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Thermo-Mechanical Calculation of Printed Circuit Heat Exchanger Using Homogenization

Journal of Thermal Science 2022年第6期31卷 2309-2328页

作者： GARNIER Christophe vincent Sébastien LAMAGNERE Pierre LEJEAIL Yves CACHON Lionel CEA DESIRESNENuclear Technology DepartmentCadarache F-13108 Saint-Paul-Lez-DuranceFrance

The Finite-Element Method(FEM) is mainly used to design Compact Heat Exchanger structures. However, the narrow channel structures require fine mesh to accurately compute stress and strain. Combined with the dimensions of the overall component, this leads to an excessively large numerical model and therefore long computing time. This is especially true for transient thermal analyses, which require taking into account the full geometry. It is therefore interesting to reduce the size of the mesh. Periodic homogenization is an efficient method for achieving this goal. It can be applied to the core of the structure when periodic patterns(identified on basis of the arrangement of the channels) exist. A method based on this technique, with some improvements, is proposed in this paper for thermal loading without internal pressure. In addition to the Equivalent Homogenous Medium(EHM) replacing the periodic patterns, some explicit channels are interposed between the EHM and the cover plates. This has two advantages. The first is to smooth the transition of stiffness between the cover plates and the homogenized medium. The second one is to be able to directly compute stress and strain on the most critical channels located in this area. This paper assesses the method’s effectiveness for thermal loadings in order to conduct thermal stress analyses. First, the equivalent elastic constants of the EHM are obtained with a numerical Finite Elements Method. Then, two 2D cases using EHM are compared against a 2D explicit model(i.e. explicit geometry for the core channels). These cases are chosen to validate the EHM itself and its effectiveness for a real section of the heat exchanger. Results show very good agreement with a relative difference lower than 1%. In addition, the sensitivity to the number of layers added between the EHM and the cover plates is analysed. It is recommended interposing at least two layers of patterns to obtain converged results for the considered configuration

关键词： compact heat exchanger thermal stress finite element method homogenization

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Contact and hybrid zone hotspots and evolution of birds in the Middle East

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Progress in Natural Science:Materials International 2007年第9期17卷 1114-1118页

作者： Mansour Aliabadian Mohammad Kaboli Bahram Kiabi vincent Nijman Institute for Biodiversity and Ecosystem Dynamics Zoological MuseumUniversity of Amsterdam1090 GT AmsterdamThe NetherlandsDepartment of BiologyFaculty of SciencesFeredowsi UniversityMashadIran Department of Fishery and Environment Faculty of Natural ResourcesTehran UniversityIran Department of Biology Faculty of SciencesUniversity of Shahid BeheshtiTehranIran Institute for Biodiversity and Ecosystem Dynamics Zoological MuseumUniversity of Amsterdam1090 GT AmsterdamThe Netherlands

The Middle East is an important contact zone for a considerable number of bird taxa from the western and eastern Palearctic and from the great Saharo-Sindian desert *** WORLDMAP software,we analyzed the geographical distribution of secondary contact zones for parapatric species pairs of birds in the Middle *** identified 56 species(29 species pairs)that make contact in the Middle *** species pairs belong to three orders,***,Piciformes,and *** half(46%)of these species pairs hybridize in their contact *** contact zones occur over a large part of northern Middle East,spatially they were not evenly *** zone richness was highest in the mountain ranges south of the Caspian Sea and the *** hottest hotspots,where up to nine bird species pairs occur sympatrically,are situated in north-eastern Iran and *** discuss the relevance of these hotspots for improving our understanding of the biogeography and evolution of the avifauna in the Middle East.

