4,583 research outputs found

    Inhibited 1,1,1-trichloroethane replaces trichloroethylene for degreasing

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    In fight against air pollution inhibited TCE /1,1,1-trichloroethane/ is effective substitute for trichloroethylene in degreasing plants. This chemical has only slight photochemical activity and causes little eye irritation. TCE is less toxic than trichloroethylene and can withstand production loads and conditions, or long term storage, without degradation

    Calibration and testing of a TLD dosemeter for area monitoring

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    The response of a TLD-600/TLD-700 area dosemeter has been characterized in neutron fields around the 590 MeV cyclotron ring at the Paul Scherrer Institute (PSI). The dosemeter is based on a cylindrical paraffin moderator with three of each type of TLD chip at the centre, and is intended to use for area monitoring around accelerator facilities. The dosemeter is calibrated in terms of ambient dose equivalent using a non-moderated 252Cf neutron source. The ambient dose equivalent response has been tested in five locations where the neutron fields and dose rates have been well characterized by Bonner sphere spectrometer and active neutron monitor measurements. The different spectrum shapes and dose rates in the five locations permit the comparison of the behavior of the active and passive dosemeters in these neutron field

    Soft Photoproduction Physics

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    Several topics of interest in soft photoproduction physics are discussed. These include jet universality issues (particle flavour composition), the subdivision into event classes, the buildup of the total photoproduction cross section and the effects of multiple interactions.Comment: 10 pages, LaTeX2e, no figures, to appear in the proceedings of the Durham Workshop on HERA Physics, ``Proton, Photon and Pomeron Structure'', 17--23 September 1995, Durham, U.

    Has the QCD RG-Improved Parton Content of Virtual Photons been Observed?

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    It is demonstrated that present e+ee^+e^- and DIS ep data on the structure of the virtual photon can be understood entirely in terms of the standard `naive' quark--parton model box approach. Thus the QCD renormalization group (RG) improved parton distributions of virtual photons, in particular their gluonic component, have not yet been observed. The appropriate kinematical regions for their future observation are pointed out as well as suitable measurements which may demonstrate their relevance.Comment: 24 pages, LaTeX, 5 figure

    Color-Octet Charmonium Production in Top Quark Decays

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    We calculate the direct production rate of J/ψJ/\psi in top quark decays. The color-octet J/ψJ/\psi production via tW+bJ/ψt\rightarrow W^+ b J/\psi is shown to have a large branching ratio of order 1.5×1041.5\times 10^{-4}, which is over an order of magnitude higher than that of the color-singlet J/ψJ/\psi production via tW+bJ/ψ g gt\rightarrow W^+ b J/\psi~g~g or tW+b χcJ gt\rightarrow W^+ b~\chi_{cJ}~g followed by χcJJ/ψ γ\chi_{cJ}\rightarrow J/\psi~\gamma. This result can be used as a powerful tool to test the importance of the color-octet mechanism in heavy quarkonium production.Comment: 10 pages LaTex (2 figures in PS-file

    Resonant Production of Scalar Diquarks at the Next Generation Electron-Positron Colliders

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    We investigate the potential of TESLA and JLC/NLC electron-positron linear collider designs to observe diquarks produced resonantly in processes involving hard photons.Comment: 14 pages, 8 figures, coded in RevTEX, uses epsfi

    Parameter uncertainty analysis for an operational hydrological model using residual-based and limits of acceptability approaches

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    Parameter uncertainty estimation is one of the major challenges in hydrological modeling. Here we present parameter uncertainty analysis of a recently released distributed conceptual hydrological model applied in the Nea catchment, Norway. Two variants of the generalized likelihood uncertainty estimation (GLUE) methodologies, one based on the residuals and the other on the limits of acceptability, were employed. Streamflow and remote sensing snow cover data were used in conditioning model parameters and in model validation. When using the GLUE limit of acceptability (GLUE LOA) approach, a streamflow observation error of 25&thinsp;% was assumed. Neither the original limits nor relaxing the limits up to a physically meaningful value yielded a behavioral model capable of predicting streamflow within the limits in 100&thinsp;% of the observations. As an alternative to relaxing the limits, the requirement for the percentage of model predictions falling within the original limits was relaxed. An empirical approach was introduced to define the degree of relaxation. The result shows that snow- and water-balance-related parameters induce relatively higher streamflow uncertainty than catchment response parameters. Comparable results were obtained from behavioral models selected using the two GLUE methodologies.</p

    Compilação e organização de parâmetros físicos de solos da Bacia do Pito Aceso para aplicação no sistema de modelagem hidrológica JAMS.

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    A escolha de um modelo hidrológico apropriado para uso em dada bacia deve considerar o acesso e custo do software, a viabilidade de aplicação, a disponibilidade e compatibilidade dos dados de entrada, bem como a familiaridade do usuário com os métodos de resolução. Devido às dificuldades e restrições de uso de alguns modelos de precipitação-vazão, a Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), no Centro Nacional de Pesquisa em Solos (CNPS), iniciou pesquisa visando à avaliação do uso do Sistema de Modelagem Adaptável de Jena (JAMS). Este estudo, fruto da parceria da Embrapa com a Universidade de Jena, busca a construção de um modelo precipitação-vazão que simule o escoamento superficial da microbacia do Córrego do Pito Aceso, inserida na Bacia do Rio Paraíba do Sul e localizada no município de Bom Jardim, região serrana do Rio de Janeiro - RJ. O objetivo deste trabalho foi compilar e organizar informações sobre modelagem hidrológica, trabalhos e teses publicadas sobre o local de estudo, bem como os dados disponíveis da microbacia, e artigos e teses sobre o sistema JAMS e suas aplicações. Foi possível identificar também as necessidades de novos dados e parâmetros a serem coletados

    Multiple Interactions in Two-Photon Collisions

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    We compute cross sections for events where two pairs of partons scatter off each other in the same γγ\gamma\gamma reaction, giving rise to at least 3 high--{\mbox{pTp_T^{}}} jets. Unlike in {\mbox{ppˉp \bar p}}\ collisions we find the signal to lie well above the background from higher order QCD processes. If the usual ``eikonaliztion" assumption is correct, the signal should be readily observable at LEP2, and might already be detectable in data taken at TRISTAN.Comment: 8 pages, plain LaTeX, 2 figures (not included). A compressed PS file of the entire paper, including figures, can be obtained via anonymous ftp from ftp://phenom.physics.wisc.edu/pub/preprints/1995/madph-95-921.ps.
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