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Characterization of the Generalized Calabi Composition of Affine Hyperspheres

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Acta Mathematica Sinica,English Series 2015年第10期31卷 1531-1554页

作者： Miroslava ANTI Ze Jun HU Ce Ce LI luc VRANCKEN University of Belgrade Faculty of Mathematics Studentski trg 16Pb.550 11000 Belgrade Serbia School of Mathematics and Statistics Zhengzhou University School of Mathematics and Statistics He'nan University of Science and Technology UVHC LAMAV F-59313 Valenciennes France and Katholieke Universiteit Leuven Departement WiskundeBE-3001 Leuven Belgium

In this paper, continuing with Hu-Li Vrancken and the recent work of Antid Dillen- Schoels-Vrancken, we obtain a decomposition theorem which settled the problem of how to determine whether a given locally strongly convex aitine hypersurface can be decomposed as a generalized Calabi composition of two affine hyperspheres, based on the properties of its difference tensor K and its affine shape operator S.

关键词： Generalized Calabi composition affine hyperspheres warped product

Genetic algorithm-based multiple moving target reaching using a fleet of sailboats

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IET Cyber-Systems and Robotics 2019年第3期1卷 93-100页

作者： Viel Christophe Vaultier Ulysse Wan Jian Jaulin luc School of Engineering Computing and MathematicsUniversity of PlymouthPlymouthDevonUK Lab STICC ENSTA BretagneBrestFrance

This study addresses the problem of Dynamic Travelling Salesman Problem for a multi-agent system using a fleet of sailboats.A genetic algorithm(GA)is proposed,which attributes to each agent a varying number of targets to be *** allows obtaining a suboptimal solution in the shortest time ***,this study adapts it to the specific problem involving a fleet of sailboats,which is a challenging task with comparison to autonomous underwater vehicles or motorised vehicles in terms of the *** motors can be flexibly controlled while sailboat movements are constrained by available wind direction and *** the method takes into account wind conditions at various locations of the *** results demonstrate the effectiveness of the proposed approach.

关键词： agent flex algorithm

Monotonic, cyclic and post-cyclic performances of single-helix anchor in residual soil of sandstone

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第4期11卷 824-836页

作者： Jose Antonio Schiavon Cristina de Hollanda Cavalcanti Tsuha luc Thorel Department of Geotechnical Engineering Aeronautics Institute of TechnologySao Jose dos CamposBrazil Department of Geotechnical Engineering University of Sao PauloSao CarlosBrazil IFSTTAR GERS DepartmentGeomaterials & Models in Geotechnics LaboratoryBouguenaisFrance

Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind *** most cases,these anchors are installed in tropical residual soil,a micro-structured material in which the shear strength is provided by soil *** installation of a helical anchor,as the helical plate moves downward into the ground,the soil penetrated is sheared and ***,in this type of soil,anchor installation affects the soil shear strength significantly associated with a bonded ***,the cyclic responses of helical anchors in this type of structured soils are rarely *** address this problem,tests were conducted in a Brazilian residual soil to investigate the monotonic,cyclic and post-cyclic performances of single-helix *** tests used two instrumented single-helix anchors installed in this typical residual soil of sandstone,which is frequently observed in large areas in the southern *** testing results indicate that the disturbance caused by the anchor installation affected the monotonic uplift performance *** results of cyclic loading tests also show no significant degradation of helix bearing resistance and reduced displacement accumulation with increasing load *** is perhaps due to the soil improvement caused by previous loading,which then increases the stiffness response of the anchor.

关键词： Helical anchors Tropical residual soil Cyclic loading Field load tests

Population structure and range expansion:the case of the invasive gastropod Cyclope neritea in northwest Iberian Peninsula

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Integrative Zoology 2012年第3期7卷 286-298页

作者： lucía COUCEIRO Lúa LÓPEZ JoséMiguel RUIZ Rodolfo BARREIRO Department of Ecology College of ScienceUniversity of A CoruñaA CoruñaSpain

Biotic invasions have a reputation for unpredictable ***,we report how slight changes in human activity responsible for the introduction and range expansion of a non-native mollusk have led to detectable differences in the genetics of the *** neritea is a non-predatory gastropod introduced to 2 areas of the European Atlantic:the northwest Iberian Peninsula(NWIP)and the French Atlantic coast(FAC).Shellfish seabed farming is intense in both areas but focuses on different commercial *** mitochondrial gene sequences,the lower genetic diversity recorded along the NWIP suggests a more homogeneous range of source populations than in the *** FAC,genetic diversity and haplotype composition in the NWIP correlate with the date of first occurrence of *** at each site rather than with geographical *** this pattern evokes the genetic signature expected under a serial-founder colonization model from a single initial enclave,a comparison with samples from potential source populations suggests that the NWIP probably experienced several independent *** jump dispersal pattern of *** in the NWIP,together with the observation that populations established in the same year are genetically undifferentiated,point to human transport as the most plausible explanation for the current range *** evidence for human-mediated dispersal,*** managed to develop a seemingly non-random genetic pattern in the *** is suggested that caution must be exerted when interpreting genetic patterns in invaders.