关键词： contact zone hybridisation Middle East parapatry species-pairs zoogeography

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Emergency evacuation in a supermarket during a terrorist attack: towards a possible modelling of the influence of affordances on the evacuation behavior of agents in a complex virtual environment

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Journal of Safety Science and Resilience 2023年第2期4卷 139-150页

作者： Satya Lancel vincent Chapurlat Gérard Dray Sophie Martin EA 4556 EPSYLON Univ Paul Valery Montpelier 3EPSYLON EA 4556F34000MontpelierFrance Laboratoire des Sciences des Risques(LSR) IMT Mines AlesAlesFrance EuroMov Digital Health in Motion Univ MontpellierIMT Mines AlesAlesFrance

During a terrorist attack on a supermarket,the use of emergency exits is essential for effective evacuation and saving ***,people tend to ignore emergency *** behavior can lengthen evacuation times,endanger individuals,and even prove *** this context,we conducted a series of experiments to explore the links between cognition and the dynamics of human capabilities in a complex and changing *** a series of behavioral experiments and computer simulations,we found that active guidance by green flashing lights at emergency exits impacts the behavior of individuals in an emergency evacuation situation in a supermarket;this tested our hypothesis that changing the environment in turn changes the evacuation behavior of *** also show that environmental modification can help in decision-making in an emergency ***,the results of computer simulations support a possible modeling of the influence of affordances on the evacuation behavior of agents in a complexvirtual environment.

关键词： Human behavior in emergency situations environmental affordances multi-agent systems signage emergency exits supermarkets

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Anti-plane deformations around arbitrary-shaped canyons on a wedge-shape half-space:moment method solutions

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Earthquake Engineering and Engineering Vibration 2003年第2期2卷 281-287页

作者： Nazaret Dermendjian vincent W.Lee 梁建文 Department of Civil Engineering & Applied Mechanics California State UniversityNorthridgeCalifornia 91330-8347USA Assistant Professor Department of Civil& Environmental Engineering University of Southern CaliforniaLos AngelesCalifornia90089-2531USA Profcssor School of Civil Engineering Tianjin UniversityTianjin 300072China Professor

The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been *** computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals(moment method).The wave displacement fields are computed by the residual method for the cases of elliptic,circular,rounded-rectangular and flat-elliptic canyons,The analysis demonstrates that the resulting surface displacement depends,as in similar previous analyses,on several factors including,but not limited,to the angle of the wedge,the geometry of the vertex,the frequencies of the incident waves,the angles of incidence,and the material properties of the *** analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.

关键词： weighted-residual moment method wedge half-space arbitrary-shaped cicular elliptic rectangular canyons

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Biosynthesis of Callose and Cellulose by Detergent Extracts of Tobacco Cell Membranes and Quantification of the Polymers Synthesized in vitro

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Journal of Integrative Plant Biology 2010年第2期52卷 221-233页

作者： Carolina Cifuentes vincent Bulone Anne Mie C.Emons Laboratory of Plant Cell Biology Wageningen University Division of Glycoscience School of BiotechnologyRoyal Institute of TechnologyAlbaNova University Center Department of Biomolecular Systems FOM Institute for Atomic and Molecular Physics

The conditions that favor the in vitro synthesis of cellulose from tobacco BY-2 cell extracts were determined. The procedure leading to the highest yield of cellulose consisted of incubating digitonin extracts of membranes from 11-day-old tobacco BY-2 cells in the presence of 1 mM UDP-glucose, 8 mM Ca^2＋ and 8 mM Mg^2＋. Under these conditions, up to nearly 40% of the polysaccharides synthesized in vitro corresponded to cellulose, the other polymer synthesized being callose. Transmission electron microscopy analysis revealed the occurrence of two types of structures in the synthetic reactions. The first type consisted of small aggregates with a diameter between 3 and 5 nm that associated to form fibrillar strings of a maximum length of 400 nm. These structures were sensitive to the acetic/nitric acid treatment of Updegraff and corresponded to callose. The second type of structures was resistant to the Updegraff reagent and corresponded to straight cellulose microfibrils of 2-3 nm in diameter and 200 nm to up to 5 μm in length. In vitro reactions performed on electron microscopy grids indicated that the minimal rate of microfibril elongation in vitro is 120 nm/min. Measurements of retardance by liquid crystal polarization microscopy as a function of time showed that small groups of microfibrils increased in retardance by up to 0.047 nm/min per pixel, confirming the formation of organized structures.

