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Enhancement of the benthic communities around an isolated island in the Antarctic Ocean

Acta Oceanologica Sinica 2013年第6期32卷 47-55页

作者： José I Saiz Nuria Anadón Javier Cristobo oscar garcía-alvarez Gerardo garcía-Castrillo Eduardo López Cruz Palacín Jesús S Troncoso Ana Ramos Department of Zoology and Animal Cell Biology University of the Basque CountryBilbao 48080 Spain Department of Organisms and Systems Biology (Zoology) Rodrigo Uría s/n University of OviedoOviedo 33071 Spain Spanish Institute of Oceanography Gijón Oceanographic Centre Príncipe de Asturias 70bisGijón 33212 Spain Department of Zoology and Physical Anthropology University of Santiago de CompostelaSouth Campus Santiago de Compostela 15706 Spain Cantabrian Maritime Museum San Martín de Bajamar s/nSantander 39004 Spain Department of Biology Faculty of Sciences Autonomous University of MadridMadrid 28049 Spain Department of Animal Biology University of BarcelonaAvinguda Diagonal 645 Barcelona 08028 Spain Department of Ecology and Animal Biology Marine Sciences Faculty University of VigoVigo 36310 Spain Spanish Institute of Oceanography Subida a Radio Faro 50-52Vigo 36390 Spain

Insular marine biotas are often richer in faunal diversity than those from the open sea in the same geo- graphical region. The existence of particular island effects were tested under polar conditions by compar- ing infaunal benthic assemblages on Peter I Island with those of similar latitudes in the open ocean at the Bellingshausen Sea and also from the coast of the Antarctic Peninsula. Sampling was carried out aboard the R/V Hesperides during the expedition named BENTART-2003 from 24 January to 3 March 2003. Benthic samples were collected at 18 stations ranging from 90 to 2 044 m depth, using an USNEL-type box corer （BC） dredge. Representatives of 32 higher taxa of invertebrates were found. Univariate and multivariate analyses revealed various patterns in the data. First, significant differences in polychaete abundance were detected between the stations located in the open sea and the remaining sites （island plus mainland sites）. Bivalve abundances were also distinct between island and mainland sampling sites. Sediment columns taken from the island seafloor exhibited the highest rate of bioturbation by the infauna. These findings confirm the model that islands develop distinct assemblages characterized by the enhancement of the benthic commu- nities even in cold waters. Several abiotic factors were measured simultaneously at the seafloor and along the water column to investigate faunal distribution patterns. Significant correlations were found between the benthic assemblages and a combination of two environmental variables：＂island effect＂（measured as a categorical variable） and the redox state of sediments. Richer and more complex benthic assemblages were found in Peter I Island＇s sea bottom, whereas the more depauperate bottoms remained in the open sea.

关键词： Antarctica Bellingshausen Sea benthos Peter I Island PRIMER

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Correlation analysis among vorticity,Q method and Liutex

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Journal of Hydrodynamics 2020年第6期32卷 1207-1211页

作者： Yifei Yu Pushpa Shrestha oscar alvarez Charles Nottage Chaoqun Liu Department of Mathematics the University of Texas at ArlingtonArlington76019USA

Influenced by the fact that vorticity represents rotation for rigid body,people believe this idea also works for fluid ***,the vortex predictions by vorticity do not match experimental results,which drove scientists to look for more appropriate methods to identify *** vortex identification methods can be categorized into three *** vorticity-based method is classified as the first *** relying on eigenvalues of velocity gradient tensor are considered as the second *** still believe vorticity is vortex since vorticity theory looks correct in mathematics,but all other methods are only scalars and unable to indicate the swirl ***,a new vortex identification method called Liutex is *** is regarded as the third-generation method,not only overcoming all previous methods’drawbacks but also having a clear physical *** direction of Liutex represents the swirl axis of rotation,and its strength is equal to twice the angular *** this paper,we did a correlation analysis between vorticity,Q,λ_(ci),λ_(2)methods and Liutex based on a direct numerical simulation(DNS)case of boundary layer *** results show that the correlation between vorticity and Liutex is very small or even negative in strong shear regions,which demonstrates that using vorticity to detect vortex lacks scientific foundation and vorticity is not appropriate to represent *** correlation analysis also shows that the second generation is contaminated too by shear and thus is not accurate to identify the vortex structure.

