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A collaboration into research on nanoparticles (ACORN)

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Particuology 2009年第2期7卷 93-105页

作者： david G. Parker Chemistry Innovation The HeathRuncorn WA7 4QXUnited Kingdom

This paper describes the operation and outcome of one of the United Kingdom＇s largest multi-partner research activities in nanoparticles. The research covers the discovery and development of organic and inorganic crystals/nanoparticles, nanoparticle properties towards specific product applications. The research also encompassed bespoke measurement technology for nanoparticles and structure interactions. Significant research outcomes are summarised. The paper illustrates the advantages from industrially motivated research and value of collective action between a broad group of researchers in a nation.

关键词： Nanoparticles Nanoparticle manufacture Nanocrystals Nanoassembly structure Modelling

Plant conservation in Australia:Current directions and future challenges

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Plant Diversity 2017年第6期39卷 348-356页

作者： Linda Broadhurst david Coates CANBR CSIRO National Research Collections Australia Department of Biodiversity Conservation and Attractions

Australia is a large, old and flat island continent that became isolated following the breakup of the Gondwanan super continent. After more than 40-50 M years of independent evolution, approx. 600,000-700,000 species now call Australia home. More than 21,000 of these species are plants, with at least84% of these being endemic. Plant taxa are protected, conserved and managed under a range of legislation at the State-and Territory-level as well as Federally for matters of national significance. This can create issues of misalignment among threatened species lists but generally there is co-operation among conservation agencies to reduce misalignments and to manage species irrespective of jurisdictional borders. Despite significant investment in programs designed to assist the recovery of Australian biodiversity, threatened plants in particular appear to be continuing to decline. This can be attributed to a range of factors including major threatening processes associated with habitat loss and invasive species,lack of public awareness of the cultural and socio-economic value of plant conservation, and our relatively poor understanding of basic species taxonomy and biology, especially for those species that have specific interactions with pollinators, symbionts and herbivores. A recent shift in Federally-based conservation programs has been to identify 30 key plant species for recovery through the setting of measurable targets, improving the support provided to recovery teams and encouraging industry,business and philanthropy to support conservation actions.

关键词： Conservation Plant Australia Threatened species Recovery

Real-time solution of nonlinear potential flow equations for lifting rotors

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Chinese Journal of Aeronautics 2017年第3期30卷 871-880页

作者： Jianzhe HUANG david PETERS Department of Energy and Power Engineering Harbin Engineering University Department of Mechanical Engineering and Materials Science Washington University in St.Louis

Analysis of rotorcraft dynamics requires solution of the rotor induced flow ***,the appropriate model to be used for induced flow is nonlinear potential flow theory（which is the basis of vortex-lattice methods）.These nonlinear potential flow equations sometimes must be solved in real time––such as for real-time flight simulation,when observers are needed for controllers,or in preliminary design *** this paper,the major effects of nonlinearities on induced flow are studied for lifting rotors in low-speed flight and *** approach is to use a nonlinear statespace model of the induced flow based on a Galerkin treatment of the potential flow equations.

关键词： Mass-flow Nonlinear Potential flow Real-time flight simulator Rotorcraft dynamics Swirl Wake contraction

Valuation of Stock Loans Under a Markov Chain Model

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Journal of Systems Science & Complexity 2016年第1期29卷 171-186页

作者： PRAGER david ZHANG Qing Department of Mathematics Anderson University Department of Mathematics The University of Georgia

In recent years the use of Markov chain models to model stock price movement has received increased attention among *** chain models combine the discrete movements of a binomial tree model while retaining the Markovian properties of Brownian motion,thus allowing the best properties of both of these *** this paper,the authors consider a Markov chain model in which the underlying market is solely determined by a two-state Markov *** a Markov chain model is strikingly simple and yet appears capable of capturing various market *** proper selection of parameters,the Markov chain model can produce sample paths that are very similar *** very distinct from a classical Brownian motion,as the authors demonstrate in this *** paper studies the stock loan valuation,or the value of a loan in which a risky share of stock is used as collateral,under such a *** programming equations in terms of variational inequalities are used to capture the dynamics of the *** equations are solved in *** optimal solutions are *** examples are also reported to illustrate the results.

