Simple models of fluid flow at the core surface derived from geomagnetic field models     

Jeremy Bloxham 《Geophysical Journal International》1989,99(1):173-182

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Self-gravity and quasi-stellar object discs     

Jeremy Goodman 《Monthly notices of the Royal Astronomical Society》2003,339(4):937-948

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Toward an expert system for identification of minerals in thin section     

Jeremy West 《Mathematical Geology》1985,17(7):743-753

Minerals may be identified by optical inspection and x-ray diffraction analysis. Full and correct identification, however, requires experience and extensive knowledge of mineral characteristics and association. Computer systems designed to approach levels of human expertise in similarly complex identification tasks have become increasingly effective with the application and refinement of various Artificial Intelligence (AI) techniques. These knowledge-based systemsuse the skills, knowledge, and rules of thumb that distinguish the expert from the knowledgeable layman to emulate human expertise. They also may be modified to serve a tutorial role whereby a nonexpert's approach to the task may be compared with that of the expert (system), and criticized accordingly. Such a knowledge-based system capable of identifying minerals from their optical characteristics is being developed at the University of Reading.  相似文献   

Canonical Modelling of Relative Spacecraft Motion Via Epicyclic Orbital Elements     

N.?Jeremy?KasdinEmail author  Pini?Gurfil  Egemen?Kolemen 《Celestial Mechanics and Dynamical Astronomy》2005,92(4):337-370

This paper presents a Hamiltonian approach to modelling spacecraft motion relative to a circular reference orbit based on a derivation of canonical coordinates for the relative state-space dynamics. The Hamiltonian formulation facilitates the modelling of high-order terms and orbital perturbations within the context of the Clohessy–Wiltshire solution. First, the Hamiltonian is partitioned into a linear term and a high-order term. The Hamilton–Jacobi equations are solved for the linear part by separation, and new constants for the relative motions are obtained, called epicyclic elements. The influence of higher order terms and perturbations, such as Earth’s oblateness, are incorporated into the analysis by a variation of parameters procedure. As an example, closed-form solutions for J₂-invariant orbits are obtained.  相似文献   

Enthalpies and entropies of proton and cadmium adsorption onto Bacillus subtilis bacterial cells from calorimetric measurements     

Drew Gorman-Lewis  Jeremy B. Fein 《Geochimica et cosmochimica acta》2006,70(19):4862-4873

We used titration calorimetry to measure the bulk heats of proton and Cd adsorption onto a common Gram positive soil bacterium Bacillus subtilis at 25.0 °C. Using the 4-site non-electrostatic model of Fein et al. [Fein, J.B., Boily, J.-F., Yee, N., Gorman-Lewis, D., Turner, B.F., 2005. Potentiometric titrations of Bacillus subtilis cells to low pH and a comparison of modeling approaches. Geochim. Cosmochim. Acta69 (5), 1123-1132.] to describe the bacterial surface reactivity to protons, our bulk enthalpy measurements can be used to determine the following site-specific enthalpies of proton adsorption for Sites 1-4, respectively: −3.5 ± 0.2, −4.2 ± 0.2, −15.4 ± 0.9, and −35 ± 2 kJ/mol, and these values yield the following third law entropies of proton adsorption onto Sites 1-4, respectively: +51 ± 4, +78 ± 4, +79 ± 5, and +60 ± 20 J/mol K. An alternative data analysis using a 2-site Langmuir-Freundlich model to describe proton binding to the bacterial surface (Fein et al., 2005) resulted in the following site-specific enthalpies of proton adsorption for Sites 1 and 2, respectively: −3.6 ± 0.2 and −35.1 ± 0.3 kJ/mol. The thermodynamic values for Sites 1-3 for the non-electrostatic model and Site 1 of the Langmuir-Freundlich model of proton adsorption onto the bacterial surface are similar to those associated with multifunctional organic acid anions, such as citrate, suggesting that the protonation state of a bacterial surface site can influence the energetics of protonation of neighboring sites. Our bulk Cd enthalpy data, interpreted using the 2-site non-electrostatic Cd adsorption model of Borrok et al. [Borrok, D., Fein, J.B., Tischler, M., O’Loughlin, E., Meyer, H., Liss, M., Kemner, K.M., 2004b. The effect of acidic solutions and growth conditions on the adsorptive properties of bacterial surfaces. Chem. Geol.209 (1-2), 107-119.] to account for Cd adsorption onto B. subtilis, yield the following site-specific enthalpies of Cd adsorption onto bacterial surface Sites 2 and 3, respectively: −0.2 ± 0.4 and +14.4 ± 0.9 kJ/mol, and the following third law entropies of Cd adsorption onto Sites 2 and 3, respectively: +57 ± 4 and +128 ± 5 J/mol K. The calculated enthalpies of Cd adsorption are typical of those associated with Cd complexation with anionic oxygen ligands, and the entropies are indicative of inner sphere complexation by multiple ligands. The experimental approach described in this study not only yields constraints on the molecular-scale mechanisms involved in proton and Cd adsorption reactions, but also provides new thermodynamic data that enable quantitative estimates of the temperature dependence of proton and Cd adsorption reactions.  相似文献   

