12 research outputs found
Dibaryon model for nuclear force and the properties of the system
The dibaryon model for interaction, which implies the formation of an
intermediate six-quark bag dressed by a -field, is applied to the
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
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 and
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 total binding energy, while the weight of
non-nucleonic components in the H and He wavefunctions can exceed 10%.
The new force model provides a very good description of bound states with
a reasonable magnitude of the coupling constant. A new Coulomb
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 He.
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
Ensemble seasonal forecast of extreme water inflow into a large reservoir
An approach to seasonal ensemble forecast of unregulated water inflow into a
large reservoir was developed. The approach is founded on a physically-based
semi-distributed hydrological model ECOMAG driven by Monte-Carlo generated
ensembles of weather scenarios for a specified lead-time of the forecast
(3 months ahead in this study). Case study was carried out for the Cheboksary
reservoir (catchment area is 374 000 km2) located on the middle Volga
River. Initial watershed conditions on the forecast date (1 March
for spring freshet and 1 June for summer low-water period) were
simulated by the hydrological model forced by daily meteorological
observations several months prior to the forecast date. A spatially
distributed stochastic weather generator was used to produce time-series of
daily weather scenarios for the forecast lead-time. Ensemble of daily water
inflow into the reservoir was obtained by driving the ECOMAG model with the
generated weather time-series. The proposed ensemble forecast technique was
verified on the basis of the hindcast simulations for 29 spring and summer
seasons beginning from 1982 (the year of the reservoir filling to capacity)
to 2010. The verification criteria were used in order to evaluate an ability
of the proposed technique to forecast freshet/low-water events of the
pre-assigned severity categories
Climate noise effect on uncertainty of hydrological extremes: numerical experiments with hydrological and climate models
An approach has been proposed to analyze the simulated hydrological extreme
uncertainty related to the internal variability of the atmosphere ("climate
noise"), which is inherent to the climate system and considered as the
lowest level of uncertainty achievable in climate impact studies. To assess
the climate noise effect, numerical experiments were made with climate model
ECHAM5 and hydrological model ECOMAG. The case study was carried out to
Northern Dvina River basin (catchment area is 360 000 km2), whose
hydrological regime is characterised by extreme freshets during
spring-summer snowmelt period. The climate noise was represented by ensemble
ECHAM5 simulations (45 ensemble members) with identical historical boundary
forcing and varying initial conditions. An ensemble of the ECHAM5-outputs
for the period of 1979–2012 was used (after bias correction post-processing)
as the hydrological model inputs, and the corresponding ensemble of 45
multi-year hydrographs was simulated. From this ensemble, we derived flood
statistic uncertainty caused by the internal variability of the atmosphere
Physically-based distributed modelling of river runoff under changing climate conditions
Physically-based distributed modelling under changing climatic conditions has been carried out for the Northern Dvina River basin using the ECOMAG (ECOlogical Model for Applied Geophysics). The parameters of the model have been adjusted through calibration against runoff hydrographs observed for the period 2000–2009. Validation of the model has been performed for the period of 1970–1989. Both sensitivity analysis and scenario approaches (based on the CMIP3 projections) have been applied to assess possible hydrological consequences of climate change in the basin. It has been shown that for greenhouse gases emissions A2 scenario, averaged for 11 climate models, annual runoff will not change significantly for the future 50 years. But due to increasing of winter precipitation by up to 15%, the volume of flow in the flood period could increase by up to 20%. Earlier beginning of the flood season is expected because of rising of the air temperature