14,056 research outputs found

    Outcomes of CCAFS Work in Vietnam

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    The study explored how CCAFS SEA outputs have helped the country achieve its development outcomes in the agricultural sector. The assessment showed that CCAFS SEA, although still on-going, has contributed to specific outcomes in Vietnam, which include changes in knowledge, approaches, practices, and strategies related to climate change, particularly in the agricultural sector. These outcomes were observed among decision makers, policymakers, technical staff, and farmers

    Effects of Bose-Einstein Condensation on forces among bodies sitting in a boson heat bath

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    We explore the consequences of Bose-Einstein condensation on two-scalar-exchange mediated forces among bodies that sit in a boson gas. We find that below the condensation temperature the range of the forces becomes infinite while it is finite at temperatures above condensation.Comment: 10 pages, 2 figure

    Revision of the types of species of Alloxysta described by Cameron and Fergusson (Hymenoptera: Figitidae: Charipinae) and deposited in the Natural History Museum (London), including a key to the fauna of Great Britain

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    Type material of the species of Alloxysta described by Cameron and Fergusson and deposited in the Natural History Museum of London has been revised. Seven species are considered valid: Alloxysta abdera Fergusson, 1986, A. basimacula (Cameron, 1886), A. crassa (Cameron, 1889), A. mullensis (Cameron, 1883), A. piceomaculata (Cameron, 1883), A. pleuralis (Cameron, 1879) and A. semiaperta Fergusson, 1986. A. basimacula, A. crassa, A. maculicollis (Cameron, 1886), A. perplexa (Cameron, 1889) and A. piceomaculata are here removed from synonymy with A. macrophadna (Hartig, 1841). A. rufi ceps (Cameron, 1883) is removed from synonymy with A. victrix (Westwood, 1833). A. caledonica (Cameron, 1886) and A. perplexa are here synonymized with A. basimacula. A. maculicollis, A. ruficeps and A. ruficollis (Cameron, 1883) are here synonymized with A. castanea (Hartig, 1841). A. ancylocera (Cameron, 1886) was correctly synonymized with A. fuscicornis (Hartig, 1841), A. curvicornis (Cameron, 1883) was correctly synonymized with A. victrix and A. filicornis (Cameron, 1889) was correctly synonymized with A. macrophadna. Complete redescriptions and illustrations are given for valid species. A key for all the Alloxysta species found so far in Great Britain is given

    Long range neutrino forces in the cosmic relic neutrino background

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    Neutrinos mediate long range forces among macroscopic bodies in vacuum. When the bodies are placed in the neutrino cosmic background, these forces are modified. Indeed, at distances long compared to the scale T−1T^{-1}, the relic neutrinos completely screen off the 2-neutrino exchange force, whereas for small distances the interaction remains unaffected.Comment: 8 pages, 2 figure

    Demographic growth and the distribution of language sizes

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    It is argued that the present log-normal distribution of language sizes is, to a large extent, a consequence of demographic dynamics within the population of speakers of each language. A two-parameter stochastic multiplicative process is proposed as a model for the population dynamics of individual languages, and applied over a period spanning the last ten centuries. The model disregards language birth and death. A straightforward fitting of the two parameters, which statistically characterize the population growth rate, predicts a distribution of language sizes in excellent agreement with empirical data. Numerical simulations, and the study of the size distribution within language families, validate the assumptions at the basis of the model.Comment: To appear in Int. J. Mod. Phys. C (2008

    Analysis on Combined Heat and Power, and Combined Heat and Power Hybrid Systems for Unconventional Drilling Operations

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    The United States (U.S.) has experienced a natural gas “boom” due to the development of unconventional shale plays, but well development is energy intensive. Operations use electric drilling rigs typically powered by either three high-horsepower diesel engines (HHPDE) or three dedicated natural gas engines (DNGE) and associated generators. From a first law analysis, HHPDEs peak at 42% efficiency at full load, while DNGE peak at about 30%. Most of the fuel energy is lost as heat rejected by the exhaust and radiators. Concurrently, during cold seasons rigs utilize boilers to provide steam throughout the rig to prevent freezing and provide comfort. The U.S. Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) recently granted West Virginia University (WVU) funding, under agreement DE-FE0024297, to “develop and validate new knowledge and technology to improve recovery efficiency and minimize environmental implications of unconventional resource development.” As part of the funding, WVU was tasked with auditing the energy consumption during the horizontal drilling of an unconventional well, processing the data, and assessing methods to reduce fossil fuel consumption and associated emissions during the development phase. My research analysis focused on a combined heat power (CHP) approach as a means to improve the utilization factor (UF) of fossil energy consumed during development. Engine activity, boiler fuel consumption, and exhaust gas temperatures were recorded during winter drilling of an entire well in the Marcellus shale. Four characteristic activity cycles were extracted from recorded engine and boiler activity to represent four energy consumption scenarios. Exhaust and jacket water heat exchangers (E-HEX, JW-HEX) were designed and simulated, and results were analyzed in 0-D models for the four case scenarios. A 584-kWh hybrid energy management system (HEMS) was also designed and simulated into the model as another method to reduce fossil fuel energy consumption during well development. HHPDE UF improved on average from 35.7% to 55.7% if only E-HEXs were used and improved to 72.7% if JW-HEXs were also used. DNGEs were less efficient than HHPDE; therefore, more waste heat was available and at a higher quality (temperature). DNGE average UF increased from 19.0% to 34.9% using E-HEX only. HEMS utilization improved UF up to an average of 76.9% and 39.1% for HHPDE CHP and DNGE CHP systems, respectivel
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