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Pseudo-static stability analysis of rock slopes reinforced by passive bolts using the generalized Hoek-Brown criterion

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Journal of Rock Mechanics and geotechnical Engineering 2017年第4期9卷 659-670页

作者： Mounir Belghali Zied Saada Denis garnier Samir Maghous laboratoire de génie Civil ENIT Université de Tunis El Manar Tunis Tunisia Université Paris-Est Laboratoire Navier (UMR8205) ENPC-IFSTTAR-CNRS Marne-la-Vallée France Department of Civil Engineering Federal University of Rio Grande do Sul Av. Osvaldo Aranha 99 Porto Alegre RS 90350-190 Brazil

The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory.A pseudo-static method is adopted to account for the inertial forces induced in the rock mass by seismic *** strength properties of the rock material are described by a modified Hoek-Brown strength criterion,whereas the passive bolts are modeled as bar-like inclusions that exhibit only resistance to tensile-compressive *** advantage of the ability to compute closed-form expressions for the support functions associated with the modified Hoek-Brown strength criterion,a rotational failure mechanism is implemented to derive rigorous lower bound estimates for the amount of reinforcement strength to prevent slope *** approach is then applied to investigating the effects of relevant geometry,strength and loading parameters in light of a preliminary parametric *** accuracy of the approach is assessed by comparison of the lower bound estimates with finite element limit analysis solutions,thus emphasizing the ability of the approach to properly predict the stability conditions and to capture the essential features of deformation localization ***,the extension of the approach to account for slipping at the interface between reinforcements and surrounding rock mass is outlined.

关键词： Reinforced rock slope Modified Hoek-Brown criterion Seismic loading Limit analysis Rotational failure mechanism

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Evolution of germination strategy in the invasive species Ulex europaeus

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Journal of Plant Ecology 2017年第2期10卷 375-385页

作者： Nathalie Udo Michèle Tarayre Anne Atlan laboratoire ECOBIO UMR 6553CNRSUniversitéde Rennes 1Bâtiment 14ACampus de Beaulieu263 avenue du Général Leclerc35042 Rennes CedexFrance

Aims The study of the adaptive potential of the germination patterns of invading species enables us to identify some traits linked with their capacity to colonize new sites,and to gain a better understanding of their area of *** aim of this study is to determine the germination pattern of Ulex europaeus,a cosmopolitan invasive species,in relation to temperature and to explore its potential evolu-tion and invasiveness in a tropical region,following its introduction from *** We studied the germination pattern of ***(the com-mon gorse)to test both physical dormancy and germination capacity within the range of temperatures found in the native and invasive *** understand its germination pattern and its evolution,the rate and the speed of germination,as well as the percentage of seeds that became mouldy during the experi-ment,have been compared between a native habitat,France and a habitat into which it has been introduced,the tropical island of La *** Findings The results show that gorse seeds germinate in large quantities,pos-sess the ability to germinate under a wide range of temperatures and they confirm the physical dormancy of the seeds(caused by seed coat impermeability).The decrease in germination from 25℃ upwards,coupled with an increase in the rate of moulding help to explain its restricted distribution at altitude in tropical *** scari-fied seeds,we have not detected any difference between the two regions,neither in the percentage of germinated seeds,nor in the per-centage of mouldy ***,seeds from Reunion germinate faster at 20℃ than seeds from France and a greater number of seeds from Reunion are able to germinate without scarification(10-60%for Reunion versus 0-10%for France).These results suggest that while preserving the advantages of the native habitat,in Reunion gorse develops a strategy which favours the rapid occupation of new sites.

