40 research outputs found

    Binding Energies and Scattering Observables in the ^3He^4He_2 Atomic System

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    The ^3He^4He_2 three-atomic system is studied on the basis of a hard-core version of the Faddeev differential equations. The binding energy of the ^3He^4He_2 trimer, scattering phase shifts, and the scattering length of a ^3He atom off a ^4He dimer are calculated using the LM2M2 and TTY He-He interatomic potentials.Comment: Contribution to Proceedings of the 17th International IUPAP Conference on Few-Body Problems in Physics (Durham, North Carolina, USA, June 5-10, 2003

    Large-basin hydrological response to climate model outputs: uncertainty caused by internal atmospheric variability

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    An approach is proposed to assess hydrological simulation uncertainty originating from internal atmospheric variability. The latter is one of three major factors contributing to uncertainty of simulated climate change projections (along with so-called "forcing" and "climate model" uncertainties). Importantly, the role of internal atmospheric variability is most visible over spatio-temporal scales of water management in large river basins. Internal atmospheric variability is represented by large ensemble simulations (45 members) with the ECHAM5 atmospheric general circulation model. Ensemble simulations are performed using identical prescribed lower boundary conditions (observed sea surface temperature, SST, and sea ice concentration, SIC, for 1979–2012) and constant external forcing parameters but different initial conditions of the atmosphere. The ensemble of bias-corrected ECHAM5 outputs and ensemble averaged ECHAM5 output are used as a distributed input for the ECOMAG and SWAP hydrological models. The corresponding ensembles of runoff hydrographs are calculated for two large rivers of the Arctic basin: the Lena and Northern Dvina rivers. A number of runoff statistics including the mean and the standard deviation of annual, monthly and daily runoff, as well as annual runoff trend, are assessed. Uncertainties of runoff statistics caused by internal atmospheric variability are estimated. It is found that uncertainty of the mean and the standard deviation of runoff has a significant seasonal dependence on the maximum during the periods of spring–summer snowmelt and summer–autumn rainfall floods. Noticeable nonlinearity of the hydrological models' results in the ensemble ECHAM5 output is found most strongly expressed for the Northern Dvina River basin. It is shown that the averaging over ensemble members effectively filters the stochastic term related to internal atmospheric variability. Simulated discharge trends are close to normally distributed around the ensemble mean value, which fits well to empirical estimates and, for the Lena River, indicates that a considerable portion of the observed trend can be externally driven

    Perturbation of a lattice spectral band by a nearby resonance

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    A soluble model of weakly coupled "molecular" and "nuclear" Hamiltonians is studied in order to exhibit explicitly the mechanism leading to the enhancement of fusion probability in case of a narrow near-threshold nuclear resonance. We, further, consider molecular cells of this type being arranged in lattice structures. It is shown that if the real part of the narrow nuclear resonance lies within the molecular band generated by the intercellular interaction, an enhancement, proportional to the inverse width of the nuclear resonance, is to be expected.Comment: RevTeX, 2 figures within the file. In May 2000 the title changed and some minor corrections have been don

    The ^4He trimer as an Efimov system

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    We review the results obtained in the last four decades which demonstrate the Efimov nature of the 4^4He three-atomic system.Comment: Review article for a special issue of the Few-Body Systems journal devoted to Efimov physic

    Resonances in the three-neutron system

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    A study of 3-body resonances has been performed in the framework of configuration space Faddeev equations. The importance of keeping a sufficient number of terms in the asymptotic expansion of the resonance wave function is pointed out. We investigated three neutrons interacting in selected force components taken from realistic nn forces.Comment: 38 pages, 11 tables, 4 figure

