Fractal features of oscillatory convection in the half-floating zone

Unsteady and two-dimensional numerical simulation is applied to study the transition process from steady convection to turbulence via subharmonic bifurcation in thermocapillary convection of a liquid bridge in the half-floating zone. The results of numerical tests show clearly the fractal structure of period-doubling bifurcations, and frequency-locking at f/4, f/8, f/16 with basic frequency f is observed with increasing temperature difference. The Feigenbaum universal constant is given by the present paper as delta(4) = 4.853, which can be compared with the theoretical value 4.6642016.

Some features of the turbulence produced by rising air bubbles in water

Presented in this paper is an experimental study on the characteristics of the turbulence produced by rising air bubbles in water. The measurements of turbulent velocities were made by using visualization technique of particle streak and computer image processing of the flow field. The turbulence features have been examined, showing that the rising bubble-produced turbulence can be approximately modeled by homogeneous turbulence as in the case of grid turbulence in air.

New Keynesian Model Features that Can Reproduce Lead, Lag and Persistence Patterns

This paper uses a new method for describing dynamic comovement and persistence in economic time series which builds on the contemporaneous forecast error method developed in den Haan (2000). This data description method is then used to address issues in New Keynesian model performance in two ways. First, well known data patterns, such as output and inflation leads and lags and inflation persistence, are decomposed into forecast horizon components to give a more complete description of the data patterns. These results show that the well known lead and lag patterns between output and inflation arise mostly in the medium term forecasts horizons. Second, the data summary method is used to investigate a rich New Keynesian model with many modeling features to see which of these features can reproduce lead, lag and persistence patterns seen in the data. Many studies have suggested that a backward looking component in the Phillips curve is needed to match the data, but our simulations show this is not necessary. We show that a simple general equilibrium model with persistent IS curve shocks and persistent supply shocks can reproduce the lead, lag and persistence patterns seen in the data.

Cyclical Features of Uzawa-Lucas Endogenous Growth Model

This paper analyzes the cyclical properties of a generalized version of Uzawa-Lucas endogenous growth model. We study the dynamic features of different cyclical components of this model characterized by a variety of decomposition methods. The decomposition methods considered can be classified in two groups. On the one hand, we consider three statistical filters: the Hodrick-Prescott filter, the Baxter-King filter and Gonzalo-Granger decomposition. On the other hand, we use four model-based decomposition methods. The latter decomposition procedures share the property that the cyclical components obtained by these methods preserve the log-linear approximation of the Euler-equation restrictions imposed by the agent’s intertemporal optimization problem. The paper shows that both model dynamics and model performance substantially vary across decomposition methods. A parallel exercise is carried out with a standard real business cycle model. The results should help researchers to better understand the performance of Uzawa-Lucas model in relation to standard business cycle models under alternative definitions of the business cycle.

Interim report on the hydrologic features of the Green Swamp area in Central Florida

The Green Swamp area in central Florida is another area where man is developing agricultural land from marginal land. Though the area is by no means as extensive as that of the Everglades, the present efforts for its development are similar to the early efforts for developing the Everglades in that many miles of canals and ditches have been constructed to improve the drainage. Lest the early mistakes of the Everglades be repeated, the Florida Department of Water Resources considered that an appraisal of the physical and hydrologic features of the area was needed to determine the broad effects of draining and developing the swamp. This reconnaissance provides information required by the State of Florida for determining its responsibility and policy in regard to the Green Swamp area and for formulating future plans for water management of the area. Some of the features that have been determined are: the amount of rainfall on the area; the pattern of surfacewater drainage; the amount and direction of surface-water runoff; the direction of ground-water movement; the interrelationship of rainfall, surface water, and ground water; the effects of improved drainage facilities'; and the effects of the hydrologic environment on the chemical quality of water of the area.(PDF contains 106 pages.)