关键词： Correlation Liutex vorticity Q method λ_(ci)method λ_(2)method

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Superplasticity of a friction stir processed overaged WE54 magnesium alloy

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Journal of Magnesium and Alloys 2022年第11期10卷 3156-3166页

作者： oscar A.Ruano Marta alvarez-Leal Alberto Orozco-Caballero Fernando Carreño Physical Metallurgy Department CENIM-CSICAv.Gregorio del Amo 828040 MadridSpain Department of R&D and programmes Technology Centre of Metal-Mechanical and Transport(CETEMET).Avda.1°de Mayos/n.LinaresJaén2370Spain Department of Mechanical Engineering Chemistry and Industrial DesignPolytechnic University of MadridRonda de Valencia 328012MadridSpain

The coarse-grained WE54 magnesium alloy was heat treated in order to have minimum hardness minimizing the effects of precipitates and solid solution. Friction stir processing(FSP) was applied in severe conditions to obtain fine, equiaxed and highly misoriented grains, with grain sizes even less than 1 μm. The high severity of processing demonstrated to have a strong impact in the microstructure. Consequently,the processed materials exhibited excellent superplasticity at the high strain rate 10^(-2)s^(-1), and temperatures between 300 and 400 ℃. The maximum tensile superplastic elongation of 756% was achieved at 400 ℃ thanks to the operation of grain boundary sliding mechanism(GBS). Besides the new data obtained through tensile testing, the paper deals with a transcendental question regarding the large differences in strain rate values at a given stress in the superplastic regime at maximum elongation compared to other magnesium-based alloys. With this is mind, 19 magnesium alloys from 22 different investigations were analyzed to give some light to this behavior that never was treated before. It is proposed that this behavior has to be attributed to the accommodation process, necessary for GBS to occur, which is hindered by reinforcing solutes.

关键词： WE54 magnesium alloy Friction stir processing Processing severity Superplasticity Grain boundary sliding Solutes

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Rolling Bearing Condition Monitoring Technique Based on Cage Rotation Analysis and Acoustic Emission

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Journal of Dynamics, Monitoring and Diagnostics 2022年第2期1卷 57-65页

作者： Matías Marticorena oscar garcía Peyrano Vibrations Laboratory Vibrations DivisionNational Atomic Energy CommissionSan Carlos de BarilocheArgentina Balseiro Institute Cuyo National UniversitySan Carlos de BarilocheArgentina

In this paper,we present an alternative technique for detecting changes in the operating conditions of rolling element bearings(REBs)that can lead to premature *** developed technique is based on measuring the kinematics of the bearing *** rotational motion of the cage is driven by traction forces generated in the contacts of the rolling elements with the *** is known that the cage angular frequency relative to shaft angular frequency depends on the bearing load,the bearing speed,and the lubrication condition since these factors determine the lubricant film thickness and the associated traction *** a large percentage of REB failures are due to misalignment or lubrication problems,any evidence of these conditions should be interpreted as an incipient *** this paper,a novel method for the measurement of the instantaneous angular speed(IAS)of the cage is *** method is evaluated in a deep groove ball bearing test rig equipped with a cage IAS sensor,as well as a custom acoustic emission(AE)transducer and a piezoelectric *** IAS of the cage is analyzed under different bearing loads and shaft speeds,showing the dependence of the cage angular speed with the calculated lubricant film *** bearing faulty operating conditions(mixed lubrication regime,lubricant depletion,and misalignment)are *** is shown that the cage IAS is dependent on the lubrication regime and is sensitive to *** AE signal is also used to evaluate the lubrication *** results suggest that the proposed technique can be used as a condition monitoring tool in industrial environments to detect abnormal REB conditions that may lead to premature failure.

关键词： acoustic emission cage instantaneous angular speed condition monitoring cyclostationary analysis rolling element bearing

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Stretching and shearing contamination analysis for Liutex and other vortex identification methods

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Advances in Aerodynamics 2021年第1期3卷 166-185页

作者： Pushpa Shrestha Charles Nottage Yifei Yu oscar alvarez Chaoqun Liu Department of Mathematics The University of Texas at ArlingtonArlingtonTX 76019USA

The newly developed vortex-identification method,Liutex,has provided a new systematic description of the local fluid rotation,which includes scalar,vector,and tensor ***,the advantages of Liutex over the other widely used vortexidentification methods such as Q,Δ,λ2,andλci have not been *** traditional methods count on shearing and stretching as a part of vortex ***,in the real flow,shearing and stretching do not contribute to fluid *** this paper,the decomposition of the velocity gradient tensor is conducted in the Principal Coordinate for *** the contamination effects of stretching and shearing of the traditional methods are investigated and compared with the Liutex method in terms of mathematical analysis and numerical *** results show that the Liutex method is the only method that is not affected by either stretching or shear,as it represents only the local fluid rigid *** results provide supporting evidence that Liutex is the superior method over others.

