A Lagrangian for water waves

A Lagrangian for strongly nonlinear unsteady water waves (including overturning waves) is obtained. It is shown that the system of quadratic equations for the Stokes coefficients, which determine the shape of a steady wave (discovered by Longuet-Higgins 100 years after Stokes derived his system of cubic equations) directly follows from the canonical system of Lagrange equations. Applications to the investigation of the stability of water waves and to the construction of numerical schemes are pointed out

The suppression of short waves by a train of long waves

It is shown that a train of long waves can suppress a short-wave field due to four-wave resonance interactions. These interactions lead to the diffusion (in Fourier space) of the wave action of the short-wave field, so that the wave action is transported to the regions of higher wavenumbers, where it dissipates more effectively. The diffusion equation is derived

Measuring Productivity Change without Neoclassical Assumptions: A Conceptual Analysis

The measurement of productivity change (or difference) is usually based on models that make use of strong assumptions such as competitive behaviour and constant returns to scale. This survey discusses the basics of productivity measurement and shows that one can dispense with most if not all the usual, neoclassical assumptions. By virtue of its structural features, the measurement model is applicable to individual establishments and aggregates such as industries, sectors, or economies.

Introduction to Price and Productivity Measurement for Housing

This paper provides a brief introduction to a proposed new opportunity cost treatment of owner occupied housing in measures of inflation for the United States. In addition, the paper introduces, and provides links to, a collection of nine other papers that discuss various aspects of the treatment of owner occupied housing in measures of inflation for a number of nations including Canada, Germany, Iceland and the United States.Durable goods, Consumer Price Index, Cost of Living Index, Owner Occupied Housing, depreciation, hedonic regression models, rental equivalence approac

Strong ExB shear flows in the pedestal region in H-mode plasma

We report the first experimental observation of stationary zonal flows in the pedestal region of the H-mode plasma in the H-1 toroidal heliac. Strong peaks in E_r shear mark the top and foot of the density pedestal. Strong m=n=0 low-frequency (f < 0.6 kHz) zonal flows are observed in regions of increased E_r, suggesting substantial contribution of zonal flows to the spatial modulation of E_r radial profiles. Radial localization of zonal flows is correlated with a region of zero magnetic shear and low-order (7/5) rational surfaces.Comment: 4 pages, 5 figure

Analytic regimes of tokamak plasma

The paper suggests certain regimes of fusion plasma with magnetic confinement, when the Larmor radius $\lambda$ and the angle $\alpha$ (determining the orientation of the local coordinates) form an analytic function $w=\lambda e^{i\alpha}$ of complex variable $z=x_1+i x_2$ ($x_1$ and $x_2$ are coordinates of tokamak cross-section). It is known that an efficient nuclear fusion requires transport barriers, which might be due to zonal/poloidal flow; and the emergence of such flow is implied by the adiabatic extra conservation (established in a local slub). The suggested analytic regimes are based on the global extension of this extra conservation; transport barriers could spread to the entire tokamak plasma. It is interesting that in these regimes, plasma temperature reaches maximum often not at a single location (of tokamak cross-section), but at several points separated by regions of lower temperature.Comment: 3 pages, 3 figure