关键词： Biosynthesis of Callose and Cellulose by Detergent Extracts of Tobacco Cell Membranes and Quantification of the Polymers Synthesized in vitro

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Fluidization and Transport of Vibrated Granular Matter:A Review of Landmark and Recent Contributions

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Fluid Dynamics & Materials Processing 2024年第1期20卷 1-29页

作者： Peter Watson Sebastien vincent Bonnieu Marcello Lappa Department of Mechanical and Aerospace Engineering University of StrathclydeGlasgowUK European Space Agency European Space Research and Technology CentreNoordwijkNetherland

We present a short retrospective review of the existing literature about the dynamics of(dry)granular matter under the effect of *** main objective is the development of an integrated resource where vital information about past findings and recent discoveries is provided in a single *** attention is paid to those works where successful synthetic routes to as-yet unknown phenomena were *** landmark results are analyzed,while smoothly blending them with a history of the field and introducing possible categorizations of the prevalent *** no classification is perfect,and it is hard to distillate general properties out of specific observations or realizations,two possible ways to interpret the existing results are defined according to the type of forcing or the emerging(ensuing)regime of *** particular,first results concerning the case where vibrations and gravity are concurrent(vertical shaking)are examined,then the companion situation with vibrations perpendicular to gravity(horizontal shaking)is *** classes are introduced as follows:(1)Regimes where sand self-organizes leading to highly regular geometrical“pulsating”patterns(thin layer case);(2)Regimes where the material undergoes“fluidization”and develops an internal multicellular convective state(tick layers case);(3)Regimes where the free interface separating the sand from the overlying gas changes inclination or develops a kind a patterned configuration consisting of stable valleys and mountains or travelling waves;(4)Regimes where segregation is produced,i.e.,particles of a given size tend to be separated from the other grains(deep containers).Where possible,an analogy or parallelism is drawn with respect to the companion field of fluid-dynamics for which the assumption of“continuum”can be applied.

关键词： Granular materials vibrations fluidization flowability symmetry breaking

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Data-Driven Approaches to Integrated Disaster Risk Management Special Issue of the 9th Conference of the International Society for Integrated Disaster Risk Management

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International Journal of Disaster Risk Science 2020年第6期11卷 693-695页

作者： vincent Lemiale Mahesh Prakash Ana Maria Cruz CSIRO Data61 Clayton SouthVIC 3169Australia Disaster Prevention Research Institute Kyoto UniversityKyoto 611-0011Japan

The 9 th Conference of the International Society for Integrated Disaster Risk Management(IDRiM)was held in Sydney on 2–4 October *** event was hosted by Data61,the data innovation hub of Australia’s National Science Agency *** IDRiM annual conference series traditionally brings together researchers and practitioners across all disciplines of disaster risk management(DRM)and the Australian instalment was no exception.

关键词： disaster traditionally Sydney

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Rolling in Nature and Robotics: A Review

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Journal of Bionic Engineering 2006年第4期3卷 195-208页

作者： Rhodri H.Armour Julian F.V.vincent Centre for Biomimetic and Natural Technologies Department of Mechanical Engineering University of Bath Bath BA2 7AY UK

This paper presents a review of recent rolling robots including Rollo from Helsinki University of Technology, Spherical Mobile Robot from the Politecnico of Bad, Sphericle from the University of Pisa, Spberobot from Michigan State University, August from Azad University of Qazvin and the University of Tehran, Deformable Robot from Ritsumeijan University, Kickbot from the Massachusetts Institute of Technology, Gravitational Wheeled Robot from Kinki University, Gyrover from Carnegie Mellon University, Roball from the Université de Sherbrooke, and Rotundus from the Angstroem Space Technology Center. Seven rolling robot design principles are presented and discussed （Sprung central member, Car driven, Mobile masses, Hemispherical wheels, Gyroscopic stabilisation, Ballast mass - fixed axis, and Ballast mass - moving axis）. Robots based on each of the design principles are shown and the performances of the robots are tabulated. An attempt is made to grade the design principles based on their suitability for movement over an unknown and varied but relatively smooth terrain. The result of this comparison suggests that a rolling robot based on a mobile masses principle would be best suited to this specific application. Some wonderful rolling organisms are introduced and defined as ＂active＂ or ＂passive＂ depending on whether they generate their own rolling motion or external forces cause their rolling.

