS technology, is used to analyze and display the dynamic output time series generated by the CASC2D-SED model.

关键词： Geographical Information System (GIS) Hydrologic model Soil erosion Watershed

Three-way Subsynchronous Torsional Interactions Between LCC HVDC,MMC HVDC and a Thermal Generator

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Journal of Modern Power Systems and Clean Energy 2023年第4期11卷 1331-1340页

作者： Stefan Kovacevic Dragan Jovcic pierre Rault Olivier Despouys School of Engineering University of AberdeenAberdeen AB243UEU.K. Réseau de Transport d’Électricité ParisFrance

This paper performs a study on three-way subsynchronous torsional interactions(SSTI)between a hybrid dual-infeed high-voltage direct current(HVDC)system and a nuclear *** test case is based on the French IFA2000 line commutated converter(LCC)HVDC(2 GW)and the new Eleclink modular multilevel converter(MMC)HVDC(1 GW)interacting with the Gravelines generator(1 GW).The analysis is performed by the means of the eigenvalue stability assessment on an analytical model,while the accuracy of the conclusions is verified using the detailed non-linear electromegnetic transient program(EMTP)*** study shows that the dual-infeed system may introduce higher risk of the SSTI compared with the point-to-point HVDC *** shows that MMC operating as static synchronous compensator(STATCOM)may further reduce the torsional damping at 6.3 Hz *** conclusion may be unexpected since it is known fact from literature that STATCOM has a beneficial impact on the transient performance of *** studies show that in a sequential HVDC loading,it may be beneficial to load the MMC HVDC ***,the risk of the SSTI may be minimized by changing HVDC controller gains,in particular,by increasing phaselocked-loop(PLL)gains on the LCC rectifier.

关键词： Subsynchronous torsional interaction(SSTI) eigenvalue stability hybrid dual-infeed high-voltage direct current(HVDC) line commutated converter(LCC) modular multilevel converter(MMC) nuclear generator

Adaptive control of permanent magnet synchronous machines with disturbance estimation

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控制理论与应用（英文版） 2012年第3期10卷 337-343页

作者： Hicham CHAOUI pierre SICARD Industrial Electronics Research Group School of EngineeringUniversite du Quebec a Trois-RivieresTrois-RivieresQuebecCanada

In this paper, an adaptive control scheme is introduced for permanent magnet synchronous machines （PMSMs） as an alternative to classical control techniques. The adaptive control strategy capitalizes on the machine＇s inverse dynamics to achieve accurate tracking by using an observer to approximate disturbance in the form of friction and load torque. The controller＇s output is then fed to a space vector pulse width modulation （SVPWM） algorithm to produce duty cycles for the inverter. The control scheme is validated through a set of simulations on an experimentally validated PMSM model. Results for different situations highlight its high speed tracking accuracy and high performance in compensating for friction and load disturbances of various magnitudes.

关键词： Adaptive control Speed control Observer Disturbance estimation Synchronous machine

DAM IMPACTS ON AND RESTORATION OF AN ALLUVIAL RIVER-RIO GRANDE, NEW MEXICO

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International Journal of Sediment Research 2003年第2期18卷 89-96页

作者： Gigi RICHARD,pierre JULIEN Department of Physical and Environmental Sciences Mesa State College Grand Junction CO Department of Civil Engineering Engineering Research Center Colorado State University Fort Collins CO USA USA

The impact of construction of dams and reservoirs on alluvial rivers extends both upstream and downstream of the dam. Downstream of dams, both the water and sediment supplies can be altered leading to adjustments in the river channel geometry and ensuing changes in riparian and aquatic habitats. The wealth of pre and post-regulation data on the Middle Rio Grande, New Mexico, provides an excellent case study of river regulation, channel adjustments, and restoration efforts. Cochiti Dam was constructed on the main stem of the Rio Grande in 1973 for flood control and sediment retention. Prior to dam construction, the Rio Grande was a wide, sandy braided river. Following dam construction, the downstream channel bed degraded and coarsened to gravel size, and the planform shifted to a more meandering pattern. Ecological implications of the geomorphic changes include detachment of the river from the floodplain, reduced recruitment of riparian cottonwoods, encroachment of non-native saltcedar and Russian olive into the floodplain, and degraded aquatic habitat for the Rio Grande silvery minnow. Recent restoration strategies include removal of non-native riparian vegetation, mechanical lowering of floodplain areas, and channel widening.