关键词： Liutex Vorticity Vortex Omega method Transition flow Velocity gradient tensor Principal coordinate Principal tensor Liutex tensor decomposition

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Comparative mitogenome phylogeography of two anteater genera (Tamandua and Myrmecophaga;Myrmecophagidae, Xenarthra): Evidence of discrepant evolutionary traits

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Zoological Research 2021年第5期42卷 525-547页

作者： Manuel Ruiz-garcía Daniel Pinilla-Beltrán oscar E.Murillo-garcía Christian Miguel Pinto Jorge Brito Joseph Mark Shostell Laboratorio de Genética de Poblaciones Molecular-Biología Evolutiva Departamento de BiologíaFacultad de CienciasPontificia Universidad JaverianaBogotáDC 110231Colombia Grupo de Investigación en Ecología Animal Departamento de BiologíaFacultad de Ciencias Naturales y ExactasUniversidad del ValleApartado AéreoCali 25360Colombia Instituto de Ciencias Biológicas Escuela Politécnica NacionalQuito 17012759Ecuador Instituto Nacional de Biodiversidad(INABIO) Quito 170135Ecuador Math Science and Technology DepartmentUniversity of Minnesota CrookstonCrookstonMN 56716USA

The species within Xenarthra(sloths,anteaters,and armadillos)are quintessential South American *** the three groups,Vermilingua(anteaters)contains the fewest extant and paleontological ***,we sampled and sequenced the entire mitochondrial genomes(mitogenomes)of two Tamandua species(Tamandua tetradactyla and ***)(n=74)from Central and South America,as well as Myrmecophaga tridactyla(n=41)from South *** Tamandua,we detected three different *** oldest(THI)contained many specimens with the *** morphotype(but also several with the *** morphotype)and originated in southeastern South America(currently Uruguay)before moving towards northern South America,where the THII haplogroup *** primarily contained specimens with the *** morphotype(but also several with the *** morphotype)and was distributed in Central America,Colombia,and *** and THII yielded a genetic distance of 4%.THII originated in either northern South America or“in situ”in Central America with haplogroup THIII,which consisted of~50%*** and 50%*** *** was mostly located in the same areas as THII,i.e.,Central America,Ecuador,and Colombia,though mainly in the *** three haplogroups overlapped in Colombia and ***,*** and *** were not reciprocally *** this reason,we considered that a unique species of Tamandua likely exists,i.e.,*** contrast to Tamandua,*** did not show different morphotypes throughout its geographical range in the ***,two very divergent genetic haplogroups(MHI and MHII),with a genetic distance of~10%,were *** basal haplogroup,MHI,originated in northwestern South America,whereas the more geographically derived haplogroup,MHII,overlapped with MHI,but also expanded into central and southern South ***,Tamandua migrated from south to north whereas Myrmecophaga migrated from

关键词： Anteaters Genetic diversity Mitogenomes Myrmecophaga Neotropics Phylogeography Spatial structure Tamandua

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Online Unbalance Detection and Diagnosis on Large Flexible Rotors by SVR and ANN trained by Dynamic Multibody Simulations

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Journal of Dynamics, Monitoring and Diagnostics 2022年第3期1卷 139-147页

作者： oscar garcía Peyrano Juan Vignolo Rodrigo Mayer Matías Marticorena Balseiro Institute Cuyo National UniversitySan Carlos de BarilocheArgentina GPSignal San Carlos de BarilocheArgentina Vibrations Laboratory Vibration DivisionNational Atomic Energy CommissionSan Carlos de BarilocheArgentina

Multiple-stage steam turbine generators,like those found in nuclear power plants,pose special challenges with regards to mechanical unbalance *** factors contribute to a complex vibrational response,which can lead to incorrect assessments if traditional condition monitoring strategies are used without considering the mechanical system as a ***,in turn,can lead to prolonged machinery *** machine learning techniques can be used to integrally correlate mechanical unbalance along the shaft with transducer signals from rotor ***,this type of machinery has scarce data regarding faulty ***,a variety of fault conditions can be simulated in order to generate these data using computational models to simulate the dynamic response of individual *** the present work,a multibody model of a 640MWsteam turbine flexible rotor is employed to simulate mechanical unbalance in several positions along the *** components of the resulting vibration signals at each bearing are obtained and utilized as training data for two regression models designed for mechanical unbalance *** first approach uses an artificial neural network and the second one utilizes a support vector regression *** order to test their performance,the stiffness of each bearing in the multibody simulation was altered between 50%and 150%of the training model values,random noise was added to the signal and several dynamic unbalance conditions were *** show that both approaches can reliably diagnose dynamic rotor unbalance even when there is a typical degree of uncertainty in bearing stiffness values.