关键词： Rolling robot tumbleweed wheel ballast Gryoscope

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Simulation and Visualisation of Functional Landscapes:Effects of the Water Resource Competition Between Plants

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Journal of Computer Science & Technology 2007年第6期22卷 835-845页

作者： vincent Le Chevalier Marc Jaeger 梅兴 Paul-Henry Cournède Ecole Centrale Paris Laboratory of Applied Mathematics and Systems Grande Voie des Vignes 92295 Chatenay-MalabryFrance INRIA Futurs DigiPlante TeamCIRAD AMAPTA A-51/PS2 34398 Montpellier Cedex 5France Sino-French Laboratory LIAMA Institute of AutomationChinese Academy of Sciences

Vegetation ecosystem simulation and visualisation are challenging topics involving multidisciplinary aspects. In this paper, we present a new generic frame for the simulation of natural phenomena through manageable and interacting models. It focuses on the functional growth of large vegetal ecosystems, showing coherence for scales ranging from the individual plant to communities and with a particular attention to the effects of water resource competition between plants. The proposed approach is based on a model of plant growth in interaction with the environmental conditions. These are deduced from the climatic data （light, temperature, rainfall） and a model of soil hydrological budget. A set of layers is used to store the water resources and to build the interfaces between the environmental data and landscape components： temperature, rain, light, altitude, lakes, plant positions, biomass, cycles, etc. At the plant level, the simulation is performed for each individual by a structural-functional growth model, interacting with the plant＇s environment. Temperature is spatialised, changing according to altitude, and thus locally controls plant growth speed. The competition for water is based on a soil hydrological model taking into account rainfalls, water runoff, absorption, diffusion, percolation in soil. So far, the incoming light radiation is not studied in detail and is supposed constant. However, competition for light between plants is directly taken into account in the plant growth model. In our implementation, we propose a simple architecture for such a simulator and a simulation scheme to synchronise the water resource updating （on a temporal basis） and the plant growth cycles （determined by the sum of daily temperatures）. The visualisation techniques are based on sets of layers, allowing both morphological and functional landscape views and providing interesting tools for ecosystem management. The implementation of the proposed frame leads to encouraging resu

关键词： landscape visualisation plant growth models natural phenomena simulation water cycle models

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The“Bitcoin Generator”Scam

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Blockchain(Research and Applications) 2022年第3期3卷 70-88页

作者： Emad Badawi Guy-vincent Jourdan Iosif-Viorel Onut Faculty of Engineering University of OttawaOttawaON K1N 6N5Canada IBM Centre for Advanced Studies OttawaON K1R 7Y6Canada

The“Bitcoin Generator Scam”(BGS)is a cyberattack in which scammers promise to provide victims with free cryptocurrencies in exchange for a small mining *** this paper,we present a data-driven system to detect,track,and analyze the *** works as follows:we first formulate search queries related to BGS and use search engines to find potential instances of the *** then use a crawler to access these pages and a classifier to differentiate actual scam instances from benign ***,we automatically monitor the BGS instances to extract the cryptocurrency addresses used in the scam.A unique feature of our system is that it proactively searches for and detects the scam ***,we can find addresses that have not yet received any *** data collection project spanned 16 months,from November 2019 to February *** uncovered more than 8,000 cryptocurrency addresses directly associated with the scam,hosted on over 1,000 ***,these addresses have received around 8.7 million USD,with an average of 49.24 USD per *** 70%of the active addresses that we are capturing are detected before they receive any transactions,that is,before anyone is *** also present some post-processing analysis of the dataset that we have captured to aggregate attacks that can be reasonably confidently linked to the same attacker or *** system is one of the first academic feeds to the APWG eCrime Exchange *** has been actively and automatically feeding the database since November 2020.

关键词： Cryptocurrency Scam analysis Cyberattack Fraud detection Bitcoin Blockchain analysis Data mining

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