关键词： Ulex europaeus invasive species germination physical dormancy

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Self-organization and tunable characteristic lengths of twodimensional hexagonal superlattices of nanowires directly grown on substrates

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Nano Research 2023年第1期16卷 1606-1613页

作者： D.Yi L.Peres A.Pierrot S.Cayez R.Cours B.Warot-Fonrose C.Marcelot P.Roblin K.Soulantica T.Blon Universitéde Toulouse Laboratoire de Physique et Chimie des Nano-ObjetsUMR 5215 INSACNRSUPS135 Avenue de RangueilF-31077 Toulousecedex 4France CEMES Universitéde ToulouseCNRS29 Rue Jeanne MarvigBP 94347F-31055 ToulouseFrance laboratoire de génie Chimique Universitéde ToulouseCNRSINPUPS ToulouseFrance

The organization of nano-objects on macroscopic surfaces is a key challenge for the technological improvement and implementation of *** achieving operational functions,it is required to assemble nano-objects as controllable building blocks in highly ordered ***,we demonstrate the growth and self-organization of metallic nanowires on surfaces into hexagonal superlattices with tunable characteristic lengths depending of the stabilizing surfactants *** from a reacting mixture containing a Pt(111)substrate,a Co organometallic precursor,an amine,and an acid dissolved in a solvent,we quantify the structural evolution of superlattices of vertical single-crystalline Co nanowires on Pt,using a combined analysis of small angle neutron scattering,transmission,and scanning electron *** show the concerted steps of a spontaneous growth and self-organization of the nanowires into two-dimensional(2D)hexagonal lattice on Pt,at intervals starting from a few hours of reaction to a highly ordered superlattice at longer ***,it is shown that apart from long-chain acid and long-chain aliphatic amine pairs used as stabilizers,the combination of a long-chain aliphatic and a short-chain aromatic ligand in the synthesis can also be employed for the nanowire superlattices ***,the possibility to employ different pairs allows quantitative modulation of the nanowire arrays,such as the interwire distance and the packing fraction.

关键词： metallic nanowire array self-assembly self-organized growth Co nanowire anisotropic growth solution epitaxial growth

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Analytical Calculation of the Energy in a Permanent Magnet

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Journal of Modern Physics 2016年第16期7卷 2281-2287页

作者： Jean-Paul Yonnet Christian Chillet Hicham Allag Lotfi Chouikhi laboratoire de génie Electrique de grenoble G2E Lab Université Grenoble Alpes Grenoble France laboratoire de génie Electrique de grenoble G2E Lab CNRS Grenoble France laboratoire d’Electronique et d’Electrotechnique Industrielle Jijel University Jijel Algeria

The energy in permanent magnet is not a trivial problem because it exist two types of energy: the field energy and the demagnetizing energy. For parallelepiped shape, the magnet energy has been calculated by fully analytical expressions in 3D. The result has been obtained after four successive integrations of Arctangent and Logarithm functions. The analytically calculated energy corresponds to the demagnetization energy in the magnet. The analytical results have been compared with different terms of energy obtained by computation.

关键词： Analytical Calculation Energy Permanent Magnet

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Slope Stability Analysis: Case of the West Wall of the EMZ Pit at the Essakane gold Mine in Burkina Faso (West Africa)

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geomaterials 2023年第4期13卷 109-123页

作者： Hamma Fabien Yonli Michée Banyua Lompo Nicolas Kagambega Pierre Sawadogo Ecole Supérieure d’Ingénierie Universitéde Fada N’Gourma Fada N’Gourma Burkina Faso laboratoire de Physique et de Chimie de l’Environnement Université Joseph KI-ZERBO Ouagadougou Burkina Faso Mine Service Technique IAMGOLD ESSAKANE SA Ouagadougou Burkina Faso laboratoire géosciences et Environnement Ouagadougou Burkina Faso

Knowledge of the state of stability of mining pits is both a basic condition, an essential axis and a safety benchmark for mining operations. This stability is largely based on the knowledge of the rock mass sheltering the mining works and this requires a perfect characterization of all of its structural formations through mapping (manual or digital). The families of discontinuities, namely family 1 (bedding), family 2 (Joint 2) and family 3 (Joint 1) obtained through structural mapping in the Essakane open pit mine, made it possible to analyze the failure modes at the origin of rock instabilities. The respective dips of these different directional families are: 77˚ - 85˚/N 058˚ - 068˚, 66˚ - 74˚/N 133˚ - 143˚, 25˚ - 35˚/N115˚ - 130˚. An average safety factor of 4.3 was estimated for the area with a quality of the rock mass (RMR) estimated at 47. The results obtained reflect on the one hand the risks of instability associated with the quality of the rock mass studied and on the other hand highlights the state of stability of the study area.