关键词： River morphology Effects of dams Rio Grande

All Speed Scheme for the Low Mach Number Limit of the Isentropic Euler Equations

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Communications in Computational Physics 2011年第6期10卷 1-31页

作者： pierre Degond Min Tang Institute of Mathematics of Toulouse Universite Paul Sabatier118route de Narbonne31062 Toulouse cedexFrance

An all speed scheme for the Isentropic Euler equations is presented in thispaper. When the Mach number tends to zero, the compressible Euler equations converge to their incompressible counterpart, in which the density becomes a constant. Increasing approximation errors and severe stability constraints are the main difficultyin the low Mach regime. The key idea of our all speed scheme is the special semiimplicit time discretization, in which the low Mach number stiff term is divided intotwo parts, one being treated explicitly and the other one implicitly. Moreover, the fluxof the density equation is also treated implicitly and an elliptic type equation is derivedto obtain the density. In this way, the correct limit can be captured without requesting the mesh size and time step to be smaller than the Mach number. Compared withprevious semi-implicit methods [11,13,29], firstly, nonphysical oscillations can be suppressed by choosing proper parameter, besides, only a linear elliptic equation needs tobe solved implicitly which reduces much computational cost. We develop this semiimplicit time discretization in the framework of a first order Local Lax-Friedrichs (orRusanov) scheme and numerical tests are displayed to demonstrate its performances.

关键词： Low Mach number Isentropic Euler equations compressible flow incompressible limit asymptotic preserving Rusanov scheme

Ocean-based climate actions recommended by academicians from Europe and China

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Science China Earth Sciences 2022年第8期65卷 1612-1614页

作者： Jean-pierre GATTUSO Nianzhi JIAO Laboratoire d’Océanographie de Villefranche CNRS-Sorbonne University-IddriParis75006France Carbon Neutral Innovation Reaserch Center Xiamen UniversityXiamen361005China

Ocean acidification,deoxygenation and sea level Rise impacted by global warming intertwined with anthropogenic activities have resulted in tremendous ecological losses at species,diversity and ecosystem levels,leading... 详细信息

关键词： warming climate consequences

TeV cosmic-ray proton and helium spectra in the myriad model Ⅱ

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Research in Astronomy and Astrophysics 2015年第1期15卷 15-27页

作者： Wei Liu pierre Salati Xuelei Chen National Astronomical Observatories Chinese Academy of Science University of Chinese Academy of Sciences LAPTh Universit'e de Savoie CNRS BP 110 74941 Annecy-le-Vieux France Center of High Energy Physics Peking University

Recent observations show that the spectra of cosmic ray nuclei start to harden above ～ 102 GeV, which contradicts the conventional steady-state cosmic ray model. We had suggested that this anomaly is due to the propagation effect of cosmic rays released from local young cosmic ray sources; the total flux of cosmic rays should be computed with the Myriad Model, where a contribution from sources in the local catalog is added to the background. However, although the hardening could be elegantly explained in this model, the model parameters obtained from the fit are skewed toward a region with fast diffusion and a low supernova rate in the Galaxy, in disagreement with other observations. We further explore this model in order to set up a concordant picture. Two possible improvements related to cosmic ray sources are considered. First, instead of the usual axisymmetric disk model, we examine a spiral model for the source distribution. Second, for nearby and young sources which are necessary to explain the hardening, we allow for an energy-dependent escape. We find that a major improvement comes from incorporating an energy-dependent escape time for local sources, and with both modifications not only are the cosmic ray proton and helium anomalies resolved, but also the parameters attain values in a reasonable range compatible with other analyses.

关键词： catalogs cosmic rays pulsars: general galaxies: spiral

Ad-hoc combination and analysis of heterogeneous and distributed spatial data for environmental monitoring-design and prototype of a web-based solution

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International Journal of Digital Earth 2018年第1期11卷 79-94页

作者： Stefan Wiemann pierre Karrasch Lars Bernard Chair of Geoinformatics Technische Universität DresdenDresdenGermany

With regard to a multi-dimensional and multi-facetted implementation of the vision of a Digital Earth,capabilities to combine and analyze heterogeneous spatial data sources on the web are becoming increasingly *** this article,an online system is conceptualized and implemented to facilitate spatial data analysis and decision making specifically for environmental *** supports a dynamic search and binding of suitable geoprocessing functionality with respect to the given input data and target *** patterns are used to create an application-oriented abstraction layer on top of generic geoprocessing services available on the *** an application scenario the determination and quality assessment for water body structures is *** this use case authoritative data,remote sensing imagery and citizen science data gets combined to gain a comprehensive picture of the various spatial,temporal and thematic aspects influencing the quality of inland *** prototypical implementation makes use of open standards to facilitate the integration with existing spatial data infrastructures.

关键词： Geoprocessing geoprocessing pattern water quality spatial information infrastructure

L^1-Poincaré and Sobolev inequalities for differential forms in Euclidean spaces Dedicated to Professor Jean-Yves Chemin on the Occasion of His 60th Birthday

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Science China Mathematics 2019年第6期62卷 1029-1040页

作者： Annalisa Baldi Bruno Franchi pierre Pansu Dipartimento di Matematica Università di Bologna Laboratoire de Mathématiques d'Orsay Université Paris-Sud CNRSUniversité Paris-Saclay

In this paper, we prove Poincaré and Sobolev inequalities for differential forms in L^1(R^n). The singular integral estimates that it is possible to use for L^p, p > 1, are replaced here with inequalities which go ba... 详细信息

关键词： differential forms Sobolev-Poincaré inequalities homotopy formula