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A set of ecosystem service indicators for European grasslands based on botanical surveys

Grassland Research 2024年第1期3卷 43-56页

作者： Simon Taugourdeau Frédérique Louault Alice Michelot-Antalik samir messad François Munoz Denis Bastianelli Pascal Carrère Sylvain Plantureux CIRAD UMR SELMETMontpellierFrance CIRAD INRAEInstitut AgroSELMETUniversitéMontpellierMontpellierFrance INRAE VetAgro Sup UREPUniversitéClermont AuvergneClermont-FerrandFrance INRAE LAEUniversitéde LorraineNancyFrance Laboratoire interdisciplinaire de physique Grenoble Alpes University HospitalGrenobleFrance

Background:Grasslands provide a wide range of ecosystem services(ESs).However,there is currently no method for easily diagnosing the level of ESs *** aim was to develop ES indicators based on botanical surveys,which are readily available data and integrative of grassland spatiotemporal ***:Based on academic knowledge and expertise,we identiﬁed several simple vegetation criteria that we aggregated using a multicriteria analysis tool to construct indicators of the level of ESs provided by *** this study,the indicators were calculated from over 2000 botanical surveys spread over a wide biogeographical ***:Analyses of correlation between the various indicators show that“forage supply”and“diversity conservation”were not correlated.“Forage availability”and“nitrogen availability for the vegetation”were positively linked together and negatively linked to the robustness of the plant community to extreme events.A temporal approach highlights that the“biodiversity conservation”score decreased from 1970 to 2010 and that“nitrogen availability for the vegetation”was lower in 1970 and 1980 than in 2000 and ***:These results show that our aggregation method based on a large data set of botanical surveys could be appropriate for studying temporal dynamics of ESs.

关键词： biodiversity conservation ecosystem resilience environmental modelling forage functional traits meadows nitrogen availability plant communities

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Stabilization and Synchronization of Discrete-time Fractional Chaotic Systems with Non-identical Dimensions

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Acta Mathematicae Applicatae Sinica 2021年第3期37卷 523-538页

作者： samir BENDOUKHA Department of Electrical Engineering College of EngineeringYanbuTaibah UniversitySaudi Arabia

This paper investigates the stabilization and synchronization of two fractional chaotic maps proposed recently,namely the 2D fractional Hénon map and the 3D fractional generalized Hénon *** show that although these maps have non–identical dimensions,their synchronization is still *** proposed controllers are evaluated experimentally in the case of non–identical orders or time–varying *** methods are used to illustrate the results.

关键词： discrete chaos fractional discrete calculus Hénon based maps stabilization synchronization

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DUALITY OF GENERALIZED DUNKL-LIPSCHITZ SPACES

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Acta Mathematica Scientia 2017年第6期37卷 1567-1593页

作者： samir KALLEL Department of Mathematics Higher Institute of Computer Sciences and Mathematics of MonastirMonastir University5000 MonastirTunisia

Abstract The aim of this paper is to prove duality and reflexivity of generalized Lipschitz spaces ∧κα,p,q（R）, α ∈R and 1≤〈 p, q ≤∞, in the context of Dunkl harmonic analysis.

关键词： Dunkl operator duality Herz spaces heat transform Dunkl transform gen-eralized Dunkl-Lipschitz spaces

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The effects of exhaust air vent location on thermal comfort inside a residential building equipped with an evaporative cooling system

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Building Simulation 2021年第4期14卷 1063-1075页

作者： rmin Saraei samir Farid Moujaes Department of Mechanical Engineering College of EngineeringUniversity of Nevada Las VegasLas VegasNV89154USA

The location of exhaust air vents of an evaporative cooling system can have significant effects on providing thermal comfort and controlling humidity, temperature and air distribution in buildings. In the current study, four different strategies have been evaluated for exhaust air vent locations to provide the optimum thermal comfort inside a typical residential house. This study provides a numerical solution for temperature and relative humidity profiles in the residential house and within the living space in each room typically at a height of 1.8 m or less. By evaluating different exhaust air vent locations in a room, the best strategy(ies) to provide more appropriate thermal comfort condition and obtained and as a conclusion, the exhaust vents should be located on furthest wall away from the entrance of the room and in the middle. The results provided in the current study can eventually be applied in the design of evaporative cooler exhaust vent systems in residential buildings and lead to improve the performance of these systems.

关键词： thermal comfort CFD evaporative cooling system exhaust air vents

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Finite Elementθ-Schemes for the Acoustic Wave Equation

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Advances in Applied Mathematics and Mechanics 2011年第2期3卷 181-203页

作者： samir Karaa Department of Mathematics and Statistics Sultan Qaboos UniversityP.O.Box 36Al-Khod 123MuscatSultanate of Oman

In this paper,we investigate the stability and convergence of a family of implicit finite difference schemes in time and Galerkin finite element methods in space for the numerical solution of the acoustic wave *** schemes cover the classical explicit second-order leapfrog scheme and the fourth-order accurate scheme in time obtained by the modified equation *** derive general stability conditions for the family of implicit schemes covering some well-known CFL *** error estimates are *** sufficiently smooth solutions,we demonstrate that the maximal error in the L^(2)-norm error over a finite time interval converges optimally as O(h^(p+1)+∆t^(s)),where p denotes the polynomial degree,s=2 or 4,h the mesh size,and∆t the time step.

关键词： Finite element methods discontinuous Galerkin methods wave equation implicit methods energy method stability condition optimal error estimates

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Simulation and analysis of resin flow in injection machine screw

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第3期9卷 338-345页

作者： Ling-feng LI samir MEKID College of Mechanical and Energy Engineering Zhejiang University Hangzhou 310027 China School of Mechanical Aerospace and Civil Engineering University of Manchester Manchester UK

A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications.

