Wave power

About: Wave power is a research topic. Over the lifetime, 2671 publications have been published within this topic receiving 41439 citations. The topic is also known as: wind wave energy & sea wave energy.

Seismic Halos around Active Regions: A Magnetohydrodynamic Theory

Abstract: Comprehending the manner in which magnetic fields affect propagating waves is a first step toward constructing accurate helioseismic models of active region subsurface structure and dynamics. Here we present a numerical method for computing the linear interaction of waves with magnetic fields embedded in a solar-like stratified background. The ideal magnetohydrodynamic (MHD) equations are solved in a three-dimensional box that straddles the solar surface, extending from 35 Mm below the photosphere to 1.2 Mm into the atmosphere. One of the challenges in performing these simulations involves generating a magnetohydrostatic (MHS) state wherein the stratification assumes horizontal inhomogeneity in addition to the strong vertical stratification associated with the near-surface layers. Keeping in mind that the aim of this effort is to understand and characterize linear MHD interactions, we discuss a means of computing statically consistent background states. Power maps computed from simulations of waves interacting with thick flux tubes that have peak photospheric field strengths of 600 and 3000 G are presented. Strong modal power reduction in the "umbral" regions of the flux tube enveloped by a halo of increased wave power is seen in the simulations with the thick flux tubes. These enhancements are also seen in Doppler velocity power maps of active regions observed in the Sun, which leads us to propose that the halo has MHD underpinnings.

Assessment of the Wave Energy in the Black Sea Based on a 15-Year Hindcast with Data Assimilation

Abstract: The principal target of the present work is to assess the wave energy potential in the Black Sea, identifying also some relevant energetic features and possible patterns. A wave prediction system based on the Simulating Waves Nearshore model (SWAN) has been implemented and intensively tested in the entire sea basin. Moreover, considering an optimal interpolation technique, an assimilation scheme of the satellite data has been developed, leading to a visible improvement of the wave model predictions in terms of significant wave heights and, consequently, also in terms of wave power. Using this wave prediction system with data assimilation, simulations have been performed for a 15-year period (1999–2013). Considering the results of this 15-year wave hindcast, an analysis of the wave energy conditions in the basin of the Black Sea has been carried out. This provided a more comprehensive picture concerning the wave energy patterns in the coastal environment of the Black Sea focused on the average wave conditions that might be expected in this sea. Following the results presented, it can be concluded that the wave energy extraction in the Black Sea can become an issue of interest, especially from the perspective of the hybrid solutions.

The magnetron as a generator of centimeter waves

Abstract: Late in the summer of 1940, a fire control radar operating at 700 megacycles per second was in an advanced state of development at the Bell Telephone Laboratories. The pulse power of this radar was generated by a pair of triodes operating near their upper limit of frequency. Even when driven to the point where tube life was short, the generator produced peak power in each pulse of only two kilowatts, a quantity usable but marginal. Although the triodes employed had not been designed for high voltage pulsed operation, they were the best available. This is an example of how development of radar in the centimeter wave region was circumscribed by the lack of a generator of adequate power and reasonable life expectancy. Moreover, the prospects of improvement of the triode as a power generator at these wavelengths and extension of its use to shorter wavelengths were not bright. Solution of the problem by means of power amplification was remote. A new source of centimeter wave power was urgently needed.