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Performance Back-deduction from a Loading to Flow Coefficient Map:Application to Radial Turbine

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Journal of Thermal Science 2012年第6期21卷 509-517页

作者： xavier CARBONNEAU Nicolas BINDER Université de Toulouse Institut Supérieur de l'Aéronautique et de l'Espace(ISAE)10avenue Edouard Belin BP 54032 31400 ToulouseFrance

Radial turbine stages are often used for applications requiring off-design operation,as turbocharging for *** off-design ability of such stages is commonly analyzed through the traditional turbine map,plotting the reduced mass-flow against the pressure-ratio,for reduced-speed ***,some alternatives are possible,such as the flow-coefficient(Ψ)to loading-coefficient(φ)diagram where the pressure-ratio lines are actually straight lines,very convenient property to perform prediction.A robust method re-creating this map from a predicted Ψ-φ diagram is *** work has shown that this back-deduction quality,without the use of any loss models,depends on the knowledge of an intermediate pressure-ratio.A modelization of this parameter is then *** comparison with both experimental and CFD results is presented,with quite good agreement for mass flow rate and rotational speed,and for the intermediate pressure *** last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the Ψ-φ *** this improvement,the back-deduction method of the classical map is structured,applied and evaluated.

关键词： Radial turbine off-design flow coefficient load coefficient performance

WTR:A Reputation Metric for Distributed Hash Tables Based on a Risk and Credibility Factor

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Journal of Computer Science & Technology 2009年第5期24卷 844-854页

作者： xavier Bonnaire Erika Rosas Departamento de Informatica Universidad Tecnica Federico Santa MariaValparaisoChile Laboratoire d'Informatique de Paris 6 Universite Pierre et Marie CurieCNRS UMR 7606 INRIA REGALParisFrance

The growing number of popular peer to peer applications during the last five years has implied for researchers to focus on how to build trust in such very large scale distributed systems. Reputation systems have shown to be a very good solution to build trust in presence of malicious nodes. We propose in this paper a new metric for reputation systems on top of a Distributed Hash Table that uses a notion of risk to make the applications aware of certain behaviours of malicious nodes. We show that our metric is able to significantly reduce the number of malicious transactions, and that it also provides very strong resistance to several traditional attacks of reputations systems. We also show that our solution can easily scale, and can be adapted to various Distributed Hash Tables.

关键词： peer to peer reputation system risk evaluation

Natural enemies depend on remnant habitat size in agricultural landscapes

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Journal of Forestry Research 2015年第2期26卷 469-477页

作者： Mainara xavier Jordani erica Hasui Vinicius xavier da Silva Laboratorio de Ecologia Animal Departamento de Zoologia e BotanicaUniversidade Estadual Paulista-UNESPRua Cristovao Colombo2265Jardim NazarethSao Jose Do Rio PretoSP CEP 15054-000Brazil Laboratorio de Ecologia de Fragmentos do Sul de Minas Gerais-ECOFRAG Instituto Ciencias da NaturezaUniversidade Federal de Alfenas-UNIFAL–MGRua Gabriel Monteiro da Silva700CentroAlfenasMG CEP 37130-000Brazil

In recent decades,the consequences of habitat fragmentation have been of growing concern,because it is particularly important to understand how fragmentation may affect biodiversity,an ecological *** tested two hypotheses：（1） that natural fragment size in agricultural landscapes indirectly affects the herbivore through effects on natural predator populations;and（2） predator activity into the crop reduces along the distance from the natural fragment *** 2008 and 2009,we conducted our study in seven forest remnants and in surrounding coffee plantations（fragments ranged from 6 to 105 ha,mean 49.28 ± 36.60 ha） in Southern Minas Gerais,*** were sampled by point counts,and insect predation was evaluated by using an artificial insect model（Koh and Menge 2006）.Our results suggest that although there were many potential predators（e.g.,wasps,ants,birds,and mammals）,birds were the most important taxon *** covariance analysis supported the hypothesis that patch size affected the number of larvae predation by overall taxi,but there was no support for a distance *** findings suggest that natural enemies’ ecological service（mainly from birds） declined with remnant reduction,which has implications not only for human welfare,but also in strengthening the economic justifications for conserving the remaining natural habitats and biodiversity in agricultural landscapes.

关键词： Ecosystem service Fragmentation Isolation Insectivore Predation

The application of extended modified Lambert Beer model for measurement of blood carboxyhemoglobin and oxyhemoglobin saturation

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Journal of Innovative Optical Health Sciences 2014年第3期7卷 108-114页

作者： Audrey Huong xavier Ngu Department.of Electronic Engineering Faculty of Electrical and Electronic Engineering Uiniversity Tun Hussein Onn Malaysia Batu Pahat 86400 JohorMalaysia Department of Communication Engineering Faculty of Electrical and Electronic Engineering University Tun Hussein Onn Malaysia Batu Pahat 86400 JohorMalaysia

This work presents the use of extended Modified Lambert Beer(MLB)model for accurate andcontinuous monitoring of percent blood carboxyhemoglobin(COHb)(SCO)and oxyhemoglobin(OxyHb)saturation(SO,)via a fitting *** quantification technique is based on theabsorption characteristics of hemoglobin derivatives in the wavelength range of 520-600 nm togive the best estimates of the required parameters.A comparison of the performance of the developed model and MILB law is made using attenuation data from Monte Carlo simulations for a two-layered skin *** results revealed a lower mean absolute error of 0.4%in the valuesestimated by the developed model as compared to 10%that is given by the MILB *** studyshowed that the discussed approach is able to provide consistent and accurate measurement ofblood SO,and SCO across diferent skin pigmen tations suggesting that it may potentially be usedas an alternative means for clinical diagnosis of carbon monoxide(CO)poisoning.