关键词： Screw Plasticity Velocity distribution Temperature distribution

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BEZIER SPLINES INTERPOLATION ON STIEFEL AND GRASSMANN MANIFOLDS

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Journal of Computational Mathematics 2024年第6期42卷 1554-1578页

作者： Ines Adouani Chafik samir Department of Mathematics University of SousseTunisia LIMOS-CNRS University of Clermont AuvergneFrance

We propose a new method for smoothly interpolating a given set of data points on Grassmann and Stiefel manifolds using a generalization of the De Casteljau *** that end,we reduce interpolation problem to the classical Euclidean setting,allowing us to directly leverage the extensive toolbox of spline *** interpolated curve enjoy a number of nice properties:The solution exists and is optimal in many common *** applications,the structures with respect to chosen Riemannian metrics are detailed resulting in additional computational advantages.

关键词： Optimization B´ezier spline Curve fitting Grassmann manifolds Stiefel manifolds Canonical metrics

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Spatial Variability and Cartography of Maximum Annual Daily Rainfall under Different Return Periods in Northern Algeria

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Journal of Mountain Science 2015年第6期12卷 1403-1421页

作者： MEDDI Mohamed TOUMI samir National High School of Hydraulic (ENSH)

The estimation of precipitation quantiles has always been an area of great importance to meteorologists, hydrologists, planners and managers of hydrotechnical infrastructures. In many cases, it is necessary to estimate the values relating to extreme events for the sites where there is little or no measurement, as well as their return periods. A statistical approach is the most used in such cases. It aims to find the probability distribution that best fits the maximum daily rainfall values. In our study, 231 rainfall stations were used to regionalize and find the best distribution for modeling the maximum daily rainfall in Northern Algeria. The L-moments method was used to perform a regionalization based on discordance criteria and homogeneity test. It gave rise to twelve homogeneous regions in terms of LCoefficient of variation(L-CV), L-Skewness(L-CS) and L-Kurtosis(L-CK). This same technique allowed us to select the regional probability distribution for each group using the Z statistic. The generalized extreme values distribution(GEV) was selected to model the maximum daily rainfall of 10 groups located in the north of the steppe region and the generalized logistic distribution(GLO) for groups representing the steppes of Central and Western Algeria. The study of uncertainty by the bias and RMSE showed that the regional approach is acceptable. We have also developed maximum daily rainfall maps for 2, 5, 10, 20, 50 and 100 years return periods. We relied on a network of 255 rainfall stations. The spatial variability of quantiles was evaluated by semi-variograms. All rainfall frequency models have a spatial dependence with an exponential model adjusted to the experimental semi-variograms. The parameters of the fitted semi-variogram for different return periods are similar, throughout, while the nugget is more important for high return periods. Maximum daily rainfall increases from South to North and from West to East, and is more significant in the coastal areas of ea

关键词： Annual maximum daily rainfall Regionalisation L-moments Mapping Northern Algeria

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Re-evaluation of several heavy metals removal by natural limestones

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Frontiers of Chemical Science and Engineering 2014年第4期8卷 418-432页

作者： Ali SDIRI samir BOUAZIZ Laboratory of Water Energy and Environment National Engineering School University of Sfax Sfax 1173-3038 Tunisia

Different treatment technologies have been efficiently applied to remove heavy metals from waste- water. Efforts have been made to find out the most economic water treatment technology by using low cost and easily accessible natural materials. On the other hand, heavy metals are the most threatening groundwater contaminants because of their toxicity and harmful effects on human and biota. This review discusses the use of natural geological materials for heavy metal removal in aqueous systems. Special attention has been devoted to natural limestone through a systematic inventory of relevant published reports. The removal of toxic metals may include different mechanisms （e.g., physisorption, chemisorptions, precipitation, etc.）, depending on the physico-chemical properties of the material and the removed metal. Sorption of toxic metals （e.g., Pb, Cu, Cd, Zn, Cr, Hg, etc.） onto natural limestone involved precipitation of metal carbonate as a predominant removal process, but often subordinated by adsorption and ion exchange, depending on the physico-chemical properties of the studied limestone.

关键词： limestone heavy metals sorption waste-water passive treatment technology

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Numerical study on discharge characteristics influenced by secondary electron emission in capacitive RF argon glow discharges by fluid modeling

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Chinese Physics B 2018年第2期27卷 415-422页

作者：赵璐璐刘悦 Tagra samir Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Ministry of Education) School of PhysicsDalian University of Technology School of Information Science and Engineering Dalian Polytechnic University

A one-dimensional（1D） fluid model of capacitive RF argon glow discharges between two parallel-plate electrodes at low pressure is employed. The influence of the secondary electron emission on the plasma characteristics in the discharges is investigated numerically by the model. The results show that as the secondary electron emission coefficient increases,the cycle-averaged electric field has almost no change; the cycle-averaged electron temperature in the bulk plasma almost does not change, but it increases in the two sheath regions; the cycle-averaged ionization rate, electron density, electron current density, ion current density, and total current density all increase. Also, the cycle-averaged secondary electron fluxes on the surfaces of the electrodes increase as the secondary electron emission coefficient increases. The evolutions of the electron flux, the secondary electron flux and the ion flux on the powered electrode increase as the secondary electron emission coefficient increases. The cycle-averaged electron pressure heating, electron Ohmic heating, electron heating, and ion heating in the two sheath regions increase as the secondary electron emission coefficient increases. The cycle-averaged electron energy loss increases with increasing secondary electron emission coefficient.

关键词： RF glow discharge secondary electron emission fluid model

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