关键词： alien species Cyclope neritea cytochrome oxidase I genetic geographic pattern population structure

Numerical Schemes for Linear and Non-Linear Enhancement of DW-MRI

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Numerical Mathematics(Theory,Methods and Applications) 2013年第1期6卷 138-168页

作者： Eric Creusen Remco Duits Anna Vilanova luc Florack Department of Mathematics and Computer Science CASA Applied AnalysisEindhoven University of TechnologyP.O.Box 5135600 MBEindhovenThe Netherlands Department of Biomedical Engineering BMIA Biomedical Image AnalysisEindhoven University of TechnologyP.O.Box 5135600 MBEindhovenThe Netherlands

We consider the linear and non-linear enhancement of diffusion weighted magnetic resonance images(DW-MRI)to use contextual information in denoising and inferring fiber *** describe the space of DW-MRI images in a moving frame of reference,attached to fiber fragments which allows for convection-diffusion along the *** of this approach,our method is naturally able to handle crossings in *** will perform experiments showing the ability of the enhancement to infer information about crossing structures,even in diffusion tensor images(DTI)which are incapable of representing crossings *** will present a novel non-linear enhancement technique which performs better than linear methods in areas around ventricles,thereby eliminating the need for additional preprocessing steps to segment out the *** pay special attention to the details of implementation of the various numeric schemes.

关键词： DTI DW-MRI scale spaces finite differences convection-diffusion adaptive diffusion Perona-Malik diffusion Lie groups

Phase control of ellipsometric interferometer for nanometric positioning system

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Science China(Technological Sciences) 2011年第12期54卷 3424-3430页

作者： XU SuAn CHASSAGNE luc TOPCU Suat ZHONG ShaoJun HUANG YanYan College of Mechanical and Electrical Engineering China Jiliang University Hangzhou 310018 China LISV University of Versailles Saint-Quentin Versailles cedex 78035 France

Development in industry is asking for improved resolution and higher accuracy in dimensional metrology. In this paper,we proposed a control displacement method based on a polarization ellipsometirc interferometer and phase-locked loop technique. The proposed principle was set up. The experimental results of step and step displacements with a step value of 5 nm were presented. We also analyzed the resolution,the potential minimal displacement of the established system. The results show that the position error induced by the ellipticty deviation of the light beam becomes negligible thanks to our signal processing circuit with high-order filter. This method could be useful for many applications in nano dimensional metrology and semiconductor industry.

关键词： ellipsometric interferometer phase locked loop nanometric position control displacement monitoring

Redistribution and magnitude of stresses around horse shoe and circular excavations opened in anisotropic rock

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International Journal of Mining Science and Technology 2015年第4期25卷 615-621页

作者： Mambou Ngueyep luc Leroy Ndop Joseph Ndjaka Jean-Marie Bienvenu Laboratory of Material Sciences Department of Physics Faculty of Sciences University of Yaoundé 1 Department of Mine Mineral Processing and Environment School of Geology and Mining Engineering University of Ngaoundéré Douala Institute of Technology

In this paper numerical analysis of underground structures, taking account the transverse isotropy system of rocks, was done using CAST 3M code by varying the shape of excavation and the coefficient of earth pressure k. Numerical results reveal that the anisotropy behavior, the shape of hole and the coefficient of earth pressure k have significant influence to the mining induced stress field and rock deformations which directly control the stability of underground excavation design. The magnitude of horizontal stress obtained for the horse shoe shape excavation(25.2 MPa for k = 1; 52.7 MPa for k = 2)is lower than the magnitude obtained for circular hole(26.4 MPa for k = 1; 59.5 MPa for k = 2).Therefore, we have concluded that the horse shoe shape offers the best stability and the best design for engineer. The anisotropy system presented by rock mass can also influence the redistribution of stresses around hole opened. Numerical results have revealed that the magnitude of redistribution of horizontal stresses obtained for transverse isotropic rock(12.1 MPa for k = 0.5; 25.2 MPa for k = 1 and52.7 MPa for k = 2) is less than those obtained in the case of isotropic rock(27.6 MPa for k = 1;48.6 MPa for k = 2 and 90.81 MPa for k = 2). The more the rock has the anisotropic behavior, the more the mass of rock around the tunnel is stable.