关键词： Blood carboxyhemoglobin saturation carbon monoxide poisoning blood oxyhemoglobin saturation modified Lambert Beer law

Experimental investigation of flow field in a laboratory-scale compressor

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Chinese Journal of Aeronautics 2017年第1期30卷 31-46页

作者： Ma Hongwei Wei Wei xavier Ottavy Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power Engineering Beihang University Beijing 100083 China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083 China China Academy of Aerospace Aerodynamics (CAAA) Yungangxi Rd. Fengtai Dist. Beijing 100074 China Laboratoire de Mecanique des Fluides et d'Acoustique (LMFA) Groupe TurbomachinesEcole Centrale de Lyon 36 av. Guy de Collongue 69134 Ecully cedex France

The inner flow environment of turbomachinery presents strong three-dimensional, rotational, and unsteady characteristics. Consequently, a deep understanding of these flow phenomena will be the prerequisite to establish a state-of-the-art design system of turbomachinery. Currently the development of more accurate turbulence models and CFD tools is in urgent need for a high-quality database for validation, especially the advanced CFD tools, such as large eddy simulation（LES）. Under this circumstance, this paper presents a detailed experimental investigation on the 3D unsteady flow field inside a laboratory-scale isolated-rotor with multiple advanced measurement techniques, including traditional aerodynamic probes, hotwire probes, unsteady endwall static pressure measurement, and stereo particle image velocimetry（SPIV）. The inlet boundary layer profile is measured with both hotwire probe and aerodynamic probe. The steady and unsteady flow fields at the outlet of the rotor are measured with a mini five-hole probe and a single-slanted hotwire probe. The instantaneous flow field in the rotor tip region inside the passage is captured with SPIV,and then a statistical analysis of the spatial distribution of the instantaneous tip leakage vortex/flow is performed to understand its dynamic characteristics. Besides these, the uncertainty analysis of each measurement technique is described. This database is quite sufficient to validate the advanced numerical simulation with LES. The identification process of the tip leakage vortex core in the instantaneous frames obtained from SPIV is performed deliberately. It is concluded that the ensemble-averaged flow field could not represent the tip leakage vortex strength and the trajectory trace. The development of the tip leakage vortex could be clearly cataloged into three phasesaccording to their statistical spatial distribution. The streamwise velocity loss induced by the tip leakage flow increases until the splitting process is weak

关键词： Database Laboratory-scale compres-sor SPIV Tip leakage flow Tip leakage vortex

Vigilance behavior of Pyrenean chamois Rupicapra pyrenaica pyrenaica:Effect of sex and position in the herd

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Current Zoology 2010年第2期56卷 232-237页

作者： Antoni DALMAU Alfred FERRET xavier MANTECA Irta Finca Camps i Armet s/n Monells Universitat Autònoma de Barcelona School of Veterinary Science Departament de Ciència Animal i dels Aliments

The Pyrenean chamois Rupicapra pyrenaica pyrenaica is a mountain-dwelling ungulate with an extensive presence in open areas. Optimal group size results from the trade off between advantages （a reduction in the risk of predation） and disadvantages （competition between members of the herd） of group living. In addition, advantages and disadvantages of group living may vary depending on the position of each individual within the herd. Our objective was to study the effect of central vs. peripheral position in the herd on feeding and vigilance behavior in male and female Pyrenean chamois and to ascertain if a group size effect existed. We used focal animal sampling and recorded social interactions when a focal animal was involved. With males, vigilance rate was higher in the central part of the group than at the periphery, probably due to a higher density of animals in the central part of the herd and a higher probability of being disturbed by conspecifics. With females, vigilance rate did not differ according to position in the herd. Females spent more time feeding than males, and males showed a higher frequency of the vigilance behavior than females. We did not observe a clear relationship between group size and vigilance behavior. The differences in vigilance behavior might be due to social interactions

关键词： Antagonistic interactions Group size Position Pyrenean chamois Sex Vigilance

Hydrolysis of Urea to Produce Ammonia Dircio Francisco xavier Fatima Ximenes

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Hydrolysis of Urea to Produce Ammonia Dircio Francisco Xavie...

