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Stability analysis of the fluttering and autorotation of flow-induced rotation of a hinged flat plate

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Journal of Hydrodynamics 2013年第5期25卷 755-762页

作者： MIRZAEISEFAT Sina FERNANDES antonio carlos Department of Naval Architecture and Marine Engineering University of Michigan COPPE/UFRJ Federal University of Rio de Janeiro

This work describes investigations performed on the interaction of uniform current and freely rotating plate about a fixed vertical axis. Fluttering and autorotation are two different motions that may occur during the flow induced rotation. The dimensional analysis proves that the motion in flow induced rotation motion is governed essentially by the dimensionless moment of inertia and Reynolds number. Certain combinations define the stability boundaries between fluttering and autorotation. Fluttering is oscillation of body about a vertical axis and the autorotation is a name given to the case when the body turns continuously about the vertical axis First, the loads and moment coefficients are calculated by experiments and streamline theory for different angles of attack for a fixed fiat plate. Then for dynamic case, a bifurcation diagram is presented based on experiments to classify different motion states of flow induced rotation. Finally, a dynamical model is proposed for stability analysis of flow induced rotation of a flat plate.

关键词： flow-induced rotation autorotation fluttering stability analysis

Phenomenological model for torsional galloping of an elastic flat plate due to hydrodynamic loads

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Journal of Hydrodynamics 2014年第1期26卷 57-65页

作者： FERNANDES antonio carlos ARMANDEI Mohammadmehdi Department of Naval and Ocean Engineering COPPE/UFRJ

This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rectangular flat plate with an elastic axis in its mid-chord length. The elasticity is provided by torsion spring. The flat plate has only one degree of freedom which is rotation in pure yaw about its axis. It is observed that as the current speed is higher than a critical velocity, the flat plate becomes unstable. The instability leads to torsional galloping occurrence, as a result of which the flat plate begins to yaw about the elastic axis. By testing two different chord lengths each with several torsion spring rates, the flat plate behavior is investigated and three different responses are recognized. Then, a phenomenological model is developed with the original kernel in the form of the van der Pol-Duffing equa-tion. The model explains these three responses observed experimentally.

关键词： torsional galloping flow-induced oscillation phenomenological model van der Pol-Duffing equation

Impact of radiative cooling on the energy performance of courtyards in Mediterranean climate

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Building Simulation 2024年第9期17卷 1491-1513页

作者： carlos-antonio Domínguez-Torres antonio Domínguez-Delgado Escuela Técnica Superior de Arquitectura Universidad de SevillaAv.de Reina Mercedes241012 SevillaSpain Department of Applied Mathematics 1 Escuela Técnica Superior de ArquitecturaUniversidad de SevillaAv.de Reina Mercedes241012 SevillaSpain

Radiative cooling has proven to be a useful tool to address the problems of lack of comfort and excessive energy consumption in situations of high temperatures,overheating and heat ***,incorporating courtyards in warm climate zones has been found to be highly beneficial in addressing similar ***,there is interest in analyzing the combined effects of both:radiative cooling and *** paper presents an analysis of the impact of the application of radiative cooling on a courtyard using a comprehensive simulation approach that includes a CFD model for the thermodynamic airflow in the adjacent roofs and inside the courtyard,equations for the transient heat conduction through roofs,walls and courtyard slabs,and a hybrid raytracing-radiosity model for the evaluation of the solar radiation reaching the building surfaces and its reflections,both of specular and diffuse origin,and for the calculation of the thermal radiation exchange,especially with the *** results show that in the hot season,the courtyard with radiative cooling always provides lower temperatures than the initial courtyard does,with a temperature range of 18.33℃to 33.78℃,compared to a range of 19.32℃to 38.00℃in the initial courtyard,and producing a greater difference with outdoor temperatures that can reach 12℃versus 8℃for the reference *** addition,it was found that the courtyard with radiative cooling is able to significantly reduce the observed nighttime overheating by providing lower temperatures than the outdoor temperatures in the 50%of the nights *** was also found that the thermal loads to achieve indoor thermal comfort in the spaces adjacent to the courtyard were reduced by 63.46%to 69.85%.

