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High-capacity free-space optical link in the midinfrared thermal atmospheric windows using unipolar quantum devices

Advanced Photonics 2022年第5期4卷 36-46页

作者： Pierre Didier Hamza Dely Thomas Bonazzi Olivier Spitz Elie Awwad étienne rodriguez Angela Vasanelli Carlo Sirtori Frédéric Grillot Télécom Paris Institut Polytechnique de ParisLTCIPalaiseauFrance mirSense Centre d’integration NanoInnovPalaiseau France ENS UniversitéPSLCNRSSorbonne UniversitéUniversitéde ParisLaboratoire de Physique de l’École Normale SupérieureParisFrance University of Central Florida CREOLCollege of Optics and PhotonicsOrlandoFloridaUnited States University of New Mexico Center for High Technology MaterialsAlbuquerqueNew MexicoUnited States

Free-space optical communication is a very promising alternative to fiber communication systems,in terms of ease of deployment and *** light has several features of utter relevance for free-space applications:low absorption when propagating in the atmosphere even under adverse conditions,robustness of the wavefront during long-distance propagation,and absence of regulations and restrictions for this range of wavelengths.A proof-of-concept of high-speed transmission taking advantage of intersubband devices has recently been demonstrated,but this effort was limited by the short-distance optical path(up to 1 m).In this work,we study the possibility of building a long-range link using unipolar quantum *** different detectors are used:an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared *** evaluate the maximum data rate of our link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31 *** using pulse shaping,pre-and post-processing,we reach a record bitrate of 30 Gbit s−1 for both two-level(OOK)and four-level(PAM-4)modulation schemes for a 31-m propagation link and a bit error rate compatible with error-correction codes.

关键词： free-space communication Stark-effect external modulator midinfrared photonics intersubband technology unipolar quantum devices

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Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands

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Forest Ecosystems 2021年第2期8卷 373-386页

作者： Joannie Beaulne Étienne Boucher Michelle Garneau Gabriel Magnan Geotop Research Center Université du Québec à MontréalMontréalQuébec H3C 3P8Canada Department of Geography Université du Québec à MontréalMontréalQuébec H3C 3P8Canada GRIL-UQAM Université du Québec à MontréalQuébec H3C 3P8Canada Centre d'études nordiques Université LavalMontréalQuébec G1V 0A6Canada

Background:Black spruce(Picea mariana(Mill.)BSP)-forested peatlands are widespread ecosystems in boreal North America in which peat accumulation,known as the paludification process,has been shown to induce forest growth *** continuously evolving environmental conditions(e.g.,water table rise,increasing peat thickness)in paludified forests may require tree growth mechanism adjustments over *** this study,we investigate tree ecophysiological mechanisms along a paludification gradient in a boreal forested peatland of eastern Canada by combining peat-based and tree-ring *** and oxygen stable isotopes in tree rings are used to document changes in carbon assimilation rates,stomatal conductance,and water use *** addition,paleohydrological analyses are performed to evaluate the dynamical ecophysiological adjustments of black spruce trees to site-specific water table ***:Increasing peat accumulation considerably impacts forest growth,but no significant differences in tree water use efficiency(iWUE)are found between the study ***-ring isotopic analysis indicates no iWUE decrease over the last 100 years,but rather an important increase at each site up to the 1980 s,before iWUE ***,inferred basal area increments do not reflect such ***,iWUE variations do not reflect tree ecophysiological adjustments required by changes in growing *** water table variations induce no changes in ecophysiological mechanisms,but a synchronous shift in iWUE is observed at all sites in the mid-1980 ***:Our study shows that paludification induces black spruce growth decline without altering tree water use efficiency in boreal forested *** findings highlight that failing to account for paludification-related carbon use and allocation could result in the overestimation of aboveground biomass production in paludified *** research on carbon allocation strategies is of utmos

关键词： Black spruce growth Boreal biome Carbon allocation Ecophysiological mechanisms Forested peatland Paludification Stable isotope Water use efficiency

