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Particuology 2008年第6期6卷 404-411页

作者： richard Caulkin Mike Fairweather richard A. Williams Institute of Particle Science and Engineering School of ProcessEnvironmental and Materials EngineeringUniversity of Leeds

This work presents a review of the findings into the ability of a digitally based particle packing algorithm, called DigiPac, to predict bed structure in a variety of packed columns, for a range of generic pellet shapes frequently used in the chemical and process engineering industries. Resulting macroscopic properties are compared with experimental data derived from both invasive and non-destructive measurement techniques. Additionally, fluid velocity distributions, through samples of the resulting bed structures, are analysed using lattice Boltzmann method （LBM） simulations and are compared against experimental data from the literature.

关键词： Packing algorithm Bed structure Packed columns Macroscopic properties Lattice Boltzmann simulations

Expected adult lifespan in tropical trees: Long-term matrix demography in a large plot

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Forest Ecosystems 2022年第4期9卷 558-566页

作者： richard Condit Morton Arboretum 4100 Illinois Rte.53LisleIL60532USA Institute for Marine Sciences University of CaliforniaSanta CruzUSA

Background: Documenting the entire lifetime of long-lived organisms requires splicing together short-term observations. Matrix demography provides a tool to calculate lifetime statistics, but large samples from juvenile to adult are needed, and few such studies have been done in tropical trees because high species diversity limits sample sizes. The 50-ha plot at Barro Colorado in Panama was designed to provide large samples, and with 30years of censuses, accurate population matrices can be ***: In 31 abundant species, I divided all individuals≥1 cm dbh into 4 or 5 size class in each of seven censuses. Movements of stems between size classes over two censuses are termed transitions, and I constructed complete transition matrices for each species. From the matrices, I derived analytic solutions for lifetime demographic statistics. Expected adult lifespan from the sapling stage was the key ***: Expected adult lifespan from the sapling stage varied 100-fold over the 31 species, from 0.5 to 50 years,and maturation time varied from 19 to nearly 200 years. Species with the highest growth rates also had high death rates, and theoretical calculations of reproductive lifespan show that the fast-growing pioneer species have short expected adult lifespans relative to the average slow-growing, shade-tolerant species. Within the slowgrowth category, however, there was high variation in expected adult lifespan, and several shade-tolerant species under-performed the pioneers in terms of adult ***: Analytical solutions from population matrices allow theoretical analyses that integrate short-term growth records into lifespans of tropical trees. The analyses suggest that pioneer species must reproduce more successfully than shade-tolerant species to persist in the Barro Colorado forest. My next goal is to incorporate seed production and germination into lifetime matrix demography to test this hypothesis.

关键词： Tree lifespan Tropical tree Matrix demography

Bound and Resonating Multiquark Configurations

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Chinese Physics Letters 2024年第8期41卷 8-12页

作者： Jean-Marc richard Institut de Physique des 2 Infinis de Lyon Université Claude Bernard(Lyon 1) CNRS-IN2P34 rue Enrico Fermi69622 VilleurbanneFrance

We review the predictions of quark models for multiquark configurations that are bound or resonant states,and compare different methods for estimating the properties of resonances.

关键词： quark Configuration resonant

CONTROLLING ROBOT MANIPULATORS BY DYNAMIC PROGRAMMING

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Acta Mechanica Sinica 1995年第1期11卷 20-33页

作者： MarcJ.richard Department

A certain number of considerations should be taken into account in the dynamic control of robot manipulators as highly complex non-linear *** this article,we provide a detailed presentation of the mechanical and electrical impli- cations of robots equipped with DC motor *** model takes into account all non-linear aspects of the ***,we develop computational algorithms for optimal control based on dynamic *** robot's trajectory must be predefined,but performance criteria and constraints applying to the system are not limited and we may adapt them freely to the robot and the task being *** an example,a manipulator arm with 3 degrees of freedom is analyzed.

关键词： dynamic programming robot manipulators optimal control dynamic modelling method

Large scale manufacture of magnetic polymer particles using membranes and microfluidic devices

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China Particuology 2007年第1期5卷 26-42页

作者： richard A. Williams Institute of Particle Science and Engineering School of Process Environmental and Materials Engineering University of Leeds Clarendon Road Leeds LS2 9JT United Kingdom

Magnetic polymer particles have found applications in diverse areas such as biomedical treatments, diagnosis and separation technology. These applications require the particles to have controlled sizes and narrow size distributions to gain better control and reproducibility in use. This paper reviews recent developments in the preparation of magnetic polymer particles at nano- and micro-scales by encapsulating magnetic components with dissolved or in situ formed polymers. Particle manufacture using emulsification and embedment methods produces magnetic polymer particles at micro-scale dimensions. However, the production of particles in this range using conventional emulsification methods affords very limited control over particle sizes and polydispersity. We report on alternative routes using membrane and microfluidics emulsification techniques, which have a capability to produce monodisperse emulsions and polymer microspheres （with coefficients of variation of less than 10%） in the range from submicrometer to a few 100 μm. The performance of these manufacturing methods is assessed with a view to future applications.