关键词： Stability Cartography Discontinuities Safety Factor Essakane

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Tribological response of an epoxy matrix filled with graphite and/or carbon nanotubes

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Friction 2017年第2期5卷 171-182页

作者： M.M.SAKKA Z.ANTAR K.ELLEUCH J.F.FELLER laboratoire de génie des Matériaux et Environnement ENIS Université de Sfax Sfax BP.1173-3038 Tunisia Smart Plastics group European University of Brittany(UEB) LIMATB-UBS Lorient 56321 France

Reinforced polymer-matrix composites are widely used under sliding contact conditions in various boating and automotive *** this paper,the friction and wear of bulk epoxy and carbon filler reinforced epoxy composites have been investigated using a pin-on-disc *** effect of different fillers on the tribological behavior of an epoxy has been studied using treated and untreated carbon nanotubes,graphite,and a mixture of graphite and carbon *** addition greatly enhances the tribological properties of the epoxy resin,by reducing the friction coefficient and the wear *** addition,it was found that the treated carbon nanotubes/epoxy composites have the best tribological ***,a correlation between contact temperature and friction coefficient is *** the wear mechanisms were determined by scanning electronic microscopy.

关键词： epoxy composites carbon nanotubes wear friction temperature

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Impact of the Inlet Flow Angle and Outlet Placement on the Indoor Air Quality

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Fluid Dynamics & Materials Processing 2024年第11期20卷 2603-2616页

作者： Ikram Mostefa Tounsi Mustapha Boussoufi Amina Sabeur Mohammed El ganaoui laboratoire des Sciences et Ingénierie Maritimes Facultéde Génie Mécanique.Universitédes Sciences et de la Technologie d’Oran Mohammed BoudiafBP 1505 El M’NaouerOran31000Algérie laboratoire LERMAB IUT Longwy Universitéde LorraineNancy54000France

This study aims to optimize the influence of the inlet inclination angle on the Indoor Air Quality(IAQ),heat,and temperature distribution in mixed convection within a two-dimensional square cavityfilled with an air-CO_(2)*** air-CO_(2)mixture enters the cavity through two inlet openings positioned at the top wall,which is set at the ambient temperature(TC).Three values of the Reynolds numbers,ranging from 1000 to 2000,are considered,while the Prandtl number is kept constant(Pr=0.71).The temperature distribution and streamlines are shown for Rayleigh number(Ra)equal to 104,three inlet inclination anglesϕ(0,π/6 andπ/4)and three CO_(2)concentrations values(1500,2500,3500 ppm)applied at both hot vertical walls(maintained at a constant temperature TH).Afinite volume method is used under the assumption of two-dimensional laminarflow to solve the NavierStokes and energy *** results indicate that inlet inclination angle has an impact on the indoor air quality(IAQ),which,in turn,affects the heat transfer distribution and thermal comfort within the cavity.

