1,724,992 research outputs found
Do states respond differently to changes in monetary policy?
Full text linkDo the proportion of interest-sensitive industries, the number of small firms, and the concentration of small banks determine how monetary policy influences state economies? In this article, Jerry Carlino and Bob DeFina extend to the state level their earlier study that looked at these factors and their effects on a region's economies. Are the responses the same? Read the results of Carlino and DeFina's studyMonetary policy ; Regional economics
Diffusion in floating particles in flow through emergent vegetation: Further experimental investigations
No full textIn this paper we present the results of a new laboratory
investigation aimed at providing a better understanding of the
transport and diffusion processes of floating particles (e.g.,
buoyant seeds) in open channel flow with emergent vegetation. The
experiments are designed primarily to study the influence of
vegetation density and flow velocity on the relevant interaction
mechanisms between particles and vegetation. The aim is also to
ascertain the validity of a stochastic model recently proposed by Defina and Peruzzo [2010].
We find that i) the proper definition of plant spacing is given
as 1/np dp, dp being the plant diameter, np the number
of plants per unit area; ii) the particle retention time
distribution can be satisfactorily approximated by a weighted
combination of two exponential distributions; iii) flow velocity
has a significant influence on the retention time and on the
efficiency of the different trapping mechanisms, and iv)
vegetation pattern and density have a minor influence on the
probability of capture and on the retention time of particles}.
Indeed, the comparison between model predictions and experimental
results is satisfactory and suggests that the observed relevant
aspects of the particle-vegetation interaction processes are
properly described by the model
Bed friction effects on the stability of a stationary hydraulic jump in a rectangular upward sloping channel
No full textThe issue of the bed friction effect on the stability of a stationary hydraulic jump in a rectangular upward sloping channel is investigated through a combined theoretical and experimental approach. The theoretical stability criterion proposed by Defina and Susin [Phys. Fluids 15, 3883 (2003) ] is generalized to include rough wall flows. The results of an extensive series of experiments are then presented. The adopted experimental procedure is detailed, and results are compared with theoretical predictions. It is shown that the proposed stability criterion successfully predicts both the stable and unstable behavior of the jump for smooth and rough wall flow, at least in the range of small upward bottom slope
Numerical experiments on bar growth
No full textA two-dimensional finite element model for the morphodynamic evolution of a cohesionless bed is presented and tested against experimental observations of the formation and evolution of free bars. The model is then employed to study the strongly nonlinear interactions governing bar development. The attention is focused on the influence of the initial perturbation introduced in the flow field for bar inception. It is found that the type of the disturbance plays a role of utmost importance as it can strongly affect both the developing process and the equilibrium conditions
Two dimensional shallow flow equations for partially dry areas
No full textA new set of two-dimensional shallow flow equations is developed in order to
deal with partially wet and very irregular domains. The bottom irregularities, which in
many practical cases strongly affect the dynamics and the continuity, are accounted for
statistically. Assuming hydrostatic approximation, the three-dimensional Reynolds
equations are suitably averaged over a representative elementary area and then integrated
over the depth. The resulting subgrid model for ground irregularities is tested by resolving
two sample problems. The first concerns the wetting and drying of tidal flats; the second
deals with overland flow on an irregular plane surface. Numerical simulations show that
the proposed equations are a useful tool for modelers who have to cope with partially dry
domains
Alcune considerazioni sulla modellazione matematica di correnti bidimensionali caratterizzate da piccoli tiranti
No full text
Procedimento matematico per la valutazione della resistenza al moto offerta da una schiera di cilindri in una corrente a superficie libera
No full text- …
