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Three Problems on Trigonometric Sums

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Acta Mathematica Sinica,English Series 2019年第6期35卷 721-727页

作者： Yves meyer CMLA ENS Paris-Saclay

Let Λ ? R^n be a uniformly discrete set and let C_Λ be the vector space consisting of all mean periodic functions whose spectrum is simple and contained in Λ. If Λ is a gentle set then for every f ∈ C_Λ we have f(x) = O(ω_Λ(x)) as |x| →∞ and ω_Λ(x) can be estimated(Theorem 4.1). This line of research was proposed by Jean-Pierre Kahane in 1957.

关键词： Mean periodic functions almost periodic functions trigonometric sums

KNOWLEDGE PROCESS ANALYSIS:FRAMEWORK AND EXPERIENCE

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Journal of Systems Science and Systems Engineering 2008年第1期17卷 86-108页

作者： Kozo SUGIYAMA Bertolt meyer School of Knowledge Science Japan Advanced Institute of Science and TechnologyIshikawaJapan Institute of Psychology University of ZurichSwitzerland

We present a step-by-step approach for constructing a framework for knowledge process analysis （KPA）. We intend to apply this framework to the analysis of own research projects in an exploratory way and elaborate it through the accumulation of case studies. This study is based on a methodology consisting of knowledge process modeling, primitives synthesis, and reflective verification. We describe details of the methodology and present the results of case studies： a novel methodology, a practical work guide, and a tool for KPA; insights for improving future research projects and education; and the integration of existing knowledge creation theories.

关键词： Knowledge process analysis knowledge process modeling primitives synthesis reflective verification

First ovules integument: what roles?

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National Science Review 2022年第4期9卷 21-22页

作者： Brigitte meyer-Berthaud AMAP Universit ?e de MontpellierCNRSCIRADINRAEIRD

The Famennian is a period of increased taxonomic diversity for the first representatives of the major plant groups,especially the spermatophytes (*** seed plants) that,today,represent the most abundant and diversified plant group on Earth [1,2].Early spermatophytes evolved a unique ovule-centered reproductive syndrome that allowed them to germinate and grow rapidly in disturbed habitats and,secondarily,to colonize dry habitats unfavorable to the reproduction of their free-sporing predecessors [3,4](Fig.1).In these ovulate organisms,the female gametophyte grows and produces gametes inside the indehiscent megasporangium (nucellus) that differentiates a pollen chamber retaining the pollen grains in its apical *** integument encloses the *** the Runcaria protovule that preceded them by 20 million years,Famennian ovules were all surrounded by a cupule,except perhaps Spermolithus and Warsteinia [5-7].

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Trigonometric multiplicative chaos and applications to random distributions

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Science China Mathematics 2023年第1期66卷 3-36页

作者： Aihua Fan Yves meyer School of Mathematics and Statistics Central China Normal UniversityWuhan 430079China LAMFA CNRSUMR7352University of PicardieAmiens 80039France CMLA ENS-CachanCNRSUniversityof Paris-SaclayParis 91190France

The random trigonometric series∑∞n=1ρn cos(nt+ωn)on the circle T are studied under the conditions∑|ρn|^(2)=∞andρn→0,where{ωn}are independent and uniformly distributed random variables on *** are almost surely not Fourier-Stieltjes series but determine *** leads us to develop the theory of trigonometric multiplicative chaos,which produces a class of random *** kernel and the image of chaotic operators are fully studied and the dimensions of chaotic measures are exactly *** behavior of the partial sums of the above series is proved to be *** theory holds on the torus Tdof dimension d≥1.

关键词： multiplicative chaos random Fourier series Hausdorff dimension Riesz potential

Pathology-induced NG2 proteoglycan expression in microglia

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Neural Regeneration Research 2023年第4期18卷 801-802页

作者： Erika meyer Anja Scheller Molecular Physiology Center for Integrative Physiology and Molecular MedicineUniversity of SaarlandHomburgGermany(Meyer EScheller A)Laboratory of Brain Ischemia and NeuroprotectionDepartment of Pharmacology and TherapeuticsState University of MaringáMaringáBrazil

Oligodendrocyte precursor cells(OPCs)and microglia are two very fascinating cell types with a multitude of important but different *** a first glance,they appear not to share many cellular properties,nor are directly related to one another or derived from a common *** all differences,emerging data show that both cell types express the protein nerve/glial antigen 2(NG2)after pathological insults(Figure 1).For years,it remained controversial whether microglia really could express NG2 upon injury,with contradictory results reported among different disease *** this question,we could recently show by using triple transgenic knock-in mice and either an acute injury model(stab wound injury)or the middle cerebral artery occlusion combined with immunohistochemistry that a subset of microglia activates the cspg4 gene in a disease dependent manner leading to a bonafide microglia-specific NG2 protein expression besides OPCs and *** data show that the cspg4 gene not only gets transcribed in microglia based on reporter expression after recombination,but also the protein itself is expressed(Huang et al.,2020).