关键词： Mixed convection air-CO_(2) mixture inlet inclination angles laminarflow indoor air quality

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Long Term Evaluation of green Vegetation Cover Dynamic in the Atacora Mountain Chain(Togo) and its Relation to Carbon Sequestration in West Africa

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Journal of Mountain Science 2015年第4期12卷 921-934页

作者： Fousseni FOLEgA Yao Agbélessessi WOEgAN Dourma MARRA Kperkouma WALA Komlan BATAWILA Jean Leonardo SEBURANgA ZHANg Chun-yu PENg Dao-li ZHAO Xiu-hai Koffi AKPAgANA Université de Lomé Laboratoire de botanique et écologie végétale Faculté des Sciences The Key Laboratory for Forest Resources & Ecosystem Processes of Beijing Beijing Forestry University Department of Biology Faculty of Science National University of Rwanda

The research was done in the Atacora Mountain chain in Togo which tended to assess the change of vegetation cover during a 24-year *** also aims to evaluate the dynamic of the net primary productivity(NPP) of the living plants over the same *** Landsat imagery covering three different periods(1987, 2000, and 2011) was pre-processed to correct atmospheric and radiometric parameters as well as gapfilling the 2011 SCL-off ***, the vegetation indices such as NDVI(normalized difference vegetation index), SR(simple ratiovegetation index), SAVI(soil-adjusted vegetation index), and CASA(carnegie- ames- stanford approach)model for NPP were applied on these images after masking the study *** results showed a quiet decrease in the vegetation *** vegetation loss was more significant from 2000 to 2011 than from1987 to 2000, and anthropogenic activities can be deemed as the main cause of the vegetation *** biomass assessment by NPP computation also showed a decrease over the *** to the change of the vegetation cover, the ecosystem net productivity was very low in 2011 compared to 2000 and *** seems that the general health condition of thevegetation, including its potentiality in carbon sinking,was negatively affected in this area, which has already been under threatened.A perpetual monitoring of these ecosystems by means of efficient techniques could enhance the sustainable management tools of in the framework of reducing emissions from deforestation and forest degradation(REDD).

关键词： Vegetation cover NPP Carbon sinking Biomass Togo

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Pressure-broadened atomic Li(2s-2p) line perturbed by ground neon atoms in the spectral wings and core

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Chinese Physics B 2017年第7期26卷 67-74页

作者： Sabri Bouchoucha Kamel Alioua Moncef Bouledroua Physics Department Badji Mokhtar University laboratoire de Physique de la Matière et du Rayonnement Chérif Messaidia University laboratoire de Physique des Rayonnements Badji Mokhtar University

Full quantum calculations are performed to investigate the broadening profiles of the atomic lithium Li（2s-2p） resonance line induced by interactions with ground Ne（2s^22p^6） perturbers in the spectral wings and core. The X^2Σ~＋, A^2Π,and B^2Σ~＋ potential-energy curves of the two first low lying Li Ne molecular states, as well as the corresponding transition dipole moments, are determined with ab initio methods based on the SA-CASSCF-MRCI calculations. The emission and absorption coefficients in the wavelength range 550-800 nm and the line-core width and shift are investigated theoretically for temperatures ranging from 130 K to 3000 K. Their temperature dependence is analyzed, and the obtained results are compared with the previous experimental measurements and theoretical works.

关键词： pressure broadening emission and absorption coefficients linewidth lineshift

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Electron Backscattered Diffraction of Transgranular Crack Propagation in Soft Steel

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Chinese Physics Letters 2007年第6期24卷 1759-1762页

作者： A. Boumaiza T. Baudin N. Rouag R. Penelle laboratoire Microstructures et Defauts Universit6 Mentouri Constantine Algdrie laboratoire de Physico-Chimie de l'Etat Solide UMR CNRS 8648 Paris-Sud Orsay France

We consider the crack propagation in a soft steel sheet during the formation. The drawability is considered in relation with the structural anisotropy, the mechanical behaviour is related to both the grain morphology and the texture. The structure heterogeneity could lead to the apparition of micro-cracks. The results show the texture effect on the crack propagation and on the crack arrest in soft steel during the formation. The EBSD technique allows to show that the adjustment of the grain orientation from the initial main component {111}（112） towards the deformation orientation {111}（110） incites a trans-granular crack through a grain with initial {111}（112） orientation in a globally ductile material. It is the presence of grains with {111}（110） orientation which permits the closing of micro-cracks.

关键词： INITIATION gROWTH

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