27,762 research outputs found

    European Organic Production Statistics 1993 - 1996

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    Detailed official statistics on organic farming in Europe are scarce. This volume is the most authoritative source for statistical data on organic farming with respect to land area, number of farms, livestock and crop production for all EU member countries plus Norway, Switzerland and the Czech Republic. Time series are provided from 1993 - 1996. This book is essential reading for policy makers, the private sector, researchers and students in the field of economics and politics of organic farming

    Technical publications of the NASA Wallops Flight Facility, 1980 through 1983

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    This bibliography lists the publications sponsored by the NASA Wallops Flight Center/NASA Goddard Space Flight Center, Wallops Flight Facility during the period 1980 through 1983. The compilation contains citations listed by type of publication; i.e., NASA formal report, NASA contractor report, journal article, or presentation; by contract/grant number; and by accession number. Oceanography, astrophysics, artificial satellites, fluid mechanics, and sea ice are among the topics covered

    Forty Years of Celebration of Discipline: An Interview with Richard Foster

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    Wow, Richard, it’s been 40 years since your first book, Celebration of Discipline, was published, and it’s still a best seller (selling over 2 million copies), having been translated into 25 languages! Reflecting on that now, could you say something about your original vision for the book, and how God has blessed its impact over the years

    MPICH-G2: A Grid-Enabled Implementation of the Message Passing Interface

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    Application development for distributed computing "Grids" can benefit from tools that variously hide or enable application-level management of critical aspects of the heterogeneous environment. As part of an investigation of these issues, we have developed MPICH-G2, a Grid-enabled implementation of the Message Passing Interface (MPI) that allows a user to run MPI programs across multiple computers, at the same or different sites, using the same commands that would be used on a parallel computer. This library extends the Argonne MPICH implementation of MPI to use services provided by the Globus Toolkit for authentication, authorization, resource allocation, executable staging, and I/O, as well as for process creation, monitoring, and control. Various performance-critical operations, including startup and collective operations, are configured to exploit network topology information. The library also exploits MPI constructs for performance management; for example, the MPI communicator construct is used for application-level discovery of, and adaptation to, both network topology and network quality-of-service mechanisms. We describe the MPICH-G2 design and implementation, present performance results, and review application experiences, including record-setting distributed simulations.Comment: 20 pages, 8 figure

    A fast and robust numerical scheme for solving models of charge carrier transport and ion vacancy motion in perovskite solar cells

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    Drift-diffusion models that account for the motion of both electronic and ionic charges are important tools for explaining the hysteretic behaviour and guiding the development of metal halide perovskite solar cells. Furnishing numerical solutions to such models for realistic operating conditions is challenging owing to the extreme values of some of the parameters. In particular, those characterising (i) the short Debye lengths (giving rise to rapid changes in the solutions across narrow layers), (ii) the relatively large potential differences across devices and (iii) the disparity in timescales between the motion of the electronic and ionic species give rise to significant stiffness. We present a finite difference scheme with an adaptive time step that is posed on a non-uniform staggered grid that provides second order accuracy in the mesh spacing. The method is able to cope with the stiffness of the system for realistic parameters values whilst providing high accuracy and maintaining modest computational costs. For example, a transient sweep of a current-voltage curve can be computed in only a few minutes on a standard desktop computer.Comment: 22 pages, 8 figure

    The Policy and Regulatory Environment for Organic Farming in Europe

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    Organic Farming is one of the key issues in reshaping European agricultural policy. This book clarifies the policy and regulatory environment within which organic farming currently operates in all EU-15 member states and in three non-EU countries (Norway, Switzerland and the Czech Republic). European and national regulations and their implementation are reviewed. Focus is led on agri-environmental and mainstream agricultural support measures, marketing and regional development programmes, certification systems and organic farming support in the form of advice, training and research. The book aims at policy makers, the private sector, researchers and students in the field of economics and politics of organic farming

    Sedentary behaviour and diet across the lifespan: an updated systematic review.

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    Sedentary behaviour and its association with dietary intake in young people and adults are important topics and were systematically reviewed in 2011. There is a need to update this evidence given the changing nature of sedentary behaviour and continued interest in this field. This review aims to assist researchers in better interpreting the diversity of findings concerning sedentary behaviour and weight status

    Analytical technique characterizes all trace contaminants in water

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    Properly programmed combination of advanced chemical and physical analytical techniques characterize critically all trace contaminants in both the potable and waste water from the Apollo Command Module. This methodology can also be applied to the investigation of the source of water pollution

    GA tuning of pitch controller for small scale MAVs

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    The paper presents the application of intelligent tuning methods for the control of a prototype MAV in order to address problems associated with bandwidth limited actuators and gust alleviation. Specifically, as a proof of concept, the investigation is focused on the pitch control of a MAV. The work is supported by experimental results from wind tunnel testing that shows the merits of the use of Genetic Algorithm (GA) tuning techniques compared to classical, empirical tuning methodologies. To provide a measure of relative merit, the controller responses are evaluated using the ITAE performance index. In this way, the proposed method is shown to induce far superior dynamic performance compared to traditional approaches
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