关键词： Closed-form solution Markov chain model stock loan

TOPOLOGY AND CASCADING LINE OUTAGES IN POWER GRIDS

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Journal of Systems Science and Systems Engineering 2007年第2期16卷 202-221页

作者： david L. PEPYNE University of Massachusetts Amherst MA USA

Motivated by the small world network research of Watts ＆ Strogatz, this paper studies relationships between topology and cascading line outages in electric power grids. Cascading line outages are a type of cascading collapse that can occur in power grids when the transmission network is congested. It is characterized by a self-sustaining sequence of line outages followed by grid breakup, which generally leads to widespread blackout. The main findings of this work are twofold： On one hand, the work suggests that topologies with more disorder in their interconnection topology tend to be robust with respect to cascading line outages in the sense of being able to support greater generation and demand levels than more regularly interconnected topologies. On the other hand, the work suggests that topologies with more disorder tend to be more fragile in that should a cascade get started, they tend to break apart after fewer outages than more regularly interconnected topologies. Thus, as has been observed in other complex networks, there appears to be a tradeoff between robustness and fragility. These results were established using synthetically generated power grid topologies and verified using the IEEE 57 bus and 188 bus power grid test cases.

关键词： Power grid blackout cascading line failure complex networks robust yet fragile

Cellular automata modelling of phase-change memories

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Journal of University of Science and Technology Beijing 2008年第4期15卷 444-450页

作者： Wanhua Yu david Wright School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Engineering Computer Science and Mathematics The University of Exeter Exeter EX4 4QF UK

A novel approach to modelling phase-transition processes in phase change materials used for optical and electrical data storage applications is presented. The model is based on a cellular automaton （CA） approach to predict crystallization behaviour that is linked to thermal and electrical simulations to enable the study of the data writing and erasing processes. The CA approach is shown to be able to predict the evolution of the microstructure during the rapid heating and cooling cycles pertinent to data storage technology, and maps crystallization behaviour on the nanoscale. A simple example based on possible future nonvolatile phase-change random access solid-state memory is presented.

关键词： crystallization bchaviour cellular automation computer simulation memory data storage modelling phase change

Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

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National Science Review 2024年第1期11卷 8-10页

作者： david J.Bottjer Department of Earth Sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

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Combining innovative science and policy to improve air quality in cities with refining and chemicals manufacturing： The case study of Houston, Texas, USA

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Frontiers of Chemical Science and Engineering 2017年第3期11卷 293-304页

作者： david T. Allen University of Texas Austin Department of Chemical Engineering and Center for Energy and Environmental Resources Austin TX 78759 USA

In Houston, a combination of urban emissions from a city of 4 million people, coupled with emissions from extensive petroleum refining and chemical manufacturing, leads to conditions for photochemistry that are unique in the United States, and historically, the city had experienced some of the highest ozone concentrations recorded in the United States. Large air quality field studies （the Texas Air Quality Studies or TexAQS I and II） were conducted to determine root causes of the high ozone concentrations. Hundreds of air quality investigators, from around the world, deployed instruments on aircraft, on ships, and at fixed ground sites to make extensive air quality measurements; detailed photochemical modeling was used to interpret and assess the implications of the measurements. The Texas Air Quality Studies revealed that both continuous and episodic emissions of light alkenes, which came to be called highly reactive volatile organic compounds, played a critical role in the formation of ozone and other photochemical oxidants in the region. Under- standing and quantifying the role of these emissions in regional air quality required innovations in characterizing emissions and in photochemical modeling. Reducing emissions required innovative policy approaches. These coupled scientific and policy innovations are described, and the result, substantially cleaner air for Houston, is documented. The lessons learned from the Houston air quality experience are relevant to cities with similar population and industrial profiles around the world.

关键词： ozone air quality highly reactive volatile organic compounds Houston

Cognitive ecology of pollinators and the main determinants of foraging plasticity

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Current Zoology 2019年第4期65卷 421-424页

作者： david Baracchi Dipartimento di Biologia Universita degli Studi di Firenze Via Madonna del Piano 6 Sesto Fiorentino Firenze 50019 Italy

Introduction The long-lasting coevolution between flowering plants and associate pollinators has made both partners intimately connected and reciprocally dependent on one another (Chittka and Thomson 2001;Harder and Barrett 2006;Waser and Oilerton 2006). The interaction between plants and pollinators rests mostly on a mutualistic exchange: plants invest in the production of nectar and pollen to reward pollinators who, in turn, sustain plant reproduction by vectoring their pollen to conspecific flowers (Harder and Barrett 2006;Waser and Oilerton 2006).

关键词： Cognitive ecology pollinators foraging