关键词： Magnetic polymer particles Membrane emulsification Microfluidics emulsification Large scale manufacture

Optimal chunk caching in network coding-based qualitative communication

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Digital Communications and Networks 2022年第1期8卷 44-50页

作者： Lijun Dong richard Li Futurewei Technologies Inc. 2330 Central ExpresswaySanta Clara95050USA

Network processing in the current Internet is at the entirety of the data packet,which is problematic when encountering network *** newly proposed Internet service named Qualitative Communication changes the network processing paradigm to an even finer granularity,namely chunk level,which obsoletes many existing networking policies and schemes,especially the caching algorithms and cache replacement policies that have been extensively explored in Web Caching,Content Delivery Networks(CDN)or Information-Centric Networks(ICN).This paper outlines all the new factors that are brought by random linear network coding-based Qualitative Communication and proves the importance and necessity of considering them.A novel metric is proposed by taking these new factors into *** optimization problem is formulated to maximize the metric value of all retained chunks in the local storage of network nodes under the constraint of storage limit.A cache replacement scheme that obtains the optimal result in a recursive manner is proposed *** the help of the introduced intelligent cache replacement algorithm,the performance evaluations show remarkably reduced end-to-end latency compared to the existing schemes in various network scenarios.

关键词： Internet Qualitative communication New IP Chunk caching Random linear network coding End-to-end latency Cache replacement policy Degree of freedom Distance Packet size

Optimal orientations of discrete global grids and the Poles of Inaccessibility

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International Journal of Digital Earth 2020年第7期13卷 803-816页

作者： richard Barnes Energy&Resources Group BerkeleyUSA Electrical Engineering&Comptuer Science BerkeleyUSA

Spatial analyses involving binning often require that every bin have the same area,but this is impossible using a rectangular grid laid over the Earth or over any projection of the *** global grids use hexagons,triangles,and diamonds to overcome this issue,overlaying the Earth with equally-sized *** discrete global grids are formed by tiling the faces of a ***,the orientations of these polyhedra have been chosen to satisfy only simple criteria such as equatorial symmetry or minimizing the number of vertices intersecting ***,projection distortion and singularities in discrete global grids mean that such simple orientations may not be sufficient for all use ***,I present an algorithm for finding suitable orientations;this involves solving a nonconvex optimization *** a side-effect of this study I show that Fuller’s Dymaxion map corresponds closely to one of the optimal orientations I find.I also give new high-accuracy calculations of the Poles of Inaccessibility,which show that Point Nemo,the Oceanic Pole of Inaccessibility,is 15 km farther from land than previously recognized.

关键词： Discrete grid geographic information system(GIS) geoinformatics supercomputer projections spatial statistics

Soundscapes and the sense of hearing of fishes

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Integrative Zoology 2009年第1期4卷 26-32页

作者： richard FAY Parmly Hearing Institute Loyola University ChicagoChicagoUSA

Underwater soundscapes have probably played an important role in the adaptation of ears and auditory systems of fishes throughout evolutionary time,and for all *** sounds probably contain important information about the environment and about most objects and events that confront the receiving fish so that appropriate be-havior is *** example,the sounds from reefs appear to be used by at least some fishes for their orientation and *** sorts of environmental sounds should be considered much like“acoustic daylight,”that continuously bathes all environments and contain information that all organisms can potentially use to form a sort of image of the *** present,however,we are generally ignorant of the nature of ambient sound fields impinging on fishes,and the adaptive value of processing these fields to resolve the multiple sources of *** field has focused almost exclusively on the adaptive value of processing species-specific communication sounds,and has not considered the informational value of ambient“noise.”Since all fishes can detect and process acoustic particle motion,including the directional characteristics of this motion,underwater sound fields are potentially more complex and information-rich than terrestrial acoustic *** capacities of one fish species(goldfish)to receive and make use of such sound source information have been demonstrated(sound source seg-regation and auditory scene analysis),and it is suggested that all vertebrate species have this capacity.A call is made to better understand underwater soundscapes,and the associated behaviors they determine in fishes.

关键词： acoustic daylight auditory scene analysis soundscape sound source segregation.

Combining scanning tunneling microscope (STM) imaging and local manipulation to probe the high dose oxidation structure of the Si(111)-7×7 surface

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Nano Research 2020年第1期13卷 145-150页

作者： Dogan Kaya richard J.Cobley richard E.Palmer Department of Electronics and Automation Vocational School of AdanaCukurova University01160CukurovaAdanaTurkey Nanoscale Physics Research Laboratory School of Physics and AstronomyUniversity of BirminghamEdgbastonBirminghamB152TTUK College of Engineering Swansea UniversityBay CampusFabian WaySwanseaSA18ENUK

Understanding the atomistic formation of oxide layers on semiconductors is important for thin film fabrication,scaling down conventional devices and for the integration of emerging research ***,the initial oxidation of Si(111)is studied using the scanning tunneling *** to the complete saturation of the silicon surface with oxygen,we are able to probe the atomic nature of the oxide layer *** establish the threshold for local manipulation of inserted oxygen sites to be+3.8 *** by combining imaging with local atomic manipulation are we able to determine whether inserted oxygen exists beneath surface-bonded oxygen sites and differentiate between sites that have one and more than one oxygen atom inserted beneath the *** to the creation of the thin oxide film we observe a flip in the manipulation rates of inserted oxygen sites consistent with more oxygen inserting beneath the silicon surface.

关键词： scanning tunneling microscopy(STM) local manipulation Si(111) oxidation