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Multi-patch multi-group epidemic model with varying infectivity

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Probability, Uncertainty and Quantitative Risk 2022年第4期7卷 333-364页

作者： Raphaël Forien Guodong Pang Étienne Pardoux INRAE Centre INRAE PACADomaine St-Paul-Site Agroparc84914 Avignon CedexFrance Department of Computational Applied Mathematics and Operations Research George R.Brown College of EngineeringRice UniversityHoustonTX 77005US Aix Marseille University CNRSI2M13453 MarseilleFrance

This paper presents a law of large numbers result,as the size of the population tends to infinity,of SIR stochastic epidemic models,for a population distributed over distinct patches(with migrations between them)and distinct groups(possibly age groups).The limit is a set of Volterra-type integral equations,and the result shows the effects of both spatial and population *** novelty of the model is that the infectivity of an infected individual is infection age *** precisely,to each infected individual is attached a random infection-age dependent infectivity function,such that the various random functions attached to distinct individuals are *** proof involves a novel construction of a sequence of *** to invoke the law of large numbers for processes in,by using the solution of a MacKean-Vlasov type Poisson-driven stochastic equation(as in the propagation of chaos theory).We also establish an identity using the Feynman-Kac formula for an adjoint backward *** advantage of this approach is that it assumes much weaker conditions on the random infectivity functions than our earlier work for the homogeneous model in[20],where standard tightness criteria for convergence of stochastic processes were *** illustrate this new approach,we first explain the new proof under the weak assumptions for the homogeneous model,and then describe the multipatch-multigroup model and prove the law of large numbers for that model.

关键词： Stochastic epidemic model Multi-patch multi-group Varying infectivity SIR model Law of large numbers Feynman-Kac formula Poisson-driven(McKean-Vlasov type)stochastic equations Propagation of chaos

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Factors affecting the spatial distribution and breeding habitat of an insular cliff-nesting raptor community

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Current Zoology 2018年第2期64卷 173-181页

作者： Beneharo rodriguez Airam rodriguez Felipe SIVERIO Manuel SIVERIO Canary Islands' Ornithology and Natural History Group (GOHNIC) La Malecita s/n 38480 Buenavista del NorteTenerife Canary Islands Spain Department of Evolutionary Ecology Estacion Biologica de DoSana (CSIC)Avda. Americo Vespucio s/n Seville 41092 Spain

The specific spatial distribution and habitat association--strongly influenced by environmental fac- tors or competitive interactions--are major issues in ecology and conservation. We located and georeferenced nesting sites of five cliff-nesting raptors （Egyptian vulture Neophron percnopterus [a locally extinct species], common buzzard Buteo buteo, osprey Pandion haliaetus, common kes- trel Falco tinnunculus, Barbary falcon Falco peregrinus pelegrinoides）, and common raven Corvus corax on one of the most biodiverse hotspot within the Canary Islands （Teno, Tenerife）. We used generalized linear models to evaluate the factors affecting abundance, richness, and intra- and interspecific interactions. Raptor abundance increased with slope, shrub-covered area, and habitat diversity, and decreased with altitude, and forested and grassed areas. Richness increased with slope and decreased with altitude. Threatened species （osprey, Barbary falcon, and raven） occu- pied cliffs farther away from houses and roads, and more rugged areas than the non-threatened species. The models suggested that the probability of cliff occupation by buzzards, falcons, and rav- ens depended only on inter-specific interactions. Buzzard occupation increased with the distance to the nearest raven and kestrel nests, whereas falcons and ravens seek proximity to each other. Teno holds between 75% and 100% of the insular breeding populations of the most endangered species （osprey and raven）, indicating the high conservation value of this area. Our study suggests that the preservation of rugged terrains and areas of low human pressure are key factors for raptor conservation and provide basic knowledge on the community structure and habitat associations to develop appropriated management actions for these fragile island populations.

关键词： Canary Islands competitive interactions human disturbances habitat threatened species.

