We propose a dynamic model of investment and trade in a market of a specialized technology subject to two main frictions. First, agents cannot raise outside capital. Second, a random group of agents will have the opportunity to invest in new technology and there is no market to insure against this shock. The first friction implies the presence of invesment cycles with abundant invesment and low...

Sonic boom research conducted at NASA through the Supersonics Project of the Fundamental Aeronautics Program is oriented toward understanding the potential impact of sonic boom noise on communities from new low-boom supersonic aircraft designs. Encompassing research in atmospheric propagation, structural response, and human response, NASA research contributes to knowledge in key areas needed to...

The log-periodic dipole array (LPDA) has become the most popular commercial antenna for reception of TV signal in VHF and UHF bands in Europe. The antenna consists of two booms of a square cross section to which dipoles are attached (Figure 1). The booms play the role of the feeding two-conductor line. The dimensions of the boom are relatively large compared to the wavelength and the dipole len...