Geospatial Information Integration for Authoritative and Crowd Sourced Road Vector Data   总被引：1，自引：0，他引：1  

Heshan Du  Suchith Anand  Natasha Alechina  Jeremy Morley  Glen Hart  Didier Leibovici  Mike Jackson  Mark Ware 《Transactions in GIS》2012,16(4):455-476

This article describes results from a research project undertaken to explore the technical issues associated with integrating unstructured crowd sourced data with authoritative national mapping data. The ultimate objective is to develop methodologies to ensure the feature enrichment of authoritative data, using crowd sourced data. Users increasingly find that they wish to use data from both kinds of geographic data sources. Different techniques and methodologies can be developed to solve this problem. In our previous research, a position map matching algorithm was developed for integrating authoritative and crowd sourced road vector data, and showed promising results ( Anand et al. 2010 ). However, especially when integrating different forms of data at the feature level, these techniques are often time consuming and are more computationally intensive than other techniques available. To tackle these problems, this project aims at developing a methodology for automated conflict resolution, linking and merging of geographical information from disparate authoritative and crowd‐sourced data sources. This article describes research undertaken by the authors on the design, implementation, and evaluation of algorithms and procedures for producing a coherent ontology from disparate geospatial data sources. To integrate road vector data from disparate sources, the method presented in this article first converts input data sets to ontologies, and then merges these ontologies into a new ontology. This new ontology is then checked and modified to ensure that it is consistent. The developed methodology can deal with topological and geometry inconsistency and provide more flexibility for geospatial information merging.  相似文献   

U.S. National Forests adapt to climate change through Science–Management partnerships     

Jeremy S. Littell  David L. Peterson  Constance I. Millar  Kathy A. O’Halloran 《Climatic change》2012,110(1-2):269-296

Developing appropriate management options for adapting to climate change is a new challenge for land managers, and integration of climate change concepts into operational management and planning on United States national forests is just starting. We established science–management partnerships on the Olympic National Forest (Washington) and Tahoe National Forest (California) in the first effort to develop adaptation options for specific national forests. We employed a focus group process in order to establish the scientific context necessary for understanding climate change and its anticipated effects, and to develop specific options for adapting to a warmer climate. Climate change scientists provided the scientific knowledge base on which adaptations could be based, and resource managers developed adaptation options based on their understanding of ecosystem structure, function, and management. General adaptation strategies developed by national forest managers include: (1) reduce vulnerability to anticipated climate-induced stress by increasing resilience at large spatial scales, (2) consider tradeoffs and conflicts that may affect adaptation success, (3) manage for realistic outcomes and prioritize treatments that facilitate adaptation to a warmer climate, (4) manage dynamically and experimentally, and (5) manage for structure and composition. Specific adaptation options include: (1) increase landscape diversity, (2) maintain biological diversity, (3) implement early detection/rapid response for exotic species and undesirable resource conditions, (4) treat large-scale disturbance as a management opportunity and integrate it in planning, (5) implement treatments that confer resilience at large spatial scales, (6) match engineering of infrastructure to expected future conditions, (7) promote education and awareness about climate change among resource staff and local publics, and (8) collaborate with a variety of partners on adaptation strategies and to promote ecoregional management. The process described here can quickly elicit a large amount of information relevant for adaptation to climate change, and can be emulated for other national forests, groups of national forests with similar resources, and other public lands. As adaptation options are iteratively generated for additional administrative units on public lands, management options can be compared, tested, and integrated into adaptive management. Science-based adaptation is imperative because increasing certainty about climate impacts and management outcomes may take decades.  相似文献   