关键词： condition monitoring mechanical unbalance machine learning steam turbine

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Developing a dynamic growth model for teak plantations in India

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Forestry Studies in China 2014年第2期16卷 71-80页

作者： Vindhya Prasad Tewari Juan Gabriel lvarez-gonzález oscar garcía Forest Biometry Division Institute of Wood Science and TechnologyBangaloreIndia Unidad de Gestión Forestal Sostenible Departamento de Ingenieria AgroforestalUniversidad de Santiago de CompostelaLugoSpain University of Northern British Columbia ColumbiaBCCanada

Background： Tectono grandis （teak） is one of the most important tropical timber species occurring naturally in India. Appropriate growth models, based on advanced modeling techniques, are not available but are necessary for the successful management of teak stands in the country. Long-term forest planning requires mathematical models and the principles of Dynamical System Theory provide a solid foundation for these. Methods： The state-space approach makes it possible to accommodate disturbances and avarying environment. In this paper, an attempt has been made to develop a dynamic growth model based on the limited data, consisting of three annual measurements, collected from 22 teak sample plots in Karnataka, Southern India. Results： A biologically consistent whole-stand growth model has been presented which uses the state-space approach for modelling rates of change of three state-variables viz., dominant height, stems per hectare and stand basal area. Moreover, the model includes a stand volume equation as an output function to estimate this variable at any point in time. Transition functions were fitted separately and simultaneously. Moreover, a continuous autoregressive error structure is also included in the modelling process. For fitting volume equation, generalized method of moments was used to get efficient parameter estimates under heteroscedastic conditions. Conclusions： A simple model containing few free parameters performed well and is particularly well suited to situations where available data is scarce.

关键词： Mortality Basal area Canopy closure Relative occupancy State-space approach Tectona grandis

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An Architecture for Software Engineering Gamification

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Tsinghua Science and Technology 2020年第6期25卷 776-797页

作者： oscar Pedreira Felix garcia Mario Piattini Alejandro Cortinas Ana Cerdeira-Pena the Universidade da Coruna Centro de Investigacion CITICLaboratorio de Bases de DatosFacultade de InformaticaElvinaA Coruna15071Spain the Universidad de Castilla-La Mancha Grupo AlarcosEscuela Superior de InformaticaPaseo de la Universidad4Ciudad Real13071Spain.

Gamification has been applied in software engineering to improve quality and results by increasing people’s motivation and engagement.A systematic mapping has identified research gaps in the field,one of them being the difficulty of creating an integrated gamified environment comprising all the tools of an organization,since most existing gamified tools are custom developments or *** this paper,we propose a gamification software architecture that allows us to transform the work environment of a software organization into an integrated gamified environment,i.e.,the organization can maintain its tools,and the rewards obtained by the users for their actions in different tools will mount *** developed a gamification engine based on our proposal,and we carried out a case study in which we applied it in a real software development *** case study shows that the gamification engine has allowed the company to create a gamified workplace by integrating custom-developed tools and off-the-shelf tools such as Redmine,TestLink,or JUnit,with the gamification *** main advantages can be highlighted:(i)our solution allows the organization to maintain its current tools,and(ii)the rewards for actions in any tool accumulate in a centralized gamified environment.

关键词： gamification software engineering gamification architecture gamification engine

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Rolling Bearing Remaining Useful Life Prediction Based on Wiener Process

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Journal of Dynamics, Monitoring and Diagnostics 2022年第4期1卷 229-236页

作者： Wentao Zhao Chao Zhang Shuai Wang Da Lv oscar garcía Peyrano School of Mechanical Engineering Inner Mongolia University of Science and TechnologyBaotou 014010China Inner Mongolia Key Laboratory of Intelligent Diagnosis and Control of Mechatronic System Baotou 014010China Cuyo University San Carlos de BarilocheArgentina

Rolling bearing is the key part of mechanical *** prediction of bearing life can reduce maintenance costs,improve availability,and prevent catastrophic consequences,aiming at solving the problem of the nonlinear,random and small sample problems faced by rolling bearings in actual operating *** this work,the nonlinearWiener process with random effect and unbiased estimation of unknown parameters is used to predict the remaining useful life of rolling ***,random effects and nonlinear parameters are added to the traditional Wiener process,and a parameter unbiased estimation method is used to estimate the positional parameters of the constructed Wiener ***,the model is validated using a common set of bearing *** results show that compared with the traditional maximum likelihood function estimation method,the parameter unbiased estimation method can effectively improve the accuracy and stability of the parameter estimation *** model has a good fitting effect,which can accurately predict the remaining useful life of rolling bearing.

关键词： parameter estimation remaining useful life rolling bearing Wiener process

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