    РАЗРАБОТКА СМК, ВНЕДРЕНИЕ И СЕРТИФИКАЦИЯ НА ПЕРЕРАБАТЫВАЮЩИХ ПРЕДПРИЯТИЯХ ПО МЕЖДУНАРОДНЫМ СТАНДАРТАМ ИСО 9000

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    The article contains a brief product (and service) quality description. An algorithm of quality improvement is presented, and reserves forming algorithm (reserves term system creation; reserves classification; detection of the main point and the whole reserves building up structure); b) reserves diagnostic (reserves identification; reserves measuring and control); c) reserves systematization (reserves quality system development; overcoming of economic environment resistibility; application of reserves control system); d) achieved level of dynamic product quality retention (reserves control system examination; control system supervision). QMS development steps at food industry enterprises and reprocessors and their certification according to ISO 9000: a) analysis of QMS development and application initial state; planning of QMS development and application; b) extension courses organization to teach all kinds of managers and specialists base principles of effective QMS development; c) QMS documentation development (quality guide, enterprise standards, instructions etc.); d) QMS application. Audit forms. QMS documentation and processes detection and description. Some methods are recommended to solve quality and safety problems for food product and its accordance to international requirements.Представлен алгоритм улучшения качества продукции: а) формирование резервов (создание терминосистемы резервов; классификация резервов; выявление сущности и структуры построения резервов); б) диагностика резервов (идентификация резервов; измерение и контроль резервов); в) систематизация резервов (разработка системы контроля резервов; преодоление сопротивляемости экономической среды; внедрение системы контроля резервов); г) удержание достигнутого уровня динамического качества продукции ПП (проверка работы системы контроля резервов; наблюдение за системой контроля). Этапы разработки системы менеджмента качества в предприятии пищевой и перерабатывающей промышленности и их сертификация по стандартам ISO 9000: а) анализ исходного состояния разработки и  внедрения системы менеджмента качества, составление плана мероприятий по разработке и внедрению СМК; б) проведение обучающих семинаров по принципам построения эффективной СМК для разных категорий руководителей и специалистов; в) разработка документов СМК (руководство по качеству, стандарты предприятия, инструкции и др.); г) внедрение СМК. Рекомендуются пути решения проблемы качества и безопасности пищевой продукции и ее соответствия международным требованиям

    Cross‐scale intercomparison of climate change impacts simulated by regional and global hydrological models in eleven large river basins

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    Ideally, the results from models operating at different scales should agree in trend direction and magnitude of impacts under climate change. However, this implies that the sensitivity to climate variability and climate change is comparable for impact models designed for either scale. In this study, we compare hydrological changes simulated by 9 global and 9 regional hydrological models (HM) for 11 large river basins in all continents under reference and scenario conditions. The foci are on model validation runs, sensitivity of annual discharge to climate variability in the reference period, and sensitivity of the long-term average monthly seasonal dynamics to climate change. One major result is that the global models, mostly not calibrated against observations, often show a considerable bias in mean monthly discharge, whereas regional models show a better reproduction of reference conditions. However, the sensitivity of the two HM ensembles to climate variability is in general similar. The simulated climate change impacts in terms of long-term average monthly dynamics evaluated for HM ensemble medians and spreads show that the medians are to a certain extent comparable in some cases, but have distinct differences in other cases, and the spreads related to global models are mostly notably larger. Summarizing, this implies that global HMs are useful tools when looking at large-scale impacts of climate change and variability. Whenever impacts for a specific river basin or region are of interest, e.g. for complex water management applications, the regional-scale models calibrated and validated against observed discharge should be used

    Dibaryon model for nuclear force and the properties of the 3N3N system

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    The dibaryon model for NNNN interaction, which implies the formation of an intermediate six-quark bag dressed by a σ\sigma-field, is applied to the 3N3N system, where it results in a new three-body force of scalar nature between the six-quark bag and a third nucleon. A new multicomponent formalism is developed to describe three-body systems with nonstatic pairwise interactions and non-nucleonic degrees of freedom. Precise variational calculations of 3N3N bound states are carried out in the dressed-bag model including the new scalar three-body force. The unified coupling constants and form factors for 2N2N and 3N3N force operators are used in the present approach, in a sharp contrast to conventional meson-exchange models. It is shown that this three-body force gives at least half the 3N3N total binding energy, while the weight of non-nucleonic components in the 3^3H and 3^3He wavefunctions can exceed 10%. The new force model provides a very good description of 3N3N bound states with a reasonable magnitude of the σNN\sigma NN coupling constant. A new Coulomb 3N3N force between the third nucleon and dibaryon is found to be very important for a correct description of the Coulomb energy and r.m.s. charge radius in 3^3He. In view of the new results for Coulomb displacement energy obtained here for A=3 nuclei, an explanation for the long-term Nolen--Schiffer paradox in nuclear physics is suggested. The role of the charge-symmetry-breaking effects in the nuclear force is discussed.Comment: 64 pages, 7 figures, LaTeX, to be published in Phys. At. Nucl. (2005
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