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Characterization of Gromov Hyperbolic Short Graphs

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Acta Mathematica Sinica,English Series 2014年第2期30卷 197-212页

作者： José Manuel rodriguez Departamento de Matemticas Universidad Carlos III de MadridAvenida de la Universidad 30

To decide when a graph is Gromov hyperbolic is,in general,a very hard *** this paper,we solve this problem for the set of short graphs（in an informal way,a graph G is r-short if the shortcuts in the cycles of G have length less than r）：an r-short graph G is hyperbolic if and only if S9r（G）is finite,where SR（G）：=sup{L（C）：C is an R-isometric cycle in G}and we say that a cycle C is R-isometric if dC（x,y）≤dG（x,y）＋R for every x,y∈C.

关键词： Short graph Gromov hyperbolicity Gromov hyperbolic graph infinite graphs geodesics

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Mapping Glacier Variations at Regional Scale through Equilibrium Line Altitude Interpolation: GIS andStatistical Application in Massif des Écrins (French Alps)

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Journal of Geographic Information System 2011年第3期3卷 232-241页

作者： étienne Cossart 不详

Glacier variation is one of the best indicators of climate change in mountainous environment. In French Alps, many temporal data are acquired by glaciologists at glaciers scale: geometrical parameters (surface area, thickness, length and front altitude) are surveyed since the end of the 19th century. Those parameters are necessary to estimate the mass-balance of glaciers and, then, an accurate temporal signal of glacier variation. However, the time-response of the glaciers can be highly variable because of the topoclimate, and more generally the local settings of the glaciers. Moreover, climatologists and hydrologists are requiring estimation of glacier variations at regional scale and not only at local scale. In this paper, we highlight that the Equilibrium Line Altitude (ELA) is a parameter prone to spatio-temporal reconstructions at regional scale. ELA can indeed be interpolated at a region scale from local data: for instance, many geographers have reconstructed spatial trends during 1980s. Here, we try to interpolate ELA from multi-dimensionnal regression analysis: ELA is explained by many local parameters (Incoming solar radiation, topographic indexes, snow-redistribution by wind, etc.). Regression model was adjusted from a spatio-temporal database of 50 glaciers, located in the Massif des écrins. ELA was estimated for each glacier thanks to the Accumulation Area Ratio (ratio = 0.65) at two stages: LIA maximum and at present. Results first show that the multiple regression analysis is efficient to interpolate ELA through space: the adjusted r2 is about 0.49 for the reconstruction during the LIA, and 0.47 at present. Moreover, the RMSE error is about 50 meters for the LIA period, 55 meters at present. Finally, a high spatial variability (standard deviation of about 150 meters) is highlighted: incoming solar radiation and snow redistribution by wind mostly explain the observed differences. We can also assess a rise of the ELA of about 250 meters during the 20th c

关键词： Glaciers Equilibrium line Interpolation GIS Massif des écrins Alps

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Small-signal Model for Dual-active-bridge Converter Considering Total Elimination of Reactive Current

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Journal of Modern Power Systems and Clean Energy 2021年第2期9卷 450-458页

作者： Juan Ramon rodriguez-rodriguez Nadia Maria Salgado-Herrera Jacinto Torres-Jimenez Nestor Gonzalez-Cabrera David Granados-Lieberman Martin Valtierra-rodriguez the Universidad Nacional Autonoma de Mexico Facultad de IngenieriaDepto.Energia Electri-ca.Av.Universidad 3000Col.UNAM CUCoyoacanCDMXMexico the Instituto de Energias Renovables Universidad Nacional Autonoma de MexicoPriv.Xochicalco s/nCol.Centro.TemixcoMorelosMexico the Instituto Tec-nologico Superior de Irapuato Carretera Irapuato-Silao km 12.5.IrapuatoGuanajuatoMexico the Universidad Autonoma de Queretaro Campus San Juan del RioRio Moctezuma 249San Juan del RioQueretaroMexico