关键词： Horse shoe excavation Stress Strain Transverse isotropy Finite element

Offering Adequate Pedagogical Progression via Mobile Equipments——Experiment of a French Engineering School

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开放教育研究 2006年第1期12卷 59-62页

作者： Jean-luc Koning Grenoble National Institute of Technology France

Students may enter our 5-year engineering school in France at two levels; first and third year. However, due to their quite different backgrounds (this is especially true for third year students) , we need to provide newcomers with a 6-week training period during which they follow classes in the fields where they particularly feel weak. Unfortunately, depending on the student' s background, this is not always possible to bring him/her to the expected level. Another aspect one needs to mention is that these students may not have the same weaknesses in a given field. However, for economical reasons, those classes follow a uniform program as it is not feasible to provide a customised progression. In this paper we discuss how to redesign a mathematics course so as to offer tailored exercise sequencing. Groups of 20 students could then draw their exercises from an intranet database according to their previously completed work, try to solve it by themselves, request additional hints and even ask for some direct help from the teacher. Such a database is currently under development. If it turns out several students stumble against the same difficulty the teacher could show the whole class room how to solve it using the digital projector. This project goes one step further than our initial mobile education project (2003 - 2004 ). Until recently, we had used the equipment in a unique direction, from the instructor toward the students. Here, in this new project we are focusing on the whole loop in order to offer a more adequate (personalized) pedagogical progression ; from the student to the teacher (when the tablet PCs are monitored by the teacher) , and back toward the students (when a direct help is provided by the teacher).

关键词：法国移动学习设备工程院校开放教育教学方法

Mass Screening Using Antigenic and Molecular Diagnostic Tests of COVID-19 in Bangui at the Beginning of the Second Wave in July 2021

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Journal of Tuberculosis Research 2024年第1期12卷 1-12页

作者： Clotaire Donatien Rafaï Marie-Roseline Darnycka Belizaire Pierre Somse Wilfrid Sylvain Nambei Ernest Lango-Yaya Oscar Senzongo luc Salva Hereidebona Ulrich Jeffrey Kotemossoua Rabbi Mermoz Senekian Simon Pounguinza Christian-Diamant Mossoro-Kpinde Alain Le Faou Jean De Dieu Longo François-Xavier Mbopi-Keou Gérard Grésenguet Boniface Koffi National Laboratory of Clinical Biology and Public Health Bangui Central African Republic Faculty of Health Sciences University of Bangui Bangui Central African Republic World Health Organization Bangui Central African Republic Ministry of Health and Population Bangui Central African Republic Faculty of Medicine Maieutic and Health Sciences University of Lorraine Pole Brabois Santé Nancy France Faculty of Medicine and Biomedical Sciences University of Yaounde I Yaounde Cameroun

Objective: COVID-19 surveillance was established as early as March 2020 in the Central African Republic (CAR), after the WHO statement relating to the identification of several cases outside China. However, given the non-performing molecular biology technical platform in many developing countries in sub-Saharan Africa, the second wave promised to be surprising and formidable. In this context, a mass survey was launched in Bangui to determine the prevalence of COVID-19. Patients and Methods: From March 18 to April 2, 2021, a mass screening campaign took place in tourist places, companies and the main hospital infrastructures. Nasopharyngeal swab samples were collected from participants with and without symptoms of Influenza-like illness (ILI) and stored in VTM tubes. The Ag (COVID-19) and RT-PCR tests were carried out in Bangui at the LNBCSP. The sequencing of RT-PCR SARS-CoV-2 positives was carried out at the INRB. Results: We included 1480 participants of whom 33 (2.23%) were SARS-COV-2 positive, of whom 24 were male and 9 female. This sex difference was statistically significant (p = 0.012) as the sex ratio M/F was 1.09. Sampling sites located in the 1st arrondissement were the most prolific (p = 0.006) and were sequenced. In addition to the analysis of the 33 samples from the predefined sites under study, 17 control sequences from the provinces generated during the same period are added. We detected 2 Variants Of Concern (VOC) including the predominant B.1.620 (43.86%) followed by B.1.1.7 or Alpha (5.10%). Conclusion: The study showed the importance of surveillance and the availability of means of diagnosis of COVID-19. The identified risk factors were sex and sampling site. This study has shown the importance of setting up sentinel sites for COVID-19 surveillance in all regions of the country and the appropriate use of the anti-COVID-19 vaccine.

关键词： COVID-19 Variants Central African Republic