关键词： NG2 wound Figure

Reconstruction of paleocoastlines for the northwestern South China Sea since the Last Glacial Maximum

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Science China Earth Sciences 2009年第8期52卷 1127-1136页

作者： HARFF Jan meyer Michael Leibniz Institute for Baltic Sea Research Warnemünde

The range of relative sea level rise in the northwestern South China Sea since the Last Glacial Maximum was over 100 m. As a result, lowland regions including the Northeast Vietnam coast, Beibu Gulf, and South China coast experienced an evolution from land to sea. Based on the principle of reconstructing paleogeography and using recent digital elevation model, relative sea level curves, and sediment accumulation data, this paper presents a series of paleogeographic scenarios back to 20 cal. ka BP for the northwestern South China Sea. The scenarios demonstrate the entire process of coastline changes for the area of interest. During the late glacial period from 20 to 15 cal. ka BP, coastline slowly retreated, causing a land loss of only 1×104 km2, and thus the land-sea distribution remained nearly unchanged. Later in 15-10 cal. ka BP coastline rapidly retreated and area of land loss was up to 24×104 km2, causing lowlands around Northeast Vietnam and South China soon to be underwater. Coastline retreat continued quite rapidly during the early Holocene. From 10 to 6 cal. ka BP land area had decreased by 9×104 km2, and during that process the Qiongzhou Strait completely opened up. Since the mid Holocene, main controls on coastline change are from vertical crustal movements and sedimentation. Transgression was surpassed by regression, resulting in a land accretion of about 10×104 km2.

关键词： relative sea level change paleocoastline reconstruction Last Glacial Maximum northwestern South China Sea

Superlubricity on the nanometer scale

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Friction 2014年第2期2卷 106-113页

作者： Ernst meyer Enrico GNECCO Department of Physics University of BaselKlingelbergstr.824056 BaselSwitzerland IMDEA Nanociencia Campus Universitario de CantoblancoCalle Faraday 928049 MadridSpain

The transition from atomic stick-slip to continuous sliding has been observed in a number of *** extended contacts are moved in different directions,so-called structural lubricity is observed when the two surface lattices are ***,a“superlubric”state of motion can be achieved if the normal force is reduced below a certain threshold,the temperature is increased,or the contact is actuated *** processes have been partially demonstrated using atomic force microscopy,and they can be theoretically understood by proper modifications of the Prandtl−Tomlinson model.

关键词： structural lubricity dynamic superlubricity atomic force microscopy friction force microscopy themolubricity Prandtl−Tomlinson model

Determination of particle exchange rates at over-flow weirs in horizontal fluidised beds by particle tracking velocimetry

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Particuology 2017年第3期15卷 1-9页

作者： Katja meyer Andreas Buck Evangelos Tsotsas Thermal Process Engineering Otto von Guericke University Magdeburg UniversitStsplatz 2 D-39106 Magdeburg Germany

Residence time distributions （RTDs） in horizontal fluidised beds have a huge effect on solid product properties and are infuenced by the internal design of the apparatus, e.g. the separation into different compartments by weirs. Weirs can be passed in or against the overall solid transport direction, with the back-flow resulting in axial dispersion, which is a measure of the spread of the RTD. Therefore, the ratio of exchange rates at weirs under different fluidisation conditions provides information on axial dispersion. In this work, a methodology based on particle tracking velocimetry is presented to obtain information on the exchange rates of particles at weirs in horizontal fluidised beds. The internal recirculation is studied for over-flow weirs with respect to different fluidisation conditions, providing a first step towards determining the effects of weirs and fluidisation conditions on axial dispersion and RTDs in horizontal fluidised beds.

关键词： Particle tracking velocimetry Horizontal fluidised bedAxial dispersion Granulation Drying

The contribution of small leaks in a baghouse filter to dust emission in the PM2.s range-A system approach

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Particuology 2017年第1期15卷 40-52页

作者： Oliver Kurtz Jorg meyer Gerhard Kasper Institut for Mechanische Verfahrenstechnik und Mechanik Karlsruhe Institute of Technology 76131 Karlsruhe Germany Freudenberg Filtration Technologies 69465 WeinheimGermany.

The contribution of leakage in a baghouse filter （defined as a short circuit between the upstream and downstream sides of the filter） to the emission of fine particles is quantified in comparison to other dust emission sources, and the influence of key operating variables on overall system response is analyzed. The study was conducted on a well-maintained pilot-scale filter unit （9 bags of 500 g/m^2 calendered polyester needle felt; total surface area 4.2 m^2） operated in Ap-controlled mode over a range of pulsing intensities, with two types of test dust （one free-flowing and the other cohesive） at inlet concentrations of 10 and 30 g/m^3. Leaks included single holes between 0.5 and 4 mm diameter, intentionally placed in either the plenum plate or one of the filter bags, as well as seamlines from bag confectioning. Emissions were sep- arated by source into a transient contribution due to dust penetration through the filter bags after each cleaning pulse, and a continuous contribution from leaks. This separation was based on a novel method of data processing that relies on time-resolved concentration measurements with a specially calibrated optical particle counter. Tiny leaks on the order of 1 mm generated the same emission level as all the bags combined, and dominated continuous emissions. The equivalent leak cross section （leakage = media emission） was about 1 ppm of the total installed filter surface, independent of upstream dust concentra- tion. Leakage through open seamlines amounted to 75% of media emissions in case of free-flowing test dust. Leakage was restricted to aerodynamic diameters less than ~5 μm （roughly the PM2.s mass frac- tion）. For comparison, time-averaged mass penetration through conventional needle-felt media ranged from about 10^-5 to 10^-6, depending on cohesiveness of the particle material and pulse cleaning intensity, giving emission levels between about 0.02 and 0.2 mg/m^3 at the reference concentration of 10 R/m^2.

关键词： Air filtration Baghouse Pulse-cleaned filters Leaks PM2.5 Dust emission