In situ measurements of contributions to the global electrical circuit by a thunderstorm in southeastern Brazil     

Jeremy N. Thomas  Robert H. Holzworth  Michael P. McCarthy 《Atmospheric Research》2009,91(2-4):153-160

The global electrical circuit, which maintains a potential of about 280 kV between the earth and the ionosphere, is thought to be driven mainly by thunderstorms and lightning. However, very few in situ measurements of electrical current above thunderstorms have been successfully obtained. In this paper, we present dc to very low frequency electric fields and atmospheric conductivity measured in the stratosphere (30–35 km altitude) above an active thunderstorm in southeastern Brazil. From these measurements, we estimate the mean quasi-static conduction current during the storm period to be 2.5 ± 1.25 A. Additionally, we examine the transient conduction currents following a large positive cloud-to-ground (+ CG) lightning flash and typical − CG flashes. We find that the majority of the total current is attributed to the quasi-static thundercloud charge, rather than lightning, which supports the classical Wilson model for the global electrical circuit.  相似文献   

Land surface coupling in regional climate simulations of the West African monsoon   总被引：6，自引：3，他引：3  

Allison L. Steiner  Jeremy S. Pal  Sara A. Rauscher  Jason L. Bell  Noah S. Diffenbaugh  Aaron Boone  Lisa C. Sloan  Filippo Giorgi 《Climate Dynamics》2009,33(6):869-892

Coupling of the Community Land Model (CLM3) to the ICTP Regional Climate Model (RegCM3) substantially improves the simulation of mean climate over West Africa relative to an older version of RegCM3 coupled to the Biosphere Atmosphere Transfer Scheme (BATS). Two 10-year simulations (1992–2001) show that the seasonal timing and magnitude of mean monsoon precipitation more closely match observations when the new land surface scheme is implemented. Specifically, RegCM3–CLM3 improves the timing of the monsoon advance and retreat across the Guinean Coast, and reduces a positive precipitation bias in the Sahel and Northern Africa. As a result, simulated temperatures are higher, thereby reducing the negative temperature bias found in the Guinean Coast and Sahel in RegCM3–BATS. In the RegCM3–BATS simulation, warmer temperatures in northern latitudes and wetter soils near the coast create excessively strong temperature and moist static energy gradients, which shifts the African Easterly Jet further north than observed. In the RegCM3–CLM3 simulation, the migration and position of the African Easterly Jet more closely match reanalysis winds. This improvement is triggered by drier soil conditions in the RegCM3–CLM3 simulation and an increase in evapotranspiration per unit precipitation. These results indicate that atmosphere–land surface coupling has the ability to impact regional-scale circulation and precipitation in regions exhibiting strong hydroclimatic gradients.  相似文献   

Preparing for climate change in Washington State     

Lara C. Whitely Binder  Jennifer Krencicki Barcelos  Derek B. Booth  Meriel Darzen  Marketa McGuire Elsner  Richard Fenske  Thomas F. Graham  Alan F. Hamlet  John Hodges-Howell  J. Elizabeth Jackson  Catherine Karr  Patrick W. Keys  Jeremy S. Littell  Nathan Mantua  Jennifer Marlow  Don McKenzie  Michael Robinson-Dorn  Eric A. Rosenberg  Claudio O. Stöckle  Julie A. Vano 《Climatic change》2010,102(1-2):351-376

Climate change is expected to bring potentially significant changes to Washington State’s natural, institutional, cultural, and economic landscape. Addressing climate change impacts will require a sustained commitment to integrating climate information into the day-to-day governance and management of infrastructure, programs, and services that may be affected by climate change. This paper discusses fundamental concepts for planning for climate change and identifies options for adapting to the climate impacts evaluated in the Washington Climate Change Impacts Assessment. Additionally, the paper highlights potential avenues for increasing flexibility in the policies and regulations used to govern human and natural systems in Washington.  相似文献