作者： Dircio Francisco xavier Fatima Ximenes（弗朗西斯科）华东理工大学

学位级别：硕士

氮氧化物（NOx）引起了巨大的环境问题,是目前世界上最大的环境污染物之一,随着对NOx法规的逐步收紧,世界各国都在积极开展减少NOx污染的研究。目前已开发利用了多种技术,其中选择性催化还原（SCR）和选择性非催化还原（SNCR）具有较高... 详细信息

氮氧化物（NOx）引起了巨大的环境问题,是目前世界上最大的环境污染物之一,随着对NOx法规的逐步收紧,世界各国都在积极开展减少NOx污染的研究。目前已开发利用了多种技术,其中选择性催化还原（SCR）和选择性非催化还原（SNCR）具有较高的脱硝效率。在SCR和SNCR工艺中,还原剂被注入烟气中,将NOx还原为无害氮（N2）。目前最常用的还原剂是氨（NH3）。尿素催化水解制氨在氨基脱氮过程中起着重要作用。本论文的目标有三个。首先,对尿素水解的催化剂进行筛选,其中均相催化剂表现出了良好的性能,因此本文用选择该类催化剂来进行尿素催化水解反应,然后尿素水解的转化率采用滴定法来进行分析。第二是设计了四因素,三水平Box-Behnken实验,结合响应面法对工艺条件进行优化,研究反应温度,反应时间,反应压力和催化剂用量对尿素水解制氨的影响及其交互作用。建立了尿素水解率的相关模型。第三是采用物料平衡方程,热量平衡方程,化学平衡方程及相平衡方程组成的非线性方程组来构建开口体系内尿素水解过程的热力学模型和动力学模型,并引入修正的Lewis-Randall方程和修正的Herry方程来描述水解反应器内NH3-CO2-H2O-（NH2）2CO（ACWU）四元多自由度气液平衡关系,气液两相的非理想性则分解采用PR状态方程和扩展UNIQUAC模型进行修正。结果表明,采用催化活性较好的乙酸钠（7g）催化剂对工艺条件进行优化,响应面法最优化的合成条件为;反应温度160℃,反应时间4h,反应压力0.4MPa和催化剂用量0.034wt%,在此工艺条件下尿素水解的转化率为98.620%,同时建立了尿素水解制氨的二次数学模型,该模型对实验结果有良好的预测作用。

关键词：尿素水解制氨热力学动力学

Ionic thermoelectric materials and devices

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Journal of Energy Chemistry 2021年第10期30卷 88-103,I0003页

作者： Dan Zhao Alois Würger xavier Crispin Laboratory of Organic Electronics Linkoping UniversityNorrkoping 60247Sweden Univ.Bordeaux&CNRS LOMA(UMR 5798)F-33405 TalenceFrance Wallenberg Wood Science Center ITNLinköping UniversityNorrköpingSweden

The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into *** main challenge in practical applications for thermoelectrics is the high cost from both materials and ***,breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature *** charging voltage is internally from the ionic Seebeck effect of the electrolyte between two *** electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric *** ionic thermoelectric materials are composed of abundant elements,and they can generate hundreds of times larger thermal voltage than that of electronic *** emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices,and triggers a renewed interest for ionic *** this review,we summarize the state of the art in the new field of ionic thermoelectrics,from the driving force of the ionic thermodiffusion to material and application *** present a general map of ionic thermoelectric materials,discuss the unique characters of each type of the reported electrolytes,and propose potential optimization and future topics of ionic thermoelectrics.

关键词： Electrolytes Soret effect Thermodiffusion Thermal energy conversion

Selective and taxon-dependent effects of semi-feral cattle grazing on tree regeneration in an old-growth Mediterranean mountain forest

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Forest Ecosystems 2020年第1期7卷 128-140页

作者： xavier Fortuny Christopher Carcaillet Sandrine Chauchard Ecole Pratique des Hautes Etudes(EPHE) PSL University75014 ParisFrance Laboratoire d’ cologie des Hydrosystèmes Naturels et Anthropisés(UMR5023 CNRS UniversitéLyon 1ENTPE)69622 VilleurbanneFrance Universitéde Lorraine AgroParisTechINRAEUMR Silva54000 NancyFrance

Background:In Mediterranean mountain socio-ecosystems,both grazing by livestock and the dry season may influence tree ***,the relative contributions of these drivers are poorly known,even though present and future canopy composition might result from past and present variations in climate and herbivore *** study aims to test how semi-feral cattle presence and season affect tree ***:The study was conducted using permanent plots inside and outside a cattle exclosure in an old-growth Mediterranean *** and seedlings were counted five times per year(winter,early spring,middle spring,summer,fall)and monitored over 7 ***:Semi-feral cattle exclusion increased Acer,Fagus,Ilex,Pinus,Prunus and Quercus sapling densities and increased Acer,Fraxinus,Ilex,Quercus and Sorbus seedling ***,the dry season did not exert any noticeable effects on the sapling or seedling densities of any of the studied ***:Semi-feral cattle presence may limit tree regeneration through taxon-dependent effects,which suggests that the current decrease in grazing livestock across the Mediterranean basin will modify recruitment processes and,likely,future forest ***:Semi-feral cattle presence acts as a selective driver of tree community composition.

关键词： Cattle Climate Experiment Herbivory Forest pastoralism