Emerging technologies such as electric vehicles,solid-state transformers,and DC transformers are implemented using the closed-loop bi-directional dual-active-bridge(DAB)*** this context,it is necessary to have average models that provide an efficient way of tuning the proportional integral(PI)compensator parameters for large-and small-signal *** present a novel small-signal model(SSM)for DAB converter with a single closed-loop PI controller and the total elimination of reactive current(IQ=0).The method applies a modulation technique for IQ=0 and introduces a composite function in the controller while reducing the original nonlinear switching model,which allows to decrease the order of the transfer function and analyze the closed-loop *** proposed SSM is analyzed using different response time,load,and DC voltage *** simulation and experimental results demonstrate the ease of implementation and effectiveness of the proposed model with respect to other SSM techniques.

关键词： Small-signal model(SSM) dual-active-bridge(DAB)converter reactive current elimination proportional integral(PI)control

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Automatic Bone Surface Restoration for Markerless Computer-Assisted Orthopaedic Surgery

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Chinese Journal of Mechanical Engineering 2022年第1期35卷 85-90页

作者： Xue Hu Ferdinando rodriguez y Baena Mechatronics in Medicine Laboratory Imperial College LondonLondonUK

An automatic markerless knee tracking and registration algorithm has been proposed in the literature to avoid the marker insertion required by conventional computer-assisted knee surgery,resulting in a shorter and less invasive surgical ***,such an algorithm considers intact femur geometry *** bone surface modification is inevitable due to intra-operative *** mismatched correspondences will degrade the reliability of registered target *** solve this problem,this work proposed a supervised deep neural network to automatically restore the surface of processed *** network was trained on a synthetic dataset that consists of real depth captures of a model leg and simulated realistic femur *** to the evaluation on both synthetic data and real-time captures,the registration quality can be effectively improved by surface *** improvement in tracking accuracy is only evident over test data,indicating the need for future enhancement of the dataset and network.

关键词： Bone surface reconstruction Computer assisted orthopedic surgery Markerless femur tracking

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Multi-terminal DC grids: challenges and prospects

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 515-523页

作者： Pedro rodriguez Kumars ROUZBEHI Loyola University Andalucia Seville Spain

A few multi-terminal direct current(MTDC)systems are in operation around the world today. However,MTDC grids overlaying their AC counterpart might a reality in a near future. The main drivers for constructing such direct current grids are the large-scale integration of remote renewable energy resources into the existing alternative current(AC) grids, and the promotion and development of international energy markets through the socalled supergrids. This paper presents the most critical challenges and prospects for such emerging MTDC grids,along with a foreseeable technology development roadmap,with a particular focus on crucial control and operational issues that are associated with MTDC systems and grids.

关键词： HVDC systems MTDC grids Control and operation Integration of renewable energies Supergrid

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Energy model based on solar potential and the production of electrical energy through living plants’photosynthesis

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Clean Energy 2024年第3期8卷 116-126页

作者： Raymond Daniel rodriguez Martinez Department of Industrial Production Faculty of EngineeringUniversidad Metropolitana1073 CaracasVenezuela

Developing a sustainable energy model is imperative considering the current trend towards decarbonizing sectors *** this purpose,Venezuela was used as a reference to propose an energy model focused on taking advantage of plant photosynthesis through microbial-vegetable fuel cells together with an agro-photovoltaic system to enhance energy and agricultural *** production from the cells was estimated using an average power density of 264 mW/m^(2) over 4%of the areas destined for crops in the entire Venezuelan region,obtaining an annual production of 19.889 GWh/*** contrast,the energy production of the agro-photovoltaic system was modelled using PVsyst software on 50%of the area used for the cells distributed throughout the states of Anzoátegui,Guárico,Monagas and Portuguesa according to their meteorological conditions,solar irradiation and agricultural activity,resulting in 3703417 GWh/*** resulting whole system proved to be able to cover>10 times the installed electricity generation capacity at a national level and,together with the tremendous scalability of the microbial fuel cells,it shows that Venezuela has a high potential for the production and distribution of clean energy.

关键词： ecosystems microbial fuel cell microorganisms renewable sustainability

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