关键词： radiative cooling passive cooling CFD three-dimensional modeling energy saving thermal comfort

Optimal heat release shaping in a reactivity controlled compression ignition （RCCI） engine

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Control Theory and Technology 2017年第2期15卷 117-128页

作者： carlos GUARDIOLA Benjamin PLA antonio GARCiA Vicente BORONAT CMT-Motores Termicos Universitat Politecnica de Valencia Valencia Spain

The present paper addresses the optimal heat release （HR） law in a single cylinder engine operated under reactivity controlled compression ignition （RCCl） combustion mode to minimise the indicated specific fuel consumption （ISFC） subject to different constraints including pressure related limits （maximum cylinder pressure and maximum cylinder pressure gradient）. With this aim, a 0-dimensional （OD） engine combustion model has been identified with experimental data. Then, the optimal control problem of minimising the ISFC of the engine at different operating conditions of the engine operating map has been stated and analytically solved. To evaluate the method viability a data-driven model is developed to obtain the control actions （gasoline fraction） leading to the calculated optimal HR, more precisely to the optimal ratio between premixed and diffusive combustion. The experimental results obtained with such controls and the differences with the optimal HR are finally explained and discussed.

关键词： Diesel engine RCCI combustion analysis optimal control

COMPLEX SYSTEMS IN SPORTS:INTRODUCTION TO THE SPECIAL ISSUE

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Journal of Systems Science & Complexity 2013年第1期26卷 1-3页

作者： MERELO Juan Julin MORA antonio M COTTA carlos Depto.ATC CITICUniversidad de Granada Depto.LCC Universidad de Malaga

1 Complex Systems in Sports Sport is one of the most important activities of *** relevance goes beyond the physical/psychological benefits that their practicing provides(an aspect that justifies in itself its importance in our current society).In fact,be it as actually playing some sport or just watching some games,it provides a huge means for socialization and *** to say,the economical viewpoint is also enormously relevant:events such as the Olympic Games。

关键词：复杂系统运动教育手段社会化

A Finite Element Study of the Influence of Graphite Nodule Characteristics on a Subsurface Crack in a Ductile Cast Iron Matrix under a Contact Load

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Computer Modeling in Engineering & Sciences 2018年第10期117卷 59-71页

作者： Guilherme Suguinoshita carlos Henrique da Silva Marco antonio Luersen Department of Mechanical Engineering Federal University of Technology-Parana(UTFPR)Rua Deputado Heitor Alencar Furtado5000CEP 81280-340CuritibaBrazil

This paper describes a study of the effects of graphite nodule characteristics on a subsurface crack in austempered ductile iron(ADI).A representative specimen of ADI,subjected to sliding contact load,is modeled using finite elements aiming to obtain the shear stress intensity factor(KII).The parameters varied were(i)the nodule diameter(two different values were considered),(ii)the distance between the nodule and the tip of the crack and(iii)the position of the load relative to the tip of the *** results of the numerical simulations show that the smaller diameter nodule has a larger influence on KII,suggesting a higher contact fatigue crack propagation rate in the material with the smaller *** results are the opposite of those observed in experimental studies and would appear to indicate that other factors should be also considered to ensure realistic estimates of the contact fatigue strength of ADI.

关键词： Austempered ductile iron subsurface crack stress intensity factor finite element analysis graphite nodule

Probing the nature of the contact between fine particles by using ultrasound propagation

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Particuology 2011年第6期9卷 659-662页

作者： antonio Castellanos Xiaoping Jia carlos Soria-Hoyo Jose Manuel Valverde Faculty of Physics University of Seville Avda. Reina Mercedes s/n 41012 Seville Spain LPMDI Universite de Marne-la-Vallee CNRS UMR 8108 Champs sur Marne France

The propagation velocity （Vs） of an ultrasonic signal through a granular material depends on the type of interparticle contact. For noncohesive glass beads, a power law behavior Vs α σc1/6 for consolidation stresses applied （σc） above 1 MPa has been measured in previous work. This equation is compatible with Hertz＇s interaction law between elastic solids. In the present work, we have tested the propagation velocity of ultrasound signals through a sample of fine powder. The tensile strength and compactivity of the powder were previously measured by means of the Seville powder tester （SPT）, indicating plastic deformation of the surface asperities in contact for small to moderate consolidation stresses. However, the measurements of ultrasound propagation at high consolidations presented here are compatible with Hertz＇s law. This finding suggests that for high consolidation stresses, surface asperities are flattened, and it is therefore the elastic deformation of the bulk of the particles that determines the transmission of ultrasonic pulses.

关键词： JFine cohesive powder Ultrasound propagation Interparticle contact

A NETWORK ANALYSIS OF THE 2010 FIFA WORLD CUP CHAMPION TEAM PLAY

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Journal of Systems Science & Complexity 2013年第1期26卷 21-42页

作者： COTTA carlos MORA antonio M MERELO Juan Julin MERELO-MOLINA Cecilia Department of Computer Science University of Mlaga Department of Architecture and Computer Technology University of Granada

This paper analyzes the network of passes among the players of the Spanish team during the last FIFA World Cup 2010,where they emerged as the champion,with the objective of explaining the results obtained from the behavior at the complex network *** team is considered a network with players as nodes and passes as(directed) edges.A temporal analysis of the resulting passes network is also done,looking at the number of passes,length of the chain of passes,and to network measures such as player centrality and clustering *** of the last three matches(the decisive ones) indicate that the clustering coefficient of the pass network remains high,indicating the elaborate style of the Spanish *** effectiveness of the opposing team in negating the Spanish game is reflected in the change of several network measures over time,most importantly in drops of the clustering coefficient and passing length/speed,as well as in their being able in removing the most talented players from the central positions of the ***'s ability to restore their combinative game and move the focus of the game to offensive positions and talented players is shown to tilt the balance in favor of the Spanish team.

关键词： Complex network complex systems FIFA World Cup football La Roja network analysis soccer Spanish team sports.

Nanostructural Evolution of Sugarcane Rind and Pith Submitted to Hydrothermal Pretreatments

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Journal of Renewable Materials 2018年第2期6卷 152-159页

作者： Marcelo M.Oliveira antonio A.S.Curvelo carlos Driemeier Brazilian Bioethanol Science and Technology Laboratory(CTBE) Brazilian Center for Research in Energy and Materials(CNPEM)Caixa Postal 619213083-970CampinasSão PauloBrasil São carlos School of Engineering(EESC) University of São Paulo(USP)Caixa Postal 78013560-970São CarlosSão PauloBrasil São carlos Institute of Chemistry(IQSC) University of São Paulo(USP)Caixa Postal 78013560-970São CarlosSão PauloBrasil

Lignocellulose conversion into cellulosic ethanol and coproducts starts with a pretreatment *** current industrial plants of cellulosic ethanol use thermochemical pretreatments under hydrothermal conditions,with or without addition of acid *** pretreatments modify biomass chemistry and morphology,particularly at the *** this work,we use X-ray diffraction,dynamic vapor sorption and calorimetric thermoporometry to investigate the biomass nanostructural changes promoted by hydrothermal *** compare and differentiate the rind and pith fractions of sugarcane stalks in order to contribute to the understanding of rind-pith contrasting ***,for both cane fractions our results point consistently to cellulose co-crystallization,lignin aggregation,and opening of nanoscale pores as the main nanostructural phenomena occurring during hydrothermal treatments.

关键词： Cellulose bagasse sugarcane cellulosic ethanol pretreatment